[patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

[patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Add an empty drivers/gpio directory for gpiolib infrastructure
and GPIO expanders.  It is populated by subsequent patches.

This won't be the only place to hold such gpio_chip code.  Many
external chips add a few GPIOs as secondary functionality (such
as MFD drivers) and platform code frequently needs to closely
integrate GPIO and IRQ support.

This is placed *early* in the build/link sequence since it's common
for other drivers to depend on GPIOs to do their work, so they must
be initialized early in the device_initcall() sequence.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
Cc: Eric Miao <eric.miao@marvell.com>
---
 arch/arm/Kconfig      |    2 ++
 drivers/Kconfig       |    2 ++
 drivers/Makefile      |    1 +
 drivers/gpio/Kconfig  |   32 ++++++++++++++++++++++++++++++++
 drivers/gpio/Makefile |    6 ++++++
 5 files changed, 43 insertions(+)

--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1040,6 +1040,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/gpio/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/power/Kconfig"
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -52,6 +52,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/gpio/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/power/Kconfig"
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -5,6 +5,7 @@
 # Rewritten to use lists instead of if-statements.
 #
 
+obj-$(CONFIG_GPIO_LIB)		+= gpio/
 obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_PARISC)		+= parisc/
 obj-$(CONFIG_RAPIDIO)		+= rapidio/
--- /dev/null
+++ b/drivers/gpio/Kconfig
@@ -0,0 +1,32 @@
+#
+# GPIO infrastructure and expanders
+#
+
+config GPIO_LIB
+	bool
+	help
+	  Platforms select gpiolib if they use this infrastructure
+	  for all their GPIOs, usually starting with ones integrated
+	  into SOC processors.
+
+menu "GPIO Support"
+	depends on GPIO_LIB
+
+config DEBUG_GPIO
+	bool "Debug GPIO calls"
+	depends on DEBUG_KERNEL
+	help
+	  Say Y here to add some extra checks and diagnostics to GPIO calls.
+	  The checks help ensure that GPIOs have been properly initialized
+	  before they are used and that sleeping calls aren not made from
+	  nonsleeping contexts.  They can make bitbanged serial protocols
+	  slower.  The diagnostics help catch the type of setup errors
+	  that are most common when setting up new platforms or boards.
+
+# put expanders in the right section, in alphabetical order
+
+comment "I2C GPIO expanders:"
+
+comment "SPI GPIO expanders:"
+
+endmenu
--- /dev/null
+++ b/drivers/gpio/Makefile
@@ -0,0 +1,6 @@
+# gpio support: dedicated expander chips, etc
+
+ifeq ($(CONFIG_DEBUG_GPIO),y)
+EXTRA_CFLAGS += -DDEBUG
+endif
+

Re: [patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

[Sam Ravnborg]

Hi David.

> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -5,6 +5,7 @@
>  # Rewritten to use lists instead of if-statements.
>  #
>  
> +obj-$(CONFIG_GPIO_LIB)		+= gpio/
>  obj-$(CONFIG_PCI)		+= pci/
>  obj-$(CONFIG_PARISC)		+= parisc/
>  obj-$(CONFIG_RAPIDIO)		+= rapidio/
> --- /dev/null
> +++ b/drivers/gpio/Kconfig
> @@ -0,0 +1,32 @@
> +#
> +# GPIO infrastructure and expanders
> +#
> +
> +config GPIO_LIB
> +	bool
> +	help
> +	  Platforms select gpiolib if they use this infrastructure
> +	  for all their GPIOs, usually starting with ones integrated
> +	  into SOC processors.
> +

kconfig symbols that are "select" targets should be named "HAVE_" so in
this case you could use HAVE_GPIO_LIB.
This is by convention only but introduced to make it visible that this is
a config symbol supposed to be selected.

Then on top of that the HAVE_ symbols should not have any dependencies
so we avoid that "select" selects a symbol where the dependencies are
not fulfilled.

In your case you could just use
obj-y += gpio/

in the Makefile and then there is no need to actually reference the
kconfig symbol.

> --- /dev/null
> +++ b/drivers/gpio/Makefile
> @@ -0,0 +1,6 @@
> +# gpio support: dedicated expander chips, etc
> +
> +ifeq ($(CONFIG_DEBUG_GPIO),y)
> +EXTRA_CFLAGS += -DDEBUG
> +endif

Use of EXTRA_CFLAGS are deprecated. Please use:
ccflags-$(CONFIG_DEBUG_GPIO) := -DDEBUG

	Sam

Re: [patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

[David Brownell]

On Friday 28 December 2007, Sam Ravnborg wrote:
> kconfig symbols that are "select" targets should be named "HAVE_" so in
> this case you could use HAVE_GPIO_LIB.
> This is by convention only but introduced to make it visible that this is
> a config symbol supposed to be selected.

Not widely adopted yet, but of course such things take time.


> Then on top of that the HAVE_ symbols should not have any dependencies
> so we avoid that "select" selects a symbol where the dependencies are
> not fulfilled.

That limitation of "select" still seems more buglike to me than
anything else, FWIW.  Not that it matters in this case.
 

> In your case you could just use
> obj-y += gpio/
> 
> in the Makefile and then there is no need to actually reference the
> kconfig symbol.

No, that just shifts the reference into the drivers/gpio Makefilee.

 
> ccflags-$(CONFIG_DEBUG_GPIO) := -DDEBUG

Another new convention.  :)

Pretty much like the folowing, then?

- Dave


==============	CUT HERE
Kbuild/Kconfig feedback from Sam Ravnborg, adopting new conventions:

  - HAVE_* for Kconfig symbols that platforms will select

  - Descend into drivers/gpio unconditionally, letting the Makefile
    sort out the differences

  - Use "ccflags-$(CONGIF_DEBUG_GPIO) += -DDEBUG" instead of
    those ugly (but traditional) conditionals.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 arch/arm/Kconfig           |    4 +-
 arch/avr32/Kconfig         |    2 +-
 drivers/Makefile           |    2 +-
 drivers/gpio/Kconfig       |    4 ++--
 drivers/gpio/Makefile      |   10 ++++------
 include/asm-generic/gpio.h |    2 +-
 6 files changed, 10 insertions(+), 12 deletions(-)

--- at91.orig/arch/arm/Kconfig
+++ at91/arch/arm/Kconfig
@@ -346,7 +346,7 @@ config ARCH_PXA
 	select GENERIC_GPIO
 	select GENERIC_TIME
 	select GENERIC_CLOCKEVENTS
-	select GPIO_LIB
+	select HAVE_GPIO_LIB
 	help
 	  Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
 
--- at91.orig/arch/avr32/Kconfig
+++ at91/arch/avr32/Kconfig
@@ -80,7 +80,7 @@ config PLATFORM_AT32AP
 	select SUBARCH_AVR32B
 	select MMU
 	select PERFORMANCE_COUNTERS
-	select GPIO_LIB
+	select HAVE_GPIO_LIB
 
 choice
 	prompt "AVR32 CPU type"
--- at91.orig/drivers/Makefile
+++ at91/drivers/Makefile
@@ -5,7 +5,7 @@
 # Rewritten to use lists instead of if-statements.
 #
 
-obj-$(CONFIG_GPIO_LIB)		+= gpio/
+obj-y				+= gpio/
 obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_PARISC)		+= parisc/
 obj-$(CONFIG_RAPIDIO)		+= rapidio/
--- at91.orig/drivers/gpio/Kconfig
+++ at91/drivers/gpio/Kconfig
@@ -2,7 +2,7 @@
 # GPIO infrastructure and expanders
 #
 
-config GPIO_LIB
+config HAVE_GPIO_LIB
 	bool
 	help
 	  Platforms select gpiolib if they use this infrastructure
@@ -10,7 +10,7 @@ config GPIO_LIB
 	  into SOC processors.
 
 menu "GPIO Support"
-	depends on GPIO_LIB
+	depends on HAVE_GPIO_LIB
 
 config DEBUG_GPIO
 	bool "Debug GPIO calls"
--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -1,12 +1,10 @@
 # gpio support: dedicated expander chips, etc
 
+ccflags-$(CONGIF_DEBUG_GPIO)	+= -DDEBUG
+
+obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpiolib.o
+
 obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
 obj-$(CONFIG_GPIO_PCA9539)	+= pca9539.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 
-ifeq ($(CONFIG_DEBUG_GPIO),y)
-EXTRA_CFLAGS += -DDEBUG
-endif
-
-obj-$(CONFIG_GPIO_LIB) += gpiolib.o
-
--- at91.orig/include/asm-generic/gpio.h
+++ at91/include/asm-generic/gpio.h
@@ -1,7 +1,7 @@
 #ifndef _ASM_GENERIC_GPIO_H
 #define _ASM_GENERIC_GPIO_H
 
-#ifdef CONFIG_GPIO_LIB
+#ifdef CONFIG_HAVE_GPIO_LIB
 
 /* Platforms may implement their GPIO interface with library code,
  * at a small performance cost for non-inlined operations and some

Re: [patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

[Sam Ravnborg]

On Sat, Dec 29, 2007 at 10:19:39AM -0800, David Brownell wrote:
> On Friday 28 December 2007, Sam Ravnborg wrote:
> > kconfig symbols that are "select" targets should be named "HAVE_" so in
> > this case you could use HAVE_GPIO_LIB.
> > This is by convention only but introduced to make it visible that this is
> > a config symbol supposed to be selected.
> 
> Not widely adopted yet, but of course such things take time.

Yes - which is why I am a bit more careful to note it.
> 
> 
> > Then on top of that the HAVE_ symbols should not have any dependencies
> > so we avoid that "select" selects a symbol where the dependencies are
> > not fulfilled.
> 
> That limitation of "select" still seems more buglike to me than
> anything else, FWIW.  Not that it matters in this case.
But I had not yet figured out how to fix it - and limiting select
to symbols without dependencies avoid the worst offendes/abusers.

> Pretty much like the folowing, then?
> 
>   - Use "ccflags-$(CONGIF_DEBUG_GPIO) += -DDEBUG" instead of
>     those ugly (but traditional) conditionals.

s/CONGIF/CONFIG/


>  
> +ccflags-$(CONGIF_DEBUG_GPIO)	+= -DDEBUG
> +
s/CONGIF/CONFIG/

Otherwise OK.

	Sam

Re: [patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Add an empty drivers/gpio directory for gpiolib infrastructure
and GPIO expanders.  It will be populated by later patches.

This won't be the only place to hold such gpio_chip code.  Many
external chips add a few GPIOs as secondary functionality (such
as MFD drivers) and platform code frequently needs to closely
integrate GPIO and IRQ support.

This is placed *early* in the build/link sequence since it's common
for other drivers to depend on GPIOs to do their work, so they must
be initialized early in the device_initcall() sequence.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
Cc: Eric Miao <eric.miao@marvell.com>
---
Incorporates cleanup as suggested by Sam Ravnborg:  use HAVE_*
and a new idiom for adding "-DDEBUG".

 arch/arm/Kconfig      |    2 ++
 drivers/Kconfig       |    2 ++
 drivers/Makefile      |    1 +
 drivers/gpio/Kconfig  |   32 ++++++++++++++++++++++++++++++++
 drivers/gpio/Makefile |    4 ++++
 5 files changed, 41 insertions(+)

--- at91.orig/arch/arm/Kconfig	2008-01-05 12:00:45.000000000 -0800
+++ at91/arch/arm/Kconfig	2008-01-05 12:00:47.000000000 -0800
@@ -1040,6 +1040,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/gpio/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/power/Kconfig"
--- at91.orig/drivers/Kconfig	2008-01-05 12:00:45.000000000 -0800
+++ at91/drivers/Kconfig	2008-01-05 12:00:47.000000000 -0800
@@ -52,6 +52,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/gpio/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/power/Kconfig"
--- at91.orig/drivers/Makefile	2008-01-05 12:00:45.000000000 -0800
+++ at91/drivers/Makefile	2008-01-05 12:00:47.000000000 -0800
@@ -5,6 +5,7 @@
 # Rewritten to use lists instead of if-statements.
 #
 
+obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpio/
 obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_PARISC)		+= parisc/
 obj-$(CONFIG_RAPIDIO)		+= rapidio/
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/drivers/gpio/Kconfig	2008-01-05 12:00:47.000000000 -0800
@@ -0,0 +1,32 @@
+#
+# GPIO infrastructure and expanders
+#
+
+config HAVE_GPIO_LIB
+	bool
+	help
+	  Platforms select gpiolib if they use this infrastructure
+	  for all their GPIOs, usually starting with ones integrated
+	  into SOC processors.
+
+menu "GPIO Support"
+	depends on HAVE_GPIO_LIB
+
+config DEBUG_GPIO
+	bool "Debug GPIO calls"
+	depends on DEBUG_KERNEL
+	help
+	  Say Y here to add some extra checks and diagnostics to GPIO calls.
+	  The checks help ensure that GPIOs have been properly initialized
+	  before they are used and that sleeping calls aren not made from
+	  nonsleeping contexts.  They can make bitbanged serial protocols
+	  slower.  The diagnostics help catch the type of setup errors
+	  that are most common when setting up new platforms or boards.
+
+# put expanders in the right section, in alphabetical order
+
+comment "I2C GPIO expanders:"
+
+comment "SPI GPIO expanders:"
+
+endmenu
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/drivers/gpio/Makefile	2008-01-05 12:00:47.000000000 -0800
@@ -0,0 +1,4 @@
+# gpio support: dedicated expander chips, etc
+
+ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
+

[patch 2.6.24-rc6-mm 2/9] gpiolib: add gpio provider infrastructure

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Provide new implementation infrastructure that platforms may choose to use
to support the GPIO programming interface.  Platforms can update current
GPIO support to use this.  In many cases the incremental cost to access a
non-inlined GPIO should be less than a dozen instructions, with the memory
cost being about a page (total) of extra data and code.  The upside is:

  * Providing two features which were "want to have (but OK to defer)" when
    GPIO interfaces were first discussed in November 2006:

    -	A "struct gpio_chip" to plug in GPIOs that aren't directly supported
	by SOC platforms, but come from FPGAs or other multifunction devices
	using conventional device registers (like UCB-1x00 or SM501 GPIOs,
	and southbridges in PCs with more open specs than usual).

    -	Full support for message-based GPIO expanders, where registers are
	accessed through sleeping I/O calls.  Previous support for these
	"cansleep" calls was just stubs.  (One example: the widely used
	pcf8574 I2C chips, with 8 GPIOs each.)

  * Including a non-stub implementation of the gpio_{request,free}() calls,
    making those calls much more useful.  The diagnostic labels are also
    recorded given DEBUG_FS, so /sys/kernel/debug/gpio can show a snapshot
    of all GPIOs known to this infrastructure.

The driver programming interfaces introduced in 2.6.21 do not change at all;
this infrastructure is entirely below those covers.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/gpio/Makefile      |    2 
 drivers/gpio/gpiolib.c     |  567 +++++++++++++++++++++++++++++++++++++++++++++
 include/asm-generic/gpio.h |   98 +++++++
 3 files changed, 667 insertions(+)

--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -4,3 +4,5 @@ ifeq ($(CONFIG_DEBUG_GPIO),y)
 EXTRA_CFLAGS += -DDEBUG
 endif
 
+obj-$(CONFIG_GPIO_LIB) += gpiolib.o
+
--- /dev/null
+++ at91/drivers/gpio/gpiolib.c
@@ -0,0 +1,567 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+
+#include <asm/gpio.h>
+
+
+/* Optional implementation infrastructure for GPIO interfaces.
+ *
+ * Platforms may want to use this if they tend to use very many GPIOs
+ * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
+ *
+ * When kernel footprint or instruction count is an issue, simpler
+ * implementations may be preferred.  The GPIO programming interface
+ * allows for inlining speed-critical get/set operations for common
+ * cases, so that access to SOC-integrated GPIOs can sometimes cost
+ * only an instruction or two per bit.
+ */
+
+
+/* When debugging, extend minimal trust to callers and platform code.
+ * Also emit diagnostic messages that may help initial bringup, when
+ * board setup or driver bugs are most common.
+ *
+ * Otherwise, minimize overhead in what may be bitbanging codepaths.
+ */
+#ifdef	DEBUG
+#define	extra_checks	1
+#else
+#define	extra_checks	0
+#endif
+
+/* gpio_lock prevents conflicts during gpio_desc[] table updates.
+ * While any GPIO is requested, its gpio_chip is not removable;
+ * each GPIO's "requested" flag serves as a lock and refcount.
+ */
+static DEFINE_SPINLOCK(gpio_lock);
+
+struct gpio_desc {
+	struct gpio_chip	*chip;
+	unsigned long		flags;
+/* flag symbols are bit numbers */
+#define FLAG_REQUESTED	0
+#define FLAG_IS_OUT	1
+
+#ifdef CONFIG_DEBUG_FS
+	const char		*label;
+#endif
+};
+static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
+
+
+/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
+ * when setting direction, and otherwise illegal.  Until board setup code
+ * and drivers use explicit requests everywhere (which won't happen when
+ * those calls have no teeth) we can't avoid autorequesting.  This nag
+ * message should motivate switching to explicit requests...
+ */
+static void gpio_ensure_requested(struct gpio_desc *desc)
+{
+	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
+		pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
+#ifdef CONFIG_DEBUG_FS
+		desc->label = "[auto]";
+#endif
+	}
+}
+
+/* caller holds gpio_lock *OR* gpio is marked as requested */
+static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
+{
+	return gpio_desc[gpio].chip;
+}
+
+/**
+ * gpiochip_add() - register a gpio_chip
+ * @chip: the chip to register, with chip->base initialized
+ * Context: potentially before irqs or kmalloc will work
+ *
+ * Returns a negative errno if the chip can't be registered, such as
+ * because the chip->base is invalid or already associated with a
+ * different chip.  Otherwise it returns zero as a success code.
+ */
+int gpiochip_add(struct gpio_chip *chip)
+{
+	unsigned long	flags;
+	int		status = 0;
+	unsigned	id;
+
+	/* NOTE chip->base negative is reserved to mean a request for
+	 * dynamic allocation.  We don't currently support that.
+	 */
+
+	if (chip->base < 0 || (chip->base  + chip->ngpio) >= ARCH_NR_GPIOS) {
+		status = -EINVAL;
+		goto fail;
+	}
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	/* these GPIO numbers must not be managed by another gpio_chip */
+	for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+		if (gpio_desc[id].chip != NULL) {
+			status = -EBUSY;
+			break;
+		}
+	}
+	if (status == 0) {
+		for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+			gpio_desc[id].chip = chip;
+			gpio_desc[id].flags = 0;
+		}
+	}
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+fail:
+	/* failures here can mean systems won't boot... */
+	if (status)
+		pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
+			chip->base, chip->base + chip->ngpio,
+			chip->label ? : "generic");
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpiochip_add);
+
+/**
+ * gpiochip_remove() - unregister a gpio_chip
+ * @chip: the chip to unregister
+ *
+ * A gpio_chip with any GPIOs still requested may not be removed.
+ */
+int gpiochip_remove(struct gpio_chip *chip)
+{
+	unsigned long	flags;
+	int		status = 0;
+	unsigned	id;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+		if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
+			status = -EBUSY;
+			break;
+		}
+	}
+	if (status == 0) {
+		for (id = chip->base; id < chip->base + chip->ngpio; id++)
+			gpio_desc[id].chip = NULL;
+	}
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpiochip_remove);
+
+
+/* These "optional" allocation calls help prevent drivers from stomping
+ * on each other, and help provide better diagnostics in debugfs.
+ * They're called even less than the "set direction" calls.
+ */
+int gpio_request(unsigned gpio, const char *label)
+{
+	struct gpio_desc	*desc;
+	int			status = -EINVAL;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (gpio >= ARCH_NR_GPIOS)
+		goto done;
+	desc = &gpio_desc[gpio];
+	if (desc->chip == NULL)
+		goto done;
+
+	/* NOTE:  gpio_request() can be called in early boot,
+	 * before IRQs are enabled.
+	 */
+
+	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
+#ifdef CONFIG_DEBUG_FS
+		desc->label = (label == NULL) ? "?" : label;
+#endif
+		status = 0;
+	} else
+		status = -EBUSY;
+
+done:
+	if (status)
+		pr_debug("gpio_request: gpio-%d (%s) status %d\n",
+			gpio, label ? : "?", status);
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_request);
+
+void gpio_free(unsigned gpio)
+{
+	unsigned long		flags;
+	struct gpio_desc	*desc;
+
+	if (gpio >= ARCH_NR_GPIOS) {
+		WARN_ON(extra_checks);
+		return;
+	}
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	desc = &gpio_desc[gpio];
+	if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) {
+#ifdef CONFIG_DEBUG_FS
+		desc->label = NULL;
+#endif
+	} else
+		WARN_ON(extra_checks);
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gpio_free);
+
+
+/**
+ * gpiochip_is_requested - return string iff signal was requested
+ * @chip: controller managing the signal
+ * @offset: of signal within controller's 0..(ngpio - 1) range
+ *
+ * Returns NULL if the GPIO is not currently requested, else a string.
+ * If debugfs support is enabled, the string returned is the label passed
+ * to gpio_request(); otherwise it is a meaningless constant.
+ *
+ * This function is for use by GPIO controller drivers.  The label can
+ * help with diagnostics, and knowing that the signal is used as a GPIO
+ * can help avoid accidentally multiplexing it to another controller.
+ */
+const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned gpio = chip->base + offset;
+
+	if (gpio >= ARCH_NR_GPIOS || gpio_desc[gpio].chip != chip)
+		return NULL;
+	if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
+		return NULL;
+#ifdef CONFIG_DEBUG_FS
+	return gpio_desc[gpio].label;
+#else
+	return "?";
+#endif
+}
+EXPORT_SYMBOL_GPL(gpiochip_is_requested);
+
+
+/* Drivers MUST set GPIO direction before making get/set calls.  In
+ * some cases this is done in early boot, before IRQs are enabled.
+ *
+ * As a rule these aren't called more than once (except for drivers
+ * using the open-drain emulation idiom) so these are natural places
+ * to accumulate extra debugging checks.  Note that we can't (yet)
+ * rely on gpio_request() having been called beforehand.
+ */
+
+int gpio_direction_input(unsigned gpio)
+{
+	unsigned long		flags;
+	struct gpio_chip	*chip;
+	struct gpio_desc	*desc = &gpio_desc[gpio];
+	int			status = -EINVAL;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (gpio >= ARCH_NR_GPIOS)
+		goto fail;
+	chip = desc->chip;
+	if (!chip || !chip->get || !chip->direction_input)
+		goto fail;
+	gpio -= chip->base;
+	if (gpio >= chip->ngpio)
+		goto fail;
+	gpio_ensure_requested(desc);
+
+	/* now we know the gpio is valid and chip won't vanish */
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	might_sleep_if(extra_checks && chip->can_sleep);
+
+	status = chip->direction_input(chip, gpio);
+	if (status == 0)
+		clear_bit(FLAG_IS_OUT, &desc->flags);
+	return status;
+fail:
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	if (status)
+		pr_debug("%s: gpio-%d status %d\n",
+			__FUNCTION__, gpio, status);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_direction_input);
+
+int gpio_direction_output(unsigned gpio, int value)
+{
+	unsigned long		flags;
+	struct gpio_chip	*chip;
+	struct gpio_desc	*desc = &gpio_desc[gpio];
+	int			status = -EINVAL;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (gpio >= ARCH_NR_GPIOS)
+		goto fail;
+	chip = desc->chip;
+	if (!chip || !chip->set || !chip->direction_output)
+		goto fail;
+	gpio -= chip->base;
+	if (gpio >= chip->ngpio)
+		goto fail;
+	gpio_ensure_requested(desc);
+
+	/* now we know the gpio is valid and chip won't vanish */
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	might_sleep_if(extra_checks && chip->can_sleep);
+
+	status = chip->direction_output(chip, gpio, value);
+	if (status == 0)
+		set_bit(FLAG_IS_OUT, &desc->flags);
+	return status;
+fail:
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	if (status)
+		pr_debug("%s: gpio-%d status %d\n",
+			__FUNCTION__, gpio, status);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_direction_output);
+
+
+/* I/O calls are only valid after configuration completed; the relevant
+ * "is this a valid GPIO" error checks should already have been done.
+ *
+ * "Get" operations are often inlinable as reading a pin value register,
+ * and masking the relevant bit in that register.
+ *
+ * When "set" operations are inlinable, they involve writing that mask to
+ * one register to set a low value, or a different register to set it high.
+ * Otherwise locking is needed, so there may be little value to inlining.
+ *
+ *------------------------------------------------------------------------
+ *
+ * IMPORTANT!!!  The hot paths -- get/set value -- assume that callers
+ * have requested the GPIO.  That can include implicit requesting by
+ * a direction setting call.  Marking a gpio as requested locks its chip
+ * in memory, guaranteeing that these table lookups need no more locking
+ * and that gpiochip_remove() will fail.
+ *
+ * REVISIT when debugging, consider adding some instrumentation to ensure
+ * that the GPIO was actually requested.
+ */
+
+/**
+ * __gpio_get_value() - return a gpio's value
+ * @gpio: gpio whose value will be returned
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_get_value().
+ * It returns the zero or nonzero value provided by the associated
+ * gpio_chip.get() method; or zero if no such method is provided.
+ */
+int __gpio_get_value(unsigned gpio)
+{
+	struct gpio_chip	*chip;
+
+	chip = gpio_to_chip(gpio);
+	WARN_ON(extra_checks && chip->can_sleep);
+	return chip->get ? chip->get(chip, gpio - chip->base) : 0;
+}
+EXPORT_SYMBOL_GPL(__gpio_get_value);
+
+/**
+ * __gpio_set_value() - assign a gpio's value
+ * @gpio: gpio whose value will be assigned
+ * @value: value to assign
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_set_value().
+ * It invokes the associated gpio_chip.set() method.
+ */
+void __gpio_set_value(unsigned gpio, int value)
+{
+	struct gpio_chip	*chip;
+
+	chip = gpio_to_chip(gpio);
+	WARN_ON(extra_checks && chip->can_sleep);
+	chip->set(chip, gpio - chip->base, value);
+}
+EXPORT_SYMBOL_GPL(__gpio_set_value);
+
+/**
+ * __gpio_cansleep() - report whether gpio value access will sleep
+ * @gpio: gpio in question
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_cansleep().  It
+ * returns nonzero if access reading or writing the GPIO value can sleep.
+ */
+int __gpio_cansleep(unsigned gpio)
+{
+	struct gpio_chip	*chip;
+
+	/* only call this on GPIOs that are valid! */
+	chip = gpio_to_chip(gpio);
+
+	return chip->can_sleep;
+}
+EXPORT_SYMBOL_GPL(__gpio_cansleep);
+
+
+
+/* There's no value in making it easy to inline GPIO calls that may sleep.
+ * Common examples include ones connected to I2C or SPI chips.
+ */
+
+int gpio_get_value_cansleep(unsigned gpio)
+{
+	struct gpio_chip	*chip;
+
+	might_sleep_if(extra_checks);
+	chip = gpio_to_chip(gpio);
+	return chip->get(chip, gpio - chip->base);
+}
+EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
+
+void gpio_set_value_cansleep(unsigned gpio, int value)
+{
+	struct gpio_chip	*chip;
+
+	might_sleep_if(extra_checks);
+	chip = gpio_to_chip(gpio);
+	chip->set(chip, gpio - chip->base, value);
+}
+EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
+
+
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+
+static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
+{
+	unsigned		i;
+	unsigned		gpio = chip->base;
+	struct gpio_desc	*gdesc = &gpio_desc[gpio];
+	int			is_out;
+
+	for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
+		if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
+			continue;
+
+		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
+		seq_printf(s, " gpio-%-3d (%-12s) %s %s",
+			gpio, gdesc->label,
+			is_out ? "out" : "in ",
+			chip->get
+				? (chip->get(chip, i) ? "hi" : "lo")
+				: "?  ");
+
+		if (!is_out) {
+			int		irq = gpio_to_irq(gpio);
+			struct irq_desc	*desc = irq_desc + irq;
+
+			/* This races with request_irq(), set_irq_type(),
+			 * and set_irq_wake() ... but those are "rare".
+			 *
+			 * More significantly, trigger type flags aren't
+			 * currently maintained by genirq.
+			 */
+			if (irq >= 0 && desc->action) {
+				char *trigger;
+
+				switch (desc->status & IRQ_TYPE_SENSE_MASK) {
+				case IRQ_TYPE_NONE:
+					trigger = "(default)";
+					break;
+				case IRQ_TYPE_EDGE_FALLING:
+					trigger = "edge-falling";
+					break;
+				case IRQ_TYPE_EDGE_RISING:
+					trigger = "edge-rising";
+					break;
+				case IRQ_TYPE_EDGE_BOTH:
+					trigger = "edge-both";
+					break;
+				case IRQ_TYPE_LEVEL_HIGH:
+					trigger = "level-high";
+					break;
+				case IRQ_TYPE_LEVEL_LOW:
+					trigger = "level-low";
+					break;
+				default:
+					trigger = "?trigger?";
+					break;
+				}
+
+				seq_printf(s, " irq-%d %s%s",
+					irq, trigger,
+					(desc->status & IRQ_WAKEUP)
+						? " wakeup" : "");
+			}
+		}
+
+		seq_printf(s, "\n");
+	}
+}
+
+static int gpiolib_show(struct seq_file *s, void *unused)
+{
+	struct gpio_chip	*chip = NULL;
+	unsigned		gpio;
+	int			started = 0;
+
+	/* REVISIT this isn't locked against gpio_chip removal ... */
+
+	for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
+		if (chip == gpio_desc[gpio].chip)
+			continue;
+		chip = gpio_desc[gpio].chip;
+		if (!chip)
+			continue;
+
+		seq_printf(s, "%sGPIOs %d-%d, %s%s:\n",
+				started ? "\n" : "",
+				chip->base, chip->base + chip->ngpio - 1,
+				chip->label ? : "generic",
+				chip->can_sleep ? ", can sleep" : "");
+		started = 1;
+		if (chip->dbg_show)
+			chip->dbg_show(s, chip);
+		else
+			gpiolib_dbg_show(s, chip);
+	}
+	return 0;
+}
+
+static int gpiolib_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, gpiolib_show, NULL);
+}
+
+static struct file_operations gpiolib_operations = {
+	.open		= gpiolib_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init gpiolib_debugfs_init(void)
+{
+	/* /sys/kernel/debug/gpio */
+	(void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
+				NULL, NULL, &gpiolib_operations);
+	return 0;
+}
+subsys_initcall(gpiolib_debugfs_init);
+
+#endif	/* DEBUG_FS */
--- at91.orig/include/asm-generic/gpio.h
+++ at91/include/asm-generic/gpio.h
@@ -1,6 +1,102 @@
 #ifndef _ASM_GENERIC_GPIO_H
 #define _ASM_GENERIC_GPIO_H
 
+#ifdef CONFIG_GPIO_LIB
+
+/* Platforms may implement their GPIO interface with library code,
+ * at a small performance cost for non-inlined operations and some
+ * extra memory (for code and for per-GPIO table entries).
+ *
+ * While the GPIO programming interface defines valid GPIO numbers
+ * to be in the range 0..MAX_INT, this library restricts them to the
+ * smaller range 0..ARCH_NR_GPIOS.
+ */
+
+#ifndef ARCH_NR_GPIOS
+#define ARCH_NR_GPIOS		256
+#endif
+
+struct seq_file;
+
+/**
+ * struct gpio_chip - abstract a GPIO controller
+ * @label: for diagnostics
+ * @direction_input: configures signal "offset" as input, or returns error
+ * @get: returns value for signal "offset"; for output signals this
+ *	returns either the value actually sensed, or zero
+ * @direction_output: configures signal "offset" as output, or returns error
+ * @set: assigns output value for signal "offset"
+ * @dbg_show: optional routine to show contents in debugfs; default code
+ *	will be used when this is omitted, but custom code can show extra
+ *	state (such as pullup/pulldown configuration).
+ * @base: identifies the first GPIO number handled by this chip; or, if
+ *	negative during registration, requests dynamic ID allocation.
+ * @ngpio: the number of GPIOs handled by this controller; the last GPIO
+ *	handled is (base + ngpio - 1).
+ * @can_sleep: flag must be set iff get()/set() methods sleep, as they
+ *	must while accessing GPIO expander chips over I2C or SPI
+ *
+ * A gpio_chip can help platforms abstract various sources of GPIOs so
+ * they can all be accessed through a common programing interface.
+ * Example sources would be SOC controllers, FPGAs, multifunction
+ * chips, dedicated GPIO expanders, and so on.
+ *
+ * Each chip controls a number of signals, identified in method calls
+ * by "offset" values in the range 0..(@ngpio - 1).  When those signals
+ * are referenced through calls like gpio_get_value(gpio), the offset
+ * is calculated by subtracting @base from the gpio number.
+ */
+struct gpio_chip {
+	char			*label;
+
+	int			(*direction_input)(struct gpio_chip *chip,
+						unsigned offset);
+	int			(*get)(struct gpio_chip *chip,
+						unsigned offset);
+	int			(*direction_output)(struct gpio_chip *chip,
+						unsigned offset, int value);
+	void			(*set)(struct gpio_chip *chip,
+						unsigned offset, int value);
+	void			(*dbg_show)(struct seq_file *s,
+						struct gpio_chip *chip);
+	int			base;
+	u16			ngpio;
+	unsigned		can_sleep:1;
+};
+
+extern const char *gpiochip_is_requested(struct gpio_chip *chip,
+			unsigned offset);
+
+/* add/remove chips */
+extern int gpiochip_add(struct gpio_chip *chip);
+extern int __must_check gpiochip_remove(struct gpio_chip *chip);
+
+
+/* Always use the library code for GPIO management calls,
+ * or when sleeping may be involved.
+ */
+extern int gpio_request(unsigned gpio, const char *label);
+extern void gpio_free(unsigned gpio);
+
+extern int gpio_direction_input(unsigned gpio);
+extern int gpio_direction_output(unsigned gpio, int value);
+
+extern int gpio_get_value_cansleep(unsigned gpio);
+extern void gpio_set_value_cansleep(unsigned gpio, int value);
+
+
+/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
+ * the GPIO is constant and refers to some always-present controller,
+ * giving direct access to chip registers and tight bitbanging loops.
+ */
+extern int __gpio_get_value(unsigned gpio);
+extern void __gpio_set_value(unsigned gpio, int value);
+
+extern int __gpio_cansleep(unsigned gpio);
+
+
+#else
+
 /* platforms that don't directly support access to GPIOs through I2C, SPI,
  * or other blocking infrastructure can use these wrappers.
  */
@@ -22,4 +118,6 @@ static inline void gpio_set_value_cansle
 	gpio_set_value(gpio, value);
 }
 
+#endif
+
 #endif /* _ASM_GENERIC_GPIO_H */

Re: [patch 2.6.24-rc6-mm 2/9] gpiolib: add gpio provider infrastructure

[Sam Ravnborg]

Hi David.

> +/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
> + * when setting direction, and otherwise illegal.  Until board setup code
> + * and drivers use explicit requests everywhere (which won't happen when
> + * those calls have no teeth) we can't avoid autorequesting.  This nag
> + * message should motivate switching to explicit requests...
> + */
> +static void gpio_ensure_requested(struct gpio_desc *desc)
> +{
> +	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
> +		pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
> +#ifdef CONFIG_DEBUG_FS
> +		desc->label = "[auto]";
> +#endif
> +	}
For this an the other setters of desc->label a small helper function
would be better. The helper function could then contain the necessary
ifdef in only one place.


> --- at91.orig/include/asm-generic/gpio.h
> +++ at91/include/asm-generic/gpio.h
> +
> +extern const char *gpiochip_is_requested(struct gpio_chip *chip,
> +			unsigned offset);
> +
> +/* add/remove chips */
> +extern int gpiochip_add(struct gpio_chip *chip);
> +extern int __must_check gpiochip_remove(struct gpio_chip *chip);

The use of "extern" is not needed in .h files for function prototypes.

	Sam

Re: [patch 2.6.24-rc6-mm 2/9] gpiolib: add gpio provider infrastructure

[David Brownell]

On Friday 28 December 2007, Sam Ravnborg wrote:
> For this an the other setters of desc->label a small helper function
> would be better. The helper function could then contain the necessary
> ifdef in only one place.

Good point; see the appended.


> > +/* add/remove chips */
> > +extern int gpiochip_add(struct gpio_chip *chip);
> > +extern int __must_check gpiochip_remove(struct gpio_chip *chip);
> 
> The use of "extern" is not needed in .h files for function prototypes.

But it's widely used nonetheless, and many people prefer to
see those annotations.  Heck, /usr/include is full of them...

- Dave


============ CUT HERE
Minor gpiolib.c cleanup: remove most #ifdefs for CONFIG_FS.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/gpio/gpiolib.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

--- at91.orig/drivers/gpio/gpiolib.c
+++ at91/drivers/gpio/gpiolib.c
@@ -50,6 +50,12 @@ struct gpio_desc {
 };
 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
 
+static inline void desc_set_label(struct gpio_desc *d, const char *label)
+{
+#ifdef CONFIG_DEBUG_FS
+	d->label = label;
+#endif
+}
 
 /* Warn when drivers omit gpio_request() calls -- legal but ill-advised
  * when setting direction, and otherwise illegal.  Until board setup code
@@ -61,9 +67,7 @@ static void gpio_ensure_requested(struct
 {
 	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
 		pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
-#ifdef CONFIG_DEBUG_FS
-		desc->label = "[auto]";
-#endif
+		desc_set_label(desc, "[auto]");
 	}
 }
 
@@ -178,9 +182,7 @@ int gpio_request(unsigned gpio, const ch
 	 */
 
 	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
-#ifdef CONFIG_DEBUG_FS
-		desc->label = (label == NULL) ? "?" : label;
-#endif
+		desc_set_label(desc, label ? : "?");
 		status = 0;
 	} else
 		status = -EBUSY;
@@ -207,11 +209,9 @@ void gpio_free(unsigned gpio)
 	spin_lock_irqsave(&gpio_lock, flags);
 
 	desc = &gpio_desc[gpio];
-	if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) {
-#ifdef CONFIG_DEBUG_FS
-		desc->label = NULL;
-#endif
-	} else
+	if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags))
+		desc_set_label(desc, NULL);
+	else
 		WARN_ON(extra_checks);
 
 	spin_unlock_irqrestore(&gpio_lock, flags);

Re: [patch 2.6.24-rc6-mm 2/9] gpiolib: add gpio provider infrastructure

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Provide new implementation infrastructure that platforms may choose to use
when implementing the GPIO programming interface.  Platforms can update their
GPIO support to use this.  In many cases the incremental cost to access a
non-inlined GPIO should be less than a dozen instructions, with the memory
cost being about a page (total) of extra data and code.  The upside is:

  * Providing two features which were "want to have (but OK to defer)" when
    GPIO interfaces were first discussed in November 2006:

    -	A "struct gpio_chip" to plug in GPIOs that aren't directly supported
	by SOC platforms, but come from FPGAs or other multifunction devices
	using conventional device registers (like UCB-1x00 or SM501 GPIOs,
	and southbridges in PCs with more open specs than usual).

    -	Full support for message-based GPIO expanders, where registers are
	accessed through sleeping I/O calls.  Previous support for these
	"cansleep" calls was just stubs.  (One example: the widely used
	pcf8574 I2C chips, with 8 GPIOs each.)

  * Including a non-stub implementation of the gpio_{request,free}() calls,
    making those calls much more useful.  The diagnostic labels are also
    recorded given DEBUG_FS, so /sys/kernel/debug/gpio can show a snapshot
    of all GPIOs known to this infrastructure.

The driver programming interfaces introduced in 2.6.21 do not change at all;
this infrastructure is entirely below those covers.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
Incorporates cleanup as suggested by Sam Ravnborg.

 drivers/gpio/Makefile      |    2 
 drivers/gpio/gpiolib.c     |  567 +++++++++++++++++++++++++++++++++++++++++++++
 include/asm-generic/gpio.h |   98 +++++++
 3 files changed, 667 insertions(+)

--- at91.orig/drivers/gpio/Makefile	2008-01-05 12:00:47.000000000 -0800
+++ at91/drivers/gpio/Makefile	2008-01-05 12:01:01.000000000 -0800
@@ -2,3 +2,5 @@
 
 ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
 
+obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpiolib.o
+
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/drivers/gpio/gpiolib.c	2008-01-05 12:01:01.000000000 -0800
@@ -0,0 +1,567 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+
+#include <asm/gpio.h>
+
+
+/* Optional implementation infrastructure for GPIO interfaces.
+ *
+ * Platforms may want to use this if they tend to use very many GPIOs
+ * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
+ *
+ * When kernel footprint or instruction count is an issue, simpler
+ * implementations may be preferred.  The GPIO programming interface
+ * allows for inlining speed-critical get/set operations for common
+ * cases, so that access to SOC-integrated GPIOs can sometimes cost
+ * only an instruction or two per bit.
+ */
+
+
+/* When debugging, extend minimal trust to callers and platform code.
+ * Also emit diagnostic messages that may help initial bringup, when
+ * board setup or driver bugs are most common.
+ *
+ * Otherwise, minimize overhead in what may be bitbanging codepaths.
+ */
+#ifdef	DEBUG
+#define	extra_checks	1
+#else
+#define	extra_checks	0
+#endif
+
+/* gpio_lock prevents conflicts during gpio_desc[] table updates.
+ * While any GPIO is requested, its gpio_chip is not removable;
+ * each GPIO's "requested" flag serves as a lock and refcount.
+ */
+static DEFINE_SPINLOCK(gpio_lock);
+
+struct gpio_desc {
+	struct gpio_chip	*chip;
+	unsigned long		flags;
+/* flag symbols are bit numbers */
+#define FLAG_REQUESTED	0
+#define FLAG_IS_OUT	1
+
+#ifdef CONFIG_DEBUG_FS
+	const char		*label;
+#endif
+};
+static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
+
+static inline void desc_set_label(struct gpio_desc *d, const char *label)
+{
+#ifdef CONFIG_DEBUG_FS
+	d->label = label;
+#endif
+}
+
+/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
+ * when setting direction, and otherwise illegal.  Until board setup code
+ * and drivers use explicit requests everywhere (which won't happen when
+ * those calls have no teeth) we can't avoid autorequesting.  This nag
+ * message should motivate switching to explicit requests...
+ */
+static void gpio_ensure_requested(struct gpio_desc *desc)
+{
+	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
+		pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
+		desc_set_label(desc, "[auto]");
+	}
+}
+
+/* caller holds gpio_lock *OR* gpio is marked as requested */
+static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
+{
+	return gpio_desc[gpio].chip;
+}
+
+/**
+ * gpiochip_add() - register a gpio_chip
+ * @chip: the chip to register, with chip->base initialized
+ * Context: potentially before irqs or kmalloc will work
+ *
+ * Returns a negative errno if the chip can't be registered, such as
+ * because the chip->base is invalid or already associated with a
+ * different chip.  Otherwise it returns zero as a success code.
+ */
+int gpiochip_add(struct gpio_chip *chip)
+{
+	unsigned long	flags;
+	int		status = 0;
+	unsigned	id;
+
+	/* NOTE chip->base negative is reserved to mean a request for
+	 * dynamic allocation.  We don't currently support that.
+	 */
+
+	if (chip->base < 0 || (chip->base  + chip->ngpio) >= ARCH_NR_GPIOS) {
+		status = -EINVAL;
+		goto fail;
+	}
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	/* these GPIO numbers must not be managed by another gpio_chip */
+	for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+		if (gpio_desc[id].chip != NULL) {
+			status = -EBUSY;
+			break;
+		}
+	}
+	if (status == 0) {
+		for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+			gpio_desc[id].chip = chip;
+			gpio_desc[id].flags = 0;
+		}
+	}
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+fail:
+	/* failures here can mean systems won't boot... */
+	if (status)
+		pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
+			chip->base, chip->base + chip->ngpio,
+			chip->label ? : "generic");
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpiochip_add);
+
+/**
+ * gpiochip_remove() - unregister a gpio_chip
+ * @chip: the chip to unregister
+ *
+ * A gpio_chip with any GPIOs still requested may not be removed.
+ */
+int gpiochip_remove(struct gpio_chip *chip)
+{
+	unsigned long	flags;
+	int		status = 0;
+	unsigned	id;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	for (id = chip->base; id < chip->base + chip->ngpio; id++) {
+		if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
+			status = -EBUSY;
+			break;
+		}
+	}
+	if (status == 0) {
+		for (id = chip->base; id < chip->base + chip->ngpio; id++)
+			gpio_desc[id].chip = NULL;
+	}
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpiochip_remove);
+
+
+/* These "optional" allocation calls help prevent drivers from stomping
+ * on each other, and help provide better diagnostics in debugfs.
+ * They're called even less than the "set direction" calls.
+ */
+int gpio_request(unsigned gpio, const char *label)
+{
+	struct gpio_desc	*desc;
+	int			status = -EINVAL;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (gpio >= ARCH_NR_GPIOS)
+		goto done;
+	desc = &gpio_desc[gpio];
+	if (desc->chip == NULL)
+		goto done;
+
+	/* NOTE:  gpio_request() can be called in early boot,
+	 * before IRQs are enabled.
+	 */
+
+	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
+		desc_set_label(desc, label ? : "?");
+		status = 0;
+	} else
+		status = -EBUSY;
+
+done:
+	if (status)
+		pr_debug("gpio_request: gpio-%d (%s) status %d\n",
+			gpio, label ? : "?", status);
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_request);
+
+void gpio_free(unsigned gpio)
+{
+	unsigned long		flags;
+	struct gpio_desc	*desc;
+
+	if (gpio >= ARCH_NR_GPIOS) {
+		WARN_ON(extra_checks);
+		return;
+	}
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	desc = &gpio_desc[gpio];
+	if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags))
+		desc_set_label(desc, NULL);
+	else
+		WARN_ON(extra_checks);
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gpio_free);
+
+
+/**
+ * gpiochip_is_requested - return string iff signal was requested
+ * @chip: controller managing the signal
+ * @offset: of signal within controller's 0..(ngpio - 1) range
+ *
+ * Returns NULL if the GPIO is not currently requested, else a string.
+ * If debugfs support is enabled, the string returned is the label passed
+ * to gpio_request(); otherwise it is a meaningless constant.
+ *
+ * This function is for use by GPIO controller drivers.  The label can
+ * help with diagnostics, and knowing that the signal is used as a GPIO
+ * can help avoid accidentally multiplexing it to another controller.
+ */
+const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned gpio = chip->base + offset;
+
+	if (gpio >= ARCH_NR_GPIOS || gpio_desc[gpio].chip != chip)
+		return NULL;
+	if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
+		return NULL;
+#ifdef CONFIG_DEBUG_FS
+	return gpio_desc[gpio].label;
+#else
+	return "?";
+#endif
+}
+EXPORT_SYMBOL_GPL(gpiochip_is_requested);
+
+
+/* Drivers MUST set GPIO direction before making get/set calls.  In
+ * some cases this is done in early boot, before IRQs are enabled.
+ *
+ * As a rule these aren't called more than once (except for drivers
+ * using the open-drain emulation idiom) so these are natural places
+ * to accumulate extra debugging checks.  Note that we can't (yet)
+ * rely on gpio_request() having been called beforehand.
+ */
+
+int gpio_direction_input(unsigned gpio)
+{
+	unsigned long		flags;
+	struct gpio_chip	*chip;
+	struct gpio_desc	*desc = &gpio_desc[gpio];
+	int			status = -EINVAL;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (gpio >= ARCH_NR_GPIOS)
+		goto fail;
+	chip = desc->chip;
+	if (!chip || !chip->get || !chip->direction_input)
+		goto fail;
+	gpio -= chip->base;
+	if (gpio >= chip->ngpio)
+		goto fail;
+	gpio_ensure_requested(desc);
+
+	/* now we know the gpio is valid and chip won't vanish */
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	might_sleep_if(extra_checks && chip->can_sleep);
+
+	status = chip->direction_input(chip, gpio);
+	if (status == 0)
+		clear_bit(FLAG_IS_OUT, &desc->flags);
+	return status;
+fail:
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	if (status)
+		pr_debug("%s: gpio-%d status %d\n",
+			__FUNCTION__, gpio, status);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_direction_input);
+
+int gpio_direction_output(unsigned gpio, int value)
+{
+	unsigned long		flags;
+	struct gpio_chip	*chip;
+	struct gpio_desc	*desc = &gpio_desc[gpio];
+	int			status = -EINVAL;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	if (gpio >= ARCH_NR_GPIOS)
+		goto fail;
+	chip = desc->chip;
+	if (!chip || !chip->set || !chip->direction_output)
+		goto fail;
+	gpio -= chip->base;
+	if (gpio >= chip->ngpio)
+		goto fail;
+	gpio_ensure_requested(desc);
+
+	/* now we know the gpio is valid and chip won't vanish */
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	might_sleep_if(extra_checks && chip->can_sleep);
+
+	status = chip->direction_output(chip, gpio, value);
+	if (status == 0)
+		set_bit(FLAG_IS_OUT, &desc->flags);
+	return status;
+fail:
+	spin_unlock_irqrestore(&gpio_lock, flags);
+	if (status)
+		pr_debug("%s: gpio-%d status %d\n",
+			__FUNCTION__, gpio, status);
+	return status;
+}
+EXPORT_SYMBOL_GPL(gpio_direction_output);
+
+
+/* I/O calls are only valid after configuration completed; the relevant
+ * "is this a valid GPIO" error checks should already have been done.
+ *
+ * "Get" operations are often inlinable as reading a pin value register,
+ * and masking the relevant bit in that register.
+ *
+ * When "set" operations are inlinable, they involve writing that mask to
+ * one register to set a low value, or a different register to set it high.
+ * Otherwise locking is needed, so there may be little value to inlining.
+ *
+ *------------------------------------------------------------------------
+ *
+ * IMPORTANT!!!  The hot paths -- get/set value -- assume that callers
+ * have requested the GPIO.  That can include implicit requesting by
+ * a direction setting call.  Marking a gpio as requested locks its chip
+ * in memory, guaranteeing that these table lookups need no more locking
+ * and that gpiochip_remove() will fail.
+ *
+ * REVISIT when debugging, consider adding some instrumentation to ensure
+ * that the GPIO was actually requested.
+ */
+
+/**
+ * __gpio_get_value() - return a gpio's value
+ * @gpio: gpio whose value will be returned
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_get_value().
+ * It returns the zero or nonzero value provided by the associated
+ * gpio_chip.get() method; or zero if no such method is provided.
+ */
+int __gpio_get_value(unsigned gpio)
+{
+	struct gpio_chip	*chip;
+
+	chip = gpio_to_chip(gpio);
+	WARN_ON(extra_checks && chip->can_sleep);
+	return chip->get ? chip->get(chip, gpio - chip->base) : 0;
+}
+EXPORT_SYMBOL_GPL(__gpio_get_value);
+
+/**
+ * __gpio_set_value() - assign a gpio's value
+ * @gpio: gpio whose value will be assigned
+ * @value: value to assign
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_set_value().
+ * It invokes the associated gpio_chip.set() method.
+ */
+void __gpio_set_value(unsigned gpio, int value)
+{
+	struct gpio_chip	*chip;
+
+	chip = gpio_to_chip(gpio);
+	WARN_ON(extra_checks && chip->can_sleep);
+	chip->set(chip, gpio - chip->base, value);
+}
+EXPORT_SYMBOL_GPL(__gpio_set_value);
+
+/**
+ * __gpio_cansleep() - report whether gpio value access will sleep
+ * @gpio: gpio in question
+ * Context: any
+ *
+ * This is used directly or indirectly to implement gpio_cansleep().  It
+ * returns nonzero if access reading or writing the GPIO value can sleep.
+ */
+int __gpio_cansleep(unsigned gpio)
+{
+	struct gpio_chip	*chip;
+
+	/* only call this on GPIOs that are valid! */
+	chip = gpio_to_chip(gpio);
+
+	return chip->can_sleep;
+}
+EXPORT_SYMBOL_GPL(__gpio_cansleep);
+
+
+
+/* There's no value in making it easy to inline GPIO calls that may sleep.
+ * Common examples include ones connected to I2C or SPI chips.
+ */
+
+int gpio_get_value_cansleep(unsigned gpio)
+{
+	struct gpio_chip	*chip;
+
+	might_sleep_if(extra_checks);
+	chip = gpio_to_chip(gpio);
+	return chip->get(chip, gpio - chip->base);
+}
+EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
+
+void gpio_set_value_cansleep(unsigned gpio, int value)
+{
+	struct gpio_chip	*chip;
+
+	might_sleep_if(extra_checks);
+	chip = gpio_to_chip(gpio);
+	chip->set(chip, gpio - chip->base, value);
+}
+EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
+
+
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+
+static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
+{
+	unsigned		i;
+	unsigned		gpio = chip->base;
+	struct gpio_desc	*gdesc = &gpio_desc[gpio];
+	int			is_out;
+
+	for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
+		if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
+			continue;
+
+		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
+		seq_printf(s, " gpio-%-3d (%-12s) %s %s",
+			gpio, gdesc->label,
+			is_out ? "out" : "in ",
+			chip->get
+				? (chip->get(chip, i) ? "hi" : "lo")
+				: "?  ");
+
+		if (!is_out) {
+			int		irq = gpio_to_irq(gpio);
+			struct irq_desc	*desc = irq_desc + irq;
+
+			/* This races with request_irq(), set_irq_type(),
+			 * and set_irq_wake() ... but those are "rare".
+			 *
+			 * More significantly, trigger type flags aren't
+			 * currently maintained by genirq.
+			 */
+			if (irq >= 0 && desc->action) {
+				char *trigger;
+
+				switch (desc->status & IRQ_TYPE_SENSE_MASK) {
+				case IRQ_TYPE_NONE:
+					trigger = "(default)";
+					break;
+				case IRQ_TYPE_EDGE_FALLING:
+					trigger = "edge-falling";
+					break;
+				case IRQ_TYPE_EDGE_RISING:
+					trigger = "edge-rising";
+					break;
+				case IRQ_TYPE_EDGE_BOTH:
+					trigger = "edge-both";
+					break;
+				case IRQ_TYPE_LEVEL_HIGH:
+					trigger = "level-high";
+					break;
+				case IRQ_TYPE_LEVEL_LOW:
+					trigger = "level-low";
+					break;
+				default:
+					trigger = "?trigger?";
+					break;
+				}
+
+				seq_printf(s, " irq-%d %s%s",
+					irq, trigger,
+					(desc->status & IRQ_WAKEUP)
+						? " wakeup" : "");
+			}
+		}
+
+		seq_printf(s, "\n");
+	}
+}
+
+static int gpiolib_show(struct seq_file *s, void *unused)
+{
+	struct gpio_chip	*chip = NULL;
+	unsigned		gpio;
+	int			started = 0;
+
+	/* REVISIT this isn't locked against gpio_chip removal ... */
+
+	for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
+		if (chip == gpio_desc[gpio].chip)
+			continue;
+		chip = gpio_desc[gpio].chip;
+		if (!chip)
+			continue;
+
+		seq_printf(s, "%sGPIOs %d-%d, %s%s:\n",
+				started ? "\n" : "",
+				chip->base, chip->base + chip->ngpio - 1,
+				chip->label ? : "generic",
+				chip->can_sleep ? ", can sleep" : "");
+		started = 1;
+		if (chip->dbg_show)
+			chip->dbg_show(s, chip);
+		else
+			gpiolib_dbg_show(s, chip);
+	}
+	return 0;
+}
+
+static int gpiolib_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, gpiolib_show, NULL);
+}
+
+static struct file_operations gpiolib_operations = {
+	.open		= gpiolib_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init gpiolib_debugfs_init(void)
+{
+	/* /sys/kernel/debug/gpio */
+	(void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
+				NULL, NULL, &gpiolib_operations);
+	return 0;
+}
+subsys_initcall(gpiolib_debugfs_init);
+
+#endif	/* DEBUG_FS */
--- at91.orig/include/asm-generic/gpio.h	2008-01-05 12:00:41.000000000 -0800
+++ at91/include/asm-generic/gpio.h	2008-01-05 12:01:01.000000000 -0800
@@ -1,6 +1,102 @@
 #ifndef _ASM_GENERIC_GPIO_H
 #define _ASM_GENERIC_GPIO_H
 
+#ifdef CONFIG_HAVE_GPIO_LIB
+
+/* Platforms may implement their GPIO interface with library code,
+ * at a small performance cost for non-inlined operations and some
+ * extra memory (for code and for per-GPIO table entries).
+ *
+ * While the GPIO programming interface defines valid GPIO numbers
+ * to be in the range 0..MAX_INT, this library restricts them to the
+ * smaller range 0..ARCH_NR_GPIOS.
+ */
+
+#ifndef ARCH_NR_GPIOS
+#define ARCH_NR_GPIOS		256
+#endif
+
+struct seq_file;
+
+/**
+ * struct gpio_chip - abstract a GPIO controller
+ * @label: for diagnostics
+ * @direction_input: configures signal "offset" as input, or returns error
+ * @get: returns value for signal "offset"; for output signals this
+ *	returns either the value actually sensed, or zero
+ * @direction_output: configures signal "offset" as output, or returns error
+ * @set: assigns output value for signal "offset"
+ * @dbg_show: optional routine to show contents in debugfs; default code
+ *	will be used when this is omitted, but custom code can show extra
+ *	state (such as pullup/pulldown configuration).
+ * @base: identifies the first GPIO number handled by this chip; or, if
+ *	negative during registration, requests dynamic ID allocation.
+ * @ngpio: the number of GPIOs handled by this controller; the last GPIO
+ *	handled is (base + ngpio - 1).
+ * @can_sleep: flag must be set iff get()/set() methods sleep, as they
+ *	must while accessing GPIO expander chips over I2C or SPI
+ *
+ * A gpio_chip can help platforms abstract various sources of GPIOs so
+ * they can all be accessed through a common programing interface.
+ * Example sources would be SOC controllers, FPGAs, multifunction
+ * chips, dedicated GPIO expanders, and so on.
+ *
+ * Each chip controls a number of signals, identified in method calls
+ * by "offset" values in the range 0..(@ngpio - 1).  When those signals
+ * are referenced through calls like gpio_get_value(gpio), the offset
+ * is calculated by subtracting @base from the gpio number.
+ */
+struct gpio_chip {
+	char			*label;
+
+	int			(*direction_input)(struct gpio_chip *chip,
+						unsigned offset);
+	int			(*get)(struct gpio_chip *chip,
+						unsigned offset);
+	int			(*direction_output)(struct gpio_chip *chip,
+						unsigned offset, int value);
+	void			(*set)(struct gpio_chip *chip,
+						unsigned offset, int value);
+	void			(*dbg_show)(struct seq_file *s,
+						struct gpio_chip *chip);
+	int			base;
+	u16			ngpio;
+	unsigned		can_sleep:1;
+};
+
+extern const char *gpiochip_is_requested(struct gpio_chip *chip,
+			unsigned offset);
+
+/* add/remove chips */
+extern int gpiochip_add(struct gpio_chip *chip);
+extern int __must_check gpiochip_remove(struct gpio_chip *chip);
+
+
+/* Always use the library code for GPIO management calls,
+ * or when sleeping may be involved.
+ */
+extern int gpio_request(unsigned gpio, const char *label);
+extern void gpio_free(unsigned gpio);
+
+extern int gpio_direction_input(unsigned gpio);
+extern int gpio_direction_output(unsigned gpio, int value);
+
+extern int gpio_get_value_cansleep(unsigned gpio);
+extern void gpio_set_value_cansleep(unsigned gpio, int value);
+
+
+/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
+ * the GPIO is constant and refers to some always-present controller,
+ * giving direct access to chip registers and tight bitbanging loops.
+ */
+extern int __gpio_get_value(unsigned gpio);
+extern void __gpio_set_value(unsigned gpio, int value);
+
+extern int __gpio_cansleep(unsigned gpio);
+
+
+#else
+
 /* platforms that don't directly support access to GPIOs through I2C, SPI,
  * or other blocking infrastructure can use these wrappers.
  */
@@ -22,4 +118,6 @@ static inline void gpio_set_value_cansle
 	gpio_set_value(gpio, value);
 }
 
+#endif
+
 #endif /* _ASM_GENERIC_GPIO_H */

[patch 2.6.24-rc6-mm 3/9] gpiolib: update Documentation/gpio.txt

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Update Documentation/gpio.txt, primarily to include the new
optional "gpiolib" implementation infrastructure.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 Documentation/gpio.txt |  133 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 121 insertions(+), 12 deletions(-)

--- at91.orig/Documentation/gpio.txt
+++ at91/Documentation/gpio.txt
@@ -32,7 +32,7 @@ The exact capabilities of GPIOs vary bet
   - Input values are likewise readable (1, 0).  Some chips support readback
     of pins configured as "output", which is very useful in such "wire-OR"
     cases (to support bidirectional signaling).  GPIO controllers may have
-    input de-glitch logic, sometimes with software controls.
+    input de-glitch/debounce logic, sometimes with software controls.
 
   - Inputs can often be used as IRQ signals, often edge triggered but
     sometimes level triggered.  Such IRQs may be configurable as system
@@ -60,10 +60,13 @@ used on a board that's wired differently
 functionality can be very portable.  Other features are platform-specific,
 and that can be critical for glue logic.
 
-Plus, this doesn't define an implementation framework, just an interface.
+Plus, this doesn't require any implementation framework, just an interface.
 One platform might implement it as simple inline functions accessing chip
 registers; another might implement it by delegating through abstractions
-used for several very different kinds of GPIO controller.
+used for several very different kinds of GPIO controller.  (There is some
+optional code supporting such an implementation strategy, described later
+in this document, but drivers acting as clients to the GPIO interface must
+not care how it's implemented.)
 
 That said, if the convention is supported on their platform, drivers should
 use it when possible.  Platforms should declare GENERIC_GPIO support in
@@ -121,6 +124,11 @@ before tasking is enabled, as part of ea
 For output GPIOs, the value provided becomes the initial output value.
 This helps avoid signal glitching during system startup.
 
+For compatibility with legacy interfaces to GPIOs, setting the direction
+of a GPIO implicitly requests that GPIO (see below) if it has not been
+requested already.  That compatibility may be removed in the future;
+explicitly requesting GPIOs is strongly preferred.
+
 Setting the direction can fail if the GPIO number is invalid, or when
 that particular GPIO can't be used in that mode.  It's generally a bad
 idea to rely on boot firmware to have set the direction correctly, since
@@ -133,6 +141,7 @@ Spinlock-Safe GPIO access
 -------------------------
 Most GPIO controllers can be accessed with memory read/write instructions.
 That doesn't need to sleep, and can safely be done from inside IRQ handlers.
+(That includes hardirq contexts on RT kernels.)
 
 Use these calls to access such GPIOs:
 
@@ -145,7 +154,7 @@ Use these calls to access such GPIOs:
 The values are boolean, zero for low, nonzero for high.  When reading the
 value of an output pin, the value returned should be what's seen on the
 pin ... that won't always match the specified output value, because of
-issues including wire-OR and output latencies.
+issues including open-drain signaling and output latencies.
 
 The get/set calls have no error returns because "invalid GPIO" should have
 been reported earlier from gpio_direction_*().  However, note that not all
@@ -170,7 +179,8 @@ get to the head of a queue to transmit a
 This requires sleeping, which can't be done from inside IRQ handlers.
 
 Platforms that support this type of GPIO distinguish them from other GPIOs
-by returning nonzero from this call:
+by returning nonzero from this call (which requires a valid GPIO number,
+either explicitly or implicitly requested):
 
 	int gpio_cansleep(unsigned gpio);
 
@@ -209,8 +219,11 @@ before tasking is enabled, as part of ea
 These calls serve two basic purposes.  One is marking the signals which
 are actually in use as GPIOs, for better diagnostics; systems may have
 several hundred potential GPIOs, but often only a dozen are used on any
-given board.  Another is to catch conflicts between drivers, reporting
-errors when drivers wrongly think they have exclusive use of that signal.
+given board.  Another is to catch conflicts, identifying errors when
+(a) two or more drivers wrongly think they have exclusive use of that
+signal, or (b) something wrongly believes it's safe to remove drivers
+needed to manage a signal that's in active use.  That is, requesting a
+GPIO can serve as a kind of lock.
 
 These two calls are optional because not not all current Linux platforms
 offer such functionality in their GPIO support; a valid implementation
@@ -223,6 +236,9 @@ Note that requesting a GPIO does NOT cau
 way; it just marks that GPIO as in use.  Separate code must handle any
 pin setup (e.g. controlling which pin the GPIO uses, pullup/pulldown).
 
+Also note that it's your responsibility to have stopped using a GPIO
+before you free it.
+
 
 GPIOs mapped to IRQs
 --------------------
@@ -238,7 +254,7 @@ map between them using calls like:
 
 Those return either the corresponding number in the other namespace, or
 else a negative errno code if the mapping can't be done.  (For example,
-some GPIOs can't used as IRQs.)  It is an unchecked error to use a GPIO
+some GPIOs can't be used as IRQs.)  It is an unchecked error to use a GPIO
 number that wasn't set up as an input using gpio_direction_input(), or
 to use an IRQ number that didn't originally come from gpio_to_irq().
 
@@ -299,17 +315,110 @@ Related to multiplexing is configuration
 pulldowns integrated on some platforms.  Not all platforms support them,
 or support them in the same way; and any given board might use external
 pullups (or pulldowns) so that the on-chip ones should not be used.
+(When a circuit needs 5 kOhm, on-chip 100 kOhm resistors won't do.)
 
 There are other system-specific mechanisms that are not specified here,
 like the aforementioned options for input de-glitching and wire-OR output.
 Hardware may support reading or writing GPIOs in gangs, but that's usually
 configuration dependent:  for GPIOs sharing the same bank.  (GPIOs are
 commonly grouped in banks of 16 or 32, with a given SOC having several such
-banks.)  Some systems can trigger IRQs from output GPIOs.  Code relying on
-such mechanisms will necessarily be nonportable.
+banks.)  Some systems can trigger IRQs from output GPIOs, or read values
+from pins not managed as GPIOs.  Code relying on such mechanisms will
+necessarily be nonportable.
 
-Dynamic definition of GPIOs is not currently supported; for example, as
+Dynamic definition of GPIOs is not currently standard; for example, as
 a side effect of configuring an add-on board with some GPIO expanders.
 
 These calls are purely for kernel space, but a userspace API could be built
-on top of it.
+on top of them.
+
+
+GPIO implementor's framework (OPTIONAL)
+=======================================
+As noted earlier, there is an optional implementation framework making it
+easier for platforms to support different kinds of GPIO controller using
+the same programming interface.
+
+As a debugging aid, if debugfs is available a /sys/kernel/debug/gpio file
+will be found there.  That will list all the controllers registered through
+this framework, and the state of the GPIOs currently in use.
+
+
+Controller Drivers: gpio_chip
+-----------------------------
+In this framework each GPIO controller is packaged as a "struct gpio_chip"
+with information common to each controller of that type:
+
+ - methods to establish GPIO direction
+ - methods used to access GPIO values
+ - flag saying whether calls to its methods may sleep
+ - optional debugfs dump method (showing extra state like pullup config)
+ - label for diagnostics
+
+There is also per-instance data, which may come from device.platform_data:
+the number of its first GPIO, and how many GPIOs it exposes.
+
+The code implementing a gpio_chip should support multiple instances of the
+controller, possibly using the driver model.  That code will configure each
+gpio_chip and issue gpiochip_add().  Removing a GPIO controller should be
+rare; use gpiochip_remove() when it is unavoidable.
+
+Most often a gpio_chip is part of an instance-specific structure with state
+not exposed by the GPIO interfaces, such as addressing, power management,
+and more.  Chips such as codecs will have complex non-GPIO state,
+
+Any debugfs dump method should normally ignore signals which haven't been
+requested as GPIOs.  They can use gpiochip_is_requested(), which returns
+either NULL or the label associated with that GPIO when it was requested.
+
+
+Platform Support
+----------------
+To support this framework, a platform's Kconfig will "select GPIO_LIB" and
+arrange that its <asm/gpio.h> then include <asm-generic/gpio.h> and define
+three functions: gpio_get_value(), gpio_set_value(), and gpio_cansleep().
+They may also want to provide a custom value for ARCH_NR_GPIOS.
+
+Trivial implementations of those functions can directly use framework
+code, which always dispatches through the gpio_chip:
+
+  #define gpio_get_value	__gpio_get_value
+  #define gpio_set_value	__gpio_set_value
+  #define gpio_cansleep		__gpio_cansleep
+
+Fancier implementations could instead define those as inline functions with
+logic optimizing access to specific SOC-based GPIOs.  For example, if the
+referenced GPIO is the constant "12", getting or setting its value could
+cost as little as two or three instructions, never sleeping.  When such an
+optimization is not possible those calls must delegate to the framework
+code, costing at least a few dozen instructions.  For bitbanged I/O, such
+instruction savings can be significant.
+
+For SOCs, platform-specific code defines and registers gpio_chip instances
+for each bank of on-chip GPIOs.  Those GPIOs should be numbered/labeled to
+match chip vendor documentation, and directly match board schematics.  They
+may well start at zero and go up to a platform-specific limit.  Such GPIOs
+are normally integrated into platform initialization to make them always be
+available, from arch_initcall() or earlier; they can often serve as IRQs.
+
+
+Board Support
+-------------
+For external GPIO controllers -- such as I2C or SPI expanders, ASICs, multi
+function devices, FPGAs or CPLDs -- most often board-specific code handles
+registering controller devices and ensures that their drivers know what GPIO
+numbers to use with gpiochip_add().  Their numbers often start right after
+platform-specific GPIOs.
+
+For example, board setup code could create structures identifying the range
+of GPIOs that chip will expose, and passes them to each GPIO expander chip
+using platform_data.  Then the chip driver's probe() routine could pass that
+data to gpiochip_add().
+
+Initialization order can be important.  For example, when a device relies on
+an I2C-based GPIO, its probe() routine should only be called after that GPIO
+becomes available.  That may mean the device should not be registered until
+calls for that GPIO can work.  One way to address such dependencies is for
+such gpio_chip controllers to provide setup() and teardown() callbacks to
+board specific code; those board specific callbacks would register devices
+once all the necessary resources are available.

Re: [patch 2.6.24-rc6-mm 3/9] gpiolib: update Documentation/gpio.txt

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Update Documentation/gpio.txt, primarily to include the new
"gpiolib" infrastructure.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
Incorporates cleanup as suggested by Sam Ravnborg.

 Documentation/gpio.txt |  133 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 121 insertions(+), 12 deletions(-)

--- at91.orig/Documentation/gpio.txt	2008-01-05 11:59:55.000000000 -0800
+++ at91/Documentation/gpio.txt	2008-01-05 12:01:07.000000000 -0800
@@ -32,7 +32,7 @@ The exact capabilities of GPIOs vary bet
   - Input values are likewise readable (1, 0).  Some chips support readback
     of pins configured as "output", which is very useful in such "wire-OR"
     cases (to support bidirectional signaling).  GPIO controllers may have
-    input de-glitch logic, sometimes with software controls.
+    input de-glitch/debounce logic, sometimes with software controls.
 
   - Inputs can often be used as IRQ signals, often edge triggered but
     sometimes level triggered.  Such IRQs may be configurable as system
@@ -60,10 +60,13 @@ used on a board that's wired differently
 functionality can be very portable.  Other features are platform-specific,
 and that can be critical for glue logic.
 
-Plus, this doesn't define an implementation framework, just an interface.
+Plus, this doesn't require any implementation framework, just an interface.
 One platform might implement it as simple inline functions accessing chip
 registers; another might implement it by delegating through abstractions
-used for several very different kinds of GPIO controller.
+used for several very different kinds of GPIO controller.  (There is some
+optional code supporting such an implementation strategy, described later
+in this document, but drivers acting as clients to the GPIO interface must
+not care how it's implemented.)
 
 That said, if the convention is supported on their platform, drivers should
 use it when possible.  Platforms should declare GENERIC_GPIO support in
@@ -121,6 +124,11 @@ before tasking is enabled, as part of ea
 For output GPIOs, the value provided becomes the initial output value.
 This helps avoid signal glitching during system startup.
 
+For compatibility with legacy interfaces to GPIOs, setting the direction
+of a GPIO implicitly requests that GPIO (see below) if it has not been
+requested already.  That compatibility may be removed in the future;
+explicitly requesting GPIOs is strongly preferred.
+
 Setting the direction can fail if the GPIO number is invalid, or when
 that particular GPIO can't be used in that mode.  It's generally a bad
 idea to rely on boot firmware to have set the direction correctly, since
@@ -133,6 +141,7 @@ Spinlock-Safe GPIO access
 -------------------------
 Most GPIO controllers can be accessed with memory read/write instructions.
 That doesn't need to sleep, and can safely be done from inside IRQ handlers.
+(That includes hardirq contexts on RT kernels.)
 
 Use these calls to access such GPIOs:
 
@@ -145,7 +154,7 @@ Use these calls to access such GPIOs:
 The values are boolean, zero for low, nonzero for high.  When reading the
 value of an output pin, the value returned should be what's seen on the
 pin ... that won't always match the specified output value, because of
-issues including wire-OR and output latencies.
+issues including open-drain signaling and output latencies.
 
 The get/set calls have no error returns because "invalid GPIO" should have
 been reported earlier from gpio_direction_*().  However, note that not all
@@ -170,7 +179,8 @@ get to the head of a queue to transmit a
 This requires sleeping, which can't be done from inside IRQ handlers.
 
 Platforms that support this type of GPIO distinguish them from other GPIOs
-by returning nonzero from this call:
+by returning nonzero from this call (which requires a valid GPIO number,
+either explicitly or implicitly requested):
 
 	int gpio_cansleep(unsigned gpio);
 
@@ -209,8 +219,11 @@ before tasking is enabled, as part of ea
 These calls serve two basic purposes.  One is marking the signals which
 are actually in use as GPIOs, for better diagnostics; systems may have
 several hundred potential GPIOs, but often only a dozen are used on any
-given board.  Another is to catch conflicts between drivers, reporting
-errors when drivers wrongly think they have exclusive use of that signal.
+given board.  Another is to catch conflicts, identifying errors when
+(a) two or more drivers wrongly think they have exclusive use of that
+signal, or (b) something wrongly believes it's safe to remove drivers
+needed to manage a signal that's in active use.  That is, requesting a
+GPIO can serve as a kind of lock.
 
 These two calls are optional because not not all current Linux platforms
 offer such functionality in their GPIO support; a valid implementation
@@ -223,6 +236,9 @@ Note that requesting a GPIO does NOT cau
 way; it just marks that GPIO as in use.  Separate code must handle any
 pin setup (e.g. controlling which pin the GPIO uses, pullup/pulldown).
 
+Also note that it's your responsibility to have stopped using a GPIO
+before you free it.
+
 
 GPIOs mapped to IRQs
 --------------------
@@ -238,7 +254,7 @@ map between them using calls like:
 
 Those return either the corresponding number in the other namespace, or
 else a negative errno code if the mapping can't be done.  (For example,
-some GPIOs can't used as IRQs.)  It is an unchecked error to use a GPIO
+some GPIOs can't be used as IRQs.)  It is an unchecked error to use a GPIO
 number that wasn't set up as an input using gpio_direction_input(), or
 to use an IRQ number that didn't originally come from gpio_to_irq().
 
@@ -299,17 +315,110 @@ Related to multiplexing is configuration
 pulldowns integrated on some platforms.  Not all platforms support them,
 or support them in the same way; and any given board might use external
 pullups (or pulldowns) so that the on-chip ones should not be used.
+(When a circuit needs 5 kOhm, on-chip 100 kOhm resistors won't do.)
 
 There are other system-specific mechanisms that are not specified here,
 like the aforementioned options for input de-glitching and wire-OR output.
 Hardware may support reading or writing GPIOs in gangs, but that's usually
 configuration dependent:  for GPIOs sharing the same bank.  (GPIOs are
 commonly grouped in banks of 16 or 32, with a given SOC having several such
-banks.)  Some systems can trigger IRQs from output GPIOs.  Code relying on
-such mechanisms will necessarily be nonportable.
+banks.)  Some systems can trigger IRQs from output GPIOs, or read values
+from pins not managed as GPIOs.  Code relying on such mechanisms will
+necessarily be nonportable.
 
-Dynamic definition of GPIOs is not currently supported; for example, as
+Dynamic definition of GPIOs is not currently standard; for example, as
 a side effect of configuring an add-on board with some GPIO expanders.
 
 These calls are purely for kernel space, but a userspace API could be built
-on top of it.
+on top of them.
+
+
+GPIO implementor's framework (OPTIONAL)
+=======================================
+As noted earlier, there is an optional implementation framework making it
+easier for platforms to support different kinds of GPIO controller using
+the same programming interface.
+
+As a debugging aid, if debugfs is available a /sys/kernel/debug/gpio file
+will be found there.  That will list all the controllers registered through
+this framework, and the state of the GPIOs currently in use.
+
+
+Controller Drivers: gpio_chip
+-----------------------------
+In this framework each GPIO controller is packaged as a "struct gpio_chip"
+with information common to each controller of that type:
+
+ - methods to establish GPIO direction
+ - methods used to access GPIO values
+ - flag saying whether calls to its methods may sleep
+ - optional debugfs dump method (showing extra state like pullup config)
+ - label for diagnostics
+
+There is also per-instance data, which may come from device.platform_data:
+the number of its first GPIO, and how many GPIOs it exposes.
+
+The code implementing a gpio_chip should support multiple instances of the
+controller, possibly using the driver model.  That code will configure each
+gpio_chip and issue gpiochip_add().  Removing a GPIO controller should be
+rare; use gpiochip_remove() when it is unavoidable.
+
+Most often a gpio_chip is part of an instance-specific structure with state
+not exposed by the GPIO interfaces, such as addressing, power management,
+and more.  Chips such as codecs will have complex non-GPIO state,
+
+Any debugfs dump method should normally ignore signals which haven't been
+requested as GPIOs.  They can use gpiochip_is_requested(), which returns
+either NULL or the label associated with that GPIO when it was requested.
+
+
+Platform Support
+----------------
+To support this framework, a platform's Kconfig will "select HAVE_GPIO_LIB"
+and arrange that its <asm/gpio.h> includes <asm-generic/gpio.h> and defines
+three functions: gpio_get_value(), gpio_set_value(), and gpio_cansleep().
+They may also want to provide a custom value for ARCH_NR_GPIOS.
+
+Trivial implementations of those functions can directly use framework
+code, which always dispatches through the gpio_chip:
+
+  #define gpio_get_value	__gpio_get_value
+  #define gpio_set_value	__gpio_set_value
+  #define gpio_cansleep		__gpio_cansleep
+
+Fancier implementations could instead define those as inline functions with
+logic optimizing access to specific SOC-based GPIOs.  For example, if the
+referenced GPIO is the constant "12", getting or setting its value could
+cost as little as two or three instructions, never sleeping.  When such an
+optimization is not possible those calls must delegate to the framework
+code, costing at least a few dozen instructions.  For bitbanged I/O, such
+instruction savings can be significant.
+
+For SOCs, platform-specific code defines and registers gpio_chip instances
+for each bank of on-chip GPIOs.  Those GPIOs should be numbered/labeled to
+match chip vendor documentation, and directly match board schematics.  They
+may well start at zero and go up to a platform-specific limit.  Such GPIOs
+are normally integrated into platform initialization to make them always be
+available, from arch_initcall() or earlier; they can often serve as IRQs.
+
+
+Board Support
+-------------
+For external GPIO controllers -- such as I2C or SPI expanders, ASICs, multi
+function devices, FPGAs or CPLDs -- most often board-specific code handles
+registering controller devices and ensures that their drivers know what GPIO
+numbers to use with gpiochip_add().  Their numbers often start right after
+platform-specific GPIOs.
+
+For example, board setup code could create structures identifying the range
+of GPIOs that chip will expose, and passes them to each GPIO expander chip
+using platform_data.  Then the chip driver's probe() routine could pass that
+data to gpiochip_add().
+
+Initialization order can be important.  For example, when a device relies on
+an I2C-based GPIO, its probe() routine should only be called after that GPIO
+becomes available.  That may mean the device should not be registered until
+calls for that GPIO can work.  One way to address such dependencies is for
+such gpio_chip controllers to provide setup() and teardown() callbacks to
+board specific code; those board specific callbacks would register devices
+once all the necessary resources are available.

[patch 2.6.24-rc6-mm 4/9] gpiolib: avr32 at32ap platform support

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Teach AVR32 to use the "GPIO Library" when exposing its GPIOs, so that
signals on external chips (like GPIO expanders) can easily be used.

This mostly just reorganizes some existing logic, with two minor changes
in behavior:

 - The PSR registers are used instead of the previous "gpio_mask" values,
   matching AT91 behavior and removing some duplication between that role
   and that of "pinmux_mask".

 - NR_IRQs grew to acommodate a bank of external GPIOs.  Eventually this
   number should probably become a board-specific config option.

There's a debugfs dump of status for the built-in GPIOs, showing which
pins have deglitching, pullups, or open drain drive enabled, as well as
the ID string used when requesting each IRQ.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
---
 arch/avr32/Kconfig                         |    1 
 arch/avr32/mach-at32ap/pio.c               |  172 +++++++++++++++--------------
 arch/avr32/mach-at32ap/pio.h               |    2 
 include/asm-avr32/arch-at32ap/at32ap7000.h |    2 
 include/asm-avr32/arch-at32ap/gpio.h       |   36 ++++--
 include/asm-avr32/arch-at32ap/irq.h        |    4 
 6 files changed, 122 insertions(+), 95 deletions(-)

--- at91.orig/arch/avr32/Kconfig
+++ at91/arch/avr32/Kconfig
@@ -80,6 +80,7 @@ config PLATFORM_AT32AP
 	select SUBARCH_AVR32B
 	select MMU
 	select PERFORMANCE_COUNTERS
+	select GPIO_LIB
 
 choice
 	prompt "AVR32 CPU type"
--- at91.orig/arch/avr32/mach-at32ap/pio.c
+++ at91/arch/avr32/mach-at32ap/pio.c
@@ -24,11 +24,11 @@
 #define MAX_NR_PIO_DEVICES		8
 
 struct pio_device {
+	struct gpio_chip chip;
 	void __iomem *regs;
 	const struct platform_device *pdev;
 	struct clk *clk;
 	u32 pinmux_mask;
-	u32 gpio_mask;
 	char name[8];
 };
 
@@ -64,7 +64,8 @@ void __init at32_select_periph(unsigned 
 		goto fail;
 	}
 
-	if (unlikely(test_and_set_bit(pin_index, &pio->pinmux_mask))) {
+	if (unlikely(test_and_set_bit(pin_index, &pio->pinmux_mask)
+			 || gpiochip_is_requested(&pio->chip, pin_index))) {
 		printk("%s: pin %u is busy\n", pio->name, pin_index);
 		goto fail;
 	}
@@ -79,9 +80,6 @@ void __init at32_select_periph(unsigned 
 	if (!(flags & AT32_GPIOF_PULLUP))
 		pio_writel(pio, PUDR, mask);
 
-	/* gpio_request NOT allowed */
-	set_bit(pin_index, &pio->gpio_mask);
-
 	return;
 
 fail:
@@ -130,9 +128,6 @@ void __init at32_select_gpio(unsigned in
 
 	pio_writel(pio, PER, mask);
 
-	/* gpio_request now allowed */
-	clear_bit(pin_index, &pio->gpio_mask);
-
 	return;
 
 fail:
@@ -166,96 +161,50 @@ fail:
 
 /* GPIO API */
 
-int gpio_request(unsigned int gpio, const char *label)
+static int direction_input(struct gpio_chip *chip, unsigned offset)
 {
-	struct pio_device *pio;
-	unsigned int pin;
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32 mask = 1 << offset;
 
-	pio = gpio_to_pio(gpio);
-	if (!pio)
-		return -ENODEV;
-
-	pin = gpio & 0x1f;
-	if (test_and_set_bit(pin, &pio->gpio_mask))
-		return -EBUSY;
+	if (!(pio_readl(pio, PSR) & mask))
+		return -EINVAL;
 
+	pio_writel(pio, ODR, mask);
 	return 0;
 }
-EXPORT_SYMBOL(gpio_request);
 
-void gpio_free(unsigned int gpio)
+static int gpio_get(struct gpio_chip *chip, unsigned offset)
 {
-	struct pio_device *pio;
-	unsigned int pin;
-
-	pio = gpio_to_pio(gpio);
-	if (!pio) {
-		printk(KERN_ERR
-		       "gpio: attempted to free invalid pin %u\n", gpio);
-		return;
-	}
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
 
-	pin = gpio & 0x1f;
-	if (!test_and_clear_bit(pin, &pio->gpio_mask))
-		printk(KERN_ERR "gpio: freeing free or non-gpio pin %s-%u\n",
-		       pio->name, pin);
+	return (pio_readl(pio, PDSR) >> offset) & 1;
 }
-EXPORT_SYMBOL(gpio_free);
 
-int gpio_direction_input(unsigned int gpio)
-{
-	struct pio_device *pio;
-	unsigned int pin;
-
-	pio = gpio_to_pio(gpio);
-	if (!pio)
-		return -ENODEV;
+static void gpio_set(struct gpio_chip *chip, unsigned offset, int value);
 
-	pin = gpio & 0x1f;
-	pio_writel(pio, ODR, 1 << pin);
-
-	return 0;
-}
-EXPORT_SYMBOL(gpio_direction_input);
-
-int gpio_direction_output(unsigned int gpio, int value)
+static int direction_output(struct gpio_chip *chip, unsigned offset, int value)
 {
-	struct pio_device *pio;
-	unsigned int pin;
-
-	pio = gpio_to_pio(gpio);
-	if (!pio)
-		return -ENODEV;
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32 mask = 1 << offset;
 
-	gpio_set_value(gpio, value);
-
-	pin = gpio & 0x1f;
-	pio_writel(pio, OER, 1 << pin);
+	if (!(pio_readl(pio, PSR) & mask))
+		return -EINVAL;
 
+	gpio_set(chip, offset, value);
+	pio_writel(pio, OER, mask);
 	return 0;
 }
-EXPORT_SYMBOL(gpio_direction_output);
 
-int gpio_get_value(unsigned int gpio)
+static void gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 {
-	struct pio_device *pio = &pio_dev[gpio >> 5];
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32 mask = 1 << offset;
 
-	return (pio_readl(pio, PDSR) >> (gpio & 0x1f)) & 1;
-}
-EXPORT_SYMBOL(gpio_get_value);
-
-void gpio_set_value(unsigned int gpio, int value)
-{
-	struct pio_device *pio = &pio_dev[gpio >> 5];
-	u32 mask;
-
-	mask = 1 << (gpio & 0x1f);
 	if (value)
 		pio_writel(pio, SODR, mask);
 	else
 		pio_writel(pio, CODR, mask);
 }
-EXPORT_SYMBOL(gpio_set_value);
 
 /*--------------------------------------------------------------------------*/
 
@@ -339,6 +288,63 @@ gpio_irq_setup(struct pio_device *pio, i
 
 /*--------------------------------------------------------------------------*/
 
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/seq_file.h>
+
+/*
+ * This shows more info than the generic gpio dump code:
+ * pullups, deglitching, open drain drive.
+ */
+static void pio_bank_show(struct seq_file *s, struct gpio_chip *chip)
+{
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32			psr, osr, imr, pdsr, pusr, ifsr, mdsr;
+	unsigned		i;
+	u32			mask;
+	char			bank;
+
+	psr = pio_readl(pio, PSR);
+	osr = pio_readl(pio, OSR);
+	imr = pio_readl(pio, IMR);
+	pdsr = pio_readl(pio, PDSR);
+	pusr = pio_readl(pio, PUSR);
+	ifsr = pio_readl(pio, IFSR);
+	mdsr = pio_readl(pio, MDSR);
+
+	bank = 'A' + pio->pdev->id;
+
+	for (i = 0, mask = 1; i < 32; i++, mask <<= 1) {
+		const char *label;
+
+		label = gpiochip_is_requested(chip, i);
+		if (!label)
+			continue;
+
+		seq_printf(s, " gpio-%-3d P%c%-2d (%-12s) %s %s %s",
+			chip->base + i, bank, i,
+			label,
+			(osr & mask) ? "out" : "in ",
+			(mask & pdsr) ? "hi" : "lo",
+			(mask & pusr) ? "  " : "up");
+		if (ifsr & mask)
+			seq_printf(s, " deglitch");
+		if ((osr & mdsr) & mask)
+			seq_printf(s, " open-drain");
+		if (imr & mask)
+			seq_printf(s, " irq-%d edge-both",
+				gpio_to_irq(chip->base + i));
+		seq_printf(s, "\n");
+	}
+}
+
+#else
+#define pio_bank_show	NULL
+#endif
+
+
+/*--------------------------------------------------------------------------*/
+
 static int __init pio_probe(struct platform_device *pdev)
 {
 	struct pio_device *pio = NULL;
@@ -349,6 +355,18 @@ static int __init pio_probe(struct platf
 	pio = &pio_dev[pdev->id];
 	BUG_ON(!pio->regs);
 
+	pio->chip.label = pio->name;
+	pio->chip.base = pdev->id * 32;
+	pio->chip.ngpio = 32;
+
+	pio->chip.direction_input = direction_input;
+	pio->chip.get = gpio_get;
+	pio->chip.direction_output = direction_output;
+	pio->chip.set = gpio_set;
+	pio->chip.dbg_show = pio_bank_show;
+
+	gpiochip_add(&pio->chip);
+
 	gpio_irq_setup(pio, irq, gpio_irq_base);
 
 	platform_set_drvdata(pdev, pio);
@@ -406,12 +424,6 @@ void __init at32_init_pio(struct platfor
 	pio->pdev = pdev;
 	pio->regs = ioremap(regs->start, regs->end - regs->start + 1);
 
-	/*
-	 * request_gpio() is only valid for pins that have been
-	 * explicitly configured as GPIO and not previously requested
-	 */
-	pio->gpio_mask = ~0UL;
-
 	/* start with irqs disabled and acked */
 	pio_writel(pio, IDR, ~0UL);
 	(void) pio_readl(pio, ISR);
--- at91.orig/arch/avr32/mach-at32ap/pio.h
+++ at91/arch/avr32/mach-at32ap/pio.h
@@ -19,7 +19,7 @@
 #define PIO_OSR                                0x0018
 #define PIO_IFER                               0x0020
 #define PIO_IFDR                               0x0024
-#define PIO_ISFR                               0x0028
+#define PIO_IFSR                               0x0028
 #define PIO_SODR                               0x0030
 #define PIO_CODR                               0x0034
 #define PIO_ODSR                               0x0038
--- at91.orig/include/asm-avr32/arch-at32ap/at32ap7000.h
+++ at91/include/asm-avr32/arch-at32ap/at32ap7000.h
@@ -13,8 +13,6 @@
 #define GPIO_PERIPH_A	0
 #define GPIO_PERIPH_B	1
 
-#define NR_GPIO_CONTROLLERS	4
-
 /*
  * Pin numbers identifying specific GPIO pins on the chip. They can
  * also be converted to IRQ numbers by passing them through
--- at91.orig/include/asm-avr32/arch-at32ap/gpio.h
+++ at91/include/asm-avr32/arch-at32ap/gpio.h
@@ -5,20 +5,36 @@
 #include <asm/irq.h>
 
 
-/* Arch-neutral GPIO API */
-int __must_check gpio_request(unsigned int gpio, const char *label);
-void gpio_free(unsigned int gpio);
-
-int gpio_direction_input(unsigned int gpio);
-int gpio_direction_output(unsigned int gpio, int value);
-int gpio_get_value(unsigned int gpio);
-void gpio_set_value(unsigned int gpio, int value);
+/* Some GPIO chips can manage IRQs; some can't.  The exact numbers can
+ * be changed if needed, but for the moment they're not configurable.
+ */
+#define ARCH_NR_GPIOS	(NR_GPIO_IRQS + 2 * 32)
+
+
+/* Arch-neutral GPIO API, supporting both "native" and external GPIOs. */
+#include <asm-generic/gpio.h>
+
+static inline int gpio_get_value(unsigned int gpio)
+{
+	return __gpio_get_value(gpio);
+}
+
+static inline void gpio_set_value(unsigned int gpio, int value)
+{
+	__gpio_set_value(gpio, value);
+}
+
+static inline int gpio_cansleep(unsigned int gpio)
+{
+	return __gpio_cansleep(gpio);
+}
 
-#include <asm-generic/gpio.h>		/* cansleep wrappers */
 
 static inline int gpio_to_irq(unsigned int gpio)
 {
-	return gpio + GPIO_IRQ_BASE;
+	if (gpio < NR_GPIO_IRQS)
+		return gpio + GPIO_IRQ_BASE;
+	return -EINVAL;
 }
 
 static inline int irq_to_gpio(unsigned int irq)
--- at91.orig/include/asm-avr32/arch-at32ap/irq.h
+++ at91/include/asm-avr32/arch-at32ap/irq.h
@@ -3,11 +3,11 @@
 
 #define EIM_IRQ_BASE	NR_INTERNAL_IRQS
 #define NR_EIM_IRQS	32
-
 #define AT32_EXTINT(n)	(EIM_IRQ_BASE + (n))
 
 #define GPIO_IRQ_BASE	(EIM_IRQ_BASE + NR_EIM_IRQS)
-#define NR_GPIO_IRQS	(5 * 32)
+#define NR_GPIO_CTLR	(5 /*internal*/ + 1 /*external*/)
+#define NR_GPIO_IRQS	(NR_GPIO_CTLR * 32)
 
 #define NR_IRQS		(GPIO_IRQ_BASE + NR_GPIO_IRQS)
 

Re: [patch 2.6.24-rc6-mm 4/9] gpiolib: avr32 at32ap platform support

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Teach AVR32 to use the "GPIO Library" when exposing its GPIOs, so that
signals on external chips (like GPIO expanders) can easily be used.

This mostly reorganizes some existing logic, with two minor changes
in behavior:

 - The PSR registers are used instead of the previous "gpio_mask" values,
   matching AT91 behavior and removing some duplication between that role
   and that of "pinmux_mask".

 - NR_IRQs grew to acommodate a bank of external GPIOs.  Eventually this
   number should probably become a board-specific config option.

There's a debugfs dump of status for the built-in GPIOs, showing which
pins have deglitching, pullups, or open drain drive enabled, as well as
the ID string used when requesting each IRQ.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
---
Incorporates cleanup as suggested by Sam Ravnborg.

 arch/avr32/Kconfig                         |    1 
 arch/avr32/mach-at32ap/pio.c               |  172 +++++++++++++++--------------
 arch/avr32/mach-at32ap/pio.h               |    2 
 include/asm-avr32/arch-at32ap/at32ap7000.h |    2 
 include/asm-avr32/arch-at32ap/gpio.h       |   36 ++++--
 include/asm-avr32/arch-at32ap/irq.h        |    4 
 6 files changed, 122 insertions(+), 95 deletions(-)

--- at91.orig/arch/avr32/Kconfig	2008-01-05 11:59:32.000000000 -0800
+++ at91/arch/avr32/Kconfig	2008-01-05 12:01:11.000000000 -0800
@@ -80,6 +80,7 @@ config PLATFORM_AT32AP
 	select SUBARCH_AVR32B
 	select MMU
 	select PERFORMANCE_COUNTERS
+	select HAVE_GPIO_LIB
 
 choice
 	prompt "AVR32 CPU type"
--- at91.orig/arch/avr32/mach-at32ap/pio.c	2008-01-05 11:59:32.000000000 -0800
+++ at91/arch/avr32/mach-at32ap/pio.c	2008-01-05 12:01:11.000000000 -0800
@@ -24,11 +24,11 @@
 #define MAX_NR_PIO_DEVICES		8
 
 struct pio_device {
+	struct gpio_chip chip;
 	void __iomem *regs;
 	const struct platform_device *pdev;
 	struct clk *clk;
 	u32 pinmux_mask;
-	u32 gpio_mask;
 	char name[8];
 };
 
@@ -64,7 +64,8 @@ void __init at32_select_periph(unsigned 
 		goto fail;
 	}
 
-	if (unlikely(test_and_set_bit(pin_index, &pio->pinmux_mask))) {
+	if (unlikely(test_and_set_bit(pin_index, &pio->pinmux_mask)
+			 || gpiochip_is_requested(&pio->chip, pin_index))) {
 		printk("%s: pin %u is busy\n", pio->name, pin_index);
 		goto fail;
 	}
@@ -79,9 +80,6 @@ void __init at32_select_periph(unsigned 
 	if (!(flags & AT32_GPIOF_PULLUP))
 		pio_writel(pio, PUDR, mask);
 
-	/* gpio_request NOT allowed */
-	set_bit(pin_index, &pio->gpio_mask);
-
 	return;
 
 fail:
@@ -130,9 +128,6 @@ void __init at32_select_gpio(unsigned in
 
 	pio_writel(pio, PER, mask);
 
-	/* gpio_request now allowed */
-	clear_bit(pin_index, &pio->gpio_mask);
-
 	return;
 
 fail:
@@ -166,96 +161,50 @@ fail:
 
 /* GPIO API */
 
-int gpio_request(unsigned int gpio, const char *label)
+static int direction_input(struct gpio_chip *chip, unsigned offset)
 {
-	struct pio_device *pio;
-	unsigned int pin;
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32 mask = 1 << offset;
 
-	pio = gpio_to_pio(gpio);
-	if (!pio)
-		return -ENODEV;
-
-	pin = gpio & 0x1f;
-	if (test_and_set_bit(pin, &pio->gpio_mask))
-		return -EBUSY;
+	if (!(pio_readl(pio, PSR) & mask))
+		return -EINVAL;
 
+	pio_writel(pio, ODR, mask);
 	return 0;
 }
-EXPORT_SYMBOL(gpio_request);
 
-void gpio_free(unsigned int gpio)
+static int gpio_get(struct gpio_chip *chip, unsigned offset)
 {
-	struct pio_device *pio;
-	unsigned int pin;
-
-	pio = gpio_to_pio(gpio);
-	if (!pio) {
-		printk(KERN_ERR
-		       "gpio: attempted to free invalid pin %u\n", gpio);
-		return;
-	}
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
 
-	pin = gpio & 0x1f;
-	if (!test_and_clear_bit(pin, &pio->gpio_mask))
-		printk(KERN_ERR "gpio: freeing free or non-gpio pin %s-%u\n",
-		       pio->name, pin);
+	return (pio_readl(pio, PDSR) >> offset) & 1;
 }
-EXPORT_SYMBOL(gpio_free);
 
-int gpio_direction_input(unsigned int gpio)
-{
-	struct pio_device *pio;
-	unsigned int pin;
-
-	pio = gpio_to_pio(gpio);
-	if (!pio)
-		return -ENODEV;
+static void gpio_set(struct gpio_chip *chip, unsigned offset, int value);
 
-	pin = gpio & 0x1f;
-	pio_writel(pio, ODR, 1 << pin);
-
-	return 0;
-}
-EXPORT_SYMBOL(gpio_direction_input);
-
-int gpio_direction_output(unsigned int gpio, int value)
+static int direction_output(struct gpio_chip *chip, unsigned offset, int value)
 {
-	struct pio_device *pio;
-	unsigned int pin;
-
-	pio = gpio_to_pio(gpio);
-	if (!pio)
-		return -ENODEV;
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32 mask = 1 << offset;
 
-	gpio_set_value(gpio, value);
-
-	pin = gpio & 0x1f;
-	pio_writel(pio, OER, 1 << pin);
+	if (!(pio_readl(pio, PSR) & mask))
+		return -EINVAL;
 
+	gpio_set(chip, offset, value);
+	pio_writel(pio, OER, mask);
 	return 0;
 }
-EXPORT_SYMBOL(gpio_direction_output);
 
-int gpio_get_value(unsigned int gpio)
+static void gpio_set(struct gpio_chip *chip, unsigned offset, int value)
 {
-	struct pio_device *pio = &pio_dev[gpio >> 5];
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32 mask = 1 << offset;
 
-	return (pio_readl(pio, PDSR) >> (gpio & 0x1f)) & 1;
-}
-EXPORT_SYMBOL(gpio_get_value);
-
-void gpio_set_value(unsigned int gpio, int value)
-{
-	struct pio_device *pio = &pio_dev[gpio >> 5];
-	u32 mask;
-
-	mask = 1 << (gpio & 0x1f);
 	if (value)
 		pio_writel(pio, SODR, mask);
 	else
 		pio_writel(pio, CODR, mask);
 }
-EXPORT_SYMBOL(gpio_set_value);
 
 /*--------------------------------------------------------------------------*/
 
@@ -339,6 +288,63 @@ gpio_irq_setup(struct pio_device *pio, i
 
 /*--------------------------------------------------------------------------*/
 
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/seq_file.h>
+
+/*
+ * This shows more info than the generic gpio dump code:
+ * pullups, deglitching, open drain drive.
+ */
+static void pio_bank_show(struct seq_file *s, struct gpio_chip *chip)
+{
+	struct pio_device *pio = container_of(chip, struct pio_device, chip);
+	u32			psr, osr, imr, pdsr, pusr, ifsr, mdsr;
+	unsigned		i;
+	u32			mask;
+	char			bank;
+
+	psr = pio_readl(pio, PSR);
+	osr = pio_readl(pio, OSR);
+	imr = pio_readl(pio, IMR);
+	pdsr = pio_readl(pio, PDSR);
+	pusr = pio_readl(pio, PUSR);
+	ifsr = pio_readl(pio, IFSR);
+	mdsr = pio_readl(pio, MDSR);
+
+	bank = 'A' + pio->pdev->id;
+
+	for (i = 0, mask = 1; i < 32; i++, mask <<= 1) {
+		const char *label;
+
+		label = gpiochip_is_requested(chip, i);
+		if (!label)
+			continue;
+
+		seq_printf(s, " gpio-%-3d P%c%-2d (%-12s) %s %s %s",
+			chip->base + i, bank, i,
+			label,
+			(osr & mask) ? "out" : "in ",
+			(mask & pdsr) ? "hi" : "lo",
+			(mask & pusr) ? "  " : "up");
+		if (ifsr & mask)
+			seq_printf(s, " deglitch");
+		if ((osr & mdsr) & mask)
+			seq_printf(s, " open-drain");
+		if (imr & mask)
+			seq_printf(s, " irq-%d edge-both",
+				gpio_to_irq(chip->base + i));
+		seq_printf(s, "\n");
+	}
+}
+
+#else
+#define pio_bank_show	NULL
+#endif
+
+
+/*--------------------------------------------------------------------------*/
+
 static int __init pio_probe(struct platform_device *pdev)
 {
 	struct pio_device *pio = NULL;
@@ -349,6 +355,18 @@ static int __init pio_probe(struct platf
 	pio = &pio_dev[pdev->id];
 	BUG_ON(!pio->regs);
 
+	pio->chip.label = pio->name;
+	pio->chip.base = pdev->id * 32;
+	pio->chip.ngpio = 32;
+
+	pio->chip.direction_input = direction_input;
+	pio->chip.get = gpio_get;
+	pio->chip.direction_output = direction_output;
+	pio->chip.set = gpio_set;
+	pio->chip.dbg_show = pio_bank_show;
+
+	gpiochip_add(&pio->chip);
+
 	gpio_irq_setup(pio, irq, gpio_irq_base);
 
 	platform_set_drvdata(pdev, pio);
@@ -406,12 +424,6 @@ void __init at32_init_pio(struct platfor
 	pio->pdev = pdev;
 	pio->regs = ioremap(regs->start, regs->end - regs->start + 1);
 
-	/*
-	 * request_gpio() is only valid for pins that have been
-	 * explicitly configured as GPIO and not previously requested
-	 */
-	pio->gpio_mask = ~0UL;
-
 	/* start with irqs disabled and acked */
 	pio_writel(pio, IDR, ~0UL);
 	(void) pio_readl(pio, ISR);
--- at91.orig/arch/avr32/mach-at32ap/pio.h	2008-01-05 11:59:32.000000000 -0800
+++ at91/arch/avr32/mach-at32ap/pio.h	2008-01-05 12:01:11.000000000 -0800
@@ -19,7 +19,7 @@
 #define PIO_OSR                                0x0018
 #define PIO_IFER                               0x0020
 #define PIO_IFDR                               0x0024
-#define PIO_ISFR                               0x0028
+#define PIO_IFSR                               0x0028
 #define PIO_SODR                               0x0030
 #define PIO_CODR                               0x0034
 #define PIO_ODSR                               0x0038
--- at91.orig/include/asm-avr32/arch-at32ap/at32ap7000.h	2008-01-05 11:59:33.000000000 -0800
+++ at91/include/asm-avr32/arch-at32ap/at32ap7000.h	2008-01-05 12:01:11.000000000 -0800
@@ -13,8 +13,6 @@
 #define GPIO_PERIPH_A	0
 #define GPIO_PERIPH_B	1
 
-#define NR_GPIO_CONTROLLERS	4
-
 /*
  * Pin numbers identifying specific GPIO pins on the chip. They can
  * also be converted to IRQ numbers by passing them through
--- at91.orig/include/asm-avr32/arch-at32ap/gpio.h	2008-01-05 11:59:32.000000000 -0800
+++ at91/include/asm-avr32/arch-at32ap/gpio.h	2008-01-05 12:01:11.000000000 -0800
@@ -5,20 +5,36 @@
 #include <asm/irq.h>
 
 
-/* Arch-neutral GPIO API */
-int __must_check gpio_request(unsigned int gpio, const char *label);
-void gpio_free(unsigned int gpio);
-
-int gpio_direction_input(unsigned int gpio);
-int gpio_direction_output(unsigned int gpio, int value);
-int gpio_get_value(unsigned int gpio);
-void gpio_set_value(unsigned int gpio, int value);
+/* Some GPIO chips can manage IRQs; some can't.  The exact numbers can
+ * be changed if needed, but for the moment they're not configurable.
+ */
+#define ARCH_NR_GPIOS	(NR_GPIO_IRQS + 2 * 32)
+
+
+/* Arch-neutral GPIO API, supporting both "native" and external GPIOs. */
+#include <asm-generic/gpio.h>
+
+static inline int gpio_get_value(unsigned int gpio)
+{
+	return __gpio_get_value(gpio);
+}
+
+static inline void gpio_set_value(unsigned int gpio, int value)
+{
+	__gpio_set_value(gpio, value);
+}
+
+static inline int gpio_cansleep(unsigned int gpio)
+{
+	return __gpio_cansleep(gpio);
+}
 
-#include <asm-generic/gpio.h>		/* cansleep wrappers */
 
 static inline int gpio_to_irq(unsigned int gpio)
 {
-	return gpio + GPIO_IRQ_BASE;
+	if (gpio < NR_GPIO_IRQS)
+		return gpio + GPIO_IRQ_BASE;
+	return -EINVAL;
 }
 
 static inline int irq_to_gpio(unsigned int irq)
--- at91.orig/include/asm-avr32/arch-at32ap/irq.h	2008-01-05 11:59:32.000000000 -0800
+++ at91/include/asm-avr32/arch-at32ap/irq.h	2008-01-05 12:01:11.000000000 -0800
@@ -3,11 +3,11 @@
 
 #define EIM_IRQ_BASE	NR_INTERNAL_IRQS
 #define NR_EIM_IRQS	32
-
 #define AT32_EXTINT(n)	(EIM_IRQ_BASE + (n))
 
 #define GPIO_IRQ_BASE	(EIM_IRQ_BASE + NR_EIM_IRQS)
-#define NR_GPIO_IRQS	(5 * 32)
+#define NR_GPIO_CTLR	(5 /*internal*/ + 1 /*external*/)
+#define NR_GPIO_IRQS	(NR_GPIO_CTLR * 32)
 
 #define NR_IRQS		(GPIO_IRQ_BASE + NR_GPIO_IRQS)
 

Re: [patch 2.6.24-rc6-mm 4/9] gpiolib: avr32 at32ap platform support

[Haavard Skinnemoen]

On Sat, 5 Jan 2008 12:10:56 -0800
David Brownell <david-b@pacbell.net> wrote:

> From: David Brownell <dbrownell@users.sourceforge.net>
> 
> Teach AVR32 to use the "GPIO Library" when exposing its GPIOs, so that
> signals on external chips (like GPIO expanders) can easily be used.
> 
> This mostly reorganizes some existing logic, with two minor changes
> in behavior:
> 
>  - The PSR registers are used instead of the previous "gpio_mask"
> values, matching AT91 behavior and removing some duplication between
> that role and that of "pinmux_mask".
> 
>  - NR_IRQs grew to acommodate a bank of external GPIOs.  Eventually
> this number should probably become a board-specific config option.
> 
> There's a debugfs dump of status for the built-in GPIOs, showing which
> pins have deglitching, pullups, or open drain drive enabled, as well
> as the ID string used when requesting each IRQ.
> 
> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>

Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

I'm not going to merge it since the rest of gpiolib isn't in mainline
yet.

Haavard

Re: [patch 2.6.24-rc6-mm 4/9] gpiolib: avr32 at32ap platform support

[David Brownell]

On Saturday 05 January 2008, Haavard Skinnemoen wrote:
> On Sat, 5 Jan 2008 12:10:56 -0800
> David Brownell <david-b@pacbell.net> wrote:
> 
> > From: David Brownell <dbrownell@users.sourceforge.net>
> > 
> > Teach AVR32 to use the "GPIO Library" when exposing its GPIOs, so that
> > signals on external chips (like GPIO expanders) can easily be used.
> > 
> > This mostly reorganizes some existing logic ...
> 
> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

Thanks ... an ack is better than that informal "OK".  ;)


> I'm not going to merge it since the rest of gpiolib isn't in mainline
> yet.

Right.  That's why the PXA support is going through Andrew too.

[patch 2.6.24-rc6-mm 5/9] gpiolib: pxa platform support

[David Brownell]

From: Philipp Zabel <philipp.zabel@gmail.com>

This adds gpiolib support for the PXA architecture:
  - move all GPIO API functions from generic.c into gpio.c
  - convert the gpio_get/set_value macros into inline functions

This makes it easier to hook up GPIOs provided by external chips like
ASICs and CPLDs, as used on various product and developer boards.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 arch/arm/Kconfig                    |    1 
 arch/arm/mach-pxa/Makefile          |    2 
 arch/arm/mach-pxa/generic.c         |   93 ----------------
 arch/arm/mach-pxa/generic.h         |    1 
 arch/arm/mach-pxa/gpio.c            |  197 ++++++++++++++++++++++++++++++++++++
 arch/arm/mach-pxa/irq.c             |    2 
 include/asm-arm/arch-pxa/gpio.h     |   48 +++-----
 include/asm-arm/arch-pxa/pxa-regs.h |   13 ++
 8 files changed, 235 insertions(+), 122 deletions(-)
 create mode 100644 arch/arm/mach-pxa/gpio.c

--- at91.orig/arch/arm/Kconfig
+++ at91/arch/arm/Kconfig
@@ -345,6 +345,7 @@ config ARCH_PXA
 	select GENERIC_GPIO
 	select GENERIC_TIME
 	select GENERIC_CLOCKEVENTS
+	select GPIO_LIB
 	help
 	  Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
 
--- at91.orig/arch/arm/mach-pxa/Makefile
+++ at91/arch/arm/mach-pxa/Makefile
@@ -3,7 +3,7 @@
 #
 
 # Common support (must be linked before board specific support)
-obj-y				+= clock.o generic.o irq.o dma.o time.o
+obj-y				+= clock.o generic.o gpio.o irq.o dma.o time.o
 obj-$(CONFIG_PXA25x)		+= pxa25x.o
 obj-$(CONFIG_PXA27x)		+= pxa27x.o
 obj-$(CONFIG_PXA3xx)		+= pxa3xx.o mfp.o
--- at91.orig/arch/arm/mach-pxa/generic.c
+++ at91/arch/arm/mach-pxa/generic.c
@@ -32,7 +32,6 @@
 #include <asm/mach/map.h>
 
 #include <asm/arch/pxa-regs.h>
-#include <asm/arch/gpio.h>
 #include <asm/arch/udc.h>
 #include <asm/arch/pxafb.h>
 #include <asm/arch/mmc.h>
@@ -73,97 +72,6 @@ unsigned int get_memclk_frequency_10khz(
 EXPORT_SYMBOL(get_memclk_frequency_10khz);
 
 /*
- * Handy function to set GPIO alternate functions
- */
-int pxa_last_gpio;
-
-int pxa_gpio_mode(int gpio_mode)
-{
-	unsigned long flags;
-	int gpio = gpio_mode & GPIO_MD_MASK_NR;
-	int fn = (gpio_mode & GPIO_MD_MASK_FN) >> 8;
-	int gafr;
-
-	if (gpio > pxa_last_gpio)
-		return -EINVAL;
-
-	local_irq_save(flags);
-	if (gpio_mode & GPIO_DFLT_LOW)
-		GPCR(gpio) = GPIO_bit(gpio);
-	else if (gpio_mode & GPIO_DFLT_HIGH)
-		GPSR(gpio) = GPIO_bit(gpio);
-	if (gpio_mode & GPIO_MD_MASK_DIR)
-		GPDR(gpio) |= GPIO_bit(gpio);
-	else
-		GPDR(gpio) &= ~GPIO_bit(gpio);
-	gafr = GAFR(gpio) & ~(0x3 << (((gpio) & 0xf)*2));
-	GAFR(gpio) = gafr |  (fn  << (((gpio) & 0xf)*2));
-	local_irq_restore(flags);
-
-	return 0;
-}
-
-EXPORT_SYMBOL(pxa_gpio_mode);
-
-int gpio_direction_input(unsigned gpio)
-{
-	unsigned long flags;
-	u32 mask;
-
-	if (gpio > pxa_last_gpio)
-		return -EINVAL;
-
-	mask = GPIO_bit(gpio);
-	local_irq_save(flags);
-	GPDR(gpio) &= ~mask;
-	local_irq_restore(flags);
-
-	return 0;
-}
-EXPORT_SYMBOL(gpio_direction_input);
-
-int gpio_direction_output(unsigned gpio, int value)
-{
-	unsigned long flags;
-	u32 mask;
-
-	if (gpio > pxa_last_gpio)
-		return -EINVAL;
-
-	mask = GPIO_bit(gpio);
-	local_irq_save(flags);
-	if (value)
-		GPSR(gpio) = mask;
-	else
-		GPCR(gpio) = mask;
-	GPDR(gpio) |= mask;
-	local_irq_restore(flags);
-
-	return 0;
-}
-EXPORT_SYMBOL(gpio_direction_output);
-
-/*
- * Return GPIO level
- */
-int pxa_gpio_get_value(unsigned gpio)
-{
-	return __gpio_get_value(gpio);
-}
-
-EXPORT_SYMBOL(pxa_gpio_get_value);
-
-/*
- * Set output GPIO level
- */
-void pxa_gpio_set_value(unsigned gpio, int value)
-{
-	__gpio_set_value(gpio, value);
-}
-
-EXPORT_SYMBOL(pxa_gpio_set_value);
-
-/*
  * Routine to safely enable or disable a clock in the CKEN
  */
 void __pxa_set_cken(int clock, int enable)
@@ -178,7 +86,6 @@ void __pxa_set_cken(int clock, int enabl
 
 	local_irq_restore(flags);
 }
-
 EXPORT_SYMBOL(__pxa_set_cken);
 
 /*
--- at91.orig/arch/arm/mach-pxa/generic.h
+++ at91/arch/arm/mach-pxa/generic.h
@@ -16,6 +16,7 @@ extern void __init pxa_init_irq_low(void
 extern void __init pxa_init_irq_high(void);
 extern void __init pxa_init_irq_gpio(int gpio_nr);
 extern void __init pxa_init_irq_set_wake(int (*set_wake)(unsigned int, unsigned int));
+extern void __init pxa_init_gpio(int gpio_nr);
 extern void __init pxa25x_init_irq(void);
 extern void __init pxa27x_init_irq(void);
 extern void __init pxa3xx_init_irq(void);
--- /dev/null
+++ at91/arch/arm/mach-pxa/gpio.c
@@ -0,0 +1,197 @@
+/*
+ *  linux/arch/arm/mach-pxa/gpio.c
+ *
+ *  Generic PXA GPIO handling
+ *
+ *  Author:	Nicolas Pitre
+ *  Created:	Jun 15, 2001
+ *  Copyright:	MontaVista Software Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include <asm/gpio.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/arch/pxa-regs.h>
+
+#include "generic.h"
+
+
+struct pxa_gpio_chip {
+	struct gpio_chip chip;
+	void __iomem     *regbase;
+};
+
+int pxa_last_gpio;
+
+/*
+ * Configure pins for GPIO or other functions
+ */
+int pxa_gpio_mode(int gpio_mode)
+{
+	unsigned long flags;
+	int gpio = gpio_mode & GPIO_MD_MASK_NR;
+	int fn = (gpio_mode & GPIO_MD_MASK_FN) >> 8;
+	int gafr;
+
+	if (gpio > pxa_last_gpio)
+		return -EINVAL;
+
+	local_irq_save(flags);
+	if (gpio_mode & GPIO_DFLT_LOW)
+		GPCR(gpio) = GPIO_bit(gpio);
+	else if (gpio_mode & GPIO_DFLT_HIGH)
+		GPSR(gpio) = GPIO_bit(gpio);
+	if (gpio_mode & GPIO_MD_MASK_DIR)
+		GPDR(gpio) |= GPIO_bit(gpio);
+	else
+		GPDR(gpio) &= ~GPIO_bit(gpio);
+	gafr = GAFR(gpio) & ~(0x3 << (((gpio) & 0xf)*2));
+	GAFR(gpio) = gafr |  (fn  << (((gpio) & 0xf)*2));
+	local_irq_restore(flags);
+
+	return 0;
+}
+EXPORT_SYMBOL(pxa_gpio_mode);
+
+static int pxa_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned long        flags;
+	u32                  mask = 1 << offset;
+	u32                  value;
+	struct pxa_gpio_chip *pxa;
+	void __iomem         *gpdr;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+	gpdr = pxa->regbase + GPDR_OFFSET;
+	local_irq_save(flags);
+	value = __raw_readl(gpdr);
+	value &= ~mask;
+	__raw_writel(value, gpdr);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static int pxa_gpio_direction_output(struct gpio_chip *chip,
+					unsigned offset, int value)
+{
+	unsigned long        flags;
+	u32                  mask = 1 << offset;
+	u32                  tmp;
+	struct pxa_gpio_chip *pxa;
+	void __iomem         *gpdr;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+	__raw_writel(mask,
+			pxa->regbase + (value ? GPSR_OFFSET : GPCR_OFFSET));
+	gpdr = pxa->regbase + GPDR_OFFSET;
+	local_irq_save(flags);
+	tmp = __raw_readl(gpdr);
+	tmp |= mask;
+	__raw_writel(tmp, gpdr);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+/*
+ * Return GPIO level
+ */
+static int pxa_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	u32                  mask = 1 << offset;
+	struct pxa_gpio_chip *pxa;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+	return __raw_readl(pxa->regbase + GPLR_OFFSET) & mask;
+}
+
+/*
+ * Set output GPIO level
+ */
+static void pxa_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	u32                  mask = 1 << offset;
+	struct pxa_gpio_chip *pxa;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+
+	if (value)
+		__raw_writel(mask, pxa->regbase + GPSR_OFFSET);
+	else
+		__raw_writel(mask, pxa->regbase + GPCR_OFFSET);
+}
+
+static struct pxa_gpio_chip pxa_gpio_chip[] = {
+	[0] = {
+		.regbase = GPIO0_BASE,
+		.chip = {
+			.label            = "gpio-0",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 0,
+			.ngpio            = 32,
+		},
+	},
+	[1] = {
+		.regbase = GPIO1_BASE,
+		.chip = {
+			.label            = "gpio-1",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 32,
+			.ngpio            = 32,
+		},
+	},
+	[2] = {
+		.regbase = GPIO2_BASE,
+		.chip = {
+			.label            = "gpio-2",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 64,
+			.ngpio            = 32, /* 21 for PXA25x */
+		},
+	},
+#if defined(CONFIG_PXA27x) || defined(CONFIG_PXA3xx)
+	[3] = {
+		.regbase = GPIO3_BASE,
+		.chip = {
+			.label            = "gpio-3",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 96,
+			.ngpio            = 32,
+		},
+	},
+#endif
+};
+
+void __init pxa_init_gpio(int gpio_nr)
+{
+	int i;
+
+	/* add a GPIO chip for each register bank.
+	 * the last PXA25x register only contains 21 GPIOs
+	 */
+	for (i = 0; i < gpio_nr; i += 32) {
+		if (i+32 > gpio_nr)
+			pxa_gpio_chip[i/32].chip.ngpio = gpio_nr - i;
+		gpiochip_add(&pxa_gpio_chip[i/32].chip);
+	}
+}
--- at91.orig/arch/arm/mach-pxa/irq.c
+++ at91/arch/arm/mach-pxa/irq.c
@@ -310,6 +310,8 @@ void __init pxa_init_irq_gpio(int gpio_n
 	/* Install handler for GPIO>=2 edge detect interrupts */
 	set_irq_chip(IRQ_GPIO_2_x, &pxa_internal_chip_low);
 	set_irq_chained_handler(IRQ_GPIO_2_x, pxa_gpio_demux_handler);
+
+	pxa_init_gpio(gpio_nr);
 }
 
 void __init pxa_init_irq_set_wake(int (*set_wake)(unsigned int, unsigned int))
--- at91.orig/include/asm-arm/arch-pxa/gpio.h
+++ at91/include/asm-arm/arch-pxa/gpio.h
@@ -28,43 +28,35 @@
 #include <asm/irq.h>
 #include <asm/hardware.h>
 
-static inline int gpio_request(unsigned gpio, const char *label)
-{
-	return 0;
-}
+#include <asm-generic/gpio.h>
 
-static inline void gpio_free(unsigned gpio)
-{
-	return;
-}
 
-extern int gpio_direction_input(unsigned gpio);
-extern int gpio_direction_output(unsigned gpio, int value);
+/* NOTE: some PXAs have fewer on-chip GPIOs (like PXA255, with 85).
+ * Those cases currently cause holes in the GPIO number space.
+ */
+#define NR_BUILTIN_GPIO 128
 
-static inline int __gpio_get_value(unsigned gpio)
+static inline int gpio_get_value(unsigned gpio)
 {
-	return GPLR(gpio) & GPIO_bit(gpio);
+	if (__builtin_constant_p(gpio) && (gpio < NR_BUILTIN_GPIO))
+		return GPLR(gpio) & GPIO_bit(gpio);
+	else
+		return __gpio_get_value(gpio);
 }
 
-#define gpio_get_value(gpio)			\
-	(__builtin_constant_p(gpio) ?		\
-	 __gpio_get_value(gpio) :		\
-	 pxa_gpio_get_value(gpio))
-
-static inline void __gpio_set_value(unsigned gpio, int value)
+static inline void gpio_set_value(unsigned gpio, int value)
 {
-	if (value)
-		GPSR(gpio) = GPIO_bit(gpio);
-	else
-		GPCR(gpio) = GPIO_bit(gpio);
+	if (__builtin_constant_p(gpio) && (gpio < NR_BUILTIN_GPIO)) {
+		if (value)
+			GPSR(gpio) = GPIO_bit(gpio);
+		else
+			GPCR(gpio) = GPIO_bit(gpio);
+	} else {
+		__gpio_set_value(gpio, value);
+	}
 }
 
-#define gpio_set_value(gpio,value)		\
-	(__builtin_constant_p(gpio) ?		\
-	 __gpio_set_value(gpio, value) :	\
-	 pxa_gpio_set_value(gpio, value))
-
-#include <asm-generic/gpio.h>			/* cansleep wrappers */
+#define gpio_cansleep __gpio_cansleep
 
 #define gpio_to_irq(gpio)	IRQ_GPIO(gpio)
 #define irq_to_gpio(irq)	IRQ_TO_GPIO(irq)
--- at91.orig/include/asm-arm/arch-pxa/pxa-regs.h
+++ at91/include/asm-arm/arch-pxa/pxa-regs.h
@@ -1131,6 +1131,19 @@
  * General Purpose I/O
  */
 
+#define GPIO0_BASE	((void __iomem *)io_p2v(0x40E00000))
+#define GPIO1_BASE	((void __iomem *)io_p2v(0x40E00004))
+#define GPIO2_BASE	((void __iomem *)io_p2v(0x40E00008))
+#define GPIO3_BASE	((void __iomem *)io_p2v(0x40E00100))
+
+#define GPLR_OFFSET	0x00
+#define GPDR_OFFSET	0x0C
+#define GPSR_OFFSET	0x18
+#define GPCR_OFFSET	0x24
+#define GRER_OFFSET	0x30
+#define GFER_OFFSET	0x3C
+#define GEDR_OFFSET	0x48
+
 #define GPLR0		__REG(0x40E00000)  /* GPIO Pin-Level Register GPIO<31:0> */
 #define GPLR1		__REG(0x40E00004)  /* GPIO Pin-Level Register GPIO<63:32> */
 #define GPLR2		__REG(0x40E00008)  /* GPIO Pin-Level Register GPIO<80:64> */

Re: [patch 2.6.24-rc6-mm 5/9] gpiolib: pxa platform support

[David Brownell]

Subject: [PATCH] gpiolib support for the PXA architecture
From: Philipp Zabel <philipp.zabel@gmail.com>

This adds gpiolib support for the PXA architecture:
  - move all GPIO API functions from generic.c into gpio.c
  - convert the gpio_get/set_value macros into inline functions

This makes it easier to hook up GPIOs provided by external chips like
ASICs and CPLDs.

Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
Incorporates minor cleanup suggested by Sam Ravnborg.

 arch/arm/Kconfig                    |    1 
 arch/arm/mach-pxa/Makefile          |    2 
 arch/arm/mach-pxa/generic.c         |   93 ----------------
 arch/arm/mach-pxa/generic.h         |    1 
 arch/arm/mach-pxa/gpio.c            |  197 ++++++++++++++++++++++++++++++++++++
 arch/arm/mach-pxa/irq.c             |    2 
 include/asm-arm/arch-pxa/gpio.h     |   48 +++-----
 include/asm-arm/arch-pxa/pxa-regs.h |   13 ++
 8 files changed, 235 insertions(+), 122 deletions(-)
 create mode 100644 arch/arm/mach-pxa/gpio.c

--- at91.orig/arch/arm/Kconfig	2008-01-05 12:00:47.000000000 -0800
+++ at91/arch/arm/Kconfig	2008-01-05 12:01:13.000000000 -0800
@@ -345,6 +345,7 @@ config ARCH_PXA
 	select GENERIC_GPIO
 	select GENERIC_TIME
 	select GENERIC_CLOCKEVENTS
+	select HAVE_GPIO_LIB
 	help
 	  Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
 
--- at91.orig/arch/arm/mach-pxa/Makefile	2008-01-05 11:46:02.000000000 -0800
+++ at91/arch/arm/mach-pxa/Makefile	2008-01-05 12:01:13.000000000 -0800
@@ -3,7 +3,7 @@
 #
 
 # Common support (must be linked before board specific support)
-obj-y				+= clock.o generic.o irq.o dma.o time.o
+obj-y				+= clock.o generic.o gpio.o irq.o dma.o time.o
 obj-$(CONFIG_PXA25x)		+= pxa25x.o
 obj-$(CONFIG_PXA27x)		+= pxa27x.o
 obj-$(CONFIG_PXA3xx)		+= pxa3xx.o mfp.o
--- at91.orig/arch/arm/mach-pxa/generic.c	2008-01-05 11:46:02.000000000 -0800
+++ at91/arch/arm/mach-pxa/generic.c	2008-01-05 12:01:13.000000000 -0800
@@ -32,7 +32,6 @@
 #include <asm/mach/map.h>
 
 #include <asm/arch/pxa-regs.h>
-#include <asm/arch/gpio.h>
 #include <asm/arch/udc.h>
 #include <asm/arch/pxafb.h>
 #include <asm/arch/mmc.h>
@@ -73,97 +72,6 @@ unsigned int get_memclk_frequency_10khz(
 EXPORT_SYMBOL(get_memclk_frequency_10khz);
 
 /*
- * Handy function to set GPIO alternate functions
- */
-int pxa_last_gpio;
-
-int pxa_gpio_mode(int gpio_mode)
-{
-	unsigned long flags;
-	int gpio = gpio_mode & GPIO_MD_MASK_NR;
-	int fn = (gpio_mode & GPIO_MD_MASK_FN) >> 8;
-	int gafr;
-
-	if (gpio > pxa_last_gpio)
-		return -EINVAL;
-
-	local_irq_save(flags);
-	if (gpio_mode & GPIO_DFLT_LOW)
-		GPCR(gpio) = GPIO_bit(gpio);
-	else if (gpio_mode & GPIO_DFLT_HIGH)
-		GPSR(gpio) = GPIO_bit(gpio);
-	if (gpio_mode & GPIO_MD_MASK_DIR)
-		GPDR(gpio) |= GPIO_bit(gpio);
-	else
-		GPDR(gpio) &= ~GPIO_bit(gpio);
-	gafr = GAFR(gpio) & ~(0x3 << (((gpio) & 0xf)*2));
-	GAFR(gpio) = gafr |  (fn  << (((gpio) & 0xf)*2));
-	local_irq_restore(flags);
-
-	return 0;
-}
-
-EXPORT_SYMBOL(pxa_gpio_mode);
-
-int gpio_direction_input(unsigned gpio)
-{
-	unsigned long flags;
-	u32 mask;
-
-	if (gpio > pxa_last_gpio)
-		return -EINVAL;
-
-	mask = GPIO_bit(gpio);
-	local_irq_save(flags);
-	GPDR(gpio) &= ~mask;
-	local_irq_restore(flags);
-
-	return 0;
-}
-EXPORT_SYMBOL(gpio_direction_input);
-
-int gpio_direction_output(unsigned gpio, int value)
-{
-	unsigned long flags;
-	u32 mask;
-
-	if (gpio > pxa_last_gpio)
-		return -EINVAL;
-
-	mask = GPIO_bit(gpio);
-	local_irq_save(flags);
-	if (value)
-		GPSR(gpio) = mask;
-	else
-		GPCR(gpio) = mask;
-	GPDR(gpio) |= mask;
-	local_irq_restore(flags);
-
-	return 0;
-}
-EXPORT_SYMBOL(gpio_direction_output);
-
-/*
- * Return GPIO level
- */
-int pxa_gpio_get_value(unsigned gpio)
-{
-	return __gpio_get_value(gpio);
-}
-
-EXPORT_SYMBOL(pxa_gpio_get_value);
-
-/*
- * Set output GPIO level
- */
-void pxa_gpio_set_value(unsigned gpio, int value)
-{
-	__gpio_set_value(gpio, value);
-}
-
-EXPORT_SYMBOL(pxa_gpio_set_value);
-
-/*
  * Routine to safely enable or disable a clock in the CKEN
  */
 void __pxa_set_cken(int clock, int enable)
@@ -178,7 +86,6 @@ void __pxa_set_cken(int clock, int enabl
 
 	local_irq_restore(flags);
 }
-
 EXPORT_SYMBOL(__pxa_set_cken);
 
 /*
--- at91.orig/arch/arm/mach-pxa/generic.h	2008-01-05 11:46:02.000000000 -0800
+++ at91/arch/arm/mach-pxa/generic.h	2008-01-05 12:01:13.000000000 -0800
@@ -16,6 +16,7 @@ extern void __init pxa_init_irq_low(void
 extern void __init pxa_init_irq_high(void);
 extern void __init pxa_init_irq_gpio(int gpio_nr);
 extern void __init pxa_init_irq_set_wake(int (*set_wake)(unsigned int, unsigned int));
+extern void __init pxa_init_gpio(int gpio_nr);
 extern void __init pxa25x_init_irq(void);
 extern void __init pxa27x_init_irq(void);
 extern void __init pxa3xx_init_irq(void);
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/arch/arm/mach-pxa/gpio.c	2008-01-05 12:01:13.000000000 -0800
@@ -0,0 +1,197 @@
+/*
+ *  linux/arch/arm/mach-pxa/gpio.c
+ *
+ *  Generic PXA GPIO handling
+ *
+ *  Author:	Nicolas Pitre
+ *  Created:	Jun 15, 2001
+ *  Copyright:	MontaVista Software Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include <asm/gpio.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/arch/pxa-regs.h>
+
+#include "generic.h"
+
+
+struct pxa_gpio_chip {
+	struct gpio_chip chip;
+	void __iomem     *regbase;
+};
+
+int pxa_last_gpio;
+
+/*
+ * Configure pins for GPIO or other functions
+ */
+int pxa_gpio_mode(int gpio_mode)
+{
+	unsigned long flags;
+	int gpio = gpio_mode & GPIO_MD_MASK_NR;
+	int fn = (gpio_mode & GPIO_MD_MASK_FN) >> 8;
+	int gafr;
+
+	if (gpio > pxa_last_gpio)
+		return -EINVAL;
+
+	local_irq_save(flags);
+	if (gpio_mode & GPIO_DFLT_LOW)
+		GPCR(gpio) = GPIO_bit(gpio);
+	else if (gpio_mode & GPIO_DFLT_HIGH)
+		GPSR(gpio) = GPIO_bit(gpio);
+	if (gpio_mode & GPIO_MD_MASK_DIR)
+		GPDR(gpio) |= GPIO_bit(gpio);
+	else
+		GPDR(gpio) &= ~GPIO_bit(gpio);
+	gafr = GAFR(gpio) & ~(0x3 << (((gpio) & 0xf)*2));
+	GAFR(gpio) = gafr |  (fn  << (((gpio) & 0xf)*2));
+	local_irq_restore(flags);
+
+	return 0;
+}
+EXPORT_SYMBOL(pxa_gpio_mode);
+
+static int pxa_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	unsigned long        flags;
+	u32                  mask = 1 << offset;
+	u32                  value;
+	struct pxa_gpio_chip *pxa;
+	void __iomem         *gpdr;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+	gpdr = pxa->regbase + GPDR_OFFSET;
+	local_irq_save(flags);
+	value = __raw_readl(gpdr);
+	value &= ~mask;
+	__raw_writel(value, gpdr);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static int pxa_gpio_direction_output(struct gpio_chip *chip,
+					unsigned offset, int value)
+{
+	unsigned long        flags;
+	u32                  mask = 1 << offset;
+	u32                  tmp;
+	struct pxa_gpio_chip *pxa;
+	void __iomem         *gpdr;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+	__raw_writel(mask,
+			pxa->regbase + (value ? GPSR_OFFSET : GPCR_OFFSET));
+	gpdr = pxa->regbase + GPDR_OFFSET;
+	local_irq_save(flags);
+	tmp = __raw_readl(gpdr);
+	tmp |= mask;
+	__raw_writel(tmp, gpdr);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+/*
+ * Return GPIO level
+ */
+static int pxa_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	u32                  mask = 1 << offset;
+	struct pxa_gpio_chip *pxa;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+	return __raw_readl(pxa->regbase + GPLR_OFFSET) & mask;
+}
+
+/*
+ * Set output GPIO level
+ */
+static void pxa_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	u32                  mask = 1 << offset;
+	struct pxa_gpio_chip *pxa;
+
+	pxa = container_of(chip, struct pxa_gpio_chip, chip);
+
+	if (value)
+		__raw_writel(mask, pxa->regbase + GPSR_OFFSET);
+	else
+		__raw_writel(mask, pxa->regbase + GPCR_OFFSET);
+}
+
+static struct pxa_gpio_chip pxa_gpio_chip[] = {
+	[0] = {
+		.regbase = GPIO0_BASE,
+		.chip = {
+			.label            = "gpio-0",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 0,
+			.ngpio            = 32,
+		},
+	},
+	[1] = {
+		.regbase = GPIO1_BASE,
+		.chip = {
+			.label            = "gpio-1",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 32,
+			.ngpio            = 32,
+		},
+	},
+	[2] = {
+		.regbase = GPIO2_BASE,
+		.chip = {
+			.label            = "gpio-2",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 64,
+			.ngpio            = 32, /* 21 for PXA25x */
+		},
+	},
+#if defined(CONFIG_PXA27x) || defined(CONFIG_PXA3xx)
+	[3] = {
+		.regbase = GPIO3_BASE,
+		.chip = {
+			.label            = "gpio-3",
+			.direction_input  = pxa_gpio_direction_input,
+			.direction_output = pxa_gpio_direction_output,
+			.get              = pxa_gpio_get,
+			.set              = pxa_gpio_set,
+			.base             = 96,
+			.ngpio            = 32,
+		},
+	},
+#endif
+};
+
+void __init pxa_init_gpio(int gpio_nr)
+{
+	int i;
+
+	/* add a GPIO chip for each register bank.
+	 * the last PXA25x register only contains 21 GPIOs
+	 */
+	for (i = 0; i < gpio_nr; i += 32) {
+		if (i+32 > gpio_nr)
+			pxa_gpio_chip[i/32].chip.ngpio = gpio_nr - i;
+		gpiochip_add(&pxa_gpio_chip[i/32].chip);
+	}
+}
--- at91.orig/arch/arm/mach-pxa/irq.c	2008-01-05 11:46:02.000000000 -0800
+++ at91/arch/arm/mach-pxa/irq.c	2008-01-05 12:01:13.000000000 -0800
@@ -310,6 +310,8 @@ void __init pxa_init_irq_gpio(int gpio_n
 	/* Install handler for GPIO>=2 edge detect interrupts */
 	set_irq_chip(IRQ_GPIO_2_x, &pxa_internal_chip_low);
 	set_irq_chained_handler(IRQ_GPIO_2_x, pxa_gpio_demux_handler);
+
+	pxa_init_gpio(gpio_nr);
 }
 
 void __init pxa_init_irq_set_wake(int (*set_wake)(unsigned int, unsigned int))
--- at91.orig/include/asm-arm/arch-pxa/gpio.h	2008-01-05 11:46:02.000000000 -0800
+++ at91/include/asm-arm/arch-pxa/gpio.h	2008-01-05 12:01:13.000000000 -0800
@@ -28,43 +28,35 @@
 #include <asm/irq.h>
 #include <asm/hardware.h>
 
-static inline int gpio_request(unsigned gpio, const char *label)
-{
-	return 0;
-}
+#include <asm-generic/gpio.h>
 
-static inline void gpio_free(unsigned gpio)
-{
-	return;
-}
 
-extern int gpio_direction_input(unsigned gpio);
-extern int gpio_direction_output(unsigned gpio, int value);
+/* NOTE: some PXAs have fewer on-chip GPIOs (like PXA255, with 85).
+ * Those cases currently cause holes in the GPIO number space.
+ */
+#define NR_BUILTIN_GPIO 128
 
-static inline int __gpio_get_value(unsigned gpio)
+static inline int gpio_get_value(unsigned gpio)
 {
-	return GPLR(gpio) & GPIO_bit(gpio);
+	if (__builtin_constant_p(gpio) && (gpio < NR_BUILTIN_GPIO))
+		return GPLR(gpio) & GPIO_bit(gpio);
+	else
+		return __gpio_get_value(gpio);
 }
 
-#define gpio_get_value(gpio)			\
-	(__builtin_constant_p(gpio) ?		\
-	 __gpio_get_value(gpio) :		\
-	 pxa_gpio_get_value(gpio))
-
-static inline void __gpio_set_value(unsigned gpio, int value)
+static inline void gpio_set_value(unsigned gpio, int value)
 {
-	if (value)
-		GPSR(gpio) = GPIO_bit(gpio);
-	else
-		GPCR(gpio) = GPIO_bit(gpio);
+	if (__builtin_constant_p(gpio) && (gpio < NR_BUILTIN_GPIO)) {
+		if (value)
+			GPSR(gpio) = GPIO_bit(gpio);
+		else
+			GPCR(gpio) = GPIO_bit(gpio);
+	} else {
+		__gpio_set_value(gpio, value);
+	}
 }
 
-#define gpio_set_value(gpio,value)		\
-	(__builtin_constant_p(gpio) ?		\
-	 __gpio_set_value(gpio, value) :	\
-	 pxa_gpio_set_value(gpio, value))
-
-#include <asm-generic/gpio.h>			/* cansleep wrappers */
+#define gpio_cansleep __gpio_cansleep
 
 #define gpio_to_irq(gpio)	IRQ_GPIO(gpio)
 #define irq_to_gpio(irq)	IRQ_TO_GPIO(irq)
--- at91.orig/include/asm-arm/arch-pxa/pxa-regs.h	2008-01-05 11:46:02.000000000 -0800
+++ at91/include/asm-arm/arch-pxa/pxa-regs.h	2008-01-05 12:01:13.000000000 -0800
@@ -1131,6 +1131,19 @@
  * General Purpose I/O
  */
 
+#define GPIO0_BASE	((void __iomem *)io_p2v(0x40E00000))
+#define GPIO1_BASE	((void __iomem *)io_p2v(0x40E00004))
+#define GPIO2_BASE	((void __iomem *)io_p2v(0x40E00008))
+#define GPIO3_BASE	((void __iomem *)io_p2v(0x40E00100))
+
+#define GPLR_OFFSET	0x00
+#define GPDR_OFFSET	0x0C
+#define GPSR_OFFSET	0x18
+#define GPCR_OFFSET	0x24
+#define GRER_OFFSET	0x30
+#define GFER_OFFSET	0x3C
+#define GEDR_OFFSET	0x48
+
 #define GPLR0		__REG(0x40E00000)  /* GPIO Pin-Level Register GPIO<31:0> */
 #define GPLR1		__REG(0x40E00004)  /* GPIO Pin-Level Register GPIO<63:32> */
 #define GPLR2		__REG(0x40E00008)  /* GPIO Pin-Level Register GPIO<80:64> */

[patch 2.6.24-rc6-mm 6/9] gpiolib: pcf857x i2c gpio expander support

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

This is a new-style I2C driver for most common 8 and 16 bit I2C based
"quasi-bidirectional" GPIO expanders:  pcf8574 or pcf8575, and several
compatible models (mostly faster, supporting I2C at up to 1 MHz).

The driver exposes the GPIO signals using the platform-neutral GPIO
programming interface, so they are easily accessed by other kernel code.
The lack of such a flexible kernel API has been a big factor in the
proliferation of board-specific drivers for these chips... stuff that
rarely makes it upstream since it's so ugly.  This driver will let such
boards use standard calls.

Since it's a new-style driver, these devices must be configured as
part of board-specific init.  That eliminates the need for error-prone
manual configuration of module parameters, and makes compatibility with
legacy drivers (pcf8574.c, pc8575.c) for these chips easier (there's
a clear either/or disjunction).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/gpio/Kconfig        |   23 +++
 drivers/gpio/Makefile       |    2 
 drivers/gpio/pcf857x.c      |  330 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c/pcf857x.h |   45 ++++++
 4 files changed, 400 insertions(+)

--- at91.orig/drivers/gpio/Kconfig
+++ at91/drivers/gpio/Kconfig
@@ -27,6 +27,29 @@ config DEBUG_GPIO
 
 comment "I2C GPIO expanders:"
 
+config GPIO_PCF857X
+	tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
+	depends on I2C
+	help
+	  Say yes here to provide access to most "quasi-bidirectional" I2C
+	  GPIO expanders used for additional digital outputs or inputs.
+	  Most of these parts are from NXP, though TI is a second source for
+	  some of them.  Compatible models include:
+
+	  8 bits:   pcf8574, pcf8574a, pca8574, pca8574a,
+	            pca9670, pca9672, pca9674, pca9674a
+
+	  16 bits:  pcf8575, pcf8575c, pca8575,
+	            pca9671, pca9673, pca9675
+
+	  Your board setup code will need to declare the expanders in
+	  use, and assign numbers to the GPIOs they expose.  Those GPIOs
+	  can then be used from drivers and other kernel code, just like
+	  other GPIOs, but only accessible from task contexts.
+
+	  This driver provides an in-kernel interface to those GPIOs using
+	  platform-neutral GPIO calls.
+
 comment "SPI GPIO expanders:"
 
 endmenu
--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -1,5 +1,7 @@
 # gpio support: dedicated expander chips, etc
 
+obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
+
 ifeq ($(CONFIG_DEBUG_GPIO),y)
 EXTRA_CFLAGS += -DDEBUG
 endif
--- /dev/null
+++ at91/drivers/gpio/pcf857x.c
@@ -0,0 +1,330 @@
+/*
+ * pcf857x - driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
+ *
+ * Copyright (C) 2007 David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c/pcf857x.h>
+
+#include <asm/gpio.h>
+
+
+/*
+ * The pcf857x, pca857x, and pca967x chips only expose one read and one
+ * write register.  Writing a "one" bit (to match the reset state) lets
+ * that pin be used as an input; it's not an open-drain model, but acts
+ * a bit like one.  This is described as "quasi-bidirectional"; read the
+ * chip documentation for details.
+ *
+ * Many other I2C GPIO expander chips (like the pca953x models) have
+ * more complex register models and more conventional circuitry using
+ * push/pull drivers.  They often use the same 0x20..0x27 addresses as
+ * pcf857x parts, making the "legacy" I2C driver model problematic.
+ */
+struct pcf857x {
+	struct gpio_chip	chip;
+	struct i2c_client	*client;
+	unsigned		out;		/* software latch */
+};
+
+/*-------------------------------------------------------------------------*/
+
+/* Talk to 8-bit I/O expander */
+
+static int pcf857x_input8(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+
+	gpio->out |= (1 << offset);
+	return i2c_smbus_write_byte(gpio->client, gpio->out);
+}
+
+static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	s32		value;
+
+	value = i2c_smbus_read_byte(gpio->client);
+	return (value < 0) ? 0 : (value & (1 << offset));
+}
+
+static int pcf857x_output8(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	unsigned	bit = 1 << offset;
+
+	if (value)
+		gpio->out |= bit;
+	else
+		gpio->out &= ~bit;
+	return i2c_smbus_write_byte(gpio->client, gpio->out);
+}
+
+static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
+{
+	pcf857x_output8(chip, offset, value);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Talk to 16-bit I/O expander */
+
+static int i2c_write_le16(struct i2c_client *client, u16 word)
+{
+	u8 buf[2] = { word & 0xff, word >> 8, };
+	int status;
+
+	status = i2c_master_send(client, buf, 2);
+	return (status < 0) ? status : 0;
+}
+
+static int i2c_read_le16(struct i2c_client *client)
+{
+	u8 buf[2];
+	int status;
+
+	status = i2c_master_recv(client, buf, 2);
+	if (status < 0)
+		return status;
+	return (buf[1] << 8) | buf[0];
+}
+
+static int pcf857x_input16(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+
+	gpio->out |= (1 << offset);
+	return i2c_write_le16(gpio->client, gpio->out);
+}
+
+static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	int		value;
+
+	value = i2c_read_le16(gpio->client);
+	return (value < 0) ? 0 : (value & (1 << offset));
+}
+
+static int pcf857x_output16(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	unsigned	bit = 1 << offset;
+
+	if (value)
+		gpio->out |= bit;
+	else
+		gpio->out &= ~bit;
+	return i2c_write_le16(gpio->client, gpio->out);
+}
+
+static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
+{
+	pcf857x_output16(chip, offset, value);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int pcf857x_probe(struct i2c_client *client)
+{
+	struct pcf857x_platform_data	*pdata;
+	struct pcf857x			*gpio;
+	int				status;
+
+	pdata = client->dev.platform_data;
+	if (!pdata)
+		return -ENODEV;
+
+	/* Allocate, initialize, and register this gpio_chip. */
+	gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->chip.base = pdata->gpio_base;
+	gpio->chip.can_sleep = 1;
+
+	/* NOTE:  the OnSemi jlc1562b is also largely compatible with
+	 * these parts, notably for output.  It has a low-resolution
+	 * DAC instead of pin change IRQs; and its inputs can be the
+	 * result of comparators.
+	 */
+
+	/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
+	 * 9670, 9672, 9764, and 9764a use quite a variety.
+	 *
+	 * NOTE: we don't distinguish here between *4 and *4a parts.
+	 */
+	if (strcmp(client->name, "pcf8574") == 0
+			|| strcmp(client->name, "pca8574") == 0
+			|| strcmp(client->name, "pca9670") == 0
+			|| strcmp(client->name, "pca9672") == 0
+			|| strcmp(client->name, "pca9674") == 0
+			) {
+		gpio->chip.ngpio = 8;
+		gpio->chip.direction_input = pcf857x_input8;
+		gpio->chip.get = pcf857x_get8;
+		gpio->chip.direction_output = pcf857x_output8;
+		gpio->chip.set = pcf857x_set8;
+
+		if (!i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_BYTE))
+			status = -EIO;
+
+		/* fail if there's no chip present */
+		else
+			status = i2c_smbus_read_byte(client);
+
+	/* '75/'75c addresses are 0x20..0x27, just like the '74;
+	 * the '75c doesn't have a current source pulling high.
+	 * 9671, 9673, and 9765 use quite a variety of addresses.
+	 *
+	 * NOTE: we don't distinguish here between '75 and '75c parts.
+	 */
+	} else if (strcmp(client->name, "pcf8575") == 0
+			|| strcmp(client->name, "pca8575") == 0
+			|| strcmp(client->name, "pca9671") == 0
+			|| strcmp(client->name, "pca9673") == 0
+			|| strcmp(client->name, "pca9675") == 0
+			) {
+		gpio->chip.ngpio = 16;
+		gpio->chip.direction_input = pcf857x_input16;
+		gpio->chip.get = pcf857x_get16;
+		gpio->chip.direction_output = pcf857x_output16;
+		gpio->chip.set = pcf857x_set16;
+
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+			status = -EIO;
+
+		/* fail if there's no chip present */
+		else
+			status = i2c_read_le16(client);
+
+	} else
+		status = -ENODEV;
+
+	if (status < 0)
+		goto fail;
+
+	gpio->chip.label = client->name;
+
+	gpio->client = client;
+	i2c_set_clientdata(client, gpio);
+
+	/* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
+	 * We can't actually know whether a pin is configured (a) as output
+	 * and driving the signal low, or (b) as input and reporting a low
+	 * value ... without knowing the last value written since the chip
+	 * came out of reset (if any).  We can't read the latched output.
+	 *
+	 * In short, the only reliable solution for setting up pin direction
+	 * is to do it explicitly.  The setup() method can do that, but it
+	 * may cause transient glitching since it can't know the last value
+	 * written (some pins may need to be driven low).
+	 *
+	 * Using pdata->n_latch avoids that trouble.  When left initialized
+	 * to zero, our software copy of the "latch" then matches the chip's
+	 * all-ones reset state.  Otherwise it flags pins to be driven low.
+	 */
+	gpio->out = ~pdata->n_latch;
+
+	status = gpiochip_add(&gpio->chip);
+	if (status < 0)
+		goto fail;
+
+	/* NOTE: these chips can issue "some pin-changed" IRQs, which we
+	 * don't yet even try to use.  Among other issues, the relevant
+	 * genirq state isn't available to modular drivers; and most irq
+	 * methods can't be called from sleeping contexts.
+	 */
+
+	dev_info(&client->dev, "gpios %d..%d on a %s%s\n",
+			gpio->chip.base,
+			gpio->chip.base + gpio->chip.ngpio - 1,
+			client->name,
+			client->irq ? " (irq ignored)" : "");
+
+	/* Let platform code set up the GPIOs and their users.
+	 * Now is the first time anyone could use them.
+	 */
+	if (pdata->setup) {
+		status = pdata->setup(client,
+				gpio->chip.base, gpio->chip.ngpio,
+				pdata->context);
+		if (status < 0)
+			dev_warn(&client->dev, "setup --> %d\n", status);
+	}
+
+	return 0;
+
+fail:
+	dev_dbg(&client->dev, "probe error %d for '%s'\n",
+			status, client->name);
+	kfree(gpio);
+	return status;
+}
+
+static int pcf857x_remove(struct i2c_client *client)
+{
+	struct pcf857x_platform_data	*pdata = client->dev.platform_data;
+	struct pcf857x			*gpio = i2c_get_clientdata(client);
+	int				status = 0;
+
+	if (pdata->teardown) {
+		status = pdata->teardown(client,
+				gpio->chip.base, gpio->chip.ngpio,
+				pdata->context);
+		if (status < 0) {
+			dev_err(&client->dev, "%s --> %d\n",
+					"teardown", status);
+			return status;
+		}
+	}
+
+	status = gpiochip_remove(&gpio->chip);
+	if (status == 0)
+		kfree(gpio);
+	else
+		dev_err(&client->dev, "%s --> %d\n", "remove", status);
+	return status;
+}
+
+static struct i2c_driver pcf857x_driver = {
+	.driver = {
+		.name	= "pcf857x",
+		.owner	= THIS_MODULE,
+	},
+	.probe	= pcf857x_probe,
+	.remove	= pcf857x_remove,
+};
+
+static int __init pcf857x_init(void)
+{
+	return i2c_add_driver(&pcf857x_driver);
+}
+module_init(pcf857x_init);
+
+static void __exit pcf857x_exit(void)
+{
+	i2c_del_driver(&pcf857x_driver);
+}
+module_exit(pcf857x_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Brownell");
--- /dev/null
+++ at91/include/linux/i2c/pcf857x.h
@@ -0,0 +1,45 @@
+#ifndef __LINUX_PCF857X_H
+#define __LINUX_PCF857X_H
+
+/**
+ * struct pcf857x_platform_data - data to set up pcf857x driver
+ * @gpio_base: number of the chip's first GPIO
+ * @n_latch: optional bit-inverse of initial register value; if
+ *	you leave this initialized to zero the driver will act
+ *	like the chip was just reset
+ * @setup: optional callback issued once the GPIOs are valid
+ * @teardown: optional callback issued before the GPIOs are invalidated
+ * @context: optional parameter passed to setup() and teardown()
+ *
+ * In addition to the I2C_BOARD_INFO() state appropriate to each chip,
+ * the i2c_board_info used with the pcf875x driver must provide the
+ * chip "type" ("pcf8574", "pcf8574a", "pcf8575", "pcf8575c") and its
+ * platform_data (pointer to one of these structures) with at least
+ * the gpio_base value initialized.
+ *
+ * The @setup callback may be used with the kind of board-specific glue
+ * which hands the (now-valid) GPIOs to other drivers, or which puts
+ * devices in their initial states using these GPIOs.
+ *
+ * These GPIO chips are only "quasi-bidirectional"; read the chip specs
+ * to understand the behavior.  They don't have separate registers to
+ * record which pins are used for input or output, record which output
+ * values are driven, or provide access to input values.  That must be
+ * inferred by reading the chip's value and knowing the last value written
+ * to it.  If you leave n_latch initialized to zero, that last written
+ * value is presumed to be all ones (as if the chip were just reset).
+ */
+struct pcf857x_platform_data {
+	unsigned	gpio_base;
+	unsigned	n_latch;
+
+	int		(*setup)(struct i2c_client *client,
+					int gpio, unsigned ngpio,
+					void *context);
+	int		(*teardown)(struct i2c_client *client,
+					int gpio, unsigned ngpio,
+					void *context);
+	void		*context;
+};
+
+#endif /* __LINUX_PCF857X_H */

Re: [patch 2.6.24-rc6-mm 6/9] gpiolib: pcf857x i2c gpio expander support

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

This is a new-style I2C driver for most common 8 and 16 bit I2C based
"quasi-bidirectional" GPIO expanders:  pcf8574 or pcf8575, and several
compatible models (mostly faster, supporting I2C at up to 1 MHz).

The driver exposes the GPIO signals using the platform-neutral GPIO
programming interface, so they are easily accessed by other kernel code.
The lack of such a flexible kernel API has been a big factor in the
proliferation of board-specific drivers for these chips... stuff that
rarely makes it upstream since it's so ugly.  This driver will let such
boards use standard calls.

Since it's a new-style driver, these devices must be configured as
part of board-specific init.  That eliminates the need for error-prone
manual configuration of module parameters, and makes compatibility with
legacy drivers (pcf8574.c, pc8575.c) for these chips easier (there's
a clear either/or disjunction).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
---
Needed refresh after cleanup as suggested by Sam Ravnborg.

 drivers/gpio/Kconfig        |   23 +++
 drivers/gpio/Makefile       |    1 
 drivers/gpio/pcf857x.c      |  330 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c/pcf857x.h |   45 ++++++
 4 files changed, 399 insertions(+)

--- at91.orig/drivers/gpio/Kconfig	2008-01-05 12:00:47.000000000 -0800
+++ at91/drivers/gpio/Kconfig	2008-01-05 12:01:59.000000000 -0800
@@ -27,6 +27,29 @@ config DEBUG_GPIO
 
 comment "I2C GPIO expanders:"
 
+config GPIO_PCF857X
+	tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
+	depends on I2C
+	help
+	  Say yes here to provide access to most "quasi-bidirectional" I2C
+	  GPIO expanders used for additional digital outputs or inputs.
+	  Most of these parts are from NXP, though TI is a second source for
+	  some of them.  Compatible models include:
+
+	  8 bits:   pcf8574, pcf8574a, pca8574, pca8574a,
+	            pca9670, pca9672, pca9674, pca9674a
+
+	  16 bits:  pcf8575, pcf8575c, pca8575,
+	            pca9671, pca9673, pca9675
+
+	  Your board setup code will need to declare the expanders in
+	  use, and assign numbers to the GPIOs they expose.  Those GPIOs
+	  can then be used from drivers and other kernel code, just like
+	  other GPIOs, but only accessible from task contexts.
+
+	  This driver provides an in-kernel interface to those GPIOs using
+	  platform-neutral GPIO calls.
+
 comment "SPI GPIO expanders:"
 
 endmenu
--- at91.orig/drivers/gpio/Makefile	2008-01-05 12:01:01.000000000 -0800
+++ at91/drivers/gpio/Makefile	2008-01-05 12:02:27.000000000 -0800
@@ -4,3 +4,4 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
 
 obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpiolib.o
 
+obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/drivers/gpio/pcf857x.c	2008-01-05 12:01:59.000000000 -0800
@@ -0,0 +1,330 @@
+/*
+ * pcf857x - driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
+ *
+ * Copyright (C) 2007 David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c/pcf857x.h>
+
+#include <asm/gpio.h>
+
+
+/*
+ * The pcf857x, pca857x, and pca967x chips only expose one read and one
+ * write register.  Writing a "one" bit (to match the reset state) lets
+ * that pin be used as an input; it's not an open-drain model, but acts
+ * a bit like one.  This is described as "quasi-bidirectional"; read the
+ * chip documentation for details.
+ *
+ * Many other I2C GPIO expander chips (like the pca953x models) have
+ * more complex register models and more conventional circuitry using
+ * push/pull drivers.  They often use the same 0x20..0x27 addresses as
+ * pcf857x parts, making the "legacy" I2C driver model problematic.
+ */
+struct pcf857x {
+	struct gpio_chip	chip;
+	struct i2c_client	*client;
+	unsigned		out;		/* software latch */
+};
+
+/*-------------------------------------------------------------------------*/
+
+/* Talk to 8-bit I/O expander */
+
+static int pcf857x_input8(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+
+	gpio->out |= (1 << offset);
+	return i2c_smbus_write_byte(gpio->client, gpio->out);
+}
+
+static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	s32		value;
+
+	value = i2c_smbus_read_byte(gpio->client);
+	return (value < 0) ? 0 : (value & (1 << offset));
+}
+
+static int pcf857x_output8(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	unsigned	bit = 1 << offset;
+
+	if (value)
+		gpio->out |= bit;
+	else
+		gpio->out &= ~bit;
+	return i2c_smbus_write_byte(gpio->client, gpio->out);
+}
+
+static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
+{
+	pcf857x_output8(chip, offset, value);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Talk to 16-bit I/O expander */
+
+static int i2c_write_le16(struct i2c_client *client, u16 word)
+{
+	u8 buf[2] = { word & 0xff, word >> 8, };
+	int status;
+
+	status = i2c_master_send(client, buf, 2);
+	return (status < 0) ? status : 0;
+}
+
+static int i2c_read_le16(struct i2c_client *client)
+{
+	u8 buf[2];
+	int status;
+
+	status = i2c_master_recv(client, buf, 2);
+	if (status < 0)
+		return status;
+	return (buf[1] << 8) | buf[0];
+}
+
+static int pcf857x_input16(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+
+	gpio->out |= (1 << offset);
+	return i2c_write_le16(gpio->client, gpio->out);
+}
+
+static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	int		value;
+
+	value = i2c_read_le16(gpio->client);
+	return (value < 0) ? 0 : (value & (1 << offset));
+}
+
+static int pcf857x_output16(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct pcf857x	*gpio = container_of(chip, struct pcf857x, chip);
+	unsigned	bit = 1 << offset;
+
+	if (value)
+		gpio->out |= bit;
+	else
+		gpio->out &= ~bit;
+	return i2c_write_le16(gpio->client, gpio->out);
+}
+
+static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
+{
+	pcf857x_output16(chip, offset, value);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int pcf857x_probe(struct i2c_client *client)
+{
+	struct pcf857x_platform_data	*pdata;
+	struct pcf857x			*gpio;
+	int				status;
+
+	pdata = client->dev.platform_data;
+	if (!pdata)
+		return -ENODEV;
+
+	/* Allocate, initialize, and register this gpio_chip. */
+	gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->chip.base = pdata->gpio_base;
+	gpio->chip.can_sleep = 1;
+
+	/* NOTE:  the OnSemi jlc1562b is also largely compatible with
+	 * these parts, notably for output.  It has a low-resolution
+	 * DAC instead of pin change IRQs; and its inputs can be the
+	 * result of comparators.
+	 */
+
+	/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
+	 * 9670, 9672, 9764, and 9764a use quite a variety.
+	 *
+	 * NOTE: we don't distinguish here between *4 and *4a parts.
+	 */
+	if (strcmp(client->name, "pcf8574") == 0
+			|| strcmp(client->name, "pca8574") == 0
+			|| strcmp(client->name, "pca9670") == 0
+			|| strcmp(client->name, "pca9672") == 0
+			|| strcmp(client->name, "pca9674") == 0
+			) {
+		gpio->chip.ngpio = 8;
+		gpio->chip.direction_input = pcf857x_input8;
+		gpio->chip.get = pcf857x_get8;
+		gpio->chip.direction_output = pcf857x_output8;
+		gpio->chip.set = pcf857x_set8;
+
+		if (!i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_BYTE))
+			status = -EIO;
+
+		/* fail if there's no chip present */
+		else
+			status = i2c_smbus_read_byte(client);
+
+	/* '75/'75c addresses are 0x20..0x27, just like the '74;
+	 * the '75c doesn't have a current source pulling high.
+	 * 9671, 9673, and 9765 use quite a variety of addresses.
+	 *
+	 * NOTE: we don't distinguish here between '75 and '75c parts.
+	 */
+	} else if (strcmp(client->name, "pcf8575") == 0
+			|| strcmp(client->name, "pca8575") == 0
+			|| strcmp(client->name, "pca9671") == 0
+			|| strcmp(client->name, "pca9673") == 0
+			|| strcmp(client->name, "pca9675") == 0
+			) {
+		gpio->chip.ngpio = 16;
+		gpio->chip.direction_input = pcf857x_input16;
+		gpio->chip.get = pcf857x_get16;
+		gpio->chip.direction_output = pcf857x_output16;
+		gpio->chip.set = pcf857x_set16;
+
+		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+			status = -EIO;
+
+		/* fail if there's no chip present */
+		else
+			status = i2c_read_le16(client);
+
+	} else
+		status = -ENODEV;
+
+	if (status < 0)
+		goto fail;
+
+	gpio->chip.label = client->name;
+
+	gpio->client = client;
+	i2c_set_clientdata(client, gpio);
+
+	/* NOTE:  these chips have strange "quasi-bidirectional" I/O pins.
+	 * We can't actually know whether a pin is configured (a) as output
+	 * and driving the signal low, or (b) as input and reporting a low
+	 * value ... without knowing the last value written since the chip
+	 * came out of reset (if any).  We can't read the latched output.
+	 *
+	 * In short, the only reliable solution for setting up pin direction
+	 * is to do it explicitly.  The setup() method can do that, but it
+	 * may cause transient glitching since it can't know the last value
+	 * written (some pins may need to be driven low).
+	 *
+	 * Using pdata->n_latch avoids that trouble.  When left initialized
+	 * to zero, our software copy of the "latch" then matches the chip's
+	 * all-ones reset state.  Otherwise it flags pins to be driven low.
+	 */
+	gpio->out = ~pdata->n_latch;
+
+	status = gpiochip_add(&gpio->chip);
+	if (status < 0)
+		goto fail;
+
+	/* NOTE: these chips can issue "some pin-changed" IRQs, which we
+	 * don't yet even try to use.  Among other issues, the relevant
+	 * genirq state isn't available to modular drivers; and most irq
+	 * methods can't be called from sleeping contexts.
+	 */
+
+	dev_info(&client->dev, "gpios %d..%d on a %s%s\n",
+			gpio->chip.base,
+			gpio->chip.base + gpio->chip.ngpio - 1,
+			client->name,
+			client->irq ? " (irq ignored)" : "");
+
+	/* Let platform code set up the GPIOs and their users.
+	 * Now is the first time anyone could use them.
+	 */
+	if (pdata->setup) {
+		status = pdata->setup(client,
+				gpio->chip.base, gpio->chip.ngpio,
+				pdata->context);
+		if (status < 0)
+			dev_warn(&client->dev, "setup --> %d\n", status);
+	}
+
+	return 0;
+
+fail:
+	dev_dbg(&client->dev, "probe error %d for '%s'\n",
+			status, client->name);
+	kfree(gpio);
+	return status;
+}
+
+static int pcf857x_remove(struct i2c_client *client)
+{
+	struct pcf857x_platform_data	*pdata = client->dev.platform_data;
+	struct pcf857x			*gpio = i2c_get_clientdata(client);
+	int				status = 0;
+
+	if (pdata->teardown) {
+		status = pdata->teardown(client,
+				gpio->chip.base, gpio->chip.ngpio,
+				pdata->context);
+		if (status < 0) {
+			dev_err(&client->dev, "%s --> %d\n",
+					"teardown", status);
+			return status;
+		}
+	}
+
+	status = gpiochip_remove(&gpio->chip);
+	if (status == 0)
+		kfree(gpio);
+	else
+		dev_err(&client->dev, "%s --> %d\n", "remove", status);
+	return status;
+}
+
+static struct i2c_driver pcf857x_driver = {
+	.driver = {
+		.name	= "pcf857x",
+		.owner	= THIS_MODULE,
+	},
+	.probe	= pcf857x_probe,
+	.remove	= pcf857x_remove,
+};
+
+static int __init pcf857x_init(void)
+{
+	return i2c_add_driver(&pcf857x_driver);
+}
+module_init(pcf857x_init);
+
+static void __exit pcf857x_exit(void)
+{
+	i2c_del_driver(&pcf857x_driver);
+}
+module_exit(pcf857x_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Brownell");
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/include/linux/i2c/pcf857x.h	2008-01-05 12:01:59.000000000 -0800
@@ -0,0 +1,45 @@
+#ifndef __LINUX_PCF857X_H
+#define __LINUX_PCF857X_H
+
+/**
+ * struct pcf857x_platform_data - data to set up pcf857x driver
+ * @gpio_base: number of the chip's first GPIO
+ * @n_latch: optional bit-inverse of initial register value; if
+ *	you leave this initialized to zero the driver will act
+ *	like the chip was just reset
+ * @setup: optional callback issued once the GPIOs are valid
+ * @teardown: optional callback issued before the GPIOs are invalidated
+ * @context: optional parameter passed to setup() and teardown()
+ *
+ * In addition to the I2C_BOARD_INFO() state appropriate to each chip,
+ * the i2c_board_info used with the pcf875x driver must provide the
+ * chip "type" ("pcf8574", "pcf8574a", "pcf8575", "pcf8575c") and its
+ * platform_data (pointer to one of these structures) with at least
+ * the gpio_base value initialized.
+ *
+ * The @setup callback may be used with the kind of board-specific glue
+ * which hands the (now-valid) GPIOs to other drivers, or which puts
+ * devices in their initial states using these GPIOs.
+ *
+ * These GPIO chips are only "quasi-bidirectional"; read the chip specs
+ * to understand the behavior.  They don't have separate registers to
+ * record which pins are used for input or output, record which output
+ * values are driven, or provide access to input values.  That must be
+ * inferred by reading the chip's value and knowing the last value written
+ * to it.  If you leave n_latch initialized to zero, that last written
+ * value is presumed to be all ones (as if the chip were just reset).
+ */
+struct pcf857x_platform_data {
+	unsigned	gpio_base;
+	unsigned	n_latch;
+
+	int		(*setup)(struct i2c_client *client,
+					int gpio, unsigned ngpio,
+					void *context);
+	int		(*teardown)(struct i2c_client *client,
+					int gpio, unsigned ngpio,
+					void *context);
+	void		*context;
+};
+
+#endif /* __LINUX_PCF857X_H */

[patch 2.6.24-rc6-mm 7/9] gpiolib: mcp23s08 spi gpio expander support

[David Brownell]

From: David Brownell <dbrownell@users.sourceforge.net>

Basic driver for 8-bit SPI based MCP23S08 GPIO expander, without support for
IRQs or the shared chipselect mechanism.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/gpio/Kconfig         |    7 
 drivers/gpio/Makefile        |    1 
 drivers/gpio/mcp23s08.c      |  357 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/spi/mcp23s08.h |   24 ++
 4 files changed, 389 insertions(+)

--- at91.orig/drivers/gpio/Kconfig
+++ at91/drivers/gpio/Kconfig
@@ -52,4 +52,11 @@ config GPIO_PCF857X
 
 comment "SPI GPIO expanders:"
 
+config GPIO_MCP23S08
+	tristate "Microchip MCP23S08 I/O expander"
+	depends on SPI_MASTER
+	help
+	  SPI driver for Microchip MCP23S08 I/O expander.  This provides
+	  a GPIO interface supporting inputs and outputs.
+
 endmenu
--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -1,5 +1,6 @@
 # gpio support: dedicated expander chips, etc
 
+obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 
 ifeq ($(CONFIG_DEBUG_GPIO),y)
--- /dev/null
+++ at91/drivers/gpio/mcp23s08.c
@@ -0,0 +1,357 @@
+/*
+ * mcp23s08.c - SPI gpio expander driver
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/workqueue.h>
+#include <linux/mutex.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/mcp23s08.h>
+
+#include <asm/gpio.h>
+
+
+/* Registers are all 8 bits wide.
+ *
+ * The mcp23s17 has twice as many bits, and can be configured to work
+ * with either 16 bit registers or with two adjacent 8 bit banks.
+ *
+ * Also, there are I2C versions of both chips.
+ */
+#define MCP_IODIR	0x00		/* init/reset:  all ones */
+#define MCP_IPOL	0x01
+#define MCP_GPINTEN	0x02
+#define MCP_DEFVAL	0x03
+#define MCP_INTCON	0x04
+#define MCP_IOCON	0x05
+#	define IOCON_SEQOP	(1 << 5)
+#	define IOCON_HAEN	(1 << 3)
+#	define IOCON_ODR	(1 << 2)
+#	define IOCON_INTPOL	(1 << 1)
+#define MCP_GPPU	0x06
+#define MCP_INTF	0x07
+#define MCP_INTCAP	0x08
+#define MCP_GPIO	0x09
+#define MCP_OLAT	0x0a
+
+struct mcp23s08 {
+	struct spi_device	*spi;
+	u8			addr;
+
+	/* lock protects the cached values */
+	struct mutex		lock;
+	u8			cache[11];
+
+	struct gpio_chip	chip;
+
+	struct work_struct	work;
+};
+
+static int mcp23s08_read(struct mcp23s08 *mcp, unsigned reg)
+{
+	u8	tx[2], rx[1];
+	int	status;
+
+	tx[0] = mcp->addr | 0x01;
+	tx[1] = reg;
+	status = spi_write_then_read(mcp->spi, tx, sizeof tx, rx, sizeof rx);
+	return (status < 0) ? status : rx[0];
+}
+
+static int mcp23s08_write(struct mcp23s08 *mcp, unsigned reg, u8 val)
+{
+	u8	tx[3];
+
+	tx[0] = mcp->addr;
+	tx[1] = reg;
+	tx[2] = val;
+	return spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
+}
+
+static int
+mcp23s08_read_regs(struct mcp23s08 *mcp, unsigned reg, u8 *vals, unsigned n)
+{
+	u8	tx[2];
+
+	if ((n + reg) > sizeof mcp->cache)
+		return -EINVAL;
+	tx[0] = mcp->addr | 0x01;
+	tx[1] = reg;
+	return spi_write_then_read(mcp->spi, tx, sizeof tx, vals, n);
+}
+
+/*----------------------------------------------------------------------*/
+
+static int mcp23s08_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
+	int status;
+
+	mutex_lock(&mcp->lock);
+	mcp->cache[MCP_IODIR] |= (1 << offset);
+	status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
+	mutex_unlock(&mcp->lock);
+	return status;
+}
+
+static int mcp23s08_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
+	int status;
+
+	mutex_lock(&mcp->lock);
+
+	/* REVISIT reading this clears any IRQ ... */
+	status = mcp23s08_read(mcp, MCP_GPIO);
+	if (status < 0)
+		status = 0;
+	else {
+		mcp->cache[MCP_GPIO] = status;
+		status = !!(status & (1 << offset));
+	}
+	mutex_unlock(&mcp->lock);
+	return status;
+}
+
+static int __mcp23s08_set(struct mcp23s08 *mcp, unsigned mask, int value)
+{
+	u8 olat = mcp->cache[MCP_OLAT];
+
+	if (value)
+		olat |= mask;
+	else
+		olat &= ~mask;
+	mcp->cache[MCP_OLAT] = olat;
+	return mcp23s08_write(mcp, MCP_OLAT, olat);
+}
+
+static void mcp23s08_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
+	u8 mask = 1 << offset;
+
+	mutex_lock(&mcp->lock);
+	__mcp23s08_set(mcp, mask, value);
+	mutex_unlock(&mcp->lock);
+}
+
+static int
+mcp23s08_direction_output(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct mcp23s08	*mcp = container_of(chip, struct mcp23s08, chip);
+	u8 mask = 1 << offset;
+	int status;
+
+	mutex_lock(&mcp->lock);
+	status = __mcp23s08_set(mcp, mask, value);
+	if (status == 0) {
+		mcp->cache[MCP_IODIR] &= ~mask;
+		status = mcp23s08_write(mcp, MCP_IODIR, mcp->cache[MCP_IODIR]);
+	}
+	mutex_unlock(&mcp->lock);
+	return status;
+}
+
+/*----------------------------------------------------------------------*/
+
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/seq_file.h>
+
+/*
+ * This shows more info than the generic gpio dump code:
+ * pullups, deglitching, open drain drive.
+ */
+static void mcp23s08_dbg_show(struct seq_file *s, struct gpio_chip *chip)
+{
+	struct mcp23s08	*mcp;
+	char		bank;
+	unsigned	t;
+	unsigned	mask;
+
+	mcp = container_of(chip, struct mcp23s08, chip);
+
+	/* NOTE: we only handle one bank for now ... */
+	bank = '0' + ((mcp->addr >> 1) & 0x3);
+
+	mutex_lock(&mcp->lock);
+	t = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
+	if (t < 0) {
+		seq_printf(s, " I/O ERROR %d\n", t);
+		goto done;
+	}
+
+	for (t = 0, mask = 1; t < 8; t++, mask <<= 1) {
+		const char	*label;
+
+		label = gpiochip_is_requested(chip, t);
+		if (!label)
+			continue;
+
+		seq_printf(s, " gpio-%-3d P%c.%d (%-12s) %s %s %s",
+			chip->base + t, bank, t, label,
+			(mcp->cache[MCP_IODIR] & mask) ? "in " : "out",
+			(mcp->cache[MCP_GPIO] & mask) ? "hi" : "lo",
+			(mcp->cache[MCP_GPPU] & mask) ? "  " : "up");
+		/* NOTE:  ignoring the irq-related registers */
+		seq_printf(s, "\n");
+	}
+done:
+	mutex_unlock(&mcp->lock);
+}
+
+#else
+#define mcp23s08_dbg_show	NULL
+#endif
+
+/*----------------------------------------------------------------------*/
+
+static int mcp23s08_probe(struct spi_device *spi)
+{
+	struct mcp23s08			*mcp;
+	struct mcp23s08_platform_data	*pdata;
+	int				status;
+	int				do_update = 0;
+
+	pdata = spi->dev.platform_data;
+	if (!pdata || pdata->slave > 3 || !pdata->base)
+		return -ENODEV;
+
+	mcp = kzalloc(sizeof *mcp, GFP_KERNEL);
+	if (!mcp)
+		return -ENOMEM;
+
+	mutex_init(&mcp->lock);
+
+	mcp->spi = spi;
+	mcp->addr = 0x40 | (pdata->slave << 1);
+
+	mcp->chip.label = "mcp23s08",
+
+	mcp->chip.direction_input = mcp23s08_direction_input;
+	mcp->chip.get = mcp23s08_get;
+	mcp->chip.direction_output = mcp23s08_direction_output;
+	mcp->chip.set = mcp23s08_set;
+	mcp->chip.dbg_show = mcp23s08_dbg_show;
+
+	mcp->chip.base = pdata->base;
+	mcp->chip.ngpio = 8;
+	mcp->chip.can_sleep = 1;
+
+	spi_set_drvdata(spi, mcp);
+
+	/* verify MCP_IOCON.SEQOP = 0, so sequential reads work */
+	status = mcp23s08_read(mcp, MCP_IOCON);
+	if (status < 0)
+		goto fail;
+	if (status & IOCON_SEQOP) {
+		status &= ~IOCON_SEQOP;
+		status = mcp23s08_write(mcp, MCP_IOCON, (u8) status);
+		if (status < 0)
+			goto fail;
+	}
+
+	/* configure ~100K pullups */
+	status = mcp23s08_write(mcp, MCP_GPPU, pdata->pullups);
+	if (status < 0)
+		goto fail;
+
+	status = mcp23s08_read_regs(mcp, 0, mcp->cache, sizeof mcp->cache);
+	if (status < 0)
+		goto fail;
+
+	/* disable inverter on input */
+	if (mcp->cache[MCP_IPOL] != 0) {
+		mcp->cache[MCP_IPOL] = 0;
+		do_update = 1;
+	}
+
+	/* disable irqs */
+	if (mcp->cache[MCP_GPINTEN] != 0) {
+		mcp->cache[MCP_GPINTEN] = 0;
+		do_update = 1;
+	}
+
+	if (do_update) {
+		u8 tx[4];
+
+		tx[0] = mcp->addr;
+		tx[1] = MCP_IPOL;
+		memcpy(&tx[2], &mcp->cache[MCP_IPOL], sizeof(tx) - 2);
+		status = spi_write_then_read(mcp->spi, tx, sizeof tx, NULL, 0);
+
+		/* FIXME check status... */
+	}
+
+	status = gpiochip_add(&mcp->chip);
+
+	/* NOTE:  these chips have a relatively sane IRQ framework, with
+	 * per-signal masking and level/edge triggering.  It's not yet
+	 * handled here...
+	 */
+
+	if (pdata->setup) {
+		status = pdata->setup(spi, mcp->chip.base,
+				mcp->chip.ngpio, pdata->context);
+		if (status < 0)
+			dev_dbg(&spi->dev, "setup --> %d\n", status);
+	}
+
+	return 0;
+
+fail:
+	kfree(mcp);
+	return status;
+}
+
+static int mcp23s08_remove(struct spi_device *spi)
+{
+	struct mcp23s08			*mcp = spi_get_drvdata(spi);
+	struct mcp23s08_platform_data	*pdata = spi->dev.platform_data;
+	int				status = 0;
+
+	if (pdata->teardown) {
+		status = pdata->teardown(spi,
+				mcp->chip.base, mcp->chip.ngpio,
+				pdata->context);
+		if (status < 0) {
+			dev_err(&spi->dev, "%s --> %d\n", "teardown", status);
+			return status;
+		}
+	}
+
+	status = gpiochip_remove(&mcp->chip);
+	if (status == 0)
+		kfree(mcp);
+	else
+		dev_err(&spi->dev, "%s --> %d\n", "remove", status);
+	return status;
+}
+
+static struct spi_driver mcp23s08_driver = {
+	.probe		= mcp23s08_probe,
+	.remove		= mcp23s08_remove,
+	.driver = {
+		.name	= "mcp23s08",
+		.owner	= THIS_MODULE,
+	},
+};
+
+/*----------------------------------------------------------------------*/
+
+static int __init mcp23s08_init(void)
+{
+	return spi_register_driver(&mcp23s08_driver);
+}
+module_init(mcp23s08_init);
+
+static void __exit mcp23s08_exit(void)
+{
+	spi_unregister_driver(&mcp23s08_driver);
+}
+module_exit(mcp23s08_exit);
+
+MODULE_LICENSE("GPL");
+
--- /dev/null
+++ at91/include/linux/spi/mcp23s08.h
@@ -0,0 +1,24 @@
+
+/* FIXME driver should be able to handle all four slaves that
+ * can be hooked up to each chipselect, as well as IRQs...
+ */
+
+struct mcp23s08_platform_data {
+	/* four slaves can share one SPI chipselect */
+	u8		slave;
+
+	/* number assigned to the first GPIO */
+	unsigned	base;
+
+	/* pins with pullups */
+	u8		pullups;
+
+	void		*context;	/* param to setup/teardown */
+
+	int		(*setup)(struct spi_device *spi,
+					int gpio, unsigned ngpio,
+					void *context);
+	int		(*teardown)(struct spi_device *spi,
+					int gpio, unsigned ngpio,
+					void *context);
+};

[patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support

[David Brownell]

From: eric miao <eric.miao@marvell.com>

This adds a new-style I2C driver with basic support for the sixteen
bit PCA9539 GPIO expanders.  These chips have multiple registers,
push-pull output drivers, and (not supported by this patch) pin
change interrupts.

Board-specific code must provide "pca9539_platform_data" with each
chip's "i2c_board_info".  That provides the GPIO numbers to be used
by that chip, and callbacks for board-specific setup/teardown logic.

Derived from drivers/i2c/chips/pca9539.c (which has no current known
users).  This is faster and simpler; it uses 16-bit register access,
and caches the OUTPUT and DIRECTION registers for fast access.

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/gpio/Kconfig        |   10 +
 drivers/gpio/Makefile       |    1 
 drivers/gpio/pca9539.c      |  264 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c/pca9539.h |   18 +++
 4 files changed, 293 insertions(+)

--- at91.orig/drivers/gpio/Kconfig
+++ at91/drivers/gpio/Kconfig
@@ -27,6 +27,16 @@ config DEBUG_GPIO
 
 comment "I2C GPIO expanders:"
 
+config GPIO_PCA9539
+	tristate "PCA9539 16-bit I/O port"
+	depends on I2C
+	help
+	  Say yes here to support the PCA9539 16-bit I/O port. These
+	  parts are made by NXP and TI.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called pca9539.
+
 config GPIO_PCF857X
 	tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
 	depends on I2C
--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -1,6 +1,7 @@
 # gpio support: dedicated expander chips, etc
 
 obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
+obj-$(CONFIG_GPIO_PCA9539)	+= pca9539.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 
 ifeq ($(CONFIG_DEBUG_GPIO),y)
--- /dev/null
+++ at91/drivers/gpio/pca9539.c
@@ -0,0 +1,264 @@
+/*
+ *  pca9539.c - 16-bit I/O port with interrupt and reset
+ *
+ *  Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+ *  Copyright (C) 2007 Marvell International Ltd.
+ *
+ *  Derived from drivers/i2c/chips/pca9539.c
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/i2c/pca9539.h>
+
+#include <asm/gpio.h>
+
+
+#define NR_PCA9539_GPIOS	16
+
+#define PCA9539_INPUT		0
+#define PCA9539_OUTPUT		2
+#define PCA9539_INVERT		4
+#define PCA9539_DIRECTION	6
+
+struct pca9539_chip {
+	unsigned gpio_start;
+	uint16_t reg_output;
+	uint16_t reg_direction;
+
+	struct i2c_client *client;
+	struct gpio_chip gpio_chip;
+};
+
+/* NOTE:  we can't currently rely on fault codes to come from SMBus
+ * calls, so we map all errors to EIO here and return zero otherwise.
+ */
+static int pca9539_write_reg(struct pca9539_chip *chip, int reg, uint16_t val)
+{
+	if (i2c_smbus_write_word_data(chip->client, reg, val) < 0)
+		return -EIO;
+	else
+		return 0;
+}
+
+static int pca9539_read_reg(struct pca9539_chip *chip, int reg, uint16_t *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(chip->client, reg);
+	if (ret < 0) {
+		dev_err(&chip->client->dev, "failed reading register\n");
+		return -EIO;
+	}
+
+	*val = (uint16_t)ret;
+	return 0;
+}
+
+static int pca9539_gpio_direction_input(struct gpio_chip *gc, unsigned off)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	reg_val = chip->reg_direction | (1u << off);
+	ret = pca9539_write_reg(chip, PCA9539_DIRECTION, reg_val);
+	if (ret)
+		return ret;
+
+	chip->reg_direction = reg_val;
+	return 0;
+}
+
+static int pca9539_gpio_direction_output(struct gpio_chip *gc,
+		unsigned off, int val)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	/* set output level */
+	if (val)
+		reg_val = chip->reg_output | (1u << off);
+	else
+		reg_val = chip->reg_output & ~(1u << off);
+
+	ret = pca9539_write_reg(chip, PCA9539_OUTPUT, reg_val);
+	if (ret)
+		return ret;
+
+	chip->reg_output = reg_val;
+
+	/* then direction */
+	reg_val = chip->reg_direction & ~(1u << off);
+	ret = pca9539_write_reg(chip, PCA9539_DIRECTION, reg_val);
+	if (ret)
+		return ret;
+
+	chip->reg_direction = reg_val;
+	return 0;
+}
+
+static int pca9539_gpio_get_value(struct gpio_chip *gc, unsigned off)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	ret = pca9539_read_reg(chip, PCA9539_INPUT, &reg_val);
+	if (ret < 0) {
+		/* NOTE:  diagnostic already omitted; that's the
+		 * best we can do here.
+		 */
+		return 0;
+	}
+
+	return (reg_val & (1u << off)) ? 1 : 0;
+}
+
+static void pca9539_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	if (val)
+		reg_val = chip->reg_output | (1u << off);
+	else
+		reg_val = chip->reg_output & ~(1u << off);
+
+	ret = pca9539_write_reg(chip, PCA9539_OUTPUT, reg_val);
+	if (ret)
+		return;
+
+	chip->reg_output = reg_val;
+}
+
+static int pca9539_init_gpio(struct pca9539_chip *chip)
+{
+	struct gpio_chip *gc;
+
+	gc = &chip->gpio_chip;
+
+	gc->direction_input  = pca9539_gpio_direction_input;
+	gc->direction_output = pca9539_gpio_direction_output;
+	gc->get = pca9539_gpio_get_value;
+	gc->set = pca9539_gpio_set_value;
+
+	gc->base = chip->gpio_start;
+	gc->ngpio = NR_PCA9539_GPIOS;
+	gc->label = "pca9539";
+
+	return gpiochip_add(gc);
+}
+
+static int __devinit pca9539_probe(struct i2c_client *client)
+{
+	struct pca9539_platform_data *pdata;
+	struct pca9539_chip *chip;
+	int ret;
+
+	pdata = client->dev.platform_data;
+	if (pdata == NULL)
+		return -ENODEV;
+
+	chip = kzalloc(sizeof(struct pca9539_chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+
+	chip->client = client;
+
+	chip->gpio_start = pdata->gpio_base;
+
+	/* initialize cached registers from their original values */
+	ret = pca9539_read_reg(chip, PCA9539_OUTPUT, &chip->reg_output);
+	if (ret)
+		goto out_failed;
+
+	ret = pca9539_read_reg(chip, PCA9539_DIRECTION, &chip->reg_direction);
+	if (ret)
+		goto out_failed;
+
+	/* set platform specific polarity inversion */
+	ret = pca9539_write_reg(chip, PCA9539_INVERT, pdata->invert);
+	if (ret)
+		goto out_failed;
+
+	ret = pca9539_init_gpio(chip);
+	if (ret)
+		goto out_failed;
+
+	if (pdata->setup) {
+		ret = pdata->setup(client, chip->gpio_chip.base,
+				chip->gpio_chip.ngpio, pdata->context);
+		if (ret < 0)
+			dev_dbg(&client->dev, "setup failed, %d\n", ret);
+	}
+
+	i2c_set_clientdata(client, chip);
+	return 0;
+
+out_failed:
+	kfree(chip);
+	return ret;
+}
+
+static int pca9539_remove(struct i2c_client *client)
+{
+	struct pca9539_platform_data *pdata = client->dev.platform_data;
+	struct pca9539_chip *chip = i2c_get_clientdata(client);
+	int ret = 0;
+
+	if (pdata->teardown) {
+		ret = pdata->teardown(client, chip->gpio_chip.base,
+				chip->gpio_chip.ngpio, pdata->context);
+		if (ret < 0)
+			dev_dbg(&client->dev, "teardown failed, %d\n", ret);
+	}
+
+	ret = gpiochip_remove(&chip->gpio_chip);
+	if (ret) {
+		dev_err(&client->dev, "failed remove gpio_chip\n");
+		return ret;
+	}
+
+	kfree(chip);
+	return 0;
+}
+
+static struct i2c_driver pca9539_driver = {
+	.driver = {
+		.name	= "pca9539",
+	},
+	.probe		= pca9539_probe,
+	.remove		= pca9539_remove,
+};
+
+static int __init pca9539_init(void)
+{
+	return i2c_add_driver(&pca9539_driver);
+}
+module_init(pca9539_init);
+
+static void __exit pca9539_exit(void)
+{
+	i2c_del_driver(&pca9539_driver);
+}
+module_exit(pca9539_exit);
+
+MODULE_AUTHOR("eric miao <eric.miao@marvell.com>");
+MODULE_DESCRIPTION("GPIO expander driver for PCA9539");
+MODULE_LICENSE("GPL");
--- /dev/null
+++ at91/include/linux/i2c/pca9539.h
@@ -0,0 +1,18 @@
+/* platform data for the PCA9539 16-bit I/O expander driver */
+
+struct pca9539_platform_data {
+	/* number of the first GPIO */
+	unsigned	gpio_base;
+
+	/* initial polarity inversion setting */
+	uint16_t	invert;
+
+	void		*context;	/* param to setup/teardown */
+
+	int		(*setup)(struct i2c_client *client,
+				unsigned gpio, unsigned ngpio,
+				void *context);
+	int		(*teardown)(struct i2c_client *client,
+				unsigned gpio, unsigned ngpio,
+				void *context);
+};

Re: [patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support

[Jean Delvare]

Hi David, hi Eric,

Le 29/12/2007, "David Brownell" <david-b@pacbell.net> a écrit:
>From: eric miao <eric.miao@marvell.com>
>
>This adds a new-style I2C driver with basic support for the sixteen
>bit PCA9539 GPIO expanders.  These chips have multiple registers,
>push-pull output drivers, and (not supported by this patch) pin
>change interrupts.
>
>Board-specific code must provide "pca9539_platform_data" with each
>chip's "i2c_board_info".  That provides the GPIO numbers to be used
>by that chip, and callbacks for board-specific setup/teardown logic.
>
>Derived from drivers/i2c/chips/pca9539.c (which has no current known
>users).  This is faster and simpler; it uses 16-bit register access,
>and caches the OUTPUT and DIRECTION registers for fast access.
>
>Signed-off-by: eric miao <eric.miao@marvell.com>
>Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
>---
> drivers/gpio/Kconfig        |   10 +
> drivers/gpio/Makefile       |    1
> drivers/gpio/pca9539.c      |  264 ++++++++++++++++++++++++++
> include/linux/i2c/pca9539.h |   18 +++
> 4 files changed, 293 insertions(+)

Random comments:

>+static int pca9539_gpio_get_value(struct gpio_chip *gc, unsigned off)
>+{
>+	struct pca9539_chip *chip;
>+	uint16_t reg_val;
>+	int ret;
>+
>+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
>+
>+	ret = pca9539_read_reg(chip, PCA9539_INPUT, &reg_val);
>+	if (ret < 0) {
>+		/* NOTE:  diagnostic already omitted; that's the
>+		 * best we can do here.
>+		 */
>+		return 0;
>+	}

I guess that you really mean "emitted" here, not "omitted"?

More importantly, I don't agree that it's the best we can do here.
Maybe it was already discussed before and there's a good reason to not
report errors from "get" functions at the gpio-core level, but I
can't see it. Whether a read error should be considered as "0" or
"1" (or neither) should be a decision left to the user of the GPIO
chip, rather than to each GPIO driver.

>+
>+	return (reg_val & (1u << off)) ? 1 : 0;
>+}

>+static int __devinit pca9539_probe(struct i2c_client *client)
>+{
>+ (...)
>+	if (pdata->setup) {
>+		ret = pdata->setup(client, chip->gpio_chip.base,
>+				chip->gpio_chip.ngpio, pdata->context);
>+		if (ret < 0)
>+			dev_dbg(&client->dev, "setup failed, %d\n", ret);

Should be at least dev_warn() and maybe even dev_err().

>+	}
>+ (...)
>+}
>+
>+static int pca9539_remove(struct i2c_client *client)
>+{
>+ (...)
>+	if (pdata->teardown) {
>+		ret = pdata->teardown(client, chip->gpio_chip.base,
>+				chip->gpio_chip.ngpio, pdata->context);
>+		if (ret < 0)
>+			dev_dbg(&client->dev, "teardown failed, %d\n", ret);

Same thing here.

>+	}
>+
>+	ret = gpiochip_remove(&chip->gpio_chip);
>+	if (ret) {
>+		dev_err(&client->dev, "failed remove gpio_chip\n");

This error message could certainly be reworded to sound better. Also, for
consistency you should include the value of "ret" in the message.

>+		return ret;
>+	}
>+
>+	kfree(chip);
>+	return 0;
>+}

--
Jean Delvare

Re: [patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support

[David Brownell]

Le 02 Janvier 2008, Jean Delvare a écrit:
> 
> Hi David, hi Eric,
> 
> Le 29/12/2007, "David Brownell" <david-b@pacbell.net> a écrit:
> >From: eric miao <eric.miao@marvell.com>
> >
> >This adds a new-style I2C driver with basic support for the sixteen
> >bit PCA9539 GPIO expanders.
> >
> >			... 
> 
> Random comments:
> 
> >+static int pca9539_gpio_get_value(struct gpio_chip *gc, unsigned off)
> >+{
> >+		...
> >+
> >+	ret = pca9539_read_reg(chip, PCA9539_INPUT, &reg_val);
> >+	if (ret < 0) {
> >+		/* NOTE:  diagnostic already omitted; that's the
> >+		 * best we can do here.
> >+		 */
> >+		return 0;
> >+	}
> 
> I guess that you really mean "emitted" here, not "omitted"?

Yeah, typo.


> More importantly, I don't agree that it's the best we can do here.
> Maybe it was already discussed before and there's a good reason to not
> report errors from "get" functions at the gpio-core level,

Yes there is.  It's by explicit request.  Expecting drivers to cope
with per-bit errors is at best unrealistic.  This was decided well
over a year ago ... nobody wants to see bit-banging code that spends
more time trying to figure out how to recover from "can't happen"
errors than getting real work done.  (None of the SOC-specific GPIO
interfaces being replaced by this generic one returned errors either.)

That said, with things like I2C there actually *could* be errors;
which are impossible with valid parameters to SOC-level GPIOs.
That might argue for gpio_{get,set}_value_cansleep() calls being
able to return fault codes that would be nonsense on the more
widely used gpio_{get,set}_value() alls.

But such a change would be for a different set of patches.  This
set does not change *any* driver programming interface.  At all.


> >+static int __devinit pca9539_probe(struct i2c_client *client)
> >+{
> >+ (...)
> >+	if (pdata->setup) {
> >+		ret = pdata->setup(client, chip->gpio_chip.base,
> >+				chip->gpio_chip.ngpio, pdata->context);
> >+		if (ret < 0)
> >+			dev_dbg(&client->dev, "setup failed, %d\n", ret);
> 
> Should be at least dev_warn() and maybe even dev_err().

It's not treated as an error (i.e. abort the probe); warning
is right.

Hmm, I thought both this issue and the previous one had been
fixed already ... oh, it was the pcf857x driver that fixed that.
Never mind.  ;)


> >+	}
> >+ (...)
> >+}
> >+
> >+static int pca9539_remove(struct i2c_client *client)
> >+{
> >+ (...)
> >+	if (pdata->teardown) {
> >+		ret = pdata->teardown(client, chip->gpio_chip.base,
> >+				chip->gpio_chip.ngpio, pdata->context);
> >+		if (ret < 0)
> >+			dev_dbg(&client->dev, "teardown failed, %d\n", ret);
> 
> Same thing here.

That was supposed to be dev_err() then "return ret" !


> >+	}
> >+
> >+	ret = gpiochip_remove(&chip->gpio_chip);
> >+	if (ret) {
> >+		dev_err(&client->dev, "failed remove gpio_chip\n");
> 
> This error message could certainly be reworded to sound better. Also, for
> consistency you should include the value of "ret" in the message.

Right.  So, pretty much like the appended.  (Which I'll merge into
refreshed version of this patch.)


--- a/drivers/gpio/pca9539.c
+++ b/drivers/gpio/pca9539.c
@@ -118,7 +118,7 @@ static int pca9539_gpio_get_value(struct
 
 	ret = pca9539_read_reg(chip, PCA9539_INPUT, &reg_val);
 	if (ret < 0) {
-		/* NOTE:  diagnostic already omitted; that's the
+		/* NOTE:  diagnostic already emitted; that's the
 		 * best we can do here.
 		 */
 		return 0;
@@ -205,7 +205,7 @@ static int __devinit pca9539_probe(struc
 		ret = pdata->setup(client, chip->gpio_chip.base,
 				chip->gpio_chip.ngpio, pdata->context);
 		if (ret < 0)
-			dev_dbg(&client->dev, "setup failed, %d\n", ret);
+			dev_warn(&client->dev, "setup failed, %d\n", ret);
 	}
 
 	i2c_set_clientdata(client, chip);
@@ -225,13 +225,17 @@ static int pca9539_remove(struct i2c_cli
 	if (pdata->teardown) {
 		ret = pdata->teardown(client, chip->gpio_chip.base,
 				chip->gpio_chip.ngpio, pdata->context);
-		if (ret < 0)
-			dev_dbg(&client->dev, "teardown failed, %d\n", ret);
+		if (ret < 0) {
+			dev_err(&client->dev, "%s failed, %d\n",
+					"teardown", ret);
+			return ret;
+		}
 	}
 
 	ret = gpiochip_remove(&chip->gpio_chip);
 	if (ret) {
-		dev_err(&client->dev, "failed remove gpio_chip\n");
+		dev_err(&client->dev, "%s failed, %d\n",
+				"gpiochip_remove()", ret);
 		return ret;
 	}
 

Re: [patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support

[David Brownell]

From: eric miao <eric.miao@marvell.com>
Subject: [PATCH] gpiolib: support PCA9539 GPIO expander

This adds a new-style I2C driver with basic support for the sixteen
bit PCA9539 GPIO expanders.  These chips have multiple registers,
push-pull output drivers, and (not supported in this patch) pin
change interrupts.

Board-specific code must provide "pca9539_platform_data" with each
chip's "i2c_board_info".  That provides the GPIO numbers to be used
by that chip, and callbacks for board-specific setup/teardown logic.

Derived from drivers/i2c/chips/pca9539.c (which has no current known
users).  This is faster and simpler; it uses 16-bit register access,
and cache the OUTPUT and DIRECTION registers for fast access

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
Incorporates cleanups noted by Jean Delvare.

 drivers/gpio/Kconfig        |   10 +
 drivers/gpio/Makefile       |    1 
 drivers/gpio/pca9539.c      |  271 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c/pca9539.h |   18 ++
 4 files changed, 300 insertions(+)

--- at91.orig/drivers/gpio/Kconfig	2008-01-05 11:27:12.000000000 -0800
+++ at91/drivers/gpio/Kconfig	2008-01-05 11:27:12.000000000 -0800
@@ -27,6 +27,16 @@ config DEBUG_GPIO
 
 comment "I2C GPIO expanders:"
 
+config GPIO_PCA9539
+	tristate "PCA9539 16-bit I/O port"
+	depends on I2C
+	help
+	  Say yes here to support the PCA9539 16-bit I/O port. These
+	  parts are made by NXP and TI.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called pca9539.
+
 config GPIO_PCF857X
 	tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
 	depends on I2C
--- at91.orig/drivers/gpio/Makefile	2008-01-05 11:27:12.000000000 -0800
+++ at91/drivers/gpio/Makefile	2008-01-05 11:27:12.000000000 -0800
@@ -1,6 +1,7 @@
 # gpio support: dedicated expander chips, etc
 
 obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
+obj-$(CONFIG_GPIO_PCA9539)	+= pca9539.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 
 ifeq ($(CONFIG_DEBUG_GPIO),y)
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/drivers/gpio/pca9539.c	2008-01-05 11:32:06.000000000 -0800
@@ -0,0 +1,271 @@
+/*
+ *  pca9539.c - 16-bit I/O port with interrupt and reset
+ *
+ *  Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+ *  Copyright (C) 2007 Marvell International Ltd.
+ *
+ *  Derived from drivers/i2c/chips/pca9539.c
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/i2c/pca9539.h>
+
+#include <asm/gpio.h>
+
+
+#define NR_PCA9539_GPIOS	16
+
+#define PCA9539_INPUT		0
+#define PCA9539_OUTPUT		2
+#define PCA9539_INVERT		4
+#define PCA9539_DIRECTION	6
+
+struct pca9539_chip {
+	unsigned gpio_start;
+	uint16_t reg_output;
+	uint16_t reg_direction;
+
+	struct i2c_client *client;
+	struct gpio_chip gpio_chip;
+};
+
+/* NOTE:  we can't currently rely on fault codes to come from SMBus
+ * calls, so we map all errors to EIO here and return zero otherwise.
+ */
+static int pca9539_write_reg(struct pca9539_chip *chip, int reg, uint16_t val)
+{
+	if (i2c_smbus_write_word_data(chip->client, reg, val) < 0)
+		return -EIO;
+	else
+		return 0;
+}
+
+static int pca9539_read_reg(struct pca9539_chip *chip, int reg, uint16_t *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(chip->client, reg);
+	if (ret < 0) {
+		dev_err(&chip->client->dev, "failed reading register\n");
+		return -EIO;
+	}
+
+	*val = (uint16_t)ret;
+	return 0;
+}
+
+static int pca9539_gpio_direction_input(struct gpio_chip *gc, unsigned off)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	reg_val = chip->reg_direction | (1u << off);
+	ret = pca9539_write_reg(chip, PCA9539_DIRECTION, reg_val);
+	if (ret)
+		return ret;
+
+	chip->reg_direction = reg_val;
+	return 0;
+}
+
+static int pca9539_gpio_direction_output(struct gpio_chip *gc,
+		unsigned off, int val)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	/* set output level */
+	if (val)
+		reg_val = chip->reg_output | (1u << off);
+	else
+		reg_val = chip->reg_output & ~(1u << off);
+
+	ret = pca9539_write_reg(chip, PCA9539_OUTPUT, reg_val);
+	if (ret)
+		return ret;
+
+	chip->reg_output = reg_val;
+
+	/* then direction */
+	reg_val = chip->reg_direction & ~(1u << off);
+	ret = pca9539_write_reg(chip, PCA9539_DIRECTION, reg_val);
+	if (ret)
+		return ret;
+
+	chip->reg_direction = reg_val;
+	return 0;
+}
+
+static int pca9539_gpio_get_value(struct gpio_chip *gc, unsigned off)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	ret = pca9539_read_reg(chip, PCA9539_INPUT, &reg_val);
+	if (ret < 0) {
+		/* NOTE:  diagnostic already emitted; that's all we should
+		 * do unless gpio_*_value_cansleep() calls become different
+		 * from their nonsleeping siblings (and report faults).
+		 */
+		return 0;
+	}
+
+	return (reg_val & (1u << off)) ? 1 : 0;
+}
+
+static void pca9539_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
+{
+	struct pca9539_chip *chip;
+	uint16_t reg_val;
+	int ret;
+
+	chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+	if (val)
+		reg_val = chip->reg_output | (1u << off);
+	else
+		reg_val = chip->reg_output & ~(1u << off);
+
+	ret = pca9539_write_reg(chip, PCA9539_OUTPUT, reg_val);
+	if (ret)
+		return;
+
+	chip->reg_output = reg_val;
+}
+
+static int pca9539_init_gpio(struct pca9539_chip *chip)
+{
+	struct gpio_chip *gc;
+
+	gc = &chip->gpio_chip;
+
+	gc->direction_input  = pca9539_gpio_direction_input;
+	gc->direction_output = pca9539_gpio_direction_output;
+	gc->get = pca9539_gpio_get_value;
+	gc->set = pca9539_gpio_set_value;
+
+	gc->base = chip->gpio_start;
+	gc->ngpio = NR_PCA9539_GPIOS;
+	gc->label = "pca9539";
+
+	return gpiochip_add(gc);
+}
+
+static int __devinit pca9539_probe(struct i2c_client *client)
+{
+	struct pca9539_platform_data *pdata;
+	struct pca9539_chip *chip;
+	int ret;
+
+	pdata = client->dev.platform_data;
+	if (pdata == NULL)
+		return -ENODEV;
+
+	chip = kzalloc(sizeof(struct pca9539_chip), GFP_KERNEL);
+	if (chip == NULL)
+		return -ENOMEM;
+
+	chip->client = client;
+
+	chip->gpio_start = pdata->gpio_base;
+
+	/* initialize cached registers from their original values.
+	 * we can't share this chip with another i2c master.
+	 */
+	ret = pca9539_read_reg(chip, PCA9539_OUTPUT, &chip->reg_output);
+	if (ret)
+		goto out_failed;
+
+	ret = pca9539_read_reg(chip, PCA9539_DIRECTION, &chip->reg_direction);
+	if (ret)
+		goto out_failed;
+
+	/* set platform specific polarity inversion */
+	ret = pca9539_write_reg(chip, PCA9539_INVERT, pdata->invert);
+	if (ret)
+		goto out_failed;
+
+	ret = pca9539_init_gpio(chip);
+	if (ret)
+		goto out_failed;
+
+	if (pdata->setup) {
+		ret = pdata->setup(client, chip->gpio_chip.base,
+				chip->gpio_chip.ngpio, pdata->context);
+		if (ret < 0)
+			dev_warn(&client->dev, "setup failed, %d\n", ret);
+	}
+
+	i2c_set_clientdata(client, chip);
+	return 0;
+
+out_failed:
+	kfree(chip);
+	return ret;
+}
+
+static int pca9539_remove(struct i2c_client *client)
+{
+	struct pca9539_platform_data *pdata = client->dev.platform_data;
+	struct pca9539_chip *chip = i2c_get_clientdata(client);
+	int ret = 0;
+
+	if (pdata->teardown) {
+		ret = pdata->teardown(client, chip->gpio_chip.base,
+				chip->gpio_chip.ngpio, pdata->context);
+		if (ret < 0) {
+			dev_err(&client->dev, "%s failed, %d\n",
+					"teardown", ret);
+			return ret;
+		}
+	}
+
+	ret = gpiochip_remove(&chip->gpio_chip);
+	if (ret) {
+		dev_err(&client->dev, "%s failed, %d\n",
+				"gpiochip_remove()", ret);
+		return ret;
+	}
+
+	kfree(chip);
+	return 0;
+}
+
+static struct i2c_driver pca9539_driver = {
+	.driver = {
+		.name	= "pca9539",
+	},
+	.probe		= pca9539_probe,
+	.remove		= pca9539_remove,
+};
+
+static int __init pca9539_init(void)
+{
+	return i2c_add_driver(&pca9539_driver);
+}
+module_init(pca9539_init);
+
+static void __exit pca9539_exit(void)
+{
+	i2c_del_driver(&pca9539_driver);
+}
+module_exit(pca9539_exit);
+
+MODULE_AUTHOR("eric miao <eric.miao@marvell.com>");
+MODULE_DESCRIPTION("GPIO expander driver for PCA9539");
+MODULE_LICENSE("GPL");
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ at91/include/linux/i2c/pca9539.h	2008-01-05 11:27:12.000000000 -0800
@@ -0,0 +1,18 @@
+/* platform data for the PCA9539 16-bit I/O expander driver */
+
+struct pca9539_platform_data {
+	/* number of the first GPIO */
+	unsigned	gpio_base;
+
+	/* initial polarity inversion setting */
+	uint16_t	invert;
+
+	void		*context;	/* param to setup/teardown */
+
+	int		(*setup)(struct i2c_client *client,
+				unsigned gpio, unsigned ngpio,
+				void *context);
+	int		(*teardown)(struct i2c_client *client,
+				unsigned gpio, unsigned ngpio,
+				void *context);
+};

Re: [patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support

[Jean Delvare]

On Sat, 5 Jan 2008 11:40:55 -0800, David Brownell wrote:
> From: eric miao <eric.miao@marvell.com>
> Subject: [PATCH] gpiolib: support PCA9539 GPIO expander
> 
> This adds a new-style I2C driver with basic support for the sixteen
> bit PCA9539 GPIO expanders.  These chips have multiple registers,
> push-pull output drivers, and (not supported in this patch) pin
> change interrupts.
> 
> Board-specific code must provide "pca9539_platform_data" with each
> chip's "i2c_board_info".  That provides the GPIO numbers to be used
> by that chip, and callbacks for board-specific setup/teardown logic.
> 
> Derived from drivers/i2c/chips/pca9539.c (which has no current known
> users).  This is faster and simpler; it uses 16-bit register access,
> and cache the OUTPUT and DIRECTION registers for fast access
> 
> Signed-off-by: eric miao <eric.miao@marvell.com>
> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> ---
> Incorporates cleanups noted by Jean Delvare.
> 
>  drivers/gpio/Kconfig        |   10 +
>  drivers/gpio/Makefile       |    1 
>  drivers/gpio/pca9539.c      |  271 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c/pca9539.h |   18 ++
>  4 files changed, 300 insertions(+)

Acked-by: Jean Delvare <khali@linux-fr.org>

-- 
Jean Delvare

[patch 2.6.24-rc6-mm 9/9] gpiolib: deprecate obsolete pca9539 driver

[David Brownell]

From: eric miao <eric.miao@marvell.com>

Use drivers/gpio/pca9539.c instead.

Signed-off-by: eric miao <eric.miao@marvell.com>
Acked-by: Ben Gardner <bgardner@wabtec.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 Documentation/i2c/chips/pca9539 |    3 +++
 drivers/i2c/chips/Kconfig       |    7 +++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

--- at91.orig/Documentation/i2c/chips/pca9539
+++ at91/Documentation/i2c/chips/pca9539
@@ -1,6 +1,9 @@
 Kernel driver pca9539
 =====================
 
+NOTE: this driver is deprecated and will be dropped soon, use
+drivers/gpio/pca9539.c instead.
+
 Supported chips:
   * Philips PCA9539
     Prefix: 'pca9539'
--- at91.orig/drivers/i2c/chips/Kconfig
+++ at91/drivers/i2c/chips/Kconfig
@@ -92,8 +92,8 @@ config SENSORS_PCF8574
 	  hardware.  If unsure, say N.
 
 config SENSORS_PCA9539
-	tristate "Philips PCA9539 16-bit I/O port"
-	depends on EXPERIMENTAL
+	tristate "Philips PCA9539 16-bit I/O port (DEPRECATED)"
+	depends on EXPERIMENTAL && GPIO_PCA9539 = "n"
 	help
 	  If you say yes here you get support for the Philips PCA9539
 	  16-bit I/O port.
@@ -101,6 +101,9 @@ config SENSORS_PCA9539
 	  This driver can also be built as a module.  If so, the module
 	  will be called pca9539.
 
+	  This driver is deprecated and will be dropped soon. Use
+	  drivers/gpio/pca9539.c instead.
+
 config SENSORS_PCF8591
 	tristate "Philips PCF8591"
 	depends on EXPERIMENTAL