[PATCH v1 0/1] gpio: mmio: add get_set inverted direction io support

[PATCH v1 0/1] gpio: mmio: add get_set inverted direction io support

[Tomer Maimon]

When bgpio direction register use dirin and setting  
BGPIOF_READ_OUTPUT_REG_SET flag, the get_set I/O functions reading 
the inverted set register of each direction, it means:

when direction=in the get_set function read set register.
when direction=out the get_set function read dat register.

but is should be inverted.

conversion about it with Linus Walleij:
https://www.spinics.net/lists/devicetree/msg241973.html

to solve it, adding get_set_inv_dir and get_set_multiple_inv_dir
I/O functions to call the data register when the direction is input and
set register when the direction is output.
the functions will linked to the I/O get functions if the user set
BGPIOF_INVERTED_REG_DIR flag in the bgpio initialization.

Tomer Maimon (1):
  gpio: mmio: add inverted direction get_set io support

 drivers/gpio/gpio-mmio.c    | 48 ++++++++++++++++++++++++++++++++++++++++++---
 include/linux/gpio/driver.h |  1 +
 2 files changed, 46 insertions(+), 3 deletions(-)

-- 
2.14.1

[PATCH v1 1/1] gpio: mmio: add inverted direction get_set io support

[Tomer Maimon]

Add get_set_inv_dir and get_set_multiple_inv_dir I/O functions
to call the data register when the dirction is input and
set register when the direction is output.
the functions will linked to the I/O get functions if the user set
BGPIOF_INVERTED_REG_DIR flag in the bgpio initialization.

Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
---
 drivers/gpio/gpio-mmio.c    | 48 ++++++++++++++++++++++++++++++++++++++++++---
 include/linux/gpio/driver.h |  1 +
 2 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c
index 7b14d6280e44..46f664459853 100644
--- a/drivers/gpio/gpio-mmio.c
+++ b/drivers/gpio/gpio-mmio.c
@@ -168,6 +168,40 @@ static int bgpio_get_set_multiple(struct gpio_chip *gc, unsigned long *mask,
 	return 0;
 }
 
+/* get set function when the direction is inverted */
+static int bgpio_get_set_inv_dir(struct gpio_chip *gc, unsigned int gpio)
+{
+	unsigned long pinmask = bgpio_line2mask(gc, gpio);
+
+	if (gc->bgpio_dir & pinmask)
+		return !!(gc->read_reg(gc->reg_dat) & pinmask);
+	else
+		return !!(gc->read_reg(gc->reg_set) & pinmask);
+}
+
+/* get set multiple function when the direction is inverted */
+static int bgpio_get_set_multiple_inv_dir(struct gpio_chip *gc,
+					  unsigned long *mask,
+					  unsigned long *bits)
+{
+	unsigned long get_mask = 0;
+	unsigned long set_mask = 0;
+
+	/* Make sure we first clear any bits that are zero when we read the register */
+	*bits &= ~*mask;
+
+	/* Exploit the fact that we know which directions are set */
+	set_mask = *mask & ~gc->bgpio_dir;
+	get_mask = *mask & gc->bgpio_dir;
+
+	if (set_mask)
+		*bits |= gc->read_reg(gc->reg_set) & set_mask;
+	if (get_mask)
+		*bits |= gc->read_reg(gc->reg_dat) & get_mask;
+
+	return 0;
+}
+
 static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
 {
 	return !!(gc->read_reg(gc->reg_dat) & bgpio_line2mask(gc, gpio));
@@ -525,9 +559,17 @@ static int bgpio_setup_io(struct gpio_chip *gc,
 
 	if (!(flags & BGPIOF_UNREADABLE_REG_SET) &&
 	    (flags & BGPIOF_READ_OUTPUT_REG_SET)) {
-		gc->get = bgpio_get_set;
-		if (!gc->be_bits)
-			gc->get_multiple = bgpio_get_set_multiple;
+		/* if the direction inverted */
+		if (flags & BGPIOF_INVERTED_REG_DIR) {
+			gc->get = bgpio_get_set_inv_dir;
+			if (!gc->be_bits)
+				gc->get_multiple =
+				bgpio_get_set_multiple_inv_dir;
+		} else {
+			gc->get = bgpio_get_set;
+			if (!gc->be_bits)
+				gc->get_multiple = bgpio_get_set_multiple;
+		}
 		/*
 		 * We deliberately avoid assigning the ->get_multiple() call
 		 * for big endian mirrored registers which are ALSO reflecting
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 5382b5183b7e..63570580707c 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -425,6 +425,7 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
 #define BGPIOF_BIG_ENDIAN_BYTE_ORDER	BIT(3)
 #define BGPIOF_READ_OUTPUT_REG_SET	BIT(4) /* reg_set stores output value */
 #define BGPIOF_NO_OUTPUT		BIT(5) /* only input */
+#define BGPIOF_INVERTED_REG_DIR		BIT(6) /* reg_dir inverted */
 
 #endif
 
-- 
2.14.1

Re: [PATCH v1 1/1] gpio: mmio: add inverted direction get_set io support

[Andy Shevchenko]

On Mon, Jul 30, 2018 at 12:34 PM, Tomer Maimon <tmaimon77@gmail.com> wrote:
> Add get_set_inv_dir and get_set_multiple_inv_dir I/O functions
> to call the data register when the dirction is input and
> set register when the direction is output.
> the functions will linked to the I/O get functions if the user set
> BGPIOF_INVERTED_REG_DIR flag in the bgpio initialization.

> +       /* Make sure we first clear any bits that are zero when we read the register */
> +       *bits &= ~*mask;

Theoretically it's possible to get mask and bits longer than one long,
and bitmap API has to be used.
Though, it seems entire driver has been written in an assumption that
it's never happen.

> +                               gc->get_multiple =
> +                               bgpio_get_set_multiple_inv_dir;

I think you may keep it on one line.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 1/1] gpio: mmio: add inverted direction get_set io support

[Linus Walleij]

On Mon, Jul 30, 2018 at 11:34 AM Tomer Maimon <tmaimon77@gmail.com> wrote:

> Add get_set_inv_dir and get_set_multiple_inv_dir I/O functions
> to call the data register when the dirction is input and
> set register when the direction is output.
> the functions will linked to the I/O get functions if the user set
> BGPIOF_INVERTED_REG_DIR flag in the bgpio initialization.
>
> Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>

I think you uncovered a bug. This is however not the best fix IMO.

Sorry for not understanding the issue at first, I am sometimes
pretty slow in the head. :(

I'm sending a patch that I hope fixes the real problem in an
elegant way, and makes it possible to just define dirin and
BGPIOF_READ_OUTPUT_REG_SET.

Yours,
Linus Walleij