[PATCH 05/33] gpio: add generic single-register fixed-direction GPIO driver

Russell King
2016-08-29T10:24:31Z

Add a simple, generic, single register fixed-direction GPIO driver.
This is able to support a single register where a fixed number of
bits are used for input and a fixed number of bits used for output.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
---
drivers/gpio/Kconfig | 6 ++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-reg.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/gpio-reg.h | 12 ++++
4 files changed, 158 insertions(+)
create mode 100644 drivers/gpio/gpio-reg.c
create mode 100644 include/linux/gpio-reg.h

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 98dd47a30fc7..49bd8b89712e 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -365,6 +365,12 @@ config GPIO_RCAR
help
Say yes here to support GPIO on Renesas R-Car SoCs.

+config GPIO_REG
+ bool
+ help
+ A 32-bit single register GPIO fixed in/out implementation. This
+ can be used to represent any register as a set of GPIO signals.
+
config GPIO_SPEAR_SPICS
bool "ST SPEAr13xx SPI Chip Select as GPIO support"
depends on PLAT_SPEAR
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 2a035ed8f168..3fc904fcc595 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_GPIO_PXA) += gpio-pxa.o
obj-$(CONFIG_GPIO_RC5T583) += gpio-rc5t583.o
obj-$(CONFIG_GPIO_RDC321X) += gpio-rdc321x.o
obj-$(CONFIG_GPIO_RCAR) += gpio-rcar.o
+obj-$(CONFIG_GPIO_REG) += gpio-reg.o
obj-$(CONFIG_ARCH_SA1100) += gpio-sa1100.o
obj-$(CONFIG_GPIO_SCH) += gpio-sch.o
obj-$(CONFIG_GPIO_SCH311X) += gpio-sch311x.o
diff --git a/drivers/gpio/gpio-reg.c b/drivers/gpio/gpio-reg.c
new file mode 100644
index 000000000000..fc7e0a395f9f
--- /dev/null
+++ b/drivers/gpio/gpio-reg.c
@@ -0,0 +1,139 @@
+#include <linux/gpio/driver.h>
+#include <linux/gpio-reg.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+struct gpio_reg {
+ struct gpio_chip gc;
+ spinlock_t lock;
+ u32 direction;
+ u32 out;
+ void __iomem *reg;
+};
+
+#define to_gpio_reg(x) container_of(x, struct gpio_reg, gc)
+
+static int gpio_reg_get_direction(struct gpio_chip *gc, unsigned offset)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+
+ return r->direction & BIT(offset) ? 1 : 0;
+}
+
+static int gpio_reg_direction_output(struct gpio_chip *gc, unsigned offset,
+ int value)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+
+ if (r->direction & BIT(offset))
+ return -ENOTSUPP;
+
+ gc->set(gc, offset, value);
+ return 0;
+}
+
+static int gpio_reg_direction_input(struct gpio_chip *gc, unsigned offset)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+
+ return r->direction & BIT(offset) ? 0 : -ENOTSUPP;
+}
+
+static void gpio_reg_set(struct gpio_chip *gc, unsigned offset, int value)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+ unsigned long flags;
+ u32 val, mask = BIT(offset);
+
+ spin_lock_irqsave(&r->lock, flags);
+ val = r->out;
+ if (value)
+ val |= mask;
+ else
+ val &= ~mask;
+ r->out = val;
+ writel_relaxed(val, r->reg);
+ spin_unlock_irqrestore(&r->lock, flags);
+}
+
+static int gpio_reg_get(struct gpio_chip *gc, unsigned offset)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+ u32 val, mask = BIT(offset);
+
+ if (r->direction & mask) {
+ /*
+ * double-read the value, some registers latch after the
+ * first read.
+ */
+ readl_relaxed(r->reg);
+ val = readl_relaxed(r->reg);
+ } else {
+ val = r->out;
+ }
+ return !!(val & mask);
+}
+
+static void gpio_reg_set_multiple(struct gpio_chip *gc, unsigned long *mask,
+ unsigned long *bits)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+ unsigned long flags;
+
+ spin_lock_irqsave(&r->lock, flags);
+ r->out = (r->out & ~*mask) | *bits;
+ writel_relaxed(r->out, r->reg);
+ spin_unlock_irqrestore(&r->lock, flags);
+}
+
+struct gpio_chip *gpio_reg_init(struct device *dev, void __iomem *reg,
+ int base, int num, const char *label, u32 direction, u32 def_out,
+ const char *const *names)
+{
+ struct gpio_reg *r;
+ int ret;
+
+ if (dev)
+ r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
+ else
+ r = kzalloc(sizeof(*r), GFP_KERNEL);
+
+ if (!r)
+ return ERR_PTR(-ENOMEM);
+
+ spin_lock_init(&r->lock);
+
+ r->gc.label = label;
+ r->gc.get_direction = gpio_reg_get_direction;
+ r->gc.direction_input = gpio_reg_direction_input;
+ r->gc.direction_output = gpio_reg_direction_output;
+ r->gc.set = gpio_reg_set;
+ r->gc.get = gpio_reg_get;
+ r->gc.set_multiple = gpio_reg_set_multiple;
+ r->gc.base = base;
+ r->gc.ngpio = num;
+ r->gc.names = names;
+ r->direction = direction;
+ r->out = def_out;
+ r->reg = reg;
+
+ if (dev)
+ ret = devm_gpiochip_add_data(dev, &r->gc, r);
+ else
+ ret = gpiochip_add_data(&r->gc, r);
+
+ return ret ? ERR_PTR(ret) : &r->gc;
+}
+
+int gpio_reg_resume(struct gpio_chip *gc)
+{
+ struct gpio_reg *r = to_gpio_reg(gc);
+ unsigned long flags;
+
+ spin_lock_irqsave(&r->lock, flags);
+ writel_relaxed(r->out, r->reg);
+ spin_unlock_irqrestore(&r->lock, flags);
+
+ return 0;
+}
diff --git a/include/linux/gpio-reg.h b/include/linux/gpio-reg.h
new file mode 100644
index 000000000000..0352bec7319a
--- /dev/null
+++ b/include/linux/gpio-reg.h
@@ -0,0 +1,12 @@
+#ifndef GPIO_REG_H
+#define GPIO_REG_H
+
+struct device;
+
+struct gpio_chip *gpio_reg_init(struct device *dev, void __iomem *reg,
+ int base, int num, const char *label, u32 direction, u32 def_out,
+ const char *const *names);
+
+int gpio_reg_resume(struct gpio_chip *gc);
+
+#endif
--
2.1.0