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Subject[PATCH 2/3] gpio: generic: support input-only chips
Date
Allow chips to indicates that they are input-only and thus cannot set
the output value. This will be used by the gpio-etraxfs driver.

Signed-off-by: Rabin Vincent <rabin@rab.in>
---
drivers/gpio/gpio-generic.c | 23 ++++++++++++++++++++---
include/linux/basic_mmio_gpio.h | 1 +
2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
index 9bda372..b3debbf 100644
--- a/drivers/gpio/gpio-generic.c
+++ b/drivers/gpio/gpio-generic.c
@@ -153,6 +153,10 @@ static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
return !!(bgc->read_reg(bgc->reg_dat) & bgc->pin2mask(bgc, gpio));
}

+static void bgpio_set_none(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+}
+
static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
{
struct bgpio_chip *bgc = to_bgpio_chip(gc);
@@ -279,6 +283,12 @@ static int bgpio_simple_dir_in(struct gpio_chip *gc, unsigned int gpio)
return 0;
}

+static int bgpio_dir_out_err(struct gpio_chip *gc, unsigned int gpio,
+ int val)
+{
+ return -EINVAL;
+}
+
static int bgpio_simple_dir_out(struct gpio_chip *gc, unsigned int gpio,
int val)
{
@@ -444,6 +454,9 @@ static int bgpio_setup_io(struct bgpio_chip *bgc,
bgc->reg_set = set;
bgc->gc.set = bgpio_set_set;
bgc->gc.set_multiple = bgpio_set_multiple_set;
+ } else if (flags & BGPIOF_NO_OUTPUT) {
+ bgc->gc.set = bgpio_set_none;
+ bgc->gc.set_multiple = NULL;
} else {
bgc->gc.set = bgpio_set;
bgc->gc.set_multiple = bgpio_set_multiple;
@@ -460,7 +473,8 @@ static int bgpio_setup_io(struct bgpio_chip *bgc,

static int bgpio_setup_direction(struct bgpio_chip *bgc,
void __iomem *dirout,
- void __iomem *dirin)
+ void __iomem *dirin,
+ unsigned long flags)
{
if (dirout && dirin) {
return -EINVAL;
@@ -473,7 +487,10 @@ static int bgpio_setup_direction(struct bgpio_chip *bgc,
bgc->gc.direction_output = bgpio_dir_out_inv;
bgc->gc.direction_input = bgpio_dir_in_inv;
} else {
- bgc->gc.direction_output = bgpio_simple_dir_out;
+ if (flags & BGPIOF_NO_OUTPUT)
+ bgc->gc.direction_output = bgpio_dir_out_err;
+ else
+ bgc->gc.direction_output = bgpio_simple_dir_out;
bgc->gc.direction_input = bgpio_simple_dir_in;
}

@@ -525,7 +542,7 @@ int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
if (ret)
return ret;

- ret = bgpio_setup_direction(bgc, dirout, dirin);
+ ret = bgpio_setup_direction(bgc, dirout, dirin, flags);
if (ret)
return ret;

diff --git a/include/linux/basic_mmio_gpio.h b/include/linux/basic_mmio_gpio.h
index 14eea94..ed3768f 100644
--- a/include/linux/basic_mmio_gpio.h
+++ b/include/linux/basic_mmio_gpio.h
@@ -75,5 +75,6 @@ int bgpio_init(struct bgpio_chip *bgc, struct device *dev,
#define BGPIOF_UNREADABLE_REG_DIR BIT(2) /* reg_dir is unreadable */
#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 */

#endif /* __BASIC_MMIO_GPIO_H */
--
2.1.4


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