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Subject[PATCH 1/2] gpio: mmio: introduce BGPIOF_NO_SET_ON_INPUT
Date
Some gpio controllers ignores pin value writing when that pin is
configured as input mode. As a result, bgpio_dir_out should set
pin to output before configuring pin values or gpio pin values
can't be set up properly.
Introduce two variants of bgpio_dir_out: bgpio_dir_out_val_first
and bgpio_dir_out_dir_first, and assign direction_output according
to a new flag: BGPIOF_NO_SET_ON_INPUT.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
---
drivers/gpio/gpio-mmio.c | 23 +++++++++++++++++++----
include/linux/gpio/driver.h | 1 +
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c
index f729e3e9e983..b778f33cc6af 100644
--- a/drivers/gpio/gpio-mmio.c
+++ b/drivers/gpio/gpio-mmio.c
@@ -389,12 +389,10 @@ static int bgpio_get_dir(struct gpio_chip *gc, unsigned int gpio)
return GPIO_LINE_DIRECTION_IN;
}

-static int bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
+static void bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
{
unsigned long flags;

- gc->set(gc, gpio, val);
-
spin_lock_irqsave(&gc->bgpio_lock, flags);

gc->bgpio_dir |= bgpio_line2mask(gc, gpio);
@@ -405,7 +403,21 @@ static int bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
gc->write_reg(gc->reg_dir_out, gc->bgpio_dir);

spin_unlock_irqrestore(&gc->bgpio_lock, flags);
+}

+static int bgpio_dir_out_dir_first(struct gpio_chip *gc, unsigned int gpio,
+ int val)
+{
+ bgpio_dir_out(gc, gpio, val);
+ gc->set(gc, gpio, val);
+ return 0;
+}
+
+static int bgpio_dir_out_val_first(struct gpio_chip *gc, unsigned int gpio,
+ int val)
+{
+ gc->set(gc, gpio, val);
+ bgpio_dir_out(gc, gpio, val);
return 0;
}

@@ -538,7 +550,10 @@ static int bgpio_setup_direction(struct gpio_chip *gc,
if (dirout || dirin) {
gc->reg_dir_out = dirout;
gc->reg_dir_in = dirin;
- gc->direction_output = bgpio_dir_out;
+ if (flags & BGPIOF_NO_SET_ON_INPUT)
+ gc->direction_output = bgpio_dir_out_dir_first;
+ else
+ gc->direction_output = bgpio_dir_out_val_first;
gc->direction_input = bgpio_dir_in;
gc->get_direction = bgpio_get_dir;
} else {
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 6ef05bccc0a6..ed65e00ee977 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -572,6 +572,7 @@ 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_NO_SET_ON_INPUT BIT(6)

int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hwirq);
--
2.24.1
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