[PATCH 1/2] gpio: mmio: introduce BGPIOF_NO_SET_ON_INPUT

[Chuanhong Guo]

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@xxxxxxxxx>
---
 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