[U-Boot] [PATCH v2] gpio: spear_gpio: Fix gpio_set_value() implementation

[Axel Lin <axel.lin@ingics.com>]

In current gpio_set_value() implementation, it always sets the gpio control bit
no matter the value argument is 0 or 1. Thus the GPIOs never set to low.
This patch fixes this bug.

The address bus is used as a mask on read/write operations, so that independent
software drivers can set their GPIO bits without affecting any other pins in a
single write operation. Thus we don't need a read-modify-write to update the
register.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Stefan Roese <sr@denx.de>
Reviewed-by: Vipin Kumar <vipin.kumar@st.com>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
---
v2: Update commit log to explain why a read-modify-write is not necessary
    for clearing specific GPIO bit.
    Also added Michael Trimarchi's reviewed-by tag since he does review the
    patch and said the patch is fine.

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/spear_gpio.c b/drivers/gpio/spear_gpio.c
index 367b670..6fb4117 100644
--- a/drivers/gpio/spear_gpio.c
+++ b/drivers/gpio/spear_gpio.c
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {
 	struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-	writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+	if (value)
+		writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+	else
+		writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
 	return 0;
 }
-- 
1.8.1.2