gpio: sch311x: Use RMW to change direction

Bit 0 in the config register obviously controls the direction
of the GPIO so instead of hammering 0x0/0x1 into that register,
use read-modify-write so that we can also alter the other bits
in the register.

Cc: Bruno Randolf <br1@einfach.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-sch311x.c b/drivers/gpio/gpio-sch311x.c
index ed64f7fa23b1c7d70838f4a53102afe11f1532af..faf44178f97b259d6e67a2258fe2158f5d815f1e 100644 (file)
--- a/drivers/gpio/gpio-sch311x.c
+++ b/drivers/gpio/gpio-sch311x.c
@@ -23,10 +23,9 @@
 
 #define DRV_NAME                       "gpio-sch311x"
 
-#define SCH311X_GPIO_CONF_OUT          0x00
-#define SCH311X_GPIO_CONF_IN           0x01
-#define SCH311X_GPIO_CONF_INVERT       0x02
-#define SCH311X_GPIO_CONF_OPEN_DRAIN   0x80
+#define SCH311X_GPIO_CONF_DIR          BIT(0)
+#define SCH311X_GPIO_CONF_INVERT       BIT(1)
+#define SCH311X_GPIO_CONF_OPEN_DRAIN   BIT(7)
 
 #define SIO_CONFIG_KEY_ENTER           0x55
 #define SIO_CONFIG_KEY_EXIT            0xaa
@@ -196,10 +195,12 @@ static void sch311x_gpio_set(struct gpio_chip *chip, unsigned offset,
 static int sch311x_gpio_direction_in(struct gpio_chip *chip, unsigned offset)
 {
        struct sch311x_gpio_block *block = gpiochip_get_data(chip);
+       unsigned char data;
 
        spin_lock(&block->lock);
-       outb(SCH311X_GPIO_CONF_IN, block->runtime_reg +
-            block->config_regs[offset]);
+       data = inb(block->runtime_reg + block->config_regs[offset]);
+       data |= SCH311X_GPIO_CONF_DIR;
+       outb(data, block->runtime_reg + block->config_regs[offset]);
        spin_unlock(&block->lock);
 
        return 0;
@@ -209,12 +210,13 @@ static int sch311x_gpio_direction_out(struct gpio_chip *chip, unsigned offset,
                                      int value)
 {
        struct sch311x_gpio_block *block = gpiochip_get_data(chip);
+       unsigned char data;
 
        spin_lock(&block->lock);
 
-       outb(SCH311X_GPIO_CONF_OUT, block->runtime_reg +
-            block->config_regs[offset]);
-
+       data = inb(block->runtime_reg + block->config_regs[offset]);
+       data &= ~SCH311X_GPIO_CONF_DIR;
+       outb(data, block->runtime_reg + block->config_regs[offset]);
        __sch311x_gpio_set(block, offset, value);
 
        spin_unlock(&block->lock);
@@ -230,7 +232,7 @@ static int sch311x_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
        data = inb(block->runtime_reg + block->config_regs[offset]);
        spin_unlock(&block->lock);
 
-       return !!(data & SCH311X_GPIO_CONF_IN);
+       return !!(data & SCH311X_GPIO_CONF_DIR);
 }
 
 static int sch311x_gpio_probe(struct platform_device *pdev)