realtek: ensure output drivers are enabled in RTL8231

The bootloader can leave the GPIO expander in a state which doesn't have
output drivers enabled so GPIOs will properly work for input but output
operations will have no effect.

To avoid disrupting the boot in case the bootloader left direction and
data registers in an inconsistent state (e.g. pulling SoC's reset to 0)
reconfigure everything as input.

Reviewed-by: Sander Vanheule <[email protected]>
Signed-off-by: Paul Fertser <[email protected]>

target/linux/realtek/files-5.10/drivers/gpio/gpio-rtl8231.c

@@ -239,8 +239,6 @@ void rtl8231_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
 
 int rtl8231_init(struct rtl8231_gpios *gpios)
 {
-	u32 v;
-
 	pr_info("%s called, MDIO bus ID: %d\n", __func__, gpios->smi_bus_id);
 
 	gpios->reg_cached = 0;
@@ -254,11 +252,15 @@ int rtl8231_init(struct rtl8231_gpios *gpios)
 		sw_w32_mask(3, 1, RTL838X_DMY_REG5);
 	}
 
-	/* Select GPIO functionality for pins 0-34 */
+	/* Select GPIO functionality and force input direction for pins 0-36 */
 	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(0), 0xffff);
+	rtl8231_write(gpios, RTL8231_GPIO_DIR(0), 0xffff);
 	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(16), 0xffff);
-	v = rtl8231_read(gpios, RTL8231_GPIO_PIN_SEL(32));
-	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(32), v | 0x7);
+	rtl8231_write(gpios, RTL8231_GPIO_DIR(16), 0xffff);
+	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(32), 0x03ff);
+
+	/* Set LED_Start to enable drivers for output mode */
+	rtl8231_write(gpios, RTL8231_LED_FUNC0, 1 << 1);
 
 	return 0;
 }

target/linux/realtek/files-5.4/drivers/gpio/gpio-rtl8231.c

@@ -239,8 +239,6 @@ void rtl8231_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
 
 int rtl8231_init(struct rtl8231_gpios *gpios)
 {
-	u32 v;
-
 	pr_info("%s called, MDIO bus ID: %d\n", __func__, gpios->smi_bus_id);
 
 	gpios->reg_cached = 0;
@@ -254,11 +252,15 @@ int rtl8231_init(struct rtl8231_gpios *gpios)
 		sw_w32_mask(3, 1, RTL838X_DMY_REG5);
 	}
 
-	/* Select GPIO functionality for pins 0-34 */
+	/* Select GPIO functionality and force input direction for pins 0-36 */
 	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(0), 0xffff);
+	rtl8231_write(gpios, RTL8231_GPIO_DIR(0), 0xffff);
 	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(16), 0xffff);
-	v = rtl8231_read(gpios, RTL8231_GPIO_PIN_SEL(32));
-	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(32), v | 0x7);
+	rtl8231_write(gpios, RTL8231_GPIO_DIR(16), 0xffff);
+	rtl8231_write(gpios, RTL8231_GPIO_PIN_SEL(32), 0x03ff);
+
+	/* Set LED_Start to enable drivers for output mode */
+	rtl8231_write(gpios, RTL8231_LED_FUNC0, 1 << 1);
 
 	return 0;
 }