gpio_led: add support for inverted polarity

Some GPIO connected LEDs have inverted polarity.
Introduce new config option: CONFIG_GPIO_LED_INVERTED_TABLE for the
specifying the inverted GPIO LEDs list and add support for this in the
gpio_led driver.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Tested-by: Ilya Ledvich <ilya@compulab.co.il>

README

@@ -1971,6 +1971,13 @@ CBFS (Coreboot Filesystem) support
 		status LED backend implementation. Define CONFIG_GPIO_LED
 		to include the gpio_led driver in the U-Boot binary.
 
+		CONFIG_GPIO_LED_INVERTED_TABLE
+		Some GPIO connected LEDs may have inverted polarity in which
+		case the GPIO high value corresponds to LED off state and
+		GPIO low value corresponds to LED on state.
+		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
+		with a list of GPIO LEDs that have inverted polarity.
+
 - CAN Support:	CONFIG_CAN_DRIVER
 
 		Defining CONFIG_CAN_DRIVER enables CAN driver support

drivers/misc/gpio_led.c

@@ -9,19 +9,42 @@
 #include <status_led.h>
 #include <asm/gpio.h>
 
+#ifndef CONFIG_GPIO_LED_INVERTED_TABLE
+#define CONFIG_GPIO_LED_INVERTED_TABLE {}
+#endif
+
+static led_id_t gpio_led_inv[] = CONFIG_GPIO_LED_INVERTED_TABLE;
+
+static int gpio_led_gpio_value(led_id_t mask, int state)
+{
+	int i, gpio_value = (state == STATUS_LED_ON);
+
+	for (i = 0; i < ARRAY_SIZE(gpio_led_inv); i++) {
+		if (gpio_led_inv[i] == mask)
+			gpio_value = !gpio_value;
+	}
+
+	return gpio_value;
+}
+
 void __led_init(led_id_t mask, int state)
 {
+	int gpio_value;
+
 	if (gpio_request(mask, "gpio_led") != 0) {
 		printf("%s: failed requesting GPIO%lu!\n", __func__, mask);
 		return;
 	}
 
-	gpio_direction_output(mask, state == STATUS_LED_ON);
+	gpio_value = gpio_led_gpio_value(mask, state);
+	gpio_direction_output(mask, gpio_value);
 }
 
 void __led_set(led_id_t mask, int state)
 {
-	gpio_set_value(mask, state == STATUS_LED_ON);
+	int gpio_value = gpio_led_gpio_value(mask, state);
+
+	gpio_set_value(mask, gpio_value);
 }
 
 void __led_toggle(led_id_t mask)