fujitsu-laptop: Add support for eco LED

There is an indicator LED signaling activated power saving mode
on certain Fujitsu laptop models. This has currently no use on Linux.
Export it to userspace.
Signed-off-by: Matej Groma <matejgroma@gmail.com>
Acked-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

drivers/platform/x86/fujitsu-laptop.c

@@ -105,6 +105,8 @@
 #define LOGOLAMP_POWERON 0x2000
 #define LOGOLAMP_ALWAYS  0x4000
 #define RADIO_LED_ON	0x20
+#define ECO_LED	0x10000
+#define ECO_LED_ON	0x80000
 #endif
 
 /* Hotkey details */
@@ -166,6 +168,7 @@ struct fujitsu_hotkey_t {
 	int logolamp_registered;
 	int kblamps_registered;
 	int radio_led_registered;
+	int eco_led_registered;
 };
 
 static struct fujitsu_hotkey_t *fujitsu_hotkey;
@@ -202,6 +205,17 @@ static struct led_classdev radio_led = {
  .brightness_get = radio_led_get,
  .brightness_set = radio_led_set
 };
+
+static enum led_brightness eco_led_get(struct led_classdev *cdev);
+static void eco_led_set(struct led_classdev *cdev,
+			       enum led_brightness brightness);
+
+static struct led_classdev eco_led = {
+ .name = "fujitsu::eco_led",
+ .max_brightness = 1,
+ .brightness_get = eco_led_get,
+ .brightness_set = eco_led_set
+};
 #endif
 
 #ifdef CONFIG_FUJITSU_LAPTOP_DEBUG
@@ -286,6 +300,18 @@ static void radio_led_set(struct led_classdev *cdev,
 		call_fext_func(FUNC_RFKILL, 0x5, RADIO_LED_ON, 0x0);
 }
 
+static void eco_led_set(struct led_classdev *cdev,
+				enum led_brightness brightness)
+{
+	int curr;
+
+	curr = call_fext_func(FUNC_LEDS, 0x2, ECO_LED, 0x0);
+	if (brightness)
+		call_fext_func(FUNC_LEDS, 0x1, ECO_LED, curr | ECO_LED_ON);
+	else
+		call_fext_func(FUNC_LEDS, 0x1, ECO_LED, curr & ~ECO_LED_ON);
+}
+
 static enum led_brightness logolamp_get(struct led_classdev *cdev)
 {
 	enum led_brightness brightness = LED_OFF;
@@ -320,6 +346,16 @@ static enum led_brightness radio_led_get(struct led_classdev *cdev)
 
 	return brightness;
 }
+
+static enum led_brightness eco_led_get(struct led_classdev *cdev)
+{
+	enum led_brightness brightness = LED_OFF;
+
+	if (call_fext_func(FUNC_LEDS, 0x2, ECO_LED, 0x0) & ECO_LED_ON)
+		brightness = cdev->max_brightness;
+
+	return brightness;
+}
 #endif
 
 /* Hardware access for LCD brightness control */
@@ -934,6 +970,23 @@ static int acpi_fujitsu_hotkey_add(struct acpi_device *device)
 			       result);
 		}
 	}
+
+	/* Support for eco led is not always signaled in bit corresponding
+	 * to the bit used to control the led. According to the DSDT table,
+	 * bit 14 seems to indicate presence of said led as well.
+	 * Confirm by testing the status.
+	*/
+	if ((call_fext_func(FUNC_LEDS, 0x0, 0x0, 0x0) & BIT(14)) &&
+	   (call_fext_func(FUNC_LEDS, 0x2, ECO_LED, 0x0) != UNSUPPORTED_CMD)) {
+		result = led_classdev_register(&fujitsu->pf_device->dev,
+						&eco_led);
+		if (result == 0) {
+			fujitsu_hotkey->eco_led_registered = 1;
+		} else {
+			pr_err("Could not register LED handler for eco LED, error %i\n",
+			       result);
+		}
+	}
 #endif
 
 	return result;
@@ -963,6 +1016,9 @@ static int acpi_fujitsu_hotkey_remove(struct acpi_device *device)
 
 	if (fujitsu_hotkey->radio_led_registered)
 		led_classdev_unregister(&radio_led);
+
+	if (fujitsu_hotkey->eco_led_registered)
+		led_classdev_unregister(&eco_led);
 #endif
 
 	input_unregister_device(input);