[v3] LEDS: Add output invertion option to backlight trigger

Commit Message

Janusz Krzysztofik Jan. 10, 2011, 4:54 a.m. UTC

None

Patch

--- linux-2.6.37/drivers/leds/ledtrig-backlight.c.orig	2011-01-10 02:55:26.000000000 +0100
+++ linux-2.6.37/drivers/leds/ledtrig-backlight.c	2011-01-10 03:12:46.000000000 +0100
@@ -26,6 +26,7 @@  struct bl_trig_notifier {
 	int brightness;
 	int old_status;
 	struct notifier_block notifier;
+	unsigned invert;
 };
 
 static int fb_notifier_callback(struct notifier_block *p,
@@ -36,23 +37,64 @@  static int fb_notifier_callback(struct n
 	struct led_classdev *led = n->led;
 	struct fb_event *fb_event = data;
 	int *blank = fb_event->data;
+	int new_status = *blank ? BLANK : UNBLANK;
 
 	switch (event) {
 	case FB_EVENT_BLANK :
-		if (*blank && n->old_status == UNBLANK) {
+		if (new_status == n->old_status)
+			break;
+
+		if ((n->old_status == UNBLANK) ^ n->invert) {
 			n->brightness = led->brightness;
 			led_set_brightness(led, LED_OFF);
-			n->old_status = BLANK;
-		} else if (!*blank && n->old_status == BLANK) {
+		} else {
 			led_set_brightness(led, n->brightness);
-			n->old_status = UNBLANK;
 		}
+
+		n->old_status = new_status;
+
 		break;
 	}
 
 	return 0;
 }
 
+static ssize_t bl_trig_invert_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led = dev_get_drvdata(dev);
+	struct bl_trig_notifier *n = led->trigger_data;
+
+	return sprintf(buf, "%u\n", n->invert);
+}
+
+static ssize_t bl_trig_invert_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t num)
+{
+	struct led_classdev *led = dev_get_drvdata(dev);
+	struct bl_trig_notifier *n = led->trigger_data;
+	unsigned long invert;
+	int ret;
+
+	ret = strict_strtoul(buf, 10, &invert);
+	if (ret < 0)
+		return ret;
+
+	if (invert > 1)
+		return -EINVAL;
+
+	n->invert = invert;
+
+	/* After inverting, we need to update the LED. */
+	if ((n->old_status == BLANK) ^ n->invert)
+		led_set_brightness(led, LED_OFF);
+	else
+		led_set_brightness(led, n->brightness);
+
+	return num;
+}
+static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);
+
 static void bl_trig_activate(struct led_classdev *led)
 {
 	int ret;
@@ -66,6 +108,10 @@  static void bl_trig_activate(struct led_
 		return;
 	}
 
+	ret = device_create_file(led->dev, &dev_attr_inverted);
+	if (ret)
+		goto err_invert;
+
 	n->led = led;
 	n->brightness = led->brightness;
 	n->old_status = UNBLANK;
@@ -74,6 +120,12 @@  static void bl_trig_activate(struct led_
 	ret = fb_register_client(&n->notifier);
 	if (ret)
 		dev_err(led->dev, "unable to register backlight trigger\n");
+
+	return;
+
+err_invert:
+	led->trigger_data = NULL;
+	kfree(n);
 }
 
 static void bl_trig_deactivate(struct led_classdev *led)
@@ -82,6 +134,7 @@  static void bl_trig_deactivate(struct le
 		(struct bl_trig_notifier *) led->trigger_data;
 
 	if (n) {
+		device_remove_file(led->dev, &dev_attr_inverted);
 		fb_unregister_client(&n->notifier);
 		kfree(n);
 	}
--- linux-2.6.37/Documentation/ABI/testing/sysfs-class-led.orig	2011-01-10 02:42:16.000000000 +0100
+++ linux-2.6.37/Documentation/ABI/testing/sysfs-class-led	2011-01-10 03:38:28.000000000 +0100
@@ -26,3 +26,13 @@  Description:
 		scheduler is chosen. Trigger specific parameters can appear in
 		/sys/class/leds/<led> once a given trigger is selected.
 
+What:		/sys/class/leds/<led>/inverted
+Date:		January 2011
+KernelVersion:	2.6.38
+Contact:	Richard Purdie <[e-mail]>
+Description:
+		Invert the LED on/off state. This parameter is specific to
+		gpio and backlight triggers. In case of the backlight trigger,
+		it is usefull when driving a LED which is intended to indicate
+		a device in a standby like state.
+