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path: root/drivers/leds/trigger/ledtrig-backlight.c
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Diffstat (limited to 'drivers/leds/trigger/ledtrig-backlight.c')
-rw-r--r--drivers/leds/trigger/ledtrig-backlight.c166
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
new file mode 100644
index 000000000000..3c9c88a07eb8
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -0,0 +1,166 @@
+/*
+ * Backlight emulation LED trigger
+ *
+ * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>
+ * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/fb.h>
+#include <linux/leds.h>
+#include "../leds.h"
+
+#define BLANK 1
+#define UNBLANK 0
+
+struct bl_trig_notifier {
+ struct led_classdev *led;
+ int brightness;
+ int old_status;
+ struct notifier_block notifier;
+ unsigned invert;
+};
+
+static int fb_notifier_callback(struct notifier_block *p,
+ unsigned long event, void *data)
+{
+ struct bl_trig_notifier *n = container_of(p,
+ struct bl_trig_notifier, notifier);
+ 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 (new_status == n->old_status)
+ break;
+
+ if ((n->old_status == UNBLANK) ^ n->invert) {
+ n->brightness = led->brightness;
+ __led_set_brightness(led, LED_OFF);
+ } else {
+ __led_set_brightness(led, n->brightness);
+ }
+
+ 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 = kstrtoul(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;
+
+ struct bl_trig_notifier *n;
+
+ n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
+ led->trigger_data = n;
+ if (!n) {
+ dev_err(led->dev, "unable to allocate backlight trigger\n");
+ 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;
+ n->notifier.notifier_call = fb_notifier_callback;
+
+ ret = fb_register_client(&n->notifier);
+ if (ret)
+ dev_err(led->dev, "unable to register backlight trigger\n");
+ led->activated = true;
+
+ return;
+
+err_invert:
+ led->trigger_data = NULL;
+ kfree(n);
+}
+
+static void bl_trig_deactivate(struct led_classdev *led)
+{
+ struct bl_trig_notifier *n =
+ (struct bl_trig_notifier *) led->trigger_data;
+
+ if (led->activated) {
+ device_remove_file(led->dev, &dev_attr_inverted);
+ fb_unregister_client(&n->notifier);
+ kfree(n);
+ led->activated = false;
+ }
+}
+
+static struct led_trigger bl_led_trigger = {
+ .name = "backlight",
+ .activate = bl_trig_activate,
+ .deactivate = bl_trig_deactivate
+};
+
+static int __init bl_trig_init(void)
+{
+ return led_trigger_register(&bl_led_trigger);
+}
+
+static void __exit bl_trig_exit(void)
+{
+ led_trigger_unregister(&bl_led_trigger);
+}
+
+module_init(bl_trig_init);
+module_exit(bl_trig_exit);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("Backlight emulation LED trigger");
+MODULE_LICENSE("GPL v2");