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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.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
new file mode 100644
index 000000000..487577d22
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Backlight emulation LED trigger
+ *
+ * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>
+ * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>
+ */
+
+#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;
+ int new_status;
+
+ /* If we aren't interested in this event, skip it immediately ... */
+ if (event != FB_EVENT_BLANK)
+ return 0;
+
+ blank = fb_event->data;
+ new_status = *blank ? BLANK : UNBLANK;
+
+ if (new_status == n->old_status)
+ return 0;
+
+ if ((n->old_status == UNBLANK) ^ n->invert) {
+ n->brightness = led->brightness;
+ led_set_brightness_nosleep(led, LED_OFF);
+ } else {
+ led_set_brightness_nosleep(led, n->brightness);
+ }
+
+ n->old_status = new_status;
+
+ return 0;
+}
+
+static ssize_t bl_trig_invert_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct bl_trig_notifier *n = led_trigger_get_drvdata(dev);
+
+ 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 = led_trigger_get_led(dev);
+ struct bl_trig_notifier *n = led_trigger_get_drvdata(dev);
+ 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_nosleep(led, LED_OFF);
+ else
+ led_set_brightness_nosleep(led, n->brightness);
+
+ return num;
+}
+static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);
+
+static struct attribute *bl_trig_attrs[] = {
+ &dev_attr_inverted.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(bl_trig);
+
+static int bl_trig_activate(struct led_classdev *led)
+{
+ int ret;
+
+ struct bl_trig_notifier *n;
+
+ n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
+ if (!n)
+ return -ENOMEM;
+ led_set_trigger_data(led, n);
+
+ 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");
+
+ return 0;
+}
+
+static void bl_trig_deactivate(struct led_classdev *led)
+{
+ struct bl_trig_notifier *n = led_get_trigger_data(led);
+
+ fb_unregister_client(&n->notifier);
+ kfree(n);
+}
+
+static struct led_trigger bl_led_trigger = {
+ .name = "backlight",
+ .activate = bl_trig_activate,
+ .deactivate = bl_trig_deactivate,
+ .groups = bl_trig_groups,
+};
+module_led_trigger(bl_led_trigger);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("Backlight emulation LED trigger");
+MODULE_LICENSE("GPL v2");