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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Backlight emulation LED trigger4 *5 * Copyright 2008 (C) Rodolfo Giometti <giometti@linux.it>6 * Copyright 2008 (C) Eurotech S.p.A. <info@eurotech.it>7 */8 9#include <linux/module.h>10#include <linux/kernel.h>11#include <linux/slab.h>12#include <linux/init.h>13#include <linux/fb.h>14#include <linux/leds.h>15#include "../leds.h"16 17#define BLANK 118#define UNBLANK 019 20struct bl_trig_notifier {21 struct led_classdev *led;22 int brightness;23 int old_status;24 struct notifier_block notifier;25 unsigned invert;26};27 28static int fb_notifier_callback(struct notifier_block *p,29 unsigned long event, void *data)30{31 struct bl_trig_notifier *n = container_of(p,32 struct bl_trig_notifier, notifier);33 struct led_classdev *led = n->led;34 struct fb_event *fb_event = data;35 int *blank;36 int new_status;37 38 /* If we aren't interested in this event, skip it immediately ... */39 if (event != FB_EVENT_BLANK)40 return 0;41 42 blank = fb_event->data;43 new_status = *blank ? BLANK : UNBLANK;44 45 if (new_status == n->old_status)46 return 0;47 48 if ((n->old_status == UNBLANK) ^ n->invert) {49 n->brightness = led->brightness;50 led_set_brightness_nosleep(led, LED_OFF);51 } else {52 led_set_brightness_nosleep(led, n->brightness);53 }54 55 n->old_status = new_status;56 57 return 0;58}59 60static ssize_t bl_trig_invert_show(struct device *dev,61 struct device_attribute *attr, char *buf)62{63 struct bl_trig_notifier *n = led_trigger_get_drvdata(dev);64 65 return sprintf(buf, "%u\n", n->invert);66}67 68static ssize_t bl_trig_invert_store(struct device *dev,69 struct device_attribute *attr, const char *buf, size_t num)70{71 struct led_classdev *led = led_trigger_get_led(dev);72 struct bl_trig_notifier *n = led_trigger_get_drvdata(dev);73 unsigned long invert;74 int ret;75 76 ret = kstrtoul(buf, 10, &invert);77 if (ret < 0)78 return ret;79 80 if (invert > 1)81 return -EINVAL;82 83 n->invert = invert;84 85 /* After inverting, we need to update the LED. */86 if ((n->old_status == BLANK) ^ n->invert)87 led_set_brightness_nosleep(led, LED_OFF);88 else89 led_set_brightness_nosleep(led, n->brightness);90 91 return num;92}93static DEVICE_ATTR(inverted, 0644, bl_trig_invert_show, bl_trig_invert_store);94 95static struct attribute *bl_trig_attrs[] = {96 &dev_attr_inverted.attr,97 NULL,98};99ATTRIBUTE_GROUPS(bl_trig);100 101static int bl_trig_activate(struct led_classdev *led)102{103 int ret;104 105 struct bl_trig_notifier *n;106 107 n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);108 if (!n)109 return -ENOMEM;110 led_set_trigger_data(led, n);111 112 n->led = led;113 n->brightness = led->brightness;114 n->old_status = UNBLANK;115 n->notifier.notifier_call = fb_notifier_callback;116 117 ret = fb_register_client(&n->notifier);118 if (ret)119 dev_err(led->dev, "unable to register backlight trigger\n");120 121 return 0;122}123 124static void bl_trig_deactivate(struct led_classdev *led)125{126 struct bl_trig_notifier *n = led_get_trigger_data(led);127 128 fb_unregister_client(&n->notifier);129 kfree(n);130}131 132static struct led_trigger bl_led_trigger = {133 .name = "backlight",134 .activate = bl_trig_activate,135 .deactivate = bl_trig_deactivate,136 .groups = bl_trig_groups,137};138module_led_trigger(bl_led_trigger);139 140MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");141MODULE_DESCRIPTION("Backlight emulation LED trigger");142MODULE_LICENSE("GPL v2");143