cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ledtrig-backlight.c (3268B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Backlight emulation LED trigger
      4 *
      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		1
     18#define UNBLANK		0
     19
     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	else
     89		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");