199 lines · c
1// SPDX-License-Identifier: GPL-2.02//3// LED Kernel Transient Trigger4//5// Transient trigger allows one shot timer activation. Please refer to6// Documentation/leds/ledtrig-transient.rst for details7// Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>8//9// Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's10// ledtrig-heartbeat.c11// Design and use-case input from Jonas Bonn <jonas@southpole.se> and12// Neil Brown <neilb@suse.de>13 14#include <linux/module.h>15#include <linux/kernel.h>16#include <linux/init.h>17#include <linux/device.h>18#include <linux/slab.h>19#include <linux/timer.h>20#include <linux/leds.h>21#include "../leds.h"22 23struct transient_trig_data {24 int activate;25 int state;26 int restore_state;27 unsigned long duration;28 struct timer_list timer;29 struct led_classdev *led_cdev;30};31 32static void transient_timer_function(struct timer_list *t)33{34 struct transient_trig_data *transient_data =35 from_timer(transient_data, t, timer);36 struct led_classdev *led_cdev = transient_data->led_cdev;37 38 transient_data->activate = 0;39 led_set_brightness_nosleep(led_cdev, transient_data->restore_state);40}41 42static ssize_t transient_activate_show(struct device *dev,43 struct device_attribute *attr, char *buf)44{45 struct transient_trig_data *transient_data =46 led_trigger_get_drvdata(dev);47 48 return sprintf(buf, "%d\n", transient_data->activate);49}50 51static ssize_t transient_activate_store(struct device *dev,52 struct device_attribute *attr, const char *buf, size_t size)53{54 struct led_classdev *led_cdev = led_trigger_get_led(dev);55 struct transient_trig_data *transient_data =56 led_trigger_get_drvdata(dev);57 unsigned long state;58 ssize_t ret;59 60 ret = kstrtoul(buf, 10, &state);61 if (ret)62 return ret;63 64 if (state != 1 && state != 0)65 return -EINVAL;66 67 /* cancel the running timer */68 if (state == 0 && transient_data->activate == 1) {69 del_timer(&transient_data->timer);70 transient_data->activate = state;71 led_set_brightness_nosleep(led_cdev,72 transient_data->restore_state);73 return size;74 }75 76 /* start timer if there is no active timer */77 if (state == 1 && transient_data->activate == 0 &&78 transient_data->duration != 0) {79 transient_data->activate = state;80 led_set_brightness_nosleep(led_cdev, transient_data->state);81 transient_data->restore_state =82 (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;83 mod_timer(&transient_data->timer,84 jiffies + msecs_to_jiffies(transient_data->duration));85 }86 87 /* state == 0 && transient_data->activate == 088 timer is not active - just return */89 /* state == 1 && transient_data->activate == 190 timer is already active - just return */91 92 return size;93}94 95static ssize_t transient_duration_show(struct device *dev,96 struct device_attribute *attr, char *buf)97{98 struct transient_trig_data *transient_data = led_trigger_get_drvdata(dev);99 100 return sprintf(buf, "%lu\n", transient_data->duration);101}102 103static ssize_t transient_duration_store(struct device *dev,104 struct device_attribute *attr, const char *buf, size_t size)105{106 struct transient_trig_data *transient_data =107 led_trigger_get_drvdata(dev);108 unsigned long state;109 ssize_t ret;110 111 ret = kstrtoul(buf, 10, &state);112 if (ret)113 return ret;114 115 transient_data->duration = state;116 return size;117}118 119static ssize_t transient_state_show(struct device *dev,120 struct device_attribute *attr, char *buf)121{122 struct transient_trig_data *transient_data =123 led_trigger_get_drvdata(dev);124 int state;125 126 state = (transient_data->state == LED_FULL) ? 1 : 0;127 return sprintf(buf, "%d\n", state);128}129 130static ssize_t transient_state_store(struct device *dev,131 struct device_attribute *attr, const char *buf, size_t size)132{133 struct transient_trig_data *transient_data =134 led_trigger_get_drvdata(dev);135 unsigned long state;136 ssize_t ret;137 138 ret = kstrtoul(buf, 10, &state);139 if (ret)140 return ret;141 142 if (state != 1 && state != 0)143 return -EINVAL;144 145 transient_data->state = (state == 1) ? LED_FULL : LED_OFF;146 return size;147}148 149static DEVICE_ATTR(activate, 0644, transient_activate_show,150 transient_activate_store);151static DEVICE_ATTR(duration, 0644, transient_duration_show,152 transient_duration_store);153static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);154 155static struct attribute *transient_trig_attrs[] = {156 &dev_attr_activate.attr,157 &dev_attr_duration.attr,158 &dev_attr_state.attr,159 NULL160};161ATTRIBUTE_GROUPS(transient_trig);162 163static int transient_trig_activate(struct led_classdev *led_cdev)164{165 struct transient_trig_data *tdata;166 167 tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);168 if (!tdata)169 return -ENOMEM;170 171 led_set_trigger_data(led_cdev, tdata);172 tdata->led_cdev = led_cdev;173 174 timer_setup(&tdata->timer, transient_timer_function, 0);175 176 return 0;177}178 179static void transient_trig_deactivate(struct led_classdev *led_cdev)180{181 struct transient_trig_data *transient_data = led_get_trigger_data(led_cdev);182 183 timer_shutdown_sync(&transient_data->timer);184 led_set_brightness_nosleep(led_cdev, transient_data->restore_state);185 kfree(transient_data);186}187 188static struct led_trigger transient_trigger = {189 .name = "transient",190 .activate = transient_trig_activate,191 .deactivate = transient_trig_deactivate,192 .groups = transient_trig_groups,193};194module_led_trigger(transient_trigger);195 196MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");197MODULE_DESCRIPTION("Transient LED trigger");198MODULE_LICENSE("GPL v2");199