drivers/leds/trigger/ledtrig-actpwr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Activity/power trigger
   4  *
   5  * Copyright (C) 2020 Raspberry Pi (Trading) Ltd.
   6  *
   7  * Based on Atsushi Nemoto's ledtrig-heartbeat.c, although there may be
   8  * nothing left of the original now.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/timer.h>
  15 #include <linux/leds.h>
  16 #include "../leds.h"
  17
  18 enum {
  19         TRIG_ACT,
  20         TRIG_PWR,
  21
  22         TRIG_COUNT
  23 };
  24
  25 struct actpwr_trig_src {
  26         const char *name;
  27         int interval;
  28         bool invert;
  29 };
  30
  31 struct actpwr_vled {
  32         struct led_classdev cdev;
  33         struct actpwr_trig_data *parent;
  34         enum led_brightness value;
  35         unsigned int interval;
  36         bool invert;
  37 };
  38
  39 struct actpwr_trig_data {
  40         struct led_trigger trig;
  41         struct actpwr_vled virt_leds[TRIG_COUNT];
  42         struct actpwr_vled *active;
  43         struct timer_list timer;
  44         int next_active;
  45 };
  46
  47 static int actpwr_trig_activate(struct led_classdev *led_cdev);
  48 static void actpwr_trig_deactivate(struct led_classdev *led_cdev);
  49
  50 static const struct actpwr_trig_src actpwr_trig_sources[TRIG_COUNT] = {
  51         [TRIG_ACT] = { "mmc0", 500, true },
  52         [TRIG_PWR] = { "default-on", 500, false },
  53 };
  54
  55 static struct actpwr_trig_data actpwr_data = {
  56         {
  57                 .name     = "actpwr",
  58                 .activate = actpwr_trig_activate,
  59                 .deactivate = actpwr_trig_deactivate,
  60         }
  61 };
  62
  63 static void actpwr_brightness_set(struct led_classdev *led_cdev,
  64                                   enum led_brightness value)
  65 {
  66         struct actpwr_vled *vled = container_of(led_cdev, struct actpwr_vled,
  67                                                cdev);
  68         struct actpwr_trig_data *trig = vled->parent;
  69
  70         if (vled->invert)
  71                 value = !value;
  72         vled->value = value;
  73
  74         if (vled == trig->active)
  75                 led_trigger_event(&trig->trig, value);
  76 }
  77
  78 static int actpwr_brightness_set_blocking(struct led_classdev *led_cdev,
  79                                           enum led_brightness value)
  80 {
  81         actpwr_brightness_set(led_cdev, value);
  82         return 0;
  83 }
  84
  85 static enum led_brightness actpwr_brightness_get(struct led_classdev *led_cdev)
  86 {
  87         struct actpwr_vled *vled = container_of(led_cdev, struct actpwr_vled,
  88                                               cdev);
  89
  90         return vled->value;
  91 }
  92
  93 static void actpwr_trig_cycle(struct timer_list *t)
  94 {
  95         struct actpwr_trig_data *trig  = &actpwr_data;
  96         struct actpwr_vled *active;
  97
  98         active = &trig->virt_leds[trig->next_active];
  99         trig->active = active;
 100         trig->next_active = (trig->next_active + 1) % TRIG_COUNT;
 101
 102         led_trigger_event(&trig->trig, active->value);
 103
 104         mod_timer(&trig->timer, jiffies + msecs_to_jiffies(active->interval));
 105 }
 106
 107 static int actpwr_trig_activate(struct led_classdev *led_cdev)
 108 {
 109         struct actpwr_trig_data *trig  = &actpwr_data;
 110
 111         /* Start the timer if this is the first LED */
 112         if (!trig->active)
 113                 actpwr_trig_cycle(&trig->timer);
 114         else
 115                 led_set_brightness_nosleep(led_cdev, trig->active->value);
 116
 117         return 0;
 118 }
 119
 120 static void actpwr_trig_deactivate(struct led_classdev *led_cdev)
 121 {
 122         struct actpwr_trig_data *trig  = &actpwr_data;
 123
 124         if (list_empty(&trig->trig.led_cdevs)) {
 125                 del_timer_sync(&trig->timer);
 126                 trig->active = NULL;
 127         }
 128 }
 129
 130 static int __init actpwr_trig_init(void)
 131 {
 132         struct actpwr_trig_data *trig  = &actpwr_data;
 133         int ret = 0;
 134         int i;
 135
 136         timer_setup(&trig->timer, actpwr_trig_cycle, 0);
 137
 138         /* Register one "LED" for each source trigger */
 139         for (i = 0; i < TRIG_COUNT; i++)
 140         {
 141                 struct actpwr_vled *vled = &trig->virt_leds[i];
 142                 struct led_classdev *cdev = &vled->cdev;
 143                 const struct actpwr_trig_src *src = &actpwr_trig_sources[i];
 144
 145                 vled->parent = trig;
 146                 vled->interval = src->interval;
 147                 vled->invert = src->invert;
 148                 cdev->name = src->name;
 149                 cdev->brightness_set = actpwr_brightness_set;
 150                 cdev->brightness_set_blocking = actpwr_brightness_set_blocking;
 151                 cdev->brightness_get = actpwr_brightness_get;
 152                 cdev->default_trigger = src->name;
 153                 ret = led_classdev_register(NULL, cdev);
 154                 if (ret)
 155                         goto error_classdev;
 156         }
 157
 158         ret = led_trigger_register(&trig->trig);
 159         if (ret)
 160                 goto error_classdev;
 161
 162         return 0;
 163
 164 error_classdev:
 165         while (i > 0)
 166         {
 167                 i--;
 168                 led_classdev_unregister(&trig->virt_leds[i].cdev);
 169         }
 170
 171         return ret;
 172 }
 173
 174 static void __exit actpwr_trig_exit(void)
 175 {
 176         int i;
 177
 178         led_trigger_unregister(&actpwr_data.trig);
 179         for (i = 0; i < TRIG_COUNT; i++)
 180         {
 181                 led_classdev_unregister(&actpwr_data.virt_leds[i].cdev);
 182         }
 183 }
 184
 185 module_init(actpwr_trig_init);
 186 module_exit(actpwr_trig_exit);
 187
 188 MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.com>");
 189 MODULE_DESCRIPTION("ACT/PWR LED trigger");
 190 MODULE_LICENSE("GPL v2");