drivers/input/misc/pwm-beeper.c

   1 /*
   2  *  Copyright (C) 2010, Lars-Peter Clausen <[email protected]>
   3  *  PWM beeper driver
   4  *
   5  *  This program is free software; you can redistribute it and/or modify it
   6  *  under  the terms of the GNU General  Public License as published by the
   7  *  Free Software Foundation;  either version 2 of the License, or (at your
   8  *  option) any later version.
   9  *
  10  *  You should have received a copy of the GNU General Public License along
  11  *  with this program; if not, write to the Free Software Foundation, Inc.,
  12  *  675 Mass Ave, Cambridge, MA 02139, USA.
  13  *
  14  */
  15
  16 #include <linux/input.h>
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/pwm.h>
  22 #include <linux/slab.h>
  23 #include <linux/workqueue.h>
  24
  25 struct pwm_beeper {
  26         struct input_dev *input;
  27         struct pwm_device *pwm;
  28         struct work_struct work;
  29         unsigned long period;
  30         bool suspended;
  31 };
  32
  33 #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
  34
  35 static void __pwm_beeper_set(struct pwm_beeper *beeper)
  36 {
  37         unsigned long period = beeper->period;
  38
  39         if (period) {
  40                 pwm_config(beeper->pwm, period / 2, period);
  41                 pwm_enable(beeper->pwm);
  42         } else
  43                 pwm_disable(beeper->pwm);
  44 }
  45
  46 static void pwm_beeper_work(struct work_struct *work)
  47 {
  48         struct pwm_beeper *beeper =
  49                 container_of(work, struct pwm_beeper, work);
  50
  51         __pwm_beeper_set(beeper);
  52 }
  53
  54 static int pwm_beeper_event(struct input_dev *input,
  55                             unsigned int type, unsigned int code, int value)
  56 {
  57         struct pwm_beeper *beeper = input_get_drvdata(input);
  58
  59         if (type != EV_SND || value < 0)
  60                 return -EINVAL;
  61
  62         switch (code) {
  63         case SND_BELL:
  64                 value = value ? 1000 : 0;
  65                 break;
  66         case SND_TONE:
  67                 break;
  68         default:
  69                 return -EINVAL;
  70         }
  71
  72         if (value == 0)
  73                 beeper->period = 0;
  74         else
  75                 beeper->period = HZ_TO_NANOSECONDS(value);
  76
  77         if (!beeper->suspended)
  78                 schedule_work(&beeper->work);
  79
  80         return 0;
  81 }
  82
  83 static void pwm_beeper_stop(struct pwm_beeper *beeper)
  84 {
  85         cancel_work_sync(&beeper->work);
  86
  87         if (beeper->period)
  88                 pwm_disable(beeper->pwm);
  89 }
  90
  91 static void pwm_beeper_close(struct input_dev *input)
  92 {
  93         struct pwm_beeper *beeper = input_get_drvdata(input);
  94
  95         pwm_beeper_stop(beeper);
  96 }
  97
  98 static int pwm_beeper_probe(struct platform_device *pdev)
  99 {
 100         struct device *dev = &pdev->dev;
 101         struct pwm_beeper *beeper;
 102         int error;
 103
 104         beeper = devm_kzalloc(dev, sizeof(*beeper), GFP_KERNEL);
 105         if (!beeper)
 106                 return -ENOMEM;
 107
 108         beeper->pwm = devm_pwm_get(dev, NULL);
 109         if (IS_ERR(beeper->pwm)) {
 110                 error = PTR_ERR(beeper->pwm);
 111                 dev_err(dev, "Failed to request PWM device: %d\n", error);
 112                 return error;
 113         }
 114
 115         /*
 116          * FIXME: pwm_apply_args() should be removed when switching to
 117          * the atomic PWM API.
 118          */
 119         pwm_apply_args(beeper->pwm);
 120
 121         INIT_WORK(&beeper->work, pwm_beeper_work);
 122
 123         beeper->input = devm_input_allocate_device(dev);
 124         if (!beeper->input) {
 125                 dev_err(dev, "Failed to allocate input device\n");
 126                 return -ENOMEM;
 127         }
 128
 129         beeper->input->name = "pwm-beeper";
 130         beeper->input->phys = "pwm/input0";
 131         beeper->input->id.bustype = BUS_HOST;
 132         beeper->input->id.vendor = 0x001f;
 133         beeper->input->id.product = 0x0001;
 134         beeper->input->id.version = 0x0100;
 135
 136         input_set_capability(beeper->input, EV_SND, SND_TONE);
 137         input_set_capability(beeper->input, EV_SND, SND_BELL);
 138
 139         beeper->input->event = pwm_beeper_event;
 140         beeper->input->close = pwm_beeper_close;
 141
 142         input_set_drvdata(beeper->input, beeper);
 143
 144         error = input_register_device(beeper->input);
 145         if (error) {
 146                 dev_err(dev, "Failed to register input device: %d\n", error);
 147                 return error;
 148         }
 149
 150         platform_set_drvdata(pdev, beeper);
 151
 152         return 0;
 153 }
 154
 155 static int __maybe_unused pwm_beeper_suspend(struct device *dev)
 156 {
 157         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 158
 159         /*
 160          * Spinlock is taken here is not to protect write to
 161          * beeper->suspended, but to ensure that pwm_beeper_event
 162          * does not re-submit work once flag is set.
 163          */
 164         spin_lock_irq(&beeper->input->event_lock);
 165         beeper->suspended = true;
 166         spin_unlock_irq(&beeper->input->event_lock);
 167
 168         pwm_beeper_stop(beeper);
 169
 170         return 0;
 171 }
 172
 173 static int __maybe_unused pwm_beeper_resume(struct device *dev)
 174 {
 175         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 176
 177         spin_lock_irq(&beeper->input->event_lock);
 178         beeper->suspended = false;
 179         spin_unlock_irq(&beeper->input->event_lock);
 180
 181         /* Let worker figure out if we should resume beeping */
 182         schedule_work(&beeper->work);
 183
 184         return 0;
 185 }
 186
 187 static SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
 188                          pwm_beeper_suspend, pwm_beeper_resume);
 189
 190 #ifdef CONFIG_OF
 191 static const struct of_device_id pwm_beeper_match[] = {
 192         { .compatible = "pwm-beeper", },
 193         { },
 194 };
 195 MODULE_DEVICE_TABLE(of, pwm_beeper_match);
 196 #endif
 197
 198 static struct platform_driver pwm_beeper_driver = {
 199         .probe  = pwm_beeper_probe,
 200         .driver = {
 201                 .name   = "pwm-beeper",
 202                 .pm     = &pwm_beeper_pm_ops,
 203                 .of_match_table = of_match_ptr(pwm_beeper_match),
 204         },
 205 };
 206 module_platform_driver(pwm_beeper_driver);
 207
 208 MODULE_AUTHOR("Lars-Peter Clausen <[email protected]>");
 209 MODULE_DESCRIPTION("PWM beeper driver");
 210 MODULE_LICENSE("GPL");
 211 MODULE_ALIAS("platform:pwm-beeper");