drivers/input/misc/pwm-beeper.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
   4  *  PWM beeper driver
   5  */
   6
   7 #include <linux/input.h>
   8 #include <linux/regulator/consumer.h>
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/property.h>
  14 #include <linux/pwm.h>
  15 #include <linux/slab.h>
  16 #include <linux/workqueue.h>
  17
  18 struct pwm_beeper {
  19         struct input_dev *input;
  20         struct pwm_device *pwm;
  21         struct regulator *amplifier;
  22         struct work_struct work;
  23         unsigned long period;
  24         unsigned int bell_frequency;
  25         bool suspended;
  26         bool amplifier_on;
  27 };
  28
  29 #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
  30
  31 static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
  32 {
  33         struct pwm_state state;
  34         int error;
  35
  36         pwm_get_state(beeper->pwm, &state);
  37
  38         state.enabled = true;
  39         state.period = period;
  40         pwm_set_relative_duty_cycle(&state, 50, 100);
  41
  42         error = pwm_apply_state(beeper->pwm, &state);
  43         if (error)
  44                 return error;
  45
  46         if (!beeper->amplifier_on) {
  47                 error = regulator_enable(beeper->amplifier);
  48                 if (error) {
  49                         pwm_disable(beeper->pwm);
  50                         return error;
  51                 }
  52
  53                 beeper->amplifier_on = true;
  54         }
  55
  56         return 0;
  57 }
  58
  59 static void pwm_beeper_off(struct pwm_beeper *beeper)
  60 {
  61         if (beeper->amplifier_on) {
  62                 regulator_disable(beeper->amplifier);
  63                 beeper->amplifier_on = false;
  64         }
  65
  66         pwm_disable(beeper->pwm);
  67 }
  68
  69 static void pwm_beeper_work(struct work_struct *work)
  70 {
  71         struct pwm_beeper *beeper = container_of(work, struct pwm_beeper, work);
  72         unsigned long period = READ_ONCE(beeper->period);
  73
  74         if (period)
  75                 pwm_beeper_on(beeper, period);
  76         else
  77                 pwm_beeper_off(beeper);
  78 }
  79
  80 static int pwm_beeper_event(struct input_dev *input,
  81                             unsigned int type, unsigned int code, int value)
  82 {
  83         struct pwm_beeper *beeper = input_get_drvdata(input);
  84
  85         if (type != EV_SND || value < 0)
  86                 return -EINVAL;
  87
  88         switch (code) {
  89         case SND_BELL:
  90                 value = value ? beeper->bell_frequency : 0;
  91                 break;
  92         case SND_TONE:
  93                 break;
  94         default:
  95                 return -EINVAL;
  96         }
  97
  98         if (value == 0)
  99                 beeper->period = 0;
 100         else
 101                 beeper->period = HZ_TO_NANOSECONDS(value);
 102
 103         if (!beeper->suspended)
 104                 schedule_work(&beeper->work);
 105
 106         return 0;
 107 }
 108
 109 static void pwm_beeper_stop(struct pwm_beeper *beeper)
 110 {
 111         cancel_work_sync(&beeper->work);
 112         pwm_beeper_off(beeper);
 113 }
 114
 115 static void pwm_beeper_close(struct input_dev *input)
 116 {
 117         struct pwm_beeper *beeper = input_get_drvdata(input);
 118
 119         pwm_beeper_stop(beeper);
 120 }
 121
 122 static int pwm_beeper_probe(struct platform_device *pdev)
 123 {
 124         struct device *dev = &pdev->dev;
 125         struct pwm_beeper *beeper;
 126         struct pwm_state state;
 127         u32 bell_frequency;
 128         int error;
 129
 130         beeper = devm_kzalloc(dev, sizeof(*beeper), GFP_KERNEL);
 131         if (!beeper)
 132                 return -ENOMEM;
 133
 134         beeper->pwm = devm_pwm_get(dev, NULL);
 135         if (IS_ERR(beeper->pwm)) {
 136                 error = PTR_ERR(beeper->pwm);
 137                 if (error != -EPROBE_DEFER)
 138                         dev_err(dev, "Failed to request PWM device: %d\n",
 139                                 error);
 140                 return error;
 141         }
 142
 143         /* Sync up PWM state and ensure it is off. */
 144         pwm_init_state(beeper->pwm, &state);
 145         state.enabled = false;
 146         error = pwm_apply_state(beeper->pwm, &state);
 147         if (error) {
 148                 dev_err(dev, "failed to apply initial PWM state: %d\n",
 149                         error);
 150                 return error;
 151         }
 152
 153         beeper->amplifier = devm_regulator_get(dev, "amp");
 154         if (IS_ERR(beeper->amplifier)) {
 155                 error = PTR_ERR(beeper->amplifier);
 156                 if (error != -EPROBE_DEFER)
 157                         dev_err(dev, "Failed to get 'amp' regulator: %d\n",
 158                                 error);
 159                 return error;
 160         }
 161
 162         INIT_WORK(&beeper->work, pwm_beeper_work);
 163
 164         error = device_property_read_u32(dev, "beeper-hz", &bell_frequency);
 165         if (error) {
 166                 bell_frequency = 1000;
 167                 dev_dbg(dev,
 168                         "failed to parse 'beeper-hz' property, using default: %uHz\n",
 169                         bell_frequency);
 170         }
 171
 172         beeper->bell_frequency = bell_frequency;
 173
 174         beeper->input = devm_input_allocate_device(dev);
 175         if (!beeper->input) {
 176                 dev_err(dev, "Failed to allocate input device\n");
 177                 return -ENOMEM;
 178         }
 179
 180         beeper->input->name = "pwm-beeper";
 181         beeper->input->phys = "pwm/input0";
 182         beeper->input->id.bustype = BUS_HOST;
 183         beeper->input->id.vendor = 0x001f;
 184         beeper->input->id.product = 0x0001;
 185         beeper->input->id.version = 0x0100;
 186
 187         input_set_capability(beeper->input, EV_SND, SND_TONE);
 188         input_set_capability(beeper->input, EV_SND, SND_BELL);
 189
 190         beeper->input->event = pwm_beeper_event;
 191         beeper->input->close = pwm_beeper_close;
 192
 193         input_set_drvdata(beeper->input, beeper);
 194
 195         error = input_register_device(beeper->input);
 196         if (error) {
 197                 dev_err(dev, "Failed to register input device: %d\n", error);
 198                 return error;
 199         }
 200
 201         platform_set_drvdata(pdev, beeper);
 202
 203         return 0;
 204 }
 205
 206 static int __maybe_unused pwm_beeper_suspend(struct device *dev)
 207 {
 208         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 209
 210         /*
 211          * Spinlock is taken here is not to protect write to
 212          * beeper->suspended, but to ensure that pwm_beeper_event
 213          * does not re-submit work once flag is set.
 214          */
 215         spin_lock_irq(&beeper->input->event_lock);
 216         beeper->suspended = true;
 217         spin_unlock_irq(&beeper->input->event_lock);
 218
 219         pwm_beeper_stop(beeper);
 220
 221         return 0;
 222 }
 223
 224 static int __maybe_unused pwm_beeper_resume(struct device *dev)
 225 {
 226         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 227
 228         spin_lock_irq(&beeper->input->event_lock);
 229         beeper->suspended = false;
 230         spin_unlock_irq(&beeper->input->event_lock);
 231
 232         /* Let worker figure out if we should resume beeping */
 233         schedule_work(&beeper->work);
 234
 235         return 0;
 236 }
 237
 238 static SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
 239                          pwm_beeper_suspend, pwm_beeper_resume);
 240
 241 #ifdef CONFIG_OF
 242 static const struct of_device_id pwm_beeper_match[] = {
 243         { .compatible = "pwm-beeper", },
 244         { },
 245 };
 246 MODULE_DEVICE_TABLE(of, pwm_beeper_match);
 247 #endif
 248
 249 static struct platform_driver pwm_beeper_driver = {
 250         .probe  = pwm_beeper_probe,
 251         .driver = {
 252                 .name   = "pwm-beeper",
 253                 .pm     = &pwm_beeper_pm_ops,
 254                 .of_match_table = of_match_ptr(pwm_beeper_match),
 255         },
 256 };
 257 module_platform_driver(pwm_beeper_driver);
 258
 259 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 260 MODULE_DESCRIPTION("PWM beeper driver");
 261 MODULE_LICENSE("GPL");
 262 MODULE_ALIAS("platform:pwm-beeper");