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_might_sleep(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                 return dev_err_probe(dev, PTR_ERR(beeper->pwm), "Failed to request PWM device\n");
 137
 138         /* Sync up PWM state and ensure it is off. */
 139         pwm_init_state(beeper->pwm, &state);
 140         state.enabled = false;
 141         error = pwm_apply_might_sleep(beeper->pwm, &state);
 142         if (error) {
 143                 dev_err(dev, "failed to apply initial PWM state: %d\n",
 144                         error);
 145                 return error;
 146         }
 147
 148         beeper->amplifier = devm_regulator_get(dev, "amp");
 149         if (IS_ERR(beeper->amplifier))
 150                 return dev_err_probe(dev, PTR_ERR(beeper->amplifier),
 151                                      "Failed to get 'amp' regulator\n");
 152
 153         INIT_WORK(&beeper->work, pwm_beeper_work);
 154
 155         error = device_property_read_u32(dev, "beeper-hz", &bell_frequency);
 156         if (error) {
 157                 bell_frequency = 1000;
 158                 dev_dbg(dev,
 159                         "failed to parse 'beeper-hz' property, using default: %uHz\n",
 160                         bell_frequency);
 161         }
 162
 163         beeper->bell_frequency = bell_frequency;
 164
 165         beeper->input = devm_input_allocate_device(dev);
 166         if (!beeper->input) {
 167                 dev_err(dev, "Failed to allocate input device\n");
 168                 return -ENOMEM;
 169         }
 170
 171         beeper->input->name = "pwm-beeper";
 172         beeper->input->phys = "pwm/input0";
 173         beeper->input->id.bustype = BUS_HOST;
 174         beeper->input->id.vendor = 0x001f;
 175         beeper->input->id.product = 0x0001;
 176         beeper->input->id.version = 0x0100;
 177
 178         input_set_capability(beeper->input, EV_SND, SND_TONE);
 179         input_set_capability(beeper->input, EV_SND, SND_BELL);
 180
 181         beeper->input->event = pwm_beeper_event;
 182         beeper->input->close = pwm_beeper_close;
 183
 184         input_set_drvdata(beeper->input, beeper);
 185
 186         error = input_register_device(beeper->input);
 187         if (error) {
 188                 dev_err(dev, "Failed to register input device: %d\n", error);
 189                 return error;
 190         }
 191
 192         platform_set_drvdata(pdev, beeper);
 193
 194         return 0;
 195 }
 196
 197 static int pwm_beeper_suspend(struct device *dev)
 198 {
 199         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 200
 201         /*
 202          * Spinlock is taken here is not to protect write to
 203          * beeper->suspended, but to ensure that pwm_beeper_event
 204          * does not re-submit work once flag is set.
 205          */
 206         scoped_guard(spinlock_irq, &beeper->input->event_lock) {
 207                 beeper->suspended = true;
 208         }
 209
 210         pwm_beeper_stop(beeper);
 211
 212         return 0;
 213 }
 214
 215 static int pwm_beeper_resume(struct device *dev)
 216 {
 217         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 218
 219         scoped_guard(spinlock_irq, &beeper->input->event_lock) {
 220                 beeper->suspended = false;
 221         }
 222
 223         /* Let worker figure out if we should resume beeping */
 224         schedule_work(&beeper->work);
 225
 226         return 0;
 227 }
 228
 229 static DEFINE_SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
 230                                 pwm_beeper_suspend, pwm_beeper_resume);
 231
 232 #ifdef CONFIG_OF
 233 static const struct of_device_id pwm_beeper_match[] = {
 234         { .compatible = "pwm-beeper", },
 235         { },
 236 };
 237 MODULE_DEVICE_TABLE(of, pwm_beeper_match);
 238 #endif
 239
 240 static struct platform_driver pwm_beeper_driver = {
 241         .probe  = pwm_beeper_probe,
 242         .driver = {
 243                 .name   = "pwm-beeper",
 244                 .pm     = pm_sleep_ptr(&pwm_beeper_pm_ops),
 245                 .of_match_table = of_match_ptr(pwm_beeper_match),
 246         },
 247 };
 248 module_platform_driver(pwm_beeper_driver);
 249
 250 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 251 MODULE_DESCRIPTION("PWM beeper driver");
 252 MODULE_LICENSE("GPL");
 253 MODULE_ALIAS("platform:pwm-beeper");