drivers/input/misc/pwm-beeper.c

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