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/property.h>
  23 #include <linux/pwm.h>
  24 #include <linux/slab.h>
  25 #include <linux/workqueue.h>
  26
  27 struct pwm_beeper {
  28         struct input_dev *input;
  29         struct pwm_device *pwm;
  30         struct regulator *amplifier;
  31         struct work_struct work;
  32         unsigned long period;
  33         unsigned int bell_frequency;
  34         bool suspended;
  35         bool amplifier_on;
  36 };
  37
  38 #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
  39
  40 static int pwm_beeper_on(struct pwm_beeper *beeper, unsigned long period)
  41 {
  42         struct pwm_state state;
  43         int error;
  44
  45         pwm_get_state(beeper->pwm, &state);
  46
  47         state.enabled = true;
  48         state.period = period;
  49         pwm_set_relative_duty_cycle(&state, 50, 100);
  50
  51         error = pwm_apply_state(beeper->pwm, &state);
  52         if (error)
  53                 return error;
  54
  55         if (!beeper->amplifier_on) {
  56                 error = regulator_enable(beeper->amplifier);
  57                 if (error) {
  58                         pwm_disable(beeper->pwm);
  59                         return error;
  60                 }
  61
  62                 beeper->amplifier_on = true;
  63         }
  64
  65         return 0;
  66 }
  67
  68 static void pwm_beeper_off(struct pwm_beeper *beeper)
  69 {
  70         if (beeper->amplifier_on) {
  71                 regulator_disable(beeper->amplifier);
  72                 beeper->amplifier_on = false;
  73         }
  74
  75         pwm_disable(beeper->pwm);
  76 }
  77
  78 static void pwm_beeper_work(struct work_struct *work)
  79 {
  80         struct pwm_beeper *beeper = container_of(work, struct pwm_beeper, work);
  81         unsigned long period = READ_ONCE(beeper->period);
  82
  83         if (period)
  84                 pwm_beeper_on(beeper, period);
  85         else
  86                 pwm_beeper_off(beeper);
  87 }
  88
  89 static int pwm_beeper_event(struct input_dev *input,
  90                             unsigned int type, unsigned int code, int value)
  91 {
  92         struct pwm_beeper *beeper = input_get_drvdata(input);
  93
  94         if (type != EV_SND || value < 0)
  95                 return -EINVAL;
  96
  97         switch (code) {
  98         case SND_BELL:
  99                 value = value ? beeper->bell_frequency : 0;
 100                 break;
 101         case SND_TONE:
 102                 break;
 103         default:
 104                 return -EINVAL;
 105         }
 106
 107         if (value == 0)
 108                 beeper->period = 0;
 109         else
 110                 beeper->period = HZ_TO_NANOSECONDS(value);
 111
 112         if (!beeper->suspended)
 113                 schedule_work(&beeper->work);
 114
 115         return 0;
 116 }
 117
 118 static void pwm_beeper_stop(struct pwm_beeper *beeper)
 119 {
 120         cancel_work_sync(&beeper->work);
 121         pwm_beeper_off(beeper);
 122 }
 123
 124 static void pwm_beeper_close(struct input_dev *input)
 125 {
 126         struct pwm_beeper *beeper = input_get_drvdata(input);
 127
 128         pwm_beeper_stop(beeper);
 129 }
 130
 131 static int pwm_beeper_probe(struct platform_device *pdev)
 132 {
 133         struct device *dev = &pdev->dev;
 134         struct pwm_beeper *beeper;
 135         struct pwm_state state;
 136         u32 bell_frequency;
 137         int error;
 138
 139         beeper = devm_kzalloc(dev, sizeof(*beeper), GFP_KERNEL);
 140         if (!beeper)
 141                 return -ENOMEM;
 142
 143         beeper->pwm = devm_pwm_get(dev, NULL);
 144         if (IS_ERR(beeper->pwm)) {
 145                 error = PTR_ERR(beeper->pwm);
 146                 if (error != -EPROBE_DEFER)
 147                         dev_err(dev, "Failed to request PWM device: %d\n",
 148                                 error);
 149                 return error;
 150         }
 151
 152         /* Sync up PWM state and ensure it is off. */
 153         pwm_init_state(beeper->pwm, &state);
 154         state.enabled = false;
 155         error = pwm_apply_state(beeper->pwm, &state);
 156         if (error) {
 157                 dev_err(dev, "failed to apply initial PWM state: %d\n",
 158                         error);
 159                 return error;
 160         }
 161
 162         beeper->amplifier = devm_regulator_get(dev, "amp");
 163         if (IS_ERR(beeper->amplifier)) {
 164                 error = PTR_ERR(beeper->amplifier);
 165                 if (error != -EPROBE_DEFER)
 166                         dev_err(dev, "Failed to get 'amp' regulator: %d\n",
 167                                 error);
 168                 return error;
 169         }
 170
 171         INIT_WORK(&beeper->work, pwm_beeper_work);
 172
 173         error = device_property_read_u32(dev, "beeper-hz", &bell_frequency);
 174         if (error) {
 175                 bell_frequency = 1000;
 176                 dev_dbg(dev,
 177                         "failed to parse 'beeper-hz' property, using default: %uHz\n",
 178                         bell_frequency);
 179         }
 180
 181         beeper->bell_frequency = bell_frequency;
 182
 183         beeper->input = devm_input_allocate_device(dev);
 184         if (!beeper->input) {
 185                 dev_err(dev, "Failed to allocate input device\n");
 186                 return -ENOMEM;
 187         }
 188
 189         beeper->input->name = "pwm-beeper";
 190         beeper->input->phys = "pwm/input0";
 191         beeper->input->id.bustype = BUS_HOST;
 192         beeper->input->id.vendor = 0x001f;
 193         beeper->input->id.product = 0x0001;
 194         beeper->input->id.version = 0x0100;
 195
 196         input_set_capability(beeper->input, EV_SND, SND_TONE);
 197         input_set_capability(beeper->input, EV_SND, SND_BELL);
 198
 199         beeper->input->event = pwm_beeper_event;
 200         beeper->input->close = pwm_beeper_close;
 201
 202         input_set_drvdata(beeper->input, beeper);
 203
 204         error = input_register_device(beeper->input);
 205         if (error) {
 206                 dev_err(dev, "Failed to register input device: %d\n", error);
 207                 return error;
 208         }
 209
 210         platform_set_drvdata(pdev, beeper);
 211
 212         return 0;
 213 }
 214
 215 static int __maybe_unused pwm_beeper_suspend(struct device *dev)
 216 {
 217         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 218
 219         /*
 220          * Spinlock is taken here is not to protect write to
 221          * beeper->suspended, but to ensure that pwm_beeper_event
 222          * does not re-submit work once flag is set.
 223          */
 224         spin_lock_irq(&beeper->input->event_lock);
 225         beeper->suspended = true;
 226         spin_unlock_irq(&beeper->input->event_lock);
 227
 228         pwm_beeper_stop(beeper);
 229
 230         return 0;
 231 }
 232
 233 static int __maybe_unused pwm_beeper_resume(struct device *dev)
 234 {
 235         struct pwm_beeper *beeper = dev_get_drvdata(dev);
 236
 237         spin_lock_irq(&beeper->input->event_lock);
 238         beeper->suspended = false;
 239         spin_unlock_irq(&beeper->input->event_lock);
 240
 241         /* Let worker figure out if we should resume beeping */
 242         schedule_work(&beeper->work);
 243
 244         return 0;
 245 }
 246
 247 static SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
 248                          pwm_beeper_suspend, pwm_beeper_resume);
 249
 250 #ifdef CONFIG_OF
 251 static const struct of_device_id pwm_beeper_match[] = {
 252         { .compatible = "pwm-beeper", },
 253         { },
 254 };
 255 MODULE_DEVICE_TABLE(of, pwm_beeper_match);
 256 #endif
 257
 258 static struct platform_driver pwm_beeper_driver = {
 259         .probe  = pwm_beeper_probe,
 260         .driver = {
 261                 .name   = "pwm-beeper",
 262                 .pm     = &pwm_beeper_pm_ops,
 263                 .of_match_table = of_match_ptr(pwm_beeper_match),
 264         },
 265 };
 266 module_platform_driver(pwm_beeper_driver);
 267
 268 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 269 MODULE_DESCRIPTION("PWM beeper driver");
 270 MODULE_LICENSE("GPL");
 271 MODULE_ALIAS("platform:pwm-beeper");