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"); 259