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"); 272