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"); 254