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
pwm_beeper_on(struct pwm_beeper * beeper,unsigned long period)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
pwm_beeper_off(struct pwm_beeper * beeper)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
pwm_beeper_work(struct work_struct * work)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
pwm_beeper_event(struct input_dev * input,unsigned int type,unsigned int code,int value)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
pwm_beeper_stop(struct pwm_beeper * beeper)109 static void pwm_beeper_stop(struct pwm_beeper *beeper)
110 {
111 cancel_work_sync(&beeper->work);
112 pwm_beeper_off(beeper);
113 }
114
pwm_beeper_close(struct input_dev * input)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
pwm_beeper_probe(struct platform_device * pdev)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
pwm_beeper_suspend(struct device * dev)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 spin_lock_irq(&beeper->input->event_lock);
207 beeper->suspended = true;
208 spin_unlock_irq(&beeper->input->event_lock);
209
210 pwm_beeper_stop(beeper);
211
212 return 0;
213 }
214
pwm_beeper_resume(struct device * dev)215 static int pwm_beeper_resume(struct device *dev)
216 {
217 struct pwm_beeper *beeper = dev_get_drvdata(dev);
218
219 spin_lock_irq(&beeper->input->event_lock);
220 beeper->suspended = false;
221 spin_unlock_irq(&beeper->input->event_lock);
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