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
18struct 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
31static 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_state(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
59static 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
69static 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
80static 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
109static void pwm_beeper_stop(struct pwm_beeper *beeper)
110{
111	cancel_work_sync(&beeper->work);
112	pwm_beeper_off(beeper);
113}
114
115static 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
122static 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		error = PTR_ERR(beeper->pwm);
137		if (error != -EPROBE_DEFER)
138			dev_err(dev, "Failed to request PWM device: %d\n",
139				error);
140		return error;
141	}
142
143	/* Sync up PWM state and ensure it is off. */
144	pwm_init_state(beeper->pwm, &state);
145	state.enabled = false;
146	error = pwm_apply_state(beeper->pwm, &state);
147	if (error) {
148		dev_err(dev, "failed to apply initial PWM state: %d\n",
149			error);
150		return error;
151	}
152
153	beeper->amplifier = devm_regulator_get(dev, "amp");
154	if (IS_ERR(beeper->amplifier)) {
155		error = PTR_ERR(beeper->amplifier);
156		if (error != -EPROBE_DEFER)
157			dev_err(dev, "Failed to get 'amp' regulator: %d\n",
158				error);
159		return error;
160	}
161
162	INIT_WORK(&beeper->work, pwm_beeper_work);
163
164	error = device_property_read_u32(dev, "beeper-hz", &bell_frequency);
165	if (error) {
166		bell_frequency = 1000;
167		dev_dbg(dev,
168			"failed to parse 'beeper-hz' property, using default: %uHz\n",
169			bell_frequency);
170	}
171
172	beeper->bell_frequency = bell_frequency;
173
174	beeper->input = devm_input_allocate_device(dev);
175	if (!beeper->input) {
176		dev_err(dev, "Failed to allocate input device\n");
177		return -ENOMEM;
178	}
179
180	beeper->input->name = "pwm-beeper";
181	beeper->input->phys = "pwm/input0";
182	beeper->input->id.bustype = BUS_HOST;
183	beeper->input->id.vendor = 0x001f;
184	beeper->input->id.product = 0x0001;
185	beeper->input->id.version = 0x0100;
186
187	input_set_capability(beeper->input, EV_SND, SND_TONE);
188	input_set_capability(beeper->input, EV_SND, SND_BELL);
189
190	beeper->input->event = pwm_beeper_event;
191	beeper->input->close = pwm_beeper_close;
192
193	input_set_drvdata(beeper->input, beeper);
194
195	error = input_register_device(beeper->input);
196	if (error) {
197		dev_err(dev, "Failed to register input device: %d\n", error);
198		return error;
199	}
200
201	platform_set_drvdata(pdev, beeper);
202
203	return 0;
204}
205
206static int __maybe_unused pwm_beeper_suspend(struct device *dev)
207{
208	struct pwm_beeper *beeper = dev_get_drvdata(dev);
209
210	/*
211	 * Spinlock is taken here is not to protect write to
212	 * beeper->suspended, but to ensure that pwm_beeper_event
213	 * does not re-submit work once flag is set.
214	 */
215	spin_lock_irq(&beeper->input->event_lock);
216	beeper->suspended = true;
217	spin_unlock_irq(&beeper->input->event_lock);
218
219	pwm_beeper_stop(beeper);
220
221	return 0;
222}
223
224static int __maybe_unused pwm_beeper_resume(struct device *dev)
225{
226	struct pwm_beeper *beeper = dev_get_drvdata(dev);
227
228	spin_lock_irq(&beeper->input->event_lock);
229	beeper->suspended = false;
230	spin_unlock_irq(&beeper->input->event_lock);
231
232	/* Let worker figure out if we should resume beeping */
233	schedule_work(&beeper->work);
234
235	return 0;
236}
237
238static SIMPLE_DEV_PM_OPS(pwm_beeper_pm_ops,
239			 pwm_beeper_suspend, pwm_beeper_resume);
240
241#ifdef CONFIG_OF
242static const struct of_device_id pwm_beeper_match[] = {
243	{ .compatible = "pwm-beeper", },
244	{ },
245};
246MODULE_DEVICE_TABLE(of, pwm_beeper_match);
247#endif
248
249static struct platform_driver pwm_beeper_driver = {
250	.probe	= pwm_beeper_probe,
251	.driver = {
252		.name	= "pwm-beeper",
253		.pm	= &pwm_beeper_pm_ops,
254		.of_match_table = of_match_ptr(pwm_beeper_match),
255	},
256};
257module_platform_driver(pwm_beeper_driver);
258
259MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
260MODULE_DESCRIPTION("PWM beeper driver");
261MODULE_LICENSE("GPL");
262MODULE_ALIAS("platform:pwm-beeper");
263