1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2017 Sean Young <sean@mess.org>
4 */
5
6#include <linux/kernel.h>
7#include <linux/module.h>
8#include <linux/pwm.h>
9#include <linux/delay.h>
10#include <linux/slab.h>
11#include <linux/of.h>
12#include <linux/platform_device.h>
13#include <linux/hrtimer.h>
14#include <linux/completion.h>
15#include <media/rc-core.h>
16
17#define DRIVER_NAME	"pwm-ir-tx"
18#define DEVICE_NAME	"PWM IR Transmitter"
19
20struct pwm_ir {
21	struct pwm_device *pwm;
22	struct hrtimer timer;
23	struct completion tx_done;
24	struct pwm_state *state;
25	u32 carrier;
26	u32 duty_cycle;
27	const unsigned int *txbuf;
28	unsigned int txbuf_len;
29	unsigned int txbuf_index;
30};
31
32static const struct of_device_id pwm_ir_of_match[] = {
33	{ .compatible = "pwm-ir-tx", },
34	{ .compatible = "nokia,n900-ir" },
35	{ },
36};
37MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
38
39static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
40{
41	struct pwm_ir *pwm_ir = dev->priv;
42
43	pwm_ir->duty_cycle = duty_cycle;
44
45	return 0;
46}
47
48static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
49{
50	struct pwm_ir *pwm_ir = dev->priv;
51
52	if (!carrier)
53		return -EINVAL;
54
55	pwm_ir->carrier = carrier;
56
57	return 0;
58}
59
60static int pwm_ir_tx_sleep(struct rc_dev *dev, unsigned int *txbuf,
61			   unsigned int count)
62{
63	struct pwm_ir *pwm_ir = dev->priv;
64	struct pwm_device *pwm = pwm_ir->pwm;
65	struct pwm_state state;
66	int i;
67	ktime_t edge;
68	long delta;
69
70	pwm_init_state(pwm, &state);
71
72	state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
73	pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);
74
75	edge = ktime_get();
76
77	for (i = 0; i < count; i++) {
78		state.enabled = !(i % 2);
79		pwm_apply_might_sleep(pwm, &state);
80
81		edge = ktime_add_us(edge, txbuf[i]);
82		delta = ktime_us_delta(edge, ktime_get());
83		if (delta > 0)
84			usleep_range(delta, delta + 10);
85	}
86
87	state.enabled = false;
88	pwm_apply_might_sleep(pwm, &state);
89
90	return count;
91}
92
93static int pwm_ir_tx_atomic(struct rc_dev *dev, unsigned int *txbuf,
94			    unsigned int count)
95{
96	struct pwm_ir *pwm_ir = dev->priv;
97	struct pwm_device *pwm = pwm_ir->pwm;
98	struct pwm_state state;
99
100	pwm_init_state(pwm, &state);
101
102	state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
103	pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);
104
105	pwm_ir->txbuf = txbuf;
106	pwm_ir->txbuf_len = count;
107	pwm_ir->txbuf_index = 0;
108	pwm_ir->state = &state;
109
110	hrtimer_start(&pwm_ir->timer, 0, HRTIMER_MODE_REL);
111
112	wait_for_completion(&pwm_ir->tx_done);
113
114	return count;
115}
116
117static enum hrtimer_restart pwm_ir_timer(struct hrtimer *timer)
118{
119	struct pwm_ir *pwm_ir = container_of(timer, struct pwm_ir, timer);
120	ktime_t now;
121
122	/*
123	 * If we happen to hit an odd latency spike, loop through the
124	 * pulses until we catch up.
125	 */
126	do {
127		u64 ns;
128
129		pwm_ir->state->enabled = !(pwm_ir->txbuf_index % 2);
130		pwm_apply_atomic(pwm_ir->pwm, pwm_ir->state);
131
132		if (pwm_ir->txbuf_index >= pwm_ir->txbuf_len) {
133			complete(&pwm_ir->tx_done);
134
135			return HRTIMER_NORESTART;
136		}
137
138		ns = US_TO_NS(pwm_ir->txbuf[pwm_ir->txbuf_index]);
139		hrtimer_add_expires_ns(timer, ns);
140
141		pwm_ir->txbuf_index++;
142
143		now = timer->base->get_time();
144	} while (hrtimer_get_expires_tv64(timer) < now);
145
146	return HRTIMER_RESTART;
147}
148
149static int pwm_ir_probe(struct platform_device *pdev)
150{
151	struct pwm_ir *pwm_ir;
152	struct rc_dev *rcdev;
153	int rc;
154
155	pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
156	if (!pwm_ir)
157		return -ENOMEM;
158
159	pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
160	if (IS_ERR(pwm_ir->pwm))
161		return PTR_ERR(pwm_ir->pwm);
162
163	pwm_ir->carrier = 38000;
164	pwm_ir->duty_cycle = 50;
165
166	rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
167	if (!rcdev)
168		return -ENOMEM;
169
170	if (pwm_might_sleep(pwm_ir->pwm)) {
171		dev_info(&pdev->dev, "TX will not be accurate as PWM device might sleep\n");
172		rcdev->tx_ir = pwm_ir_tx_sleep;
173	} else {
174		init_completion(&pwm_ir->tx_done);
175		hrtimer_init(&pwm_ir->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
176		pwm_ir->timer.function = pwm_ir_timer;
177		rcdev->tx_ir = pwm_ir_tx_atomic;
178	}
179
180	rcdev->priv = pwm_ir;
181	rcdev->driver_name = DRIVER_NAME;
182	rcdev->device_name = DEVICE_NAME;
183	rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
184	rcdev->s_tx_carrier = pwm_ir_set_carrier;
185
186	rc = devm_rc_register_device(&pdev->dev, rcdev);
187	if (rc < 0)
188		dev_err(&pdev->dev, "failed to register rc device\n");
189
190	return rc;
191}
192
193static struct platform_driver pwm_ir_driver = {
194	.probe = pwm_ir_probe,
195	.driver = {
196		.name	= DRIVER_NAME,
197		.of_match_table = pwm_ir_of_match,
198	},
199};
200module_platform_driver(pwm_ir_driver);
201
202MODULE_DESCRIPTION("PWM IR Transmitter");
203MODULE_AUTHOR("Sean Young <sean@mess.org>");
204MODULE_LICENSE("GPL");
205