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: &state);
71
72 state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
73 pwm_set_relative_duty_cycle(state: &state, duty_cycle: pwm_ir->duty_cycle, scale: 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: &state);
80
81 edge = ktime_add_us(kt: edge, usec: txbuf[i]);
82 delta = ktime_us_delta(later: edge, earlier: ktime_get());
83 if (delta > 0)
84 usleep_range(min: delta, max: delta + 10);
85 }
86
87 state.enabled = false;
88 pwm_apply_might_sleep(pwm, state: &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: &state);
101
102 state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
103 pwm_set_relative_duty_cycle(state: &state, duty_cycle: pwm_ir->duty_cycle, scale: 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(timer: &pwm_ir->timer, tim: 0, mode: 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
121 /*
122 * If we happen to hit an odd latency spike, loop through the
123 * pulses until we catch up.
124 */
125 do {
126 u64 ns;
127
128 pwm_ir->state->enabled = !(pwm_ir->txbuf_index % 2);
129 pwm_apply_atomic(pwm: pwm_ir->pwm, state: pwm_ir->state);
130
131 if (pwm_ir->txbuf_index >= pwm_ir->txbuf_len) {
132 complete(&pwm_ir->tx_done);
133
134 return HRTIMER_NORESTART;
135 }
136
137 ns = US_TO_NS(pwm_ir->txbuf[pwm_ir->txbuf_index]);
138 hrtimer_add_expires_ns(timer, ns);
139
140 pwm_ir->txbuf_index++;
141 } while (hrtimer_expires_remaining(timer) > 0);
142
143 return HRTIMER_RESTART;
144}
145
146static int pwm_ir_probe(struct platform_device *pdev)
147{
148 struct pwm_ir *pwm_ir;
149 struct rc_dev *rcdev;
150 int rc;
151
152 pwm_ir = devm_kmalloc(dev: &pdev->dev, size: sizeof(*pwm_ir), GFP_KERNEL);
153 if (!pwm_ir)
154 return -ENOMEM;
155
156 pwm_ir->pwm = devm_pwm_get(dev: &pdev->dev, NULL);
157 if (IS_ERR(ptr: pwm_ir->pwm))
158 return PTR_ERR(ptr: pwm_ir->pwm);
159
160 pwm_ir->carrier = 38000;
161 pwm_ir->duty_cycle = 50;
162
163 rcdev = devm_rc_allocate_device(dev: &pdev->dev, RC_DRIVER_IR_RAW_TX);
164 if (!rcdev)
165 return -ENOMEM;
166
167 if (pwm_might_sleep(pwm: pwm_ir->pwm)) {
168 dev_info(&pdev->dev, "TX will not be accurate as PWM device might sleep\n");
169 rcdev->tx_ir = pwm_ir_tx_sleep;
170 } else {
171 init_completion(x: &pwm_ir->tx_done);
172 hrtimer_setup(timer: &pwm_ir->timer, function: pwm_ir_timer, CLOCK_MONOTONIC, mode: HRTIMER_MODE_REL);
173 rcdev->tx_ir = pwm_ir_tx_atomic;
174 }
175
176 rcdev->priv = pwm_ir;
177 rcdev->driver_name = DRIVER_NAME;
178 rcdev->device_name = DEVICE_NAME;
179 rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
180 rcdev->s_tx_carrier = pwm_ir_set_carrier;
181
182 rc = devm_rc_register_device(parent: &pdev->dev, dev: rcdev);
183 if (rc < 0)
184 dev_err(&pdev->dev, "failed to register rc device\n");
185
186 return rc;
187}
188
189static struct platform_driver pwm_ir_driver = {
190 .probe = pwm_ir_probe,
191 .driver = {
192 .name = DRIVER_NAME,
193 .of_match_table = pwm_ir_of_match,
194 },
195};
196module_platform_driver(pwm_ir_driver);
197
198MODULE_DESCRIPTION("PWM IR Transmitter");
199MODULE_AUTHOR("Sean Young <sean@mess.org>");
200MODULE_LICENSE("GPL");
201

source code of linux/drivers/media/rc/pwm-ir-tx.c