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
20 struct 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
32 static const struct of_device_id pwm_ir_of_match[] = {
33 { .compatible = "pwm-ir-tx", },
34 { .compatible = "nokia,n900-ir" },
35 { },
36 };
37 MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
38
pwm_ir_set_duty_cycle(struct rc_dev * dev,u32 duty_cycle)39 static 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
pwm_ir_set_carrier(struct rc_dev * dev,u32 carrier)48 static 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
pwm_ir_tx_sleep(struct rc_dev * dev,unsigned int * txbuf,unsigned int count)60 static 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
pwm_ir_tx_atomic(struct rc_dev * dev,unsigned int * txbuf,unsigned int count)93 static 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
pwm_ir_timer(struct hrtimer * timer)117 static 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
pwm_ir_probe(struct platform_device * pdev)149 static 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
193 static 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 };
200 module_platform_driver(pwm_ir_driver);
201
202 MODULE_DESCRIPTION("PWM IR Transmitter");
203 MODULE_AUTHOR("Sean Young <sean@mess.org>");
204 MODULE_LICENSE("GPL");
205