xref: /linux/drivers/media/rc/pwm-ir-tx.c (revision c5448d46b3995c0b477f6bb04f313af3d57665c4)
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 
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_ir->pwm, 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 
pwm_ir_probe(struct platform_device * pdev)146 static 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(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
153 	if (!pwm_ir)
154 		return -ENOMEM;
155 
156 	pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
157 	if (IS_ERR(pwm_ir->pwm))
158 		return PTR_ERR(pwm_ir->pwm);
159 
160 	pwm_ir->carrier = 38000;
161 	pwm_ir->duty_cycle = 50;
162 
163 	rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
164 	if (!rcdev)
165 		return -ENOMEM;
166 
167 	if (pwm_might_sleep(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(&pwm_ir->tx_done);
172 		hrtimer_setup(&pwm_ir->timer, pwm_ir_timer, CLOCK_MONOTONIC, 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(&pdev->dev, rcdev);
183 	if (rc < 0)
184 		dev_err(&pdev->dev, "failed to register rc device\n");
185 
186 	return rc;
187 }
188 
189 static 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 };
196 module_platform_driver(pwm_ir_driver);
197 
198 MODULE_DESCRIPTION("PWM IR Transmitter");
199 MODULE_AUTHOR("Sean Young <sean@mess.org>");
200 MODULE_LICENSE("GPL");
201