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