1 /*
2 * Copyright (C) 2017 Sean Young <sean@mess.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2, or
6 * (at your option) any later version.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/pwm.h>
17 #include <linux/delay.h>
18 #include <linux/slab.h>
19 #include <linux/of.h>
20 #include <linux/platform_device.h>
21 #include <media/rc-core.h>
22
23 #define DRIVER_NAME "pwm-ir-tx"
24 #define DEVICE_NAME "PWM IR Transmitter"
25
26 struct pwm_ir {
27 struct pwm_device *pwm;
28 unsigned int carrier;
29 unsigned int duty_cycle;
30 };
31
32 static const struct of_device_id pwm_ir_of_match[] = {
33 { .compatible = "pwm-ir-tx", },
34 { },
35 };
36 MODULE_DEVICE_TABLE(of, pwm_ir_of_match);
37
pwm_ir_set_duty_cycle(struct rc_dev * dev,u32 duty_cycle)38 static int pwm_ir_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
39 {
40 struct pwm_ir *pwm_ir = dev->priv;
41
42 pwm_ir->duty_cycle = duty_cycle;
43
44 return 0;
45 }
46
pwm_ir_set_carrier(struct rc_dev * dev,u32 carrier)47 static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier)
48 {
49 struct pwm_ir *pwm_ir = dev->priv;
50
51 if (!carrier)
52 return -EINVAL;
53
54 pwm_ir->carrier = carrier;
55
56 return 0;
57 }
58
pwm_ir_tx(struct rc_dev * dev,unsigned int * txbuf,unsigned int count)59 static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
60 unsigned int count)
61 {
62 struct pwm_ir *pwm_ir = dev->priv;
63 struct pwm_device *pwm = pwm_ir->pwm;
64 int i, duty, period;
65 ktime_t edge;
66 long delta;
67
68 period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);
69 duty = DIV_ROUND_CLOSEST(pwm_ir->duty_cycle * period, 100);
70
71 pwm_config(pwm, duty, period);
72
73 edge = ktime_get();
74
75 for (i = 0; i < count; i++) {
76 if (i % 2) // space
77 pwm_disable(pwm);
78 else
79 pwm_enable(pwm);
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 pwm_disable(pwm);
88
89 return count;
90 }
91
pwm_ir_probe(struct platform_device * pdev)92 static int pwm_ir_probe(struct platform_device *pdev)
93 {
94 struct pwm_ir *pwm_ir;
95 struct rc_dev *rcdev;
96 int rc;
97
98 pwm_ir = devm_kmalloc(&pdev->dev, sizeof(*pwm_ir), GFP_KERNEL);
99 if (!pwm_ir)
100 return -ENOMEM;
101
102 pwm_ir->pwm = devm_pwm_get(&pdev->dev, NULL);
103 if (IS_ERR(pwm_ir->pwm))
104 return PTR_ERR(pwm_ir->pwm);
105
106 pwm_ir->carrier = 38000;
107 pwm_ir->duty_cycle = 50;
108
109 rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
110 if (!rcdev)
111 return -ENOMEM;
112
113 rcdev->priv = pwm_ir;
114 rcdev->driver_name = DRIVER_NAME;
115 rcdev->device_name = DEVICE_NAME;
116 rcdev->tx_ir = pwm_ir_tx;
117 rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;
118 rcdev->s_tx_carrier = pwm_ir_set_carrier;
119
120 rc = devm_rc_register_device(&pdev->dev, rcdev);
121 if (rc < 0)
122 dev_err(&pdev->dev, "failed to register rc device\n");
123
124 return rc;
125 }
126
127 static struct platform_driver pwm_ir_driver = {
128 .probe = pwm_ir_probe,
129 .driver = {
130 .name = DRIVER_NAME,
131 .of_match_table = of_match_ptr(pwm_ir_of_match),
132 },
133 };
134 module_platform_driver(pwm_ir_driver);
135
136 MODULE_DESCRIPTION("PWM IR Transmitter");
137 MODULE_AUTHOR("Sean Young <sean@mess.org>");
138 MODULE_LICENSE("GPL");
139
