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5
6#include <linux/kernel.h>
7#include <linux/module.h>
8#include <linux/gpio/consumer.h>
9#include <linux/delay.h>
10#include <linux/slab.h>
11#include <linux/of.h>
12#include <linux/platform_device.h>
13#include <media/rc-core.h>
14
15#define DRIVER_NAME "gpio-ir-tx"
16#define DEVICE_NAME "GPIO IR Bit Banging Transmitter"
17
18struct gpio_ir {
19 struct gpio_desc *gpio;
20 unsigned int carrier;
21 unsigned int duty_cycle;
22
23 spinlock_t lock;
24};
25
26static const struct of_device_id gpio_ir_tx_of_match[] = {
27 { .compatible = "gpio-ir-tx", },
28 { },
29};
30MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
31
32static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
33{
34 struct gpio_ir *gpio_ir = dev->priv;
35
36 gpio_ir->duty_cycle = duty_cycle;
37
38 return 0;
39}
40
41static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
42{
43 struct gpio_ir *gpio_ir = dev->priv;
44
45 if (!carrier)
46 return -EINVAL;
47
48 gpio_ir->carrier = carrier;
49
50 return 0;
51}
52
53static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
54 unsigned int count)
55{
56 struct gpio_ir *gpio_ir = dev->priv;
57 unsigned long flags;
58 ktime_t edge;
59
60
61
62
63 s32 delta;
64 int i;
65 unsigned int pulse, space;
66
67
68 pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
69 gpio_ir->carrier);
70 space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
71 (NSEC_PER_SEC / 100), gpio_ir->carrier);
72
73 spin_lock_irqsave(&gpio_ir->lock, flags);
74
75 edge = ktime_get();
76
77 for (i = 0; i < count; i++) {
78 if (i % 2) {
79
80 edge = ktime_add_us(edge, txbuf[i]);
81 delta = ktime_us_delta(edge, ktime_get());
82 if (delta > 10) {
83 spin_unlock_irqrestore(&gpio_ir->lock, flags);
84 usleep_range(delta, delta + 10);
85 spin_lock_irqsave(&gpio_ir->lock, flags);
86 } else if (delta > 0) {
87 udelay(delta);
88 }
89 } else {
90
91 ktime_t last = ktime_add_us(edge, txbuf[i]);
92
93 while (ktime_before(ktime_get(), last)) {
94 gpiod_set_value(gpio_ir->gpio, 1);
95 edge = ktime_add_ns(edge, pulse);
96 delta = ktime_to_ns(ktime_sub(edge,
97 ktime_get()));
98 if (delta > 0)
99 ndelay(delta);
100 gpiod_set_value(gpio_ir->gpio, 0);
101 edge = ktime_add_ns(edge, space);
102 delta = ktime_to_ns(ktime_sub(edge,
103 ktime_get()));
104 if (delta > 0)
105 ndelay(delta);
106 }
107
108 edge = last;
109 }
110 }
111
112 spin_unlock_irqrestore(&gpio_ir->lock, flags);
113
114 return count;
115}
116
117static int gpio_ir_tx_probe(struct platform_device *pdev)
118{
119 struct gpio_ir *gpio_ir;
120 struct rc_dev *rcdev;
121 int rc;
122
123 gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
124 if (!gpio_ir)
125 return -ENOMEM;
126
127 rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
128 if (!rcdev)
129 return -ENOMEM;
130
131 gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
132 if (IS_ERR(gpio_ir->gpio)) {
133 if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
134 dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
135 PTR_ERR(gpio_ir->gpio));
136 return PTR_ERR(gpio_ir->gpio);
137 }
138
139 rcdev->priv = gpio_ir;
140 rcdev->driver_name = DRIVER_NAME;
141 rcdev->device_name = DEVICE_NAME;
142 rcdev->tx_ir = gpio_ir_tx;
143 rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
144 rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
145
146 gpio_ir->carrier = 38000;
147 gpio_ir->duty_cycle = 50;
148 spin_lock_init(&gpio_ir->lock);
149
150 rc = devm_rc_register_device(&pdev->dev, rcdev);
151 if (rc < 0)
152 dev_err(&pdev->dev, "failed to register rc device\n");
153
154 return rc;
155}
156
157static struct platform_driver gpio_ir_tx_driver = {
158 .probe = gpio_ir_tx_probe,
159 .driver = {
160 .name = DRIVER_NAME,
161 .of_match_table = of_match_ptr(gpio_ir_tx_of_match),
162 },
163};
164module_platform_driver(gpio_ir_tx_driver);
165
166MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");
167MODULE_AUTHOR("Sean Young <sean@mess.org>");
168MODULE_LICENSE("GPL");
169
