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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
24static const struct of_device_id gpio_ir_tx_of_match[] = {
25 { .compatible = "gpio-ir-tx", },
26 { },
27};
28MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
29
30static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
31{
32 struct gpio_ir *gpio_ir = dev->priv;
33
34 gpio_ir->duty_cycle = duty_cycle;
35
36 return 0;
37}
38
39static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
40{
41 struct gpio_ir *gpio_ir = dev->priv;
42
43 if (carrier > 500000)
44 return -EINVAL;
45
46 gpio_ir->carrier = carrier;
47
48 return 0;
49}
50
51static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
52 uint count)
53{
54 ktime_t edge;
55 s32 delta;
56 int i;
57
58 local_irq_disable();
59
60 edge = ktime_get();
61
62 for (i = 0; i < count; i++) {
63 gpiod_set_value(gpio_ir->gpio, !(i % 2));
64
65 edge = ktime_add_us(edge, txbuf[i]);
66 delta = ktime_us_delta(edge, ktime_get());
67 if (delta > 0)
68 udelay(delta);
69 }
70
71 gpiod_set_value(gpio_ir->gpio, 0);
72}
73
74static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
75 uint count)
76{
77 ktime_t edge;
78
79
80
81
82 s32 delta;
83 int i;
84 unsigned int pulse, space;
85
86
87 pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
88 gpio_ir->carrier);
89 space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
90 (NSEC_PER_SEC / 100), gpio_ir->carrier);
91
92 local_irq_disable();
93
94 edge = ktime_get();
95
96 for (i = 0; i < count; i++) {
97 if (i % 2) {
98
99 edge = ktime_add_us(edge, txbuf[i]);
100 delta = ktime_us_delta(edge, ktime_get());
101 if (delta > 0)
102 udelay(delta);
103 } else {
104
105 ktime_t last = ktime_add_us(edge, txbuf[i]);
106
107 while (ktime_before(ktime_get(), last)) {
108 gpiod_set_value(gpio_ir->gpio, 1);
109 edge = ktime_add_ns(edge, pulse);
110 delta = ktime_to_ns(ktime_sub(edge,
111 ktime_get()));
112 if (delta > 0)
113 ndelay(delta);
114 gpiod_set_value(gpio_ir->gpio, 0);
115 edge = ktime_add_ns(edge, space);
116 delta = ktime_to_ns(ktime_sub(edge,
117 ktime_get()));
118 if (delta > 0)
119 ndelay(delta);
120 }
121
122 edge = last;
123 }
124 }
125}
126
127static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
128 unsigned int count)
129{
130 struct gpio_ir *gpio_ir = dev->priv;
131 unsigned long flags;
132
133 local_irq_save(flags);
134 if (gpio_ir->carrier)
135 gpio_ir_tx_modulated(gpio_ir, txbuf, count);
136 else
137 gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);
138 local_irq_restore(flags);
139
140 return count;
141}
142
143static int gpio_ir_tx_probe(struct platform_device *pdev)
144{
145 struct gpio_ir *gpio_ir;
146 struct rc_dev *rcdev;
147 int rc;
148
149 gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
150 if (!gpio_ir)
151 return -ENOMEM;
152
153 rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
154 if (!rcdev)
155 return -ENOMEM;
156
157 gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
158 if (IS_ERR(gpio_ir->gpio)) {
159 if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
160 dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
161 PTR_ERR(gpio_ir->gpio));
162 return PTR_ERR(gpio_ir->gpio);
163 }
164
165 rcdev->priv = gpio_ir;
166 rcdev->driver_name = DRIVER_NAME;
167 rcdev->device_name = DEVICE_NAME;
168 rcdev->tx_ir = gpio_ir_tx;
169 rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
170 rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
171
172 gpio_ir->carrier = 38000;
173 gpio_ir->duty_cycle = 50;
174
175 rc = devm_rc_register_device(&pdev->dev, rcdev);
176 if (rc < 0)
177 dev_err(&pdev->dev, "failed to register rc device\n");
178
179 return rc;
180}
181
182static struct platform_driver gpio_ir_tx_driver = {
183 .probe = gpio_ir_tx_probe,
184 .driver = {
185 .name = DRIVER_NAME,
186 .of_match_table = of_match_ptr(gpio_ir_tx_of_match),
187 },
188};
189module_platform_driver(gpio_ir_tx_driver);
190
191MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");
192MODULE_AUTHOR("Sean Young <sean@mess.org>");
193MODULE_LICENSE("GPL");
194
