1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017 Sean Young <sean@mess.org>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/gpio/consumer.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <media/rc-core.h>
#define DRIVER_NAME "gpio-ir-tx"
#define DEVICE_NAME "GPIO IR Bit Banging Transmitter"
struct gpio_ir {
struct gpio_desc *gpio;
unsigned int carrier;
unsigned int duty_cycle;
/* we need a spinlock to hold the cpu while transmitting */
spinlock_t lock;
};
static const struct of_device_id gpio_ir_tx_of_match[] = {
{ .compatible = "gpio-ir-tx", },
{ },
};
MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
{
struct gpio_ir *gpio_ir = dev->priv;
gpio_ir->duty_cycle = duty_cycle;
return 0;
}
static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
{
struct gpio_ir *gpio_ir = dev->priv;
if (carrier > 500000)
return -EINVAL;
gpio_ir->carrier = carrier;
return 0;
}
static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
uint count)
{
unsigned long flags;
ktime_t edge;
s32 delta;
int i;
spin_lock_irqsave(&gpio_ir->lock, flags);
edge = ktime_get();
for (i = 0; i < count; i++) {
gpiod_set_value(gpio_ir->gpio, !(i % 2));
edge = ktime_add_us(edge, txbuf[i]);
delta = ktime_us_delta(edge, ktime_get());
if (delta > 0)
udelay(delta);
}
gpiod_set_value(gpio_ir->gpio, 0);
spin_unlock_irqrestore(&gpio_ir->lock, flags);
}
static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
uint count)
{
unsigned long flags;
ktime_t edge;
/*
* delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
* m68k ndelay(s64) does not compile; so use s32 rather than s64.
*/
s32 delta;
int i;
unsigned int pulse, space;
/* Ensure the dividend fits into 32 bit */
pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
gpio_ir->carrier);
space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
(NSEC_PER_SEC / 100), gpio_ir->carrier);
spin_lock_irqsave(&gpio_ir->lock, flags);
edge = ktime_get();
for (i = 0; i < count; i++) {
if (i % 2) {
// space
edge = ktime_add_us(edge, txbuf[i]);
delta = ktime_us_delta(edge, ktime_get());
if (delta > 0)
udelay(delta);
} else {
// pulse
ktime_t last = ktime_add_us(edge, txbuf[i]);
while (ktime_before(ktime_get(), last)) {
gpiod_set_value(gpio_ir->gpio, 1);
edge = ktime_add_ns(edge, pulse);
delta = ktime_to_ns(ktime_sub(edge,
ktime_get()));
if (delta > 0)
ndelay(delta);
gpiod_set_value(gpio_ir->gpio, 0);
edge = ktime_add_ns(edge, space);
delta = ktime_to_ns(ktime_sub(edge,
ktime_get()));
if (delta > 0)
ndelay(delta);
}
edge = last;
}
}
spin_unlock_irqrestore(&gpio_ir->lock, flags);
}
static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
unsigned int count)
{
struct gpio_ir *gpio_ir = dev->priv;
if (gpio_ir->carrier)
gpio_ir_tx_modulated(gpio_ir, txbuf, count);
else
gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);
return count;
}
static int gpio_ir_tx_probe(struct platform_device *pdev)
{
struct gpio_ir *gpio_ir;
struct rc_dev *rcdev;
int rc;
gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
if (!gpio_ir)
return -ENOMEM;
rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
if (!rcdev)
return -ENOMEM;
gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
if (IS_ERR(gpio_ir->gpio)) {
if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
PTR_ERR(gpio_ir->gpio));
return PTR_ERR(gpio_ir->gpio);
}
rcdev->priv = gpio_ir;
rcdev->driver_name = DRIVER_NAME;
rcdev->device_name = DEVICE_NAME;
rcdev->tx_ir = gpio_ir_tx;
rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
gpio_ir->carrier = 38000;
gpio_ir->duty_cycle = 50;
spin_lock_init(&gpio_ir->lock);
rc = devm_rc_register_device(&pdev->dev, rcdev);
if (rc < 0)
dev_err(&pdev->dev, "failed to register rc device\n");
return rc;
}
static struct platform_driver gpio_ir_tx_driver = {
.probe = gpio_ir_tx_probe,
.driver = {
.name = DRIVER_NAME,
.of_match_table = of_match_ptr(gpio_ir_tx_of_match),
},
};
module_platform_driver(gpio_ir_tx_driver);
MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");
MODULE_AUTHOR("Sean Young <sean@mess.org>");
MODULE_LICENSE("GPL");
|
