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/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 | |
18 | struct gpio_ir { |
19 | struct gpio_desc *gpio; |
20 | unsigned int carrier; |
21 | unsigned int duty_cycle; |
22 | }; |
23 | |
24 | static const struct of_device_id gpio_ir_tx_of_match[] = { |
25 | { .compatible = "gpio-ir-tx" , }, |
26 | { }, |
27 | }; |
28 | MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match); |
29 | |
30 | static 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 | |
39 | static 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 | |
51 | static void delay_until(ktime_t until) |
52 | { |
53 | /* |
54 | * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on |
55 | * m68k ndelay(s64) does not compile; so use s32 rather than s64. |
56 | */ |
57 | s32 delta; |
58 | |
59 | while (true) { |
60 | delta = ktime_us_delta(later: until, earlier: ktime_get()); |
61 | if (delta <= 0) |
62 | return; |
63 | |
64 | /* udelay more than 1ms may not work */ |
65 | if (delta >= 1000) { |
66 | mdelay(delta / 1000); |
67 | continue; |
68 | } |
69 | |
70 | udelay(delta); |
71 | break; |
72 | } |
73 | } |
74 | |
75 | static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf, |
76 | uint count) |
77 | { |
78 | ktime_t edge; |
79 | int i; |
80 | |
81 | local_irq_disable(); |
82 | |
83 | edge = ktime_get(); |
84 | |
85 | for (i = 0; i < count; i++) { |
86 | gpiod_set_value(desc: gpio_ir->gpio, value: !(i % 2)); |
87 | |
88 | edge = ktime_add_us(kt: edge, usec: txbuf[i]); |
89 | delay_until(until: edge); |
90 | } |
91 | |
92 | gpiod_set_value(desc: gpio_ir->gpio, value: 0); |
93 | } |
94 | |
95 | static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf, |
96 | uint count) |
97 | { |
98 | ktime_t edge; |
99 | /* |
100 | * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on |
101 | * m68k ndelay(s64) does not compile; so use s32 rather than s64. |
102 | */ |
103 | s32 delta; |
104 | int i; |
105 | unsigned int pulse, space; |
106 | |
107 | /* Ensure the dividend fits into 32 bit */ |
108 | pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100), |
109 | gpio_ir->carrier); |
110 | space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) * |
111 | (NSEC_PER_SEC / 100), gpio_ir->carrier); |
112 | |
113 | local_irq_disable(); |
114 | |
115 | edge = ktime_get(); |
116 | |
117 | for (i = 0; i < count; i++) { |
118 | if (i % 2) { |
119 | // space |
120 | edge = ktime_add_us(kt: edge, usec: txbuf[i]); |
121 | delay_until(until: edge); |
122 | } else { |
123 | // pulse |
124 | ktime_t last = ktime_add_us(kt: edge, usec: txbuf[i]); |
125 | |
126 | while (ktime_before(cmp1: ktime_get(), cmp2: last)) { |
127 | gpiod_set_value(desc: gpio_ir->gpio, value: 1); |
128 | edge = ktime_add_ns(edge, pulse); |
129 | delta = ktime_to_ns(ktime_sub(edge, |
130 | ktime_get())); |
131 | if (delta > 0) |
132 | ndelay(delta); |
133 | gpiod_set_value(desc: gpio_ir->gpio, value: 0); |
134 | edge = ktime_add_ns(edge, space); |
135 | delta = ktime_to_ns(ktime_sub(edge, |
136 | ktime_get())); |
137 | if (delta > 0) |
138 | ndelay(delta); |
139 | } |
140 | |
141 | edge = last; |
142 | } |
143 | } |
144 | } |
145 | |
146 | static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf, |
147 | unsigned int count) |
148 | { |
149 | struct gpio_ir *gpio_ir = dev->priv; |
150 | unsigned long flags; |
151 | |
152 | local_irq_save(flags); |
153 | if (gpio_ir->carrier) |
154 | gpio_ir_tx_modulated(gpio_ir, txbuf, count); |
155 | else |
156 | gpio_ir_tx_unmodulated(gpio_ir, txbuf, count); |
157 | local_irq_restore(flags); |
158 | |
159 | return count; |
160 | } |
161 | |
162 | static int gpio_ir_tx_probe(struct platform_device *pdev) |
163 | { |
164 | struct gpio_ir *gpio_ir; |
165 | struct rc_dev *rcdev; |
166 | int rc; |
167 | |
168 | gpio_ir = devm_kmalloc(dev: &pdev->dev, size: sizeof(*gpio_ir), GFP_KERNEL); |
169 | if (!gpio_ir) |
170 | return -ENOMEM; |
171 | |
172 | rcdev = devm_rc_allocate_device(dev: &pdev->dev, RC_DRIVER_IR_RAW_TX); |
173 | if (!rcdev) |
174 | return -ENOMEM; |
175 | |
176 | gpio_ir->gpio = devm_gpiod_get(dev: &pdev->dev, NULL, flags: GPIOD_OUT_LOW); |
177 | if (IS_ERR(ptr: gpio_ir->gpio)) |
178 | return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: gpio_ir->gpio), |
179 | fmt: "Failed to get gpio\n" ); |
180 | |
181 | rcdev->priv = gpio_ir; |
182 | rcdev->driver_name = DRIVER_NAME; |
183 | rcdev->device_name = DEVICE_NAME; |
184 | rcdev->tx_ir = gpio_ir_tx; |
185 | rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle; |
186 | rcdev->s_tx_carrier = gpio_ir_tx_set_carrier; |
187 | |
188 | gpio_ir->carrier = 38000; |
189 | gpio_ir->duty_cycle = 50; |
190 | |
191 | rc = devm_rc_register_device(parent: &pdev->dev, dev: rcdev); |
192 | if (rc < 0) |
193 | dev_err(&pdev->dev, "failed to register rc device\n" ); |
194 | |
195 | return rc; |
196 | } |
197 | |
198 | static struct platform_driver gpio_ir_tx_driver = { |
199 | .probe = gpio_ir_tx_probe, |
200 | .driver = { |
201 | .name = DRIVER_NAME, |
202 | .of_match_table = gpio_ir_tx_of_match, |
203 | }, |
204 | }; |
205 | module_platform_driver(gpio_ir_tx_driver); |
206 | |
207 | MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter" ); |
208 | MODULE_AUTHOR("Sean Young <sean@mess.org>" ); |
209 | MODULE_LICENSE("GPL" ); |
210 | |