1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (C) 2017 Sean Young <sean@mess.org>
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>
12 #include <linux/platform_device.h>
13 #include <media/rc-core.h>
15 #define DRIVER_NAME "gpio-ir-tx"
16 #define DEVICE_NAME "GPIO IR Bit Banging Transmitter"
19 struct gpio_desc *gpio;
21 unsigned int duty_cycle;
22 /* we need a spinlock to hold the cpu while transmitting */
26 static const struct of_device_id gpio_ir_tx_of_match[] = {
27 { .compatible = "gpio-ir-tx", },
30 MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
32 static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
34 struct gpio_ir *gpio_ir = dev->priv;
36 gpio_ir->duty_cycle = duty_cycle;
41 static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
43 struct gpio_ir *gpio_ir = dev->priv;
48 gpio_ir->carrier = carrier;
53 static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
61 spin_lock_irqsave(&gpio_ir->lock, flags);
65 for (i = 0; i < count; i++) {
66 gpiod_set_value(gpio_ir->gpio, !(i % 2));
68 edge = ktime_add_us(edge, txbuf[i]);
69 delta = ktime_us_delta(edge, ktime_get());
74 gpiod_set_value(gpio_ir->gpio, 0);
76 spin_unlock_irqrestore(&gpio_ir->lock, flags);
79 static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
85 * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
86 * m68k ndelay(s64) does not compile; so use s32 rather than s64.
90 unsigned int pulse, space;
92 /* Ensure the dividend fits into 32 bit */
93 pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
95 space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
96 (NSEC_PER_SEC / 100), gpio_ir->carrier);
98 spin_lock_irqsave(&gpio_ir->lock, flags);
102 for (i = 0; i < count; i++) {
105 edge = ktime_add_us(edge, txbuf[i]);
106 delta = ktime_us_delta(edge, ktime_get());
111 ktime_t last = ktime_add_us(edge, txbuf[i]);
113 while (ktime_before(ktime_get(), last)) {
114 gpiod_set_value(gpio_ir->gpio, 1);
115 edge = ktime_add_ns(edge, pulse);
116 delta = ktime_to_ns(ktime_sub(edge,
120 gpiod_set_value(gpio_ir->gpio, 0);
121 edge = ktime_add_ns(edge, space);
122 delta = ktime_to_ns(ktime_sub(edge,
132 spin_unlock_irqrestore(&gpio_ir->lock, flags);
135 static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
138 struct gpio_ir *gpio_ir = dev->priv;
140 if (gpio_ir->carrier)
141 gpio_ir_tx_modulated(gpio_ir, txbuf, count);
143 gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);
148 static int gpio_ir_tx_probe(struct platform_device *pdev)
150 struct gpio_ir *gpio_ir;
151 struct rc_dev *rcdev;
154 gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
158 rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
162 gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
163 if (IS_ERR(gpio_ir->gpio)) {
164 if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
165 dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
166 PTR_ERR(gpio_ir->gpio));
167 return PTR_ERR(gpio_ir->gpio);
170 rcdev->priv = gpio_ir;
171 rcdev->driver_name = DRIVER_NAME;
172 rcdev->device_name = DEVICE_NAME;
173 rcdev->tx_ir = gpio_ir_tx;
174 rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
175 rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
177 gpio_ir->carrier = 38000;
178 gpio_ir->duty_cycle = 50;
179 spin_lock_init(&gpio_ir->lock);
181 rc = devm_rc_register_device(&pdev->dev, rcdev);
183 dev_err(&pdev->dev, "failed to register rc device\n");
188 static struct platform_driver gpio_ir_tx_driver = {
189 .probe = gpio_ir_tx_probe,
192 .of_match_table = of_match_ptr(gpio_ir_tx_of_match),
195 module_platform_driver(gpio_ir_tx_driver);
197 MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");
198 MODULE_AUTHOR("Sean Young <sean@mess.org>");
199 MODULE_LICENSE("GPL");