169 строки
4.0 KiB
C
169 строки
4.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2017 Sean Young <sean@mess.org>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/gpio/consumer.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <media/rc-core.h>
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#define DRIVER_NAME "gpio-ir-tx"
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#define DEVICE_NAME "GPIO IR Bit Banging Transmitter"
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struct gpio_ir {
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struct gpio_desc *gpio;
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unsigned int carrier;
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unsigned int duty_cycle;
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/* we need a spinlock to hold the cpu while transmitting */
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spinlock_t lock;
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};
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static const struct of_device_id gpio_ir_tx_of_match[] = {
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{ .compatible = "gpio-ir-tx", },
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{ },
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};
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MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
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static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
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{
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struct gpio_ir *gpio_ir = dev->priv;
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gpio_ir->duty_cycle = duty_cycle;
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return 0;
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}
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static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
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{
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struct gpio_ir *gpio_ir = dev->priv;
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if (!carrier)
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return -EINVAL;
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gpio_ir->carrier = carrier;
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return 0;
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}
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static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
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unsigned int count)
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{
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struct gpio_ir *gpio_ir = dev->priv;
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unsigned long flags;
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ktime_t edge;
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/*
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* delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
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* m68k ndelay(s64) does not compile; so use s32 rather than s64.
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*/
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s32 delta;
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int i;
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unsigned int pulse, space;
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/* Ensure the dividend fits into 32 bit */
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pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
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gpio_ir->carrier);
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space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
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(NSEC_PER_SEC / 100), gpio_ir->carrier);
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spin_lock_irqsave(&gpio_ir->lock, flags);
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edge = ktime_get();
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for (i = 0; i < count; i++) {
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if (i % 2) {
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// space
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edge = ktime_add_us(edge, txbuf[i]);
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delta = ktime_us_delta(edge, ktime_get());
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if (delta > 10) {
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spin_unlock_irqrestore(&gpio_ir->lock, flags);
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usleep_range(delta, delta + 10);
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spin_lock_irqsave(&gpio_ir->lock, flags);
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} else if (delta > 0) {
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udelay(delta);
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}
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} else {
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// pulse
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ktime_t last = ktime_add_us(edge, txbuf[i]);
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while (ktime_before(ktime_get(), last)) {
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gpiod_set_value(gpio_ir->gpio, 1);
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edge = ktime_add_ns(edge, pulse);
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delta = ktime_to_ns(ktime_sub(edge,
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ktime_get()));
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if (delta > 0)
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ndelay(delta);
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gpiod_set_value(gpio_ir->gpio, 0);
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edge = ktime_add_ns(edge, space);
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delta = ktime_to_ns(ktime_sub(edge,
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ktime_get()));
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if (delta > 0)
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ndelay(delta);
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}
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edge = last;
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}
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}
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spin_unlock_irqrestore(&gpio_ir->lock, flags);
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return count;
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}
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static int gpio_ir_tx_probe(struct platform_device *pdev)
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{
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struct gpio_ir *gpio_ir;
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struct rc_dev *rcdev;
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int rc;
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gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
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if (!gpio_ir)
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return -ENOMEM;
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rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
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if (!rcdev)
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return -ENOMEM;
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gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
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if (IS_ERR(gpio_ir->gpio)) {
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if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
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dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
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PTR_ERR(gpio_ir->gpio));
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return PTR_ERR(gpio_ir->gpio);
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}
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rcdev->priv = gpio_ir;
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rcdev->driver_name = DRIVER_NAME;
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rcdev->device_name = DEVICE_NAME;
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rcdev->tx_ir = gpio_ir_tx;
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rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
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rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
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gpio_ir->carrier = 38000;
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gpio_ir->duty_cycle = 50;
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spin_lock_init(&gpio_ir->lock);
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rc = devm_rc_register_device(&pdev->dev, rcdev);
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if (rc < 0)
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dev_err(&pdev->dev, "failed to register rc device\n");
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return rc;
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}
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static struct platform_driver gpio_ir_tx_driver = {
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.probe = gpio_ir_tx_probe,
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.driver = {
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.name = DRIVER_NAME,
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.of_match_table = of_match_ptr(gpio_ir_tx_of_match),
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},
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};
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module_platform_driver(gpio_ir_tx_driver);
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MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");
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MODULE_AUTHOR("Sean Young <sean@mess.org>");
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MODULE_LICENSE("GPL");
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