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// 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;
};
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 delay_until(ktime_t until)
{
/*
* 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;
while (true) {
delta = ktime_us_delta(until, ktime_get());
if (delta <= 0)
return;
/* udelay more than 1ms may not work */
if (delta >= 1000) {
mdelay(delta / 1000);
continue;
}
udelay(delta);
break;
}
}
static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
uint count)
{
ktime_t edge;
int i;
local_irq_disable();
edge = ktime_get();
for (i = 0; i < count; i++) {
gpiod_set_value(gpio_ir->gpio, !(i % 2));
edge = ktime_add_us(edge, txbuf[i]);
delay_until(edge);
}
gpiod_set_value(gpio_ir->gpio, 0);
}
static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
uint count)
{
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);
local_irq_disable();
edge = ktime_get();
for (i = 0; i < count; i++) {
if (i % 2) {
// space
edge = ktime_add_us(edge, txbuf[i]);
delay_until(edge);
} 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;
}
}
}
static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
unsigned int count)
{
struct gpio_ir *gpio_ir = dev->priv;
unsigned long flags;
local_irq_save(flags);
if (gpio_ir->carrier)
gpio_ir_tx_modulated(gpio_ir, txbuf, count);
else
gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);
local_irq_restore(flags);
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))
return dev_err_probe(&pdev->dev, PTR_ERR(gpio_ir->gpio),
"Failed to get gpio\n");
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;
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");
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