diff options
Diffstat (limited to 'drivers/media/rc/gpio-ir-tx.c')
| -rw-r--r-- | drivers/media/rc/gpio-ir-tx.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c new file mode 100644 index 0000000000..1a8fea357f --- /dev/null +++ b/drivers/media/rc/gpio-ir-tx.c @@ -0,0 +1,209 @@ +// 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 = 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"); |