alistair23-linux/drivers/media/rc/ir-rx51.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2008 Nokia Corporation
 *
 *  Based on lirc_serial.c
 */
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/wait.h>
#include <linux/pwm.h>
#include <linux/of.h>
#include <linux/hrtimer.h>

#include <media/rc-core.h>

#define WBUF_LEN 256

struct ir_rx51 {
	struct rc_dev *rcdev;
	struct pwm_device *pwm;
	struct hrtimer timer;
	struct device	     *dev;
	wait_queue_head_t     wqueue;

	unsigned int	freq;		/* carrier frequency */
	unsigned int	duty_cycle;	/* carrier duty cycle */
	int		wbuf[WBUF_LEN];
	int		wbuf_index;
	unsigned long	device_is_open;
};

static inline void ir_rx51_on(struct ir_rx51 *ir_rx51)
{
	pwm_enable(ir_rx51->pwm);
}

static inline void ir_rx51_off(struct ir_rx51 *ir_rx51)
{
	pwm_disable(ir_rx51->pwm);
}

static int init_timing_params(struct ir_rx51 *ir_rx51)
{
	struct pwm_device *pwm = ir_rx51->pwm;
	int duty, period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, ir_rx51->freq);

	duty = DIV_ROUND_CLOSEST(ir_rx51->duty_cycle * period, 100);

	pwm_config(pwm, duty, period);

	return 0;
}

static enum hrtimer_restart ir_rx51_timer_cb(struct hrtimer *timer)
{
	struct ir_rx51 *ir_rx51 = container_of(timer, struct ir_rx51, timer);
	ktime_t now;

	if (ir_rx51->wbuf_index < 0) {
		dev_err_ratelimited(ir_rx51->dev,
				    "BUG wbuf_index has value of %i\n",
				    ir_rx51->wbuf_index);
		goto end;
	}

	/*
	 * If we happen to hit an odd latency spike, loop through the
	 * pulses until we catch up.
	 */
	do {
		u64 ns;

		if (ir_rx51->wbuf_index >= WBUF_LEN)
			goto end;
		if (ir_rx51->wbuf[ir_rx51->wbuf_index] == -1)
			goto end;

		if (ir_rx51->wbuf_index % 2)
			ir_rx51_off(ir_rx51);
		else
			ir_rx51_on(ir_rx51);

		ns = US_TO_NS(ir_rx51->wbuf[ir_rx51->wbuf_index]);
		hrtimer_add_expires_ns(timer, ns);

		ir_rx51->wbuf_index++;

		now = timer->base->get_time();

	} while (hrtimer_get_expires_tv64(timer) < now);

	return HRTIMER_RESTART;
end:
	/* Stop TX here */
	ir_rx51_off(ir_rx51);
	ir_rx51->wbuf_index = -1;

	wake_up_interruptible(&ir_rx51->wqueue);

	return HRTIMER_NORESTART;
}

static int ir_rx51_tx(struct rc_dev *dev, unsigned int *buffer,
		      unsigned int count)
{
	struct ir_rx51 *ir_rx51 = dev->priv;

	if (count > WBUF_LEN)
		return -EINVAL;

	memcpy(ir_rx51->wbuf, buffer, count * sizeof(unsigned int));

	/* Wait any pending transfers to finish */
	wait_event_interruptible(ir_rx51->wqueue, ir_rx51->wbuf_index < 0);

	init_timing_params(ir_rx51);
	if (count < WBUF_LEN)
		ir_rx51->wbuf[count] = -1; /* Insert termination mark */

	/*
	 * REVISIT: Adjust latency requirements so the device doesn't go in too
	 * deep sleep states with pm_qos_add_request().
	 */

	ir_rx51_on(ir_rx51);
	ir_rx51->wbuf_index = 1;
	hrtimer_start(&ir_rx51->timer,
		      ns_to_ktime(US_TO_NS(ir_rx51->wbuf[0])),
		      HRTIMER_MODE_REL);
	/*
	 * Don't return back to the userspace until the transfer has
	 * finished
	 */
	wait_event_interruptible(ir_rx51->wqueue, ir_rx51->wbuf_index < 0);

	/* REVISIT: Remove pm_qos constraint, we can sleep again */

	return count;
}

static int ir_rx51_open(struct rc_dev *dev)
{
	struct ir_rx51 *ir_rx51 = dev->priv;

	if (test_and_set_bit(1, &ir_rx51->device_is_open))
		return -EBUSY;

	ir_rx51->pwm = pwm_get(ir_rx51->dev, NULL);
	if (IS_ERR(ir_rx51->pwm)) {
		int res = PTR_ERR(ir_rx51->pwm);

		dev_err(ir_rx51->dev, "pwm_get failed: %d\n", res);
		return res;
	}

	return 0;
}

static void ir_rx51_release(struct rc_dev *dev)
{
	struct ir_rx51 *ir_rx51 = dev->priv;

	hrtimer_cancel(&ir_rx51->timer);
	ir_rx51_off(ir_rx51);
	pwm_put(ir_rx51->pwm);

	clear_bit(1, &ir_rx51->device_is_open);
}

static struct ir_rx51 ir_rx51 = {
	.duty_cycle	= 50,
	.wbuf_index	= -1,
};

static int ir_rx51_set_duty_cycle(struct rc_dev *dev, u32 duty)
{
	struct ir_rx51 *ir_rx51 = dev->priv;

	ir_rx51->duty_cycle = duty;

	return 0;
}

static int ir_rx51_set_tx_carrier(struct rc_dev *dev, u32 carrier)
{
	struct ir_rx51 *ir_rx51 = dev->priv;

	if (carrier > 500000 || carrier < 20000)
		return -EINVAL;

	ir_rx51->freq = carrier;

	return 0;
}

#ifdef CONFIG_PM

static int ir_rx51_suspend(struct platform_device *dev, pm_message_t state)
{
	/*
	 * In case the device is still open, do not suspend. Normally
	 * this should not be a problem as lircd only keeps the device
	 * open only for short periods of time. We also don't want to
	 * get involved with race conditions that might happen if we
	 * were in a middle of a transmit. Thus, we defer any suspend
	 * actions until transmit has completed.
	 */
	if (test_and_set_bit(1, &ir_rx51.device_is_open))
		return -EAGAIN;

	clear_bit(1, &ir_rx51.device_is_open);

	return 0;
}

static int ir_rx51_resume(struct platform_device *dev)
{
	return 0;
}

#else

#define ir_rx51_suspend	NULL
#define ir_rx51_resume	NULL

#endif /* CONFIG_PM */

static int ir_rx51_probe(struct platform_device *dev)
{
	struct pwm_device *pwm;
	struct rc_dev *rcdev;

	pwm = pwm_get(&dev->dev, NULL);
	if (IS_ERR(pwm)) {
		int err = PTR_ERR(pwm);

		if (err != -EPROBE_DEFER)
			dev_err(&dev->dev, "pwm_get failed: %d\n", err);
		return err;
	}

	/* Use default, in case userspace does not set the carrier */
	ir_rx51.freq = DIV_ROUND_CLOSEST(pwm_get_period(pwm), NSEC_PER_SEC);
	pwm_put(pwm);

	hrtimer_init(&ir_rx51.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	ir_rx51.timer.function = ir_rx51_timer_cb;

	ir_rx51.dev = &dev->dev;

	rcdev = devm_rc_allocate_device(&dev->dev, RC_DRIVER_IR_RAW_TX);
	if (!rcdev)
		return -ENOMEM;

	rcdev->priv = &ir_rx51;
	rcdev->open = ir_rx51_open;
	rcdev->close = ir_rx51_release;
	rcdev->tx_ir = ir_rx51_tx;
	rcdev->s_tx_duty_cycle = ir_rx51_set_duty_cycle;
	rcdev->s_tx_carrier = ir_rx51_set_tx_carrier;
	rcdev->driver_name = KBUILD_MODNAME;

	ir_rx51.rcdev = rcdev;

	return devm_rc_register_device(&dev->dev, ir_rx51.rcdev);
}

static int ir_rx51_remove(struct platform_device *dev)
{
	return 0;
}

static const struct of_device_id ir_rx51_match[] = {
	{
		.compatible = "nokia,n900-ir",
	},
	{},
};
MODULE_DEVICE_TABLE(of, ir_rx51_match);

static struct platform_driver ir_rx51_platform_driver = {
	.probe		= ir_rx51_probe,
	.remove		= ir_rx51_remove,
	.suspend	= ir_rx51_suspend,
	.resume		= ir_rx51_resume,
	.driver		= {
		.name	= KBUILD_MODNAME,
		.of_match_table = of_match_ptr(ir_rx51_match),
	},
};
module_platform_driver(ir_rx51_platform_driver);

MODULE_DESCRIPTION("IR TX driver for Nokia RX51");
MODULE_AUTHOR("Nokia Corporation");
MODULE_LICENSE("GPL");