Commit 363d0e56 authored by Sean Young's avatar Sean Young Committed by Thierry Reding
Browse files

media: pwm-ir-tx: Trigger edges from hrtimer interrupt context 



This makes the generated IR much more precise. Before this change, the
driver is unreliable and many users opted to use gpio-ir-tx instead.

Signed-off-by: default avatarSean Young <sean@mess.org>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent fcc76072

drivers/media/rc/pwm-ir-tx.c

+78 −5
Original line number Diff line number Diff line
@@ -10,6 +10,8 @@ 
#include <linux/slab.h>

#include <linux/of.h>

#include <linux/platform_device.h>

#include <linux/hrtimer.h>

#include <linux/completion.h>

#include <media/rc-core.h>



#define DRIVER_NAME	"pwm-ir-tx"
@@ -17,8 +19,14 @@ 


struct pwm_ir {

	struct pwm_device *pwm;

	unsigned int carrier;

	unsigned int duty_cycle;

	struct hrtimer timer;

	struct completion tx_done;

	struct pwm_state *state;

	u32 carrier;

	u32 duty_cycle;

	const unsigned int *txbuf;

	unsigned int txbuf_len;

	unsigned int txbuf_index;

};



static const struct of_device_id pwm_ir_of_match[] = {
@@ -49,7 +57,7 @@ static int pwm_ir_set_carrier(struct rc_dev *dev, u32 carrier) 
	return 0;

}



static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,

static int pwm_ir_tx_sleep(struct rc_dev *dev, unsigned int *txbuf,

			   unsigned int count)

{

	struct pwm_ir *pwm_ir = dev->priv;
@@ -82,6 +90,62 @@ static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf, 
	return count;

}



static int pwm_ir_tx_atomic(struct rc_dev *dev, unsigned int *txbuf,

			    unsigned int count)

{

	struct pwm_ir *pwm_ir = dev->priv;

	struct pwm_device *pwm = pwm_ir->pwm;

	struct pwm_state state;



	pwm_init_state(pwm, &state);



	state.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, pwm_ir->carrier);

	pwm_set_relative_duty_cycle(&state, pwm_ir->duty_cycle, 100);



	pwm_ir->txbuf = txbuf;

	pwm_ir->txbuf_len = count;

	pwm_ir->txbuf_index = 0;

	pwm_ir->state = &state;



	hrtimer_start(&pwm_ir->timer, 0, HRTIMER_MODE_REL);



	wait_for_completion(&pwm_ir->tx_done);



	return count;

}



static enum hrtimer_restart pwm_ir_timer(struct hrtimer *timer)

{

	struct pwm_ir *pwm_ir = container_of(timer, struct pwm_ir, timer);

	ktime_t now;



	/*

	 * If we happen to hit an odd latency spike, loop through the

	 * pulses until we catch up.

	 */

	do {

		u64 ns;



		pwm_ir->state->enabled = !(pwm_ir->txbuf_index % 2);

		pwm_apply_atomic(pwm_ir->pwm, pwm_ir->state);



		if (pwm_ir->txbuf_index >= pwm_ir->txbuf_len) {

			complete(&pwm_ir->tx_done);



			return HRTIMER_NORESTART;

		}



		ns = US_TO_NS(pwm_ir->txbuf[pwm_ir->txbuf_index]);

		hrtimer_add_expires_ns(timer, ns);



		pwm_ir->txbuf_index++;



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

	} while (hrtimer_get_expires_tv64(timer) < now);



	return HRTIMER_RESTART;

}



static int pwm_ir_probe(struct platform_device *pdev)

{

	struct pwm_ir *pwm_ir;
@@ -103,10 +167,19 @@ static int pwm_ir_probe(struct platform_device *pdev) 
	if (!rcdev)

		return -ENOMEM;



	if (pwm_might_sleep(pwm_ir->pwm)) {

		dev_info(&pdev->dev, "TX will not be accurate as PWM device might sleep\n");

		rcdev->tx_ir = pwm_ir_tx_sleep;

	} else {

		init_completion(&pwm_ir->tx_done);

		hrtimer_init(&pwm_ir->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

		pwm_ir->timer.function = pwm_ir_timer;

		rcdev->tx_ir = pwm_ir_tx_atomic;

	}



	rcdev->priv = pwm_ir;

	rcdev->driver_name = DRIVER_NAME;

	rcdev->device_name = DEVICE_NAME;

	rcdev->tx_ir = pwm_ir_tx;

	rcdev->s_tx_duty_cycle = pwm_ir_set_duty_cycle;

	rcdev->s_tx_carrier = pwm_ir_set_carrier;