Merge tag 'pwm/for-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm updates from Thierry Reding:
 "This contains a bunch of cleanups and simplifications across the
  board, as well as a number of small fixes.

  Perhaps the most notable change here is the addition of an API that
  allows PWMs to be used in atomic contexts, which is useful when time-
  critical operations are involved, such as using a PWM to generate IR
  signals.

  Finally, I have decided to step down as PWM subsystem maintainer. Due
  to other responsibilities I have lately not been able to find the time
  that the subsystem deserves and Uwe, who has been helping out a lot
  for the past few years and has many things planned for the future, has
  kindly volunteered to take over. I have no doubt that he will be a
  suitable replacement"

* tag 'pwm/for-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm: (44 commits)
  MAINTAINERS: pwm: Thierry steps down, Uwe takes over
  pwm: linux/pwm.h: fix Excess kernel-doc description warning
  pwm: Add pwm_apply_state() compatibility stub
  pwm: cros-ec: Drop documentation for dropped struct member
  pwm: Drop two unused API functions
  pwm: lpc18xx-sct: Don't modify the cached period of other PWM outputs
  pwm: meson: Simplify using dev_err_probe()
  pwm: stmpe: Silence duplicate error messages
  pwm: Reduce number of pointer dereferences in pwm_device_request()
  pwm: crc: Use consistent variable naming for driver data
  pwm: omap-dmtimer: Drop locking
  dt-bindings: pwm: ti,pwm-omap-dmtimer: Update binding for yaml
  media: pwm-ir-tx: Trigger edges from hrtimer interrupt context
  pwm: bcm2835: Allow PWM driver to be used in atomic context
  pwm: Make it possible to apply PWM changes in atomic context
  pwm: renesas: Remove unused include
  pwm: Replace ENOTSUPP with EOPNOTSUPP
  pwm: Rename pwm_apply_state() to pwm_apply_might_sleep()
  pwm: Stop referencing pwm->chip
  pwm: Update kernel doc for struct pwm_chip
  ...

1 files changed, 80 insertions, 7 deletions

diff --git a/drivers/media/rc/pwm-ir-tx.c b/drivers/media/rc/pwm-ir-tx.c
index c5f37c03af9c..fe368aebbc13 100644
--- a/drivers/media/rc/pwm-ir-tx.c
+++ b/drivers/media/rc/pwm-ir-tx.c
@@ -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[] = {
@@ -49,8 +57,8 @@ 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,
-		     unsigned int count)
+static int pwm_ir_tx_sleep(struct rc_dev *dev, unsigned int *txbuf,
+			   unsigned int count)
 {
 	struct pwm_ir *pwm_ir = dev->priv;
 	struct pwm_device *pwm = pwm_ir->pwm;
@@ -68,7 +76,7 @@ static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
 
 	for (i = 0; i < count; i++) {
 		state.enabled = !(i % 2);
-		pwm_apply_state(pwm, &state);
+		pwm_apply_might_sleep(pwm, &state);
 
 		edge = ktime_add_us(edge, txbuf[i]);
 		delta = ktime_us_delta(edge, ktime_get());
@@ -77,11 +85,67 @@ static int pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
 	}
 
 	state.enabled = false;
-	pwm_apply_state(pwm, &state);
+	pwm_apply_might_sleep(pwm, &state);
 
 	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;