[PATCH 0/2] pwm: vt8500: Implement .apply() callback

[PATCH 0/2] pwm: vt8500: Implement .apply() callback

[Uwe Kleine-König]

Hello,

this series implements .apply for the vt8500 pwm driver and fixes a
function name that I stumbled over while doing that.

One thing that could be improved (but probably only with hardware
available which I don't have) is:

 - vt8500_pwm_apply() calls the old callbacks now, it might be possible
   to improve clk handling such that the clk is at most once enabled and
   once disabled.

 - .probe() doesn't handle the PWM already being on.

 - There is no .get_state() callback.

Best regards
Uwe

Uwe Kleine-König (2):
  pwm: vt8500: Implement .apply() callback
  pwm: vt8500: Rename pwm_busy_wait() to make it obviously
    driver-specific

 drivers/pwm/pwm-vt8500.c | 73 +++++++++++++++++++++++++++++++---------
 1 file changed, 58 insertions(+), 15 deletions(-)


base-commit: 8bb7eca972ad531c9b149c0a51ab43a417385813
-- 
2.30.2


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[PATCH 1/2] pwm: vt8500: Implement .apply() callback

[Uwe Kleine-König]

To eventually get rid of all legacy drivers convert this driver to the
modern world implementing .apply(). This just pushes down a slightly
optimized variant of how legacy drivers are handled in the core.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-vt8500.c | 57 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index ea2aa151080a..3203ec1b0d24 100644
--- a/drivers/pwm/pwm-vt8500.c
+++ b/drivers/pwm/pwm-vt8500.c
@@ -70,7 +70,7 @@ static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
 }
 
 static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
-		int duty_ns, int period_ns)
+		u64 duty_ns, u64 period_ns)
 {
 	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
 	unsigned long long c;
@@ -102,8 +102,8 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 	c = (unsigned long long)pv * duty_ns;
-	do_div(c, period_ns);
-	dc = c;
+
+	dc = div64_u64(c, period_ns);
 
 	writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
 	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
@@ -176,11 +176,54 @@ static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
 	return 0;
 }
 
+static int vt8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	int err;
+	bool enabled = pwm->state.enabled;
+
+	if (state->polarity != pwm->state.polarity) {
+		/*
+		 * Changing the polarity of a running PWM is only allowed when
+		 * the PWM driver implements ->apply().
+		 */
+		if (enabled) {
+			vt8500_pwm_disable(chip, pwm);
+
+			enabled = false;
+		}
+
+		err = vt8500_pwm_set_polarity(chip, pwm, state->polarity);
+		if (err)
+			return err;
+	}
+
+	if (!state->enabled) {
+		if (enabled)
+			vt8500_pwm_disable(chip, pwm);
+
+		return 0;
+	}
+
+	/*
+	 * We cannot skip calling ->config even if state->period ==
+	 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
+	 * because we might have exited early in the last call to
+	 * pwm_apply_state because of !state->enabled and so the two values in
+	 * pwm->state might not be configured in hardware.
+	 */
+	err = vt8500_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
+	if (err)
+		return err;
+
+	if (!enabled)
+		err = vt8500_pwm_enable(chip, pwm);
+
+	return err;
+}
+
 static const struct pwm_ops vt8500_pwm_ops = {
-	.enable = vt8500_pwm_enable,
-	.disable = vt8500_pwm_disable,
-	.config = vt8500_pwm_config,
-	.set_polarity = vt8500_pwm_set_polarity,
+	.apply = vt8500_pwm_apply,
 	.owner = THIS_MODULE,
 };
 
-- 
2.30.2


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Re: [PATCH 1/2] pwm: vt8500: Implement .apply() callback

[Thierry Reding]

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On Tue, Nov 02, 2021 at 10:28:03AM +0100, Uwe Kleine-König wrote:
> To eventually get rid of all legacy drivers convert this driver to the
> modern world implementing .apply(). This just pushes down a slightly
> optimized variant of how legacy drivers are handled in the core.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/pwm/pwm-vt8500.c | 57 +++++++++++++++++++++++++++++++++++-----
>  1 file changed, 50 insertions(+), 7 deletions(-)

Applied, thanks.

Thierry

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[-- Attachment #2: Type: text/plain, Size: 176 bytes --]

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[PATCH 2/2] pwm: vt8500: Rename pwm_busy_wait() to make it obviously driver-specific

[Uwe Kleine-König]

The pwm_ prefix suggests that pwm_busy_wait() is a function provided by
the pwm core. Use the otherwise consistently used driver prefix for this
function, too.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/pwm-vt8500.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index 3203ec1b0d24..7170a315535b 100644
--- a/drivers/pwm/pwm-vt8500.c
+++ b/drivers/pwm/pwm-vt8500.c
@@ -56,7 +56,7 @@ struct vt8500_chip {
 #define to_vt8500_chip(chip)	container_of(chip, struct vt8500_chip, chip)
 
 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
-static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
+static inline void vt8500_pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
 {
 	int loops = msecs_to_loops(10);
 	u32 mask = bitmask << (nr << 8);
@@ -106,18 +106,18 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	dc = div64_u64(c, period_ns);
 
 	writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);
 
 	writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);
 
 	writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);
 
 	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 	val |= CTRL_AUTOLOAD;
 	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 
 	clk_disable(vt8500->clk);
 	return 0;
@@ -138,7 +138,7 @@ static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 	val |= CTRL_ENABLE;
 	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 
 	return 0;
 }
@@ -151,7 +151,7 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
 	val &= ~CTRL_ENABLE;
 	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 
 	clk_disable(vt8500->clk);
 }
@@ -171,7 +171,7 @@ static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
 		val &= ~CTRL_INVERT;
 
 	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
-	pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
 
 	return 0;
 }
-- 
2.30.2


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