Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1367573 > unrolled thread

[PATCH v5 26/46] pwm: sun4i: implement hardware readout

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH v5 26/46] pwm: sun4i: implement hardware readout Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-30 22:20 +0200
    Re: [PATCH v5 26/46] pwm: sun4i: implement hardware readout Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2016-03-31 10:10 +0200

#1367573 — [PATCH v5 26/46] pwm: sun4i: implement hardware readout

Implement ->get_state() instead of only initializing the polarity in
the probe function.

This implementation also takes care of keeping the PWM clk enabled if at
least one of the PWM exported by the PWM chip is already enabled, which
should prevent glitches.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
 drivers/pwm/pwm-sun4i.c | 74 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 55 insertions(+), 19 deletions(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 03a99a5..34cb296 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -252,11 +252,65 @@ static void sun4i_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	clk_disable_unprepare(sun4i_pwm->clk);
 }
 
+static void sun4i_pwm_get_state(struct pwm_chip *chip,
+				struct pwm_device *pwm,
+				struct pwm_state *pstate)
+{
+	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
+	unsigned int clk_rate = clk_get_rate(sun4i_pwm->clk);
+	int prescaler, prescalerid;
+	int ret;
+	u32 val;
+
+	ret = clk_prepare_enable(sun4i_pwm->clk);
+	if (ret) {
+		dev_err(chip->dev, "Failed to enable PWM clock");
+		return;
+	}
+
+	val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
+	if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
+		pstate->polarity = PWM_POLARITY_INVERSED;
+	else
+		pstate->polarity = PWM_POLARITY_NORMAL;
+
+	if ((val & BIT_CH(PWM_EN, pwm->hwpwm)) &&
+	    (val & BIT_CH(PWM_CLK_GATING, pwm->hwpwm)))
+		pstate->enabled = true;
+	else
+		pstate->enabled = false;
+
+	pstate->period = 0;
+	pstate->duty_cycle = 0;
+	prescalerid = (val >> (PWMCH_OFFSET * pwm->hwpwm)) & PWM_PRESCAL_MASK;
+	prescaler = prescaler_table[prescalerid];
+	if (prescaler) {
+		u64 timens;
+
+		clk_rate /= prescaler;
+
+		val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm));
+
+		timens = ((val >> 16) & PWM_PRD_MASK) + 1;
+		timens *= NSEC_PER_SEC;
+		do_div(timens, clk_rate);
+		pstate->period = timens;
+
+		timens = val & PWM_DTY_MASK;
+		timens *= NSEC_PER_SEC;
+		do_div(timens, clk_rate);
+		pstate->duty_cycle = timens;
+	}
+
+	clk_disable_unprepare(sun4i_pwm->clk);
+}
+
 static const struct pwm_ops sun4i_pwm_ops = {
 	.config = sun4i_pwm_config,
 	.set_polarity = sun4i_pwm_set_polarity,
 	.enable = sun4i_pwm_enable,
 	.disable = sun4i_pwm_disable,
+	.get_state = sun4i_pwm_get_state,
 	.owner = THIS_MODULE,
 };
 
@@ -307,8 +361,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 {
 	struct sun4i_pwm_chip *pwm;
 	struct resource *res;
-	u32 val;
-	int i, ret;
+	int ret;
 	const struct of_device_id *match;
 
 	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
@@ -345,24 +398,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pwm);
 
-	ret = clk_prepare_enable(pwm->clk);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to enable PWM clock\n");
-		goto clk_error;
-	}
-
-	val = sun4i_pwm_readl(pwm, PWM_CTRL_REG);
-	for (i = 0; i < pwm->chip.npwm; i++)
-		if (!(val & BIT_CH(PWM_ACT_STATE, i)))
-			pwm_set_polarity(&pwm->chip.pwms[i],
-					 PWM_POLARITY_INVERSED);
-	clk_disable_unprepare(pwm->clk);
-
 	return 0;
-
-clk_error:
-	pwmchip_remove(&pwm->chip);
-	return ret;
 }
 
 static int sun4i_pwm_remove(struct platform_device *pdev)
-- 
2.5.0

[toc] | [next] | [standalone]

#1367937

On 30/03/2016 at 22:03:49 +0200, Boris Brezillon wrote :
> Implement ->get_state() instead of only initializing the polarity in
> the probe function.
> 
> This implementation also takes care of keeping the PWM clk enabled if at
> least one of the PWM exported by the PWM chip is already enabled, which
> should prevent glitches.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

> ---
>  drivers/pwm/pwm-sun4i.c | 74 ++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 55 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index 03a99a5..34cb296 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -252,11 +252,65 @@ static void sun4i_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  	clk_disable_unprepare(sun4i_pwm->clk);
>  }
>  
> +static void sun4i_pwm_get_state(struct pwm_chip *chip,
> +				struct pwm_device *pwm,
> +				struct pwm_state *pstate)
> +{
> +	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
> +	unsigned int clk_rate = clk_get_rate(sun4i_pwm->clk);
> +	int prescaler, prescalerid;
> +	int ret;
> +	u32 val;
> +
> +	ret = clk_prepare_enable(sun4i_pwm->clk);
> +	if (ret) {
> +		dev_err(chip->dev, "Failed to enable PWM clock");
> +		return;
> +	}
> +
> +	val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
> +	if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
> +		pstate->polarity = PWM_POLARITY_INVERSED;
> +	else
> +		pstate->polarity = PWM_POLARITY_NORMAL;
> +
> +	if ((val & BIT_CH(PWM_EN, pwm->hwpwm)) &&
> +	    (val & BIT_CH(PWM_CLK_GATING, pwm->hwpwm)))
> +		pstate->enabled = true;
> +	else
> +		pstate->enabled = false;
> +
> +	pstate->period = 0;
> +	pstate->duty_cycle = 0;
> +	prescalerid = (val >> (PWMCH_OFFSET * pwm->hwpwm)) & PWM_PRESCAL_MASK;
> +	prescaler = prescaler_table[prescalerid];
> +	if (prescaler) {
> +		u64 timens;
> +
> +		clk_rate /= prescaler;
> +
> +		val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm));
> +
> +		timens = ((val >> 16) & PWM_PRD_MASK) + 1;
> +		timens *= NSEC_PER_SEC;
> +		do_div(timens, clk_rate);
> +		pstate->period = timens;
> +
> +		timens = val & PWM_DTY_MASK;
> +		timens *= NSEC_PER_SEC;
> +		do_div(timens, clk_rate);
> +		pstate->duty_cycle = timens;
> +	}
> +
> +	clk_disable_unprepare(sun4i_pwm->clk);
> +}
> +
>  static const struct pwm_ops sun4i_pwm_ops = {
>  	.config = sun4i_pwm_config,
>  	.set_polarity = sun4i_pwm_set_polarity,
>  	.enable = sun4i_pwm_enable,
>  	.disable = sun4i_pwm_disable,
> +	.get_state = sun4i_pwm_get_state,
>  	.owner = THIS_MODULE,
>  };
>  
> @@ -307,8 +361,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  {
>  	struct sun4i_pwm_chip *pwm;
>  	struct resource *res;
> -	u32 val;
> -	int i, ret;
> +	int ret;
>  	const struct of_device_id *match;
>  
>  	match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
> @@ -345,24 +398,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, pwm);
>  
> -	ret = clk_prepare_enable(pwm->clk);
> -	if (ret) {
> -		dev_err(&pdev->dev, "failed to enable PWM clock\n");
> -		goto clk_error;
> -	}
> -
> -	val = sun4i_pwm_readl(pwm, PWM_CTRL_REG);
> -	for (i = 0; i < pwm->chip.npwm; i++)
> -		if (!(val & BIT_CH(PWM_ACT_STATE, i)))
> -			pwm_set_polarity(&pwm->chip.pwms[i],
> -					 PWM_POLARITY_INVERSED);
> -	clk_disable_unprepare(pwm->clk);
> -
>  	return 0;
> -
> -clk_error:
> -	pwmchip_remove(&pwm->chip);
> -	return ret;
>  }
>  
>  static int sun4i_pwm_remove(struct platform_device *pdev)
> -- 
> 2.5.0
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web