[v5] pwm: atmel: Enable clk when pwm already enabled in bootloader

[PATCH v5] pwm: atmel: Enable clk when pwm already enabled in bootloader

Posted by Guiting Shen 2 years, 6 months ago

The driver would never call clk_enable() if the PWM channel was already
enabled in bootloader which lead to dump the warning message "the PWM
clock already disabled" when turning off the PWM channel.

Add atmel_pwm_enable_clk_if_on() in probe function to enable clock if
the PWM channel was already enabled in bootloader.

Signed-off-by: Guiting Shen <aarongt.shen@gmail.com>
---
 drivers/pwm/pwm-atmel.c | 50 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index cdbc23649032..4dd6e1319343 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -36,7 +36,7 @@
 #define PWM_SR			0x0C
 #define PWM_ISR			0x1C
 /* Bit field in SR */
-#define PWM_SR_ALL_CH_ON	0x0F
+#define PWM_SR_ALL_CH_MASK	0x0F
 
 /* The following register is PWM channel related registers */
 #define PWM_CH_REG_OFFSET	0x200
@@ -464,6 +464,45 @@ static const struct of_device_id atmel_pwm_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
 
+static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm, bool on)
+{
+	unsigned int i, cnt = 0;
+	int ret = 0;
+	u32 sr;
+
+	sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
+	if (!sr)
+		return 0;
+
+	for (i = 0; i < atmel_pwm->chip.npwm; i++) {
+		if (sr & (1 << i))
+			cnt++;
+	}
+
+	if (!on)
+		goto disable_clk;
+
+	for (i = 0; i < cnt; i++) {
+		ret = clk_enable(atmel_pwm->clk);
+		if (ret) {
+			dev_err(atmel_pwm->chip.dev,
+				"failed to enable clock for pwm #%d: %pe\n",
+							i, ERR_PTR(ret));
+
+			cnt = i;
+			goto disable_clk;
+		}
+	}
+
+	return 0;
+
+disable_clk:
+	while (cnt--)
+		clk_disable(atmel_pwm->clk);
+
+	return ret;
+}
+
 static int atmel_pwm_probe(struct platform_device *pdev)
 {
 	struct atmel_pwm_chip *atmel_pwm;
@@ -496,16 +535,23 @@ static int atmel_pwm_probe(struct platform_device *pdev)
 	atmel_pwm->chip.ops = &atmel_pwm_ops;
 	atmel_pwm->chip.npwm = 4;
 
+	ret = atmel_pwm_enable_clk_if_on(atmel_pwm, true);
+	if (ret < 0)
+		goto unprepare_clk;
+
 	ret = pwmchip_add(&atmel_pwm->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret);
-		goto unprepare_clk;
+		goto disable_clk;
 	}
 
 	platform_set_drvdata(pdev, atmel_pwm);
 
 	return ret;
 
+disable_clk:
+	atmel_pwm_enable_clk_if_on(atmel_pwm, false);
+
 unprepare_clk:
 	clk_unprepare(atmel_pwm->clk);
 	return ret;
-- 
2.25.1

Re: [PATCH v5] pwm: atmel: Enable clk when pwm already enabled in bootloader

Posted by Uwe Kleine-König 2 years, 6 months ago

On Sat, Jul 15, 2023 at 10:36:53AM +0800, Guiting Shen wrote:
> The driver would never call clk_enable() if the PWM channel was already
> enabled in bootloader which lead to dump the warning message "the PWM
> clock already disabled" when turning off the PWM channel.
> 
> Add atmel_pwm_enable_clk_if_on() in probe function to enable clock if
> the PWM channel was already enabled in bootloader.
> 
> Signed-off-by: Guiting Shen <aarongt.shen@gmail.com>
> ---
>  drivers/pwm/pwm-atmel.c | 50 +++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 48 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
> index cdbc23649032..4dd6e1319343 100644
> --- a/drivers/pwm/pwm-atmel.c
> +++ b/drivers/pwm/pwm-atmel.c
> @@ -36,7 +36,7 @@
>  #define PWM_SR			0x0C
>  #define PWM_ISR			0x1C
>  /* Bit field in SR */
> -#define PWM_SR_ALL_CH_ON	0x0F
> +#define PWM_SR_ALL_CH_MASK	0x0F
>  
>  /* The following register is PWM channel related registers */
>  #define PWM_CH_REG_OFFSET	0x200
> @@ -464,6 +464,45 @@ static const struct of_device_id atmel_pwm_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
>  
> +static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm, bool on)
> +{
> +	unsigned int i, cnt = 0;
> +	int ret = 0;
> +	u32 sr;
> +
> +	sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
> +	if (!sr)
> +		return 0;
> +
> +	for (i = 0; i < atmel_pwm->chip.npwm; i++) {
> +		if (sr & (1 << i))
> +			cnt++;
> +	}

If it's just about counting the set bits, there is the function
bitmap_weight().

> +	if (!on)
> +		goto disable_clk;
> +
> +	for (i = 0; i < cnt; i++) {
> +		ret = clk_enable(atmel_pwm->clk);
> +		if (ret) {
> +			dev_err(atmel_pwm->chip.dev,
> +				"failed to enable clock for pwm #%d: %pe\n",
> +							i, ERR_PTR(ret));

The output is bogus here. If SR is say 0xc, and the second enable
fails, it's about pwm #3, but then i is 1.

> +			cnt = i;
> +			goto disable_clk;
> +		}
> +	}
> +
> +	return 0;
> +
> +disable_clk:
> +	while (cnt--)
> +		clk_disable(atmel_pwm->clk);
> +
> +	return ret;
> +}
> +
>  static int atmel_pwm_probe(struct platform_device *pdev)
>  {
>  	struct atmel_pwm_chip *atmel_pwm;

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

Re: [PATCH v5] pwm: atmel: Enable clk when pwm already enabled in bootloader

Posted by Guiting Shen 2 years, 6 months ago


On Sat,Jul 15,2023 at 20:12:53PM GMT+8, Uwe Kleine-König wrote:
> On Sat, Jul 15, 2023 at 10:36:53AM +0800, Guiting Shen wrote:
>> The driver would never call clk_enable() if the PWM channel was already
>> enabled in bootloader which lead to dump the warning message "the PWM
>> clock already disabled" when turning off the PWM channel.
>>
>> Add atmel_pwm_enable_clk_if_on() in probe function to enable clock if
>> the PWM channel was already enabled in bootloader.
>>
>> Signed-off-by: Guiting Shen <aarongt.shen@gmail.com>
>> ---
>>   drivers/pwm/pwm-atmel.c | 50 +++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 48 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
>> index cdbc23649032..4dd6e1319343 100644
>> --- a/drivers/pwm/pwm-atmel.c
>> +++ b/drivers/pwm/pwm-atmel.c
>> @@ -36,7 +36,7 @@
>>   #define PWM_SR			0x0C
>>   #define PWM_ISR			0x1C
>>   /* Bit field in SR */
>> -#define PWM_SR_ALL_CH_ON	0x0F
>> +#define PWM_SR_ALL_CH_MASK	0x0F
>>   
>>   /* The following register is PWM channel related registers */
>>   #define PWM_CH_REG_OFFSET	0x200
>> @@ -464,6 +464,45 @@ static const struct of_device_id atmel_pwm_dt_ids[] = {
>>   };
>>   MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
>>   
>> +static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm, bool on)
>> +{
>> +	unsigned int i, cnt = 0;
>> +	int ret = 0;
>> +	u32 sr;
>> +
>> +	sr = atmel_pwm_readl(atmel_pwm, PWM_SR) & PWM_SR_ALL_CH_MASK;
>> +	if (!sr)
>> +		return 0;
>> +
>> +	for (i = 0; i < atmel_pwm->chip.npwm; i++) {
>> +		if (sr & (1 << i))
>> +			cnt++;
>> +	}
> 
> If it's just about counting the set bits, there is the function
> bitmap_weight().

Got it, Thank you.


>> +	if (!on)
>> +		goto disable_clk;
>> +
>> +	for (i = 0; i < cnt; i++) {
>> +		ret = clk_enable(atmel_pwm->clk);
>> +		if (ret) {
>> +			dev_err(atmel_pwm->chip.dev,
>> +				"failed to enable clock for pwm #%d: %pe\n",
>> +							i, ERR_PTR(ret));
> 
> The output is bogus here. If SR is say 0xc, and the second enable
> fails, it's about pwm #3, but then i is 1.

I would just output the error clock message like this to fix it:
	dev_err(atmel_pwm->chip.dev,
		"failed to enable clock for pwm %pe\n", ERR_PTR(ret));


>> +			cnt = i;
>> +			goto disable_clk;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +
>> +disable_clk:
>> +	while (cnt--)
>> +		clk_disable(atmel_pwm->clk);
>> +
>> +	return ret;
>> +}
>> +
>>   static int atmel_pwm_probe(struct platform_device *pdev)
>>   {
>>   	struct atmel_pwm_chip *atmel_pwm;
> 
> Best regards
> Uwe
> 

-- 
Best regards,
Guiting Shen