[v2,2/7] pwm: sun4i: Add an optional probe for reset line
diff mbox series

Message ID 20191103203334.10539-3-peron.clem@gmail.com
State New
Headers show
Series
  • Add support for H6 PWM
Related show

Commit Message

Clément Péron Nov. 3, 2019, 8:33 p.m. UTC
From: Jernej Skrabec <jernej.skrabec@siol.net>

H6 PWM core needs deasserted reset line in order to work.

Add an optional probe for it.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
---
 drivers/pwm/pwm-sun4i.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

Comments

Uwe Kleine-König Nov. 4, 2019, 8:11 a.m. UTC | #1
Hello,

adding Philipp Zabel (= reset controller maintainer) to Cc: and so I'm
not stripping the uncommented parts of the patch.

On Sun, Nov 03, 2019 at 09:33:29PM +0100, Clément Péron wrote:
> From: Jernej Skrabec <jernej.skrabec@siol.net>
> 
> H6 PWM core needs deasserted reset line in order to work.
> 
> Add an optional probe for it.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> Signed-off-by: Clément Péron <peron.clem@gmail.com>
> ---
>  drivers/pwm/pwm-sun4i.c | 32 ++++++++++++++++++++++++++++++--
>  1 file changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index 6f5840a1a82d..d194b8ebdb00 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -16,6 +16,7 @@
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/pwm.h>
> +#include <linux/reset.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <linux/time.h>
> @@ -78,6 +79,7 @@ struct sun4i_pwm_data {
>  struct sun4i_pwm_chip {
>  	struct pwm_chip chip;
>  	struct clk *clk;
> +	struct reset_control *rst;
>  	void __iomem *base;
>  	spinlock_t ctrl_lock;
>  	const struct sun4i_pwm_data *data;
> @@ -365,6 +367,20 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  	if (IS_ERR(pwm->clk))
>  		return PTR_ERR(pwm->clk);
>  
> +	pwm->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
> +	if (IS_ERR(pwm->rst)) {
> +		if (PTR_ERR(pwm->rst) == -EPROBE_DEFER)
> +			return PTR_ERR(pwm->rst);
> +		dev_info(&pdev->dev, "no reset control found\n");

I would degrade this to a dev_dbg. Otherwise this spams the log for all
unaffected machines. devm_reset_control_get_optional() is defined in a
section that has a comment "These inline function calls will be removed
once all consumers have been moved over to the new explicit API.", so I
guess you want devm_reset_control_get_optional_exclusive or even
devm_reset_control_get_optional_shared here.

@Philipp: maybe a check in checkpatch that warns about introduction of
such new instances would be good?!

> +	}
> +
> +	/* Deassert reset */
> +	ret = reset_control_deassert(pwm->rst);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Cannot deassert reset control\n");
> +		return ret;
> +	}
> +
>  	pwm->chip.dev = &pdev->dev;
>  	pwm->chip.ops = &sun4i_pwm_ops;
>  	pwm->chip.base = -1;
> @@ -377,19 +393,31 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
>  	ret = pwmchip_add(&pwm->chip);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
> -		return ret;
> +		goto err_pwm_add;
>  	}
>  
>  	platform_set_drvdata(pdev, pwm);
>  
>  	return 0;
> +
> +err_pwm_add:
> +	reset_control_assert(pwm->rst);
> +
> +	return ret;
>  }
>  
>  static int sun4i_pwm_remove(struct platform_device *pdev)
>  {
>  	struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
> +	int ret;
> +
> +	ret = pwmchip_remove(&pwm->chip);
> +	if (ret)
> +		return ret;
> +
> +	reset_control_assert(pwm->rst);
>  
> -	return pwmchip_remove(&pwm->chip);
> +	return 0;
>  }
>  
>  static struct platform_driver sun4i_pwm_driver = {

Best regards
Uwe
Clément Péron Nov. 4, 2019, 5:50 p.m. UTC | #2
On Mon, 4 Nov 2019 at 09:11, Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
>
> Hello,
>
> adding Philipp Zabel (= reset controller maintainer) to Cc: and so I'm
> not stripping the uncommented parts of the patch.
>
> On Sun, Nov 03, 2019 at 09:33:29PM +0100, Clément Péron wrote:
> > From: Jernej Skrabec <jernej.skrabec@siol.net>
> >
> > H6 PWM core needs deasserted reset line in order to work.
> >
> > Add an optional probe for it.
> >
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > Signed-off-by: Clément Péron <peron.clem@gmail.com>
> > ---
> >  drivers/pwm/pwm-sun4i.c | 32 ++++++++++++++++++++++++++++++--
> >  1 file changed, 30 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> > index 6f5840a1a82d..d194b8ebdb00 100644
> > --- a/drivers/pwm/pwm-sun4i.c
> > +++ b/drivers/pwm/pwm-sun4i.c
> > @@ -16,6 +16,7 @@
> >  #include <linux/of_device.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/pwm.h>
> > +#include <linux/reset.h>
> >  #include <linux/slab.h>
> >  #include <linux/spinlock.h>
> >  #include <linux/time.h>
> > @@ -78,6 +79,7 @@ struct sun4i_pwm_data {
> >  struct sun4i_pwm_chip {
> >       struct pwm_chip chip;
> >       struct clk *clk;
> > +     struct reset_control *rst;
> >       void __iomem *base;
> >       spinlock_t ctrl_lock;
> >       const struct sun4i_pwm_data *data;
> > @@ -365,6 +367,20 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
> >       if (IS_ERR(pwm->clk))
> >               return PTR_ERR(pwm->clk);
> >
> > +     pwm->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
> > +     if (IS_ERR(pwm->rst)) {
> > +             if (PTR_ERR(pwm->rst) == -EPROBE_DEFER)
> > +                     return PTR_ERR(pwm->rst);
> > +             dev_info(&pdev->dev, "no reset control found\n");
>
> I would degrade this to a dev_dbg. Otherwise this spams the log for all
> unaffected machines. devm_reset_control_get_optional() is defined in a
> section that has a comment "These inline function calls will be removed
> once all consumers have been moved over to the new explicit API.", so I
> guess you want devm_reset_control_get_optional_exclusive or even
> devm_reset_control_get_optional_shared here.
Thanks for pointing this, I will change it.

>
> @Philipp: maybe a check in checkpatch that warns about introduction of
> such new instances would be good?!
>
> > +     }
> > +
> > +     /* Deassert reset */
> > +     ret = reset_control_deassert(pwm->rst);
> > +     if (ret) {
> > +             dev_err(&pdev->dev, "Cannot deassert reset control\n");
> > +             return ret;
> > +     }
> > +
> >       pwm->chip.dev = &pdev->dev;
> >       pwm->chip.ops = &sun4i_pwm_ops;
> >       pwm->chip.base = -1;
> > @@ -377,19 +393,31 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
> >       ret = pwmchip_add(&pwm->chip);
> >       if (ret < 0) {
> >               dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
> > -             return ret;
> > +             goto err_pwm_add;
> >       }
> >
> >       platform_set_drvdata(pdev, pwm);
> >
> >       return 0;
> > +
> > +err_pwm_add:
> > +     reset_control_assert(pwm->rst);
> > +
> > +     return ret;
> >  }
> >
> >  static int sun4i_pwm_remove(struct platform_device *pdev)
> >  {
> >       struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
> > +     int ret;
> > +
> > +     ret = pwmchip_remove(&pwm->chip);
> > +     if (ret)
> > +             return ret;
> > +
> > +     reset_control_assert(pwm->rst);
> >
> > -     return pwmchip_remove(&pwm->chip);
> > +     return 0;
> >  }
> >
> >  static struct platform_driver sun4i_pwm_driver = {
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Philipp Zabel Nov. 5, 2019, 7:01 a.m. UTC | #3
On Mon, Nov 04, 2019 at 09:11:57AM +0100, Uwe Kleine-König wrote:
> Hello,
> 
> adding Philipp Zabel (= reset controller maintainer) to Cc: and so I'm
> not stripping the uncommented parts of the patch.
> 
> On Sun, Nov 03, 2019 at 09:33:29PM +0100, Clément Péron wrote:
> > From: Jernej Skrabec <jernej.skrabec@siol.net>
> > 
> > H6 PWM core needs deasserted reset line in order to work.
> > 
> > Add an optional probe for it.
> > 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > Signed-off-by: Clément Péron <peron.clem@gmail.com>
> > ---
> >  drivers/pwm/pwm-sun4i.c | 32 ++++++++++++++++++++++++++++++--
> >  1 file changed, 30 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> > index 6f5840a1a82d..d194b8ebdb00 100644
> > --- a/drivers/pwm/pwm-sun4i.c
> > +++ b/drivers/pwm/pwm-sun4i.c
> > @@ -16,6 +16,7 @@
> >  #include <linux/of_device.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/pwm.h>
> > +#include <linux/reset.h>
> >  #include <linux/slab.h>
> >  #include <linux/spinlock.h>
> >  #include <linux/time.h>
> > @@ -78,6 +79,7 @@ struct sun4i_pwm_data {
> >  struct sun4i_pwm_chip {
> >  	struct pwm_chip chip;
> >  	struct clk *clk;
> > +	struct reset_control *rst;
> >  	void __iomem *base;
> >  	spinlock_t ctrl_lock;
> >  	const struct sun4i_pwm_data *data;
> > @@ -365,6 +367,20 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
> >  	if (IS_ERR(pwm->clk))
> >  		return PTR_ERR(pwm->clk);
> >  
> > +	pwm->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
> > +	if (IS_ERR(pwm->rst)) {
> > +		if (PTR_ERR(pwm->rst) == -EPROBE_DEFER)
> > +			return PTR_ERR(pwm->rst);
> > +		dev_info(&pdev->dev, "no reset control found\n");
> 
> I would degrade this to a dev_dbg. Otherwise this spams the log for all
> unaffected machines.

The _optional variants return NULL if the reset is not specified in the
device tree, so this is not "no reset control found", but a real error
that should be returned.

> devm_reset_control_get_optional() is defined in a section that has a
> comment "These inline function calls will be removed once all
> consumers have been moved over to the new explicit API.", so I guess
> you want devm_reset_control_get_optional_exclusive or even
> devm_reset_control_get_optional_shared here.

Correct. If this driver deasserts in probe() and asserts the reset in
remove(), this can use the refcounting _shared variant.

> @Philipp: maybe a check in checkpatch that warns about introduction of
> such new instances would be good?!

Yes, that would be helpful.

regards
Philipp
Clément Péron Nov. 5, 2019, 1:03 p.m. UTC | #4
Hi Philipp,

On Tue, 5 Nov 2019 at 08:01, Philipp Zabel <pza@pengutronix.de> wrote:
>
> On Mon, Nov 04, 2019 at 09:11:57AM +0100, Uwe Kleine-König wrote:
> > Hello,
> >
> > adding Philipp Zabel (= reset controller maintainer) to Cc: and so I'm
> > not stripping the uncommented parts of the patch.
> >
> > On Sun, Nov 03, 2019 at 09:33:29PM +0100, Clément Péron wrote:
> > > From: Jernej Skrabec <jernej.skrabec@siol.net>
> > >
> > > H6 PWM core needs deasserted reset line in order to work.
> > >
> > > Add an optional probe for it.
> > >
> > > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > > Signed-off-by: Clément Péron <peron.clem@gmail.com>
> > > ---
> > >  drivers/pwm/pwm-sun4i.c | 32 ++++++++++++++++++++++++++++++--
> > >  1 file changed, 30 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> > > index 6f5840a1a82d..d194b8ebdb00 100644
> > > --- a/drivers/pwm/pwm-sun4i.c
> > > +++ b/drivers/pwm/pwm-sun4i.c
> > > @@ -16,6 +16,7 @@
> > >  #include <linux/of_device.h>
> > >  #include <linux/platform_device.h>
> > >  #include <linux/pwm.h>
> > > +#include <linux/reset.h>
> > >  #include <linux/slab.h>
> > >  #include <linux/spinlock.h>
> > >  #include <linux/time.h>
> > > @@ -78,6 +79,7 @@ struct sun4i_pwm_data {
> > >  struct sun4i_pwm_chip {
> > >     struct pwm_chip chip;
> > >     struct clk *clk;
> > > +   struct reset_control *rst;
> > >     void __iomem *base;
> > >     spinlock_t ctrl_lock;
> > >     const struct sun4i_pwm_data *data;
> > > @@ -365,6 +367,20 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
> > >     if (IS_ERR(pwm->clk))
> > >             return PTR_ERR(pwm->clk);
> > >
> > > +   pwm->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
> > > +   if (IS_ERR(pwm->rst)) {
> > > +           if (PTR_ERR(pwm->rst) == -EPROBE_DEFER)
> > > +                   return PTR_ERR(pwm->rst);
> > > +           dev_info(&pdev->dev, "no reset control found\n");
> >
> > I would degrade this to a dev_dbg. Otherwise this spams the log for all
> > unaffected machines.
>
> The _optional variants return NULL if the reset is not specified in the
> device tree, so this is not "no reset control found", but a real error
> that should be returned.

Correct,

Thanks for the catch,
Clément

>
> > devm_reset_control_get_optional() is defined in a section that has a
> > comment "These inline function calls will be removed once all
> > consumers have been moved over to the new explicit API.", so I guess
> > you want devm_reset_control_get_optional_exclusive or even
> > devm_reset_control_get_optional_shared here.
>
> Correct. If this driver deasserts in probe() and asserts the reset in
> remove(), this can use the refcounting _shared variant.
>
> > @Philipp: maybe a check in checkpatch that warns about introduction of
> > such new instances would be good?!
>
> Yes, that would be helpful.
>
> regards
> Philipp

Patch
diff mbox series

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 6f5840a1a82d..d194b8ebdb00 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -16,6 +16,7 @@ 
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/time.h>
@@ -78,6 +79,7 @@  struct sun4i_pwm_data {
 struct sun4i_pwm_chip {
 	struct pwm_chip chip;
 	struct clk *clk;
+	struct reset_control *rst;
 	void __iomem *base;
 	spinlock_t ctrl_lock;
 	const struct sun4i_pwm_data *data;
@@ -365,6 +367,20 @@  static int sun4i_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pwm->clk))
 		return PTR_ERR(pwm->clk);
 
+	pwm->rst = devm_reset_control_get_optional(&pdev->dev, NULL);
+	if (IS_ERR(pwm->rst)) {
+		if (PTR_ERR(pwm->rst) == -EPROBE_DEFER)
+			return PTR_ERR(pwm->rst);
+		dev_info(&pdev->dev, "no reset control found\n");
+	}
+
+	/* Deassert reset */
+	ret = reset_control_deassert(pwm->rst);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot deassert reset control\n");
+		return ret;
+	}
+
 	pwm->chip.dev = &pdev->dev;
 	pwm->chip.ops = &sun4i_pwm_ops;
 	pwm->chip.base = -1;
@@ -377,19 +393,31 @@  static int sun4i_pwm_probe(struct platform_device *pdev)
 	ret = pwmchip_add(&pwm->chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
-		return ret;
+		goto err_pwm_add;
 	}
 
 	platform_set_drvdata(pdev, pwm);
 
 	return 0;
+
+err_pwm_add:
+	reset_control_assert(pwm->rst);
+
+	return ret;
 }
 
 static int sun4i_pwm_remove(struct platform_device *pdev)
 {
 	struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = pwmchip_remove(&pwm->chip);
+	if (ret)
+		return ret;
+
+	reset_control_assert(pwm->rst);
 
-	return pwmchip_remove(&pwm->chip);
+	return 0;
 }
 
 static struct platform_driver sun4i_pwm_driver = {