diff mbox series

[v2,3/3] serial: sh-sci: Add support to deassert/assert reset line

Message ID 20211109121631.26687-4-prabhakar.mahadev-lad.rj@bp.renesas.com (mailing list archive)
State Superseded
Delegated to: Geert Uytterhoeven
Headers show
Series RZ/G2L SCI support and sh-sci driver update | expand

Commit Message

Prabhakar Nov. 9, 2021, 12:16 p.m. UTC 
On RZ/G2L SoC we need to explicitly deassert the reset line
for the device to work, use this opportunity to deassert/assert
reset line in sh-sci driver.

This patch adds support to read the "resets" property (if available)
from DT and perform deassert/assert when required.

Also, propagate the error to the caller of sci_parse_dt() instead of
returning NULL in case of failure.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v1->v2
* deassert/assert reset line if available on all SoC's
* Updated commit message
---
 drivers/tty/serial/sh-sci.c | 47 ++++++++++++++++++++++++++++++-------
 1 file changed, 39 insertions(+), 8 deletions(-)

Comments

Philipp Zabel Nov. 9, 2021, 12:21 p.m. UTC | #1 
On Tue, 2021-11-09 at 12:16 +0000, Lad Prabhakar wrote:
> On RZ/G2L SoC we need to explicitly deassert the reset line
> for the device to work, use this opportunity to deassert/assert
> reset line in sh-sci driver.
> 
> This patch adds support to read the "resets" property (if available)
> from DT and perform deassert/assert when required.
> 
> Also, propagate the error to the caller of sci_parse_dt() instead of
> returning NULL in case of failure.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp
Geert Uytterhoeven Nov. 9, 2021, 12:57 p.m. UTC | #2 
Hi Prabhakar,

On Tue, Nov 9, 2021 at 1:17 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> On RZ/G2L SoC we need to explicitly deassert the reset line
> for the device to work, use this opportunity to deassert/assert
> reset line in sh-sci driver.
>
> This patch adds support to read the "resets" property (if available)
> from DT and perform deassert/assert when required.
>
> Also, propagate the error to the caller of sci_parse_dt() instead of
> returning NULL in case of failure.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
> v1->v2
> * deassert/assert reset line if available on all SoC's
> * Updated commit message

Thanks for the update!

> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -37,6 +37,7 @@
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
>  #include <linux/scatterlist.h>
>  #include <linux/serial.h>
>  #include <linux/serial_sci.h>
> @@ -3203,23 +3204,53 @@ static const struct of_device_id of_sci_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, of_sci_match);
>
> +static void sci_reset_control_assert(void *data)
> +{
> +       reset_control_assert(data);
> +}
> +
>  static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
>                                           unsigned int *dev_id)
>  {
>         struct device_node *np = pdev->dev.of_node;
> +       const struct of_device_id *of_id;

Not needed.

> +       struct reset_control *rstc;
>         struct plat_sci_port *p;
>         struct sci_port *sp;
>         const void *data;
> -       int id;
> +       int id, ret;
>
>         if (!IS_ENABLED(CONFIG_OF) || !np)
> -               return NULL;
> +               return ERR_PTR(-EINVAL);
> +
> +       of_id = of_match_device(of_sci_match, &pdev->dev);
> +       if (!of_id)
> +               return ERR_PTR(-EINVAL);
>
> -       data = of_device_get_match_data(&pdev->dev);

Please keep the old construct using of_device_get_match_data().

> +       rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
> +       if (IS_ERR(rstc)) {
> +               dev_err(&pdev->dev, "failed to get reset ctrl %ld\n", PTR_ERR(rstc));
> +               return ERR_PTR(PTR_ERR(rstc));

The error might be -EPROBE_DEFER, so please use
"return ERR_PTR(dev_err_probe(...))", to avoid printing the message
in case of probe deferral.

BTW, ERR_CAST() is a shorthand for ERR_PTR(PTR_ERR()).

> +       }
> +
> +       ret = reset_control_deassert(rstc);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to deassert reset %d\n", ret);
> +               return ERR_PTR(ret);
> +       }
> +
> +       ret = devm_add_action_or_reset(&pdev->dev, sci_reset_control_assert, rstc);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to register assert devm action, %d\n",
> +                       ret);
> +               return ERR_PTR(ret);
> +       }
> +
> +       data = of_id->data;
>
>         p = devm_kzalloc(&pdev->dev, sizeof(struct plat_sci_port), GFP_KERNEL);
>         if (!p)
> -               return NULL;
> +               return ERR_PTR(-ENOMEM);
>
>         /* Get the line number from the aliases node. */
>         id = of_alias_get_id(np, "serial");

I gave this a try on Salvator-XS, and noticed no regressions.
I will test this on more SCIF variants later.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Lad, Prabhakar Nov. 9, 2021, 1:07 p.m. UTC | #3 
Hi Geert,

Thank you for the review.

On Tue, Nov 9, 2021 at 12:58 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Tue, Nov 9, 2021 at 1:17 PM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> > On RZ/G2L SoC we need to explicitly deassert the reset line
> > for the device to work, use this opportunity to deassert/assert
> > reset line in sh-sci driver.
> >
> > This patch adds support to read the "resets" property (if available)
> > from DT and perform deassert/assert when required.
> >
> > Also, propagate the error to the caller of sci_parse_dt() instead of
> > returning NULL in case of failure.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> > ---
> > v1->v2
> > * deassert/assert reset line if available on all SoC's
> > * Updated commit message
>
> Thanks for the update!
>
> > --- a/drivers/tty/serial/sh-sci.c
> > +++ b/drivers/tty/serial/sh-sci.c
> > @@ -37,6 +37,7 @@
> >  #include <linux/of_device.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/pm_runtime.h>
> > +#include <linux/reset.h>
> >  #include <linux/scatterlist.h>
> >  #include <linux/serial.h>
> >  #include <linux/serial_sci.h>
> > @@ -3203,23 +3204,53 @@ static const struct of_device_id of_sci_match[] = {
> >  };
> >  MODULE_DEVICE_TABLE(of, of_sci_match);
> >
> > +static void sci_reset_control_assert(void *data)
> > +{
> > +       reset_control_assert(data);
> > +}
> > +
> >  static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
> >                                           unsigned int *dev_id)
> >  {
> >         struct device_node *np = pdev->dev.of_node;
> > +       const struct of_device_id *of_id;
>
> Not needed.
>
Agreed.

> > +       struct reset_control *rstc;
> >         struct plat_sci_port *p;
> >         struct sci_port *sp;
> >         const void *data;
> > -       int id;
> > +       int id, ret;
> >
> >         if (!IS_ENABLED(CONFIG_OF) || !np)
> > -               return NULL;
> > +               return ERR_PTR(-EINVAL);
> > +
> > +       of_id = of_match_device(of_sci_match, &pdev->dev);
> > +       if (!of_id)
> > +               return ERR_PTR(-EINVAL);
> >
> > -       data = of_device_get_match_data(&pdev->dev);
>
> Please keep the old construct using of_device_get_match_data().
>
OK.

> > +       rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
> > +       if (IS_ERR(rstc)) {
> > +               dev_err(&pdev->dev, "failed to get reset ctrl %ld\n", PTR_ERR(rstc));
> > +               return ERR_PTR(PTR_ERR(rstc));
>
> The error might be -EPROBE_DEFER, so please use
> "return ERR_PTR(dev_err_probe(...))", to avoid printing the message
> in case of probe deferral.
>
Agreed, will use dev_err_probe().

> BTW, ERR_CAST() is a shorthand for ERR_PTR(PTR_ERR()).
>
Thanks for the pointer.

> > +       }
> > +
> > +       ret = reset_control_deassert(rstc);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "failed to deassert reset %d\n", ret);
> > +               return ERR_PTR(ret);
> > +       }
> > +
> > +       ret = devm_add_action_or_reset(&pdev->dev, sci_reset_control_assert, rstc);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "failed to register assert devm action, %d\n",
> > +                       ret);
> > +               return ERR_PTR(ret);
> > +       }
> > +
> > +       data = of_id->data;
> >
> >         p = devm_kzalloc(&pdev->dev, sizeof(struct plat_sci_port), GFP_KERNEL);
> >         if (!p)
> > -               return NULL;
> > +               return ERR_PTR(-ENOMEM);
> >
> >         /* Get the line number from the aliases node. */
> >         id = of_alias_get_id(np, "serial");
>
> I gave this a try on Salvator-XS, and noticed no regressions.
> I will test this on more SCIF variants later.
>
Thanks, I will re-spin a v3 just for this lone patch. I hope that's OK.

Cheers,
Prabhakar

> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
diff mbox series

Patch

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 89ee43061d3a..7aced84d2f04 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -37,6 +37,7 @@ 
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/scatterlist.h>
 #include <linux/serial.h>
 #include <linux/serial_sci.h>
@@ -3203,23 +3204,53 @@  static const struct of_device_id of_sci_match[] = {
 };
 MODULE_DEVICE_TABLE(of, of_sci_match);
 
+static void sci_reset_control_assert(void *data)
+{
+	reset_control_assert(data);
+}
+
 static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
 					  unsigned int *dev_id)
 {
 	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *of_id;
+	struct reset_control *rstc;
 	struct plat_sci_port *p;
 	struct sci_port *sp;
 	const void *data;
-	int id;
+	int id, ret;
 
 	if (!IS_ENABLED(CONFIG_OF) || !np)
-		return NULL;
+		return ERR_PTR(-EINVAL);
+
+	of_id = of_match_device(of_sci_match, &pdev->dev);
+	if (!of_id)
+		return ERR_PTR(-EINVAL);
 
-	data = of_device_get_match_data(&pdev->dev);
+	rstc = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(rstc)) {
+		dev_err(&pdev->dev, "failed to get reset ctrl %ld\n", PTR_ERR(rstc));
+		return ERR_PTR(PTR_ERR(rstc));
+	}
+
+	ret = reset_control_deassert(rstc);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to deassert reset %d\n", ret);
+		return ERR_PTR(ret);
+	}
+
+	ret = devm_add_action_or_reset(&pdev->dev, sci_reset_control_assert, rstc);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register assert devm action, %d\n",
+			ret);
+		return ERR_PTR(ret);
+	}
+
+	data = of_id->data;
 
 	p = devm_kzalloc(&pdev->dev, sizeof(struct plat_sci_port), GFP_KERNEL);
 	if (!p)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	/* Get the line number from the aliases node. */
 	id = of_alias_get_id(np, "serial");
@@ -3227,11 +3258,11 @@  static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
 		id = ffz(sci_ports_in_use);
 	if (id < 0) {
 		dev_err(&pdev->dev, "failed to get alias id (%d)\n", id);
-		return NULL;
+		return ERR_PTR(-EINVAL);
 	}
 	if (id >= ARRAY_SIZE(sci_ports)) {
 		dev_err(&pdev->dev, "serial%d out of range\n", id);
-		return NULL;
+		return ERR_PTR(-EINVAL);
 	}
 
 	sp = &sci_ports[id];
@@ -3318,8 +3349,8 @@  static int sci_probe(struct platform_device *dev)
 
 	if (dev->dev.of_node) {
 		p = sci_parse_dt(dev, &dev_id);
-		if (p == NULL)
-			return -EINVAL;
+		if (IS_ERR(p))
+			return PTR_ERR(p);
 	} else {
 		p = dev->dev.platform_data;
 		if (p == NULL) {