diff mbox series

[3/3] serial: sh-sci: Add reset support for RZ/G2L SoC

Message ID 20211103173127.13701-4-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State Superseded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. 3, 2021, 5:31 p.m. UTC 
On RZ/G2L devices should be explicitly pulled out of reset for it
to work. This patch adds support to read the "resets" property and
performs 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>
---
Hi Geert,
For handling the resets I was in dual mind whether to perform
reset based on compatible strings or soc-id, let me know your
thoughts. Currently no SoC's use "renesas,sci" so using the same
for performing the reset operation for SCI.
---
 drivers/tty/serial/sh-sci.c | 50 +++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 7 deletions(-)

Comments

Geert Uytterhoeven Nov. 8, 2021, 4:39 p.m. UTC | #1 
Hi Prabhakar,

On Wed, Nov 3, 2021 at 6:31 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> On RZ/G2L devices should be explicitly pulled out of reset for it
> to work. This patch adds support to read the "resets" property and
> performs 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>

Thanks for your patch!

> ---
> Hi Geert,
> For handling the resets I was in dual mind whether to perform
> reset based on compatible strings or soc-id, let me know your
> thoughts. Currently no SoC's use "renesas,sci" so using the same
> for performing the reset operation for SCI.

We do, on H8/300.

> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -3203,23 +3204,58 @@ 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 plat_sci_port *p;
>         struct sci_port *sp;
>         const void *data;
>         int id;
>
>         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);
> +       if (!strcmp(of_id->compatible, "renesas,scif-r9a07g044") ||
> +           !strcmp(of_id->compatible, "renesas,sci")) {

This will match on H8/300, too, which doesn't have resets.
Please match against "renesas,sci-r9a07g044" instead.

Please don't use explicit strcmp() calls here, but add a flag to
of_sci_match[].data.

> +               struct reset_control *rstc;
> +               int ret;
> +
> +               rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
> +               if (IS_ERR(rstc)) {
> +                       dev_err(&pdev->dev, "Error: missing reset ctrl\n");
> +                       return ERR_PTR(PTR_ERR(rstc));
> +               }
> +
> +               ret = reset_control_deassert(rstc);
> +               if (ret) {
> +                       dev_err(&pdev->dev, "failed to deassert %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;
>

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, 12:33 a.m. UTC | #2 
Hi Geert,

Thank you for the review.

On Mon, Nov 8, 2021 at 4:40 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Wed, Nov 3, 2021 at 6:31 PM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> > On RZ/G2L devices should be explicitly pulled out of reset for it
> > to work. This patch adds support to read the "resets" property and
> > performs 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>
>
> Thanks for your patch!
>
> > ---
> > Hi Geert,
> > For handling the resets I was in dual mind whether to perform
> > reset based on compatible strings or soc-id, let me know your
> > thoughts. Currently no SoC's use "renesas,sci" so using the same
> > for performing the reset operation for SCI.
>
> We do, on H8/300.
>
Missed that.

> > --- a/drivers/tty/serial/sh-sci.c
> > +++ b/drivers/tty/serial/sh-sci.c
> > @@ -3203,23 +3204,58 @@ 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 plat_sci_port *p;
> >         struct sci_port *sp;
> >         const void *data;
> >         int id;
> >
> >         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);
> > +       if (!strcmp(of_id->compatible, "renesas,scif-r9a07g044") ||
> > +           !strcmp(of_id->compatible, "renesas,sci")) {
>
> This will match on H8/300, too, which doesn't have resets.
> Please match against "renesas,sci-r9a07g044" instead.
>
> Please don't use explicit strcmp() calls here, but add a flag to
> of_sci_match[].data.
>
Agreed, does the below hunk look good for handling the reset?

-#define SCI_OF_DATA(type, regtype)     (void *)((type) << 16 | (regtype))
+#define SCIx_RESET                             BIT(31)
+#define SCI_OF_DATA(type, regtype, reset)      (void *)(reset |
(type) << 16 | (regtype))
 #define SCI_OF_TYPE(data)              ((unsigned long)(data) >> 16)
 #define SCI_OF_REGTYPE(data)           ((unsigned long)(data) & 0xffff)

@@ -3169,7 +3170,11 @@ static const struct of_device_id of_sci_match[] = {
        },
        {
                .compatible = "renesas,scif-r9a07g044",
-               .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE),
+               .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE,
SCIx_RESET),
+       },
+       {
+               .compatible = "renesas,sci-r9a07g044",
+               .data = SCI_OF_DATA(PORT_SCI, SCIx_SCI_REGTYPE, SCIx_RESET),
        },

Cheers,
Prabhakar

> > +               struct reset_control *rstc;
> > +               int ret;
> > +
> > +               rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
> > +               if (IS_ERR(rstc)) {
> > +                       dev_err(&pdev->dev, "Error: missing reset ctrl\n");
> > +                       return ERR_PTR(PTR_ERR(rstc));
> > +               }
> > +
> > +               ret = reset_control_deassert(rstc);
> > +               if (ret) {
> > +                       dev_err(&pdev->dev, "failed to deassert %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;
> >
>
> 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
Geert Uytterhoeven Nov. 9, 2021, 7:49 a.m. UTC | #3 
Hi Prabhakar,

On Tue, Nov 9, 2021 at 1:34 AM Lad, Prabhakar
<prabhakar.csengg@gmail.com> wrote:
> On Mon, Nov 8, 2021 at 4:40 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Wed, Nov 3, 2021 at 6:31 PM Lad Prabhakar
> > <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> > > On RZ/G2L devices should be explicitly pulled out of reset for it
> > > to work. This patch adds support to read the "resets" property and
> > > performs 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>
> >
> > Thanks for your patch!
> >
> > > ---
> > > Hi Geert,
> > > For handling the resets I was in dual mind whether to perform
> > > reset based on compatible strings or soc-id, let me know your
> > > thoughts. Currently no SoC's use "renesas,sci" so using the same
> > > for performing the reset operation for SCI.
> >
> > We do, on H8/300.
> >
> Missed that.
>
> > > --- a/drivers/tty/serial/sh-sci.c
> > > +++ b/drivers/tty/serial/sh-sci.c
> > > @@ -3203,23 +3204,58 @@ 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 plat_sci_port *p;
> > >         struct sci_port *sp;
> > >         const void *data;
> > >         int id;
> > >
> > >         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);
> > > +       if (!strcmp(of_id->compatible, "renesas,scif-r9a07g044") ||
> > > +           !strcmp(of_id->compatible, "renesas,sci")) {
> >
> > This will match on H8/300, too, which doesn't have resets.
> > Please match against "renesas,sci-r9a07g044" instead.
> >
> > Please don't use explicit strcmp() calls here, but add a flag to
> > of_sci_match[].data.
> >
> Agreed, does the below hunk look good for handling the reset?
>
> -#define SCI_OF_DATA(type, regtype)     (void *)((type) << 16 | (regtype))
> +#define SCIx_RESET                             BIT(31)
> +#define SCI_OF_DATA(type, regtype, reset)      (void *)(reset |
> (type) << 16 | (regtype))
>  #define SCI_OF_TYPE(data)              ((unsigned long)(data) >> 16)
>  #define SCI_OF_REGTYPE(data)           ((unsigned long)(data) & 0xffff)
>
> @@ -3169,7 +3170,11 @@ static const struct of_device_id of_sci_match[] = {
>         },
>         {
>                 .compatible = "renesas,scif-r9a07g044",
> -               .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE),
> +               .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE,
> SCIx_RESET),
> +       },
> +       {
> +               .compatible = "renesas,sci-r9a07g044",
> +               .data = SCI_OF_DATA(PORT_SCI, SCIx_SCI_REGTYPE, SCIx_RESET),
>         },

That's what I had in mind.

But upon second thought, it might be better to just drop the check,
and obtain an optional reset instead?
After all the reset requirement is not a feature of this specific
SCI(F) variant, but an SoC integration feature.  And deasserting
the reset on other SoCs that have a reset should be fine.

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, 9:02 a.m. UTC | #4 
Hi Geert,

On Tue, Nov 9, 2021 at 7:50 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Tue, Nov 9, 2021 at 1:34 AM Lad, Prabhakar
> <prabhakar.csengg@gmail.com> wrote:
> > On Mon, Nov 8, 2021 at 4:40 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Wed, Nov 3, 2021 at 6:31 PM Lad Prabhakar
> > > <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> > > > On RZ/G2L devices should be explicitly pulled out of reset for it
> > > > to work. This patch adds support to read the "resets" property and
> > > > performs 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>
> > >
> > > Thanks for your patch!
> > >
> > > > ---
> > > > Hi Geert,
> > > > For handling the resets I was in dual mind whether to perform
> > > > reset based on compatible strings or soc-id, let me know your
> > > > thoughts. Currently no SoC's use "renesas,sci" so using the same
> > > > for performing the reset operation for SCI.
> > >
> > > We do, on H8/300.
> > >
> > Missed that.
> >
> > > > --- a/drivers/tty/serial/sh-sci.c
> > > > +++ b/drivers/tty/serial/sh-sci.c
> > > > @@ -3203,23 +3204,58 @@ 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 plat_sci_port *p;
> > > >         struct sci_port *sp;
> > > >         const void *data;
> > > >         int id;
> > > >
> > > >         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);
> > > > +       if (!strcmp(of_id->compatible, "renesas,scif-r9a07g044") ||
> > > > +           !strcmp(of_id->compatible, "renesas,sci")) {
> > >
> > > This will match on H8/300, too, which doesn't have resets.
> > > Please match against "renesas,sci-r9a07g044" instead.
> > >
> > > Please don't use explicit strcmp() calls here, but add a flag to
> > > of_sci_match[].data.
> > >
> > Agreed, does the below hunk look good for handling the reset?
> >
> > -#define SCI_OF_DATA(type, regtype)     (void *)((type) << 16 | (regtype))
> > +#define SCIx_RESET                             BIT(31)
> > +#define SCI_OF_DATA(type, regtype, reset)      (void *)(reset |
> > (type) << 16 | (regtype))
> >  #define SCI_OF_TYPE(data)              ((unsigned long)(data) >> 16)
> >  #define SCI_OF_REGTYPE(data)           ((unsigned long)(data) & 0xffff)
> >
> > @@ -3169,7 +3170,11 @@ static const struct of_device_id of_sci_match[] = {
> >         },
> >         {
> >                 .compatible = "renesas,scif-r9a07g044",
> > -               .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE),
> > +               .data = SCI_OF_DATA(PORT_SCIF, SCIx_RZ_SCIFA_REGTYPE,
> > SCIx_RESET),
> > +       },
> > +       {
> > +               .compatible = "renesas,sci-r9a07g044",
> > +               .data = SCI_OF_DATA(PORT_SCI, SCIx_SCI_REGTYPE, SCIx_RESET),
> >         },
>
> That's what I had in mind.
>
> But upon second thought, it might be better to just drop the check,
> and obtain an optional reset instead?
Agreed, will do that.

> After all the reset requirement is not a feature of this specific
> SCI(F) variant, but an SoC integration feature.  And deasserting
> the reset on other SoCs that have a reset should be fine.
>
Indeed.

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..a0f68b887e29 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 +3204,58 @@  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 plat_sci_port *p;
 	struct sci_port *sp;
 	const void *data;
 	int id;
 
 	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);
+	if (!strcmp(of_id->compatible, "renesas,scif-r9a07g044") ||
+	    !strcmp(of_id->compatible, "renesas,sci")) {
+		struct reset_control *rstc;
+		int ret;
+
+		rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+		if (IS_ERR(rstc)) {
+			dev_err(&pdev->dev, "Error: missing reset ctrl\n");
+			return ERR_PTR(PTR_ERR(rstc));
+		}
+
+		ret = reset_control_deassert(rstc);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to deassert %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 +3263,11 @@  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 +3354,8 @@  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) {