Hi Prabhakar,
On Tue, Nov 9, 2021 at 1:34 AM Lad, Prabhakar
<prabhakar.csengg@xxxxxxxxx> wrote:
> On Mon, Nov 8, 2021 at 4:40 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > On Wed, Nov 3, 2021 at 6:31 PM Lad Prabhakar
> > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
> > > Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxx
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
