[PATCH v2 2/2] lib: utils/timer: mtimer: add MIPS P8700 compatible

[Anup Patel]

On Mon, Oct 27, 2025 at 6:42 PM Benoît Monin <benoit.monin at bootlin.com> wrote:
>
> The MTIMER of the MIPS P8700 is compliant with the ACLINT specification,
> so add a compatible string for it.
>
> In a multi-cluster configuration, there is one MTIMER per cluster, each
> associated with the HARTS of the cluster. So we do not have a MTIMER
> with no associated HARTs to use as our reference.
>
> To be able to select a reference MTIMER in that case, add a quirk to look
> up an optional device tree property that indicate which MTIMER to use.
> For the MIPS P8700, the property is "mips,reference-mtimer".
>
> Signed-off-by: Benoît Monin <benoit.monin at bootlin.com>
> ---
>  lib/utils/timer/fdt_timer_mtimer.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c
> index e1fd051..e98c99f 100644
> --- a/lib/utils/timer/fdt_timer_mtimer.c
> +++ b/lib/utils/timer/fdt_timer_mtimer.c
> @@ -20,6 +20,7 @@ struct timer_mtimer_quirks {
>         unsigned int    clint_mtime_offset;
>         bool            clint_without_mtime;
>         bool            has_64bit_mmio;
> +       const char      *dt_ref_prop;
>  };
>
>  struct timer_mtimer_node {
> @@ -39,6 +40,7 @@ static int timer_mtimer_cold_init(const void *fdt, int nodeoff,
>         struct aclint_mtimer_data *mt;
>         const struct timer_mtimer_quirks *quirks = match->data;
>         bool is_clint = quirks && quirks->is_clint;
> +       bool is_ref = false;
>
>         mtn = sbi_zalloc(sizeof(*mtn));
>         if (!mtn)
> @@ -110,13 +112,18 @@ static int timer_mtimer_cold_init(const void *fdt, int nodeoff,
>         }
>
>         /*
> -        * Select first MTIMER device with no associated HARTs as our
> -        * reference MTIMER device. This is only a temporary strategy
> -        * of selecting reference MTIMER device. In future, we might
> -        * define an optional DT property or some other mechanism to
> -        * help us select the reference MTIMER device.
> +        * If we have a DT property to indicate which MTIMER is the reference,
> +        * select the first MTIMER device that has it. Otherwise, select the
> +        * first MTIMER device with no associated HARTs as our reference.
>          */
> -       if (!mt->hart_count && !mt_reference) {
> +       if (quirks && quirks->dt_ref_prop) {
> +               if (fdt_getprop(fdt, nodeoff, quirks->dt_ref_prop, NULL))
> +                       is_ref = true;
> +       } else if (!mt->hart_count) {
> +               is_ref = true;
> +       }
> +
> +       if (is_ref && !mt_reference) {
>                 mt_reference = mt;
>                 /*
>                  * Set reference for already propbed MTIMER devices
> @@ -152,6 +159,10 @@ static const struct timer_mtimer_quirks thead_aclint_quirks = {
>         .has_64bit_mmio         = false,
>  };
>
> +static const struct timer_mtimer_quirks mips_aclint_quirks = {
> +       .dt_ref_prop            = "mips,reference-mtimer",
> +};
> +

I think this DT property can be useful to other platforms as well.
How about "riscv,reference-mtimer" as a DT property ? This way
you don't need to make it as MIPS quirk.

>  static const struct fdt_match timer_mtimer_match[] = {
>         { .compatible = "riscv,clint0", .data = &sifive_clint_quirks },
>         { .compatible = "sifive,clint0", .data = &sifive_clint_quirks },
> @@ -159,6 +170,8 @@ static const struct fdt_match timer_mtimer_match[] = {
>         { .compatible = "thead,c900-clint", .data = &thead_clint_quirks },
>         { .compatible = "thead,c900-aclint-mtimer",
>           .data = &thead_aclint_quirks },
> +       { .compatible = "mips,p8700-aclint-mtimer",
> +         .data = &mips_aclint_quirks },
>         { .compatible = "riscv,aclint-mtimer" },
>         { },
>  };
>
> --
> 2.51.1
>
>
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Regards,
Anup