[PATCH v2 1/4] riscv: Add boot hartid to Device tree

[Atish Patra]

On Fri, Mar 13, 2020 at 5:12 PM Atish Patra <atish.patra at wdc.com> wrote:
>
> Linux booting protocol mandates that register "a0" contains the hartid.
> However, U-boot can not pass the hartid via a0 during via standard UEFI
> protocol. DT nodes are commonly used to pass such information to the OS.
>
> Add a DT node under chosen node to indicate the boot hartid. EFI stub
> in Linux kernel will parse this node and pass it to the real kernel
> in "a0" before jumping to it.
>
> Signed-off-by: Atish Patra <atish.patra at wdc.com>
> Reviewed-by: Rick Chen <rick at andestech.com>
> ---
>  arch/riscv/lib/bootm.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
>
> diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c
> index fad16901c5f2..f927694ae32f 100644
> --- a/arch/riscv/lib/bootm.c
> +++ b/arch/riscv/lib/bootm.c
> @@ -28,6 +28,28 @@ __weak void board_quiesce_devices(void)
>
>  int arch_fixup_fdt(void *blob)
>  {
> +       u32 size;
> +       int chosen_offset, err;
> +
> +       size = fdt_totalsize(blob);
> +       err  = fdt_open_into(blob, blob, size + 32);
> +       if (err < 0) {
> +               printf("Device Tree can't be expanded to accommodate new node");
> +               return -1;
> +       }
> +       chosen_offset = fdt_path_offset(blob, "/chosen");
> +       if (chosen_offset < 0) {
> +               err = fdt_add_subnode(blob, 0, "chosen");
> +               if (err < 0) {
> +                       printf("chosen node can not be added\n");
> +                       return -1;
> +               }
> +       }
> +
> +       /* Overwrite the boot-hartid as U-Boot is the last state BL */
> +       fdt_setprop_u32(blob, chosen_offset, "boot-hartid",
> +                          gd->arch.boot_hart);
> +
>         return 0;
>  }
>
> --
> 2.25.1
>

Fixed palmer's email address. Sorry for the spam.
-- 
Regards,
Atish