[PATCH v3 1/5] riscv: Add boot hartid to Device tree
Bin Meng
bmeng.cn at gmail.com
Thu Mar 19 04:10:13 CET 2020
On Wed, Mar 18, 2020 at 5:19 AM 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
nits: U-Boot
remove "during" ?
> 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;
return err
> + }
> + 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;
return err
> + }
> + }
> +
> + /* Overwrite the boot-hartid as U-Boot is the last state BL */
typo: stage
> + fdt_setprop_u32(blob, chosen_offset, "boot-hartid",
> + gd->arch.boot_hart);
> +
> return 0;
> }
>
> --
Regards,
Bin
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