On Tue, Mar 31, 2020 at 12:13 PM Anup Patel <anup.patel@...> wrote:
>
> This patch adds SBI v0.2 compliant system reboot extension. It defines
> two functions:
> 1. sbi_reboot - A system reboot call with reboot type as parameter
> 2. sbi_shutdown - A system shutdown/poweroff call
>
> The sbi_shutdown function defined here replaces SBI v0.1 shutdown
> function.
>
> Signed-off-by: Atish Patra <atish.patra@...>
> Signed-off-by: Anup Patel <anup.patel@...>
> ---
>  riscv-sbi.adoc | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
>
> diff --git a/riscv-sbi.adoc b/riscv-sbi.adoc
> index 8137686..a39e362 100644
> --- a/riscv-sbi.adoc
> +++ b/riscv-sbi.adoc
> @@ -615,6 +615,70 @@ state of the hart at the time of return value verification.
>  | sbi_hart_get_status          |           2 |     0x48534D
>  |===
>
> +== System Reboot Extension, Extension ID: 0x53524254 (SRBT)
> +
> +The System Reboot Extension provides a set of functions that allow the
> +supervisor software to request system-level reboot or shutdown.
> +
> +[source, C]
> +----
> +struct sbiret sbi_system_reboot(unsigned long reboot_type)
> +----
> +
> +Reboot the system based on provided reboot type. This is a synchronous call
> +and is not expected to return if succeeds.
> +
> +The reboot_type parameter is 32 bit wide and has following possible values:
> +
> +[cols="<,>",options="header,compact"]
> +|===
> +| Value                        | Description
> +| 0x00000000                   | Cold reboot
> +| 0x00000001                   | Warm reboot
> +| 0x00000002 - 0xEFFFFFFF      | Reserved for future use
> +| 0xF0000000 - 0xFFFFFFFF      | Vendor or platform specific reboot type
> +| 0x100000000 - 2^XELN-1       | Reserved for RV64/RV128

The words are misleading, as it could indicate that the above types
only apply to RV32.

> +|===
> +
> +*Returns* one of the following possible SBI error codes through sbiret.error
> +upon failure.
> +
> +Cold reboot results in complete power cycle of the entire system while
> +warm reboot depends on SOC vendor design choices.
> +
> +[cols="<,>",options="header,compact"]
> +|===
> +| Error code                | Description
> +| SBI_ERR_INVALID_PARAM     | `reboot_type` is not valid.
> +| SBI_ERR_FAILED            | Reboot request failed for unknown reasons.
> +|===
> +
> +[source, C]
> +----
> +struct sbiret sbi_system_shutdown()
> +----
> +
> +Shutdown the system. This is a synchronous call and is not expected to
> +return if succeeds.
> +
> +*Returns* one of the following possible SBI error codes through sbiret.error
> +upon failure.
> +
> +[cols="<,>",options="header,compact"]
> +|===
> +| Error code                | Description
> +| SBI_ERR_FAILED            | The start request failed for unknown reasons.

The shutdown request

> +|===
> +
> +=== SRBT Function Listing
> +
> +[cols="<,,>",options="header,compact"]
> +|===
> +| Function Name                 | Function ID | Extension ID
> +| sbi_system_reboot                    |           0 |   0x53524254
> +| sbi_system_shutdown                  |           1 |   0x53524254
> +|===
> +
>  == Experimental SBI Extension Space, Extension IDs 0x0800000 through 0x08FFFFFF
>
>  No management.

Otherwise, looks good to me.

Regards,
Bin