[RFC PATCH] lib: utils: fdt_domain: Use consistent device-tree address when next-arg1 is missing

[Anup Patel]

On Fri, Jun 28, 2024 at 1:54 PM Yu Chien Peter Lin
<peterlin at andestech.com> wrote:
>
> The diagram shows the boot-flow involving OP-TEE OS initialization:
>
>     (1)-----------+
>      | U-Boot SPL |
>      +------------+
>          |
>          v
>     (2)-------------------------------------------------------------+
>      | OpenSBI (fw_dynamic)                                         |
>      |                (4)------------------------+                  |
>      |                 | optee dispatcher driver |                  |
>      +-----------------+-------^---------|-------+------------------+
> M-mode   |  (coldboot domain)  |         |
> ---------+--(trusted domain)---+----+----+-(untrusted domain)--------
> S-mode   |                     |    |    |
>          v                     |    |    v
>     (3)---------------------------+ |(5)----------------------------+
>      | OP-TEE OS                  | | | U-Boot                      |
>      +----------------------------+ | +-----------------------------+
>                                     |    |
>                                     |    v
>                                     |(6)----------------------------+
>                                     | | Linux                       |
>                                     | +-----------------------------+
>
> As OP-TEE OS has device-tree node fixups that need to be passed
> through the next boot stages, such as reserved memory node shown
> below:
>
>   reserved-memory {
>     #address-cells = <0x00000002>;
>     #size-cells = <0x00000002>;
>     ranges;
>     optee_core at f1000000 {
>       no-map;
>       reg = <0x00000000 0xf1000000   // OP-TEE OS base address
>              0x00000000 0x01000000>;
>     };
>     <...>
>   };
>
> Instead of using 0x0 as default value, allow identical next-arg1
> to be used by non-coldboot domain (i.e., untrusted domain), when
> the next-arg1 is not provided.
>
> Also, update the document about next-arg1 of domain instance.
>
> Signed-off-by: Yu Chien Peter Lin <peterlin at andestech.com>
> Reviewed-by: Alvin Chang <alvinga at andestech.com>

This approach looks good to me.

Reviewed-by: Anup Patel <anup at brainfault.org>

I will wait 2 more days to see if anyone has objections.

Regards,
Anup

> ---
>  docs/domain_support.md     | 4 +---
>  lib/utils/fdt/fdt_domain.c | 3 +--
>  2 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/docs/domain_support.md b/docs/domain_support.md
> index b34e43a..1a40068 100644
> --- a/docs/domain_support.md
> +++ b/docs/domain_support.md
> @@ -180,9 +180,7 @@ The DT properties of a domain instance DT node are as follows:
>    boot HART of the domain instance.
>  * **next-arg1** (Optional) - The 64 bit next booting stage arg1 for the
>    domain instance. If this DT property is not available and coldboot HART
> -  is not assigned to the domain instance then **0x0** is used as default
> -  value. If this DT property is not available and coldboot HART is assigned
> -  to the domain instance then **next booting stage arg1 of coldboot HART**
> +  is not assigned to the domain instance then **next booting stage arg1 of coldboot HART**
>    is used as default value.
>  * **next-addr** (Optional) - The 64 bit next booting stage address for the
>    domain instance. If this DT property is not available and coldboot HART
> diff --git a/lib/utils/fdt/fdt_domain.c b/lib/utils/fdt/fdt_domain.c
> index fa1c357..a13daa6 100644
> --- a/lib/utils/fdt/fdt_domain.c
> +++ b/lib/utils/fdt/fdt_domain.c
> @@ -395,8 +395,7 @@ static int __fdt_parse_domain(void *fdt, int domain_offset, void *opaque)
>                 val64 = fdt32_to_cpu(val[0]);
>                 val64 = (val64 << 32) | fdt32_to_cpu(val[1]);
>         } else {
> -               if (domain_offset == *cold_domain_offset)
> -                       val64 = sbi_scratch_thishart_ptr()->next_arg1;
> +               val64 = sbi_scratch_thishart_ptr()->next_arg1;
>         }
>         dom->next_arg1 = val64;
>
> --
> 2.34.1
>