[PATCH 2/5] spl: Introduce spl_board_prepare_for_optee() hook

[Simon Glass <sjg@chromium.org>]

Hi Alexandru,

On Thu, 4 Feb 2021 at 12:56, Alexandru Gagniuc <mr.nuke.me@gmail.com> wrote:
>
> OP-TEE requires some particular setup, which is not needed for linux
> or other payloads. Add a hook for platform-specific code to perform
> any OP-TEE related configuration and initialization.
>
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> ---
>  common/spl/spl.c |  6 ++++++
>  include/spl.h    | 14 ++++++++++++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/common/spl/spl.c b/common/spl/spl.c
> index cdd7b05f27..f3aaa67572 100644
> --- a/common/spl/spl.c
> +++ b/common/spl/spl.c
> @@ -160,6 +160,11 @@ __weak void spl_board_prepare_for_linux(void)
>         /* Nothing to do! */
>  }
>
> +__weak void spl_board_prepare_for_optee(void *fdt)
> +{
> +       /* Weak functions are stupid. Get rid of them! */
> +}
> +
>  __weak void spl_board_prepare_for_boot(void)
>  {
>         /* Nothing to do! */
> @@ -705,6 +710,7 @@ void board_init_r(gd_t *dummy1, ulong dummy2)
>  #if CONFIG_IS_ENABLED(OPTEE)
>         case IH_OS_TEE:
>                 debug("Jumping to U-Boot via OP-TEE\n");
> +               spl_board_prepare_for_optee(spl_image.fdt_addr);
>                 spl_optee_entry(NULL, NULL, spl_image.fdt_addr,
>                                 (void *)spl_image.entry_point);
>                 break;
> diff --git a/include/spl.h b/include/spl.h
> index e172500b5f..f94e74e217 100644
> --- a/include/spl.h
> +++ b/include/spl.h
> @@ -387,6 +387,20 @@ int spl_parse_image_header(struct spl_image_info *spl_image,
>                            const struct image_header *header);
>
>  void spl_board_prepare_for_linux(void);
> +
> +/**
> + * spl_board_prepare_for_optee() - Prepare board for an OPTEE payload
> + *
> + * Prepares the board for booting an OP-TEE payload. Initialization is platform
> + * specific, and may include configuring the TrustZone memory, and other
> + * initialization steps required by OP-TEE.
> + * Note that @fdt is not used directly by OP-TEE. OP-TEE passes this @fdt to
> + * its normal world target. This target is not guaranteed to be u-boot, so @fdt
> + * changes that would normally be done by u-boot should be done in this step.
> + *
> + * @fdt: Devicetree that will be passed on, or NULL
> + */
> +void spl_board_prepare_for_optee(void *fdt);
>  void spl_board_prepare_for_boot(void);
>  int spl_board_ubi_load_image(u32 boot_device);
>  int spl_board_boot_device(u32 boot_device);
> --
> 2.26.2
>

Reviewed-by: Simon Glass <sjg@chromium.org>

One way to get rid of the weak function would be to introduce some
sort of event handler / runner or hook system. We could have an enum
of available events and allow handlers to register themselves. Then we
could do something like:

struct event ev;

ev.type = EVT_SPL_OS_PREPARE;
ev.data.spl_os_prepare = IG_OS_TEE;
ret = event_post(&ev);
(return code -ENOSYS if nothing handled the event)

Could use a ilnker_list to set up the handlers at build time. Perhaps
could allow runtime registration if useful.

Regards,
Simon