On 2/4/26 9:01 PM, Marco Felsch wrote:
> Add support to store a FDT within the scratch area. The user needs to
> query the location and size via imx_scratch_get_fdt() which can be used
> afterwards to write the actual FDT into it.
>
> Signed-off-by: Marco Felsch <[email protected]>
> ---
> arch/arm/mach-imx/scratch.c | 24 ++++++++++++++++++++++++
> common/Kconfig | 14 ++++++++++++++
> include/mach/imx/scratch.h | 2 ++
> 3 files changed, 40 insertions(+)
>
> diff --git a/arch/arm/mach-imx/scratch.c b/arch/arm/mach-imx/scratch.c
> index
> e4e2d25969f061c9fcdfd7c3d87701b715eb2805..da138445dfb352f2f3497be77004aefc7d46f188
> 100644
> --- a/arch/arm/mach-imx/scratch.c
> +++ b/arch/arm/mach-imx/scratch.c
> @@ -16,7 +16,10 @@ struct imx_scratch_space {
> u32 bootrom_log[128];
> u32 reserved[128]; /* reserve for bootrom log */
> struct optee_header optee_hdr;
> + /* FDT needs an 8 byte alignment */
> + u8 fdt[CONFIG_SCRATCH_FDT_SIZE] __aligned(8);
> };
> +static_assert(sizeof(struct imx_scratch_space) <= CONFIG_SCRATCH_SIZE);
>
> static struct imx_scratch_space *scratch;
>
> @@ -92,3 +95,24 @@ const struct optee_header *imx_scratch_get_optee_hdr(void)
>
> return &scratch->optee_hdr;
> }
> +
> +u8 *imx_scratch_get_fdt(unsigned int *fdt_sz)
> +{
> + unsigned int sz;
> +
> + if (!scratch) {
> + if (IN_PBL)
> + return ERR_PTR(-EINVAL);
> + else
> + scratch = (void *)arm_mem_scratch_get();
> + }
> +
> + sz = sizeof(scratch->fdt);
> + if (sz == 0)
> + return NULL;
> +
> + if (fdt_sz)
> + *fdt_sz = sz;
> +
> + return scratch->fdt;
> +}
> diff --git a/common/Kconfig b/common/Kconfig
> index
> 50c26695b2b56a943edfd00a7e0cb1067ad269a9..265652900a5632177d36efa84d590be6db2e7015
> 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -304,6 +304,20 @@ config SCRATCH_SIZE
> default 0x8000
> prompt "Scratch size"
>
> +config SCRATCH_FDT_SIZE
> + hex
> + default 0x0
> + prompt "Scratch FDT size"
> + help
> + The size of the scratch area used as destination to load and optional
> + decompress the barebox builtin DTB into it. Can be 0x0 if early FDT
> + support is not requied.
> +
> + If specified, SCRATCH_FDT_SIZE <= SCRATCH_SIZE must be ensured.
> +
> + This option should match the OP-TEE's CFG_DTB_MAX_SIZE configuration
> + if used by OP-TEE.
AFAIU, this is a workaround because OP-TEE doesn't accept outside
information about how big the DTB buffer is, just its base address.
In that case, this should go to security/Kconfig and be named something
like PBL_OPTEE_DTB_MAX_SIZE. There's no need to ask every user that
configures barebox about this.
Cheers,
Ahmad
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