On 26-02-06, Ahmad Fatoum wrote: > > > 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.
This is correct for the bl_params case. In case of transfer-lists the size could be detected by OP-TEE OS. > 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. This would bind the FDT support to OP-TEE but the FDT could be used by other boot binaries as well. In the speak of ARM, it could be used by the TF-A. In the speak of RISC-V, it could be used by opensbi. Therefore I made it generic. I wanted to avoid multiple Kconfig options to configure the scatch space for: - OP-TEE FDT - OpenSBI FDT - TF-A FDT I'm currently unsure if dropping the OP-TEE note from the help message helps. But I have no hard feelings about PBL_OPTEE_DTB_MAX_SIZE either. Regards, Marco > > > Cheers, > Ahmad > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > > -- #gernperDu #CallMeByMyFirstName Pengutronix e.K. | | Steuerwalder Str. 21 | https://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
