Hi Caleb, On Tue, 24 Oct 2023 at 04:32, Caleb Connolly <caleb.conno...@linaro.org> wrote: > > Add a new config option to allow u-boot to reuse the FDT provided by the
U-Boot (please fix throughout) > previous stage bootloader when available. > > On some boards the previous stage bootloader can populate > platform-specific parts of the devicetree such as the memory node, this > allows us to avoid hardcoding it in u-boot and instead determine it > dynamically at runtime. > > Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org> > --- > This patch will improve generic support for Qualcomm boards by enabling > us to configure the memory map at runtime rather than having hardcoded > maps on a per-device basis. I've gone for this approach initially to try > and avoid introducing board specific code where possible, but I'm happy > to rework this into mach-snapdragon if that's preferred. Do you think it could use bloblist instead? I did send a patch to use the FDT in the bloblist: https://patchwork.ozlabs.org/project/uboot/patch/20230926141514.2101787-40-...@chromium.org/ Regards, Simon > --- > base-commit: e65b5d35c9116485366bb08138043d51220551da > > // Caleb (they/them) > --- > arch/arm/lib/save_prev_bl_data.c | 7 +++++++ > boot/Kconfig | 10 ++++++++++ > include/init.h | 9 +++++++++ > lib/fdtdec.c | 7 ++++++- > 4 files changed, 32 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/lib/save_prev_bl_data.c > b/arch/arm/lib/save_prev_bl_data.c > index f7b23faf0d66..b0608502535e 100644 > --- a/arch/arm/lib/save_prev_bl_data.c > +++ b/arch/arm/lib/save_prev_bl_data.c > @@ -45,6 +45,13 @@ bool is_addr_accessible(phys_addr_t addr) > return false; > } > > +phys_addr_t get_prev_bl_fdt_addr(void) > +{ > + if (!is_addr_accessible((phys_addr_t)reg0)) > + return 0; > + return reg0; > +} > + > int save_prev_bl_data(void) > { > struct fdt_header *fdt_blob; > diff --git a/boot/Kconfig b/boot/Kconfig > index a01e6cb8aafe..c127ba254589 100644 > --- a/boot/Kconfig > +++ b/boot/Kconfig > @@ -1599,6 +1599,16 @@ config SAVE_PREV_BL_INITRAMFS_START_ADDR > If no initramfs was provided by previous bootloader, no env > variables > will be created. > > +config USE_PREV_BL_FDT > + depends on SAVE_PREV_BL_FDT_ADDR && !OF_BOARD > + bool "Use the FDT provided by the previous stage bootloader" > + help > + When u-boot is chain-loaded from a previous bootloader, enable this > option > + to use the FDT provided by the previous bootloader instead of any > built-in > + to u-boot. > + > + If no FDT was available, u-boot will fall back to its internal FDT. > + > menu "Configuration editor" > > config CEDIT > diff --git a/include/init.h b/include/init.h > index 4e7fe26c2004..58604cd98758 100644 > --- a/include/init.h > +++ b/include/init.h > @@ -168,6 +168,15 @@ defined(CONFIG_SAVE_PREV_BL_FDT_ADDR) > * Return: 0 if ok; -ENODATA on error > */ > int save_prev_bl_data(void); > + > +/** > + * get_prev_bl_fdt_addr - When u-boot is chainloaded, get the address > + * of the FDT passed by the previous bootloader. > + * > + * Return: the address of the FDT passed by the previous bootloader > + * or 0 if not found. > + */ > +phys_addr_t get_prev_bl_fdt_addr(void); > #endif > > /** > diff --git a/lib/fdtdec.c b/lib/fdtdec.c > index 7a6916764835..85425f2dc1ee 100644 > --- a/lib/fdtdec.c > +++ b/lib/fdtdec.c > @@ -1222,7 +1222,7 @@ static int uncompress_blob(const void *src, ulong > sz_src, void **dstp) > */ > static void *fdt_find_separate(void) > { > - void *fdt_blob = NULL; > + void *fdt_blob = NULL, *prevbl_fdt_blob; > > if (IS_ENABLED(CONFIG_SANDBOX)) > return NULL; > @@ -1234,6 +1234,11 @@ static void *fdt_find_separate(void) > else > fdt_blob = (ulong *)__bss_end; > #else > +#if defined(CONFIG_USE_PREV_BL_FDT) > + prevbl_fdt_blob = (void *)get_prev_bl_fdt_addr(); > + if (prevbl_fdt_blob) > + return prevbl_fdt_blob; > +#endif > /* FDT is at end of image */ > fdt_blob = (ulong *)_end; > > Regards, SImon
