This patch follows up on a discussion of ways to improve support for the sunxi FEL ("USB boot") mechanism, especially with regard to boot scripts, see: https://groups.google.com/d/msg/linux-sunxi/wBEGUoLNRro/rHGq6nSYCQAJ
The idea is to convert the (currently unused) "pad" bytes in the SPL header into an area where data can be passed to U-Boot. To do this safely, we have to make sure that we're actually using our "sunxi" flavor of the SPL, and not the Allwinner boot0.
The modified mksunxiboot introduces a special signature to the SPL header in place of the "pub_head_size" field. This can be used to reliably distinguish between compatible versions of sunxi SPL and anything else (older variants or Allwinner's boot0).
Signed-off-by: Bernhard Nortmann bernhard.nortmann@web.de ---
Changes in v3: - adapted to use asm/arch/spl.h
Changes in v2: - Rename field to fel_script_address, discard fel_data_size - Clearing header fields is no longer needed, as mksunxiboot.c zeroes entire image first
arch/arm/include/asm/arch-sunxi/spl.h | 19 ++++++++++++++++++- tools/mksunxiboot.c | 4 ++++ 2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/arch-sunxi/spl.h b/arch/arm/include/asm/arch-sunxi/spl.h index 751de75..08fe32d 100644 --- a/arch/arm/include/asm/arch-sunxi/spl.h +++ b/arch/arm/include/asm/arch-sunxi/spl.h @@ -10,6 +10,8 @@ #define _ASM_ARCH_SPL_H_
#define BOOT0_MAGIC "eGON.BT0" +#define SPL_SIGNATURE "SPL" /* marks "sunxi" SPL header */ +#define SPL_HEADER_VERSION 1
/* boot head definition from sun4i boot code */ struct boot_file_head { @@ -22,8 +24,23 @@ struct boot_file_head { * by the boot ROM. To be compatible with Allwinner tools we * would need to implement the proper fields here instead of * padding. + * + * Actually we want the ability to recognize our "sunxi" variant + * of the SPL. To do so, let's place a special signature into the + * "pub_head_size" field. We can reasonably expect Allwinner's + * boot0 to always have the upper 16 bits of this set to 0 (after + * all the value shouldn't be larger than the limit imposed by + * SRAM size). + * If the signature is present (at 0x14), then we know it's safe + * to use the remaining 8 bytes (at 0x18) for our own purposes. + * (E.g. sunxi-tools "fel" utility can pass information there.) */ - uint8_t pad[12]; /* align to 32 bytes */ + union { + uint32_t pub_head_size; + uint8_t spl_signature[4]; + }; + uint32_t fel_script_address; + uint32_t reserved; /* padding, align to 32 bytes */ };
#endif diff --git a/tools/mksunxiboot.c b/tools/mksunxiboot.c index 54f4d05..9c1c5b7 100644 --- a/tools/mksunxiboot.c +++ b/tools/mksunxiboot.c @@ -118,6 +118,10 @@ int main(int argc, char *argv[]) ALIGN(file_size + sizeof(struct boot_file_head), BLOCK_SIZE); img.header.b_instruction = cpu_to_le32(img.header.b_instruction); img.header.length = cpu_to_le32(img.header.length); + + memcpy(img.header.spl_signature, SPL_SIGNATURE, 3); /* "sunxi" marker */ + img.header.spl_signature[3] = SPL_HEADER_VERSION; + gen_check_sum(&img.header);
count = write(fd_out, &img, le32_to_cpu(img.header.length));