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sunxi: (mksunxiboot) signature to indicate "sunxi" SPL variant 

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>
Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
utp
Bernhard Nortmann 2015-09-17 18:52:51 +02:00 committed by Hans de Goede
parent e954eb8028
commit a188438175
2 changed files with 22 additions and 1 deletions
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19
arch/arm/include/asm/arch-sunxi/spl.h
View File

@ -9,6 +9,8 @@
#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 {
@ -21,8 +23,23 @@ 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

4
tools/mksunxiboot.c
View File

@ -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));