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Diffstat (limited to 'Documentation/arm/SH-Mobile/zboot-rom-mmcif.txt')
| -rw-r--r-- | Documentation/arm/SH-Mobile/zboot-rom-mmcif.txt | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/arm/SH-Mobile/zboot-rom-mmcif.txt b/Documentation/arm/SH-Mobile/zboot-rom-mmcif.txt new file mode 100644 index 00000000..efff8ae2 --- /dev/null +++ b/Documentation/arm/SH-Mobile/zboot-rom-mmcif.txt @@ -0,0 +1,29 @@ +ROM-able zImage boot from MMC +----------------------------- + +An ROM-able zImage compiled with ZBOOT_ROM_MMCIF may be written to MMC and +SuperH Mobile ARM will to boot directly from the MMCIF hardware block. + +This is achieved by the mask ROM loading the first portion of the image into +MERAM and then jumping to it. This portion contains loader code which +copies the entire image to SDRAM and jumps to it. From there the zImage +boot code proceeds as normal, uncompressing the image into its final +location and then jumping to it. + +This code has been tested on an AP4EB board using the developer 1A eMMC +boot mode which is configured using the following jumper settings. +The board used for testing required a patched mask ROM in order for +this mode to function. + + 8 7 6 5 4 3 2 1 + x|x|x|x|x| |x| +S4 -+-+-+-+-+-+-+- + | | | | |x| |x on + +The zImage must be written to the MMC card at sector 1 (512 bytes) in +vrl4 format. A utility vrl4 is supplied to accomplish this. + +e.g. + vrl4 < zImage | dd of=/dev/sdX bs=512 seek=1 + +A dual-voltage MMC 4.0 card was used for testing. |