projects / people / ms / u-boot.git / blame
| Commit | Line | Data |
|---|---|---|
| 13b4f639 SR |
1 | ------------------------------------------------------------------------ |
| 2 | A3M071 board support | |
| 3 | ------------------------------------------------------------------------ | |
| 4 | ||
| 5 | ||
| 6 | SPL NOR flash support: | |
| 7 | ---------------------- | |
| 8 | To boot fast into the OS (Linux), this board port integrates the SPL | |
| 9 | framework. This means, that a special, stripped-down version of | |
| 10 | U-Boot runs in the beginning. In the case of the A3M071 board, this | |
| 11 | SPL U-Boot version is less than 16 KiB big. This SPL U-Boot can either | |
| 12 | boot the OS (Linux) or a "real", full-blown U-Boot. This detection | |
| 13 | on whether to boot Linux or U-Boot is done by using the "boot_os" | |
| 14 | environment variable. If "boot_os" is set to "yes", Linux will be | |
| 15 | loaded and booted from the SPL U-Boot version. Otherwise, the | |
| 16 | full-blown U-Boot version will be loaded and run. | |
| 17 | ||
| 18 | Enabling Linux booting: | |
| 19 | ----------------------- | |
| 20 | From U-Boot: | |
| 21 | => setenv boot_os yes | |
| 22 | => saveenv | |
| 23 | ||
| 24 | From Linux: | |
| 25 | $ fw_setenv boot_os yes | |
| 26 | ||
| 27 | Enabling U-Boot booting: | |
| 28 | ------------------------ | |
| 29 | From U-Boot: | |
| 30 | => setenv boot_os no | |
| 31 | => saveenv | |
| 32 | ||
| 33 | From Linux: | |
| 34 | $ fw_setenv boot_os no | |
| 35 | ||
| 36 | ||
| 37 | Preparing Linux image(s) for booting from SPL U-Boot: | |
| 38 | ----------------------------------------------------- | |
| 39 | To boot the Linux kernel from the SPL, the DT blob (fdt) needs to get | |
| 40 | prepard/patched first. U-Boot usually inserts some dynamic values into | |
| 41 | the DT binary (blob), e.g. autodetected memory size, MAC addresses, | |
| 42 | clocks speeds etc. To generate this patched DT blob, you can use | |
| 43 | the following command: | |
| 44 | ||
| 45 | 1. Load fdt blob to SDRAM: | |
| 46 | => tftp 1800000 a3m071/a3m071.dtb | |
| 47 | ||
| 48 | 2. Set bootargs as desired for Linux booting (e.g. flash_mtd): | |
| 49 | => run mtdargs addip2 addtty | |
| 50 | ||
| 51 | 3. Use "fdt" commands to patch the DT blob: | |
| 52 | => fdt addr 1800000 | |
| 53 | => fdt boardsetup | |
| 54 | => fdt chosen | |
| 55 | ||
| 56 | 4. Display patched DT blob (optional): | |
| 57 | => fdt print | |
| 58 | ||
| 59 | 5. Save fdt to NOR flash: | |
| d62a89bd SR |
60 | => erase fc180000 fc07ffff |
| 61 | => cp.b 1800000 fc180000 10000 | |
| 13b4f639 SR |
62 | |
| 63 | All this can be integrated into an environment command: | |
| d62a89bd SR |
64 | => setenv upd_fdt 'tftp 1800000 a3m071/a3m071.dtb;run mtdargs addip addtty; \ |
| 65 | fdt addr 1800000;fdt boardsetup;fdt chosen;erase fc180000 fc07ffff; \ | |
| 66 | cp.b 1800000 fc180000 10000' | |
| 13b4f639 SR |
67 | => saveenv |
| 68 | ||
| 69 | After this, only "run upd_fdt" needs to get called to load, patch | |
| 70 | and save the DT blob into NOR flash. | |
| 71 | ||
| 72 | Additionally, the Linux kernel image has to be saved uncompressed in | |
| 73 | its uImage file (and not gzip compressed). This can be done with this | |
| 74 | command: | |
| 75 | ||
| 76 | $ mkimage -A ppc -O linux -T kernel -C none -a 0 -e 0 \ | |
| 77 | -n "Linux Kernel Image" -d vmlinux.bin uImage.uncompressed | |
| 78 | ||
| 79 | ------------------------------------------------------------------------ | |
| 80 | Stefan Roese, 2012-08-23 |