1Summary 2======= 3The README is for the boot procedure used for various DA850 (or compatible 4parts such as the AM1808) based boards. 5 6In the context of U-Boot, the board is booted in three stages. The initial 7bootloader which executes upon reset is the ROM Boot Loader (RBL) and sits 8in the internal ROM. The RBL initializes the internal memory and then 9depending on the exact board and pin configurations will initialize another 10controller (such as SPI or NAND) to continue the boot process by loading 11the secondary program loader (SPL). The SPL will initialize the system 12further (some clocks, SDRAM) and then load the full u-boot from a 13predefined location in persistent storage to DDR and jumps to the u-boot 14entry point. 15 16AIS is an image format defined by TI for the images that are to be loaded 17to memory by the RBL. The image is divided into a series of sections and 18the image's entry point is specified. Each section comes with meta data 19like the target address the section is to be copied to and the size of the 20section, which is used by the RBL to load the image. At the end of the 21image the RBL jumps to the image entry point. The AIS format allows for 22other things such as programming the clocks and SDRAM if the header is 23programmed for it. We do not take advantage of this and instead use SPL as 24it allows for additional flexibility (run-time detect of board revision, 25loading the next image from a different media, etc). 26 27 28Compilation 29=========== 30The exact build target you need will depend on the board you have. For 31Logic PD boards, or other boards which store the ethernet MAC address at 32the end of SPI flash, run 'make da850evm'. For boards which store the 33ethernet MAC address in the i2c EEPROM located at 0x50, run 34'make da850_am18xxevm'. Once this build completes you will have a 35u-boot.ais file that needs to be written to the correct persistent 36storage. 37 38 39Flashing the images to SPI 40========================== 41The AIS image can be written to SPI flash using the following commands. 42Assuming that the network is configured and enabled and the u-boot.ais file 43is tftp'able. 44 45U-Boot > sf probe 0 46U-Boot > sf erase 0 +320000 47U-Boot > tftp u-boot.ais 48U-Boot > sf write c0700000 0 $filesize 49 50Flashing the images to MMC 51========================== 52If the boot pins are set to boot from mmc, the RBL will try to load the 53next boot stage form the first couple of sectors of an external mmc card. 54As sector 0 is usually used for storing the partition information, the 55AIS image should be written at least after the first sector, but before the 56first partition begins. (e.g: make sure to leave at least 500KB of unallocated 57space at the start of the mmc when creating the partitions) 58 59CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR is used by SPL, and should 60point to the sector were the u-boot image is located. (eg. After SPL) 61 62There are 2 ways to copy the AIS image to the mmc card: 63 64 1 - Using the TI tool "uflash" 65 $ uflash -d /dev/mmcblk0 -b ./u-boot.ais -p OMAPL138 -vv 66 67 2 - using the "dd" command 68 $ dd if=u-boot.ais of=/dev/mmcblk0 seek=117 bs=512 conv=fsync 69 70uflash writes the AIS image at offset 117. For compatibility with uflash, 71CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR is set to take into account this 72offset, and the dd command is adjusted accordingly. 73 74Recovery 75======== 76 77In the case of a "bricked" board, you need to use the TI tools found 78here[1] to write the u-boot.ais file. An example of recovering to the SPI 79flash of an AM1808 would be: 80 81$ mono sfh_OMAP-L138.exe -targetType AM1808 -p /dev/ttyUSB0 \ 82 -flash_noubl /path/to/u-boot.ais 83 84For other target types and flash locations: 85 86$ mono sfh_OMAP-L138.exe -h 87 88Links 89===== 90[1] 91 http://processors.wiki.ti.com/index.php/Serial_Boot_and_Flash_Loading_Utility_for_OMAP-L138 92