1 Summary 2 ======= 3 The README is for the boot procedure used for various DA850 (or compatible 4 parts such as the AM1808) based boards. 5 6 In the context of U-Boot, the board is booted in three stages. The initial 7 bootloader which executes upon reset is the ROM Boot Loader (RBL) and sits 8 in the internal ROM. The RBL initializes the internal memory and then 9 depending on the exact board and pin configurations will initialize another 10 controller (such as SPI or NAND) to continue the boot process by loading 11 the secondary program loader (SPL). The SPL will initialize the system 12 further (some clocks, SDRAM) and then load the full u-boot from a 13 predefined location in persistent storage to DDR and jumps to the u-boot 14 entry point. 15 16 AIS is an image format defined by TI for the images that are to be loaded 17 to memory by the RBL. The image is divided into a series of sections and 18 the image's entry point is specified. Each section comes with meta data 19 like the target address the section is to be copied to and the size of the 20 section, which is used by the RBL to load the image. At the end of the 21 image the RBL jumps to the image entry point. The AIS format allows for 22 other things such as programming the clocks and SDRAM if the header is 23 programmed for it. We do not take advantage of this and instead use SPL as 24 it allows for additional flexibility (run-time detect of board revision, 25 loading the next image from a different media, etc). 26 27 28 Compilation 29 =========== 30 The exact build target you need will depend on the board you have. For 31 Logic PD boards, or other boards which store the ethernet MAC address at 32 the end of SPI flash, run 'make da850evm'. For boards which store the 33 ethernet MAC address in the i2c EEPROM located at 0x50, run 34 'make da850_am18xxevm'. Once this build completes you will have a 35 u-boot.ais file that needs to be written to the correct persistent 36 storage. 37 38 39 Flashing the images to SPI 40 ========================== 41 The AIS image can be written to SPI flash using the following commands. 42 Assuming that the network is configured and enabled and the u-boot.ais file 43 is tftp'able. 44 45 U-Boot > sf probe 0 46 U-Boot > sf erase 0 +320000 47 U-Boot > tftp u-boot.ais 48 U-Boot > sf write c0700000 0 $filesize 49 50 Flashing the images to NAND 51 =========================== 52 The AIS image can be written to NAND using the u-boot "nand" commands. 53 54 Example: 55 56 OMAPL138_LCDK requires the AIS image to be written to the second block of 57 the NAND flash. 58 59 From the "nand info" command we see that the second block would start at 60 offset 0x20000: 61 62 U-Boot > nand info 63 sector size 128 KiB (0x20000) 64 Page size 2048 b 65 66 From the tftp command we see that we need to copy 0x74908 bytes from 67 memory address 0xc0700000 (0x75000 if we align a page of 2048): 68 69 U-Boot > tftp u-boot.ais 70 Load address: 0xc0700000 71 Bytes transferred = 477448 (74908 hex) 72 73 The commands to write the image from memory to NAND would be: 74 75 U-Boot > nand erase 0x20000 0x75000 76 U-Boot > nand write 0xc0700000 0x20000 0x75000 77 78 Alternatively, MTD partitions may be defined. Using "mtdparts" to 79 conveniently have a bootloader partition starting at the second block 80 (offset 0x20000): 81 82 setenv mtdids nand0=davinci_nand.0 83 setenv mtdparts mtdparts=davinci_nand.0:128k(bootenv),2m(bootloader) 84 85 In this case the commands would be simplified to: 86 87 U-Boot > tftp u-boot.ais 88 U-Boot > nand erase.part bootloader 89 U-Boot > nand write 0xc0700000 bootloader 90 91 Flashing the images to MMC 92 ========================== 93 If the boot pins are set to boot from mmc, the RBL will try to load the 94 next boot stage form the first couple of sectors of an external mmc card. 95 As sector 0 is usually used for storing the partition information, the 96 AIS image should be written at least after the first sector, but before the 97 first partition begins. (e.g: make sure to leave at least 500KB of unallocated 98 space at the start of the mmc when creating the partitions) 99 100 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR is used by SPL, and should 101 point to the sector were the u-boot image is located. (eg. After SPL) 102 103 There are 2 ways to copy the AIS image to the mmc card: 104 105 1 - Using the TI tool "uflash" 106 $ uflash -d /dev/mmcblk0 -b ./u-boot.ais -p OMAPL138 -vv 107 108 2 - using the "dd" command 109 $ dd if=u-boot.ais of=/dev/mmcblk0 seek=117 bs=512 conv=fsync 110 111 uflash writes the AIS image at offset 117. For compatibility with uflash, 112 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR is set to take into account this 113 offset, and the dd command is adjusted accordingly. 114 115 Recovery 116 ======== 117 118 In the case of a "bricked" board, you need to use the TI tools found 119 here[1] to write the u-boot.ais file. An example of recovering to the SPI 120 flash of an AM1808 would be: 121 122 $ mono sfh_OMAP-L138.exe -targetType AM1808 -p /dev/ttyUSB0 \ 123 -flash_noubl /path/to/u-boot.ais 124 125 For other target types and flash locations: 126 127 $ mono sfh_OMAP-L138.exe -h 128 129 Links 130 ===== 131 [1] 132 http://processors.wiki.ti.com/index.php/Serial_Boot_and_Flash_Loading_Utility_for_OMAP-L138 133
