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README
1Summary 2======= 3 4This document covers various features of the 'am335x_evm' build, and some of 5the related build targets (am335x_evm_uartN, etc). 6 7Hardware 8======== 9 10The binary produced by this board supports, based on parsing of the EEPROM 11documented in TI's reference designs: 12- AM335x GP EVM 13- AM335x EVM SK 14- Beaglebone White 15- Beaglebone Black 16 17Customization 18============= 19 20Given that all of the above boards are reference platforms (and the 21Beaglebone platforms are OSHA), it is likely that this platform code and 22configuration will be used as the basis of a custom platform. It is 23worth noting that aside from things such as NAND or MMC only being 24required if a custom platform makes use of these blocks, the following 25are required, depending on design: 26 27- GPIO is only required if DDR3 power is controlled in a way similar to 28 EVM SK 29- SPI is only required for SPI flash, or exposing the SPI bus. 30 31The following blocks are required: 32- I2C, to talk with the PMIC and ensure that we do not run afoul of 33 errata 1.0.24. 34 35When removing options as part of customization, 36CONFIG_EXTRA_ENV_SETTINGS will need additional care to update for your 37needs and to remove no longer relevant options as in some cases we 38define additional text blocks (such as for NAND or DFU strings). Also 39note that all of the SPL options are grouped together, rather than with 40the IP blocks, so both areas will need their choices updated to reflect 41the custom design. 42 43NAND 44==== 45 46The AM335x GP EVM ships with a 256MiB NAND available in most profiles. In 47this example to program the NAND we assume that an SD card has been 48inserted with the files to write in the first SD slot and that mtdparts 49have been configured correctly for the board. All images are first loaded 50into memory, then written to NAND. 51 52Step-1: Building u-boot for NAND boot 53 Set following CONFIGxx options for NAND device. 54 CONFIG_SYS_NAND_PAGE_SIZE number of main bytes in NAND page 55 CONFIG_SYS_NAND_OOBSIZE number of OOB bytes in NAND page 56 CONFIG_SYS_NAND_BLOCK_SIZE number of bytes in NAND erase-block 57 CONFIG_SYS_NAND_ECCPOS ECC map for NAND page 58 CONFIG_NAND_OMAP_ECCSCHEME (refer doc/README.nand) 59 60Step-2: Flashing NAND via MMC/SD 61 # select BOOTSEL to MMC/SD boot and boot from MMC/SD card 62 U-Boot # mmc rescan 63 # erase flash 64 U-Boot # nand erase.chip 65 U-Boot # env default -f -a 66 U-Boot # saveenv 67 # flash MLO. Redundant copies of MLO are kept for failsafe 68 U-Boot # load mmc 0 0x82000000 MLO 69 U-Boot # nand write 0x82000000 0x00000 0x20000 70 U-Boot # nand write 0x82000000 0x20000 0x20000 71 U-Boot # nand write 0x82000000 0x40000 0x20000 72 U-Boot # nand write 0x82000000 0x60000 0x20000 73 # flash u-boot.img 74 U-Boot # load mmc 0 0x82000000 u-boot.img 75 U-Boot # nand write 0x82000000 0x80000 0x60000 76 # flash kernel image 77 U-Boot # load mmc 0 0x82000000 uImage 78 U-Boot # nand write 0x82000000 ${nandsrcaddr} ${nandimgsize} 79 # flash filesystem image 80 U-Boot # load mmc 0 0x82000000 filesystem.img 81 U-Boot # nand write 0x82000000 ${loadaddress} 0x300000 82 83Step-3: Set BOOTSEL pin to select NAND boot, and POR the device. 84 The device should boot from images flashed on NAND device. 85 86NOR 87=== 88 89The Beaglebone White can be equipped with a "memory cape" that in turn can 90have a NOR module plugged into it. In this case it is then possible to 91program and boot from NOR. Note that due to how U-Boot is designed we 92must build a specific version of U-Boot that knows we have NOR flash. This 93build is named 'am335x_evm_nor'. Further, we have a 'am335x_evm_norboot' 94build that will assume that the environment is on NOR rather than NAND. In 95the following example we assume that and SD card has been populated with 96MLO and u-boot.img from a 'am335x_evm_nor' build and also contains the 97'u-boot.bin' from a 'am335x_evm_norboot' build. When booting from NOR, a 98binary must be written to the start of NOR, with no header or similar 99prepended. In the following example we use a size of 512KiB (0x80000) 100as that is how much space we set aside before the environment, as per 101the config file. 102 103U-Boot # mmc rescan 104U-Boot # load mmc 0 ${loadaddr} u-boot.bin 105U-Boot # protect off 08000000 +80000 106U-Boot # erase 08000000 +80000 107U-Boot # cp.b ${loadaddr} 08000000 ${filesize} 108 109Falcon Mode 110=========== 111 112The default build includes "Falcon Mode" (see doc/README.falcon) via NAND, 113eMMC (or raw SD cards) and FAT SD cards. Our default behavior currently is 114to read a 'c' on the console while in SPL at any point prior to loading the 115OS payload (so as soon as possible) to opt to booting full U-Boot. Also 116note that while one can program Falcon Mode "in place" great care needs to 117be taken by the user to not 'brick' their setup. As these are all eval 118boards with multiple boot methods, recovery should not be an issue in this 119worst-case however. 120 121Falcon Mode: eMMC 122================= 123 124The recommended layout in this case is: 125 126MMC BLOCKS |--------------------------------| LOCATION IN BYTES 1270x0000 - 0x007F : MBR or GPT table : 0x000000 - 0x020000 1280x0080 - 0x00FF : ARGS or FDT file : 0x010000 - 0x020000 1290x0100 - 0x01FF : SPL.backup1 (first copy used) : 0x020000 - 0x040000 1300x0200 - 0x02FF : SPL.backup2 (second copy used) : 0x040000 - 0x060000 1310x0300 - 0x06FF : U-Boot : 0x060000 - 0x0e0000 1320x0700 - 0x08FF : U-Boot Env + Redundant : 0x0e0000 - 0x120000 1330x0900 - 0x28FF : Kernel : 0x120000 - 0x520000 134 135Note that when we run 'spl export' it will prepare to boot the kernel. 136This includes relocation of the uImage from where we loaded it to the entry 137point defined in the header. As these locations overlap by default, it 138would leave us with an image that if written to MMC will not boot, so 139instead of using the loadaddr variable we use 0x81000000 in the following 140example. In this example we are loading from the network, for simplicity, 141and assume a valid partition table already exists and 'mmc dev' has already 142been run to select the correct device. Also note that if you previously 143had a FAT partition (such as on a Beaglebone Black) it is not enough to 144write garbage into the area, you must delete it from the partition table 145first. 146 147# Ensure we are able to talk with this mmc device 148U-Boot # mmc rescan 149U-Boot # tftp 81000000 am335x/MLO 150# Write to two of the backup locations ROM uses 151U-Boot # mmc write 81000000 100 100 152U-Boot # mmc write 81000000 200 100 153# Write U-Boot to the location set in the config 154U-Boot # tftp 81000000 am335x/u-boot.img 155U-Boot # mmc write 81000000 300 400 156# Load kernel and device tree into memory, perform export 157U-Boot # tftp 81000000 am335x/uImage 158U-Boot # run findfdt 159U-Boot # tftp ${fdtaddr} am335x/${fdtfile} 160U-Boot # run mmcargs 161U-Boot # spl export fdt 81000000 - ${fdtaddr} 162# Write the updated device tree to MMC 163U-Boot # mmc write ${fdtaddr} 80 80 164# Write the uImage to MMC 165U-Boot # mmc write 81000000 900 2000 166 167Falcon Mode: FAT SD cards 168========================= 169 170In this case the additional file is written to the filesystem. In this 171example we assume that the uImage and device tree to be used are already on 172the FAT filesystem (only the uImage MUST be for this to function 173afterwards) along with a Falcon Mode aware MLO and the FAT partition has 174already been created and marked bootable: 175 176U-Boot # mmc rescan 177# Load kernel and device tree into memory, perform export 178U-Boot # load mmc 0:1 ${loadaddr} uImage 179U-Boot # run findfdt 180U-Boot # load mmc 0:1 ${fdtaddr} ${fdtfile} 181U-Boot # run mmcargs 182U-Boot # spl export fdt ${loadaddr} - ${fdtaddr} 183 184This will print a number of lines and then end with something like: 185 Using Device Tree in place at 80f80000, end 80f85928 186 Using Device Tree in place at 80f80000, end 80f88928 187So then you: 188 189U-Boot # fatwrite mmc 0:1 0x80f80000 args 8928 190 191Falcon Mode: NAND 192================= 193 194In this case the additional data is written to another partition of the 195NAND. In this example we assume that the uImage and device tree to be are 196already located on the NAND somewhere (such as filesystem or mtd partition) 197along with a Falcon Mode aware MLO written to the correct locations for 198booting and mtdparts have been configured correctly for the board: 199 200U-Boot # nand read ${loadaddr} kernel 201U-Boot # load nand rootfs ${fdtaddr} /boot/am335x-evm.dtb 202U-Boot # run nandargs 203U-Boot # spl export fdt ${loadaddr} - ${fdtaddr} 204U-Boot # nand erase.part u-boot-spl-os 205U-Boot # nand write ${fdtaddr} u-boot-spl-os 206