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diff --git a/doc/board/ti/am335x_evm.rst b/doc/board/ti/am335x_evm.rst new file mode 100644 index 00000000000..51c11a3e51f --- /dev/null +++ b/doc/board/ti/am335x_evm.rst @@ -0,0 +1,227 @@ +.. SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause +.. sectionauthor:: Tom Rini <trini@konsulko.com> + +Summary +======= + +This document covers various features of the 'am335x_evm' build, and some of +the related build targets (am335x_evm_uartN, etc). + +Hardware +-------- + +The binary produced by this board supports, based on parsing of the EEPROM +documented in TI's reference designs: +* AM335x GP EVM +* AM335x EVM SK +* Beaglebone White +* Beaglebone Black + +Customization +------------- + +Given that all of the above boards are reference platforms (and the +Beaglebone platforms are OSHA), it is likely that this platform code and +configuration will be used as the basis of a custom platform. It is +worth noting that aside from things such as NAND or MMC only being +required if a custom platform makes use of these blocks, the following +are required, depending on design: + +* GPIO is only required if DDR3 power is controlled in a way similar to EVM SK +* SPI is only required for SPI flash, or exposing the SPI bus. + +The following blocks are required: + +* I2C, to talk with the PMIC and ensure that we do not run afoul of + errata 1.0.24. + +When removing options as part of customization, +CONFIG_EXTRA_ENV_SETTINGS will need additional care to update for your +needs and to remove no longer relevant options as in some cases we +define additional text blocks (such as for NAND or DFU strings). Also +note that all of the SPL options are grouped together, rather than with +the IP blocks, so both areas will need their choices updated to reflect +the custom design. + +NAND +---- + +The AM335x GP EVM ships with a 256MiB NAND available in most profiles. In +this example to program the NAND we assume that an SD card has been +inserted with the files to write in the first SD slot and that mtdparts +have been configured correctly for the board. All images are first loaded +into memory, then written to NAND. + +Step-1: Building u-boot for NAND boot + Set following CONFIGxx options for NAND device. + CONFIG_SYS_NAND_PAGE_SIZE number of main bytes in NAND page + CONFIG_SYS_NAND_OOBSIZE number of OOB bytes in NAND page + CONFIG_SYS_NAND_BLOCK_SIZE number of bytes in NAND erase-block + CONFIG_SYS_NAND_ECCPOS ECC map for NAND page + CONFIG_NAND_OMAP_ECCSCHEME (refer doc/README.nand) + +Step-2: Flashing NAND via MMC/SD + +.. code-block:: text + + # select BOOTSEL to MMC/SD boot and boot from MMC/SD card + U-Boot # mmc rescan + # erase flash + U-Boot # nand erase.chip + U-Boot # env default -f -a + U-Boot # saveenv + # flash MLO. Redundant copies of MLO are kept for failsafe + U-Boot # load mmc 0 0x82000000 MLO + U-Boot # nand write 0x82000000 0x00000 0x20000 + U-Boot # nand write 0x82000000 0x20000 0x20000 + U-Boot # nand write 0x82000000 0x40000 0x20000 + U-Boot # nand write 0x82000000 0x60000 0x20000 + # flash u-boot.img + U-Boot # load mmc 0 0x82000000 u-boot.img + U-Boot # nand write 0x82000000 0x80000 0x60000 + # flash kernel image + U-Boot # load mmc 0 0x82000000 uImage + U-Boot # nand write 0x82000000 ${nandsrcaddr} ${nandimgsize} + # flash filesystem image + U-Boot # load mmc 0 0x82000000 filesystem.img + U-Boot # nand write 0x82000000 ${loadaddress} 0x300000 + +Step-3: Set BOOTSEL pin to select NAND boot, and POR the device. + The device should boot from images flashed on NAND device. + +NOR +--- + +The Beaglebone White can be equipped with a "memory cape" that in turn can +have a NOR module plugged into it. In this case it is then possible to +program and boot from NOR. Note that due to how U-Boot is designed we +must build a specific version of U-Boot that knows we have NOR flash. This +build is named 'am335x_evm_nor'. Further, we have a 'am335x_evm_norboot' +build that will assume that the environment is on NOR rather than NAND. In +the following example we assume that and SD card has been populated with +MLO and u-boot.img from a 'am335x_evm_nor' build and also contains the +'u-boot.bin' from a 'am335x_evm_norboot' build. When booting from NOR, a +binary must be written to the start of NOR, with no header or similar +prepended. In the following example we use a size of 512KiB (0x80000) +as that is how much space we set aside before the environment, as per +the config file. + +.. code-block:: text + + U-Boot # mmc rescan + U-Boot # load mmc 0 ${loadaddr} u-boot.bin + U-Boot # protect off 08000000 +80000 + U-Boot # erase 08000000 +80000 + U-Boot # cp.b ${loadaddr} 08000000 ${filesize} + +Falcon Mode +----------- + +The default build includes "Falcon Mode" (see doc/README.falcon) via NAND, +eMMC (or raw SD cards) and FAT SD cards. Our default behavior currently is +to read a 'c' on the console while in SPL at any point prior to loading the +OS payload (so as soon as possible) to opt to booting full U-Boot. Also +note that while one can program Falcon Mode "in place" great care needs to +be taken by the user to not 'brick' their setup. As these are all eval +boards with multiple boot methods, recovery should not be an issue in this +worst-case however. + +Falcon Mode: eMMC +----------------- + +The recommended layout in this case is: + +.. code-block:: text + + MMC BLOCKS |--------------------------------| LOCATION IN BYTES + 0x0000 - 0x007F : MBR or GPT table : 0x000000 - 0x020000 + 0x0080 - 0x00FF : ARGS or FDT file : 0x010000 - 0x020000 + 0x0100 - 0x01FF : SPL.backup1 (first copy used) : 0x020000 - 0x040000 + 0x0200 - 0x02FF : SPL.backup2 (second copy used) : 0x040000 - 0x060000 + 0x0300 - 0x06FF : U-Boot : 0x060000 - 0x0e0000 + 0x0700 - 0x08FF : U-Boot Env + Redundant : 0x0e0000 - 0x120000 + 0x0900 - 0x28FF : Kernel : 0x120000 - 0x520000 + +Note that when we run 'spl export' it will prepare to boot the kernel. +This includes relocation of the uImage from where we loaded it to the entry +point defined in the header. As these locations overlap by default, it +would leave us with an image that if written to MMC will not boot, so +instead of using the loadaddr variable we use 0x81000000 in the following +example. In this example we are loading from the network, for simplicity, +and assume a valid partition table already exists and 'mmc dev' has already +been run to select the correct device. Also note that if you previously +had a FAT partition (such as on a Beaglebone Black) it is not enough to +write garbage into the area, you must delete it from the partition table +first. + +.. code-block:: text + + # Ensure we are able to talk with this mmc device + U-Boot # mmc rescan + U-Boot # tftp 81000000 am335x/MLO + # Write to two of the backup locations ROM uses + U-Boot # mmc write 81000000 100 100 + U-Boot # mmc write 81000000 200 100 + # Write U-Boot to the location set in the config + U-Boot # tftp 81000000 am335x/u-boot.img + U-Boot # mmc write 81000000 300 400 + # Load kernel and device tree into memory, perform export + U-Boot # tftp 81000000 am335x/uImage + U-Boot # run findfdt + U-Boot # tftp ${fdtaddr} am335x/${fdtfile} + U-Boot # run mmcargs + U-Boot # spl export fdt 81000000 - ${fdtaddr} + # Write the updated device tree to MMC + U-Boot # mmc write ${fdtaddr} 80 80 + # Write the uImage to MMC + U-Boot # mmc write 81000000 900 2000 + +Falcon Mode: FAT SD cards +------------------------- + +In this case the additional file is written to the filesystem. In this +example we assume that the uImage and device tree to be used are already on +the FAT filesystem (only the uImage MUST be for this to function +afterwards) along with a Falcon Mode aware MLO and the FAT partition has +already been created and marked bootable: + +.. code-block:: text + + U-Boot # mmc rescan + # Load kernel and device tree into memory, perform export + U-Boot # load mmc 0:1 ${loadaddr} uImage + U-Boot # run findfdt + U-Boot # load mmc 0:1 ${fdtaddr} ${fdtfile} + U-Boot # run mmcargs + U-Boot # spl export fdt ${loadaddr} - ${fdtaddr} + +This will print a number of lines and then end with something like: + +.. code-block:: text + + Using Device Tree in place at 80f80000, end 80f85928 + Using Device Tree in place at 80f80000, end 80f88928 + +So then you: + +.. code-block:: text + + U-Boot # fatwrite mmc 0:1 0x80f80000 args 8928 + +Falcon Mode: NAND +----------------- + +In this case the additional data is written to another partition of the +NAND. In this example we assume that the uImage and device tree to be are +already located on the NAND somewhere (such as filesystem or mtd partition) +along with a Falcon Mode aware MLO written to the correct locations for +booting and mtdparts have been configured correctly for the board: + +.. code-block:: text + + U-Boot # nand read ${loadaddr} kernel + U-Boot # load nand rootfs ${fdtaddr} /boot/am335x-evm.dtb + U-Boot # run nandargs + U-Boot # spl export fdt ${loadaddr} - ${fdtaddr} + U-Boot # nand erase.part u-boot-spl-os + U-Boot # nand write ${fdtaddr} u-boot-spl-os |