--- /dev/null
+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
+ # 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 equiped 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 architectured 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.
+
+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:
+
+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.
+
+# 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:
+
+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:
+ Using Device Tree in place at 80f80000, end 80f85928
+ Using Device Tree in place at 80f80000, end 80f88928
+So then you:
+
+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 fileystem 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:
+
+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
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