1 .. SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
2 .. sectionauthor:: Tom Rini <trini@konsulko.com>
7 This document covers various features of the `am335x_evm` default
8 configuration, some of the related defconfigs, and how to enable hardware
9 features not present by default in the defconfigs.
14 The binary produced by this board supports, based on parsing of the EEPROM
15 documented in TI's reference designs:
18 * The Beaglebone family of designs
23 Given that all of the above boards are reference platforms (and the
24 Beaglebone platforms are OSHA), it is likely that this platform code and
25 configuration will be used as the basis of a custom platform. It is
26 worth noting that aside from things such as NAND or MMC only being
27 required if a custom platform makes use of these blocks, the following
28 are required, depending on design:
30 * GPIO is only required if DDR3 power is controlled in a way similar to EVM SK
31 * SPI is only required for SPI flash, or exposing the SPI bus.
33 The following blocks are required:
35 * I2C, to talk with the PMIC and ensure that we do not run afoul of
38 When removing options as part of customization, note that you will likely need
39 to look at both `include/configs/am335x_evm.h`,
40 `include/configs/ti_am335x_common.h` and `include/configs/am335x_evm.h` as the
41 migration to Kconfig is not yet complete.
46 The AM335x GP EVM ships with a 256MiB NAND available in most profiles. In
47 this example to program the NAND we assume that an SD card has been
48 inserted with the files to write in the first SD slot and that mtdparts
49 have been configured correctly for the board. All images are first loaded
50 into memory, then written to NAND.
52 Step-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)
60 Step-2: Flashing NAND via MMC/SD
64 # select BOOTSEL to MMC/SD boot and boot from MMC/SD card
67 U-Boot # nand erase.chip
68 U-Boot # env default -f -a
70 # flash MLO. Redundant copies of MLO are kept for failsafe
71 U-Boot # load mmc 0 0x82000000 MLO
72 U-Boot # nand write 0x82000000 0x00000 0x20000
73 U-Boot # nand write 0x82000000 0x20000 0x20000
74 U-Boot # nand write 0x82000000 0x40000 0x20000
75 U-Boot # nand write 0x82000000 0x60000 0x20000
77 U-Boot # load mmc 0 0x82000000 u-boot.img
78 U-Boot # nand write 0x82000000 0x80000 0x60000
80 U-Boot # load mmc 0 0x82000000 uImage
81 U-Boot # nand write 0x82000000 ${nandsrcaddr} ${nandimgsize}
82 # flash filesystem image
83 U-Boot # load mmc 0 0x82000000 filesystem.img
84 U-Boot # nand write 0x82000000 ${loadaddress} 0x300000
86 Step-3: Set BOOTSEL pin to select NAND boot, and POR the device.
87 The device should boot from images flashed on NAND device.
93 The default build includes "Falcon Mode" (see doc/README.falcon) via NAND,
94 eMMC (or raw SD cards) and FAT SD cards. Our default behavior currently is
95 to read a 'c' on the console while in SPL at any point prior to loading the
96 OS payload (so as soon as possible) to opt to booting full U-Boot. Also
97 note that while one can program Falcon Mode "in place" great care needs to
98 be taken by the user to not 'brick' their setup. As these are all eval
99 boards with multiple boot methods, recovery should not be an issue in this
105 The recommended layout in this case is:
109 MMC BLOCKS |--------------------------------| LOCATION IN BYTES
110 0x0000 - 0x007F : MBR or GPT table : 0x000000 - 0x020000
111 0x0080 - 0x00FF : ARGS or FDT file : 0x010000 - 0x020000
112 0x0100 - 0x01FF : SPL.backup1 (first copy used) : 0x020000 - 0x040000
113 0x0200 - 0x02FF : SPL.backup2 (second copy used) : 0x040000 - 0x060000
114 0x0300 - 0x06FF : U-Boot : 0x060000 - 0x0e0000
115 0x0700 - 0x08FF : U-Boot Env + Redundant : 0x0e0000 - 0x120000
116 0x0900 - 0x28FF : Kernel : 0x120000 - 0x520000
118 Note that when we run 'spl export' it will prepare to boot the kernel.
119 This includes relocation of the uImage from where we loaded it to the entry
120 point defined in the header. As these locations overlap by default, it
121 would leave us with an image that if written to MMC will not boot, so
122 instead of using the loadaddr variable we use 0x81000000 in the following
123 example. In this example we are loading from the network, for simplicity,
124 and assume a valid partition table already exists and 'mmc dev' has already
125 been run to select the correct device. Also note that if you previously
126 had a FAT partition (such as on a Beaglebone Black) it is not enough to
127 write garbage into the area, you must delete it from the partition table
132 # Ensure we are able to talk with this mmc device
134 U-Boot # tftp 81000000 am335x/MLO
135 # Write to two of the backup locations ROM uses
136 U-Boot # mmc write 81000000 100 100
137 U-Boot # mmc write 81000000 200 100
138 # Write U-Boot to the location set in the config
139 U-Boot # tftp 81000000 am335x/u-boot.img
140 U-Boot # mmc write 81000000 300 400
141 # Load kernel and device tree into memory, perform export
142 U-Boot # tftp 81000000 am335x/uImage
144 U-Boot # tftp ${fdtaddr} am335x/${fdtfile}
146 U-Boot # spl export fdt 81000000 - ${fdtaddr}
147 # Write the updated device tree to MMC
148 U-Boot # mmc write ${fdtaddr} 80 80
149 # Write the uImage to MMC
150 U-Boot # mmc write 81000000 900 2000
152 Falcon Mode: FAT SD cards
153 -------------------------
155 In this case the additional file is written to the filesystem. In this
156 example we assume that the uImage and device tree to be used are already on
157 the FAT filesystem (only the uImage MUST be for this to function
158 afterwards) along with a Falcon Mode aware MLO and the FAT partition has
159 already been created and marked bootable:
164 # Load kernel and device tree into memory, perform export
165 U-Boot # load mmc 0:1 ${loadaddr} uImage
167 U-Boot # load mmc 0:1 ${fdtaddr} ${fdtfile}
169 U-Boot # spl export fdt ${loadaddr} - ${fdtaddr}
171 This will print a number of lines and then end with something like:
175 Using Device Tree in place at 80f80000, end 80f85928
176 Using Device Tree in place at 80f80000, end 80f88928
182 U-Boot # fatwrite mmc 0:1 0x80f80000 args 8928
187 In this case the additional data is written to another partition of the
188 NAND. In this example we assume that the uImage and device tree to be are
189 already located on the NAND somewhere (such as filesystem or mtd partition)
190 along with a Falcon Mode aware MLO written to the correct locations for
191 booting and mtdparts have been configured correctly for the board:
195 U-Boot # nand read ${loadaddr} kernel
196 U-Boot # load nand rootfs ${fdtaddr} /boot/am335x-evm.dtb
197 U-Boot # run nandargs
198 U-Boot # spl export fdt ${loadaddr} - ${fdtaddr}
199 U-Boot # nand erase.part u-boot-spl-os
200 U-Boot # nand write ${fdtaddr} u-boot-spl-os