README 7.5 KB

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  1. Summary
  2. =======
  3. This document covers various features of the 'am335x_evm' build, and some of
  4. the related build targets (am335x_evm_uartN, etc).
  5. Hardware
  6. ========
  7. The binary produced by this board supports, based on parsing of the EEPROM
  8. documented in TI's reference designs:
  9. - AM335x GP EVM
  10. - AM335x EVM SK
  11. - Beaglebone White
  12. - Beaglebone Black
  13. Customization
  14. =============
  15. Given that all of the above boards are reference platforms (and the
  16. Beaglebone platforms are OSHA), it is likely that this platform code and
  17. configuration will be used as the basis of a custom platform. It is
  18. worth noting that aside from things such as NAND or MMC only being
  19. required if a custom platform makes use of these blocks, the following
  20. are required, depending on design:
  21. - GPIO is only required if DDR3 power is controlled in a way similar to
  22. EVM SK
  23. - SPI is only required for SPI flash, or exposing the SPI bus.
  24. The following blocks are required:
  25. - I2C, to talk with the PMIC and ensure that we do not run afoul of
  26. errata 1.0.24.
  27. When removing options as part of customization,
  28. CONFIG_EXTRA_ENV_SETTINGS will need additional care to update for your
  29. needs and to remove no longer relevant options as in some cases we
  30. define additional text blocks (such as for NAND or DFU strings). Also
  31. note that all of the SPL options are grouped together, rather than with
  32. the IP blocks, so both areas will need their choices updated to reflect
  33. the custom design.
  34. NAND
  35. ====
  36. The AM335x GP EVM ships with a 256MiB NAND available in most profiles. In
  37. this example to program the NAND we assume that an SD card has been
  38. inserted with the files to write in the first SD slot and that mtdparts
  39. have been configured correctly for the board. As a time saving measure we
  40. load MLO into memory in one location, copy it into the three locatations
  41. that the ROM checks for additional valid copies, then load U-Boot into
  42. memory. We then write that whole section of memory to NAND.
  43. U-Boot # mmc rescan
  44. U-Boot # env default -f -a
  45. U-Boot # nand erase.chip
  46. U-Boot # saveenv
  47. U-Boot # load mmc 0 81000000 MLO
  48. U-Boot # cp.b 81000000 81020000 20000
  49. U-Boot # cp.b 81000000 81040000 20000
  50. U-Boot # cp.b 81000000 81060000 20000
  51. U-Boot # load mmc 0 81080000 u-boot.img
  52. U-Boot # nand write 81000000 0 260000
  53. U-Boot # load mmc 0 ${loadaddr} uImage
  54. U-Boot # nand write ${loadaddr} kernel 500000
  55. NOR
  56. ===
  57. The Beaglebone White can be equiped with a "memory cape" that in turn can
  58. have a NOR module plugged into it. In this case it is then possible to
  59. program and boot from NOR. Note that due to how U-Boot is architectured we
  60. must build a specific version of U-Boot that knows we have NOR flash. This
  61. build is named 'am335x_evm_nor'. Further, we have a 'am335x_evm_norboot'
  62. build that will assume that the environment is on NOR rather than NAND. In
  63. the following example we assume that and SD card has been populated with
  64. MLO and u-boot.img from a 'am335x_evm_nor' build and also contains the
  65. 'u-boot.bin' from a 'am335x_evm_norboot' build. When booting from NOR, a
  66. binary must be written to the start of NOR, with no header or similar
  67. prepended. In the following example we use a size of 512KiB (0x80000)
  68. as that is how much space we set aside before the environment, as per
  69. the config file.
  70. U-Boot # mmc rescan
  71. U-Boot # load mmc 0 ${loadaddr} u-boot.bin
  72. U-Boot # protect off 08000000 +80000
  73. U-Boot # erase 08000000 +80000
  74. U-Boot # cp.b ${loadaddr} 08000000 ${filesize}
  75. Falcon Mode
  76. ===========
  77. The default build includes "Falcon Mode" (see doc/README.falcon) via NAND,
  78. eMMC (or raw SD cards) and FAT SD cards. Our default behavior currently is
  79. to read a 'c' on the console while in SPL at any point prior to loading the
  80. OS payload (so as soon as possible) to opt to booting full U-Boot. Also
  81. note that while one can program Falcon Mode "in place" great care needs to
  82. be taken by the user to not 'brick' their setup. As these are all eval
  83. boards with multiple boot methods, recovery should not be an issue in this
  84. worst-case however.
  85. Falcon Mode: eMMC
  86. =================
  87. The recommended layout in this case is:
  88. MMC BLOCKS |--------------------------------| LOCATION IN BYTES
  89. 0x0000 - 0x007F : MBR or GPT table : 0x000000 - 0x020000
  90. 0x0080 - 0x00FF : ARGS or FDT file : 0x010000 - 0x020000
  91. 0x0100 - 0x01FF : SPL.backup1 (first copy used) : 0x020000 - 0x040000
  92. 0x0200 - 0x02FF : SPL.backup2 (second copy used) : 0x040000 - 0x060000
  93. 0x0300 - 0x06FF : U-Boot : 0x060000 - 0x0e0000
  94. 0x0700 - 0x08FF : U-Boot Env + Redundant : 0x0e0000 - 0x120000
  95. 0x0900 - 0x28FF : Kernel : 0x120000 - 0x520000
  96. Note that when we run 'spl export' it will prepare to boot the kernel.
  97. This includes relocation of the uImage from where we loaded it to the entry
  98. point defined in the header. As these locations overlap by default, it
  99. would leave us with an image that if written to MMC will not boot, so
  100. instead of using the loadaddr variable we use 0x81000000 in the following
  101. example. In this example we are loading from the network, for simplicity,
  102. and assume a valid partition table already exists and 'mmc dev' has already
  103. been run to select the correct device. Also note that if you previously
  104. had a FAT partition (such as on a Beaglebone Black) it is not enough to
  105. write garbage into the area, you must delete it from the partition table
  106. first.
  107. # Ensure we are able to talk with this mmc device
  108. U-Boot # mmc rescan
  109. U-Boot # tftp 81000000 am335x/MLO
  110. # Write to two of the backup locations ROM uses
  111. U-Boot # mmc write 81000000 100 100
  112. U-Boot # mmc write 81000000 200 100
  113. # Write U-Boot to the location set in the config
  114. U-Boot # tftp 81000000 am335x/u-boot.img
  115. U-Boot # mmc write 81000000 300 400
  116. # Load kernel and device tree into memory, perform export
  117. U-Boot # tftp 81000000 am335x/uImage
  118. U-Boot # run findfdt
  119. U-Boot # tftp ${fdtaddr} am335x/${fdtfile}
  120. U-Boot # run mmcargs
  121. U-Boot # spl export fdt 81000000 - ${fdtaddr}
  122. # Write the updated device tree to MMC
  123. U-Boot # mmc write ${fdtaddr} 80 80
  124. # Write the uImage to MMC
  125. U-Boot # mmc write 81000000 900 2000
  126. Falcon Mode: FAT SD cards
  127. =========================
  128. In this case the additional file is written to the filesystem. In this
  129. example we assume that the uImage and device tree to be used are already on
  130. the FAT filesystem (only the uImage MUST be for this to function
  131. afterwards) along with a Falcon Mode aware MLO and the FAT partition has
  132. already been created and marked bootable:
  133. U-Boot # mmc rescan
  134. # Load kernel and device tree into memory, perform export
  135. U-Boot # load mmc 0:1 ${loadaddr} uImage
  136. U-Boot # run findfdt
  137. U-Boot # load mmc 0:1 ${fdtaddr} ${fdtfile}
  138. U-Boot # run mmcargs
  139. U-Boot # spl export fdt ${loadaddr} - ${fdtaddr}
  140. This will print a number of lines and then end with something like:
  141. Using Device Tree in place at 80f80000, end 80f85928
  142. Using Device Tree in place at 80f80000, end 80f88928
  143. So then you:
  144. U-Boot # fatwrite mmc 0:1 0x80f80000 args 8928
  145. Falcon Mode: NAND
  146. =================
  147. In this case the additional data is written to another partition of the
  148. NAND. In this example we assume that the uImage and device tree to be are
  149. already located on the NAND somewhere (such as fileystem or mtd partition)
  150. along with a Falcon Mode aware MLO written to the correct locations for
  151. booting and mtdparts have been configured correctly for the board:
  152. U-Boot # nand read ${loadaddr} kernel
  153. U-Boot # load nand rootfs ${fdtaddr} /boot/am335x-evm.dtb
  154. U-Boot # run nandargs
  155. U-Boot # spl export fdt ${loadaddr} - ${fdtaddr}
  156. U-Boot # nand erase.part u-boot-spl-os
  157. U-Boot # nand write ${fdtaddr} u-boot-spl-os