doc/README.imx6

   1 U-Boot for Freescale i.MX6
   2
   3 This file contains information for the port of U-Boot to the Freescale i.MX6
   4 SoC.
   5
   6 1. CONVENTIONS FOR FUSE ASSIGNMENTS
   7 -----------------------------------
   8
   9 1.1 MAC Address: It is stored in fuse bank 4, with the 32 lsbs in word 2 and the
  10     16 msbs in word 3.
  11
  12 Example:
  13
  14 For reading the MAC address fuses on a MX6Q:
  15
  16 - The MAC address is stored in two fuse addresses (the fuse addresses are
  17 described in the Fusemap Descriptions table from the mx6q Reference Manual):
  18
  19 0x620[31:0] - MAC_ADDR[31:0]
  20 0x630[15:0] - MAC_ADDR[47:32]
  21
  22 In order to use the fuse API, we need to pass the bank and word values, which
  23 are calculated as below:
  24
  25 Fuse address for the lower MAC address: 0x620
  26 Base address for the fuses: 0x400
  27
  28 (0x620 - 0x400)/0x10 = 0x22 = 34 decimal
  29
  30 As the fuses are arranged in banks of 8 words:
  31
  32 34 / 8 = 4 and the remainder is 2, so in this case:
  33
  34 bank = 4
  35 word = 2
  36
  37 And the U-boot command would be:
  38
  39 => fuse read 4 2
  40 Reading bank 4:
  41
  42 Word 0x00000002: 9f027772
  43
  44 Doing the same for the upper MAC address:
  45
  46 Fuse address for the upper MAC address: 0x630
  47 Base address for the fuses: 0x400
  48
  49 (0x630 - 0x400)/0x10 = 0x23 = 35 decimal
  50
  51 As the fuses are arranged in banks of 8 words:
  52
  53 35 / 8 = 4 and the remainder is 3, so in this case:
  54
  55 bank = 4
  56 word = 3
  57
  58 And the U-boot command would be:
  59
  60 => fuse read 4 3
  61 Reading bank 4:
  62
  63 Word 0x00000003: 00000004
  64
  65 ,which matches the ethaddr value:
  66 => echo ${ethaddr}
  67 00:04:9f:02:77:72
  68
  69 Some other useful hints:
  70
  71 - The 'bank' and 'word' numbers can be easily obtained from the mx6 Reference
  72 Manual. For the mx6quad case, please check the "46.5 OCOTP Memory Map/Register
  73 Definition" from the "i.MX 6Dual/6Quad Applications Processor Reference Manual,
  74 Rev. 1, 04/2013" document. For example, for the MAC fuses we have:
  75
  76 Address:
  77 21B_C620        Value of OTP Bank4 Word2 (MAC Address)(OCOTP_MAC0)
  78
  79 21B_C630        Value of OTP Bank4 Word3 (MAC Address)(OCOTP_MAC1)
  80
  81 - The command '=> fuse read 4 2 2' reads the whole MAC addresses at once:
  82
  83 => fuse read 4 2 2
  84 Reading bank 4:
  85
  86 Word 0x00000002: 9f027772 00000004
  87
  88 2. Using imx_usb_loader for first install with SPL
  89 --------------------------------------------------
  90
  91 imx_usb_loader is a very nice tool by BoundaryDevice that
  92 allow to install U-Boot without a JTAG debugger, using
  93 the USB boot mode as described in the manual. It is
  94 a replacement for Freescale's MFGTOOLS.
  95
  96 The sources can be found here:
  97
  98         https://github.com/boundarydevices/imx_usb_loader.git
  99
 100 Booting in USB mode, the i.MX6 announces itself to the Linux Host as:
 101
 102 Bus 001 Device 111: ID 15a2:0061 Freescale Semiconductor, Inc.
 103
 104 imx_usb_loader is able to download a single file (u-boot.imx)
 105 to the board. For boards without SPL support, it is enough to
 106 issue the command:
 107
 108         sudo ../imx_usb_loader/imx_usb -v u-boot.imx
 109
 110 Getting U-Boot when SPL support is active, it requires
 111 two downloads. imx_usb_loader downloads the SPL into
 112 OCRAM and starts it. SPL will check for a valid u-boot.img, and
 113 because it is not found, it will wait for it using the y-modem
 114 protocol via the console.
 115
 116 A first install is then possible by combining imx_usb_loader with
 117 another tool such as kermit.
 118
 119 sudo ../imx_usb_loader/imx_usb -v SPL
 120 kermit kermit_uboot
 121
 122 and kermit_uboot contains something like this (set line should be adjusted):
 123
 124 set line /dev/ttyUSB1
 125 set speed 115200
 126 SET CARRIER-WATCH OFF
 127 set flow-control none
 128 set handshake none
 129 set prefixing all
 130 set file type bin
 131 set protocol ymodem
 132 send u-boot.img
 133 c
 134
 135 The last "c" command tells kermit (from ckermit package in most distros)
 136 to switch from command line mode to communication mode, and when the
 137 script is finished, the U-Boot prompt is shown in the same shell.