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[15:0].
  11     For i.MX6SX and i.MX6UL, they have two MAC addresses. The second MAC address
  12     is stored in fuse bank 4, with the 16 lsb in word 3[31:16] and the 32 msbs in
  13     word 4.
  14
  15 Example:
  16
  17 For reading the MAC address fuses on a MX6Q:
  18
  19 - The MAC address is stored in two fuse addresses (the fuse addresses are
  20 described in the Fusemap Descriptions table from the mx6q Reference Manual):
  21
  22 0x620[31:0] - MAC_ADDR[31:0]
  23 0x630[15:0] - MAC_ADDR[47:32]
  24
  25 In order to use the fuse API, we need to pass the bank and word values, which
  26 are calculated as below:
  27
  28 Fuse address for the lower MAC address: 0x620
  29 Base address for the fuses: 0x400
  30
  31 (0x620 - 0x400)/0x10 = 0x22 = 34 decimal
  32
  33 As the fuses are arranged in banks of 8 words:
  34
  35 34 / 8 = 4 and the remainder is 2, so in this case:
  36
  37 bank = 4
  38 word = 2
  39
  40 And the U-Boot command would be:
  41
  42 => fuse read 4 2
  43 Reading bank 4:
  44
  45 Word 0x00000002: 9f027772
  46
  47 Doing the same for the upper MAC address:
  48
  49 Fuse address for the upper MAC address: 0x630
  50 Base address for the fuses: 0x400
  51
  52 (0x630 - 0x400)/0x10 = 0x23 = 35 decimal
  53
  54 As the fuses are arranged in banks of 8 words:
  55
  56 35 / 8 = 4 and the remainder is 3, so in this case:
  57
  58 bank = 4
  59 word = 3
  60
  61 And the U-Boot command would be:
  62
  63 => fuse read 4 3
  64 Reading bank 4:
  65
  66 Word 0x00000003: 00000004
  67
  68 ,which matches the ethaddr value:
  69 => echo ${ethaddr}
  70 00:04:9f:02:77:72
  71
  72 Some other useful hints:
  73
  74 - The 'bank' and 'word' numbers can be easily obtained from the mx6 Reference
  75 Manual. For the mx6quad case, please check the "46.5 OCOTP Memory Map/Register
  76 Definition" from the "i.MX 6Dual/6Quad Applications Processor Reference Manual,
  77 Rev. 1, 04/2013" document. For example, for the MAC fuses we have:
  78
  79 Address:
  80 21B_C620        Value of OTP Bank4 Word2 (MAC Address)(OCOTP_MAC0)
  81
  82 21B_C630        Value of OTP Bank4 Word3 (MAC Address)(OCOTP_MAC1)
  83
  84 - The command '=> fuse read 4 2 2' reads the whole MAC addresses at once:
  85
  86 => fuse read 4 2 2
  87 Reading bank 4:
  88
  89 Word 0x00000002: 9f027772 00000004
  90
  91 2. Using imx_usb_loader for first install with SPL
  92 --------------------------------------------------
  93
  94 imx_usb_loader is a very nice tool by BoundaryDevice that
  95 allow to install U-Boot without a JTAG debugger, using
  96 the USB boot mode as described in the manual. It is
  97 a replacement for Freescale's MFGTOOLS.
  98
  99 The sources can be found here:
 100
 101         https://github.com/boundarydevices/imx_usb_loader.git
 102
 103 Booting in USB mode, the i.MX6 announces itself to the Linux Host as:
 104
 105 Bus 001 Device 111: ID 15a2:0061 Freescale Semiconductor, Inc.
 106
 107 imx_usb_loader is able to download a single file (u-boot.imx)
 108 to the board. For boards without SPL support, it is enough to
 109 issue the command:
 110
 111         sudo ../imx_usb_loader/imx_usb -v u-boot.imx
 112
 113 Getting U-Boot when SPL support is active, it requires
 114 two downloads. imx_usb_loader downloads the SPL into
 115 OCRAM and starts it. SPL will check for a valid u-boot.img, and
 116 because it is not found, it will wait for it using the y-modem
 117 protocol via the console.
 118
 119 A first install is then possible by combining imx_usb_loader with
 120 another tool such as kermit.
 121
 122 sudo ../imx_usb_loader/imx_usb -v SPL
 123 kermit kermit_uboot
 124
 125 and kermit_uboot contains something like this (set line should be adjusted):
 126
 127 set line /dev/ttyUSB1
 128 set speed 115200
 129 SET CARRIER-WATCH OFF
 130 set flow-control none
 131 set handshake none
 132 set prefixing all
 133 set file type bin
 134 set protocol ymodem
 135 send u-boot.img
 136 c
 137
 138 The last "c" command tells kermit (from ckermit package in most distros)
 139 to switch from command line mode to communication mode, and when the
 140 script is finished, the U-Boot prompt is shown in the same shell.