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eec3f0242   Benoît Thébaudeau   imx: Document fus... 
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  U-Boot for Freescale i.MX6
  
  This file contains information for the port of U-Boot to the Freescale i.MX6
  SoC.
  
  1. CONVENTIONS FOR FUSE ASSIGNMENTS
  -----------------------------------
  
  1.1 MAC Address: It is stored in fuse bank 4, with the 32 lsbs in word 2 and the
      16 msbs in word 3.
6f3bef9e3   Fabio Estevam   doc: README.fuse:... 
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  Example:
  
  For reading the MAC address fuses on a MX6Q:
  
  - The MAC address is stored in two fuse addresses (the fuse addresses are
  described in the Fusemap Descriptions table from the mx6q Reference Manual):
  
  0x620[31:0] - MAC_ADDR[31:0]
  0x630[15:0] - MAC_ADDR[47:32]
  
  In order to use the fuse API, we need to pass the bank and word values, which
  are calculated as below:
  
  Fuse address for the lower MAC address: 0x620
  Base address for the fuses: 0x400
  
  (0x620 - 0x400)/0x10 = 0x22 = 34 decimal
  
  As the fuses are arranged in banks of 8 words:
  
  34 / 8 = 4 and the remainder is 2, so in this case:
  
  bank = 4
  word = 2
  
  And the U-boot command would be:
  
  => fuse read 4 2
  Reading bank 4:
  
  Word 0x00000002: 9f027772
  
  Doing the same for the upper MAC address:
  
  Fuse address for the upper MAC address: 0x630
  Base address for the fuses: 0x400
  
  (0x630 - 0x400)/0x10 = 0x23 = 35 decimal
  
  As the fuses are arranged in banks of 8 words:
  
  35 / 8 = 4 and the remainder is 3, so in this case:
  
  bank = 4
  word = 3
  
  And the U-boot command would be:
  
  => fuse read 4 3
  Reading bank 4:
  
  Word 0x00000003: 00000004
  
  ,which matches the ethaddr value:
  => echo ${ethaddr}
  00:04:9f:02:77:72
  
  Some other useful hints:
  
  - The 'bank' and 'word' numbers can be easily obtained from the mx6 Reference
  Manual. For the mx6quad case, please check the "46.5 OCOTP Memory Map/Register
  Definition" from the "i.MX 6Dual/6Quad Applications Processor Reference Manual,
  Rev. 1, 04/2013" document. For example, for the MAC fuses we have:
  
  Address:
  21B_C620	Value of OTP Bank4 Word2 (MAC Address)(OCOTP_MAC0)
  
  21B_C630	Value of OTP Bank4 Word3 (MAC Address)(OCOTP_MAC1)
  
  - The command '=> fuse read 4 2 2' reads the whole MAC addresses at once:
  
  => fuse read 4 2 2
  Reading bank 4:
  
  Word 0x00000002: 9f027772 00000004