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. 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