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