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