[u-boot.git] / doc / README.imx6

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
Commit	Line	Data
eec3f024 BT	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.
6f3bef9e FE	11
	12	Example:
	13
	14	For reading the MAC address fuses on a MX6Q:
	15
	16	- The MAC address is stored in two fuse addresses (the fuse addresses are
	17	described in the Fusemap Descriptions table from the mx6q Reference Manual):
	18
	19	0x620[31:0] - MAC_ADDR[31:0]
	20	0x630[15:0] - MAC_ADDR[47:32]
	21
	22	In order to use the fuse API, we need to pass the bank and word values, which
	23	are calculated as below:
	24
	25	Fuse address for the lower MAC address: 0x620
	26	Base address for the fuses: 0x400
	27
	28	(0x620 - 0x400)/0x10 = 0x22 = 34 decimal
	29
	30	As the fuses are arranged in banks of 8 words:
	31
	32	34 / 8 = 4 and the remainder is 2, so in this case:
	33
	34	bank = 4
	35	word = 2
	36
	37	And the U-boot command would be:
	38
	39	=> fuse read 4 2
	40	Reading bank 4:
	41
	42	Word 0x00000002: 9f027772
	43
	44	Doing the same for the upper MAC address:
	45
	46	Fuse address for the upper MAC address: 0x630
	47	Base address for the fuses: 0x400
	48
	49	(0x630 - 0x400)/0x10 = 0x23 = 35 decimal
	50
	51	As the fuses are arranged in banks of 8 words:
	52
	53	35 / 8 = 4 and the remainder is 3, so in this case:
	54
	55	bank = 4
	56	word = 3
	57
	58	And the U-boot command would be:
	59
	60	=> fuse read 4 3
	61	Reading bank 4:
	62
	63	Word 0x00000003: 00000004
	64
	65	,which matches the ethaddr value:
	66	=> echo ${ethaddr}
	67	00:04:9f:02:77:72
	68
	69	Some other useful hints:
	70
	71	- The 'bank' and 'word' numbers can be easily obtained from the mx6 Reference
	72	Manual. For the mx6quad case, please check the "46.5 OCOTP Memory Map/Register
	73	Definition" from the "i.MX 6Dual/6Quad Applications Processor Reference Manual,
	74	Rev. 1, 04/2013" document. For example, for the MAC fuses we have:
75
76	Address:
77	21B_C620 Value of OTP Bank4 Word2 (MAC Address)(OCOTP_MAC0)
78
79	21B_C630 Value of OTP Bank4 Word3 (MAC Address)(OCOTP_MAC1)
80
81	- The command '=> fuse read 4 2 2' reads the whole MAC addresses at once:
82
83	=> fuse read 4 2 2
84	Reading bank 4:
85
86	Word 0x00000002: 9f027772 00000004