README
1Board information
2-----------------
3
4The SBC produced by Phytec has a SOM based on a i.MX6Q.
5The SOM is sold in two versions, with eMMC or with NAND. Support
6here is for the SOM with NAND.
7The evaluation board "phyBoard-Mira" is thought to be used
8together with the SOM.
9
10More information on the board can be found on manufacturer's
11website:
12
13http://www.phytec.de/produkt/single-board-computer/phyboard-mira/
14http://www.phytec.de/fileadmin/user_upload/images/content/1.Products/SOMs/phyCORE-i.MX6/L-808e_1.pdf
15
16Building U-Boot
17-------------------------------
18
19$ make pcm058_defconfig
20$ make
21
22This generates the artifacts SPL and u-boot.img.
23The SOM can boot from NAND or from SD-Card, having the SPI-NOR
24as second option.
25The dip switch "DIP-1" on the board let choose between
26NAND and SD.
27
28DIP-1 set to off: Boot first from NAND, then try SPI
29DIP-1 set to on: Boot first from SD, then try SPI
30
31The bootloader was tested with DIP-1 set to on. If a SD-card
32is present, then the RBL tries to load SPL from the SD Card, if not,
33RBL loads from SPI-NOR. The SPL tries then to load from the same
34device where SPL was loaded (SD or SPI). Booting from NAND is
35not supported.
36
37Flashing U-Boot onto an SD card
38-------------------------------
39
40After a successful build, the generated SPL and U-Boot binaries can be copied
41to an SD card. Adjust the SD card device as necessary:
42
43$ sudo dd if=u-boot-with-spl.imx of=/dev/mmcblk0 bs=1k seek=1
44
45This is equivalent to separately copying the SPL and U-Boot using:
46
47$ sudo dd if=SPL of=/dev/mmcblk0 bs=1k seek=1
48$ sudo dd if=u-boot-dtb.img of=/dev/mmcblk0 bs=1k seek=197
49
50The default bootscripts expect a kernel fit-image file named "fitImage" in the
51first partition and Linux ext4 rootfs in the second partition.
52
53Flashing U-Boot to the SPI Flash, for booting Linux from NAND
54-------------------------------------------------------------
55
56The SD card created above can also be used to install the SPL and U-Boot into
57the SPI flash. Boot U-Boot from the SD card as above, and stop at the autoboot.
58
59Then, clear the SPI flash:
60
61=> sf probe
62=> sf erase 0x0 0x1000000
63
64Load the equivalent of u-boot-with-spl.imx from the raw MMC into memory and
65copy to the SPI. The SPL is expected at an offset of 0x400, and its size is
66maximum 392*512-byte blocks in size, therefore 0x188 blocks, totaling 0x31000
67bytes. Assume U-Boot should fit into 640KiB, therefore 0x500 512-byte blocks,
68totalling 0xA0000 bytes. Adding these together:
69
70=> mmc read ${loadaddr} 0x2 0x688
71=> sf write ${loadaddr} 0x400 0xD1000
72
73The SPL is located at offset 0x400, and U-Boot at 0x31400 in SPI flash, as to
74match the SD Card layout. This would allow, instead of reading from the SD Card
75above, with networking and TFTP correctly configured, the equivalent of:
76
77=> tftp u-boot-with-spl.imx
78=> sf write ${fileaddr} 0x400 ${filesize}
79
80The default NAND bootscripts expect a single MTD partition named "rootfs",
81which in turn contains the UBI volumes "fit" (which contains the kernel fit-
82image) and "root" (which contains a ubifs root filesystem).
83
84The "bootm_size" variable in the environment
85--------------------------------------------
86
87By default, U-Boot relocates the device tree towards the upper end of the RAM,
88which kernels using CONFIG_HIGHMEM=y may not be able to access during early
89boot. With the bootm_size variable set to 0x30000000, U-Boot relocates the
90device tree to below this address instead.
91