xref: /openbmc/u-boot/doc/README.nokia_rx51 (revision 66dae3bb)
1Board: Nokia RX-51 aka N900
2
3This board definition results in a u-boot.bin which can be chainloaded
4from NOLO in qemu or on a real N900. It does very little hardware config
5because NOLO has already configured the board. Only needed is enabling
6internal eMMC memory via twl4030 regulator which is not enabled by NOLO.
7
8NOLO is expecting a kernel image and will treat any image it finds in
9onenand as such. This u-boot is intended to be flashed to the N900 like
10a kernel. In order to transparently boot the original kernel, it will be
11appended to u-boot.bin at 0x40000. NOLO will load the entire image into
12(random) memory and execute u-boot, which saves hw revision, boot reason
13and boot mode ATAGs set by NOLO. Then the bootscripts will attempt to load
14uImage or boot.scr from a fat, ext2/ext3 or ext4 filesystem in external
15SD card or internal eMMC memory. If this fails or keyboard is closed then
16the appended kernel image will be booted using some generated and some
17stored ATAGs (see boot order).
18
19There is support for hardware watchdog. Hardware watchdog is started by
20NOLO so u-boot must kick watchdog to prevent reboot device (but not very
21often, max every 2 seconds). There is also support for framebuffer display
22output with ANSI espace codes and the N900 HW keyboard input. USB tty works
23but is disabled because it prevents the current Maemo kernel from booting.
24
25When U-Boot is starting it enable IBE bit in Auxiliary Control Register,
26which is needed for Thumb-2 ISA support. It is workaround for errata 430973.
27
28Default boot order:
29
30 * 0. if keyboard is closed boot automatically attached kernel image
31 * 1. try boot from external SD card
32 * 2. try boot from internal eMMC memory
33 * 3. try boot from attached kernel image
34
35Boot from SD or eMMC in this order:
36
37 * 1.
38   * 1.1 find boot.scr on first fat partition
39   * 1.2 find uImage on first fat parition
40   * 1.3 same order for 2. - 4. fat partition
41 * 2. same as 1. but for ext2/3 partition
42 * 3. same as 1. but for ext4 partition
43
44
45Available additional commands/variables:
46
47 * run sercon - Use serial port for control
48 * run usbcon - Use usbtty for control
49 * run vgacon - Use framebuffer and HW keyboard for control (default)
50
51 * run sdboot - Boot from external SD card (see boot order)
52 * run emmcboot - Boot from internal eMMC memory (see boot order)
53 * run attachboot - Boot attached kernel image (attached to U-Boot binary)
54
55 * run scriptload - Load boot script ${mmcscriptfile}
56 * run scriptboot - Run loaded boot script
57 * run kernload - Load kernel image ${mmckernfile}
58 * run initrdload - Load initrd image ${mmcinitrdfile}
59 * run kernboot - Boot loaded kernel image
60 * run kerninitrdboot - Boot loaded kernel image with loaded initrd image
61
62 * run trymmcscriptboot - Try to load and boot script ${mmcscriptfile}
63 * run trymmckernboot - Try to load and boot kernel image ${mmckernfile}
64 * run trymmckerninitrdboot - Try to load and boot kernel image ${mmckernfile}
65			      with initrd image ${mmcinitrdfile}
66
67Additional variables for loading files from mmc:
68
69 * mmc ${mmcnum} (0 - external, 1 - internal)
70 * partition number ${mmcpart} (1 - 4)
71 * parition type ${mmctype} (fat, ext2)
72
73Additional varuables for booting kernel:
74
75 * setup_omap_atag - Add OMAP table into atags structure (needs maemo kernel)
76 * setup_console_atag - Enable serial console in OMAP table
77 * setup_boot_reason_atag - Change boot reason in OMAP table
78 * setup_boot_mode_atag - Change boot mode in OMAP table
79
80USB TTY:
81
82 Maemo kernel 2.6.28 will crash if u-boot enable usb tty. So USB TTY is disabled.
83 For enabling USB TTY just add this line to file include/configs/nokia_rx51.h
84
85 #define CONFIG_USB_TTY
86
87
88ONENAND support:
89
90 ONENAND support is disabled because not working yet and cause linux kernel to
91 crash or no access to mtd. For enabling ONENAND support add this line at begin
92 of file include/configs/nokia_rx51.h
93
94 #define ONENAND_SUPPORT
95
96
97UBIFS support:
98
99 UBIFS support is disabled, because U-Boot image is too big and cannot be
100 flashed with attached zImage to RX-51 kernel nand area. For enabling UBIFS
101 support first enable ONENAND support and then add this line at begin of file
102 include/configs/nokia_rx51.h
103
104 #define UBIFS_SUPPORT
105