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