Hi Everyone!

I'm working on adding device tree support for the ath79 platform. I have experimental patches for several things already however my main problem currently is how the DT should be passed to the kernel.

There were a thread [1] about that on the lmo list in 2011 already, but there were no clear statements about the correct method. I'm using a simple approach during my tests to resolve this problem.

The bootloader puts a magic value to the 'a0' register and the address of the FDT blob is stored in the 'a1' register. I have created the attached patch for U-Boot and that that implements this method. It is against the 'testing' branch of the MIPS U-Boot Custodian Tree [2].

I would like to hear others' opinion about it, before I would invest too much time into an unusable solution. :)

Regards, Gabor

1. http://www.linux-mips.org/archives/linux-mips/2011-06/msg00059.html 2. git://git.denx.de/u-boot-mips.git

3. bootlog with the patched U-Boot:

U-Boot> setenv bootargs 'console=ttyATH0,115200 init=/etc/preinit' U-Boot> setenv serverip 192.168.1.254; setenv ipaddr 192.168.1.1 U-Boot> tftp 0xa0800000 tl-wr703n.dtb dup 1 speed 100 Using eth0 device TFTP from server 192.168.1.254; our IP address is 192.168.1.1 Filename 'tl-wr703n.dtb'. Load address: 0xa0800000 Loading: # done Bytes transferred = 1957 (7a5 hex) U-Boot> tftp 0xa0900000 openwrt-ath79-uImage-initramfs-lzma.bin Using eth0 device TFTP from server 192.168.1.254; our IP address is 192.168.1.1 Filename 'openwrt-ath79-uImage-initramfs-lzma.bin'. Load address: 0xa0900000 Loading: ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ################################################################# ########################################################### done Bytes transferred = 2627551 (2817df hex) U-Boot> bootm 0xa0900000 - 0xa0800000 ## Booting kernel from Legacy Image at a0900000 ... Image Name: MIPS OpenWrt Linux-3.8-rc2 Created: 2013-01-07 19:54:05 UTC Image Type: MIPS Linux Kernel Image (lzma compressed) Data Size: 2627487 Bytes = 2.5 MiB Load Address: 80060000 Entry Point: 80060000 Verifying Checksum ... OK ## Flattened Device Tree blob at a0800000 Booting using the fdt blob at 0xa0800000 Uncompressing Kernel Image ... OK Loading Device Tree to 81f72000, end 81f757a4 ... OK

Starting kernel ...

Linux version 3.8.0-rc2 (juhosg@mag2) (gcc version 4.6.4 20121106 (prerelease) (Linaro GCC 4.6-2012.11) ) #456 Mon Jan 7 20:53:57 CET 2013 ath79: using Device Tree passed by bootloader bootconsole [early0] enabled CPU revision is: 00019374 (MIPS 24Kc) SoC: Atheros AR9330 rev 1 Clocks: CPU:400.000MHz, DDR:400.000MHz, AHB:200.000MHz, Ref:25.000MHz Determined physical RAM map: memory: 02000000 @ 80000000 (usable) memory: 02000000 @ 00000000 (usable) Initrd not found or empty - disabling initrd Zone ranges: Normal [mem 0x00000000-0x1fffffff] Movable zone start for each node Early memory node ranges node 0: [mem 0x00000000-0x01ffffff] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes. Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32 bytes Built 1 zonelists in Zone order, mobility grouping on. Total pages: 8128 Kernel command line: console=ttyATH0,115200 init=/etc/preinit rootfstype=squashfs,yaffs,jffs2 noinitrd PID hash table entries: 128 (order: -3, 512 bytes) Dentry cache hash table entries: 4096 (order: 2, 16384 bytes) Inode-cache hash table entries: 2048 (order: 1, 8192 bytes) __ex_table already sorted, skipping sort Writing ErrCtl register=00000000 Readback ErrCtl register=00000000 Memory: 26784k/32768k available (2682k kernel code, 5984k reserved, 822k data, 1548k init, 0k highmem) SLUB: Genslabs=9, HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 NR_IRQS:51 Calibrating delay loop... 265.42 BogoMIPS (lpj=1327104) pid_max: default: 32768 minimum: 301 Mount-cache hash table entries: 512 NET: Registered protocol family 16 ATH79: using Flattened Device Tree bio: create slab <bio-0> at 0 cfg80211: Calling CRDA to update world regulatory domain Switching to clocksource MIPS NET: Registered protocol family 2 TCP established hash table entries: 512 (order: 0, 4096 bytes) TCP bind hash table entries: 512 (order: -1, 2048 bytes) TCP: Hash tables configured (established 512 bind 512) TCP: reno registered UDP hash table entries: 256 (order: 0, 4096 bytes) UDP-Lite hash table entries: 256 (order: 0, 4096 bytes) NET: Registered protocol family 1 squashfs: version 4.0 (2009/01/31) Phillip Lougher jffs2: version 2.2. (NAND) (SUMMARY) © 2001-2006 Red Hat, Inc. msgmni has been set to 52 io scheduler noop registered io scheduler deadline registered (default) Serial: 8250/16550 driver, 1 ports, IRQ sharing disabled 18020000.uart: ttyATH0 at MMIO 0x18020000 (irq = 11) is a AR933X UART console [ttyATH0] enabled, bootconsole disabled console [ttyATH0] enabled, bootconsole disabled ieee80211 phy0: Atheros AR9330 Rev:0 mem=0xb8100000, irq=2 TCP: cubic registered NET: Registered protocol family 17 8021q: 802.1Q VLAN Support v1.8 Freeing unused kernel memory: 1548k freed input: buttons.3 as /devices/buttons.3/input/input0

• preinit -

Press the [f] key and hit [enter] to enter failsafe mode

• regular preinit -
• init -

SCSI subsystem initialized usbcore: registered new interface driver usbfs usbcore: registered new interface driver hub usbcore: registered new device driver usb PPP generic driver version 2.4.2 ip_tables: (C) 2000-2006 Netfilter Core Team NET: Registered protocol family 24 ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver nf_conntrack version 0.5.0 (442 buckets, 1768 max) ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver Initializing USB Mass Storage driver... usbcore: registered new interface driver usb-storage USB Mass Storage support registered. usbcore: registered new interface driver ums-alauda usbcore: registered new interface driver ums-cypress usbcore: registered new interface driver ums-datafab usbcore: registered new interface driver ums-freecom usbcore: registered new interface driver ums-isd200 usbcore: registered new interface driver ums-jumpshot usbcore: registered new interface driver ums-karma usbcore: registered new interface driver ums-sddr09 usbcore: registered new interface driver ums-sddr55 usbcore: registered new interface driver ums-usbat

Please press Enter to activate this console.

BusyBox v1.19.4 (2013-01-06 20:43:13 CET) built-in shell (ash) Enter 'help' for a list of built-in commands.

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| |.-----.-----.-----.| | | |.----.| |_ | - || _ | -__| || | | || _|| _| |_______|| __|_____|__|__||________||__| |____| |__| W I R E L E S S F R E E D O M

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BARRIER BREAKER (Bleeding Edge, r35026)

• 1/2 oz Galliano Pour all ingredients into
• 4 oz cold Coffee an irish coffee mug filled
• 1 1/2 oz Dark Rum with crushed ice. Stir.
• 2 tsp. Creme de Cacao

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root@OpenWrt:/#