[LEDE-DEV] lantiq: cannot access flash on Netgear DM200 while porting LEDE

[Hauke Mehrtens]

On 04/02/2017 05:48 PM, Hauke Mehrtens wrote:
> On 04/02/2017 05:02 PM, Baptiste Jonglez wrote:
>> Hi,
>>
>> I am currently adding LEDE support for the Netgear DM200 VDSL modem
>> [https://wiki.openwrt.org/toh/netgear/dm200], which uses a Lantiq VR9 SoC.
>>
>> I was able to boot LEDE from RAM, and got the LEDs working, but I cannot
>> get the flash to work with LEDE :(
>>
>> The bootloader (u-boot) has access to the flash and says this after
>> initialisation:
>>
>>     8192 KiB W25Q64 at 0:3 is now current device
>>
>> I assumed that it's a NOR flash chip given the size, connected via SPI.
> I found the data sheet here:
> https://www.pjrc.com/store/w25q64fv.pdf
> 
>> The stock firmware only calls it "ltq_sflash" without being more specific.
>> For instance, here is the kernel cmdline from the stock firmware:
>>
>>     root=/dev/mtdblock4 ro rootfstype=squashfs ip=192.168.1.1:192.168.1.10::::eth0:on console=ttyLTQ0,115200 ethaddr=00:E0:92:00:01:40 mem=62M panic=1 mtdparts=ltq_sflash:128k(uboot),64k(gphyfirmware),1600k(kernel),512k(firmware),5120k(rootfs),7232k at 0x30000(image),64k(dniconfig),64k(log),512k(language),64k(sysconfig),8k(ubootconfig),4k(ART),4k(pot),-(ret) init=/etc/preinit vpe1_load_addr=0x83f00000 vpe1_mem=1M ubootver=U-Boot-2010.06-LANTIQ-v-2.3.16.1
>>
>>
>> So, assuming it's similar to other VR9 devices, I used this DTS:
>>
>>        fpi at 10000000 {
>>                 localbus at 0 {
>>                         nor-boot at 0 {
>>                                 compatible = "lantiq,nor";
>>                                 bank-width = <2>;
>>                                 reg = <0 0x0 0x0800000>;
>>                                 #address-cells = <1>;
>>                                 #size-cells = <1>;
>>
>>                                 partitions {
>>                                 // etc
>>
>>
>> But with this DTS, LEDE fails to initialize the flash chip ("probing
>> failed" and nothing in /proc/mtd):
>>
>> [    1.936821] lantiq nor flash device: 00800000 at 10000000
>> [    1.941431] ltq-nor 10000000.nor-boot: probing failed
>> [    2.054037] libphy: lantiq,xrx200-mdio: probed
>> [    2.078013] net-xrx200: invalid MAC, using random
>>
>> I tried setting the CS (Chip Select) in the DTS, because the bootloader
>> uses bus 0 and CS 3 to access the flash.  I added this line to the
>> nor-boot at 0 tree:
>>
>>     lantiq,cs = <3>;
>>
>> but it didn't change anything, LEDE still cannot access the flash.
> 
> It could be that the chip is connected to the SPI controller like on the
> Netgear DGN1000B:
> target/linux/lantiq/dts/DGN1000B.dts
> 
>> How can I find the right parameters for the flash and set them in the DTS?
>> Any guidance would be appreciated!
> 
> Often you can find something in the vendor GPL code, you can get it here:
> http://www.downloads.netgear.com/files/GPL/DM200_GPL_src_V1.0.0.44.tar.gz

The Vendor SDK is based on UGW 6.1.1, based on OpenWrt 12.09 with kernel
3.10 and device tree support. Probably even the vendor image uses a
device tree compiled into the kernel image.
According to the configuration file in
/DM200-V1.0.0.44_gpl_src/config/defconfig_dm200
it would include this dts file:
/DM200-V1.0.0.44_gpl_src/target/linux/lantiq/image/dts/EASY220.dts
In this dts file the flash is connected to the SPI controller.

Hauke

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