System Setup

The setup used includes:

• Zcomax XG-180MU SDIO Wifi module
• Compulab cm-x270 + sb-x270 system (includes the PXA270 processor)
• Linux kernel 2.6.24-rc5
• OpenEmbedded

Support for the Marvell 8385 and 8686 based Wifi chipsets is now included in the mainstream Linux kernel 2.6.24 release candidate source code.  To use this driver, enable the CONFIG_LIBERTAS_SDIO option.  I also had to enable the CONFIG_WIRELESS_EXT option to prevent a compile error, but this is probably required anyway to build a functioning wireless system.

Firmware

The firmware for the Marvell SDIO wifi solutions is downloaded at runtime, so the next challenge is to find firmware files.  I am working on a project that has access to a driver from Marvell, so I was able to extract this firmware from their source code header files.  I'm sure there are other places where this firmware is available.   The firmware files must be placed in the following location:

root@cm-x270:~$ ls /lib/firmware/sd*
/lib/firmware/sd8385.bin         /lib/firmware/sd8385_helper.bin

The version of udev used in OpenEmbedded determines the location of the firmware files.  The Libertas Linux driver requests these firmware files, and a userspace component of udev provides these files to the kernel.

Success

The following kernel modules are required:

root@cm-x270:~$ lsmod
Module                  Size  Used by
pxamci                  7008  0
libertas_sdio           8488  0
mmc_core               46868  2 pxamci,libertas_sdio
libertas               85288  1 libertas_sdio
ieee80211              29956  1 libertas
ieee80211_crypt         4768  1 ieee80211
root@cm-x270:~$

And the result:

root@cm-x270:~$ modprobe pxamci
root@cm-x270:~$ mmc0: new SDIO card at address 0001
libertas: eth1: Marvell WLAN 802.11 adapter

ifconfig -a

... 

eth1      Link encap:Ethernet  HWaddr 00:60:B3:34:77:66
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

Very nice!

So it looks like there is finally an embedded Wifi solution for products that sell less than 500,000 units per year.  I also briefly tried this on a AT91SAM9260 system, but it did not work.  So there is still some work to do on the Linux SDHC driver for the AT91SAM9260.