Category: linux

I have spent many hours to work on the RTC part, and I decided to give up for now. I have been able to activate the clock, set the clock, and make it run. But the RTC is not useful. First, it is not battery backed, so when you turn off your device, it will not keep the time. Second, it can store only the seconds, minutes, hours, and day of the month. The problem of not having a documentation is sometimes you get stuck, and don’t know what to try next.

There is one feature that is supposed to be useful if I can make it work: the alarm capability. With alarm, some cron-like applications can set to be notified when a particular time comes (it will ease the CPU burden). As far as I know, the cron daemon doesn’t use this feature, so it is not a great loss.

There is one thing that still puzzles me. The original firmware uses X1205 through an I2C bus. From my understanding, the X1205 have different abilities compared to the STR9100 RTC. So I don’t know whether there is actually another RTC on the board.

Since the RTC is not very useful. I will let go hacking this part until I find other clues.

Here is the output of the original firmware.

X1205: I2C based RTC driver.
i2c-core.o: driver X1205 registered.
X1205: found X1205 on STR9100 I2C Adapter
ccr_write_enable: verify SR failed
i2c-core.o: client [X1205] registered to adapter [STR9100 I2C Adapter](pos. 0).
X1205: i2c_add_driver RTC driver.
X1205: misc_register RTC driver.

I was very tired lately because I have to do many other things beside hacking the agestar kernel. So when I have time this morning, I decided to work on the easiest part on my list: LED driver. Agestar NCB3AST only have one controllable led, inside the casing, so I don’t know how useful this is (I think you can peek a little bit when the casing is closed). The LED and LCD display front is actually controlled by different unit, not controllable by CPU. Because this part is not important, I decided to upload the patch later.

Right now I am starting to look at the RTC driver. Hopefully this one will be more useful.

I have concluded the source of failure for many applications is that the sendfile syscall on my port doesn’t work. To be precise, sendfile sends garbage data to the other side. I have an USB to Ethernet adapter, and using that adapter, the problem disappears. So the conclusion is that my network driver is buggy.

Applications that might be affected are: network servers that sends file (http servers, file servers, etc), distcc.

I will try to fix this tomorrow.

It seems I can get the userland working fine with the latest uClibc snapshot. So far I have been able to boot the kernel using TFTP, and uses root image from NFS and USB, tonight I think I will try to flash the kernel using the mtd driver (for those of you who wants to try before me, flash /dev/mtd1 and use bootpImage for that mtd partition).

Here is the latest patch against 2.6.25.4 (with mtd driver):
patch-2.6.25.4-for-agestar-20080618.bz2

Config file for booting with USB root file system. I am using external USB stick (/dev/sdb1) change it to /dev/sdaX to use the hard disk inside Agestar.

Config file for booting NFS root file system. Don’t forget to change the client IP address (mine is 192.168.1.244), server IP address (mine is 192.168.1.150) and the mount path (mine is /opt/boot).

I finally managed to complete the OHCI part of the driver. Right now some of the most important parts of the kernel are ready: Networking and USB. It means that with the new kernel I will be able to make my Agestar function as NAS. But of course, this is not ready to use yet for most of the people.

Next parts that need to be done are:

• MTD access –> so we can update the flash with the new kernel easily
• RTC (Real Time Clock) –> Not so important if the device is always connected to the internet (we can synchronize the time with NTP every few hours)
• Button –> Not so important (so we can assign the USB_EXIT button to do something when it is pressed)

I am not sure if I can do more work this weekend, so I am publishing the current patch that I have with the config file.

the patch for kernel 2.6.25.4:
http://tinyhack.com/patch-2.6.25.4-for-agestar.bz2

The config file:

http://tinyhack.com/config-2.6.25.4

STR9100 has two Host Controller Interface, EHCI and OHCI. Enhanced Host Controller Interface (EHCI) is used for high speed USB, while Open Host Controller Interface (OHCI) is used for full and low speed devices. I think I have completed the EHCI part (it can detect my USB disk and the internal hard disk), but I haven’t tested this extensively. The OHCI part may not seem important if we only use high speed devices, but it is. When I tried plugging in low speed device, the port becomes unusable (even when I unplug the device and insert a new USB 2.0 device).

I will try to complete the OHCI part, and I hope I can post the source code this weekend after cleaning up the debugging part. I also plan to support the MTD device access so we can update the firmware easily. Updating from the old kernel to the new one will be easy with the web interface, but it is important that we can update the new one also (currently I am still booting from tftp server).

There are quite many limitations using old kernel for Agestar, one of them is you can not install the latest Linux distribution. I am eager to make the new Linux kernel to work on the agestar hardware. So since my last post, mainly I am just hacking at the kernel and not at the userspace stuff. As of today, I managed to boot the new kernel, and wrote a serial driver for it (you can see the boot messages at the end of this post). My next target is to port the USB and/or NIC driver.

As you may have read from my earlier posts, there are no documentations available for the STR 9100 hardware, so I based my work on the source code of the earlier kernel (I can’t believe so many things have changed since the 2.4.36). The initial work is quite easy if you are an experienced kernel developer. Because I am not experienced, I need to study quite many things before reaching the current state.

Because I don’t have any documentation about the FA526 CPU, I took the CPU specific code from the Icy Box. They provide the source code for Kernel 2.6. The SoC uses the same Processor, but completely different hardware for the rest (well, something is better than nothing). For the serial port, I realized that the serial port used is "High-speed 16C550-compliant UART serial channel" http://www.starsemi.com/vChn/Prods/str9104.php, so I studied the source code for 8250.c and added a small code to specify the the UART speed, register mapping, and memory location for the UART IO. This creates a much cleaner code than the original serial_str9100.c source code. The serial_str9100.c was 3799 lines of code, mine was about 100 lines of code (70 lines of code in a separate file, and the rest is adding register mapping to 8250.c).

My next plan is to work on the network driver. This should be not so difficult, at least I have higher hope to make this work compared to the USB part. The old network driver have some conditional compilation that indicates it can be compiled in kernel 2.6. I have tried to compile it, and there were many errors and warnings. I will try removing many codes that was not meant for the Agestar configuration (the kernel was from the WAP2000 router, so it contains router specific codes such as to acess hardware NAT).

Continue reading “Porting Linux Kernel 2.6.25.4 To STAR STR9100 (Agestar)”