coreboot changelog – Week of 2015-07-20

This covers commits 406effd5 up to commit ef0158ec

Apart from adding the google/glados board, this week’s activity concentrated on bug fixes in chipsets and mainboards, spanning AMD K8 and Hudson, Intel Sandy Bridge, Braswell and Skylake, Nvidia Tegra, Rockchip RK3288 and RISC-V. Most of the changes are too small individually and too spread out across the code base for a shout-out (or this report becomes just a fancy kind of “git log”), but two changes stand out:

Native RAM init on Sandybridge gained support for multiple DIMMs on the same channel, further improving the reverse engineered code base for that chipset.

To improve Skylake support, our 8250mem serial port driver now also supports Skylake’s 32bit UART access mode. This may also be useful when reducing code duplication in our serial console drivers (such as on ARM SoCs).

[GSoC] EC/H8S firmware week #7|#8

Week #7 was is little bit frustrating, because of no real progress, only more unfinished things which aren’t working. Week #8 was a lot better.

1. Sniffing the communication between the 2 embedded controllers H8S and PMH4.

I’ve tried to build an protocol analyser with the msp430, but the data output was somehow strange. For testing purpose I used my H8S firmware to produce testing data. But the msp430 decoded only wrong data. I’m using IRQs on the clock to do the magic and writing it to a buffer before transmitting it via UART. Maybe the msp430 is too slow for that? Possible. Set a GPIO to high when the IRQ routing start and to low when it ends. Visualize the clock signal and connect the  IRQ measure pin to an oscilloscope. The msp430 is far too slow. I’m using memory dereference in the IRQ routine, which takes a lot of time. Maybe the msp430 is fast enough, when using asm routine and registers to buffer the 3 byte transmission. But a logic analyser would definitely work. So I borrowed two logic analyser. An OLS (Openbench Logic Sniffer) and a Saleae Logic16.

There isn’t so much data on the lines. Every 50 ms there is a short transmission of 3 byte. But I don’t want to decode the data by hand. So it needs a decoder for the logic analyser. sigrok looks like the best start point and both analyser are supported.

I’ve started with the Openbench Logic Sniffer, but unfortunately it doesn’t have enough RAM to buffer the input long enough. Maybe the external trigger input can be used. But before doing additional things I would like to test with the Logic16.

The Logic16 doesn’t support any triggers but it can stream all data over USB even with multiple MHz. Good enough to capture all data. I found out that the best samplerate is 2 MHz. Otherwise the LE signal isn’t captured, because it’s a lot shorter than a clock change. In the end I created a decoder with libsigrokdecode.

sigrok-cli -i –channels 0-3 -P ec_xp:clk=2:data=3:le=1:oe=0 | uniq -c 

67 0x01 0x07 0xc8
3 0x01 0x04 0xc8 
4 0x01 0x10 0x48
1120 0x01 0x17 0x48
67 0x01 0x07 0xc8

0x01 0x07 0xc8 is called when only power is plugged in, like a watchdog(every 500ms)
0x01 0x17 0x48 is called when the device is powered on, like a watchdog (every 50ms)
0x01 0x04 0xc8 around the time power button pressed
0x01 0x10 0x48 around the time power button pressed

2. Flash back the OEM H8S firmare

The OEM H8S firmware is included in the bios updates. cabextract and strings is enough for extracting it out of the update. Look for SREC lines. Put the SREC lines into a separate file and flash them back via UART bootloader and the renesas flash tool. The display powers up and it’s booting again with OEM BIOS.
I could imagine they are using a similar update method like the UART bootloader. First transfer a flasher application into RAM and afterwards communicate with the flasher to transfer the new firmware, but the communication works over LPC instead of UART.

3. Progress on the bootloader

I’ve implemented the ADC converter to enable the speaker amp and the display backlight brightness.

Written down LPC registers and just enable the Interface in order to get GateA20 working. Still unclear how far this works.

4. How to break into the bootloader?

The idea of the bootloader is providing a brick free environment for further development. The bootloader loads the application which adds full support for everything. It should be possible to stop the loading application and flash a new application into the EC flash. When starting development on the x60 or x201 I want to use I2C line as debug interface. I2C chips have a big footstep and are easy to access. But there must be a way to abort the loading. I will use the function key in combination with the leds.

  1. Remove the battery and power plug.
  2. Press the function key
  3. Put the power plug in
  4. Wait until leds blinking
  5. release the function key within 5 seconds after the leds starting to blink to enter the bootloader.

The H8S will become I2C slave on a specific address.

What next?

  • Add new PMH4 commands to the H8S
  • solder additional pins to MAINOFF PWRSW_H8 A20 KBRC
  • use the logic analyser to put the communication in relation with these signals
  • UART shell
  • I2C master & client
  • solder LPC pins to analyse firmware update process
  • test T40 board with new PMH4 commands and look if all power rails are on

coreboot changelog – Week of 2015-07-13

This covers commits 6cb3a59 (which is the 4.1 tag) up to commit 406effd5

This week brought the addition of one new chipset and four new mainboards: Welcome the Intel Skylake SoC, and the new mainboards google/cyan, intel/kunimitsu, intel/sklrvp, and intel/strago, which are Braswell or Skylake based.

As for tools, the script that generated the 4.1 release was added to the tree. To aid with debugging build issues, buildgcc shows the URLs it uses to download the sources to the toolchain. The standard git hook now uses a customized version of Linux’s utility for better coding style compliance tests. The cbmem utility gained OpenBSD compatibility when reading timestamps.

The USB host drivers in libpayload saw improvements both for USB3, supporting SuperSpeed hubs and showing more robustness in the presence of strangely behaving USB devices, and for DWC2 controllers, which now support LowSpeed devices behind HighSpeed hubs. coreboot also passes more information to libpayload on where to find the flash part as well as the parameters of the CBFS that was used during boot.

The CBFS format is seeing new development: The default alignment for files is now hardcoded to 64 bytes, which was already the default. There are no known instances where this value was changed, and it simplifies development going forward. The change is forward compatible in that old users can still read new CBFS images. New users run into problems if they work on a CBFS image with a different alignment configuration.

Furthermore there were discussions on how to extend the CBFS format compatibly. So far this led to numerous refactorings in cbfstool to simplify further development.

Finally, there were a whole lot of bug fixes: ARM64, the code for Nvidia’s Tegra210 chipset and the google/foster and google/smaug boards saw lots of development, from making them boot again to various hardware enablement. AMD’s RS780 chipset was effectively disabled due to a typo in the build system. There’s an ongoing effort to bring AMD K8/Fam10h into shape again, which also positively affected HD Audio configuration. CBMEM timestamps are more complete than ever.

There was also the usual bunch of cleanups that get rid of unused Kconfig symbols and configuration options, deal with wrong indentation, and replace magic numbers with meaningful names.

[GSoC] End user flash tool – week #6

Hello again! During week 6 I worked on two things:

  • functional tests of libflashrom on T60
  • GUI improvements – filtering and searching list of supported hardware

For testing I used Lenovo T60 with Macronix chip and Raspberry Pi. I connected to the chip with SOIC clip and attached it to Raspberry SPI. I needed to disassemble my laptop almost completely because on T60 BIOS chip is blocked by a magnesium frame which must be removed. It is important for me to have easier access to the chip without disassembling everything every time so  I removed a part of frame that covered the chip.


Tested functions:

  • fl_flash_probe: function returns proper flash context if we provide a specific chip as its argument, if we probe for all known chips and there are multiple chips found (like in Lenovo T60 with Macronix chip) correct error code is returned (I also needed to implement a way to output multiple flash chips to GUI and then select a proper one, I will describe it in my next post).
  • fl_image_read: correct data is loaded to buffer
  • fl_flash_erase:  chip has been properly erased
  • fl_image_verify: verification succeeded
  • fl_image_write: data has been correctly written on the chip
filtering and searching supported hardware

It is possible now to find a specific chip, board or chipset on the list by selecting filtering options like vendor, size or test status. You can also search by entering a name of a particular hardware (or part of a name). I plan to extend this screen and provide more filtering options when I will finish implementing higher priority features like automating a process of creating a working coreboot image and checking hardware compatibility.


Announcing coreboot 4.1

Dear coreboot community,

It has been more than 5 years since we have “released” coreboot ‘4.0’.
That last release marked some very important milestones that we originally prototyped in the abandoned LinuxBIOS v3 efforts, like the coreboot filesystem (CBFS), Kconfig support, and (strictly) separate device trees, build logic and configuration.

Since then there have been as many significant original developments, such as support for many new architectures (ARM, ARM64, MIPS, RISC-V), and related architectural changes like access to non-memory mapped SPI flash, or better insight about the internals of coreboot at runtime through the cbmem console, timestamp collection, or code coverage support.

It became clear that a new release is overdue. With our new release process only slowly getting in shape, I decided to take a random commit and call it ‘4.1’.

The release itself happens at an arbitrary point in time, but will serve as a starting point for other activities that require some kind of ‘starting point’ to build on, described below.

Future releases will happen more frequently, and with more guarantees about the state of the release, like having a cool down phase where boards can be tested and so on. I plan to create a release every three months, so the changes between any two release don’t become too

With the release of coreboot 4.1, you get an announcement (this email), a git tag (4.1), and tar archives at, for the coreboot sources and the redistributable blobs.

Starting with coreboot 4.1, we will maintain a high level changelog and ‘flag days’ document. The latter will provide a concise list of changes which went into coreboot that require chipset or mainboard code to change to keep it working with the latest upstream coreboot.

For the time being, I will run these efforts, but I’ll happily share documentation duties with somebody else – it is a great opportunity to keep track of things, learn about the project and its design and various internals, while contributing to the project without the need to code.

Please contact me (for example by email or on IRC) if you’re interested, and we’ll work out how to collaborate on this.

The process should enable users of coreboot to follow releases if they want a more static base to build on, while making it easier to follow along with new developments by providing upgrade documentation.

Since moving away from a rolling (non-)release model is new for coreboot, things may still be a bit rough around the edges, but I’ll provide support for any issues that arise from the release process.


[GSoC] EC/H8S firmware week #6

This week I looked at the communication between the EC H8S and the PMH4. The PMH4 (likely power management hub) is an ASIC which takes care of the power control. It controls who get’s power and who not. It doesn’t do any high level work, more like a big logic gatter. The PMH4 has inputs from several power good pins from different power rails and chips. On the output side it controls some power rails. It can also reset the H8S. The PMH4 also knows over some pins in which power state (ACPI S0,S4,S5) the board is. It doesn’t do any high level work. It’s more like a big logic gatter. There are no ADC on any power lines.

The PMH4 is connected to the H8S via 4 Pins. ~OE LE DATA CLK.

gsoc 2015 pmh4 connector t40

I connected a buspirate in SPI sniffer mode to debug the protocol. But the output looked a little bit strange. There was no data from the PMH4 to H8S (MISO) and the data comes in burst. To get more knowledge on the protocol I used a digital oscilloscope.

pmh4 oscilloscope

The protocol doesn’t look like SPI. LE get’s low after every transmission, ~OE is just high, clock and data just transfer the data. Sometimes when the H8S gets an interupt the Clock pause for some time and continues with the data afterwards. The clock is around ~400kHz.

I confirmed the protocol via the oscilloscope, but still I don’t get any sign from the board. No fan, nothing else. There must be more than this single transmisison. Maybe the board is to much damaged. My modified board was already broken when I got it. There is a loose connection related to the cardbus. Maybe this is my problem I don’t know.

I’ve two board with two connectors for the PMH4 here. Why not using the OEM one as starter help for the other one?

t42 gives some starting help

I think the PMH4 does what it should do. The H8S has an digital-analog-converter pin connected to the video brightness. But I haven’t implemented it yet. But I don’t think the device booted, because neither the CPU nor the chipset produce any heat. Ok, maybe it does, I only used my finger as thermometer. A thermal camera would help here. I’ll borrow a thermal camera for that.

There are lot of pins which I ignore atm. E.g. A20 pin. Is there something to do in a specific time serie?

What’s next?

  • build a small protocol sniffer for the PMH4 XP using a msp430 or stellaris arm
  • make progress on the bootloader
  • find a way to flash back the OEM H8S firmware
  • find a way to flash my bootloader via OEM flash tools

My requirements to the bootloader are

  • UART flashing via XMODEM
  • a simple UART shell
  • I2C as recovery and shell as well

I2C pins are a lot easier to find and modify than the H8S UART. I’m not yet sure if the H8S should be the master or the slave and on what address he should use? Multiple? UART tx is working. Rx is a task to do.

PMH4 / PMH7 / Thinker communication

On newer board the PMH interfaces changed (>= x60, t60, …). They merge the LPC interface and the XP interface into an protocol over SPI. And the new PMH is used as GPIO expander as well.

pmh4 pmh7 thinker communication


[GSoC] EC/H8S firmware week #5

The T40 is flashing leds! The toolchain is still a little bit tricky. I’m using the debian package gcc-h8300-hms, written a small linker script and took the startup assembly routine from Johann Gysin’s led radiator.

Now I can flash leds. But what about booting the board? I would say it’s enough to put

  • (!MAINOFF) = high
  • FAN ON = high
  • pulse high on (!PWRSW_H8)

But it’s not enough. Also the FAN isn’t starting to rotate. I’ll try to debug every pin this week and solder some debug pins for the 2nd EC (PMHx) to the my modified T40 as well as to an unmodified T42p. The H8S is talking to the PMHx via SPI, while the H8S is the master and is doing bit banging SPI in software, because it doesn’t have a hardware unit for that. I’ll also use these pins for testing my SPI implementation. I’ll try to reuse an open source SPI implementation.

I also asked me if it’s a good idea to port coreboot for the T40 before continuing any efforts to the EC, but it’s a little bit harder, because the T40 uses a LPC/FWH flash in a TSOP40 case. Another option is changing the hardware to a board which is already supported by coreboot like a x60/t60 or x201. But it’s much more harder to access the 8 pins for flashing the EC on these boards.

Before switching to another board, the powersequencing must work and I need a robust recovery way, because when you kill the EC by flashing a new firmware, you don’t get a second chance, unless you solder a lot. Chrome EC fix this problem by splitting the EC firmware into 2 parts. One read-only part and one read-write’able part. Only the second part gets updated and the read-only part can at least boots the device.

Before starting the H8S port for Chrome EC I want to have a bootloader. Because it would improve developing speed. I think implement this is much faster than doing the full Chrome EC support and most of the bootloader code can be re-used for Chrome EC.

I’m also not perfectly sure Chrome EC is the best solution. It’s special use-case is EC, which is perfect. But neither the documentation (I think there is more than one page) nor the bugtracker is public. Thus it makes difficult to use. I’m also not sure if Chrome EC would apply my H8S port into their repository.

[GSoC] End user flash tool – week #4 #5

Hello! During week #4 and #5 I worked on several cases:

  1. Integration of cbfs_tool features.
  2. Improving libflashrom querying functions / integrating already existing patches.
  3. Extending and improving GUI.
Integration of cbfs_tool features

cbfs_tool is bigger project than bios_extract, so I took a little more to integrate it than during bios_extract integration as I needed to do some investigation how it works. I imported code related to:

  • creating rom file
  • adding components like stage, payload, option rom, bootsplash etc.
  • printing rom content
  • deleting components.

The same like in case of libflashrom and bios_extract I created a static library and linked it with flash tool.

IMPROVING LIBFLASHROM querying functions / integrating patches

After posting my draft patch for initial review on flashrom mailing list I got great feedback which helped me a lot. Urja Rannikko and Stefan Tauner pointed my mistakes and proposed improvements, moreover Anton Kochkov shared his libflashrom changes where he worked on similiar issues.  This community is really helpful. Thanks!

So, I did improvements in querying functions. Currently we have:

const char** fl_supported_programmers(void);
const char* fl_version(void);
fl_flashchip_info *fl_supported_flash_chips(void);
fl_board_info *fl_supported_boards(void);
fl_chipset_info *fl_supported_chipsets(void);
int fl_supported_info_free(void *p);

Unnecessary functions which return number of supported hardware of certain type have been removed. Now we can call functions to allocate the table and get a pointer to it. Of course I will create a patch and post it for second review.

I had a problem as my SOIC clip did not arrive on time, I was not able to test operations related functions on my T60. Actually it was my fault because I have not noticed a comment on internet auction that it may go from China. I have been waiting for 3 weeks for its arrival. Now I already have it so my main focus this week is to test libflashrom on real hardware.

extending / improving gui

I extended a GUI part to allow user to manipulate with rom contents like adding payload, bootsplash etc. and also removing such components. Of course this is not a main purpose of my project. The main focus is to create a tool which will allow user to don’t care about which options are correct. I will be going in this direction, I want to automate a process of creating a coreboot image as much as possible. So currently this is a kind of ‘advanced mode’. I implemented it for several reasons:

  • after integration of bios_extract, cbfs_tool and libflashrom it was not big effort to do it
  • implementing and testing it helped me to better understand integrated code and its features
  • there are also advanced users who may want to do some manual changes

Tasks for current week:

  • test probing, reading, flashing with libflashrom on T60 (through linux_spi)
  • GUI improvements proposed by Stefan Tauner(searching, sorting and filtering in supported hardware screen)
  • code cleanup

[GSoC] EC/H8S firmware week #3|4

In the last 2 weeks I managed to flash the H8S on the T40 using the OEM Renesas Flash Tool including their flash application. Flashing works in 2 steps, first upload a flash application into the H8S. Second this flash application will receive the firmware (via serial) and write it into the flash. Thanks to Renesas this application is available in source code. I would like to write an own flasher later.

But I wasn’t able to create a proper application yet. I could write the led programm in assembly, but having a working c compile is needed anyway.

I built a toolchain with gcc 4.9.2. The toolchain buildscript is very simple and can be found on github. I stopped my building efforts for now (building one based on gcc 4.4.6). There’s also a debian package for h8300 (based on gcc 3.4.6) which may be a good alternative. Before continuing in building toolchains and my led application, I’m reading me into linkerscipts and take a look how the compiler is working (e.g. what must a crt0 do?).

At the moment I know how the application should be compiled, where the reset vectors are and where the entrypoint. But putting these things together into a binary image is my task now.

The dev board I mentioned in my last post was stuck by the german post for the last 2 weeks, because there were on strike. The board is now in the custom office and I’ll collect in the next days, which will takes severals hours in Berlin.

[GSoC] coreboot for ARM64 Qemu – Week #3

For the week 3, I started to build the coreboot image to run on the target arm64 qemu. As soon as I started, I had to face a big red flag, a toolchain building error! The new toolchain (v1.31) failed to build on MacOSX. Despite several attempts, binutils failed to build and I couldn’t get the toolchain running. /buildgcc also failed on OSX due to missing string search for clang. Marc kindly help me out on this by introducing a small patch on this front. I also tried using the actual gcc and g++ (and not the innate gcc and g++ on OSX which are just symlinks to clang) but couldn’t rectify the toolchain build error.  But strangely, when I tried to build an older toolchain (v1.24) on the same machine, it worked. Confused, I decided to move forward with the build with the old toolchain itself.

I had to make some modifications on the src/mainboard/emulation/Kconfig, to bring up the new emulation mainboard. After this, I was able to successfully generate a configuration by running make menuconfig.

Next step was to make and generate the build/coreboot.rom. I have been facing some errors while building which I have been resolving on the way. The plan for this week is to finish the build. I also want to look at solving the toolchain building issue. Stepan said that the new toolchain hasn’t been tested on OSX, so this should provide some useful insights.