Flashing a BIOS chip with a Raspberry Pi

I made this post as a addition or supplement to my “Flashing a BIOS chip with an Arduino” post.

While doing some research online I found several articles/posts from people using a Raspberry Pi to flash SPI flash chips. Apparently the Raspberry Pi  is very suitable for this kind of thing as it has a SPI interface and is able to run linux. I was eager to try this out for myself so I got out my Pi 3 model B and got to work. For this project I used a Winbond 25X80 salvaged from a motherboard I had lying around.

Preparing the RaspberryPi

I’ve tried different versions of Raspbian but Jessie lite seems to works best for me. It is available for download here: https://downloads.raspberrypi.org/raspbian_lite/images/raspbian_lite-2017-07-05/

Install the packages needed by flashrom by using the following command:

sudo apt-get install pciutils libpci-dev libusb-1.0 libusb-dev git

Build and install flashrom using the commands below:

git clone https://github.com/flashrom/flashrom.git
cd flashrom
make && make install

Before continuing we need to enable the SPI interfaces on the Raspberry Pi. This can be done either by editing the config file found at /boot/config.txt and uncommenting the line that says #dtparam=spi=on or by using raspi-config. Run raspi-config, and under interfaces enable SPI.

After rebooting the SPI interfaces are available under /dev/spidev0.0 and /dev/spidev0.1.

Connecting the Raspberry to the SPI flash chip

The table below show the connections between the RaspberryPi and the chip.

RPi pin SPI flash
25 GND
24 CS
23 SCK
21 DO
19 DI
17 VCC 3.3V and /HOLD and /WP

In order to verify flashrom is working correctly and the chip is detected properly we run flashrom without any operation. Example output can be found below:

pi@raspberrypi:~ $ flashrom -p linux_spi:dev=/dev/spidev0.1
flashrom v0.9.9-91-g0bfa819 on Linux 4.9.35-v7+ (arm7l)
flashrom is free software, get the source code at https://flashrom.org

Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns). 
Found Winbond flash chip "W25X80" (1024 kB, SPI) on linux_spi. 
No operations were specified.

Now that we have verified everything is in order we can start writing the BIOS to the chip:

pi@raspberrypi:~ $ flashrom -p linux_spi:dev=/dev/spidev0.1 -w YOURBIOS
flashrom v0.9.9-91-g0bfa819 on Linux 4.9.35-v7+ (armv7l)
flashrom is free software, get the source code at https://flashrom.org

Using clock_gettime for delay loops (clk_id: 1, resolution: 1ns).
Found Winbond flash chip "W25X80" (1024 kB, SPI) on linux_spi.
Reading old flash chip contents... done.
Erasing and writing flash chip... Erase/write done.
Verifying flash... VERIFIED.

And that is that.

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