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Old doc: https://wiki.flashrom.org/RaspberryPi Change-Id: Ie3b7f2ed31f0b756815de055a2c58602263dac66 Signed-off-by: Anastasia Klimchuk <aklm@flashrom.org> Reviewed-on: https://review.coreboot.org/c/flashrom/+/86312 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
57 lines
2.4 KiB
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57 lines
2.4 KiB
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===========
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RaspberryPi
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===========
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`RaspberryPi <http://www.raspberrypi.org/faqs>`_ is a cheap single-board computer developed in the UK
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by the Raspberry Pi Foundation with the intention of stimulating the teaching of basic computer science in schools.
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It can run a fully-functional GNU/Linux distribution and exposes SPI, I2C and several GPIOs on its expansion header.
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Prerequisites
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=============
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Use latest Raspbian (or any other distribution with a recent kernel).
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Run the following commands (or make sure these kernel modules are loaded successfully)::
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modprobe spi_bcm2835 # If that fails you may wanna try the older spi_bcm2708 module instead
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modprobe spidev
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Connecting the flash chip
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=========================
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To learn more about the RPi's expansion header refer to http://elinux.org/Rpi_Low-level_peripherals .
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If you use one of the first A or B models, please make sure to not draw more than 50mA from the 3.3V pin.
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Official numbers for newer models are hard to find but they use a switching regulator
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that should provide a much higher margin. If the flash chip is still placed in a foreign circuit
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(e.g. soldered to a PC mainboard) please refer to :doc:`/user_docs/in_system` for further details.
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========== =======================
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RPi header SPI flash
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========== =======================
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25 GND
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24 /CS
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23 SCK
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21 DO
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19 DI
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17 VCC 3.3V (+ /HOLD, /WP)
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========== =======================
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.. container:: danger, admonition
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Always connect all input pins of integrated circuits (not only flash chips).
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In general the other pins (usually pin 3 is /WP and pin 7 is /HOLD) should be connected to Vcc
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unless they are required to be floating or connected to GND (both extremely uncommon for SPI flash chips).
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Please consult the datasheet for the flash chip in question.
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If your flash chip is detected but your read/write/verify operations tend to fail, try to add decoupling capacitors (one 100nF and one 4.7uF ceramic capacitor is preferred) close to the flash chip's power pin.
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Running flashrom
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================
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Flashrom uses the Linux-native SPI driver, which is implemented by flashrom's linux_spi programmer.
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To use the RaspberryPi with flashrom, you have to specify that programmer. You should always tell
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it at what speed the SPI bus should run; you specify that with the spispeed parameter (given in kHz).
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You also have to specify the Linux SPI device, e.g.::
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flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=1000
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