linux/Documentation/ABI/testing/sysfs-driver-ge-achc
Sebastian Reichel 0f920277dc misc: gehc-achc: new driver
General Electric Healthcare's PPD has a secondary processor from
NXP's Kinetis K20 series. That device has two SPI chip selects:

The main interface's behaviour depends on the loaded firmware
and is currently unused.

The secondary interface can be used to update the firmware using
EzPort protocol. This is implemented by this driver using the
kernel's firmware API. The firmware is being flashed into
non-volatile flash memory, so it is enough to flash it once
and not on every boot. Flashing will wear the flash memory
(it has a life time of at least 10k programming cycles). At
the same time only occasional FW updates are expected (like e.g.
a BIOS update). Thus the firmware update is triggered via sysfs
instead of doing it in the driver's probe routine like many
other drivers.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20210802172309.164365-4-sebastian.reichel@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-05 14:29:27 +02:00

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What: /sys/bus/spi/<dev>/update_firmware
Date: Jul 2021
Contact: sebastian.reichel@collabora.com
Description: Write 1 to this file to update the ACHC microcontroller
firmware via the EzPort interface. For this the kernel
will load "achc.bin" via the firmware API (so usually
from /lib/firmware). The write will block until the FW
has either been flashed successfully or an error occured.
What: /sys/bus/spi/<dev>/reset
Date: Jul 2021
Contact: sebastian.reichel@collabora.com
Description: This file represents the microcontroller's reset line.
1 means the reset line is asserted, 0 means it's not
asserted. The file is read and writable.