• Hans de Goede's avatar
    firmware: Add new platform fallback mechanism and firmware_request_platform() · e4c2c0ff
    Hans de Goede authored
    In some cases the platform's main firmware (e.g. the UEFI fw) may contain
    an embedded copy of device firmware which needs to be (re)loaded into the
    peripheral. Normally such firmware would be part of linux-firmware, but in
    some cases this is not feasible, for 2 reasons:
    
    1) The firmware is customized for a specific use-case of the chipset / use
    with a specific hardware model, so we cannot have a single firmware file
    for the chipset. E.g. touchscreen controller firmwares are compiled
    specifically for the hardware model they are used with, as they are
    calibrated for a specific model digitizer.
    
    2) Despite repeated attempts we have failed to get permission to
    redistribute the firmware. This is especially a problem with customized
    firmwares, these get created by the chip vendor for a specific ODM and the
    copyright may partially belong with the ODM, so the chip vendor cannot
    give a blanket permission to distribute these.
    
    This commit adds a new platform fallback mechanism to the firmware loader
    which will try to lookup a device fw copy embedded in the platform's main
    firmware if direct filesystem lookup fails.
    
    Drivers which need such embedded fw copies can enable this fallback
    mechanism by using the new firmware_request_platform() function.
    
    Note that for now this is only supported on EFI platforms and even on
    these platforms firmware_fallback_platform() only works if
    CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers
    which need this), in all other cases firmware_fallback_platform() simply
    always returns -ENOENT.
    Reported-by: default avatarDave Olsthoorn <dave@bewaar.me>
    Suggested-by: default avatarPeter Jones <pjones@redhat.com>
    Acked-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Link: https://lore.kernel.org/r/20200115163554.101315-5-hdegoede@redhat.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    e4c2c0ff
main.c 36.1 KB