• Bjorn Andersson's avatar
    firmware: qcom: scm: Expose download-mode control · 8c1b7dc9
    Bjorn Andersson authored
    In order to aid post-mortem debugging the Qualcomm platforms provide a
    "memory download mode", where the boot loader will provide an interface
    for custom tools to "download" the content of RAM to a host machine.
    The mode is triggered by writing a magic value somewhere in RAM, that is
    read in the boot code path after a warm-restart. Two mechanism for
    setting this magic value are supported in modern platforms; a direct SCM
    call to enable the mode or through a secure io write of a magic value.
    In order for a normal reboot not to trigger "download mode" the magic
    must be cleared during a clean reboot.
    Download mode has to be enabled by including qcom_scm.download_mode=1 on
    the command line.
    Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
    Signed-off-by: default avatarBjorn Andersson <bjorn.andersson@linaro.org>
    Signed-off-by: default avatarAndy Gross <andy.gross@linaro.org>
qcom,scm.txt 1.32 KB