On 08/09/2017 01:10 PM, Bjorn Andersson wrote: > In order to aid post-mortem debugging the Qualcomm platforms provides a s/provides/provide/ > "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 somehwere in RAM, that is s/somehwere/somewhere/ > 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. > > Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> > --- > > Changes since v2: > - Define memory address by reference to TCSR > - Provide Kconfig option for defaulting to enabled > - Provided some comment in the code > > Changes since v1: > - Specify DT propert being two-cell > - Correct handling of scm-call return code > > .../devicetree/bindings/firmware/qcom,scm.txt | 2 + > drivers/firmware/Kconfig | 11 ++++ > drivers/firmware/qcom_scm-32.c | 6 ++ > drivers/firmware/qcom_scm-64.c | 13 ++++ > drivers/firmware/qcom_scm.c | 69 ++++++++++++++++++++++ > drivers/firmware/qcom_scm.h | 2 + > 6 files changed, 103 insertions(+) > > diff --git a/Documentation/devicetree/bindings/firmware/qcom,scm.txt b/Documentation/devicetree/bindings/firmware/qcom,scm.txt > index 20f26fbce875..838dba841797 100644 > --- a/Documentation/devicetree/bindings/firmware/qcom,scm.txt > +++ b/Documentation/devicetree/bindings/firmware/qcom,scm.txt > @@ -18,6 +18,8 @@ Required properties: > * Core, iface, and bus clocks required for "qcom,scm" > - clock-names: Must contain "core" for the core clock, "iface" for the interface > clock and "bus" for the bus clock per the requirements of the compatible. > +- qcom,dload-mode: phandle reference to the TCSR hardware block containing the > + download mode control register (optional) > > Example for MSM8916: > > diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig > index 6e4ed5a9c6fd..ed23c77d6361 100644 > --- a/drivers/firmware/Kconfig > +++ b/drivers/firmware/Kconfig > @@ -215,6 +215,17 @@ config QCOM_SCM_64 > def_bool y > depends on QCOM_SCM && ARM64 > > +config QCOM_SCM_DOWNLOAD_MODE_DEFAULT > + bool "Qualcomm Download mode enabled by default" Decapitalize download? > + depends on QCOM_SCM > + help > + A device with "download mode" enabled will upon an unexpected > + warm-restart enter a special debug mode that allows the user to > + "download" memory content over USB for offline postmortem analysis. > + The feature can be enabled/disabled on the kernel command line. > + > + Say Y here to enable "download mode" by default. > + otherwise Reviewed-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
