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firmware: qcom: scm: Expose download-mode control

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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: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>
This commit is contained in:
Bjorn Andersson
2017-08-14 15:46:18 -07:00
committed by Andy Gross
parent 4e659dbe2d
commit 8c1b7dc9ba
6 changed files with 109 additions and 0 deletions
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6
drivers/firmware/qcom_scm-32.c
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@@ -561,6 +561,12 @@ int __qcom_scm_pas_mss_reset(struct device *dev, bool reset)
return ret ? : le32_to_cpu(out);
}
int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
{
return qcom_scm_call_atomic2(QCOM_SCM_SVC_BOOT, QCOM_SCM_SET_DLOAD_MODE,
enable ? QCOM_SCM_SET_DLOAD_MODE : 0, 0);
}
int __qcom_scm_set_remote_state(struct device *dev, u32 state, u32 id)
{
struct {