coresight: Support panic kdump functionality

After kernel panic happens, coresight has many useful info can be used
for analysis.  For example, the trace info from ETB RAM can be used to
check the CPU execution flows before crash.  So we can save the tracing
data from sink devices, and rely on kdump to save DDR content and uses
"crash" tool to extract coresight dumping from vmcore file.

This patch is to add a simple framework to support panic dump
functionality; it registers panic notifier, and provide the general APIs
{coresight_kdump_add|coresight_kdump_del} as helper functions so any
coresight device can add itself into dump list or delete as needed.

This driver provides helper function coresight_kdump_update() to update
the dump buffer base address and buffer size.  This function can be used
by coresight driver, e.g. it can be used to save ETM meta data info at
runtime and these info can be prepared pre panic happening.

When kernel panic happens, the notifier iterates dump list and calls
callback function to dump device specific info.  The panic dump is
mainly used to dump trace data so we can get to know the execution flow
before the panic happens.

Signed-off-by: Leo Yan <leo.yan@linaro.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 61db9dd0d571f..946fe19736eaf 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
 obj-$(CONFIG_CORESIGHT_DYNAMIC_REPLICATOR) += coresight-dynamic-replicator.o
 obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
 obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
+obj-$(CONFIG_CORESIGHT_PANIC_KDUMP) += coresight-panic-kdump.o