dt-bindings: arm: coresight: Add support to skip trace unit power up

Add "qcom,skip-power-up" property to identify systems which can
skip powering up of trace unit since they share the same power
domain as their CPU core. This is required to identify such
systems with hardware errata which stops the CPU watchdog counter
when the power up bit is set (TRCPDCR.PU).

Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Co-developed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200716175746.3338735-5-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
index 846f6daae71b29e0e5f0d65c0f5f16f0ef1a6b9d..e4b2eda0b53b977cba335a553c43200db9070d33 100644 (file)
--- a/Documentation/devicetree/bindings/arm/coresight.txt
+++ b/Documentation/devicetree/bindings/arm/coresight.txt
@@ -108,6 +108,13 @@ its hardware characteristcs.
        * arm,cp14: must be present if the system accesses ETM/PTM management
          registers via co-processor 14.
 
+       * qcom,skip-power-up: boolean. Indicates that an implementation can
+         skip powering up the trace unit. TRCPDCR.PU does not have to be set
+         on Qualcomm Technologies Inc. systems since ETMs are in the same power
+         domain as their CPU cores. This property is required to identify such
+         systems with hardware errata where the CPU watchdog counter is stopped
+         when TRCPDCR.PU is set.
+
 * Optional property for TMC:
 
        * arm,buffer-size: size of contiguous buffer space for TMC ETR