From: Tingwei Zhang tingwei@codeaurora.org

On some Qualcomm Technologies Inc. SoCs like SC7180, there exists a hardware errata where the APSS (Application Processor SubSystem)/CPU watchdog counter is stopped when the trace unit power up ETM register is set (TRCPDCR.PU = 1). Since the ETMs share the same power domain as that of respective CPU cores, they are powered on when the CPU core is powered on. So we can skip powering up of trace unit after checking for this errata via new property called "qcom,skip-power-up".

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 --- drivers/hwtracing/coresight/coresight-etm4x.c | 27 ++++++++++++------- drivers/hwtracing/coresight/coresight-etm4x.h | 3 +++ 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c index fb0f5f4f3a91..c16532e1e968 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.c +++ b/drivers/hwtracing/coresight/coresight-etm4x.c @@ -196,12 +196,14 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) writel_relaxed(config->vmid_mask0, drvdata->base + TRCVMIDCCTLR0); writel_relaxed(config->vmid_mask1, drvdata->base + TRCVMIDCCTLR1);

- /* - * Request to keep the trace unit powered and also - * emulation of powerdown - */ - writel_relaxed(readl_relaxed(drvdata->base + TRCPDCR) | TRCPDCR_PU, - drvdata->base + TRCPDCR); + if (!drvdata->skip_power_up) { + /* + * Request to keep the trace unit powered and also + * emulation of powerdown + */ + writel_relaxed(readl_relaxed(drvdata->base + TRCPDCR) | + TRCPDCR_PU, drvdata->base + TRCPDCR); + }

/* Enable the trace unit */ writel_relaxed(1, drvdata->base + TRCPRGCTLR); @@ -476,10 +478,12 @@ static void etm4_disable_hw(void *info)

CS_UNLOCK(drvdata->base);

- /* power can be removed from the trace unit now */ - control = readl_relaxed(drvdata->base + TRCPDCR); - control &= ~TRCPDCR_PU; - writel_relaxed(control, drvdata->base + TRCPDCR); + if (!drvdata->skip_power_up) { + /* power can be removed from the trace unit now */ + control = readl_relaxed(drvdata->base + TRCPDCR); + control &= ~TRCPDCR_PU; + writel_relaxed(control, drvdata->base + TRCPDCR); + }

control = readl_relaxed(drvdata->base + TRCPRGCTLR);

@@ -1429,6 +1433,9 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) return -ENOMEM; }

+ if (fwnode_property_present(dev_fwnode(dev), "qcom,skip-power-up")) + drvdata->skip_power_up = true; + /* Validity for the resource is already checked by the AMBA core */ base = devm_ioremap_resource(dev, res); if (IS_ERR(base)) diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index 4a695bf90582..72c9a55e67df 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -407,6 +407,8 @@ struct etmv4_save_state { * @config: structure holding configuration parameters. * @save_state: State to be preserved across power loss * @state_needs_restore: True when there is context to restore after PM exit + * @skip_power_up: Indicates if an implementation can skip powering up + * the trace unit. */ struct etmv4_drvdata { void __iomem *base; @@ -454,6 +456,7 @@ struct etmv4_drvdata { struct etmv4_config config; struct etmv4_save_state *save_state; bool state_needs_restore; + bool skip_power_up; };

/* Address comparator access types */

On Fri, 15 May 2020 at 10:23, Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org wrote:

From: Tingwei Zhang tingwei@codeaurora.org

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

---

Documentation/devicetree/bindings/arm/coresight.txt | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt index 846f6daae71b..e4b2eda0b53b 100644 --- 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:

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

    * arm,buffer-size: size of contiguous buffer space for TMC ETR

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