linux-kernel - [PATCHv3 1/2] coresight: replicator: Reset replicator if context is lost

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Message-Id: <64b324cd144377d2ce9a09bd728656a721936046.1590171891.git.saiprakash.ranjan@codeaurora.org>
Date:   Sat, 23 May 2020 00:06:51 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>, devicetree@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: [PATCHv3 1/2] coresight: replicator: Reset replicator if context is lost

On some QCOM SoCs, replicators in Always-On domain loses its
context as soon as the clock is disabled. Currently as a part
of pm_runtime workqueue, clock is disabled after the replicator
is initialized by amba_pm_runtime_suspend assuming that context
is not lost which is not true for replicators with such
limitations. So add a new property "qcom,replicator-loses-context"
to identify such replicators and reset them.

Suggested-by: Mike Leach <mike.leach@...aro.org>
Reviewed-by: Mike Leach <mike.leach@...aro.org>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
---
 .../coresight/coresight-replicator.c          | 55 +++++++++++++------
 1 file changed, 38 insertions(+), 17 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
index e7dc1c31d20d..9d3a8f915784 100644
--- a/drivers/hwtracing/coresight/coresight-replicator.c
+++ b/drivers/hwtracing/coresight/coresight-replicator.c
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/pm_runtime.h>
+#include <linux/property.h>
 #include <linux/clk.h>
 #include <linux/of.h>
 #include <linux/coresight.h>
@@ -32,12 +33,14 @@ DEFINE_CORESIGHT_DEVLIST(replicator_devs, "replicator");
  * @atclk:	optional clock for the core parts of the replicator.
  * @csdev:	component vitals needed by the framework
  * @spinlock:	serialize enable/disable operations.
+ * @check_idfilter_val: check if the context is lost upon clock removal.
  */
 struct replicator_drvdata {
 	void __iomem		*base;
 	struct clk		*atclk;
 	struct coresight_device	*csdev;
 	spinlock_t		spinlock;
+	bool			check_idfilter_val;
 };
 
 static void dynamic_replicator_reset(struct replicator_drvdata *drvdata)
@@ -66,29 +69,43 @@ static int dynamic_replicator_enable(struct replicator_drvdata *drvdata,
 				     int inport, int outport)
 {
 	int rc = 0;
-	u32 reg;
-
-	switch (outport) {
-	case 0:
-		reg = REPLICATOR_IDFILTER0;
-		break;
-	case 1:
-		reg = REPLICATOR_IDFILTER1;
-		break;
-	default:
-		WARN_ON(1);
-		return -EINVAL;
-	}
+	u32 id0val, id1val;
 
 	CS_UNLOCK(drvdata->base);
 
-	if ((readl_relaxed(drvdata->base + REPLICATOR_IDFILTER0) == 0xff) &&
-	    (readl_relaxed(drvdata->base + REPLICATOR_IDFILTER1) == 0xff))
+	id0val = readl_relaxed(drvdata->base + REPLICATOR_IDFILTER0);
+	id1val = readl_relaxed(drvdata->base + REPLICATOR_IDFILTER1);
+
+	/*
+	 * Some replicator designs lose context when AMBA clocks are removed,
+	 * so have a check for this.
+	 */
+	if (drvdata->check_idfilter_val && id0val == 0x0 && id1val == 0x0)
+		id0val = id1val = 0xff;
+
+	if (id0val == 0xff && id1val == 0xff)
 		rc = coresight_claim_device_unlocked(drvdata->base);
 
+	if (!rc) {
+		switch (outport) {
+		case 0:
+			id0val = 0x0;
+			break;
+		case 1:
+			id1val = 0x0;
+			break;
+		default:
+			WARN_ON(1);
+			rc = -EINVAL;
+		}
+	}
+
 	/* Ensure that the outport is enabled. */
-	if (!rc)
-		writel_relaxed(0x00, drvdata->base + reg);
+	if (!rc) {
+		writel_relaxed(id0val, drvdata->base + REPLICATOR_IDFILTER0);
+		writel_relaxed(id1val, drvdata->base + REPLICATOR_IDFILTER1);
+	}
+
 	CS_LOCK(drvdata->base);
 
 	return rc;
@@ -239,6 +256,10 @@ static int replicator_probe(struct device *dev, struct resource *res)
 		desc.groups = replicator_groups;
 	}
 
+	if (fwnode_property_present(dev_fwnode(dev),
+				    "qcom,replicator-loses-context"))
+		drvdata->check_idfilter_val = true;
+
 	dev_set_drvdata(dev, drvdata);
 
 	pdata = coresight_get_platform_data(dev);
-- 
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