linux-kernel - [PATCH] coresight: tmc-etr: Don't enable ETR when it's not ready

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Message-ID: <20230109234312.2870846-1-yabinc@google.com>
Date:   Mon,  9 Jan 2023 23:43:12 +0000
From:   Yabin Cui <yabinc@...gle.com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>
Cc:     coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Yabin Cui <yabinc@...gle.com>
Subject: [PATCH] coresight: tmc-etr: Don't enable ETR when it's not ready

Otherwise, it may cause error in AXI bus and result in a kernel panic.

Signed-off-by: Yabin Cui <yabinc@...gle.com>
---
 .../hwtracing/coresight/coresight-tmc-core.c   |  4 +++-
 .../hwtracing/coresight/coresight-tmc-etr.c    | 18 +++++++++++++++---
 drivers/hwtracing/coresight/coresight-tmc.h    |  2 +-
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 07abf28ad725..c106d142e632 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -31,7 +31,7 @@ DEFINE_CORESIGHT_DEVLIST(etb_devs, "tmc_etb");
 DEFINE_CORESIGHT_DEVLIST(etf_devs, "tmc_etf");
 DEFINE_CORESIGHT_DEVLIST(etr_devs, "tmc_etr");
 
-void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
+int tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
 {
 	struct coresight_device *csdev = drvdata->csdev;
 	struct csdev_access *csa = &csdev->access;
@@ -40,7 +40,9 @@ void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
 	if (coresight_timeout(csa, TMC_STS, TMC_STS_TMCREADY_BIT, 1)) {
 		dev_err(&csdev->dev,
 			"timeout while waiting for TMC to be Ready\n");
+		return -EBUSY;
 	}
+	return 0;
 }
 
 void tmc_flush_and_stop(struct tmc_drvdata *drvdata)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 867ad8bb9b0c..2da99dd41ed6 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -983,15 +983,21 @@ static void tmc_sync_etr_buf(struct tmc_drvdata *drvdata)
 	etr_buf->ops->sync(etr_buf, rrp, rwp);
 }
 
-static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
+static int __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
 {
 	u32 axictl, sts;
 	struct etr_buf *etr_buf = drvdata->etr_buf;
+	int rc = 0;
 
 	CS_UNLOCK(drvdata->base);
 
 	/* Wait for TMCSReady bit to be set */
-	tmc_wait_for_tmcready(drvdata);
+	rc = tmc_wait_for_tmcready(drvdata);
+	if (rc) {
+		dev_err(&drvdata->csdev->dev, "not ready ETR isn't enabled\n");
+		CS_LOCK(drvdata->base);
+		return rc;
+	}
 
 	writel_relaxed(etr_buf->size / 4, drvdata->base + TMC_RSZ);
 	writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base + TMC_MODE);
@@ -1032,6 +1038,7 @@ static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
 	tmc_enable_hw(drvdata);
 
 	CS_LOCK(drvdata->base);
+	return rc;
 }
 
 static int tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
@@ -1060,7 +1067,12 @@ static int tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
 	rc = coresight_claim_device(drvdata->csdev);
 	if (!rc) {
 		drvdata->etr_buf = etr_buf;
-		__tmc_etr_enable_hw(drvdata);
+		rc = __tmc_etr_enable_hw(drvdata);
+		if (rc) {
+			drvdata->etr_buf = NULL;
+			coresight_disclaim_device(drvdata->csdev);
+			tmc_etr_disable_catu(drvdata);
+		}
 	}
 
 	return rc;
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 66959557cf39..01c0382a29c0 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -255,7 +255,7 @@ struct tmc_sg_table {
 };
 
 /* Generic functions */
-void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata);
+int tmc_wait_for_tmcready(struct tmc_drvdata *drvdata);
 void tmc_flush_and_stop(struct tmc_drvdata *drvdata);
 void tmc_enable_hw(struct tmc_drvdata *drvdata);
 void tmc_disable_hw(struct tmc_drvdata *drvdata);
-- 
2.39.0.314.g84b9a713c41-goog