linux-kernel - [PATCHv5 2/2] coresight: Do not default to CPU0 for missing CPU phandle

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Date:   Thu, 27 Jun 2019 23:45:29 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        David Brown <david.brown@...aro.org>,
        Mark Rutland <mark.rutland@....com>
Cc:     Rajendra Nayak <rnayak@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: [PATCHv5 2/2] coresight: Do not default to CPU0 for missing CPU phandle

Coresight platform support assumes that a missing "cpu" phandle
defaults to CPU0. This could be problematic and unnecessarily binds
components to CPU0, where they may not be. In coresight etm and
cpu-debug drivers, abort the probe for such cases.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 .../hwtracing/coresight/coresight-cpu-debug.c |  3 +++
 drivers/hwtracing/coresight/coresight-etm3x.c |  3 +++
 drivers/hwtracing/coresight/coresight-etm4x.c |  3 +++
 .../hwtracing/coresight/coresight-platform.c  | 20 +++++++++----------
 4 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
index 07a1367c733f..58bfd6319f65 100644
--- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
+++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
@@ -579,6 +579,9 @@ static int debug_probe(struct amba_device *adev, const struct amba_id *id)
 		return -ENOMEM;
 
 	drvdata->cpu = coresight_get_cpu(dev);
+	if (drvdata->cpu < 0)
+		return drvdata->cpu;
+
 	if (per_cpu(debug_drvdata, drvdata->cpu)) {
 		dev_err(dev, "CPU%d drvdata has already been initialized\n",
 			drvdata->cpu);
diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index 225c2982e4fe..e2cb6873c3f2 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -816,6 +816,9 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
 	}
 
 	drvdata->cpu = coresight_get_cpu(dev);
+	if (drvdata->cpu < 0)
+		return drvdata->cpu;
+
 	desc.name  = devm_kasprintf(dev, GFP_KERNEL, "etm%d", drvdata->cpu);
 	if (!desc.name)
 		return -ENOMEM;
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index 7fe266194ab5..7bcac8896fc1 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -1101,6 +1101,9 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
 	spin_lock_init(&drvdata->spinlock);
 
 	drvdata->cpu = coresight_get_cpu(dev);
+	if (drvdata->cpu < 0)
+		return drvdata->cpu;
+
 	desc.name = devm_kasprintf(dev, GFP_KERNEL, "etm%d", drvdata->cpu);
 	if (!desc.name)
 		return -ENOMEM;
diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
index 3c5ceda8db24..cf580ffbc27c 100644
--- a/drivers/hwtracing/coresight/coresight-platform.c
+++ b/drivers/hwtracing/coresight/coresight-platform.c
@@ -159,16 +159,16 @@ static int of_coresight_get_cpu(struct device *dev)
 	struct device_node *dn;
 
 	if (!dev->of_node)
-		return 0;
+		return -ENODEV;
+
 	dn = of_parse_phandle(dev->of_node, "cpu", 0);
-	/* Affinity defaults to CPU0 */
 	if (!dn)
-		return 0;
+		return -ENODEV;
+
 	cpu = of_cpu_node_to_id(dn);
 	of_node_put(dn);
 
-	/* Affinity to CPU0 if no cpu nodes are found */
-	return (cpu < 0) ? 0 : cpu;
+	return cpu;
 }
 
 /*
@@ -310,7 +310,7 @@ of_get_coresight_platform_data(struct device *dev,
 
 static inline int of_coresight_get_cpu(struct device *dev)
 {
-	return 0;
+	return -ENODEV;
 }
 #endif
 
@@ -734,14 +734,14 @@ static int acpi_coresight_get_cpu(struct device *dev)
 	struct acpi_device *adev = ACPI_COMPANION(dev);
 
 	if (!adev)
-		return 0;
+		return -ENODEV;
 	status = acpi_get_parent(adev->handle, &cpu_handle);
 	if (ACPI_FAILURE(status))
-		return 0;
+		return -ENODEV;
 
 	cpu = acpi_handle_to_logical_cpuid(cpu_handle);
 	if (cpu >= nr_cpu_ids)
-		return 0;
+		return -ENODEV;
 	return cpu;
 }
 
@@ -769,7 +769,7 @@ acpi_get_coresight_platform_data(struct device *dev,
 
 static inline int acpi_coresight_get_cpu(struct device *dev)
 {
-	return 0;
+	return -ENODEV;
 }
 #endif
 
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