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Subject[PATCHv3 1/1] coresight: Do not default to CPU0 for missing CPU phandle
Date
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. Let us make the DT binding
rules a bit stricter by not defaulting to CPU0 for missing "cpu"
affinity information.

Also in coresight etm and cpu-debug drivers, abort the probe
for such cases.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
---
.../bindings/arm/coresight-cpu-debug.txt | 4 ++--
.../devicetree/bindings/arm/coresight.txt | 8 +++++---
.../hwtracing/coresight/coresight-cpu-debug.c | 3 +++
drivers/hwtracing/coresight/coresight-etm3x.c | 3 +++
drivers/hwtracing/coresight/coresight-etm4x.c | 3 +++
drivers/hwtracing/coresight/coresight-platform.c | 16 ++++++++--------
6 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
index 298291211ea4..f1de3247c1b7 100644
--- a/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
+++ b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
@@ -26,8 +26,8 @@ Required properties:
processor core is clocked by the internal CPU clock, so it
is enabled with CPU clock by default.

-- cpu : the CPU phandle the debug module is affined to. When omitted
- the module is considered to belong to CPU0.
+- cpu : the CPU phandle the debug module is affined to. Do not assume it
+ to default to CPU0 if omitted.

Optional properties:

diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
index 8a88ddebc1a2..fcc3bacfd8bc 100644
--- a/Documentation/devicetree/bindings/arm/coresight.txt
+++ b/Documentation/devicetree/bindings/arm/coresight.txt
@@ -59,6 +59,11 @@ its hardware characteristcs.

* port or ports: see "Graph bindings for Coresight" below.

+* Additional required property for Embedded Trace Macrocell (version 3.x and
+ version 4.x):
+ * cpu: the cpu phandle this ETM/PTM is affined to. Do not
+ assume it to default to CPU0 if omitted.
+
* Additional required properties for System Trace Macrocells (STM):
* reg: along with the physical base address and length of the register
set as described above, another entry is required to describe the
@@ -87,9 +92,6 @@ its hardware characteristcs.
* arm,cp14: must be present if the system accesses ETM/PTM management
registers via co-processor 14.

- * cpu: the cpu phandle this ETM/PTM is affined to. When omitted the
- source is considered to belong to CPU0.
-
* Optional property for TMC:

* arm,buffer-size: size of contiguous buffer space for TMC ETR
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..4990da2c13e9 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;
}

/*
@@ -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;
}

--
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