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Message-Id: <20220809223401.24599-6-mike.leach@linaro.org>
Date:   Tue,  9 Aug 2022 23:33:53 +0100
From:   Mike Leach <mike.leach@...aro.org>
To:     coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     mathieu.poirier@...aro.org, suzuki.poulose@....com,
        peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        linux-perf-users@...r.kernel.org, leo.yan@...aro.org,
        quic_jinlmao@...cinc.com, Mike Leach <mike.leach@...aro.org>
Subject: [PATCH v3 05/13] coresight: etm3x: Update ETM3 driver to use Trace ID API

Use the TraceID API to allocate ETM trace IDs dynamically.

As with the etm4x we allocate on enable / disable for perf,
allocate on enable / reset for sysfs.

Additionally we allocate on sysfs file read as both perf and sysfs
can read the ID before enabling the hardware.

Remove sysfs option to write trace ID - which is inconsistent with
both the dynamic allocation method and the fixed allocation method
previously used.

Signed-off-by: Mike Leach <mike.leach@...aro.org>
---
 drivers/hwtracing/coresight/coresight-etm.h   |  2 +
 .../coresight/coresight-etm3x-core.c          | 77 +++++++++++++++++--
 .../coresight/coresight-etm3x-sysfs.c         | 27 ++-----
 3 files changed, 79 insertions(+), 27 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h
index f3ab96eaf44e..3667428d38b6 100644
--- a/drivers/hwtracing/coresight/coresight-etm.h
+++ b/drivers/hwtracing/coresight/coresight-etm.h
@@ -287,4 +287,6 @@ int etm_get_trace_id(struct etm_drvdata *drvdata);
 void etm_set_default(struct etm_config *config);
 void etm_config_trace_mode(struct etm_config *config);
 struct etm_config *get_etm_config(struct etm_drvdata *drvdata);
+int etm_read_alloc_trace_id(struct etm_drvdata *drvdata);
+void etm_release_trace_id(struct etm_drvdata *drvdata);
 #endif
diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
index d0ab9933472b..c4e7b3337a5c 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
@@ -32,6 +32,7 @@
 
 #include "coresight-etm.h"
 #include "coresight-etm-perf.h"
+#include "coresight-trace-id.h"
 
 /*
  * Not really modular but using module_param is the easiest way to
@@ -490,18 +491,67 @@ static int etm_trace_id(struct coresight_device *csdev)
 	return etm_get_trace_id(drvdata);
 }
 
+int etm_read_alloc_trace_id(struct etm_drvdata *drvdata)
+{
+	int trace_id;
+
+	/* trace id function has its own lock */
+	trace_id = coresight_trace_id_get_cpu_id(drvdata->cpu);
+	if (IS_VALID_ID(trace_id))
+		drvdata->traceid = (u8)trace_id;
+	else
+		dev_err(&drvdata->csdev->dev,
+			"Failed to allocate trace ID for %s on CPU%d\n",
+			dev_name(&drvdata->csdev->dev), drvdata->cpu);
+	return trace_id;
+}
+
+static int etm_set_current_trace_id(struct etmv4_drvdata *drvdata)
+{
+	int trace_id;
+
+	/*
+	 * Set the currently allocated trace ID - perf allocates IDs
+	 * as part of setup_aux for all CPUs it may use.
+	 */
+	trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu);
+	if (IS_VALID_ID(trace_id)) {
+		drvdata->traceid = (u8)trace_id;
+		return 0;
+	}
+
+	dev_err(&drvdata->csdev->dev, "Failed to set trace ID for %s on CPU%d\n",
+		dev_name(&drvdata->csdev->dev), drvdata->cpu);
+
+	return -EINVAL;
+}
+
+void etm_release_trace_id(struct etm_drvdata *drvdata)
+{
+	coresight_trace_id_put_cpu_id(drvdata->cpu);
+}
+
 static int etm_enable_perf(struct coresight_device *csdev,
 			   struct perf_event *event)
 {
 	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+	int ret;
 
 	if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
 		return -EINVAL;
 
 	/* Configure the tracer based on the session's specifics */
 	etm_parse_event_config(drvdata, event);
+
+	/* perf allocates cpu IDs in setup aux - set the current on device */
+	ret = etm_set_current_trace_id(drvdata);
+	if (ret < 0)
+		return ret;
+
 	/* And enable it */
-	return etm_enable_hw(drvdata);
+	ret = etm_enable_hw(drvdata);
+
+	return ret;
 }
 
 static int etm_enable_sysfs(struct coresight_device *csdev)
@@ -512,6 +562,11 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
 
 	spin_lock(&drvdata->spinlock);
 
+	/* sysfs needs to allocate and set a trace ID */
+	ret = etm_read_alloc_trace_id(drvdata);
+	if (ret < 0)
+		goto unlock_enable_sysfs;
+
 	/*
 	 * Configure the ETM only if the CPU is online.  If it isn't online
 	 * hw configuration will take place on the local CPU during bring up.
@@ -528,6 +583,10 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
 		ret = -ENODEV;
 	}
 
+	if (ret)
+		etm_release_trace_id(drvdata);
+
+unlock_enable_sysfs:
 	spin_unlock(&drvdata->spinlock);
 
 	if (!ret)
@@ -611,6 +670,9 @@ static void etm_disable_perf(struct coresight_device *csdev)
 	coresight_disclaim_device_unlocked(csdev);
 
 	CS_LOCK(drvdata->base);
+
+	/* The perf event will release trace ids when it is destroyed */
+
 }
 
 static void etm_disable_sysfs(struct coresight_device *csdev)
@@ -635,6 +697,13 @@ static void etm_disable_sysfs(struct coresight_device *csdev)
 	spin_unlock(&drvdata->spinlock);
 	cpus_read_unlock();
 
+	/*
+	 * we only release trace IDs when resetting sysfs.
+	 * This permits sysfs users to read the trace ID after the trace
+	 * session has completed. This maintains operational behaviour with
+	 * prior trace id allocation method
+	 */
+
 	dev_dbg(&csdev->dev, "ETM tracing disabled\n");
 }
 
@@ -781,11 +850,6 @@ static void etm_init_arch_data(void *info)
 	CS_LOCK(drvdata->base);
 }
 
-static void etm_init_trace_id(struct etm_drvdata *drvdata)
-{
-	drvdata->traceid = coresight_get_trace_id(drvdata->cpu);
-}
-
 static int __init etm_hp_setup(void)
 {
 	int ret;
@@ -871,7 +935,6 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
 	if (etm_arch_supported(drvdata->arch) == false)
 		return -EINVAL;
 
-	etm_init_trace_id(drvdata);
 	etm_set_default(&drvdata->config);
 
 	pdata = coresight_get_platform_data(dev);
diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
index 68fcbf4ce7a8..fde028e43c92 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
@@ -85,6 +85,7 @@ static ssize_t reset_store(struct device *dev,
 		}
 
 		etm_set_default(config);
+		etm_release_trace_id(drvdata);
 		spin_unlock(&drvdata->spinlock);
 	}
 
@@ -1189,30 +1190,16 @@ static DEVICE_ATTR_RO(cpu);
 static ssize_t traceid_show(struct device *dev,
 			    struct device_attribute *attr, char *buf)
 {
-	unsigned long val;
-	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
-
-	val = etm_get_trace_id(drvdata);
-
-	return sprintf(buf, "%#lx\n", val);
-}
-
-static ssize_t traceid_store(struct device *dev,
-			     struct device_attribute *attr,
-			     const char *buf, size_t size)
-{
-	int ret;
-	unsigned long val;
+	int trace_id;
 	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
 
-	ret = kstrtoul(buf, 16, &val);
-	if (ret)
-		return ret;
+	trace_id = etm_read_alloc_trace_id(drvdata);
+	if (trace_id < 0)
+		return trace_id;
 
-	drvdata->traceid = val & ETM_TRACEID_MASK;
-	return size;
+	return sysfs_emit(buf, "%#x\n", trace_id);
 }
-static DEVICE_ATTR_RW(traceid);
+static DEVICE_ATTR_RO(traceid);
 
 static struct attribute *coresight_etm_attrs[] = {
 	&dev_attr_nr_addr_cmp.attr,
-- 
2.17.1

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