7 files changed, 76 insertions, 17 deletions

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h
index 371fb7d2e829..5b29d5540fe5 100644
--- a/drivers/hwtracing/coresight/coresight-etm.h
+++ b/drivers/hwtracing/coresight/coresight-etm.h
@@ -13,6 +13,7 @@
 #ifndef _CORESIGHT_CORESIGHT_ETM_H
 #define _CORESIGHT_CORESIGHT_ETM_H
 
+#include <asm/local.h>
 #include <linux/spinlock.h>
 #include "coresight-priv.h"
 
@@ -214,7 +215,7 @@ struct etm_config {
  * @port_size:	port size as reported by ETMCR bit 4-6 and 21.
  * @arch:	ETM/PTM version number.
  * @use_cpu14:	true if management registers need to be accessed via CP14.
- * @enable:	is this ETM/PTM currently tracing.
+ * @mode:	this tracer's mode, i.e sysFS, Perf or disabled.
  * @sticky_enable: true if ETM base configuration has been done.
  * @boot_enable:true if we should start tracing at boot time.
  * @os_unlock:	true if access to management registers is allowed.
@@ -238,7 +239,7 @@ struct etm_drvdata {
 	int				port_size;
 	u8				arch;
 	bool				use_cp14;
-	bool				enable;
+	local_t				mode;
 	bool				sticky_enable;
 	bool				boot_enable;
 	bool				os_unlock;
diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
index 456df2378a6f..387c79fd9d5e 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
@@ -716,7 +716,7 @@ static ssize_t cntr_val_show(struct device *dev,
 	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
 	struct etm_config *config = &drvdata->config;
 
-	if (!drvdata->enable) {
+	if (!local_read(&drvdata->mode)) {
 		spin_lock(&drvdata->spinlock);
 		for (i = 0; i < drvdata->nr_cntr; i++)
 			ret += sprintf(buf, "counter %d: %x\n",
@@ -935,7 +935,7 @@ static ssize_t seq_curr_state_show(struct device *dev,
 	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
 	struct etm_config *config = &drvdata->config;
 
-	if (!drvdata->enable) {
+	if (!local_read(&drvdata->mode)) {
 		val = config->seq_curr_state;
 		goto out;
 	}
diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index 1952dc31fee4..e16501b41ed8 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -306,7 +306,7 @@ int etm_get_trace_id(struct etm_drvdata *drvdata)
 	if (!drvdata)
 		goto out;
 
-	if (!drvdata->enable)
+	if (!local_read(&drvdata->mode))
 		return drvdata->traceid;
 
 	pm_runtime_get_sync(drvdata->dev);
@@ -332,7 +332,7 @@ static int etm_trace_id(struct coresight_device *csdev)
 	return etm_get_trace_id(drvdata);
 }
 
-static int etm_enable(struct coresight_device *csdev)
+static int etm_enable_sysfs(struct coresight_device *csdev)
 {
 	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	int ret;
@@ -351,18 +351,44 @@ static int etm_enable(struct coresight_device *csdev)
 			goto err;
 	}
 
-	drvdata->enable = true;
 	drvdata->sticky_enable = true;
-
 	spin_unlock(&drvdata->spinlock);
 
 	dev_info(drvdata->dev, "ETM tracing enabled\n");
 	return 0;
+
 err:
 	spin_unlock(&drvdata->spinlock);
 	return ret;
 }
 
+static int etm_enable(struct coresight_device *csdev, u32 mode)
+{
+	int ret;
+	u32 val;
+	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	val = local_cmpxchg(&drvdata->mode, CS_MODE_DISABLED, mode);
+
+	/* Someone is already using the tracer */
+	if (val)
+		return -EBUSY;
+
+	switch (mode) {
+	case CS_MODE_SYSFS:
+		ret = etm_enable_sysfs(csdev);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	/* The tracer didn't start */
+	if (ret)
+		local_set(&drvdata->mode, CS_MODE_DISABLED);
+
+	return ret;
+}
+
 static void etm_disable_hw(void *info)
 {
 	int i;
@@ -387,7 +413,7 @@ static void etm_disable_hw(void *info)
 	dev_dbg(drvdata->dev, "cpu: %d disable smp call done\n", drvdata->cpu);
 }
 
-static void etm_disable(struct coresight_device *csdev)
+static void etm_disable_sysfs(struct coresight_device *csdev)
 {
 	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -405,7 +431,6 @@ static void etm_disable(struct coresight_device *csdev)
 	 * ensures that register writes occur when cpu is powered.
 	 */
 	smp_call_function_single(drvdata->cpu, etm_disable_hw, drvdata, 1);
-	drvdata->enable = false;
 
 	spin_unlock(&drvdata->spinlock);
 	put_online_cpus();
@@ -413,6 +438,33 @@ static void etm_disable(struct coresight_device *csdev)
 	dev_info(drvdata->dev, "ETM tracing disabled\n");
 }
 
+static void etm_disable(struct coresight_device *csdev)
+{
+	u32 mode;
+	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	/*
+	 * For as long as the tracer isn't disabled another entity can't
+	 * change its status.  As such we can read the status here without
+	 * fearing it will change under us.
+	 */
+	mode = local_read(&drvdata->mode);
+
+	switch (mode) {
+	case CS_MODE_DISABLED:
+		break;
+	case CS_MODE_SYSFS:
+		etm_disable_sysfs(csdev);
+		break;
+	default:
+		WARN_ON_ONCE(mode);
+		return;
+	}
+
+	if (mode)
+		local_set(&drvdata->mode, CS_MODE_DISABLED);
+}
+
 static const struct coresight_ops_source etm_source_ops = {
 	.cpu_id		= etm_cpu_id,
 	.trace_id	= etm_trace_id,
@@ -440,7 +492,7 @@ static int etm_cpu_callback(struct notifier_block *nfb, unsigned long action,
 			etmdrvdata[cpu]->os_unlock = true;
 		}
 
-		if (etmdrvdata[cpu]->enable)
+		if (local_read(&etmdrvdata[cpu]->mode))
 			etm_enable_hw(etmdrvdata[cpu]);
 		spin_unlock(&etmdrvdata[cpu]->spinlock);
 		break;
@@ -453,7 +505,7 @@ static int etm_cpu_callback(struct notifier_block *nfb, unsigned long action,
 
 	case CPU_DYING:
 		spin_lock(&etmdrvdata[cpu]->spinlock);
-		if (etmdrvdata[cpu]->enable)
+		if (local_read(&etmdrvdata[cpu]->mode))
 			etm_disable_hw(etmdrvdata[cpu]);
 		spin_unlock(&etmdrvdata[cpu]->spinlock);
 		break;
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index c2f518fbc9a8..0026092fec7f 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -187,7 +187,7 @@ static void etm4_enable_hw(void *info)
 	dev_dbg(drvdata->dev, "cpu: %d enable smp call done\n", drvdata->cpu);
 }
 
-static int etm4_enable(struct coresight_device *csdev)
+static int etm4_enable(struct coresight_device *csdev, u32 mode)
 {
 	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	int ret;
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 14f245a2018d..ed116b303e87 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -34,6 +34,12 @@
 #define TIMEOUT_US		100
 #define BMVAL(val, lsb, msb)	((val & GENMASK(msb, lsb)) >> lsb)
 
+enum cs_mode {
+	CS_MODE_DISABLED,
+	CS_MODE_SYSFS,
+	CS_MODE_PERF,
+};
+
 static inline void CS_LOCK(void __iomem *addr)
 {
 	do {
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 6b44928c1076..b20afb709141 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -222,7 +222,7 @@ static void coresight_disable_link(struct coresight_device *csdev,
 	csdev->enable = false;
 }
 
-static int coresight_enable_source(struct coresight_device *csdev)
+static int coresight_enable_source(struct coresight_device *csdev, u32 mode)
 {
 	int ret;
 
@@ -234,7 +234,7 @@ static int coresight_enable_source(struct coresight_device *csdev)
 
 	if (!csdev->enable) {
 		if (source_ops(csdev)->enable) {
-			ret = source_ops(csdev)->enable(csdev);
+			ret = source_ops(csdev)->enable(csdev, mode);
 			if (ret)
 				return ret;
 		}
@@ -458,7 +458,7 @@ int coresight_enable(struct coresight_device *csdev)
 	if (ret)
 		goto err_path;
 
-	ret = coresight_enable_source(csdev);
+	ret = coresight_enable_source(csdev, CS_MODE_SYSFS);
 	if (ret)
 		goto err_source;
 
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 851ecb22397e..61dfb8d511ea 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -213,7 +213,7 @@ struct coresight_ops_link {
 struct coresight_ops_source {
 	int (*cpu_id)(struct coresight_device *csdev);
 	int (*trace_id)(struct coresight_device *csdev);
-	int (*enable)(struct coresight_device *csdev);
+	int (*enable)(struct coresight_device *csdev, u32 mode);
 	void (*disable)(struct coresight_device *csdev);
 };