coresight: adding path for STM device

>From a core framework point of view an STM device is a source that is
treated the same way as any other tracers.  Unlike tracers though STM
devices are not associated with a CPU.  As such it doesn't make sense
to associate the path from an STM device to its sink with a per-cpu
variable as it is done for tracers.

This patch simply adds another global variable to keep STM paths and the
processing in coresight_enable/disable() is updated to deal with STM
devices properly.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit a685d68328f14579b2e68d6a3a2066089cffbf98)

diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 945bc31f0ec55128c9c15d986aad9d8f38738167..0995df8f85bc543f260138f7ab3cf4bf5ef59025 100644 (file)
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -43,7 +43,15 @@ struct coresight_node {
  * When operating Coresight drivers from the sysFS interface, only a single
  * path can exist from a tracer (associated to a CPU) to a sink.
  */
-static DEFINE_PER_CPU(struct list_head *, sysfs_path);
+static DEFINE_PER_CPU(struct list_head *, tracer_path);
+
+/*
+ * As of this writing only a single STM can be found in CS topologies.  Since
+ * there is no way to know if we'll ever see more and what kind of
+ * configuration they will enact, for the time being only define a single path
+ * for STM.
+ */
+static struct list_head *stm_path;
 
 static int coresight_id_match(struct device *dev, void *data)
 {
@@ -432,18 +440,45 @@ void coresight_release_path(struct list_head *path)
        path = NULL;
 }
 
+/** coresight_validate_source - make sure a source has the right credentials
+ *  @csdev:    the device structure for a source.
+ *  @function: the function this was called from.
+ *
+ * Assumes the coresight_mutex is held.
+ */
+static int coresight_validate_source(struct coresight_device *csdev,
+                                    const char *function)
+{
+       u32 type, subtype;
+
+       type = csdev->type;
+       subtype = csdev->subtype.source_subtype;
+
+       if (type != CORESIGHT_DEV_TYPE_SOURCE) {
+               dev_err(&csdev->dev, "wrong device type in %s\n", function);
+               return -EINVAL;
+       }
+
+       if (subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_PROC &&
+           subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE) {
+               dev_err(&csdev->dev, "wrong device subtype in %s\n", function);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 int coresight_enable(struct coresight_device *csdev)
 {
-       int ret = 0;
-       int cpu;
+       int cpu, ret = 0;
        struct list_head *path;
 
        mutex_lock(&coresight_mutex);
-       if (csdev->type != CORESIGHT_DEV_TYPE_SOURCE) {
-               ret = -EINVAL;
-               dev_err(&csdev->dev, "wrong device type in %s\n", __func__);
+
+       ret = coresight_validate_source(csdev, __func__);
+       if (ret)
                goto out;
-       }
+
        if (csdev->enable)
                goto out;
 
@@ -461,15 +496,25 @@ int coresight_enable(struct coresight_device *csdev)
        if (ret)
                goto err_source;
 
-       /*
-        * When working from sysFS it is important to keep track
-        * of the paths that were created so that they can be
-        * undone in 'coresight_disable()'.  Since there can only
-        * be a single session per tracer (when working from sysFS)
-        * a per-cpu variable will do just fine.
-        */
-       cpu = source_ops(csdev)->cpu_id(csdev);
-       per_cpu(sysfs_path, cpu) = path;
+       switch (csdev->subtype.source_subtype) {
+       case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
+               /*
+                * When working from sysFS it is important to keep track
+                * of the paths that were created so that they can be
+                * undone in 'coresight_disable()'.  Since there can only
+                * be a single session per tracer (when working from sysFS)
+                * a per-cpu variable will do just fine.
+                */
+               cpu = source_ops(csdev)->cpu_id(csdev);
+               per_cpu(tracer_path, cpu) = path;
+               break;
+       case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
+               stm_path = path;
+               break;
+       default:
+               /* We can't be here */
+               break;
+       }
 
 out:
        mutex_unlock(&coresight_mutex);
@@ -486,23 +531,36 @@ EXPORT_SYMBOL_GPL(coresight_enable);
 
 void coresight_disable(struct coresight_device *csdev)
 {
-       int cpu;
-       struct list_head *path;
+       int cpu, ret;
+       struct list_head *path = NULL;
 
        mutex_lock(&coresight_mutex);
-       if (csdev->type != CORESIGHT_DEV_TYPE_SOURCE) {
-               dev_err(&csdev->dev, "wrong device type in %s\n", __func__);
+
+       ret = coresight_validate_source(csdev, __func__);
+       if (ret)
                goto out;
-       }
+
        if (!csdev->enable)
                goto out;
 
-       cpu = source_ops(csdev)->cpu_id(csdev);
-       path = per_cpu(sysfs_path, cpu);
+       switch (csdev->subtype.source_subtype) {
+       case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
+               cpu = source_ops(csdev)->cpu_id(csdev);
+               path = per_cpu(tracer_path, cpu);
+               per_cpu(tracer_path, cpu) = NULL;
+               break;
+       case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
+               path = stm_path;
+               stm_path = NULL;
+               break;
+       default:
+               /* We can't be here */
+               break;
+       }
+
        coresight_disable_source(csdev);
        coresight_disable_path(path);
        coresight_release_path(path);
-       per_cpu(sysfs_path, cpu) = NULL;
 
 out:
        mutex_unlock(&coresight_mutex);