drm/vc4: Expose performance counters to userspace

The V3D engine has various hardware counters which might be interesting
to userspace performance analysis tools.

Expose new ioctls to create/destroy a performance monitor object and
query the counter values of this perfmance monitor.

Note that a perfomance monitor is given an ID that is only valid on the
file descriptor it has been allocated from. A performance monitor can be
attached to a CL submission and the driver will enable HW counters for
this request and update the performance monitor values at the end of the
job.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180112090926.12538-1-boris.brezillon@free-electrons.com

drivers/gpu/drm/vc4/vc4_perfmon.c

@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Broadcom
+ */
+
+/**
+ * DOC: VC4 V3D performance monitor module
+ *
+ * The V3D block provides 16 hardware counters which can count various events.
+ */
+
+#include "vc4_drv.h"
+#include "vc4_regs.h"
+
+#define VC4_PERFMONID_MIN	1
+#define VC4_PERFMONID_MAX	U32_MAX
+
+void vc4_perfmon_get(struct vc4_perfmon *perfmon)
+{
+	if (perfmon)
+		refcount_inc(&perfmon->refcnt);
+}
+
+void vc4_perfmon_put(struct vc4_perfmon *perfmon)
+{
+	if (perfmon && refcount_dec_and_test(&perfmon->refcnt))
+		kfree(perfmon);
+}
+
+void vc4_perfmon_start(struct vc4_dev *vc4, struct vc4_perfmon *perfmon)
+{
+	unsigned int i;
+	u32 mask;
+
+	if (WARN_ON_ONCE(!perfmon || vc4->active_perfmon))
+		return;
+
+	for (i = 0; i < perfmon->ncounters; i++)
+		V3D_WRITE(V3D_PCTRS(i), perfmon->events[i]);
+
+	mask = GENMASK(perfmon->ncounters - 1, 0);
+	V3D_WRITE(V3D_PCTRC, mask);
+	V3D_WRITE(V3D_PCTRE, V3D_PCTRE_EN | mask);
+	vc4->active_perfmon = perfmon;
+}
+
+void vc4_perfmon_stop(struct vc4_dev *vc4, struct vc4_perfmon *perfmon,
+		      bool capture)
+{
+	unsigned int i;
+
+	if (WARN_ON_ONCE(!vc4->active_perfmon ||
+			 perfmon != vc4->active_perfmon))
+		return;
+
+	if (capture) {
+		for (i = 0; i < perfmon->ncounters; i++)
+			perfmon->counters[i] += V3D_READ(V3D_PCTR(i));
+	}
+
+	V3D_WRITE(V3D_PCTRE, 0);
+	vc4->active_perfmon = NULL;
+}
+
+struct vc4_perfmon *vc4_perfmon_find(struct vc4_file *vc4file, int id)
+{
+	struct vc4_perfmon *perfmon;
+
+	mutex_lock(&vc4file->perfmon.lock);
+	perfmon = idr_find(&vc4file->perfmon.idr, id);
+	vc4_perfmon_get(perfmon);
+	mutex_unlock(&vc4file->perfmon.lock);
+
+	return perfmon;
+}
+
+void vc4_perfmon_open_file(struct vc4_file *vc4file)
+{
+	mutex_init(&vc4file->perfmon.lock);
+	idr_init(&vc4file->perfmon.idr);
+}
+
+static int vc4_perfmon_idr_del(int id, void *elem, void *data)
+{
+	struct vc4_perfmon *perfmon = elem;
+
+	vc4_perfmon_put(perfmon);
+
+	return 0;
+}
+
+void vc4_perfmon_close_file(struct vc4_file *vc4file)
+{
+	mutex_lock(&vc4file->perfmon.lock);
+	idr_for_each(&vc4file->perfmon.idr, vc4_perfmon_idr_del, NULL);
+	idr_destroy(&vc4file->perfmon.idr);
+	mutex_unlock(&vc4file->perfmon.lock);
+}
+
+int vc4_perfmon_create_ioctl(struct drm_device *dev, void *data,
+			     struct drm_file *file_priv)
+{
+	struct vc4_file *vc4file = file_priv->driver_priv;
+	struct drm_vc4_perfmon_create *req = data;
+	struct vc4_perfmon *perfmon;
+	unsigned int i;
+	int ret;
+
+	/* Number of monitored counters cannot exceed HW limits. */
+	if (req->ncounters > DRM_VC4_MAX_PERF_COUNTERS ||
+	    !req->ncounters)
+		return -EINVAL;
+
+	/* Make sure all events are valid. */
+	for (i = 0; i < req->ncounters; i++) {
+		if (req->events[i] >= VC4_PERFCNT_NUM_EVENTS)
+			return -EINVAL;
+	}
+
+	perfmon = kzalloc(sizeof(*perfmon) + (req->ncounters * sizeof(u64)),
+			  GFP_KERNEL);
+	if (!perfmon)
+		return -ENOMEM;
+
+	for (i = 0; i < req->ncounters; i++)
+		perfmon->events[i] = req->events[i];
+
+	perfmon->ncounters = req->ncounters;
+
+	refcount_set(&perfmon->refcnt, 1);
+
+	mutex_lock(&vc4file->perfmon.lock);
+	ret = idr_alloc(&vc4file->perfmon.idr, perfmon, VC4_PERFMONID_MIN,
+			VC4_PERFMONID_MAX, GFP_KERNEL);
+	mutex_unlock(&vc4file->perfmon.lock);
+
+	if (ret < 0) {
+		kfree(perfmon);
+		return ret;
+	}
+
+	req->id = ret;
+	return 0;
+}
+
+int vc4_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
+			      struct drm_file *file_priv)
+{
+	struct vc4_file *vc4file = file_priv->driver_priv;
+	struct drm_vc4_perfmon_destroy *req = data;
+	struct vc4_perfmon *perfmon;
+
+	mutex_lock(&vc4file->perfmon.lock);
+	perfmon = idr_remove(&vc4file->perfmon.idr, req->id);
+	mutex_unlock(&vc4file->perfmon.lock);
+
+	if (!perfmon)
+		return -EINVAL;
+
+	vc4_perfmon_put(perfmon);
+	return 0;
+}
+
+int vc4_perfmon_get_values_ioctl(struct drm_device *dev, void *data,
+				 struct drm_file *file_priv)
+{
+	struct vc4_file *vc4file = file_priv->driver_priv;
+	struct drm_vc4_perfmon_get_values *req = data;
+	struct vc4_perfmon *perfmon;
+	int ret;
+
+	mutex_lock(&vc4file->perfmon.lock);
+	perfmon = idr_find(&vc4file->perfmon.idr, req->id);
+	vc4_perfmon_get(perfmon);
+	mutex_unlock(&vc4file->perfmon.lock);
+
+	if (!perfmon)
+		return -EINVAL;
+
+	if (copy_to_user(u64_to_user_ptr(req->values_ptr), perfmon->counters,
+			 perfmon->ncounters * sizeof(u64)))
+		ret = -EFAULT;
+	else
+		ret = 0;
+
+	vc4_perfmon_put(perfmon);
+	return ret;
+}