[PATCH v4 09/13] drm/panfrost: Add debugfs knob for manually triggering a GPU reset

["Adrián Larumbe" <adrian.larumbe@collabora.com>]

This will be of great help when testing potential races between the GPU
reset sequence and other parts of the code accessing HW registers.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_device.c | 41 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_device.h |  3 +++
 drivers/gpu/drm/panfrost/panfrost_drv.c    |  1 +
 3 files changed, 45 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index a51f1ef8563c..c0334b72c70b 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -2,6 +2,7 @@
 /* Copyright 2018 Marty E. Plummer <hanetzer@startmail.com> */
 /* Copyright 2019 Linaro, Ltd, Rob Herring <robh@kernel.org> */
 
+#include <linux/debugfs.h>
 #include <linux/clk.h>
 #include <linux/reset.h>
 #include <linux/platform_device.h>
@@ -629,3 +630,43 @@ void panfrost_device_reset(struct panfrost_device *pfdev, bool enable_job_int)
 	if (!panfrost_device_started(pfdev) && !ret)
 		pfdev->gpu_started = true;
 }
+
+#ifdef CONFIG_DEBUG_FS
+static int reset_get(void *data, u64 *val)
+{
+	struct panfrost_device *pfdev =
+		container_of(data, struct panfrost_device, base);
+
+	*val = atomic_read(&pfdev->reset.pending);
+	return 0;
+}
+
+static int reset_set(void *data, u64 val)
+{
+	struct panfrost_device *pfdev =
+		container_of(data, struct panfrost_device, base);
+	int ret;
+
+	ret = pm_runtime_get_if_in_use(pfdev->base.dev);
+
+	if (ret > 0) {
+		panfrost_device_schedule_reset(pfdev);
+		ret = wait_event_interruptible_timeout(pfdev->reset.wait,
+						       !atomic_read(&pfdev->reset.pending),
+						       msecs_to_jiffies(60));
+		pm_runtime_put(pfdev->base.dev);
+	}
+
+	return (ret > 0) ? 0 : -ETIMEDOUT;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(panfrost_reset_debugfs_fops,
+			 reset_get, reset_set,
+			 "0x%08llx\n");
+
+void panfrost_reset_debugfs_init(struct drm_minor *minor)
+{
+	debugfs_create_file("reset", 0600, minor->debugfs_root,
+			    minor->dev, &panfrost_reset_debugfs_fops);
+}
+#endif // CONFIG_DEBUG_FS
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index f0acfc634cd4..f96ba50dfa91 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -352,4 +352,7 @@ panfrost_device_started(struct panfrost_device *pfdev)
 	return pfdev->gpu_started;
 }
 
+#ifdef CONFIG_DEBUG_FS
+void panfrost_reset_debugfs_init(struct drm_minor *minor);
+#endif // CONFIG_DEBUG_FS
 #endif
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index 27f4c4b217f5..fac5be20ad60 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -916,6 +916,7 @@ static void panfrost_debugfs_init(struct drm_minor *minor)
 {
 	panthor_gems_debugfs_init(minor);
 	panfrost_sched_debugfs_init(minor);
+	panfrost_reset_debugfs_init(minor);
 }
 #endif
 

-- 
2.55.0