[PATCH v6 4/5] drm/mgag200: Add drm_panic support

[Jocelyn Falempe <jfalempe@redhat.com>]

Add support for the drm_panic module, which displays a message to
the screen when a kernel panic occurs.

v5:
 * Also check that the plane is visible and primary. (Thomas Zimmermann)

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
---
 drivers/gpu/drm/mgag200/mgag200_drv.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c
index 2fb18b782b05..c79f3d9ee39a 100644
--- a/drivers/gpu/drm/mgag200/mgag200_drv.c
+++ b/drivers/gpu/drm/mgag200/mgag200_drv.c
@@ -13,10 +13,12 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_fbdev_generic.h>
+#include <drm/drm_framebuffer.h>
 #include <drm/drm_file.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_module.h>
+#include <drm/drm_panic.h>
 #include <drm/drm_pciids.h>
 
 #include "mgag200_drv.h"
@@ -84,6 +86,28 @@ resource_size_t mgag200_probe_vram(void __iomem *mem, resource_size_t size)
 	return offset - 65536;
 }
 
+static int mgag200_get_scanout_buffer(struct drm_device *dev,
+				      struct drm_scanout_buffer *sb)
+{
+	struct drm_plane *plane;
+	struct mga_device *mdev = to_mga_device(dev);
+	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(mdev->vram);
+
+	/* find the primary and visible plane */
+	drm_for_each_plane(plane, dev) {
+		if (!plane->state || !plane->state->visible || !plane->state->fb ||
+		    plane->type != DRM_PLANE_TYPE_PRIMARY)
+			continue;
+		sb->format = plane->state->fb->format;
+		sb->width = plane->state->fb->width;
+		sb->height = plane->state->fb->height;
+		sb->pitch = plane->state->fb->pitches[0];
+		sb->map = map;
+		return 0;
+	}
+	return -ENODEV;
+}
+
 /*
  * DRM driver
  */
@@ -99,6 +123,7 @@ static const struct drm_driver mgag200_driver = {
 	.major = DRIVER_MAJOR,
 	.minor = DRIVER_MINOR,
 	.patchlevel = DRIVER_PATCHLEVEL,
+	.get_scanout_buffer = mgag200_get_scanout_buffer,
 	DRM_GEM_SHMEM_DRIVER_OPS,
 };
 
-- 
2.42.0