Add support for vblank events

The kernel will now write data to the DRM fd for various event types if
requested.  Currently, the only supported event is a vblank event: it contains
the vblank count for the event as well as a timestamp from when the event
ocurred.  Since the DRM fd is now pollable, it's easy to integrate into
existing event loops.

1 files changed, 28 insertions, 0 deletions

diff --git a/shared-core/drm.h b/shared-core/drm.h
index d97844f8..089e184a 100644
--- a/shared-core/drm.h
+++ b/shared-core/drm.h
@@ -809,6 +809,34 @@ struct drm_gem_open {
 #define DRM_COMMAND_BASE                0x40
 #define DRM_COMMAND_END                 0xA0
 
+/**
+ * Header for events written back to userspace on the drm fd.  The
+ * type defines the type of event, the length specifies the total
+ * length of the event (including the header), and user_data is
+ * typically a 64 bit value passed with the ioctl that triggered the
+ * event.  A read on the drm fd will always only return complete
+ * events, that is, if for example the read buffer is 100 bytes, and
+ * there are two 64 byte events pending, only one will be returned.
+ *
+ * Event types 0 - 0x7fffffff are generic drm events, 0x80000000 and
+ * up are chipset specific.
+ */
+struct drm_event {
+	uint32_t type;
+	uint32_t length;
+};
+
+#define DRM_EVENT_VBLANK 0x01
+
+struct drm_event_vblank {
+	struct drm_event base;
+	uint64_t user_data;
+	uint32_t tv_sec;
+	uint32_t tv_usec;
+	uint32_t sequence;
+	uint32_t reserved;
+};
+
 /* typedef area */
 #ifndef __KERNEL__
 typedef struct drm_clip_rect drm_clip_rect_t;