uterm: video: add display callbacks

Users might be interested in vertical-blank events so we now allow them to
register event-callbacks on displays. The only event that we currently
pass is a page-flip event that is always sent as reaction to a swap. If
there is no hardware support for such events, we simply throw it from
within the swap() function.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

src/uterm.h

@@ -127,6 +127,14 @@ struct uterm_video_hotplug {
 	int action;
 };
 
+enum uterm_display_action {
+	UTERM_PAGE_FLIP,
+};
+
+struct uterm_display_event {
+	int action;
+};
+
 enum uterm_video_format {
 	UTERM_FORMAT_GREY,
 	UTERM_FORMAT_XRGB32,
@@ -155,6 +163,9 @@ struct uterm_video_blend_req {
 typedef void (*uterm_video_cb) (struct uterm_video *video,
 				struct uterm_video_hotplug *arg,
 				void *data);
+typedef void (*uterm_display_cb) (struct uterm_display *disp,
+				  struct uterm_display_event *arg,
+				  void *data);
 
 /* misc */
 
@@ -203,6 +214,11 @@ void uterm_display_ref(struct uterm_display *disp);
 void uterm_display_unref(struct uterm_display *disp);
 struct uterm_display *uterm_display_next(struct uterm_display *disp);
 
+int uterm_display_register_cb(struct uterm_display *disp, uterm_display_cb cb,
+			      void *data);
+void uterm_display_unregister_cb(struct uterm_display *disp,
+				 uterm_display_cb cb, void *data);
+
 struct uterm_mode *uterm_display_get_modes(struct uterm_display *disp);
 struct uterm_mode *uterm_display_get_current(struct uterm_display *disp);
 struct uterm_mode *uterm_display_get_default(struct uterm_display *disp);

src/uterm_video.c

@@ -270,14 +270,20 @@ int display_new(struct uterm_display **out, const struct display_ops *ops)
 	disp->ref = 1;
 	disp->ops = ops;
 
-	ret = VIDEO_CALL(disp->ops->init, 0, disp);
+	ret = shl_hook_new(&disp->hook);
 	if (ret)
 		goto err_free;
 
+	ret = VIDEO_CALL(disp->ops->init, 0, disp);
+	if (ret)
+		goto err_hook;
+
 	log_info("new display %p", disp);
 	*out = disp;
 	return 0;
 
+err_hook:
+	shl_hook_free(disp->hook);
 err_free:
 	free(disp);
 	return ret;
@@ -307,6 +313,7 @@ void uterm_display_unref(struct uterm_display *disp)
 		mode->next = NULL;
 		uterm_mode_unref(mode);
 	}
+	shl_hook_free(disp->hook);
 	free(disp);
 }
 
@@ -318,6 +325,24 @@ struct uterm_display *uterm_display_next(struct uterm_display *disp)
 	return disp->next;
 }
 
+int uterm_display_register_cb(struct uterm_display *disp, uterm_display_cb cb,
+			      void *data)
+{
+	if (!disp)
+		return -EINVAL;
+
+	return shl_hook_add_cast(disp->hook, cb, data);
+}
+
+void uterm_display_unregister_cb(struct uterm_display *disp,
+				 uterm_display_cb cb, void *data)
+{
+	if (!disp)
+		return;
+
+	shl_hook_rm_cast(disp->hook, cb, data);
+}
+
 struct uterm_mode *uterm_display_get_modes(struct uterm_display *disp)
 {
 	if (!disp)

src/uterm_video.h

@@ -337,6 +337,7 @@ struct uterm_display {
 	struct uterm_display *next;
 	struct uterm_video *video;
 
+	struct shl_hook *hook;
 	struct uterm_mode *modes;
 	struct uterm_mode *default_mode;
 	struct uterm_mode *current_mode;
@@ -352,6 +353,11 @@ struct uterm_display {
 
 int display_new(struct uterm_display **out, const struct display_ops *ops);
 
+#define DISPLAY_CB(disp, act) shl_hook_call((disp)->hook, (disp), \
+		&(struct uterm_display_event){ \
+			.action = (act), \
+		})
+
 static inline bool display_is_conn(const struct uterm_display *disp)
 {
 	return disp->video;

src/uterm_video_drm.c

@@ -979,8 +979,11 @@ static void page_flip_handler(int fd, unsigned int frame, unsigned int sec,
 {
 	struct uterm_display *disp = data;
 
-	disp->flags &= ~DISPLAY_VSYNC;
 	uterm_display_unref(disp);
+	if (disp->flags & DISPLAY_VSYNC) {
+		disp->flags &= ~DISPLAY_VSYNC;
+		DISPLAY_CB(disp, UTERM_PAGE_FLIP);
+	}
 }
 
 static void event(struct ev_fd *fd, int mask, void *data)

src/uterm_video_dumb.c

@@ -742,8 +742,11 @@ static void page_flip_handler(int fd, unsigned int frame, unsigned int sec,
 {
 	struct uterm_display *disp = data;
 
-	disp->flags &= ~DISPLAY_VSYNC;
 	uterm_display_unref(disp);
+	if (disp->flags & DISPLAY_VSYNC) {
+		disp->flags &= ~DISPLAY_VSYNC;
+		DISPLAY_CB(disp, UTERM_PAGE_FLIP);
+	}
 }
 
 static void event(struct ev_fd *fd, int mask, void *data)

src/uterm_video_fbdev.c

@@ -343,8 +343,10 @@ static int display_swap(struct uterm_display *disp)
 	if (!(disp->flags & DISPLAY_ONLINE))
 		return -EINVAL;
 
-	if (!(disp->flags & DISPLAY_DBUF))
+	if (!(disp->flags & DISPLAY_DBUF)) {
+		DISPLAY_CB(disp, UTERM_PAGE_FLIP);
 		return 0;
+	}
 
 	vinfo = &disp->fbdev.vinfo;
 	vinfo->activate = FB_ACTIVATE_VBL;
@@ -362,6 +364,7 @@ static int display_swap(struct uterm_display *disp)
 	}
 
 	disp->fbdev.bufid ^= 1;
+	DISPLAY_CB(disp, UTERM_PAGE_FLIP);
 	return 0;
 }