Subject: [PATCH 01/19] OMAP4: DSS: add generic notifier mechanism

A callback can be registered by the dssdev client in order to be
notified of resolution changes, for example an external monitor
that is hot-plugged.

Multiple clients can now register for notification from one
dssdev, and the notification mechanism can be extended in the
future to add other events.

This is a port of Rob Clark's <rob@ti.com> original patch.

Signed-off-by: Sebastien Jan <s-jan@ti.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

3 files changed, 65 insertions, 0 deletions

diff --git a/drivers/video/omap2/dss/core.c b/drivers/video/omap2/dss/core.c
index 3da426719dd..7a213c8dbbb 100644
--- a/drivers/video/omap2/dss/core.c
+++ b/drivers/video/omap2/dss/core.c
@@ -492,6 +492,9 @@ static int omap_dss_register_device(struct omap_dss_device *dssdev)
 	dssdev->dev.parent = &dss_bus;
 	dssdev->dev.release = omap_dss_dev_release;
 	dev_set_name(&dssdev->dev, "display%d", dev_num++);
+
+	BLOCKING_INIT_NOTIFIER_HEAD(&dssdev->notifier);
+
 	return device_register(&dssdev->dev);
 }
 
diff --git a/drivers/video/omap2/dss/display.c b/drivers/video/omap2/dss/display.c
index c2dfc8c5005..9d0c7e4cbf1 100644
--- a/drivers/video/omap2/dss/display.c
+++ b/drivers/video/omap2/dss/display.c
@@ -26,6 +26,7 @@
 #include <linux/module.h>
 #include <linux/jiffies.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
 
 #include <video/omapdss.h>
 #include "dss.h"
@@ -628,3 +629,50 @@ void omap_dss_stop_device(struct omap_dss_device *dssdev)
 }
 EXPORT_SYMBOL(omap_dss_stop_device);
 
+/* since omap_dss_update_size can be called in irq context, schedule work from
+ * work-queue to deliver notification to client..
+ */
+struct notify_work {
+	struct work_struct work;
+	struct omap_dss_device *dssdev;
+	enum omap_dss_event evt;
+};
+
+static void notify_worker(struct work_struct *work)
+{
+	struct notify_work *nw =
+		container_of(work, struct notify_work, work);
+	struct omap_dss_device *dssdev = nw->dssdev;
+	blocking_notifier_call_chain(&dssdev->notifier, nw->evt, dssdev);
+	kfree(work);
+}
+
+/**
+ * Called by lower level driver to notify about a change in resolution, etc.
+ */
+void omap_dss_notify(struct omap_dss_device *dssdev, enum omap_dss_event evt)
+{
+	struct notify_work *nw =
+			kmalloc(sizeof(struct notify_work), GFP_KERNEL);
+	if (nw) {
+		INIT_WORK(&nw->work, notify_worker);
+		nw->dssdev = dssdev;
+		nw->evt = evt;
+		schedule_work(&nw->work);
+	}
+}
+EXPORT_SYMBOL(omap_dss_notify);
+
+void omap_dss_add_notify(struct omap_dss_device *dssdev,
+		struct notifier_block *nb)
+{
+	blocking_notifier_chain_register(&dssdev->notifier, nb);
+}
+EXPORT_SYMBOL(omap_dss_add_notify);
+
+void omap_dss_remove_notify(struct omap_dss_device *dssdev,
+		struct notifier_block *nb)
+{
+	blocking_notifier_chain_unregister(&dssdev->notifier, nb);
+}
+EXPORT_SYMBOL(omap_dss_remove_notify);
diff --git a/include/video/omapdss.h b/include/video/omapdss.h
index 892b97f8e15..2a94d66db90 100644
--- a/include/video/omapdss.h
+++ b/include/video/omapdss.h
@@ -21,6 +21,7 @@
 #include <linux/list.h>
 #include <linux/kobject.h>
 #include <linux/device.h>
+#include <linux/notifier.h>
 #include <linux/platform_device.h>
 #include <asm/atomic.h>
 
@@ -506,6 +507,7 @@ struct omap_dss_device {
 	struct omap_overlay_manager *manager;
 
 	enum omap_dss_display_state state;
+	struct blocking_notifier_head notifier;
 
 	/* platform specific  */
 	int (*platform_enable)(struct omap_dss_device *dssdev);
@@ -578,6 +580,18 @@ struct omap_dss_device *omap_dss_find_device(void *data,
 int omap_dss_start_device(struct omap_dss_device *dssdev);
 void omap_dss_stop_device(struct omap_dss_device *dssdev);
 
+/* the event id of the event that occurred is passed in as the second arg
+ * to the notifier function, and the dssdev is passed as the third.
+ */
+enum omap_dss_event {
+	OMAP_DSS_SIZE_CHANGE
+	/* possibly add additional events, like hot-plug connect/disconnect */
+};
+
+void omap_dss_notify(struct omap_dss_device *dssdev, enum omap_dss_event evt);
+void omap_dss_add_notify(struct omap_dss_device *dssdev, struct notifier_block *nb);
+void omap_dss_remove_notify(struct omap_dss_device *dssdev, struct notifier_block *nb);
+
 int omap_dss_get_num_overlay_managers(void);
 struct omap_overlay_manager *omap_dss_get_overlay_manager(int num);