[media] v4l: subdev: Events support

Provide v4l2_subdevs with v4l2_event support. Subdev drivers only need very
little to support events.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: David Cohen <dacohen@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 105 insertions, 1 deletions

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 1feecfc59c3d..eb8479565dc4 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -350,6 +350,24 @@ VIDIOC_TRY_EXT_CTRLS
         controls can be also be accessed through one (or several) V4L2 device
         nodes.
 
+VIDIOC_DQEVENT
+VIDIOC_SUBSCRIBE_EVENT
+VIDIOC_UNSUBSCRIBE_EVENT
+
+        The events ioctls are identical to the ones defined in V4L2. They
+        behave identically, with the only exception that they deal only with
+        events generated by the sub-device. Depending on the driver, those
+        events can also be reported by one (or several) V4L2 device nodes.
+
+        Sub-device drivers that want to use events need to set the
+        V4L2_SUBDEV_USES_EVENTS v4l2_subdev::flags and initialize
+        v4l2_subdev::nevents to events queue depth before registering the
+        sub-device. After registration events can be queued as usual on the
+        v4l2_subdev::devnode device node.
+
+        To properly support events, the poll() file operation is also
+        implemented.
+
 
 I2C sub-device drivers
 ----------------------
diff --git a/drivers/media/video/v4l2-subdev.c b/drivers/media/video/v4l2-subdev.c
index da10430051c0..0c67f5a278fb 100644
--- a/drivers/media/video/v4l2-subdev.c
+++ b/drivers/media/video/v4l2-subdev.c
@@ -20,21 +20,66 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include <linux/types.h>
 #include <linux/ioctl.h>
+#include <linux/slab.h>
+#include <linux/types.h>
 #include <linux/videodev2.h>
 
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
 
 static int subdev_open(struct file *file)
 {
+        struct video_device *vdev = video_devdata(file);
+        struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
+        struct v4l2_fh *vfh;
+        int ret;
+
+        if (sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS) {
+                vfh = kzalloc(sizeof(*vfh), GFP_KERNEL);
+                if (vfh == NULL)
+                        return -ENOMEM;
+
+                ret = v4l2_fh_init(vfh, vdev);
+                if (ret)
+                        goto err;
+
+                ret = v4l2_event_init(vfh);
+                if (ret)
+                        goto err;
+
+                ret = v4l2_event_alloc(vfh, sd->nevents);
+                if (ret)
+                        goto err;
+
+                v4l2_fh_add(vfh);
+                file->private_data = vfh;
+        }
+
         return 0;
+
+err:
+        if (vfh != NULL) {
+                v4l2_fh_exit(vfh);
+                kfree(vfh);
+        }
+
+        return ret;
 }
 
 static int subdev_close(struct file *file)
 {
+        struct v4l2_fh *vfh = file->private_data;
+
+        if (vfh != NULL) {
+                v4l2_fh_del(vfh);
+                v4l2_fh_exit(vfh);
+                kfree(vfh);
+        }
+
         return 0;
 }
 
@@ -42,6 +87,7 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 {
         struct video_device *vdev = video_devdata(file);
         struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
+        struct v4l2_fh *fh = file->private_data;
 
         switch (cmd) {
         case VIDIOC_QUERYCTRL:
@@ -65,6 +111,18 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
         case VIDIOC_TRY_EXT_CTRLS:
                 return v4l2_subdev_try_ext_ctrls(sd, arg);
 
+        case VIDIOC_DQEVENT:
+                if (!(sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS))
+                        return -ENOIOCTLCMD;
+
+                return v4l2_event_dequeue(fh, arg, file->f_flags & O_NONBLOCK);
+
+        case VIDIOC_SUBSCRIBE_EVENT:
+                return v4l2_subdev_call(sd, core, subscribe_event, fh, arg);
+
+        case VIDIOC_UNSUBSCRIBE_EVENT:
+                return v4l2_subdev_call(sd, core, unsubscribe_event, fh, arg);
+
         default:
                 return -ENOIOCTLCMD;
         }
@@ -78,11 +136,29 @@ static long subdev_ioctl(struct file *file, unsigned int cmd,
         return video_usercopy(file, cmd, arg, subdev_do_ioctl);
 }
 
+static unsigned int subdev_poll(struct file *file, poll_table *wait)
+{
+        struct video_device *vdev = video_devdata(file);
+        struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
+        struct v4l2_fh *fh = file->private_data;
+
+        if (!(sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS))
+                return POLLERR;
+
+        poll_wait(file, &fh->events->wait, wait);
+
+        if (v4l2_event_pending(fh))
+                return POLLPRI;
+
+        return 0;
+}
+
 const struct v4l2_file_operations v4l2_subdev_fops = {
         .owner = THIS_MODULE,
         .open = subdev_open,
         .unlocked_ioctl = subdev_ioctl,
         .release = subdev_close,
+        .poll = subdev_poll,
 };
 
 void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 3276065022ef..0f9937be53d2 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -37,6 +37,8 @@
 
 struct v4l2_device;
 struct v4l2_ctrl_handler;
+struct v4l2_event_subscription;
+struct v4l2_fh;
 struct v4l2_subdev;
 struct tuner_setup;
 
@@ -161,6 +163,10 @@ struct v4l2_subdev_core_ops {
         int (*s_power)(struct v4l2_subdev *sd, int on);
         int (*interrupt_service_routine)(struct v4l2_subdev *sd,
                                                 u32 status, bool *handled);
+        int (*subscribe_event)(struct v4l2_subdev *sd, struct v4l2_fh *fh,
+                               struct v4l2_event_subscription *sub);
+        int (*unsubscribe_event)(struct v4l2_subdev *sd, struct v4l2_fh *fh,
+                                 struct v4l2_event_subscription *sub);
 };
 
 /* s_mode: switch the tuner to a specific tuner mode. Replacement of s_radio.
@@ -437,6 +443,8 @@ struct v4l2_subdev_internal_ops {
 #define V4L2_SUBDEV_FL_IS_SPI                   (1U << 1)
 /* Set this flag if this subdev needs a device node. */
 #define V4L2_SUBDEV_FL_HAS_DEVNODE              (1U << 2)
+/* Set this flag if this subdev generates events. */
+#define V4L2_SUBDEV_FL_HAS_EVENTS               (1U << 3)
 
 /* Each instance of a subdev driver should create this struct, either
    stand-alone or embedded in a larger struct.
@@ -460,6 +468,8 @@ struct v4l2_subdev {
         void *host_priv;
         /* subdev device node */
         struct video_device devnode;
+        /* number of events to be allocated on open */
+        unsigned int nevents;
 };
 
 #define vdev_to_v4l2_subdev(vdev) \