[PATCH v2 2/6] media: subdev: add active state to struct v4l2_subdev

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

Add a new 'active_state' field to struct v4l2_subdev to which we can
store the active state of a subdev. This will place the subdev
configuration into a known place, allowing us to use the state directly
from the v4l2 framework, thus simplifying the drivers.

Also add functions v4l2_subdev_init_finalize() and
v4l2_subdev_cleanup(), which will allocate and free the active state.
The functions are named in a generic way so that they can be also used
for other subdev initialization work.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 21 ++++++++++
 include/media/v4l2-subdev.h           | 58 +++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index fe49c86a9b02..de160140d63b 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -943,3 +943,24 @@ void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
 	v4l2_subdev_notify(sd, V4L2_DEVICE_NOTIFY_EVENT, (void *)ev);
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_notify_event);
+
+int v4l2_subdev_init_finalize(struct v4l2_subdev *sd)
+{
+	struct v4l2_subdev_state *state;
+
+	state = __v4l2_subdev_state_alloc(sd);
+	if (IS_ERR(state))
+		return PTR_ERR(state);
+
+	sd->active_state = state;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_init_finalize);
+
+void v4l2_subdev_cleanup(struct v4l2_subdev *sd)
+{
+	__v4l2_subdev_state_free(sd->active_state);
+	sd->active_state = NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_cleanup);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index e52bf508c75b..eddf72768e10 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -645,6 +645,9 @@ struct v4l2_subdev_ir_ops {
  * This structure only needs to be passed to the pad op if the 'which' field
  * of the main argument is set to %V4L2_SUBDEV_FORMAT_TRY. For
  * %V4L2_SUBDEV_FORMAT_ACTIVE it is safe to pass %NULL.
+ *
+ * Note: This struct is also used in active state, and the try_ prefix is
+ * historical and to be removed.
  */
 struct v4l2_subdev_pad_config {
 	struct v4l2_mbus_framefmt try_fmt;
@@ -898,6 +901,9 @@ struct v4l2_subdev_platform_data {
  * @subdev_notifier: A sub-device notifier implicitly registered for the sub-
  *		     device using v4l2_async_register_subdev_sensor().
  * @pdata: common part of subdevice platform data
+ * @active_state: Active state for the subdev (NULL for subdevs tracking the
+ *		  state internally). Initialized by calling
+ *		  v4l2_subdev_init_finalize().
  *
  * Each instance of a subdev driver should create this struct, either
  * stand-alone or embedded in a larger struct.
@@ -929,6 +935,19 @@ struct v4l2_subdev {
 	struct v4l2_async_notifier *notifier;
 	struct v4l2_async_notifier *subdev_notifier;
 	struct v4l2_subdev_platform_data *pdata;
+
+	/*
+	 * The fields below are private, and should only be accessed via
+	 * appropriate functions.
+	 */
+
+	/*
+	 * TODO: active_state should most likely be changed from a pointer to an
+	 * embedded field. For the time being it's kept as a pointer to more
+	 * easily catch uses of active_state in the cases where the driver
+	 * doesn't support it.
+	 */
+	struct v4l2_subdev_state *active_state;
 };
 
 
@@ -1217,4 +1236,43 @@ extern const struct v4l2_subdev_ops v4l2_subdev_call_wrappers;
 void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
 			      const struct v4l2_event *ev);
 
+/**
+ * v4l2_subdev_init_finalize() - Finalizes the initialization of the subdevice
+ * @sd: The subdev
+ *
+ * This function finalizes the initialization of the subdev, including
+ * allocation of the active state for the subdev.
+ *
+ * This function must be called by the subdev drivers that use the centralized
+ * active state, after the subdev struct has been initialized and
+ * media_entity_pads_init() has been called, but before registering the
+ * subdev.
+ *
+ * The user must call v4l2_subdev_cleanup() when the subdev is being removed.
+ */
+int v4l2_subdev_init_finalize(struct v4l2_subdev *sd);
+
+/**
+ * v4l2_subdev_cleanup() - Releases the resources needed by the subdevice
+ * @sd: The subdevice
+ *
+ * This function will release the resources allocated in
+ * v4l2_subdev_init_finalize.
+ */
+void v4l2_subdev_cleanup(struct v4l2_subdev *sd);
+
+/**
+ * v4l2_subdev_get_active_state() - Returns the active subdev state for
+ *				    subdevice
+ * @sd: The subdevice
+ *
+ * Returns the active state for the subdevice, or NULL if the subdev does not
+ * support active state.
+ */
+static inline struct v4l2_subdev_state *
+v4l2_subdev_get_active_state(struct v4l2_subdev *sd)
+{
+	return sd->active_state;
+}
+
 #endif
-- 
2.25.1