V4L/DVB: v4l2: Add new control handling framework

Add a new framework to handle controls which makes life for driver
developers much easier.

Note that this patch moves some of the control support that used to be in
v4l2-common.c to v4l2-ctrls.c. The tables were copied unchanged. The body
of v4l2_ctrl_query_fill() was copied to a new v4l2_ctrl_fill() function
in v4l2-ctrls.c. This new function doesn't use the v4l2_queryctrl
struct anymore, which makes it more general.

The remainder of v4l2-ctrls.c is all new. Highlights include:

- No need to implement VIDIOC_QUERYCTRL, QUERYMENU, S_CTRL, G_CTRL,
  S_EXT_CTRLS, G_EXT_CTRLS or TRY_EXT_CTRLS in either bridge drivers
  or subdevs. New wrapper functions are provided that can just be plugged in.
  Once everything has been converted these wrapper functions can be removed as well.

- When subdevices are added their controls can be automatically merged
  with the bridge driver's controls.

- Most drivers just need to implement s_ctrl to set the controls.
  The framework handles the locking and tries to be as 'atomic' as possible.

- Ready for the subdev device nodes: the same mechanism applies to subdevs
  and their device nodes as well. Sub-device drivers can make controls
  local, preventing them from being merged with bridge drivers.

- Takes care of backwards compatibility handling of VIDIOC_S_CTRL and
  VIDIOC_G_CTRL. Handling of V4L2_CID_PRIVATE_BASE is fully transparent.
  CTRL_CLASS controls are automatically added.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

4 files changed, 471 insertions, 0 deletions

diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
new file mode 100644
index 000000000000..9b7bea928a88
--- /dev/null
+++ b/include/media/v4l2-ctrls.h
@@ -0,0 +1,460 @@
+/*
+    V4L2 controls support header.
+
+    Copyright (C) 2010  Hans Verkuil <hverkuil@xs4all.nl>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _V4L2_CTRLS_H
+#define _V4L2_CTRLS_H
+
+#include <linux/list.h>
+#include <linux/device.h>
+
+/* forward references */
+struct v4l2_ctrl_handler;
+struct v4l2_ctrl;
+struct video_device;
+struct v4l2_subdev;
+
+/** struct v4l2_ctrl_ops - The control operations that the driver has to provide.
+  * @g_volatile_ctrl: Get a new value for this control. Generally only relevant
+  *             for volatile (and usually read-only) controls such as a control
+  *             that returns the current signal strength which changes
+  *             continuously.
+  *             If not set, then the currently cached value will be returned.
+  * @try_ctrl:  Test whether the control's value is valid. Only relevant when
+  *             the usual min/max/step checks are not sufficient.
+  * @s_ctrl:    Actually set the new control value. s_ctrl is compulsory. The
+  *             ctrl->handler->lock is held when these ops are called, so no
+  *             one else can access controls owned by that handler.
+  */
+struct v4l2_ctrl_ops {
+        int (*g_volatile_ctrl)(struct v4l2_ctrl *ctrl);
+        int (*try_ctrl)(struct v4l2_ctrl *ctrl);
+        int (*s_ctrl)(struct v4l2_ctrl *ctrl);
+};
+
+/** struct v4l2_ctrl - The control structure.
+  * @node:      The list node.
+  * @handler:   The handler that owns the control.
+  * @cluster:   Point to start of cluster array.
+  * @ncontrols: Number of controls in cluster array.
+  * @has_new:   Internal flag: set when there is a valid new value.
+  * @done:      Internal flag: set for each processed control.
+  * @is_private: If set, then this control is private to its handler and it
+  *             will not be added to any other handlers. Drivers can set
+  *             this flag.
+  * @is_volatile: If set, then this control is volatile. This means that the
+  *             control's current value cannot be cached and needs to be
+  *             retrieved through the g_volatile_ctrl op. Drivers can set
+  *             this flag.
+  * @ops:       The control ops.
+  * @id:        The control ID.
+  * @name:      The control name.
+  * @type:      The control type.
+  * @minimum:   The control's minimum value.
+  * @maximum:   The control's maximum value.
+  * @default_value: The control's default value.
+  * @step:      The control's step value for non-menu controls.
+  * @menu_skip_mask: The control's skip mask for menu controls. This makes it
+  *             easy to skip menu items that are not valid. If bit X is set,
+  *             then menu item X is skipped. Of course, this only works for
+  *             menus with <= 32 menu items. There are no menus that come
+  *             close to that number, so this is OK. Should we ever need more,
+  *             then this will have to be extended to a u64 or a bit array.
+  * @qmenu:     A const char * array for all menu items. Array entries that are
+  *             empty strings ("") correspond to non-existing menu items (this
+  *             is in addition to the menu_skip_mask above). The last entry
+  *             must be NULL.
+  * @flags:     The control's flags.
+  * @cur:       The control's current value.
+  * @val:       The control's new s32 value.
+  * @val64:     The control's new s64 value.
+  * @string:    The control's new string value.
+  * @priv:      The control's private pointer. For use by the driver. It is
+  *             untouched by the control framework. Note that this pointer is
+  *             not freed when the control is deleted. Should this be needed
+  *             then a new internal bitfield can be added to tell the framework
+  *             to free this pointer.
+  */
+struct v4l2_ctrl {
+        /* Administrative fields */
+        struct list_head node;
+        struct v4l2_ctrl_handler *handler;
+        struct v4l2_ctrl **cluster;
+        unsigned ncontrols;
+        unsigned int has_new:1;
+        unsigned int done:1;
+
+        unsigned int is_private:1;
+        unsigned int is_volatile:1;
+
+        const struct v4l2_ctrl_ops *ops;
+        u32 id;
+        const char *name;
+        enum v4l2_ctrl_type type;
+        s32 minimum, maximum, default_value;
+        union {
+                u32 step;
+                u32 menu_skip_mask;
+        };
+        const char **qmenu;
+        unsigned long flags;
+        union {
+                s32 val;
+                s64 val64;
+                char *string;
+        } cur;
+        union {
+                s32 val;
+                s64 val64;
+                char *string;
+        };
+        void *priv;
+};
+
+/** struct v4l2_ctrl_ref - The control reference.
+  * @node:      List node for the sorted list.
+  * @next:      Single-link list node for the hash.
+  * @ctrl:      The actual control information.
+  *
+  * Each control handler has a list of these refs. The list_head is used to
+  * keep a sorted-by-control-ID list of all controls, while the next pointer
+  * is used to link the control in the hash's bucket.
+  */
+struct v4l2_ctrl_ref {
+        struct list_head node;
+        struct v4l2_ctrl_ref *next;
+        struct v4l2_ctrl *ctrl;
+};
+
+/** struct v4l2_ctrl_handler - The control handler keeps track of all the
+  * controls: both the controls owned by the handler and those inherited
+  * from other handlers.
+  * @lock:      Lock to control access to this handler and its controls.
+  * @ctrls:     The list of controls owned by this handler.
+  * @ctrl_refs: The list of control references.
+  * @cached:    The last found control reference. It is common that the same
+  *             control is needed multiple times, so this is a simple
+  *             optimization.
+  * @buckets:   Buckets for the hashing. Allows for quick control lookup.
+  * @nr_of_buckets: Total number of buckets in the array.
+  * @error:     The error code of the first failed control addition.
+  */
+struct v4l2_ctrl_handler {
+        struct mutex lock;
+        struct list_head ctrls;
+        struct list_head ctrl_refs;
+        struct v4l2_ctrl_ref *cached;
+        struct v4l2_ctrl_ref **buckets;
+        u16 nr_of_buckets;
+        int error;
+};
+
+/** struct v4l2_ctrl_config - Control configuration structure.
+  * @ops:       The control ops.
+  * @id:        The control ID.
+  * @name:      The control name.
+  * @type:      The control type.
+  * @min:       The control's minimum value.
+  * @max:       The control's maximum value.
+  * @step:      The control's step value for non-menu controls.
+  * @def:       The control's default value.
+  * @flags:     The control's flags.
+  * @menu_skip_mask: The control's skip mask for menu controls. This makes it
+  *             easy to skip menu items that are not valid. If bit X is set,
+  *             then menu item X is skipped. Of course, this only works for
+  *             menus with <= 32 menu items. There are no menus that come
+  *             close to that number, so this is OK. Should we ever need more,
+  *             then this will have to be extended to a u64 or a bit array.
+  * @qmenu:     A const char * array for all menu items. Array entries that are
+  *             empty strings ("") correspond to non-existing menu items (this
+  *             is in addition to the menu_skip_mask above). The last entry
+  *             must be NULL.
+  * @is_private: If set, then this control is private to its handler and it
+  *             will not be added to any other handlers.
+  * @is_volatile: If set, then this control is volatile. This means that the
+  *             control's current value cannot be cached and needs to be
+  *             retrieved through the g_volatile_ctrl op.
+  */
+struct v4l2_ctrl_config {
+        const struct v4l2_ctrl_ops *ops;
+        u32 id;
+        const char *name;
+        enum v4l2_ctrl_type type;
+        s32 min;
+        s32 max;
+        u32 step;
+        s32 def;
+        u32 flags;
+        u32 menu_skip_mask;
+        const char **qmenu;
+        unsigned int is_private:1;
+        unsigned int is_volatile:1;
+};
+
+/** v4l2_ctrl_fill() - Fill in the control fields based on the control ID.
+  *
+  * This works for all standard V4L2 controls.
+  * For non-standard controls it will only fill in the given arguments
+  * and @name will be NULL.
+  *
+  * This function will overwrite the contents of @name, @type and @flags.
+  * The contents of @min, @max, @step and @def may be modified depending on
+  * the type.
+  *
+  * Do not use in drivers! It is used internally for backwards compatibility
+  * control handling only. Once all drivers are converted to use the new
+  * control framework this function will no longer be exported.
+  */
+void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
+                    s32 *min, s32 *max, s32 *step, s32 *def, u32 *flags);
+
+
+/** v4l2_ctrl_handler_init() - Initialize the control handler.
+  * @hdl:       The control handler.
+  * @nr_of_controls_hint: A hint of how many controls this handler is
+  *             expected to refer to. This is the total number, so including
+  *             any inherited controls. It doesn't have to be precise, but if
+  *             it is way off, then you either waste memory (too many buckets
+  *             are allocated) or the control lookup becomes slower (not enough
+  *             buckets are allocated, so there are more slow list lookups).
+  *             It will always work, though.
+  *
+  * Returns an error if the buckets could not be allocated. This error will
+  * also be stored in @hdl->error.
+  */
+int v4l2_ctrl_handler_init(struct v4l2_ctrl_handler *hdl,
+                           unsigned nr_of_controls_hint);
+
+/** v4l2_ctrl_handler_free() - Free all controls owned by the handler and free
+  * the control list.
+  * @hdl:       The control handler.
+  *
+  * Does nothing if @hdl == NULL.
+  */
+void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl);
+
+/** v4l2_ctrl_handler_setup() - Call the s_ctrl op for all controls belonging
+  * to the handler to initialize the hardware to the current control values.
+  * @hdl:       The control handler.
+  *
+  * Button controls will be skipped, as are read-only controls.
+  *
+  * If @hdl == NULL, then this just returns 0.
+  */
+int v4l2_ctrl_handler_setup(struct v4l2_ctrl_handler *hdl);
+
+/** v4l2_ctrl_handler_log_status() - Log all controls owned by the handler.
+  * @hdl:       The control handler.
+  * @prefix:    The prefix to use when logging the control values. If the
+  *             prefix does not end with a space, then ": " will be added
+  *             after the prefix. If @prefix == NULL, then no prefix will be
+  *             used.
+  *
+  * For use with VIDIOC_LOG_STATUS.
+  *
+  * Does nothing if @hdl == NULL.
+  */
+void v4l2_ctrl_handler_log_status(struct v4l2_ctrl_handler *hdl,
+                                  const char *prefix);
+
+/** v4l2_ctrl_new_custom() - Allocate and initialize a new custom V4L2
+  * control.
+  * @hdl:       The control handler.
+  * @cfg:       The control's configuration data.
+  * @priv:      The control's driver-specific private data.
+  *
+  * If the &v4l2_ctrl struct could not be allocated then NULL is returned
+  * and @hdl->error is set to the error code (if it wasn't set already).
+  */
+struct v4l2_ctrl *v4l2_ctrl_new_custom(struct v4l2_ctrl_handler *hdl,
+                        const struct v4l2_ctrl_config *cfg, void *priv);
+
+/** v4l2_ctrl_new_std() - Allocate and initialize a new standard V4L2 non-menu control.
+  * @hdl:       The control handler.
+  * @ops:       The control ops.
+  * @id:        The control ID.
+  * @min:       The control's minimum value.
+  * @max:       The control's maximum value.
+  * @step:      The control's step value
+  * @def:       The control's default value.
+  *
+  * If the &v4l2_ctrl struct could not be allocated, or the control
+  * ID is not known, then NULL is returned and @hdl->error is set to the
+  * appropriate error code (if it wasn't set already).
+  *
+  * If @id refers to a menu control, then this function will return NULL.
+  *
+  * Use v4l2_ctrl_new_std_menu() when adding menu controls.
+  */
+struct v4l2_ctrl *v4l2_ctrl_new_std(struct v4l2_ctrl_handler *hdl,
+                        const struct v4l2_ctrl_ops *ops,
+                        u32 id, s32 min, s32 max, u32 step, s32 def);
+
+/** v4l2_ctrl_new_std_menu() - Allocate and initialize a new standard V4L2 menu control.
+  * @hdl:       The control handler.
+  * @ops:       The control ops.
+  * @id:        The control ID.
+  * @max:       The control's maximum value.
+  * @mask:      The control's skip mask for menu controls. This makes it
+  *             easy to skip menu items that are not valid. If bit X is set,
+  *             then menu item X is skipped. Of course, this only works for
+  *             menus with <= 32 menu items. There are no menus that come
+  *             close to that number, so this is OK. Should we ever need more,
+  *             then this will have to be extended to a u64 or a bit array.
+  * @def:       The control's default value.
+  *
+  * Same as v4l2_ctrl_new_std(), but @min is set to 0 and the @mask value
+  * determines which menu items are to be skipped.
+  *
+  * If @id refers to a non-menu control, then this function will return NULL.
+  */
+struct v4l2_ctrl *v4l2_ctrl_new_std_menu(struct v4l2_ctrl_handler *hdl,
+                        const struct v4l2_ctrl_ops *ops,
+                        u32 id, s32 max, s32 mask, s32 def);
+
+/** v4l2_ctrl_add_ctrl() - Add a control from another handler to this handler.
+  * @hdl:       The control handler.
+  * @ctrl:      The control to add.
+  *
+  * It will return NULL if it was unable to add the control reference.
+  * If the control already belonged to the handler, then it will do
+  * nothing and just return @ctrl.
+  */
+struct v4l2_ctrl *v4l2_ctrl_add_ctrl(struct v4l2_ctrl_handler *hdl,
+                                          struct v4l2_ctrl *ctrl);
+
+/** v4l2_ctrl_add_handler() - Add all controls from handler @add to
+  * handler @hdl.
+  * @hdl:       The control handler.
+  * @add:       The control handler whose controls you want to add to
+  *             the @hdl control handler.
+  *
+  * Does nothing if either of the two is a NULL pointer.
+  * In case of an error @hdl->error will be set to the error code (if it
+  * wasn't set already).
+  */
+int v4l2_ctrl_add_handler(struct v4l2_ctrl_handler *hdl,
+                          struct v4l2_ctrl_handler *add);
+
+
+/** v4l2_ctrl_cluster() - Mark all controls in the cluster as belonging to that cluster.
+  * @ncontrols: The number of controls in this cluster.
+  * @controls:  The cluster control array of size @ncontrols.
+  */
+void v4l2_ctrl_cluster(unsigned ncontrols, struct v4l2_ctrl **controls);
+
+
+/** v4l2_ctrl_find() - Find a control with the given ID.
+  * @hdl:       The control handler.
+  * @id:        The control ID to find.
+  *
+  * If @hdl == NULL this will return NULL as well. Will lock the handler so
+  * do not use from inside &v4l2_ctrl_ops.
+  */
+struct v4l2_ctrl *v4l2_ctrl_find(struct v4l2_ctrl_handler *hdl, u32 id);
+
+/** v4l2_ctrl_activate() - Make the control active or inactive.
+  * @ctrl:      The control to (de)activate.
+  * @active:    True if the control should become active.
+  *
+  * This sets or clears the V4L2_CTRL_FLAG_INACTIVE flag atomically.
+  * Does nothing if @ctrl == NULL.
+  * This will usually be called from within the s_ctrl op.
+  *
+  * This function can be called regardless of whether the control handler
+  * is locked or not.
+  */
+void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool active);
+
+/** v4l2_ctrl_grab() - Mark the control as grabbed or not grabbed.
+  * @ctrl:      The control to (de)activate.
+  * @grabbed:   True if the control should become grabbed.
+  *
+  * This sets or clears the V4L2_CTRL_FLAG_GRABBED flag atomically.
+  * Does nothing if @ctrl == NULL.
+  * This will usually be called when starting or stopping streaming in the
+  * driver.
+  *
+  * This function can be called regardless of whether the control handler
+  * is locked or not.
+  */
+void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);
+
+/** v4l2_ctrl_lock() - Helper function to lock the handler
+  * associated with the control.
+  * @ctrl:      The control to lock.
+  */
+static inline void v4l2_ctrl_lock(struct v4l2_ctrl *ctrl)
+{
+        mutex_lock(&ctrl->handler->lock);
+}
+
+/** v4l2_ctrl_lock() - Helper function to unlock the handler
+  * associated with the control.
+  * @ctrl:      The control to unlock.
+  */
+static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl)
+{
+        mutex_unlock(&ctrl->handler->lock);
+}
+
+/** v4l2_ctrl_g_ctrl() - Helper function to get the control's value from within a driver.
+  * @ctrl:      The control.
+  *
+  * This returns the control's value safely by going through the control
+  * framework. This function will lock the control's handler, so it cannot be
+  * used from within the &v4l2_ctrl_ops functions.
+  *
+  * This function is for integer type controls only.
+  */
+s32 v4l2_ctrl_g_ctrl(struct v4l2_ctrl *ctrl);
+
+/** v4l2_ctrl_s_ctrl() - Helper function to set the control's value from within a driver.
+  * @ctrl:      The control.
+  * @val:       The new value.
+  *
+  * This set the control's new value safely by going through the control
+  * framework. This function will lock the control's handler, so it cannot be
+  * used from within the &v4l2_ctrl_ops functions.
+  *
+  * This function is for integer type controls only.
+  */
+int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val);
+
+
+/* Helpers for ioctl_ops. If hdl == NULL then they will all return -EINVAL. */
+int v4l2_queryctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_queryctrl *qc);
+int v4l2_querymenu(struct v4l2_ctrl_handler *hdl, struct v4l2_querymenu *qm);
+int v4l2_g_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *ctrl);
+int v4l2_s_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *ctrl);
+int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
+int v4l2_try_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
+int v4l2_s_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *c);
+
+/* Helpers for subdevices. If the associated ctrl_handler == NULL then they
+   will all return -EINVAL. */
+int v4l2_subdev_queryctrl(struct v4l2_subdev *sd, struct v4l2_queryctrl *qc);
+int v4l2_subdev_querymenu(struct v4l2_subdev *sd, struct v4l2_querymenu *qm);
+int v4l2_subdev_g_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
+int v4l2_subdev_try_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
+int v4l2_subdev_s_ext_ctrls(struct v4l2_subdev *sd, struct v4l2_ext_controls *cs);
+int v4l2_subdev_g_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl);
+int v4l2_subdev_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl);
+
+#endif
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index bebe44b03e0f..1efcacbed01a 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -27,6 +27,7 @@
 struct v4l2_ioctl_callbacks;
 struct video_device;
 struct v4l2_device;
+struct v4l2_ctrl_handler;
 
 /* Flag to mark the video_device struct as registered.
    Drivers can clear this flag if they want to block all future
@@ -67,6 +68,9 @@ struct video_device
         struct device *parent;          /* device parent */
         struct v4l2_device *v4l2_dev;   /* v4l2_device parent */
 
+        /* Control handler associated with this device node. May be NULL. */
+        struct v4l2_ctrl_handler *ctrl_handler;
+
         /* device info */
         char name[32];
         int vfl_type;
diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index 5d5d550e63ad..8bcbd7a0271c 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -32,6 +32,8 @@
 
 #define V4L2_DEVICE_NAME_SIZE (20 + 16)
 
+struct v4l2_ctrl_handler;
+
 struct v4l2_device {
         /* dev->driver_data points to this struct.
            Note: dev might be NULL if there is no parent device
@@ -47,6 +49,8 @@ struct v4l2_device {
         /* notify callback called by some sub-devices. */
         void (*notify)(struct v4l2_subdev *sd,
                         unsigned int notification, void *arg);
+        /* The control handler. May be NULL. */
+        struct v4l2_ctrl_handler *ctrl_handler;
 };
 
 /* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev.
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 08880dd15d2f..4a97d7341a94 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -35,6 +35,7 @@
 #define V4L2_SUBDEV_IR_TX_FIFO_SERVICE_REQ      0x00000001
 
 struct v4l2_device;
+struct v4l2_ctrl_handler;
 struct v4l2_subdev;
 struct tuner_setup;
 
@@ -434,6 +435,8 @@ struct v4l2_subdev {
         u32 flags;
         struct v4l2_device *v4l2_dev;
         const struct v4l2_subdev_ops *ops;
+        /* The control handler of this subdev. May be NULL. */
+        struct v4l2_ctrl_handler *ctrl_handler;
         /* name must be unique */
         char name[V4L2_SUBDEV_NAME_SIZE];
         /* can be used to group similar subdevs, value is driver-specific */