[PATCH v5] media: v4l2-ctrl: add a helper function to add standard control with driver specific menu

[Prabhakar <prabhakar.csengg@gmail.com>]

From: Lad, Prabhakar <prabhakar.lad@ti.com>

Add helper function v4l2_ctrl_new_std_menu_items(), which adds
a standard menu control, with driver specific menu.

Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Rob Landley <rob@landley.net>
---
 Changes for v5:
 1: Fixed some grammatical issues pointed by Hans.

 Changes for v4:
 1: Rather then adding a function to modify the menu, added a helper
   function, that creates a new standard control with user specific
   menu.

 Changes for v3:
 1: Fixed style/grammer issues as pointed by Hans.
   Thanks Hans for providing the description.

 Changes for v2:
 1: Fixed review comments from Hans, to have return type as
   void, add WARN_ON() for fail conditions, allow this fucntion
   to modify the menu of custom controls.

 Documentation/video4linux/v4l2-controls.txt |   24 +++++++++++++++++++++
 drivers/media/v4l2-core/v4l2-ctrls.c        |   30 +++++++++++++++++++++++++++
 include/media/v4l2-ctrls.h                  |   23 ++++++++++++++++++++
 3 files changed, 77 insertions(+), 0 deletions(-)

diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt
index 43da22b..b0cb0b8 100644
--- a/Documentation/video4linux/v4l2-controls.txt
+++ b/Documentation/video4linux/v4l2-controls.txt
@@ -136,11 +136,25 @@ Or alternatively for integer menu controls, by calling v4l2_ctrl_new_int_menu:
 			const struct v4l2_ctrl_ops *ops,
 			u32 id, s32 max, s32 def, const s64 *qmenu_int);
 
+Standard menu controls with a driver specific menu are added by calling
+v4l2_ctrl_new_std_menu_items:
+
+	struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(
+		struct v4l2_ctrl_handler *hdl,
+		const struct v4l2_ctrl_ops *ops, u32 id, s32 max,
+		s32 skip_mask, s32 def, const char * const *qmenu);
+
 These functions are typically called right after the v4l2_ctrl_handler_init:
 
 	static const s64 exp_bias_qmenu[] = {
 	       -2, -1, 0, 1, 2
 	};
+	static const char * const test_pattern[] = {
+		"Disabled",
+		"Vertical Bars",
+		"Solid Black",
+		"Solid White",
+	};
 
 	v4l2_ctrl_handler_init(&foo->ctrl_handler, nr_of_controls);
 	v4l2_ctrl_new_std(&foo->ctrl_handler, &foo_ctrl_ops,
@@ -156,6 +170,9 @@ These functions are typically called right after the v4l2_ctrl_handler_init:
 			ARRAY_SIZE(exp_bias_qmenu) - 1,
 			ARRAY_SIZE(exp_bias_qmenu) / 2 - 1,
 			exp_bias_qmenu);
+	v4l2_ctrl_new_std_menu_items(&foo->ctrl_handler, &foo_ctrl_ops,
+			V4L2_CID_TEST_PATTERN, ARRAY_SIZE(test_pattern) - 1, 0,
+			0, test_pattern);
 	...
 	if (foo->ctrl_handler.error) {
 		int err = foo->ctrl_handler.error;
@@ -185,6 +202,13 @@ v4l2_ctrl_new_std_menu in that it doesn't have the mask argument and takes
 as the last argument an array of signed 64-bit integers that form an exact
 menu item list.
 
+The v4l2_ctrl_new_std_menu_items function is very similar to
+v4l2_ctrl_new_std_menu but takes an extra parameter qmenu, which is the driver
+specific menu for an otherwise standard menu control. A good example for this
+control is the test pattern control for capture/display/sensors devices that
+have the capability to generate test patterns. These test patterns are hardware
+specific, so the contents of the menu will vary from device to device.
+
 Note that if something fails, the function will return NULL or an error and
 set ctrl_handler->error to the error code. If ctrl_handler->error was already
 set, then it will just return and do nothing. This is also true for
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index 41b7732..96c5e73 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -1643,6 +1643,36 @@ struct v4l2_ctrl *v4l2_ctrl_new_std_menu(struct v4l2_ctrl_handler *hdl,
 }
 EXPORT_SYMBOL(v4l2_ctrl_new_std_menu);
 
+/* Helper function for standard menu controls with driver defined menu */
+struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(struct v4l2_ctrl_handler *hdl,
+			const struct v4l2_ctrl_ops *ops, u32 id, s32 max,
+			s32 mask, s32 def, const char * const *qmenu)
+{
+	enum v4l2_ctrl_type type;
+	const char *name;
+	u32 flags;
+	s32 step;
+	s32 min;
+
+	/* v4l2_ctrl_new_std_menu_items() should only be called for
+	 * standard controls without a standard menu.
+	 */
+	if (v4l2_ctrl_get_menu(id)) {
+		handler_set_err(hdl, -EINVAL);
+		return NULL;
+	}
+
+	v4l2_ctrl_fill(id, &name, &type, &min, &max, &step, &def, &flags);
+	if (type != V4L2_CTRL_TYPE_MENU || qmenu == NULL) {
+		handler_set_err(hdl, -EINVAL);
+		return NULL;
+	}
+	return v4l2_ctrl_new(hdl, ops, id, name, type, 0, max, mask, def,
+			     flags, qmenu, NULL, NULL);
+
+}
+EXPORT_SYMBOL(v4l2_ctrl_new_std_menu_items);
+
 /* Helper function for standard integer menu controls */
 struct v4l2_ctrl *v4l2_ctrl_new_int_menu(struct v4l2_ctrl_handler *hdl,
 			const struct v4l2_ctrl_ops *ops,
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 776605f..8db9dbe 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -351,6 +351,29 @@ 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_new_std_menu_items() - Create a new standard V4L2 menu control
+  * with driver specific menu.
+  * @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.
+  * @qmenu:	The new menu.
+  *
+  * Same as v4l2_ctrl_new_std_menu(), but @qmenu will be the driver specific
+  * menu of this control.
+  *
+  */
+struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(struct v4l2_ctrl_handler *hdl,
+			const struct v4l2_ctrl_ops *ops, u32 id, s32 max,
+			s32 mask, s32 def, const char * const *qmenu);
+
 /** v4l2_ctrl_new_int_menu() - Create a new standard V4L2 integer menu control.
   * @hdl:	The control handler.
   * @ops:	The control ops.
-- 
1.7.4.1