usb: gadget: uvc: configfs support in uvc function

Add support for using the uvc function as a component of USB gadgets composed
with configfs.
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NAndrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

Documentation/ABI/testing/configfs-usb-gadget-uvc

+What:		/config/usb-gadget/gadget/functions/uvc.name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	UVC function directory
+
+		streaming_maxburst	- 0..15 (ss only)
+		streaming_maxpacket	- 1..1023 (fs), 1..3072 (hs/ss)
+		streaming_interval	- 1..16
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Control descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/class
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/class/ss
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Super speed control class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/class/fs
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Full speed control class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/terminal
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Terminal descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/terminal/output
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Output terminal descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/terminal/output/default
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Default output terminal descriptors
+
+		All attributes read only:
+		iTerminal	- index of string descriptor
+		bSourceID 	- id of the terminal to which this terminal
+				is connected
+		bAssocTerminal	- id of the input terminal to which this output
+				terminal is associated
+		wTerminalType	- terminal type
+		bTerminalID	- a non-zero id of this terminal
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/terminal/camera
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Camera terminal descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/terminal/camera/default
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Default camera terminal descriptors
+
+		All attributes read only:
+		bmControls		- bitmap specifying which controls are
+					supported for the video stream
+		wOcularFocalLength	- the value of Locular
+		wObjectiveFocalLengthMax- the value of Lmin
+		wObjectiveFocalLengthMin- the value of Lmax
+		iTerminal		- index of string descriptor
+		bAssocTerminal		- id of the output terminal to which
+					this terminal is connected
+		wTerminalType		- terminal type
+		bTerminalID		- a non-zero id of this terminal
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/processing
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Processing unit descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/processing/default
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Default processing unit descriptors
+
+		All attributes read only:
+		iProcessing	- index of string descriptor
+		bmControls	- bitmap specifying which controls are
+				supported for the video stream
+		wMaxMultiplier	- maximum digital magnification x100
+		bSourceID	- id of the terminal to which this unit is
+				connected
+		bUnitID		- a non-zero id of this unit
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/header
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Control header descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/control/header/name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Specific control header descriptors
+
+dwClockFrequency
+bcdUVC
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Streaming descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/class
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Streaming class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/class/ss
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Super speed streaming class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/class/hs
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	High speed streaming class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/class/fs
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Full speed streaming class descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/color_matching
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Color matching descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/color_matching/default
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Default color matching descriptors
+
+		All attributes read only:
+		bMatrixCoefficients	- matrix used to compute luma and
+					chroma values from the color primaries
+		bTransferCharacteristics- optoelectronic transfer
+					characteristic of the source picutre,
+					also called the gamma function
+		bColorPrimaries		- color primaries and the reference
+					white
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/mjpeg
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	MJPEG format descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/mjpeg/name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Specific MJPEG format descriptors
+
+		All attributes read only,
+		except bmaControls and bDefaultFrameIndex:
+		bmaControls		- this format's data for bmaControls in
+					the streaming header
+		bmInterfaceFlags	- specifies interlace information,
+					read-only
+		bAspectRatioY		- the X dimension of the picture aspect
+					ratio, read-only
+		bAspectRatioX		- the Y dimension of the picture aspect
+					ratio, read-only
+		bmFlags			- characteristics of this format,
+					read-only
+		bDefaultFrameIndex	- optimum frame index for this stream
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/mjpeg/name/name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Specific MJPEG frame descriptors
+
+		dwFrameInterval		- indicates how frame interval can be
+					programmed; a number of values
+					separated by newline can be specified
+		dwDefaultFrameInterval	- the frame interval the device would
+					like to use as default
+		dwMaxVideoFrameBufferSize- the maximum number of bytes the
+					compressor will produce for a video
+					frame or still image
+		dwMaxBitRate		- the maximum bit rate at the shortest
+					frame interval in bps
+		dwMinBitRate		- the minimum bit rate at the longest
+					frame interval in bps
+		wHeight			- height of decoded bitmap frame in px
+		wWidth			- width of decoded bitmam frame in px
+		bmCapabilities		- still image support, fixed frame-rate
+					support
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/uncompressed
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Uncompressed format descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/uncompressed/name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Specific uncompressed format descriptors
+
+		bmaControls		- this format's data for bmaControls in
+					the streaming header
+		bmInterfaceFlags	- specifies interlace information,
+					read-only
+		bAspectRatioY		- the X dimension of the picture aspect
+					ratio, read-only
+		bAspectRatioX		- the Y dimension of the picture aspect
+					ratio, read-only
+		bDefaultFrameIndex	- optimum frame index for this stream
+		bBitsPerPixel		- number of bits per pixel used to
+					specify color in the decoded video
+					frame
+		guidFormat		- globally unique id used to identify
+					stream-encoding format
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/uncompressed/name/name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Specific uncompressed frame descriptors
+
+		dwFrameInterval		- indicates how frame interval can be
+					programmed; a number of values
+					separated by newline can be specified
+		dwDefaultFrameInterval	- the frame interval the device would
+					like to use as default
+		dwMaxVideoFrameBufferSize- the maximum number of bytes the
+					compressor will produce for a video
+					frame or still image
+		dwMaxBitRate		- the maximum bit rate at the shortest
+					frame interval in bps
+		dwMinBitRate		- the minimum bit rate at the longest
+					frame interval in bps
+		wHeight			- height of decoded bitmap frame in px
+		wWidth			- width of decoded bitmam frame in px
+		bmCapabilities		- still image support, fixed frame-rate
+					support
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/header
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Streaming header descriptors
+
+What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/header/name
+Date:		Dec 2014
+KernelVersion:	3.20
+Description:	Specific streaming header descriptors
+
+		All attributes read only:
+		bTriggerUsage		- how the host software will respond to
+					a hardware trigger interrupt event
+		bTriggerSupport		- flag specifying if hardware
+					triggering is supported
+		bStillCaptureMethod	- method of still image caputre
+					supported
+		bTerminalLink		- id of the output terminal to which
+					the video endpoint of this interface
+					is connected
+		bmInfo			- capabilities of this video streaming
+					interface

drivers/usb/gadget/Kconfig

@@ -423,6 +423,17 @@ config USB_CONFIGFS_F_HID
 
 	  For more information, see Documentation/usb/gadget_hid.txt.
 
+config USB_CONFIGFS_F_UVC
+	boolean "USB Webcam function"
+	depends on USB_CONFIGFS
+	depends on VIDEO_DEV
+	select VIDEOBUF2_VMALLOC
+	select USB_F_UVC
+	help
+	  The Webcam function acts as a composite USB Audio and Video Class
+	  device. It provides a userspace API to process UVC control requests
+	  and stream video data to the host.
+
 source "drivers/usb/gadget/legacy/Kconfig"
 
 endchoice

drivers/usb/gadget/function/Makefile

@@ -36,7 +36,7 @@ usb_f_uac1-y			:= f_uac1.o u_uac1.o
 obj-$(CONFIG_USB_F_UAC1)	+= usb_f_uac1.o
 usb_f_uac2-y			:= f_uac2.o
 obj-$(CONFIG_USB_F_UAC2)	+= usb_f_uac2.o
-usb_f_uvc-y			:= f_uvc.o uvc_queue.o uvc_v4l2.o uvc_video.o
+usb_f_uvc-y			:= f_uvc.o uvc_queue.o uvc_v4l2.o uvc_video.o uvc_configfs.o
 obj-$(CONFIG_USB_F_UVC)		+= usb_f_uvc.o
 usb_f_midi-y			:= f_midi.o
 obj-$(CONFIG_USB_F_MIDI)	+= usb_f_midi.o

drivers/usb/gadget/function/f_uvc.c

@@ -27,10 +27,11 @@
 #include <media/v4l2-dev.h>
 #include <media/v4l2-event.h>
 
+#include "u_uvc.h"
 #include "uvc.h"
+#include "uvc_configfs.h"
 #include "uvc_v4l2.h"
 #include "uvc_video.h"
-#include "u_uvc.h"
 
 unsigned int uvc_gadget_trace_param;
 
@@ -788,25 +789,104 @@ static void uvc_free_inst(struct usb_function_instance *f)
 {
 	struct f_uvc_opts *opts = fi_to_f_uvc_opts(f);
 
+	mutex_destroy(&opts->lock);
 	kfree(opts);
 }
 
 static struct usb_function_instance *uvc_alloc_inst(void)
 {
 	struct f_uvc_opts *opts;
+	struct uvc_camera_terminal_descriptor *cd;
+	struct uvc_processing_unit_descriptor *pd;
+	struct uvc_output_terminal_descriptor *od;
+	struct uvc_color_matching_descriptor *md;
+	struct uvc_descriptor_header **ctl_cls;
 
 	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 	if (!opts)
 		return ERR_PTR(-ENOMEM);
 	opts->func_inst.free_func_inst = uvc_free_inst;
-
+	mutex_init(&opts->lock);
+
+	cd = &opts->uvc_camera_terminal;
+	cd->bLength			= UVC_DT_CAMERA_TERMINAL_SIZE(3);
+	cd->bDescriptorType		= USB_DT_CS_INTERFACE;
+	cd->bDescriptorSubType		= UVC_VC_INPUT_TERMINAL;
+	cd->bTerminalID			= 1;
+	cd->wTerminalType		= cpu_to_le16(0x0201);
+	cd->bAssocTerminal		= 0;
+	cd->iTerminal			= 0;
+	cd->wObjectiveFocalLengthMin	= cpu_to_le16(0);
+	cd->wObjectiveFocalLengthMax	= cpu_to_le16(0);
+	cd->wOcularFocalLength		= cpu_to_le16(0);
+	cd->bControlSize		= 3;
+	cd->bmControls[0]		= 2;
+	cd->bmControls[1]		= 0;
+	cd->bmControls[2]		= 0;
+
+	pd = &opts->uvc_processing;
+	pd->bLength			= UVC_DT_PROCESSING_UNIT_SIZE(2);
+	pd->bDescriptorType		= USB_DT_CS_INTERFACE;
+	pd->bDescriptorSubType		= UVC_VC_PROCESSING_UNIT;
+	pd->bUnitID			= 2;
+	pd->bSourceID			= 1;
+	pd->wMaxMultiplier		= cpu_to_le16(16*1024);
+	pd->bControlSize		= 2;
+	pd->bmControls[0]		= 1;
+	pd->bmControls[1]		= 0;
+	pd->iProcessing			= 0;
+
+	od = &opts->uvc_output_terminal;
+	od->bLength			= UVC_DT_OUTPUT_TERMINAL_SIZE;
+	od->bDescriptorType		= USB_DT_CS_INTERFACE;
+	od->bDescriptorSubType		= UVC_VC_OUTPUT_TERMINAL;
+	od->bTerminalID			= 3;
+	od->wTerminalType		= cpu_to_le16(0x0101);
+	od->bAssocTerminal		= 0;
+	od->bSourceID			= 2;
+	od->iTerminal			= 0;
+
+	md = &opts->uvc_color_matching;
+	md->bLength			= UVC_DT_COLOR_MATCHING_SIZE;
+	md->bDescriptorType		= USB_DT_CS_INTERFACE;
+	md->bDescriptorSubType		= UVC_VS_COLORFORMAT;
+	md->bColorPrimaries		= 1;
+	md->bTransferCharacteristics	= 1;
+	md->bMatrixCoefficients		= 4;
+
+	/* Prepare fs control class descriptors for configfs-based gadgets */
+	ctl_cls = opts->uvc_fs_control_cls;
+	ctl_cls[0] = NULL;	/* assigned elsewhere by configfs */
+	ctl_cls[1] = (struct uvc_descriptor_header *)cd;
+	ctl_cls[2] = (struct uvc_descriptor_header *)pd;
+	ctl_cls[3] = (struct uvc_descriptor_header *)od;
+	ctl_cls[4] = NULL;	/* NULL-terminate */
+	opts->fs_control =
+		(const struct uvc_descriptor_header * const *)ctl_cls;
+
+	/* Prepare hs control class descriptors for configfs-based gadgets */
+	ctl_cls = opts->uvc_ss_control_cls;
+	ctl_cls[0] = NULL;	/* assigned elsewhere by configfs */
+	ctl_cls[1] = (struct uvc_descriptor_header *)cd;
+	ctl_cls[2] = (struct uvc_descriptor_header *)pd;
+	ctl_cls[3] = (struct uvc_descriptor_header *)od;
+	ctl_cls[4] = NULL;	/* NULL-terminate */
+	opts->ss_control =
+		(const struct uvc_descriptor_header * const *)ctl_cls;
+
+	opts->streaming_interval = 1;
+	opts->streaming_maxpacket = 1024;
+
+	uvcg_attach_configfs(opts);
 	return &opts->func_inst;
 }
 
 static void uvc_free(struct usb_function *f)
 {
 	struct uvc_device *uvc = to_uvc(f);
-
+	struct f_uvc_opts *opts = container_of(f->fi, struct f_uvc_opts,
+					       func_inst);
+	--opts->refcnt;
 	kfree(uvc);
 }
 
@@ -832,6 +912,7 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
 {
 	struct uvc_device *uvc;
 	struct f_uvc_opts *opts;
+	struct uvc_descriptor_header **strm_cls;
 
 	uvc = kzalloc(sizeof(*uvc), GFP_KERNEL);
 	if (uvc == NULL)
@@ -840,11 +921,30 @@ static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
 	uvc->state = UVC_STATE_DISCONNECTED;
 	opts = fi_to_f_uvc_opts(fi);
 
+	mutex_lock(&opts->lock);
+	if (opts->uvc_fs_streaming_cls) {
+		strm_cls = opts->uvc_fs_streaming_cls;
+		opts->fs_streaming =
+			(const struct uvc_descriptor_header * const *)strm_cls;
+	}
+	if (opts->uvc_hs_streaming_cls) {
+		strm_cls = opts->uvc_hs_streaming_cls;
+		opts->hs_streaming =
+			(const struct uvc_descriptor_header * const *)strm_cls;
+	}
+	if (opts->uvc_ss_streaming_cls) {
+		strm_cls = opts->uvc_ss_streaming_cls;
+		opts->ss_streaming =
+			(const struct uvc_descriptor_header * const *)strm_cls;
+	}
+
 	uvc->desc.fs_control = opts->fs_control;
 	uvc->desc.ss_control = opts->ss_control;
 	uvc->desc.fs_streaming = opts->fs_streaming;
 	uvc->desc.hs_streaming = opts->hs_streaming;
 	uvc->desc.ss_streaming = opts->ss_streaming;
+	++opts->refcnt;
+	mutex_unlock(&opts->lock);
 
 	/* Register the function. */
 	uvc->func.name = "uvc";

drivers/usb/gadget/function/u_uvc.h

@@ -17,6 +17,7 @@
 #define U_UVC_H
 
 #include <linux/usb/composite.h>
+#include <linux/usb/video.h>
 
 #define fi_to_f_uvc_opts(f)	container_of(f, struct f_uvc_opts, func_inst)
 
@@ -26,11 +27,60 @@ struct f_uvc_opts {
 	unsigned int					streaming_interval;
 	unsigned int					streaming_maxpacket;
 	unsigned int					streaming_maxburst;
+
+	/*
+	 * Control descriptors array pointers for full-/high-speed and
+	 * super-speed. They point by default to the uvc_fs_control_cls and
+	 * uvc_ss_control_cls arrays respectively. Legacy gadgets must
+	 * override them in their gadget bind callback.
+	 */
 	const struct uvc_descriptor_header * const	*fs_control;
 	const struct uvc_descriptor_header * const	*ss_control;
+
+	/*
+	 * Streaming descriptors array pointers for full-speed, high-speed and
+	 * super-speed. They will point to the uvc_[fhs]s_streaming_cls arrays
+	 * for configfs-based gadgets. Legacy gadgets must initialize them in
+	 * their gadget bind callback.
+	 */
 	const struct uvc_descriptor_header * const	*fs_streaming;
 	const struct uvc_descriptor_header * const	*hs_streaming;
 	const struct uvc_descriptor_header * const	*ss_streaming;
+
+	/* Default control descriptors for configfs-based gadgets. */
+	struct uvc_camera_terminal_descriptor		uvc_camera_terminal;
+	struct uvc_processing_unit_descriptor		uvc_processing;
+	struct uvc_output_terminal_descriptor		uvc_output_terminal;
+	struct uvc_color_matching_descriptor		uvc_color_matching;
+
+	/*
+	 * Control descriptors pointers arrays for full-/high-speed and
+	 * super-speed. The first element is a configurable control header
+	 * descriptor, the other elements point to the fixed default control
+	 * descriptors. Used by configfs only, must not be touched by legacy
+	 * gadgets.
+	 */
+	struct uvc_descriptor_header			*uvc_fs_control_cls[5];
+	struct uvc_descriptor_header			*uvc_ss_control_cls[5];
+
+	/*
+	 * Streaming descriptors for full-speed, high-speed and super-speed.
+	 * Used by configfs only, must not be touched by legacy gadgets. The
+	 * arrays are allocated at runtime as the number of descriptors isn't
+	 * known in advance.
+	 */
+	struct uvc_descriptor_header			**uvc_fs_streaming_cls;
+	struct uvc_descriptor_header			**uvc_hs_streaming_cls;
+	struct uvc_descriptor_header			**uvc_ss_streaming_cls;
+
+	/*
+	 * Read/write access to configfs attributes is handled by configfs.
+	 *
+	 * This lock protects the descriptors from concurrent access by
+	 * read/write and symlink creation/removal.
+	 */
+	struct mutex			lock;
+	int				refcnt;
 };
 
 void uvc_set_trace_param(unsigned int trace);

drivers/usb/gadget/function/uvc_configfs.h

+/*
+ * uvc_configfs.h
+ *
+ * Configfs support for the uvc function.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ *
+ * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef UVC_CONFIGFS_H
+#define UVC_CONFIGFS_H
+
+struct f_uvc_opts;
+
+int uvcg_attach_configfs(struct f_uvc_opts *opts);
+
+#endif /* UVC_CONFIGFS_H */