usb: gadget: add f_uac1 variant based on a new u_audio api

This patch adds a new function 'f_uac1'
(f_uac1 with virtual "ALSA card") that
uses recently created u_audio API. Comparing
to legacy f_uac1 function implementation it
doesn't require any real Audio codec to be
present on the device. In f_uac1 audio
streams are simply sinked to and sourced
from a virtual ALSA sound card created
using u_audio API.

Legacy f_uac1 approach is to write audio
samples directly to existing ALSA sound
card

f_uac1 approach is more generic/flexible
one - create an ALSA sound card that
represents USB Audio function and allows to
be used by userspace application that
may choose to do whatever it wants with the
data received from the USB Host and choose
to provide whatever it wants as audio data
to the USB Host.

f_uac1 also has capture support (gadget->host)
thanks to easy implementation via u_audio.
By default, capture interface has 48000kHz/2ch
configuration, same as playback channel has.

f_uac1 descriptors naming convention
uses f_uac2 driver naming convention that
makes it more common and meaningful.

Comparing to f_uac1_legacy, the f_uac1 doesn't
have volume/mute functionality. This is because
the f_uac1 volume/mute feature unit was dummy
implementation since that driver creation (2009)
and never had any real volume control or mute
functionality, so there is no any difference
here.

Since f_uac1 functionality, exposed
interface to userspace (virtual ALSA card),
input parameters are so different comparing
to f_uac1_legacy, that there is no any
reason to keep them in the same file/module,
and separate function was created.

g_audio can be built using one of existing
UAC functions (f_uac1, f_uac1_legacy or f_uac2)
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Documentation/ABI/testing/configfs-usb-gadget-uac1

+What:		/config/usb-gadget/gadget/functions/uac1.name
+Date:		June 2017
+KernelVersion:	4.14
+Description:
+		The attributes:
+
+		c_chmask - capture channel mask
+		c_srate - capture sampling rate
+		c_ssize - capture sample size (bytes)
+		p_chmask - playback channel mask
+		p_srate - playback sampling rate
+		p_ssize - playback sample size (bytes)
+		req_number - the number of pre-allocated request
+			for both capture and playback

Documentation/usb/gadget-testing.txt

@@ -20,6 +20,7 @@ provided by gadgets.
 17. UAC2 function
 18. UVC function
 19. PRINTER function
+20. UAC1 function (new API)
 
 
 1. ACM function
@@ -773,3 +774,46 @@ host:
 
 More advanced testing can be done with the prn_example
 described in Documentation/usb/gadget-printer.txt.
+
+
+20. UAC1 function (virtual ALSA card, using u_audio API)
+=================
+
+The function is provided by usb_f_uac1.ko module.
+It will create a virtual ALSA card and the audio streams are simply
+sinked to and sourced from it.
+
+Function-specific configfs interface
+------------------------------------
+
+The function name to use when creating the function directory is "uac1".
+The uac1 function provides these attributes in its function directory:
+
+	c_chmask - capture channel mask
+	c_srate - capture sampling rate
+	c_ssize - capture sample size (bytes)
+	p_chmask - playback channel mask
+	p_srate - playback sampling rate
+	p_ssize - playback sample size (bytes)
+	req_number - the number of pre-allocated request for both capture
+		     and playback
+
+The attributes have sane default values.
+
+Testing the UAC1 function
+-------------------------
+
+device: run the gadget
+host: aplay -l # should list our USB Audio Gadget
+
+This function does not require real hardware support, it just
+sends a stream of audio data to/from the host. In order to
+actually hear something at the device side, a command similar
+to this must be used at the device side:
+
+$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 &
+
+e.g.:
+
+$ arecord -f dat -t wav -D hw:CARD=UAC1Gadget,DEV=0 | \
+aplay -D default:CARD=OdroidU3

drivers/usb/gadget/Kconfig

@@ -191,6 +191,9 @@ config USB_F_MASS_STORAGE
 config USB_F_FS
 	tristate
 
+config USB_F_UAC1
+	tristate
+
 config USB_F_UAC1_LEGACY
 	tristate
 
@@ -365,6 +368,24 @@ config USB_CONFIGFS_F_FS
 	  implemented in kernel space (for instance Ethernet, serial or
 	  mass storage) and other are implemented in user space.
 
+config USB_CONFIGFS_F_UAC1
+	bool "Audio Class 1.0"
+	depends on USB_CONFIGFS
+	depends on SND
+	select USB_LIBCOMPOSITE
+	select SND_PCM
+	select USB_U_AUDIO
+	select USB_F_UAC1
+	help
+	  This Audio function implements 1 AudioControl interface,
+	  1 AudioStreaming Interface each for USB-OUT and USB-IN.
+	  This driver doesn't expect any real Audio codec to be present
+	  on the device - the audio streams are simply sinked to and
+	  sourced from a virtual ALSA sound card created. The user-space
+	  application may choose to do whatever it wants with the data
+	  received from the USB Host and choose to provide whatever it
+	  wants as audio data to the USB Host.
+
 config USB_CONFIGFS_F_UAC1_LEGACY
 	bool "Audio Class 1.0 (legacy implementation)"
 	depends on USB_CONFIGFS
@@ -375,8 +396,8 @@ config USB_CONFIGFS_F_UAC1_LEGACY
 	help
 	  This Audio function implements 1 AudioControl interface,
 	  1 AudioStreaming Interface each for USB-OUT and USB-IN.
-	  This driver requires a real Audio codec to be present
-	  on the device.
+	  This is a legacy driver and requires a real Audio codec
+	  to be present on the device.
 
 config USB_CONFIGFS_F_UAC2
 	bool "Audio Class 2.0"

drivers/usb/gadget/function/Makefile

@@ -33,6 +33,8 @@ obj-$(CONFIG_USB_F_MASS_STORAGE)+= usb_f_mass_storage.o
 usb_f_fs-y			:= f_fs.o
 obj-$(CONFIG_USB_F_FS)		+= usb_f_fs.o
 obj-$(CONFIG_USB_U_AUDIO)	+= u_audio.o
+usb_f_uac1-y			:= f_uac1.o
+obj-$(CONFIG_USB_F_UAC1)	+= usb_f_uac1.o
 usb_f_uac1_legacy-y		:= f_uac1_legacy.o u_uac1_legacy.o
 obj-$(CONFIG_USB_F_UAC1_LEGACY)	+= usb_f_uac1_legacy.o
 usb_f_uac2-y			:= f_uac2.o

drivers/usb/gadget/function/u_uac1.h

+/*
+ * u_uac1.h - Utility definitions for UAC1 function
+ *
+ * Copyright (C) 2016 Ruslan Bilovol <ruslan.bilovol@gmail.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 __U_UAC1_H
+#define __U_UAC1_H
+
+#include <linux/usb/composite.h>
+
+#define UAC1_OUT_EP_MAX_PACKET_SIZE	200
+#define UAC1_DEF_CCHMASK	0x3
+#define UAC1_DEF_CSRATE		48000
+#define UAC1_DEF_CSSIZE		2
+#define UAC1_DEF_PCHMASK	0x3
+#define UAC1_DEF_PSRATE		48000
+#define UAC1_DEF_PSSIZE		2
+#define UAC1_DEF_REQ_NUM	2
+
+
+struct f_uac1_opts {
+	struct usb_function_instance	func_inst;
+	int				c_chmask;
+	int				c_srate;
+	int				c_ssize;
+	int				p_chmask;
+	int				p_srate;
+	int				p_ssize;
+	int				req_number;
+	unsigned			bound:1;
+
+	struct mutex			lock;
+	int				refcnt;
+};
+
+#endif /* __U_UAC1_H */

drivers/usb/gadget/legacy/Kconfig

@@ -54,9 +54,10 @@ config USB_AUDIO
 	depends on SND
 	select USB_LIBCOMPOSITE
 	select SND_PCM
-	select USB_F_UAC1_LEGACY if GADGET_UAC1_LEGACY
-	select USB_F_UAC2 if !GADGET_UAC1_LEGACY
-	select USB_U_AUDIO if USB_F_UAC2
+	select USB_F_UAC1 if (GADGET_UAC1 && !GADGET_UAC1_LEGACY)
+	select USB_F_UAC1_LEGACY if (GADGET_UAC1 && GADGET_UAC1_LEGACY)
+	select USB_F_UAC2 if !GADGET_UAC1
+	select USB_U_AUDIO if (USB_F_UAC2 || USB_F_UAC1)
 	help
 	  This Gadget Audio driver is compatible with USB Audio Class
 	  specification 2.0. It implements 1 AudioControl interface,
@@ -73,11 +74,18 @@ config USB_AUDIO
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_audio".
 
+config GADGET_UAC1
+	bool "UAC 1.0"
+	depends on USB_AUDIO
+	help
+	  If you instead want older USB Audio Class specification 1.0 support
+	  with similar driver capabilities.
+
 config GADGET_UAC1_LEGACY
 	bool "UAC 1.0 (Legacy)"
-	depends on USB_AUDIO
+	depends on GADGET_UAC1
 	help
-	  If you instead want older UAC Spec-1.0 driver that also has audio
+	  If you instead want legacy UAC Spec-1.0 driver that also has audio
 	  paths hardwired to the Audio codec chip on-board and doesn't work
 	  without one.
 

drivers/usb/gadget/legacy/audio.c

@@ -20,7 +20,7 @@
 
 USB_GADGET_COMPOSITE_OPTIONS();
 
-#ifndef CONFIG_GADGET_UAC1_LEGACY
+#ifndef CONFIG_GADGET_UAC1
 #include "u_uac2.h"
 
 /* Playback(USB-IN) Default Stereo - Fl/Fr */
@@ -53,6 +53,39 @@ static int c_ssize = UAC2_DEF_CSSIZE;
 module_param(c_ssize, uint, S_IRUGO);
 MODULE_PARM_DESC(c_ssize, "Capture Sample Size(bytes)");
 #else
+#ifndef CONFIG_GADGET_UAC1_LEGACY
+#include "u_uac1.h"
+
+/* Playback(USB-IN) Default Stereo - Fl/Fr */
+static int p_chmask = UAC1_DEF_PCHMASK;
+module_param(p_chmask, uint, S_IRUGO);
+MODULE_PARM_DESC(p_chmask, "Playback Channel Mask");
+
+/* Playback Default 48 KHz */
+static int p_srate = UAC1_DEF_PSRATE;
+module_param(p_srate, uint, S_IRUGO);
+MODULE_PARM_DESC(p_srate, "Playback Sampling Rate");
+
+/* Playback Default 16bits/sample */
+static int p_ssize = UAC1_DEF_PSSIZE;
+module_param(p_ssize, uint, S_IRUGO);
+MODULE_PARM_DESC(p_ssize, "Playback Sample Size(bytes)");
+
+/* Capture(USB-OUT) Default Stereo - Fl/Fr */
+static int c_chmask = UAC1_DEF_CCHMASK;
+module_param(c_chmask, uint, S_IRUGO);
+MODULE_PARM_DESC(c_chmask, "Capture Channel Mask");
+
+/* Capture Default 48 KHz */
+static int c_srate = UAC1_DEF_CSRATE;
+module_param(c_srate, uint, S_IRUGO);
+MODULE_PARM_DESC(c_srate, "Capture Sampling Rate");
+
+/* Capture Default 16bits/sample */
+static int c_ssize = UAC1_DEF_CSSIZE;
+module_param(c_ssize, uint, S_IRUGO);
+MODULE_PARM_DESC(c_ssize, "Capture Sample Size(bytes)");
+#else /* CONFIG_GADGET_UAC1_LEGACY */
 #include "u_uac1_legacy.h"
 
 static char *fn_play = FILE_PCM_PLAYBACK;
@@ -78,6 +111,7 @@ MODULE_PARM_DESC(req_count, "ISO OUT endpoint request count");
 static int audio_buf_size = UAC1_AUDIO_BUF_SIZE;
 module_param(audio_buf_size, int, S_IRUGO);
 MODULE_PARM_DESC(audio_buf_size, "Audio buffer size");
+#endif /* CONFIG_GADGET_UAC1_LEGACY */
 #endif
 
 /* string IDs are assigned dynamically */
@@ -99,7 +133,7 @@ static struct usb_gadget_strings *audio_strings[] = {
 	NULL,
 };
 
-#ifndef CONFIG_GADGET_UAC1_LEGACY
+#ifndef CONFIG_GADGET_UAC1
 static struct usb_function_instance *fi_uac2;
 static struct usb_function *f_uac2;
 #else
@@ -164,7 +198,7 @@ static int audio_do_config(struct usb_configuration *c)
 		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
 	}
 
-#ifdef CONFIG_GADGET_UAC1_LEGACY
+#ifdef CONFIG_GADGET_UAC1
 	f_uac1 = usb_get_function(fi_uac1);
 	if (IS_ERR(f_uac1)) {
 		status = PTR_ERR(f_uac1);
@@ -204,24 +238,32 @@ static struct usb_configuration audio_config_driver = {
 
 static int audio_bind(struct usb_composite_dev *cdev)
 {
-#ifndef CONFIG_GADGET_UAC1_LEGACY
+#ifndef CONFIG_GADGET_UAC1
 	struct f_uac2_opts	*uac2_opts;
+#else
+#ifndef CONFIG_GADGET_UAC1_LEGACY
+	struct f_uac1_opts	*uac1_opts;
 #else
 	struct f_uac1_legacy_opts	*uac1_opts;
+#endif
 #endif
 	int			status;
 
-#ifndef CONFIG_GADGET_UAC1_LEGACY
+#ifndef CONFIG_GADGET_UAC1
 	fi_uac2 = usb_get_function_instance("uac2");
 	if (IS_ERR(fi_uac2))
 		return PTR_ERR(fi_uac2);
+#else
+#ifndef CONFIG_GADGET_UAC1_LEGACY
+	fi_uac1 = usb_get_function_instance("uac1");
 #else
 	fi_uac1 = usb_get_function_instance("uac1_legacy");
+#endif
 	if (IS_ERR(fi_uac1))
 		return PTR_ERR(fi_uac1);
 #endif
 
-#ifndef CONFIG_GADGET_UAC1_LEGACY
+#ifndef CONFIG_GADGET_UAC1
 	uac2_opts = container_of(fi_uac2, struct f_uac2_opts, func_inst);
 	uac2_opts->p_chmask = p_chmask;
 	uac2_opts->p_srate = p_srate;
@@ -231,6 +273,16 @@ static int audio_bind(struct usb_composite_dev *cdev)
 	uac2_opts->c_ssize = c_ssize;
 	uac2_opts->req_number = UAC2_DEF_REQ_NUM;
 #else
+#ifndef CONFIG_GADGET_UAC1_LEGACY
+	uac1_opts = container_of(fi_uac1, struct f_uac1_opts, func_inst);
+	uac1_opts->p_chmask = p_chmask;
+	uac1_opts->p_srate = p_srate;
+	uac1_opts->p_ssize = p_ssize;
+	uac1_opts->c_chmask = c_chmask;
+	uac1_opts->c_srate = c_srate;
+	uac1_opts->c_ssize = c_ssize;
+	uac1_opts->req_number = UAC1_DEF_REQ_NUM;
+#else /* CONFIG_GADGET_UAC1_LEGACY */
 	uac1_opts = container_of(fi_uac1, struct f_uac1_legacy_opts, func_inst);
 	uac1_opts->fn_play = fn_play;
 	uac1_opts->fn_cap = fn_cap;
@@ -238,6 +290,7 @@ static int audio_bind(struct usb_composite_dev *cdev)
 	uac1_opts->req_buf_size = req_buf_size;
 	uac1_opts->req_count = req_count;
 	uac1_opts->audio_buf_size = audio_buf_size;
+#endif /* CONFIG_GADGET_UAC1_LEGACY */
 #endif
 
 	status = usb_string_ids_tab(cdev, strings_dev);
@@ -269,7 +322,7 @@ static int audio_bind(struct usb_composite_dev *cdev)
 	kfree(otg_desc[0]);
 	otg_desc[0] = NULL;
 fail:
-#ifndef CONFIG_GADGET_UAC1_LEGACY
+#ifndef CONFIG_GADGET_UAC1
 	usb_put_function_instance(fi_uac2);
 #else
 	usb_put_function_instance(fi_uac1);
@@ -279,7 +332,7 @@ static int audio_bind(struct usb_composite_dev *cdev)
 
 static int audio_unbind(struct usb_composite_dev *cdev)
 {
-#ifdef CONFIG_GADGET_UAC1_LEGACY
+#ifdef CONFIG_GADGET_UAC1
 	if (!IS_ERR_OR_NULL(f_uac1))
 		usb_put_function(f_uac1);
 	if (!IS_ERR_OR_NULL(fi_uac1))