USB: gadget: add USB Audio Gadget driver
authorBryan Wu <cooloney@kernel.org>
Wed, 3 Jun 2009 13:17:58 +0000 (09:17 -0400)
committerGreg Kroah-Hartman <gregkh@suse.de>
Tue, 16 Jun 2009 04:44:47 +0000 (21:44 -0700)
Funtions added:
 - setup all the USB audio class device descriptors
 - handle class specific setup request
 - receive data from USB host by ISO transfer
 - play audio data by ALSA sound card
 - open and setup playback PCM interface
 - set default playback PCM parameters
 - provide playback functions for USB audio driver
 - provide PCM parameters set/get functions

Test on:
 - Host: Ubuntu 8.10, kernel 2.6.27
 - Gadget: EZKIT-BF548 with ASoC AD1980 codec

Todo:
 - add real Mute control code
 - add real Volume control code
 - maybe find another way to replace dynamic buffer handling
   with static buffer allocation
 - test on Windows system
 - provide control interface to handle mute/volume control
 - provide capture interface in the future
 - test on BF527, other USB device controler and other audio codec

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/usb/gadget/Kconfig
drivers/usb/gadget/Makefile
drivers/usb/gadget/audio.c [new file with mode: 0644]
drivers/usb/gadget/f_audio.c [new file with mode: 0644]
drivers/usb/gadget/u_audio.c [new file with mode: 0644]
drivers/usb/gadget/u_audio.h [new file with mode: 0644]

index 924bb7a1cecf63f56d87b708d473a9d7d519c103..ef9d9086cddc3c7fdb065469fc42f296650e895f 100644 (file)
@@ -580,6 +580,20 @@ config USB_ZERO_HNPTEST
          the "B-Peripheral" role, that device will use HNP to let this
          one serve as the USB host instead (in the "B-Host" role).
 
+config USB_AUDIO
+       tristate "Audio Gadget (EXPERIMENTAL)"
+       depends on SND
+       help
+         Gadget Audio is compatible with USB Audio Class specification 1.0.
+         It will include at least one AudioControl interface, zero or more
+         AudioStream interface and zero or more MIDIStream interface.
+
+         Gadget Audio will use on-board ALSA (CONFIG_SND) audio card to
+         playback or capture audio stream.
+
+         Say "y" to link the driver statically, or "m" to build a
+         dynamically linked module called "g_audio".
+
 config USB_ETH
        tristate "Ethernet Gadget (with CDC Ethernet support)"
        depends on NET
index 9be2fbd6f5c23bf3819ad73ab9927ba0aa064121..fc9a7dc010475be2ee5b6b67abebe23b1ac23369 100644 (file)
@@ -31,6 +31,7 @@ obj-$(CONFIG_USB_S3C_HSOTG)   += s3c-hsotg.o
 # USB gadget drivers
 #
 g_zero-objs                    := zero.o
+g_audio-objs                   := audio.o
 g_ether-objs                   := ether.o
 g_serial-objs                  := serial.o
 g_midi-objs                    := gmidi.o
@@ -40,6 +41,7 @@ g_printer-objs                        := printer.o
 g_cdc-objs                     := cdc2.o
 
 obj-$(CONFIG_USB_ZERO)         += g_zero.o
+obj-$(CONFIG_USB_AUDIO)                += g_audio.o
 obj-$(CONFIG_USB_ETH)          += g_ether.o
 obj-$(CONFIG_USB_GADGETFS)     += gadgetfs.o
 obj-$(CONFIG_USB_FILE_STORAGE) += g_file_storage.o
diff --git a/drivers/usb/gadget/audio.c b/drivers/usb/gadget/audio.c
new file mode 100644 (file)
index 0000000..94de7e8
--- /dev/null
@@ -0,0 +1,302 @@
+/*
+ * audio.c -- Audio gadget driver
+ *
+ * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ * Copyright (C) 2008 Analog Devices, Inc
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+
+#include "u_audio.h"
+
+#define DRIVER_DESC            "Linux USB Audio Gadget"
+#define DRIVER_VERSION         "Dec 18, 2008"
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Kbuild is not very cooperative with respect to linking separately
+ * compiled library objects into one module.  So for now we won't use
+ * separate compilation ... ensuring init/exit sections work to shrink
+ * the runtime footprint, and giving us at least some parts of what
+ * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
+ */
+#include "composite.c"
+#include "usbstring.c"
+#include "config.c"
+#include "epautoconf.c"
+
+#include "u_audio.c"
+#include "f_audio.c"
+
+/*-------------------------------------------------------------------------*/
+
+/* DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
+ * Instead:  allocate your own, using normal USB-IF procedures.
+ */
+
+/* Thanks to NetChip Technologies for donating this product ID. */
+#define AUDIO_VENDOR_NUM               0x0525  /* NetChip */
+#define AUDIO_PRODUCT_NUM              0xa4a1  /* Linux-USB Audio Gadget */
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_device_descriptor device_desc = {
+       .bLength =              sizeof device_desc,
+       .bDescriptorType =      USB_DT_DEVICE,
+
+       .bcdUSB =               __constant_cpu_to_le16(0x200),
+
+       .bDeviceClass =         USB_CLASS_PER_INTERFACE,
+       .bDeviceSubClass =      0,
+       .bDeviceProtocol =      0,
+       /* .bMaxPacketSize0 = f(hardware) */
+
+       /* Vendor and product id defaults change according to what configs
+        * we support.  (As does bNumConfigurations.)  These values can
+        * also be overridden by module parameters.
+        */
+       .idVendor =             __constant_cpu_to_le16(AUDIO_VENDOR_NUM),
+       .idProduct =            __constant_cpu_to_le16(AUDIO_PRODUCT_NUM),
+       /* .bcdDevice = f(hardware) */
+       /* .iManufacturer = DYNAMIC */
+       /* .iProduct = DYNAMIC */
+       /* NO SERIAL NUMBER */
+       .bNumConfigurations =   1,
+};
+
+static struct usb_otg_descriptor otg_descriptor = {
+       .bLength =              sizeof otg_descriptor,
+       .bDescriptorType =      USB_DT_OTG,
+
+       /* REVISIT SRP-only hardware is possible, although
+        * it would not be called "OTG" ...
+        */
+       .bmAttributes =         USB_OTG_SRP | USB_OTG_HNP,
+};
+
+static const struct usb_descriptor_header *otg_desc[] = {
+       (struct usb_descriptor_header *) &otg_descriptor,
+       NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+/**
+ * Handle USB audio endpoint set/get command in setup class request
+ */
+
+static int audio_set_endpoint_req(struct usb_configuration *c,
+               const struct usb_ctrlrequest *ctrl)
+{
+       struct usb_composite_dev *cdev = c->cdev;
+       int                     value = -EOPNOTSUPP;
+       u16                     ep = le16_to_cpu(ctrl->wIndex);
+       u16                     len = le16_to_cpu(ctrl->wLength);
+       u16                     w_value = le16_to_cpu(ctrl->wValue);
+
+       DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n",
+                       ctrl->bRequest, w_value, len, ep);
+
+       switch (ctrl->bRequest) {
+       case SET_CUR:
+               value = 0;
+               break;
+
+       case SET_MIN:
+               break;
+
+       case SET_MAX:
+               break;
+
+       case SET_RES:
+               break;
+
+       case SET_MEM:
+               break;
+
+       default:
+               break;
+       }
+
+       return value;
+}
+
+static int audio_get_endpoint_req(struct usb_configuration *c,
+               const struct usb_ctrlrequest *ctrl)
+{
+       struct usb_composite_dev *cdev = c->cdev;
+       int value = -EOPNOTSUPP;
+       u8 ep = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
+       u16 len = le16_to_cpu(ctrl->wLength);
+       u16 w_value = le16_to_cpu(ctrl->wValue);
+
+       DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n",
+                       ctrl->bRequest, w_value, len, ep);
+
+       switch (ctrl->bRequest) {
+       case GET_CUR:
+       case GET_MIN:
+       case GET_MAX:
+       case GET_RES:
+               value = 3;
+               break;
+       case GET_MEM:
+               break;
+       default:
+               break;
+       }
+
+       return value;
+}
+
+static int
+audio_setup(struct usb_configuration *c, const struct usb_ctrlrequest *ctrl)
+{
+       struct usb_composite_dev *cdev = c->cdev;
+       struct usb_request *req = cdev->req;
+       int value = -EOPNOTSUPP;
+       u16 w_index = le16_to_cpu(ctrl->wIndex);
+       u16 w_value = le16_to_cpu(ctrl->wValue);
+       u16 w_length = le16_to_cpu(ctrl->wLength);
+
+       /* composite driver infrastructure handles everything except
+        * Audio class messages; interface activation uses set_alt().
+        */
+       switch (ctrl->bRequestType) {
+       case USB_AUDIO_SET_ENDPOINT:
+               value = audio_set_endpoint_req(c, ctrl);
+               break;
+
+       case USB_AUDIO_GET_ENDPOINT:
+               value = audio_get_endpoint_req(c, ctrl);
+               break;
+
+       default:
+               ERROR(cdev, "Invalid control req%02x.%02x v%04x i%04x l%d\n",
+                       ctrl->bRequestType, ctrl->bRequest,
+                       w_value, w_index, w_length);
+       }
+
+       /* respond with data transfer or status phase? */
+       if (value >= 0) {
+               DBG(cdev, "Audio req%02x.%02x v%04x i%04x l%d\n",
+                       ctrl->bRequestType, ctrl->bRequest,
+                       w_value, w_index, w_length);
+               req->zero = 0;
+               req->length = value;
+               value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+               if (value < 0)
+                       ERROR(cdev, "Audio response on err %d\n", value);
+       }
+
+       /* device either stalls (value < 0) or reports success */
+       return value;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int __init audio_do_config(struct usb_configuration *c)
+{
+       /* FIXME alloc iConfiguration string, set it in c->strings */
+
+       if (gadget_is_otg(c->cdev->gadget)) {
+               c->descriptors = otg_desc;
+               c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+       }
+
+       audio_bind_config(c);
+
+       return 0;
+}
+
+static struct usb_configuration audio_config_driver = {
+       .label                  = DRIVER_DESC,
+       .bind                   = audio_do_config,
+       .setup                  = audio_setup,
+       .bConfigurationValue    = 1,
+       /* .iConfiguration = DYNAMIC */
+       .bmAttributes           = USB_CONFIG_ATT_SELFPOWER,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int __init audio_bind(struct usb_composite_dev *cdev)
+{
+       int                     gcnum;
+       int                     status;
+
+       gcnum = usb_gadget_controller_number(cdev->gadget);
+       if (gcnum >= 0)
+               device_desc.bcdDevice = cpu_to_le16(0x0300 | gcnum);
+       else {
+               ERROR(cdev, "controller '%s' not recognized; trying %s\n",
+                       cdev->gadget->name,
+                       audio_config_driver.label);
+               device_desc.bcdDevice =
+                       __constant_cpu_to_le16(0x0300 | 0x0099);
+       }
+
+       /* device descriptor strings: manufacturer, product */
+       snprintf(manufacturer, sizeof manufacturer, "%s %s with %s",
+               init_utsname()->sysname, init_utsname()->release,
+               cdev->gadget->name);
+       status = usb_string_id(cdev);
+       if (status < 0)
+               goto fail;
+       strings_dev[STRING_MANUFACTURER_IDX].id = status;
+       device_desc.iManufacturer = status;
+
+       status = usb_string_id(cdev);
+       if (status < 0)
+               goto fail;
+       strings_dev[STRING_PRODUCT_IDX].id = status;
+       device_desc.iProduct = status;
+
+       status = usb_add_config(cdev, &audio_config_driver);
+       if (status < 0)
+               goto fail;
+
+       INFO(cdev, "%s, version: %s\n", DRIVER_DESC, DRIVER_VERSION);
+       return 0;
+
+fail:
+       return status;
+}
+
+static int __exit audio_unbind(struct usb_composite_dev *cdev)
+{
+       return 0;
+}
+
+static struct usb_composite_driver audio_driver = {
+       .name           = "g_audio",
+       .dev            = &device_desc,
+       .strings        = audio_strings,
+       .bind           = audio_bind,
+       .unbind         = __exit_p(audio_unbind),
+};
+
+static int __init init(void)
+{
+       return usb_composite_register(&audio_driver);
+}
+module_init(init);
+
+static void __exit cleanup(void)
+{
+       usb_composite_unregister(&audio_driver);
+}
+module_exit(cleanup);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Bryan Wu <cooloney@kernel.org>");
+MODULE_LICENSE("GPL");
+
diff --git a/drivers/usb/gadget/f_audio.c b/drivers/usb/gadget/f_audio.c
new file mode 100644 (file)
index 0000000..66527ba
--- /dev/null
@@ -0,0 +1,707 @@
+/*
+ * f_audio.c -- USB Audio class function driver
+  *
+ * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ * Copyright (C) 2008 Analog Devices, Inc
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <asm/atomic.h>
+
+#include "u_audio.h"
+
+#define OUT_EP_MAX_PACKET_SIZE 200
+static int req_buf_size = OUT_EP_MAX_PACKET_SIZE;
+module_param(req_buf_size, int, S_IRUGO);
+MODULE_PARM_DESC(req_buf_size, "ISO OUT endpoint request buffer size");
+
+static int req_count = 256;
+module_param(req_count, int, S_IRUGO);
+MODULE_PARM_DESC(req_count, "ISO OUT endpoint request count");
+
+static int audio_buf_size = 48000;
+module_param(audio_buf_size, int, S_IRUGO);
+MODULE_PARM_DESC(audio_buf_size, "Audio buffer size");
+
+/*
+ * DESCRIPTORS ... most are static, but strings and full
+ * configuration descriptors are built on demand.
+ */
+
+/*
+ * We have two interfaces- AudioControl and AudioStreaming
+ * TODO: only supcard playback currently
+ */
+#define F_AUDIO_AC_INTERFACE   0
+#define F_AUDIO_AS_INTERFACE   1
+#define F_AUDIO_NUM_INTERFACES 2
+
+/* B.3.1  Standard AC Interface Descriptor */
+static struct usb_interface_descriptor ac_interface_desc __initdata = {
+       .bLength =              USB_DT_INTERFACE_SIZE,
+       .bDescriptorType =      USB_DT_INTERFACE,
+       .bNumEndpoints =        0,
+       .bInterfaceClass =      USB_CLASS_AUDIO,
+       .bInterfaceSubClass =   USB_SUBCLASS_AUDIOCONTROL,
+};
+
+DECLARE_USB_AC_HEADER_DESCRIPTOR(2);
+
+#define USB_DT_AC_HEADER_LENGH USB_DT_AC_HEADER_SIZE(F_AUDIO_NUM_INTERFACES)
+/* B.3.2  Class-Specific AC Interface Descriptor */
+static struct usb_ac_header_descriptor_2 ac_header_desc = {
+       .bLength =              USB_DT_AC_HEADER_LENGH,
+       .bDescriptorType =      USB_DT_CS_INTERFACE,
+       .bDescriptorSubtype =   HEADER,
+       .bcdADC =               __constant_cpu_to_le16(0x0100),
+       .wTotalLength =         __constant_cpu_to_le16(USB_DT_AC_HEADER_LENGH),
+       .bInCollection =        F_AUDIO_NUM_INTERFACES,
+       .baInterfaceNr = {
+               [0] =           F_AUDIO_AC_INTERFACE,
+               [1] =           F_AUDIO_AS_INTERFACE,
+       }
+};
+
+#define INPUT_TERMINAL_ID      1
+static struct usb_input_terminal_descriptor input_terminal_desc = {
+       .bLength =              USB_DT_AC_INPUT_TERMINAL_SIZE,
+       .bDescriptorType =      USB_DT_CS_INTERFACE,
+       .bDescriptorSubtype =   INPUT_TERMINAL,
+       .bTerminalID =          INPUT_TERMINAL_ID,
+       .wTerminalType =        USB_AC_TERMINAL_STREAMING,
+       .bAssocTerminal =       0,
+       .wChannelConfig =       0x3,
+};
+
+DECLARE_USB_AC_FEATURE_UNIT_DESCRIPTOR(0);
+
+#define FEATURE_UNIT_ID                2
+static struct usb_ac_feature_unit_descriptor_0 feature_unit_desc = {
+       .bLength                = USB_DT_AC_FEATURE_UNIT_SIZE(0),
+       .bDescriptorType        = USB_DT_CS_INTERFACE,
+       .bDescriptorSubtype     = FEATURE_UNIT,
+       .bUnitID                = FEATURE_UNIT_ID,
+       .bSourceID              = INPUT_TERMINAL_ID,
+       .bControlSize           = 2,
+       .bmaControls[0]         = (FU_MUTE | FU_VOLUME),
+};
+
+static struct usb_audio_control mute_control = {
+       .list = LIST_HEAD_INIT(mute_control.list),
+       .name = "Mute Control",
+       .type = MUTE_CONTROL,
+       /* Todo: add real Mute control code */
+       .set = generic_set_cmd,
+       .get = generic_get_cmd,
+};
+
+static struct usb_audio_control volume_control = {
+       .list = LIST_HEAD_INIT(volume_control.list),
+       .name = "Volume Control",
+       .type = VOLUME_CONTROL,
+       /* Todo: add real Volume control code */
+       .set = generic_set_cmd,
+       .get = generic_get_cmd,
+};
+
+static struct usb_audio_control_selector feature_unit = {
+       .list = LIST_HEAD_INIT(feature_unit.list),
+       .id = FEATURE_UNIT_ID,
+       .name = "Mute & Volume Control",
+       .type = FEATURE_UNIT,
+       .desc = (struct usb_descriptor_header *)&feature_unit_desc,
+};
+
+#define OUTPUT_TERMINAL_ID     3
+static struct usb_output_terminal_descriptor output_terminal_desc = {
+       .bLength                = USB_DT_AC_OUTPUT_TERMINAL_SIZE,
+       .bDescriptorType        = USB_DT_CS_INTERFACE,
+       .bDescriptorSubtype     = OUTPUT_TERMINAL,
+       .bTerminalID            = OUTPUT_TERMINAL_ID,
+       .wTerminalType          = USB_AC_OUTPUT_TERMINAL_SPEAKER,
+       .bAssocTerminal         = FEATURE_UNIT_ID,
+       .bSourceID              = FEATURE_UNIT_ID,
+};
+
+/* B.4.1  Standard AS Interface Descriptor */
+static struct usb_interface_descriptor as_interface_alt_0_desc = {
+       .bLength =              USB_DT_INTERFACE_SIZE,
+       .bDescriptorType =      USB_DT_INTERFACE,
+       .bAlternateSetting =    0,
+       .bNumEndpoints =        0,
+       .bInterfaceClass =      USB_CLASS_AUDIO,
+       .bInterfaceSubClass =   USB_SUBCLASS_AUDIOSTREAMING,
+};
+
+static struct usb_interface_descriptor as_interface_alt_1_desc = {
+       .bLength =              USB_DT_INTERFACE_SIZE,
+       .bDescriptorType =      USB_DT_INTERFACE,
+       .bAlternateSetting =    1,
+       .bNumEndpoints =        1,
+       .bInterfaceClass =      USB_CLASS_AUDIO,
+       .bInterfaceSubClass =   USB_SUBCLASS_AUDIOSTREAMING,
+};
+
+/* B.4.2  Class-Specific AS Interface Descriptor */
+static struct usb_as_header_descriptor as_header_desc = {
+       .bLength =              USB_DT_AS_HEADER_SIZE,
+       .bDescriptorType =      USB_DT_CS_INTERFACE,
+       .bDescriptorSubtype =   AS_GENERAL,
+       .bTerminalLink =        INPUT_TERMINAL_ID,
+       .bDelay =               1,
+       .wFormatTag =           USB_AS_AUDIO_FORMAT_TYPE_I_PCM,
+};
+
+DECLARE_USB_AS_FORMAT_TYPE_I_DISCRETE_DESC(1);
+
+static struct usb_as_formate_type_i_discrete_descriptor_1 as_type_i_desc = {
+       .bLength =              USB_AS_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(1),
+       .bDescriptorType =      USB_DT_CS_INTERFACE,
+       .bDescriptorSubtype =   FORMAT_TYPE,
+       .bFormatType =          USB_AS_FORMAT_TYPE_I,
+       .bSubframeSize =        2,
+       .bBitResolution =       16,
+       .bSamFreqType =         1,
+};
+
+/* Standard ISO OUT Endpoint Descriptor */
+static struct usb_endpoint_descriptor as_out_ep_desc __initdata = {
+       .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
+       .bDescriptorType =      USB_DT_ENDPOINT,
+       .bEndpointAddress =     USB_DIR_OUT,
+       .bmAttributes =         USB_AS_ENDPOINT_ADAPTIVE
+                               | USB_ENDPOINT_XFER_ISOC,
+       .wMaxPacketSize =       __constant_cpu_to_le16(OUT_EP_MAX_PACKET_SIZE),
+       .bInterval =            4,
+};
+
+/* Class-specific AS ISO OUT Endpoint Descriptor */
+static struct usb_as_iso_endpoint_descriptor as_iso_out_desc __initdata = {
+       .bLength =              USB_AS_ISO_ENDPOINT_DESC_SIZE,
+       .bDescriptorType =      USB_DT_CS_ENDPOINT,
+       .bDescriptorSubtype =   EP_GENERAL,
+       .bmAttributes =         1,
+       .bLockDelayUnits =      1,
+       .wLockDelay =           __constant_cpu_to_le16(1),
+};
+
+static struct usb_descriptor_header *f_audio_desc[] __initdata = {
+       (struct usb_descriptor_header *)&ac_interface_desc,
+       (struct usb_descriptor_header *)&ac_header_desc,
+
+       (struct usb_descriptor_header *)&input_terminal_desc,
+       (struct usb_descriptor_header *)&output_terminal_desc,
+       (struct usb_descriptor_header *)&feature_unit_desc,
+
+       (struct usb_descriptor_header *)&as_interface_alt_0_desc,
+       (struct usb_descriptor_header *)&as_interface_alt_1_desc,
+       (struct usb_descriptor_header *)&as_header_desc,
+
+       (struct usb_descriptor_header *)&as_type_i_desc,
+
+       (struct usb_descriptor_header *)&as_out_ep_desc,
+       (struct usb_descriptor_header *)&as_iso_out_desc,
+       NULL,
+};
+
+/* string IDs are assigned dynamically */
+
+#define STRING_MANUFACTURER_IDX                0
+#define STRING_PRODUCT_IDX             1
+
+static char manufacturer[50];
+
+static struct usb_string strings_dev[] = {
+       [STRING_MANUFACTURER_IDX].s = manufacturer,
+       [STRING_PRODUCT_IDX].s = DRIVER_DESC,
+       {  } /* end of list */
+};
+
+static struct usb_gadget_strings stringtab_dev = {
+       .language       = 0x0409,       /* en-us */
+       .strings        = strings_dev,
+};
+
+static struct usb_gadget_strings *audio_strings[] = {
+       &stringtab_dev,
+       NULL,
+};
+
+/*
+ * This function is an ALSA sound card following USB Audio Class Spec 1.0.
+ */
+
+/*-------------------------------------------------------------------------*/
+struct f_audio_buf {
+       u8 *buf;
+       int actual;
+       struct list_head list;
+};
+
+static struct f_audio_buf *f_audio_buffer_alloc(int buf_size)
+{
+       struct f_audio_buf *copy_buf;
+
+       copy_buf = kzalloc(sizeof *copy_buf, GFP_ATOMIC);
+       if (!copy_buf)
+               return (struct f_audio_buf *)-ENOMEM;
+
+       copy_buf->buf = kzalloc(buf_size, GFP_ATOMIC);
+       if (!copy_buf->buf) {
+               kfree(copy_buf);
+               return (struct f_audio_buf *)-ENOMEM;
+       }
+
+       return copy_buf;
+}
+
+static void f_audio_buffer_free(struct f_audio_buf *audio_buf)
+{
+       kfree(audio_buf->buf);
+       kfree(audio_buf);
+}
+/*-------------------------------------------------------------------------*/
+
+struct f_audio {
+       struct gaudio                   card;
+
+       /* endpoints handle full and/or high speeds */
+       struct usb_ep                   *out_ep;
+       struct usb_endpoint_descriptor  *out_desc;
+
+       spinlock_t                      lock;
+       struct f_audio_buf *copy_buf;
+       struct work_struct playback_work;
+       struct list_head play_queue;
+
+       /* Control Set command */
+       struct list_head cs;
+       u8 set_cmd;
+       struct usb_audio_control *set_con;
+};
+
+static inline struct f_audio *func_to_audio(struct usb_function *f)
+{
+       return container_of(f, struct f_audio, card.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void f_audio_playback_work(struct work_struct *data)
+{
+       struct f_audio *audio = container_of(data, struct f_audio,
+                                       playback_work);
+       struct f_audio_buf *play_buf;
+
+       spin_lock_irq(&audio->lock);
+       if (list_empty(&audio->play_queue)) {
+               spin_unlock_irq(&audio->lock);
+               return;
+       }
+       play_buf = list_first_entry(&audio->play_queue,
+                       struct f_audio_buf, list);
+       list_del(&play_buf->list);
+       spin_unlock_irq(&audio->lock);
+
+       u_audio_playback(&audio->card, play_buf->buf, play_buf->actual);
+       f_audio_buffer_free(play_buf);
+
+       return;
+}
+
+static int f_audio_out_ep_complete(struct usb_ep *ep, struct usb_request *req)
+{
+       struct f_audio *audio = req->context;
+       struct usb_composite_dev *cdev = audio->card.func.config->cdev;
+       struct f_audio_buf *copy_buf = audio->copy_buf;
+       int err;
+
+       if (!copy_buf)
+               return -EINVAL;
+
+       /* Copy buffer is full, add it to the play_queue */
+       if (audio_buf_size - copy_buf->actual < req->actual) {
+               list_add_tail(&copy_buf->list, &audio->play_queue);
+               schedule_work(&audio->playback_work);
+               copy_buf = f_audio_buffer_alloc(audio_buf_size);
+               if (copy_buf < 0)
+                       return -ENOMEM;
+       }
+
+       memcpy(copy_buf->buf + copy_buf->actual, req->buf, req->actual);
+       copy_buf->actual += req->actual;
+       audio->copy_buf = copy_buf;
+
+       err = usb_ep_queue(ep, req, GFP_ATOMIC);
+       if (err)
+               ERROR(cdev, "%s queue req: %d\n", ep->name, err);
+
+       return 0;
+
+}
+
+static void f_audio_complete(struct usb_ep *ep, struct usb_request *req)
+{
+       struct f_audio *audio = req->context;
+       int status = req->status;
+       u32 data = 0;
+       struct usb_ep *out_ep = audio->out_ep;
+
+       switch (status) {
+
+       case 0:                         /* normal completion? */
+               if (ep == out_ep)
+                       f_audio_out_ep_complete(ep, req);
+               else if (audio->set_con) {
+                       memcpy(&data, req->buf, req->length);
+                       audio->set_con->set(audio->set_con, audio->set_cmd,
+                                       le16_to_cpu(data));
+                       audio->set_con = NULL;
+               }
+               break;
+       default:
+               break;
+       }
+}
+
+static int audio_set_intf_req(struct usb_function *f,
+               const struct usb_ctrlrequest *ctrl)
+{
+       struct f_audio          *audio = func_to_audio(f);
+       struct usb_composite_dev *cdev = f->config->cdev;
+       struct usb_request      *req = cdev->req;
+       u8                      id = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
+       u16                     len = le16_to_cpu(ctrl->wLength);
+       u16                     w_value = le16_to_cpu(ctrl->wValue);
+       u8                      con_sel = (w_value >> 8) & 0xFF;
+       u8                      cmd = (ctrl->bRequest & 0x0F);
+       struct usb_audio_control_selector *cs;
+       struct usb_audio_control *con;
+
+       DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, entity %d\n",
+                       ctrl->bRequest, w_value, len, id);
+
+       list_for_each_entry(cs, &audio->cs, list) {
+               if (cs->id == id) {
+                       list_for_each_entry(con, &cs->control, list) {
+                               if (con->type == con_sel) {
+                                       audio->set_con = con;
+                                       break;
+                               }
+                       }
+                       break;
+               }
+       }
+
+       audio->set_cmd = cmd;
+       req->context = audio;
+       req->complete = f_audio_complete;
+
+       return len;
+}
+
+static int audio_get_intf_req(struct usb_function *f,
+               const struct usb_ctrlrequest *ctrl)
+{
+       struct f_audio          *audio = func_to_audio(f);
+       struct usb_composite_dev *cdev = f->config->cdev;
+       struct usb_request      *req = cdev->req;
+       int                     value = -EOPNOTSUPP;
+       u8                      id = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
+       u16                     len = le16_to_cpu(ctrl->wLength);
+       u16                     w_value = le16_to_cpu(ctrl->wValue);
+       u8                      con_sel = (w_value >> 8) & 0xFF;
+       u8                      cmd = (ctrl->bRequest & 0x0F);
+       struct usb_audio_control_selector *cs;
+       struct usb_audio_control *con;
+
+       DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, entity %d\n",
+                       ctrl->bRequest, w_value, len, id);
+
+       list_for_each_entry(cs, &audio->cs, list) {
+               if (cs->id == id) {
+                       list_for_each_entry(con, &cs->control, list) {
+                               if (con->type == con_sel && con->get) {
+                                       value = con->get(con, cmd);
+                                       break;
+                               }
+                       }
+                       break;
+               }
+       }
+
+       req->context = audio;
+       req->complete = f_audio_complete;
+       memcpy(req->buf, &value, len);
+
+       return len;
+}
+
+static int
+f_audio_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+       struct usb_composite_dev *cdev = f->config->cdev;
+       struct usb_request      *req = cdev->req;
+       int                     value = -EOPNOTSUPP;
+       u16                     w_index = le16_to_cpu(ctrl->wIndex);
+       u16                     w_value = le16_to_cpu(ctrl->wValue);
+       u16                     w_length = le16_to_cpu(ctrl->wLength);
+
+       /* composite driver infrastructure handles everything except
+        * Audio class messages; interface activation uses set_alt().
+        */
+       switch (ctrl->bRequestType) {
+       case USB_AUDIO_SET_INTF:
+               value = audio_set_intf_req(f, ctrl);
+               break;
+
+       case USB_AUDIO_GET_INTF:
+               value = audio_get_intf_req(f, ctrl);
+               break;
+
+       default:
+               ERROR(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
+                       ctrl->bRequestType, ctrl->bRequest,
+                       w_value, w_index, w_length);
+       }
+
+       /* respond with data transfer or status phase? */
+       if (value >= 0) {
+               DBG(cdev, "audio req%02x.%02x v%04x i%04x l%d\n",
+                       ctrl->bRequestType, ctrl->bRequest,
+                       w_value, w_index, w_length);
+               req->zero = 0;
+               req->length = value;
+               value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+               if (value < 0)
+                       ERROR(cdev, "audio response on err %d\n", value);
+       }
+
+       /* device either stalls (value < 0) or reports success */
+       return value;
+}
+
+static int f_audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+       struct f_audio          *audio = func_to_audio(f);
+       struct usb_composite_dev *cdev = f->config->cdev;
+       struct usb_ep *out_ep = audio->out_ep;
+       struct usb_request *req;
+       int i = 0, err = 0;
+
+       DBG(cdev, "intf %d, alt %d\n", intf, alt);
+
+       if (intf == 1) {
+               if (alt == 1) {
+                       usb_ep_enable(out_ep, audio->out_desc);
+                       out_ep->driver_data = audio;
+                       audio->copy_buf = f_audio_buffer_alloc(audio_buf_size);
+
+                       /*
+                        * allocate a bunch of read buffers
+                        * and queue them all at once.
+                        */
+                       for (i = 0; i < req_count && err == 0; i++) {
+                               req = usb_ep_alloc_request(out_ep, GFP_ATOMIC);
+                               if (req) {
+                                       req->buf = kzalloc(req_buf_size,
+                                                       GFP_ATOMIC);
+                                       if (req->buf) {
+                                               req->length = req_buf_size;
+                                               req->context = audio;
+                                               req->complete =
+                                                       f_audio_complete;
+                                               err = usb_ep_queue(out_ep,
+                                                       req, GFP_ATOMIC);
+                                               if (err)
+                                                       ERROR(cdev,
+                                                       "%s queue req: %d\n",
+                                                       out_ep->name, err);
+                                       } else
+                                               err = -ENOMEM;
+                               } else
+                                       err = -ENOMEM;
+                       }
+
+               } else {
+                       struct f_audio_buf *copy_buf = audio->copy_buf;
+                       if (copy_buf) {
+                               list_add_tail(&copy_buf->list,
+                                               &audio->play_queue);
+                               schedule_work(&audio->playback_work);
+                       }
+               }
+       }
+
+       return err;
+}
+
+static void f_audio_disable(struct usb_function *f)
+{
+       return;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void f_audio_build_desc(struct f_audio *audio)
+{
+       struct gaudio *card = &audio->card;
+       u8 *sam_freq;
+       int rate;
+
+       /* Set channel numbers */
+       input_terminal_desc.bNrChannels = u_audio_get_playback_channels(card);
+       as_type_i_desc.bNrChannels = u_audio_get_playback_channels(card);
+
+       /* Set sample rates */
+       rate = u_audio_get_playback_rate(card);
+       sam_freq = as_type_i_desc.tSamFreq[0];
+       memcpy(sam_freq, &rate, 3);
+
+       /* Todo: Set Sample bits and other parameters */
+
+       return;
+}
+
+/* audio function driver setup/binding */
+static int __init
+f_audio_bind(struct usb_configuration *c, struct usb_function *f)
+{
+       struct usb_composite_dev *cdev = c->cdev;
+       struct f_audio          *audio = func_to_audio(f);
+       int                     status;
+       struct usb_ep           *ep;
+
+       f_audio_build_desc(audio);
+
+       /* allocate instance-specific interface IDs, and patch descriptors */
+       status = usb_interface_id(c, f);
+       if (status < 0)
+               goto fail;
+       ac_interface_desc.bInterfaceNumber = status;
+
+       status = usb_interface_id(c, f);
+       if (status < 0)
+               goto fail;
+       as_interface_alt_0_desc.bInterfaceNumber = status;
+       as_interface_alt_1_desc.bInterfaceNumber = status;
+
+       status = -ENODEV;
+
+       /* allocate instance-specific endpoints */
+       ep = usb_ep_autoconfig(cdev->gadget, &as_out_ep_desc);
+       if (!ep)
+               goto fail;
+       audio->out_ep = ep;
+       ep->driver_data = cdev; /* claim */
+
+       status = -ENOMEM;
+
+       /* supcard all relevant hardware speeds... we expect that when
+        * hardware is dual speed, all bulk-capable endpoints work at
+        * both speeds
+        */
+
+       /* copy descriptors, and track endpoint copies */
+       if (gadget_is_dualspeed(c->cdev->gadget)) {
+               c->highspeed = true;
+               f->hs_descriptors = usb_copy_descriptors(f_audio_desc);
+       } else
+               f->descriptors = usb_copy_descriptors(f_audio_desc);
+
+       return 0;
+
+fail:
+
+       return status;
+}
+
+static void
+f_audio_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+       struct f_audio          *audio = func_to_audio(f);
+
+       usb_free_descriptors(f->descriptors);
+       kfree(audio);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Todo: add more control selecotor dynamically */
+int __init control_selector_init(struct f_audio *audio)
+{
+       INIT_LIST_HEAD(&audio->cs);
+       list_add(&feature_unit.list, &audio->cs);
+
+       INIT_LIST_HEAD(&feature_unit.control);
+       list_add(&mute_control.list, &feature_unit.control);
+       list_add(&volume_control.list, &feature_unit.control);
+
+       volume_control.data[_CUR] = 0xffc0;
+       volume_control.data[_MIN] = 0xe3a0;
+       volume_control.data[_MAX] = 0xfff0;
+       volume_control.data[_RES] = 0x0030;
+
+       return 0;
+}
+
+/**
+ * audio_bind_config - add USB audio fucntion to a configuration
+ * @c: the configuration to supcard the USB audio function
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ */
+int __init audio_bind_config(struct usb_configuration *c)
+{
+       struct f_audio *audio;
+       int status;
+
+       /* allocate and initialize one new instance */
+       audio = kzalloc(sizeof *audio, GFP_KERNEL);
+       if (!audio)
+               return -ENOMEM;
+
+       audio->card.func.name = "g_audio";
+       audio->card.gadget = c->cdev->gadget;
+
+       INIT_LIST_HEAD(&audio->play_queue);
+       spin_lock_init(&audio->lock);
+
+       /* set up ASLA audio devices */
+       status = gaudio_setup(&audio->card);
+       if (status < 0)
+               goto setup_fail;
+
+       audio->card.func.strings = audio_strings;
+       audio->card.func.bind = f_audio_bind;
+       audio->card.func.unbind = f_audio_unbind;
+       audio->card.func.set_alt = f_audio_set_alt;
+       audio->card.func.setup = f_audio_setup;
+       audio->card.func.disable = f_audio_disable;
+       audio->out_desc = &as_out_ep_desc;
+
+       control_selector_init(audio);
+
+       INIT_WORK(&audio->playback_work, f_audio_playback_work);
+
+       status = usb_add_function(c, &audio->card.func);
+       if (status)
+               goto add_fail;
+
+       INFO(c->cdev, "audio_buf_size %d, req_buf_size %d, req_count %d\n",
+               audio_buf_size, req_buf_size, req_count);
+
+       return status;
+
+add_fail:
+       gaudio_cleanup(&audio->card);
+setup_fail:
+       kfree(audio);
+       return status;
+}
diff --git a/drivers/usb/gadget/u_audio.c b/drivers/usb/gadget/u_audio.c
new file mode 100644 (file)
index 0000000..0f3d22f
--- /dev/null
@@ -0,0 +1,319 @@
+/*
+ * u_audio.c -- ALSA audio utilities for Gadget stack
+ *
+ * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ * Copyright (C) 2008 Analog Devices, Inc
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/ctype.h>
+#include <linux/random.h>
+#include <linux/syscalls.h>
+
+#include "u_audio.h"
+
+/*
+ * This component encapsulates the ALSA devices for USB audio gadget
+ */
+
+#define FILE_PCM_PLAYBACK      "/dev/snd/pcmC0D0p"
+#define FILE_PCM_CAPTURE       "/dev/snd/pcmC0D0c"
+#define FILE_CONTROL           "/dev/snd/controlC0"
+
+static char *fn_play = FILE_PCM_PLAYBACK;
+module_param(fn_play, charp, S_IRUGO);
+MODULE_PARM_DESC(fn_play, "Playback PCM device file name");
+
+static char *fn_cap = FILE_PCM_CAPTURE;
+module_param(fn_cap, charp, S_IRUGO);
+MODULE_PARM_DESC(fn_cap, "Capture PCM device file name");
+
+static char *fn_cntl = FILE_CONTROL;
+module_param(fn_cntl, charp, S_IRUGO);
+MODULE_PARM_DESC(fn_cntl, "Control device file name");
+
+/*-------------------------------------------------------------------------*/
+
+/**
+ * Some ALSA internal helper functions
+ */
+static int snd_interval_refine_set(struct snd_interval *i, unsigned int val)
+{
+       struct snd_interval t;
+       t.empty = 0;
+       t.min = t.max = val;
+       t.openmin = t.openmax = 0;
+       t.integer = 1;
+       return snd_interval_refine(i, &t);
+}
+
+static int _snd_pcm_hw_param_set(struct snd_pcm_hw_params *params,
+                                snd_pcm_hw_param_t var, unsigned int val,
+                                int dir)
+{
+       int changed;
+       if (hw_is_mask(var)) {
+               struct snd_mask *m = hw_param_mask(params, var);
+               if (val == 0 && dir < 0) {
+                       changed = -EINVAL;
+                       snd_mask_none(m);
+               } else {
+                       if (dir > 0)
+                               val++;
+                       else if (dir < 0)
+                               val--;
+                       changed = snd_mask_refine_set(
+                                       hw_param_mask(params, var), val);
+               }
+       } else if (hw_is_interval(var)) {
+               struct snd_interval *i = hw_param_interval(params, var);
+               if (val == 0 && dir < 0) {
+                       changed = -EINVAL;
+                       snd_interval_none(i);
+               } else if (dir == 0)
+                       changed = snd_interval_refine_set(i, val);
+               else {
+                       struct snd_interval t;
+                       t.openmin = 1;
+                       t.openmax = 1;
+                       t.empty = 0;
+                       t.integer = 0;
+                       if (dir < 0) {
+                               t.min = val - 1;
+                               t.max = val;
+                       } else {
+                               t.min = val;
+                               t.max = val+1;
+                       }
+                       changed = snd_interval_refine(i, &t);
+               }
+       } else
+               return -EINVAL;
+       if (changed) {
+               params->cmask |= 1 << var;
+               params->rmask |= 1 << var;
+       }
+       return changed;
+}
+/*-------------------------------------------------------------------------*/
+
+/**
+ * Set default hardware params
+ */
+static int playback_default_hw_params(struct gaudio_snd_dev *snd)
+{
+       struct snd_pcm_substream *substream = snd->substream;
+       struct snd_pcm_hw_params *params;
+       snd_pcm_sframes_t result;
+
+       /*
+       * SNDRV_PCM_ACCESS_RW_INTERLEAVED,
+       * SNDRV_PCM_FORMAT_S16_LE
+       * CHANNELS: 2
+       * RATE: 48000
+       */
+       snd->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
+       snd->format = SNDRV_PCM_FORMAT_S16_LE;
+       snd->channels = 2;
+       snd->rate = 48000;
+
+       params = kzalloc(sizeof(*params), GFP_KERNEL);
+       if (!params)
+               return -ENOMEM;
+
+       _snd_pcm_hw_params_any(params);
+       _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_ACCESS,
+                       snd->access, 0);
+       _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_FORMAT,
+                       snd->format, 0);
+       _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_CHANNELS,
+                       snd->channels, 0);
+       _snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_RATE,
+                       snd->rate, 0);
+
+       snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
+       snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_HW_PARAMS, params);
+
+       result = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_PREPARE, NULL);
+       if (result < 0) {
+               ERROR(snd->card,
+                       "Preparing sound card failed: %d\n", (int)result);
+               kfree(params);
+               return result;
+       }
+
+       /* Store the hardware parameters */
+       snd->access = params_access(params);
+       snd->format = params_format(params);
+       snd->channels = params_channels(params);
+       snd->rate = params_rate(params);
+
+       kfree(params);
+
+       INFO(snd->card,
+               "Hardware params: access %x, format %x, channels %d, rate %d\n",
+               snd->access, snd->format, snd->channels, snd->rate);
+
+       return 0;
+}
+
+/**
+ * Playback audio buffer data by ALSA PCM device
+ */
+static size_t u_audio_playback(struct gaudio *card, void *buf, size_t count)
+{
+       struct gaudio_snd_dev   *snd = &card->playback;
+       struct snd_pcm_substream *substream = snd->substream;
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       mm_segment_t old_fs;
+       ssize_t result;
+       snd_pcm_sframes_t frames;
+
+try_again:
+       if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
+               runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
+               result = snd_pcm_kernel_ioctl(substream,
+                               SNDRV_PCM_IOCTL_PREPARE, NULL);
+               if (result < 0) {
+                       ERROR(card, "Preparing sound card failed: %d\n",
+                                       (int)result);
+                       return result;
+               }
+       }
+
+       frames = bytes_to_frames(runtime, count);
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+       result = snd_pcm_lib_write(snd->substream, buf, frames);
+       if (result != frames) {
+               ERROR(card, "Playback error: %d\n", (int)result);
+               set_fs(old_fs);
+               goto try_again;
+       }
+       set_fs(old_fs);
+
+       return 0;
+}
+
+static int u_audio_get_playback_channels(struct gaudio *card)
+{
+       return card->playback.channels;
+}
+
+static int u_audio_get_playback_rate(struct gaudio *card)
+{
+       return card->playback.rate;
+}
+
+/**
+ * Open ALSA PCM and control device files
+ * Initial the PCM or control device
+ */
+static int gaudio_open_snd_dev(struct gaudio *card)
+{
+       struct snd_pcm_file *pcm_file;
+       struct gaudio_snd_dev *snd;
+
+       if (!card)
+               return -ENODEV;
+
+       /* Open control device */
+       snd = &card->control;
+       snd->filp = filp_open(fn_cntl, O_RDWR, 0);
+       if (IS_ERR(snd->filp)) {
+               int ret = PTR_ERR(snd->filp);
+               ERROR(card, "unable to open sound control device file: %s\n",
+                               fn_cntl);
+               snd->filp = NULL;
+               return ret;
+       }
+       snd->card = card;
+
+       /* Open PCM playback device and setup substream */
+       snd = &card->playback;
+       snd->filp = filp_open(fn_play, O_WRONLY, 0);
+       if (IS_ERR(snd->filp)) {
+               ERROR(card, "No such PCM playback device: %s\n", fn_play);
+               snd->filp = NULL;
+       }
+       pcm_file = snd->filp->private_data;
+       snd->substream = pcm_file->substream;
+       snd->card = card;
+       playback_default_hw_params(snd);
+
+       /* Open PCM capture device and setup substream */
+       snd = &card->capture;
+       snd->filp = filp_open(fn_cap, O_RDONLY, 0);
+       if (IS_ERR(snd->filp)) {
+               ERROR(card, "No such PCM capture device: %s\n", fn_cap);
+               snd->filp = NULL;
+       }
+       pcm_file = snd->filp->private_data;
+       snd->substream = pcm_file->substream;
+       snd->card = card;
+
+       return 0;
+}
+
+/**
+ * Close ALSA PCM and control device files
+ */
+static int gaudio_close_snd_dev(struct gaudio *gau)
+{
+       struct gaudio_snd_dev   *snd;
+
+       /* Close control device */
+       snd = &gau->control;
+       if (!IS_ERR(snd->filp))
+               filp_close(snd->filp, current->files);
+
+       /* Close PCM playback device and setup substream */
+       snd = &gau->playback;
+       if (!IS_ERR(snd->filp))
+               filp_close(snd->filp, current->files);
+
+       /* Close PCM capture device and setup substream */
+       snd = &gau->capture;
+       if (!IS_ERR(snd->filp))
+               filp_close(snd->filp, current->files);
+
+       return 0;
+}
+
+/**
+ * gaudio_setup - setup ALSA interface and preparing for USB transfer
+ *
+ * This sets up PCM, mixer or MIDI ALSA devices fore USB gadget using.
+ *
+ * Returns negative errno, or zero on success
+ */
+int __init gaudio_setup(struct gaudio *card)
+{
+       int     ret;
+
+       ret = gaudio_open_snd_dev(card);
+       if (ret)
+               ERROR(card, "we need at least one control device\n");
+
+       return ret;
+
+}
+
+/**
+ * gaudio_cleanup - remove ALSA device interface
+ *
+ * This is called to free all resources allocated by @gaudio_setup().
+ */
+void gaudio_cleanup(struct gaudio *card)
+{
+       if (card)
+               gaudio_close_snd_dev(card);
+}
+
diff --git a/drivers/usb/gadget/u_audio.h b/drivers/usb/gadget/u_audio.h
new file mode 100644 (file)
index 0000000..cc8d159
--- /dev/null
@@ -0,0 +1,56 @@
+/*
+ * u_audio.h -- interface to USB gadget "ALSA AUDIO" utilities
+ *
+ * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ * Copyright (C) 2008 Analog Devices, Inc
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef __U_AUDIO_H
+#define __U_AUDIO_H
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/composite.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "gadget_chips.h"
+
+/*
+ * This represents the USB side of an audio card device, managed by a USB
+ * function which provides control and stream interfaces.
+ */
+
+struct gaudio_snd_dev {
+       struct gaudio                   *card;
+       struct file                     *filp;
+       struct snd_pcm_substream        *substream;
+       int                             access;
+       int                             format;
+       int                             channels;
+       int                             rate;
+};
+
+struct gaudio {
+       struct usb_function             func;
+       struct usb_gadget               *gadget;
+
+       /* ALSA sound device interfaces */
+       struct gaudio_snd_dev           control;
+       struct gaudio_snd_dev           playback;
+       struct gaudio_snd_dev           capture;
+
+       /* TODO */
+};
+
+int gaudio_setup(struct gaudio *card);
+void gaudio_cleanup(struct gaudio *card);
+
+#endif /* __U_AUDIO_H */