/*
 * gmidi.c -- USB MIDI Gadget Driver
 *
 * Copyright (C) 2006 Thumtronics Pty Ltd.
 * Developed for Thumtronics by Grey Innovation
 * Ben Williamson <ben.williamson@greyinnovation.com>
 *
 * This software is distributed under the terms of the GNU General Public
 * License ("GPL") version 2, as published by the Free Software Foundation.
 *
 * This code is based in part on:
 *
 * Gadget Zero driver, Copyright (C) 2003-2004 David Brownell.
 * USB Audio driver, Copyright (C) 2002 by Takashi Iwai.
 * USB MIDI driver, Copyright (C) 2002-2005 Clemens Ladisch.
 *
 * Refer to the USB Device Class Definition for MIDI Devices:
 * http://www.usb.org/developers/devclass_docs/midi10.pdf
 */

/* #define VERBOSE_DEBUG */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/utsname.h>
#include <linux/device.h>

#include <sound/core.h>
#include <sound/initval.h>
#include <sound/rawmidi.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/audio.h>
#include <linux/usb/midi.h>

#include "gadget_chips.h"


/*
 * 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 "usbstring.c"
#include "config.c"
#include "epautoconf.c"

/*-------------------------------------------------------------------------*/


MODULE_AUTHOR("Ben Williamson");
MODULE_LICENSE("GPL v2");

#define DRIVER_VERSION "25 Jul 2006"

static const char shortname[] = "g_midi";
static const char longname[] = "MIDI Gadget";

static int index = SNDRV_DEFAULT_IDX1;
static char *id = SNDRV_DEFAULT_STR1;

module_param(index, int, 0444);
MODULE_PARM_DESC(index, "Index value for the USB MIDI Gadget adapter.");
module_param(id, charp, 0444);
MODULE_PARM_DESC(id, "ID string for the USB MIDI Gadget adapter.");

/* Some systems will want different product identifers published in the
 * device descriptor, either numbers or strings or both.  These string
 * parameters are in UTF-8 (superset of ASCII's 7 bit characters).
 */

static ushort idVendor;
module_param(idVendor, ushort, S_IRUGO);
MODULE_PARM_DESC(idVendor, "USB Vendor ID");

static ushort idProduct;
module_param(idProduct, ushort, S_IRUGO);
MODULE_PARM_DESC(idProduct, "USB Product ID");

static ushort bcdDevice;
module_param(bcdDevice, ushort, S_IRUGO);
MODULE_PARM_DESC(bcdDevice, "USB Device version (BCD)");

static char *iManufacturer;
module_param(iManufacturer, charp, S_IRUGO);
MODULE_PARM_DESC(iManufacturer, "USB Manufacturer string");

static char *iProduct;
module_param(iProduct, charp, S_IRUGO);
MODULE_PARM_DESC(iProduct, "USB Product string");

static char *iSerialNumber;
module_param(iSerialNumber, charp, S_IRUGO);
MODULE_PARM_DESC(iSerialNumber, "SerialNumber");

/*
 * this version autoconfigures as much as possible,
 * which is reasonable for most "bulk-only" drivers.
 */
static const char *EP_IN_NAME;
static const char *EP_OUT_NAME;


/* big enough to hold our biggest descriptor */
#define USB_BUFSIZ 256


/* This is a gadget, and the IN/OUT naming is from the host's perspective.
   USB -> OUT endpoint -> rawmidi
   USB <- IN endpoint  <- rawmidi */
struct gmidi_in_port {
        struct gmidi_device* dev;
        int active;
        uint8_t cable;          /* cable number << 4 */
        uint8_t state;
#define STATE_UNKNOWN   0
#define STATE_1PARAM    1
#define STATE_2PARAM_1  2
#define STATE_2PARAM_2  3
#define STATE_SYSEX_0   4
#define STATE_SYSEX_1   5
#define STATE_SYSEX_2   6
        uint8_t data[2];
};

struct gmidi_device {
        spinlock_t              lock;
        struct usb_gadget       *gadget;
        struct usb_request      *req;           /* for control responses */
        u8                      config;
        struct usb_ep           *in_ep, *out_ep;
        struct snd_card         *card;
        struct snd_rawmidi      *rmidi;
        struct snd_rawmidi_substream *in_substream;
        struct snd_rawmidi_substream *out_substream;

        /* For the moment we only support one port in
           each direction, but in_port is kept as a
           separate struct so we can have more later. */
        struct gmidi_in_port    in_port;
        unsigned long           out_triggered;
        struct tasklet_struct   tasklet;
};

static void gmidi_transmit(struct gmidi_device* dev, struct usb_request* req);


#define DBG(d, fmt, args...) \
        dev_dbg(&(d)->gadget->dev , fmt , ## args)
#define VDBG(d, fmt, args...) \
        dev_vdbg(&(d)->gadget->dev , fmt , ## args)
#define ERROR(d, fmt, args...) \
        dev_err(&(d)->gadget->dev , fmt , ## args)
#define INFO(d, fmt, args...) \
        dev_info(&(d)->gadget->dev , fmt , ## args)


static unsigned buflen = 256;
static unsigned qlen = 32;

module_param(buflen, uint, S_IRUGO);
module_param(qlen, uint, S_IRUGO);


/* Thanks to Grey Innovation for donating this product ID.
 *
 * DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!
 * Instead:  allocate your own, using normal USB-IF procedures.
 */
#define DRIVER_VENDOR_NUM       0x17b3          /* Grey Innovation */
#define DRIVER_PRODUCT_NUM      0x0004          /* Linux-USB "MIDI Gadget" */


/*
 * DESCRIPTORS ... most are static, but strings and (full)
 * configuration descriptors are built on demand.
 */

#define STRING_MANUFACTURER     25
#define STRING_PRODUCT          42
#define STRING_SERIAL           101
#define STRING_MIDI_GADGET      250

/* We only have the one configuration, it's number 1. */
#define GMIDI_CONFIG            1

/* We have two interfaces- AudioControl and MIDIStreaming */
#define GMIDI_AC_INTERFACE      0
#define GMIDI_MS_INTERFACE      1
#define GMIDI_NUM_INTERFACES    2

DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
DECLARE_USB_MS_ENDPOINT_DESCRIPTOR(1);

/* B.1  Device Descriptor */
static struct usb_device_descriptor device_desc = {
        .bLength =              USB_DT_DEVICE_SIZE,
        .bDescriptorType =      USB_DT_DEVICE,
        .bcdUSB =               cpu_to_le16(0x0200),
        .bDeviceClass =         USB_CLASS_PER_INTERFACE,
        .idVendor =             cpu_to_le16(DRIVER_VENDOR_NUM),
        .idProduct =            cpu_to_le16(DRIVER_PRODUCT_NUM),
        .iManufacturer =        STRING_MANUFACTURER,
        .iProduct =             STRING_PRODUCT,
        .bNumConfigurations =   1,
};

/* B.2  Configuration Descriptor */
static struct usb_config_descriptor config_desc = {
        .bLength =              USB_DT_CONFIG_SIZE,
        .bDescriptorType =      USB_DT_CONFIG,
        /* compute wTotalLength on the fly */
        .bNumInterfaces =       GMIDI_NUM_INTERFACES,
        .bConfigurationValue =  GMIDI_CONFIG,
        .iConfiguration =       STRING_MIDI_GADGET,
        /*
         * FIXME: When embedding this driver in a device,
         * these need to be set to reflect the actual
         * power properties of the device. Is it selfpowered?
         */
        .bmAttributes =         USB_CONFIG_ATT_ONE,
        .bMaxPower =            CONFIG_USB_GADGET_VBUS_DRAW / 2,
};

/* B.3.1  Standard AC Interface Descriptor */
static const struct usb_interface_descriptor ac_interface_desc = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        .bInterfaceNumber =     GMIDI_AC_INTERFACE,
        .bNumEndpoints =        0,
        .bInterfaceClass =      USB_CLASS_AUDIO,
        .bInterfaceSubClass =   USB_SUBCLASS_AUDIOCONTROL,
        .iInterface =           STRING_MIDI_GADGET,
};

/* B.3.2  Class-Specific AC Interface Descriptor */
static const struct uac1_ac_header_descriptor_1 ac_header_desc = {
        .bLength =              UAC_DT_AC_HEADER_SIZE(1),
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   USB_MS_HEADER,
        .bcdADC =               cpu_to_le16(0x0100),
        .wTotalLength =         cpu_to_le16(UAC_DT_AC_HEADER_SIZE(1)),
        .bInCollection =        1,
        .baInterfaceNr = {
                [0] =           GMIDI_MS_INTERFACE,
        }
};

/* B.4.1  Standard MS Interface Descriptor */
static const struct usb_interface_descriptor ms_interface_desc = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        .bInterfaceNumber =     GMIDI_MS_INTERFACE,
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_AUDIO,
        .bInterfaceSubClass =   USB_SUBCLASS_MIDISTREAMING,
        .iInterface =           STRING_MIDI_GADGET,
};

/* B.4.2  Class-Specific MS Interface Descriptor */
static const struct usb_ms_header_descriptor ms_header_desc = {
        .bLength =              USB_DT_MS_HEADER_SIZE,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   USB_MS_HEADER,
        .bcdMSC =               cpu_to_le16(0x0100),
        .wTotalLength =         cpu_to_le16(USB_DT_MS_HEADER_SIZE
                                + 2*USB_DT_MIDI_IN_SIZE
                                + 2*USB_DT_MIDI_OUT_SIZE(1)),
};

#define JACK_IN_EMB     1
#define JACK_IN_EXT     2
#define JACK_OUT_EMB    3
#define JACK_OUT_EXT    4

/* B.4.3  MIDI IN Jack Descriptors */
static const struct usb_midi_in_jack_descriptor jack_in_emb_desc = {
        .bLength =              USB_DT_MIDI_IN_SIZE,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   USB_MS_MIDI_IN_JACK,
        .bJackType =            USB_MS_EMBEDDED,
        .bJackID =              JACK_IN_EMB,
};

static const struct usb_midi_in_jack_descriptor jack_in_ext_desc = {
        .bLength =              USB_DT_MIDI_IN_SIZE,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   USB_MS_MIDI_IN_JACK,
        .bJackType =            USB_MS_EXTERNAL,
        .bJackID =              JACK_IN_EXT,
};

/* B.4.4  MIDI OUT Jack Descriptors */
static const struct usb_midi_out_jack_descriptor_1 jack_out_emb_desc = {
        .bLength =              USB_DT_MIDI_OUT_SIZE(1),
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   USB_MS_MIDI_OUT_JACK,
        .bJackType =            USB_MS_EMBEDDED,
        .bJackID =              JACK_OUT_EMB,
        .bNrInputPins =         1,
        .pins = {
                [0] = {
                        .baSourceID =   JACK_IN_EXT,
                        .baSourcePin =  1,
                }
        }
};

static const struct usb_midi_out_jack_descriptor_1 jack_out_ext_desc = {
        .bLength =              USB_DT_MIDI_OUT_SIZE(1),
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   USB_MS_MIDI_OUT_JACK,
        .bJackType =            USB_MS_EXTERNAL,
        .bJackID =              JACK_OUT_EXT,
        .bNrInputPins =         1,
        .pins = {
                [0] = {
                        .baSourceID =   JACK_IN_EMB,
                        .baSourcePin =  1,
                }
        }
};

/* B.5.1  Standard Bulk OUT Endpoint Descriptor */
static struct usb_endpoint_descriptor bulk_out_desc = {
        .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

/* B.5.2  Class-specific MS Bulk OUT Endpoint Descriptor */
static const struct usb_ms_endpoint_descriptor_1 ms_out_desc = {
        .bLength =              USB_DT_MS_ENDPOINT_SIZE(1),
        .bDescriptorType =      USB_DT_CS_ENDPOINT,
        .bDescriptorSubtype =   USB_MS_GENERAL,
        .bNumEmbMIDIJack =      1,
        .baAssocJackID = {
                [0] =           JACK_IN_EMB,
        }
};

/* B.6.1  Standard Bulk IN Endpoint Descriptor */
static struct usb_endpoint_descriptor bulk_in_desc = {
        .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

/* B.6.2  Class-specific MS Bulk IN Endpoint Descriptor */
static const struct usb_ms_endpoint_descriptor_1 ms_in_desc = {
        .bLength =              USB_DT_MS_ENDPOINT_SIZE(1),
        .bDescriptorType =      USB_DT_CS_ENDPOINT,
        .bDescriptorSubtype =   USB_MS_GENERAL,
        .bNumEmbMIDIJack =      1,
        .baAssocJackID = {
                [0] =           JACK_OUT_EMB,
        }
};

static const struct usb_descriptor_header *gmidi_function [] = {
        (struct usb_descriptor_header *)&ac_interface_desc,
        (struct usb_descriptor_header *)&ac_header_desc,
        (struct usb_descriptor_header *)&ms_interface_desc,

        (struct usb_descriptor_header *)&ms_header_desc,
        (struct usb_descriptor_header *)&jack_in_emb_desc,
        (struct usb_descriptor_header *)&jack_in_ext_desc,
        (struct usb_descriptor_header *)&jack_out_emb_desc,
        (struct usb_descriptor_header *)&jack_out_ext_desc,
        /* If you add more jacks, update ms_header_desc.wTotalLength */

        (struct usb_descriptor_header *)&bulk_out_desc,
        (struct usb_descriptor_header *)&ms_out_desc,
        (struct usb_descriptor_header *)&bulk_in_desc,
        (struct usb_descriptor_header *)&ms_in_desc,
        NULL,
};

static char manufacturer[50];
static char product_desc[40] = "MIDI Gadget";
static char serial_number[20];

/* static strings, in UTF-8 */
static struct usb_string strings [] = {
        { STRING_MANUFACTURER, manufacturer, },
        { STRING_PRODUCT, product_desc, },
        { STRING_SERIAL, serial_number, },
        { STRING_MIDI_GADGET, longname, },
        {  }                    /* end of list */
};

static struct usb_gadget_strings stringtab = {
        .language       = 0x0409,       /* en-us */
        .strings        = strings,
};

static int config_buf(struct usb_gadget *gadget,
                u8 *buf, u8 type, unsigned index)
{
        int len;

        /* only one configuration */
        if (index != 0) {
                return -EINVAL;
        }
        len = usb_gadget_config_buf(&config_desc,
                        buf, USB_BUFSIZ, gmidi_function);
        if (len < 0) {
                return len;
        }
        ((struct usb_config_descriptor *)buf)->bDescriptorType = type;
        return len;
}

static struct usb_request *alloc_ep_req(struct usb_ep *ep, unsigned length)
{
        struct usb_request      *req;

        req = usb_ep_alloc_request(ep, GFP_ATOMIC);
        if (req) {
                req->length = length;
                req->buf = kmalloc(length, GFP_ATOMIC);
                if (!req->buf) {
                        usb_ep_free_request(ep, req);
                        req = NULL;
                }
        }
        return req;
}

static void free_ep_req(struct usb_ep *ep, struct usb_request *req)
{
        kfree(req->buf);
        usb_ep_free_request(ep, req);
}

static const uint8_t gmidi_cin_length[] = {
        0, 0, 2, 3, 3, 1, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1
};

/*
 * Receives a chunk of MIDI data.
 */
static void gmidi_read_data(struct usb_ep *ep, int cable,
                                   uint8_t *data, int length)
{
        struct gmidi_device *dev = ep->driver_data;
        /* cable is ignored, because for now we only have one. */

        if (!dev->out_substream) {
                /* Nobody is listening - throw it on the floor. */
                return;
        }
        if (!test_bit(dev->out_substream->number, &dev->out_triggered)) {
                return;
        }
        snd_rawmidi_receive(dev->out_substream, data, length);
}

static void gmidi_handle_out_data(struct usb_ep *ep, struct usb_request *req)
{
        unsigned i;
        u8 *buf = req->buf;

        for (i = 0; i + 3 < req->actual; i += 4) {
                if (buf[i] != 0) {
                        int cable = buf[i] >> 4;
                        int length = gmidi_cin_length[buf[i] & 0x0f];
                        gmidi_read_data(ep, cable, &buf[i + 1], length);
                }
        }
}

static void gmidi_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct gmidi_device *dev = ep->driver_data;
        int status = req->status;

        switch (status) {
        case 0:                         /* normal completion */
                if (ep == dev->out_ep) {
                        /* we received stuff.
                           req is queued again, below */
                        gmidi_handle_out_data(ep, req);
                } else if (ep == dev->in_ep) {
                        /* our transmit completed.
                           see if there's more to go.
                           gmidi_transmit eats req, don't queue it again. */
                        gmidi_transmit(dev, req);
                        return;
                }
                break;

        /* this endpoint is normally active while we're configured */
        case -ECONNABORTED:             /* hardware forced ep reset */
        case -ECONNRESET:               /* request dequeued */
        case -ESHUTDOWN:                /* disconnect from host */
                VDBG(dev, "%s gone (%d), %d/%d\n", ep->name, status,
                                req->actual, req->length);
                if (ep == dev->out_ep) {
                        gmidi_handle_out_data(ep, req);
                }
                free_ep_req(ep, req);
                return;

        case -EOVERFLOW:                /* buffer overrun on read means that
                                         * we didn't provide a big enough
                                         * buffer.
                                         */
        default:
                DBG(dev, "%s complete --> %d, %d/%d\n", ep->name,
                                status, req->actual, req->length);
                break;
        case -EREMOTEIO:                /* short read */
                break;
        }

        status = usb_ep_queue(ep, req, GFP_ATOMIC);
        if (status) {
                ERROR(dev, "kill %s:  resubmit %d bytes --> %d\n",
                                ep->name, req->length, status);
                usb_ep_set_halt(ep);
                /* FIXME recover later ... somehow */
        }
}

static int set_gmidi_config(struct gmidi_device *dev, gfp_t gfp_flags)
{
        int err = 0;
        struct usb_request *req;
        struct usb_ep *ep;
        unsigned i;

        err = usb_ep_enable(dev->in_ep, &bulk_in_desc);
        if (err) {
                ERROR(dev, "can't start %s: %d\n", dev->in_ep->name, err);
                goto fail;
        }
        dev->in_ep->driver_data = dev;

        err = usb_ep_enable(dev->out_ep, &bulk_out_desc);
        if (err) {
                ERROR(dev, "can't start %s: %d\n", dev->out_ep->name, err);
                goto fail;
        }
        dev->out_ep->driver_data = dev;

        /* allocate a bunch of read buffers and queue them all at once. */
        ep = dev->out_ep;
        for (i = 0; i < qlen && err == 0; i++) {
                req = alloc_ep_req(ep, buflen);
                if (req) {
                        req->complete = gmidi_complete;
                        err = usb_ep_queue(ep, req, GFP_ATOMIC);
                        if (err) {
                                DBG(dev, "%s queue req: %d\n", ep->name, err);
                        }
                } else {
                        err = -ENOMEM;
                }
        }
fail:
        /* caller is responsible for cleanup on error */
        return err;
}


static void gmidi_reset_config(struct gmidi_device *dev)
{
        if (dev->config == 0) {
                return;
        }

        DBG(dev, "reset config\n");

        /* just disable endpoints, forcing completion of pending i/o.
         * all our completion handlers free their requests in this case.
         */
        usb_ep_disable(dev->in_ep);
        usb_ep_disable(dev->out_ep);
        dev->config = 0;
}

/* change our operational config.  this code must agree with the code
 * that returns config descriptors, and altsetting code.
 *
 * it's also responsible for power management interactions. some
 * configurations might not work with our current power sources.
 *
 * note that some device controller hardware will constrain what this
 * code can do, perhaps by disallowing more than one configuration or
 * by limiting configuration choices (like the pxa2xx).
 */
static int
gmidi_set_config(struct gmidi_device *dev, unsigned number, gfp_t gfp_flags)
{
        int result = 0;
        struct usb_gadget *gadget = dev->gadget;

#if 0
        /* FIXME */
        /* Hacking this bit out fixes a bug where on receipt of two
           USB_REQ_SET_CONFIGURATION messages, we end up with no
           buffered OUT requests waiting for data. This is clearly
           hiding a bug elsewhere, because if the config didn't
           change then we really shouldn't do anything. */
        /* Having said that, when we do "change" from config 1
           to config 1, we at least gmidi_reset_config() which
           clears out any requests on endpoints, so it's not like
           we leak or anything. */
        if (number == dev->config) {
                return 0;
        }
#endif

        gmidi_reset_config(dev);

        switch (number) {
        case GMIDI_CONFIG:
                result = set_gmidi_config(dev, gfp_flags);
                break;
        default:
                result = -EINVAL;
                /* FALL THROUGH */
        case 0:
                return result;
        }

        if (!result && (!dev->in_ep || !dev->out_ep)) {
                result = -ENODEV;
        }
        if (result) {
                gmidi_reset_config(dev);
        } else {
                char *speed;

                switch (gadget->speed) {
                case USB_SPEED_LOW:     speed = "low"; break;
                case USB_SPEED_FULL:    speed = "full"; break;
                case USB_SPEED_HIGH:    speed = "high"; break;
                default:                speed = "?"; break;
                }

                dev->config = number;
                INFO(dev, "%s speed\n", speed);
        }
        return result;
}


static void gmidi_setup_complete(struct usb_ep *ep, struct usb_request *req)
{
        if (req->status || req->actual != req->length) {
                DBG((struct gmidi_device *) ep->driver_data,
                                "setup complete --> %d, %d/%d\n",
                                req->status, req->actual, req->length);
        }
}

/*
 * The setup() callback implements all the ep0 functionality that's
 * not handled lower down, in hardware or the hardware driver (like
 * device and endpoint feature flags, and their status).  It's all
 * housekeeping for the gadget function we're implementing.  Most of
 * the work is in config-specific setup.
 */
static int gmidi_setup(struct usb_gadget *gadget,
                        const struct usb_ctrlrequest *ctrl)
{
        struct gmidi_device *dev = get_gadget_data(gadget);
        struct usb_request *req = dev->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);

        /* usually this stores reply data in the pre-allocated ep0 buffer,
         * but config change events will reconfigure hardware.
         */
        req->zero = 0;
        switch (ctrl->bRequest) {

        case USB_REQ_GET_DESCRIPTOR:
                if (ctrl->bRequestType != USB_DIR_IN) {
                        goto unknown;
                }
                switch (w_value >> 8) {

                case USB_DT_DEVICE:
                        value = min(w_length, (u16) sizeof(device_desc));
                        memcpy(req->buf, &device_desc, value);
                        break;
                case USB_DT_CONFIG:
                        value = config_buf(gadget, req->buf,
                                        w_value >> 8,
                                        w_value & 0xff);
                        if (value >= 0) {
                                value = min(w_length, (u16)value);
                        }
                        break;

                case USB_DT_STRING:
                        /* wIndex == language code.
                         * this driver only handles one language, you can
                         * add string tables for other languages, using
                         * any UTF-8 characters
                         */
                        value = usb_gadget_get_string(&stringtab,
                                        w_value & 0xff, req->buf);
                        if (value >= 0) {
                                value = min(w_length, (u16)value);
                        }
                        break;
                }
                break;

        /* currently two configs, two speeds */
        case USB_REQ_SET_CONFIGURATION:
                if (ctrl->bRequestType != 0) {
                        goto unknown;
                }
                if (gadget->a_hnp_support) {
                        DBG(dev, "HNP available\n");
                } else if (gadget->a_alt_hnp_support) {
                        DBG(dev, "HNP needs a different root port\n");
                } else {
                        VDBG(dev, "HNP inactive\n");
                }
                spin_lock(&dev->lock);
                value = gmidi_set_config(dev, w_value, GFP_ATOMIC);
                spin_unlock(&dev->lock);
                break;
        case USB_REQ_GET_CONFIGURATION:
                if (ctrl->bRequestType != USB_DIR_IN) {
                        goto unknown;
                }
                *(u8 *)req->buf = dev->config;
                value = min(w_length, (u16)1);
                break;

        /* until we add altsetting support, or other interfaces,
         * only 0/0 are possible.  pxa2xx only supports 0/0 (poorly)
         * and already killed pending endpoint I/O.
         */
        case USB_REQ_SET_INTERFACE:
                if (ctrl->bRequestType != USB_RECIP_INTERFACE) {
                        goto unknown;
                }
                spin_lock(&dev->lock);
                if (dev->config && w_index < GMIDI_NUM_INTERFACES
                        && w_value == 0)
                {
                        u8 config = dev->config;

                        /* resets interface configuration, forgets about
                         * previous transaction state (queued bufs, etc)
                         * and re-inits endpoint state (toggle etc)
                         * no response queued, just zero status == success.
                         * if we had more than one interface we couldn't
                         * use this "reset the config" shortcut.
                         */
                        gmidi_reset_config(dev);
                        gmidi_set_config(dev, config, GFP_ATOMIC);
                        value = 0;
                }
                spin_unlock(&dev->lock);
                break;
        case USB_REQ_GET_INTERFACE:
                if (ctrl->bRequestType != (USB_DIR_IN|USB_RECIP_INTERFACE)) {
                        goto unknown;
                }
                if (!dev->config) {
                        break;
                }
                if (w_index >= GMIDI_NUM_INTERFACES) {
                        value = -EDOM;
                        break;
                }
                *(u8 *)req->buf = 0;
                value = min(w_length, (u16)1);
                break;

        default:
unknown:
                VDBG(dev, "unknown 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 before status phase? */
        if (value >= 0) {
                req->length = value;
                req->zero = value < w_length;
                value = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
                if (value < 0) {
                        DBG(dev, "ep_queue --> %d\n", value);
                        req->status = 0;
                        gmidi_setup_complete(gadget->ep0, req);
                }
        }

        /* device either stalls (value < 0) or reports success */
        return value;
}

static void gmidi_disconnect(struct usb_gadget *gadget)
{
        struct gmidi_device *dev = get_gadget_data(gadget);
        unsigned long flags;

        spin_lock_irqsave(&dev->lock, flags);
        gmidi_reset_config(dev);

        /* a more significant application might have some non-usb
         * activities to quiesce here, saving resources like power
         * or pushing the notification up a network stack.
         */
        spin_unlock_irqrestore(&dev->lock, flags);

        /* next we may get setup() calls to enumerate new connections;
         * or an unbind() during shutdown (including removing module).
         */
}

static void /* __init_or_exit */ gmidi_unbind(struct usb_gadget *gadget)
{
        struct gmidi_device *dev = get_gadget_data(gadget);
        struct snd_card *card;

        DBG(dev, "unbind\n");

        card = dev->card;
        dev->card = NULL;
        if (card) {
                snd_card_free(card);
        }

        /* we've already been disconnected ... no i/o is active */
        if (dev->req) {
                dev->req->length = USB_BUFSIZ;
                free_ep_req(gadget->ep0, dev->req);
        }
        kfree(dev);
        set_gadget_data(gadget, NULL);
}

static int gmidi_snd_free(struct snd_device *device)
{
        return 0;
}

static void gmidi_transmit_packet(struct usb_request *req, uint8_t p0,
                                        uint8_t p1, uint8_t p2, uint8_t p3)
{
        unsigned length = req->length;
        u8 *buf = (u8 *)req->buf + length;

        buf[0] = p0;
        buf[1] = p1;
        buf[2] = p2;
        buf[3] = p3;
        req->length = length + 4;
}

/*
 * Converts MIDI commands to USB MIDI packets.
 */
static void gmidi_transmit_byte(struct usb_request *req,
                                struct gmidi_in_port *port, uint8_t b)
{
        uint8_t p0 = port->cable;

        if (b >= 0xf8) {
                gmidi_transmit_packet(req, p0 | 0x0f, b, 0, 0);
        } else if (b >= 0xf0) {
                switch (b) {
                case 0xf0:
                        port->data[0] = b;
                        port->state = STATE_SYSEX_1;
                        break;
                case 0xf1:
                case 0xf3:
                        port->data[0] = b;
                        port->state = STATE_1PARAM;
                        break;
                case 0xf2:
                        port->data[0] = b;
                        port->state = STATE_2PARAM_1;
                        break;
                case 0xf4:
                case 0xf5:
                        port->state = STATE_UNKNOWN;
                        break;
                case 0xf6:
                        gmidi_transmit_packet(req, p0 | 0x05, 0xf6, 0, 0);
                        port->state = STATE_UNKNOWN;
                        break;
                case 0xf7:
                        switch (port->state) {
                        case STATE_SYSEX_0:
                                gmidi_transmit_packet(req,
                                        p0 | 0x05, 0xf7, 0, 0);
                                break;
                        case STATE_SYSEX_1:
                                gmidi_transmit_packet(req,
                                        p0 | 0x06, port->data[0], 0xf7, 0);
                                break;
                        case STATE_SYSEX_2:
                                gmidi_transmit_packet(req,
                                        p0 | 0x07, port->data[0],
                                        port->data[1], 0xf7);
                                break;
                        }
                        port->state = STATE_UNKNOWN;
                        break;
                }
        } else if (b >= 0x80) {
                port->data[0] = b;
                if (b >= 0xc0 && b <= 0xdf)
                        port->state = STATE_1PARAM;
                else
                        port->state = STATE_2PARAM_1;
        } else { /* b < 0x80 */
                switch (port->state) {
                case STATE_1PARAM:
                        if (port->data[0] < 0xf0) {
                                p0 |= port->data[0] >> 4;
                        } else {
                                p0 |= 0x02;
                                port->state = STATE_UNKNOWN;
                        }
                        gmidi_transmit_packet(req, p0, port->data[0], b, 0);
                        break;
                case STATE_2PARAM_1:
                        port->data[1] = b;
                        port->state = STATE_2PARAM_2;
                        break;
                case STATE_2PARAM_2:
                        if (port->data[0] < 0xf0) {
                                p0 |= port->data[0] >> 4;
                                port->state = STATE_2PARAM_1;
                        } else {
                                p0 |= 0x03;
                                port->state = STATE_UNKNOWN;
                        }
                        gmidi_transmit_packet(req,
                                p0, port->data[0], port->data[1], b);
                        break;
                case STATE_SYSEX_0:
                        port->data[0] = b;
                        port->state = STATE_SYSEX_1;
                        break;
                case STATE_SYSEX_1:
                        port->data[1] = b;
                        port->state = STATE_SYSEX_2;
                        break;
                case STATE_SYSEX_2:
                        gmidi_transmit_packet(req,
                                p0 | 0x04, port->data[0], port->data[1], b);
                        port->state = STATE_SYSEX_0;
                        break;
                }
        }
}

static void gmidi_transmit(struct gmidi_device *dev, struct usb_request *req)
{
        struct usb_ep *ep = dev->in_ep;
        struct gmidi_in_port *port = &dev->in_port;

        if (!ep) {
                return;
        }
        if (!req) {
                req = alloc_ep_req(ep, buflen);
        }
        if (!req) {
                ERROR(dev, "gmidi_transmit: alloc_ep_request failed\n");
                return;
        }
        req->length = 0;
        req->complete = gmidi_complete;

        if (port->active) {
                while (req->length + 3 < buflen) {
                        uint8_t b;
                        if (snd_rawmidi_transmit(dev->in_substream, &b, 1)
                                != 1)
                        {
                                port->active = 0;
                                break;
                        }
                        gmidi_transmit_byte(req, port, b);
                }

        }
        if (req->length > 0) {
                usb_ep_queue(ep, req, GFP_ATOMIC);
        } else {
                free_ep_req(ep, req);
        }
}

static void gmidi_in_tasklet(unsigned long data)
{
        struct gmidi_device *dev = (struct gmidi_device *)data;

        gmidi_transmit(dev, NULL);
}

static int gmidi_in_open(struct snd_rawmidi_substream *substream)
{
        struct gmidi_device *dev = substream->rmidi->private_data;

        VDBG(dev, "gmidi_in_open\n");
        dev->in_substream = substream;
        dev->in_port.state = STATE_UNKNOWN;
        return 0;
}

static int gmidi_in_close(struct snd_rawmidi_substream *substream)
{
        struct gmidi_device *dev = substream->rmidi->private_data;

        VDBG(dev, "gmidi_in_close\n");
        return 0;
}

static void gmidi_in_trigger(struct snd_rawmidi_substream *substream, int up)
{
        struct gmidi_device *dev = substream->rmidi->private_data;

        VDBG(dev, "gmidi_in_trigger %d\n", up);
        dev->in_port.active = up;
        if (up) {
                tasklet_hi_schedule(&dev->tasklet);
        }
}

static int gmidi_out_open(struct snd_rawmidi_substream *substream)
{
        struct gmidi_device *dev = substream->rmidi->private_data;

        VDBG(dev, "gmidi_out_open\n");
        dev->out_substream = substream;
        return 0;
}

static int gmidi_out_close(struct snd_rawmidi_substream *substream)
{
        struct gmidi_device *dev = substream->rmidi->private_data;

        VDBG(dev, "gmidi_out_close\n");
        return 0;
}

static void gmidi_out_trigger(struct snd_rawmidi_substream *substream, int up)
{
        struct gmidi_device *dev = substream->rmidi->private_data;

        VDBG(dev, "gmidi_out_trigger %d\n", up);
        if (up) {
                set_bit(substream->number, &dev->out_triggered);
        } else {
                clear_bit(substream->number, &dev->out_triggered);
        }
}

static struct snd_rawmidi_ops gmidi_in_ops = {
        .open = gmidi_in_open,
        .close = gmidi_in_close,
        .trigger = gmidi_in_trigger,
};

static struct snd_rawmidi_ops gmidi_out_ops = {
        .open = gmidi_out_open,
        .close = gmidi_out_close,
        .trigger = gmidi_out_trigger
};

/* register as a sound "card" */
static int gmidi_register_card(struct gmidi_device *dev)
{
        struct snd_card *card;
        struct snd_rawmidi *rmidi;
        int err;
        int out_ports = 1;
        int in_ports = 1;
        static struct snd_device_ops ops = {
                .dev_free = gmidi_snd_free,
        };

        err = snd_card_create(index, id, THIS_MODULE, 0, &card);
        if (err < 0) {
                ERROR(dev, "snd_card_create failed\n");
                goto fail;
        }
        dev->card = card;

        err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, dev, &ops);
        if (err < 0) {
                ERROR(dev, "snd_device_new failed: error %d\n", err);
                goto fail;
        }

        strcpy(card->driver, longname);
        strcpy(card->longname, longname);
        strcpy(card->shortname, shortname);

        /* Set up rawmidi */
        dev->in_port.dev = dev;
        dev->in_port.active = 0;
        snd_component_add(card, "MIDI");
        err = snd_rawmidi_new(card, "USB MIDI Gadget", 0,
                              out_ports, in_ports, &rmidi);
        if (err < 0) {
                ERROR(dev, "snd_rawmidi_new failed: error %d\n", err);
                goto fail;
        }
        dev->rmidi = rmidi;
        strcpy(rmidi->name, card->shortname);
        rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
                            SNDRV_RAWMIDI_INFO_INPUT |
                            SNDRV_RAWMIDI_INFO_DUPLEX;
        rmidi->private_data = dev;

        /* Yes, rawmidi OUTPUT = USB IN, and rawmidi INPUT = USB OUT.
           It's an upside-down world being a gadget. */
        snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &gmidi_in_ops);
        snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &gmidi_out_ops);

        snd_card_set_dev(card, &dev->gadget->dev);

        /* register it - we're ready to go */
        err = snd_card_register(card);
        if (err < 0) {
                ERROR(dev, "snd_card_register failed\n");
                goto fail;
        }

        VDBG(dev, "gmidi_register_card finished ok\n");
        return 0;

fail:
        if (dev->card) {
                snd_card_free(dev->card);
                dev->card = NULL;
        }
        return err;
}

/*
 * Creates an output endpoint, and initializes output ports.
 */
static int __init gmidi_bind(struct usb_gadget *gadget)
{
        struct gmidi_device *dev;
        struct usb_ep *in_ep, *out_ep;
        int gcnum, err = 0;

        /* support optional vendor/distro customization */
        if (idVendor) {
                if (!idProduct) {
                        pr_err("idVendor needs idProduct!\n");
                        return -ENODEV;
                }
                device_desc.idVendor = cpu_to_le16(idVendor);
                device_desc.idProduct = cpu_to_le16(idProduct);
                if (bcdDevice) {
                        device_desc.bcdDevice = cpu_to_le16(bcdDevice);
                }
        }
        if (iManufacturer) {
                strlcpy(manufacturer, iManufacturer, sizeof(manufacturer));
        } else {
                snprintf(manufacturer, sizeof(manufacturer), "%s %s with %s",
                        init_utsname()->sysname, init_utsname()->release,
                        gadget->name);
        }
        if (iProduct) {
                strlcpy(product_desc, iProduct, sizeof(product_desc));
        }
        if (iSerialNumber) {
                device_desc.iSerialNumber = STRING_SERIAL,
                strlcpy(serial_number, iSerialNumber, sizeof(serial_number));
        }

        /* Bulk-only drivers like this one SHOULD be able to
         * autoconfigure on any sane usb controller driver,
         * but there may also be important quirks to address.
         */
        usb_ep_autoconfig_reset(gadget);
        in_ep = usb_ep_autoconfig(gadget, &bulk_in_desc);
        if (!in_ep) {
autoconf_fail:
                pr_err("%s: can't autoconfigure on %s\n",
                        shortname, gadget->name);
                return -ENODEV;
        }
        EP_IN_NAME = in_ep->name;
        in_ep->driver_data = in_ep;     /* claim */

        out_ep = usb_ep_autoconfig(gadget, &bulk_out_desc);
        if (!out_ep) {
                goto autoconf_fail;
        }
        EP_OUT_NAME = out_ep->name;
        out_ep->driver_data = out_ep;   /* claim */

        gcnum = usb_gadget_controller_number(gadget);
        if (gcnum >= 0) {
                device_desc.bcdDevice = cpu_to_le16(0x0200 + gcnum);
        } else {
                /* gmidi is so simple (no altsettings) that
                 * it SHOULD NOT have problems with bulk-capable hardware.
                 * so warn about unrecognized controllers, don't panic.
                 */
                pr_warning("%s: controller '%s' not recognized\n",
                        shortname, gadget->name);
                device_desc.bcdDevice = cpu_to_le16(0x9999);
        }


        /* ok, we made sense of the hardware ... */
        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev) {
                return -ENOMEM;
        }
        spin_lock_init(&dev->lock);
        dev->gadget = gadget;
        dev->in_ep = in_ep;
        dev->out_ep = out_ep;
        set_gadget_data(gadget, dev);
        tasklet_init(&dev->tasklet, gmidi_in_tasklet, (unsigned long)dev);

        /* preallocate control response and buffer */
        dev->req = alloc_ep_req(gadget->ep0, USB_BUFSIZ);
        if (!dev->req) {
                err = -ENOMEM;
                goto fail;
        }

        dev->req->complete = gmidi_setup_complete;

        device_desc.bMaxPacketSize0 = gadget->ep0->maxpacket;

        gadget->ep0->driver_data = dev;

        INFO(dev, "%s, version: " DRIVER_VERSION "\n", longname);
        INFO(dev, "using %s, OUT %s IN %s\n", gadget->name,
                EP_OUT_NAME, EP_IN_NAME);

        /* register as an ALSA sound card */
        err = gmidi_register_card(dev);
        if (err < 0) {
                goto fail;
        }

        VDBG(dev, "gmidi_bind finished ok\n");
        return 0;

fail:
        gmidi_unbind(gadget);
        return err;
}


static void gmidi_suspend(struct usb_gadget *gadget)
{
        struct gmidi_device *dev = get_gadget_data(gadget);

        if (gadget->speed == USB_SPEED_UNKNOWN) {
                return;
        }

        DBG(dev, "suspend\n");
}

static void gmidi_resume(struct usb_gadget *gadget)
{
        struct gmidi_device *dev = get_gadget_data(gadget);

        DBG(dev, "resume\n");
}


static struct usb_gadget_driver gmidi_driver = {
        .speed          = USB_SPEED_FULL,
        .function       = (char *)longname,
        .unbind         = gmidi_unbind,

        .setup          = gmidi_setup,
        .disconnect     = gmidi_disconnect,

        .suspend        = gmidi_suspend,
        .resume         = gmidi_resume,

        .driver         = {
                .name           = (char *)shortname,
                .owner          = THIS_MODULE,
        },
};

static int __init gmidi_init(void)
{
        return usb_gadget_probe_driver(&gmidi_driver, gmidi_bind);
}
module_init(gmidi_init);

static void __exit gmidi_cleanup(void)
{
        usb_gadget_unregister_driver(&gmidi_driver);
}
module_exit(gmidi_cleanup);