/*
 * f_sourcesink.c - USB peripheral source/sink configuration driver
 *
 * Copyright (C) 2003-2008 David Brownell
 * Copyright (C) 2008 by Nokia Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

/* #define VERBOSE_DEBUG */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/usb/composite.h>
#include <linux/err.h>

#include "g_zero.h"
#include "u_f.h"

/*
 * SOURCE/SINK FUNCTION ... a primary testing vehicle for USB peripheral
 * controller drivers.
 *
 * This just sinks bulk packets OUT to the peripheral and sources them IN
 * to the host, optionally with specific data patterns for integrity tests.
 * As such it supports basic functionality and load tests.
 *
 * In terms of control messaging, this supports all the standard requests
 * plus two that support control-OUT tests.  If the optional "autoresume"
 * mode is enabled, it provides good functional coverage for the "USBCV"
 * test harness from USB-IF.
 */
struct f_sourcesink {
        struct usb_function     function;

        struct usb_ep           *in_ep;
        struct usb_ep           *out_ep;
        struct usb_ep           *iso_in_ep;
        struct usb_ep           *iso_out_ep;
        int                     cur_alt;

        unsigned pattern;
        unsigned isoc_interval;
        unsigned isoc_maxpacket;
        unsigned isoc_mult;
        unsigned isoc_maxburst;
        unsigned buflen;
        unsigned bulk_qlen;
        unsigned iso_qlen;
};

static inline struct f_sourcesink *func_to_ss(struct usb_function *f)
{
        return container_of(f, struct f_sourcesink, function);
}

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

static struct usb_interface_descriptor source_sink_intf_alt0 = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,

        .bAlternateSetting =    0,
        .bNumEndpoints =        2,
        .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
        /* .iInterface          = DYNAMIC */
};

static struct usb_interface_descriptor source_sink_intf_alt1 = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,

        .bAlternateSetting =    1,
        .bNumEndpoints =        4,
        .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
        /* .iInterface          = DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor fs_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor fs_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor fs_iso_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_IN,
        .bmAttributes =         USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(1023),
        .bInterval =            4,
};

static struct usb_endpoint_descriptor fs_iso_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(1023),
        .bInterval =            4,
};

static struct usb_descriptor_header *fs_source_sink_descs[] = {
        (struct usb_descriptor_header *) &source_sink_intf_alt0,
        (struct usb_descriptor_header *) &fs_sink_desc,
        (struct usb_descriptor_header *) &fs_source_desc,
        (struct usb_descriptor_header *) &source_sink_intf_alt1,
#define FS_ALT_IFC_1_OFFSET     3
        (struct usb_descriptor_header *) &fs_sink_desc,
        (struct usb_descriptor_header *) &fs_source_desc,
        (struct usb_descriptor_header *) &fs_iso_sink_desc,
        (struct usb_descriptor_header *) &fs_iso_source_desc,
        NULL,
};

/* high speed support: */

static struct usb_endpoint_descriptor hs_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_endpoint_descriptor hs_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(512),
};

static struct usb_endpoint_descriptor hs_iso_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(1024),
        .bInterval =            4,
};

static struct usb_endpoint_descriptor hs_iso_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(1024),
        .bInterval =            4,
};

static struct usb_descriptor_header *hs_source_sink_descs[] = {
        (struct usb_descriptor_header *) &source_sink_intf_alt0,
        (struct usb_descriptor_header *) &hs_source_desc,
        (struct usb_descriptor_header *) &hs_sink_desc,
        (struct usb_descriptor_header *) &source_sink_intf_alt1,
#define HS_ALT_IFC_1_OFFSET     3
        (struct usb_descriptor_header *) &hs_source_desc,
        (struct usb_descriptor_header *) &hs_sink_desc,
        (struct usb_descriptor_header *) &hs_iso_source_desc,
        (struct usb_descriptor_header *) &hs_iso_sink_desc,
        NULL,
};

/* super speed support: */

static struct usb_endpoint_descriptor ss_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor ss_source_comp_desc = {
        .bLength =              USB_DT_SS_EP_COMP_SIZE,
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,

        .bMaxBurst =            0,
        .bmAttributes =         0,
        .wBytesPerInterval =    0,
};

static struct usb_endpoint_descriptor ss_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
        .wMaxPacketSize =       cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor ss_sink_comp_desc = {
        .bLength =              USB_DT_SS_EP_COMP_SIZE,
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,

        .bMaxBurst =            0,
        .bmAttributes =         0,
        .wBytesPerInterval =    0,
};

static struct usb_endpoint_descriptor ss_iso_source_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(1024),
        .bInterval =            4,
};

static struct usb_ss_ep_comp_descriptor ss_iso_source_comp_desc = {
        .bLength =              USB_DT_SS_EP_COMP_SIZE,
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,

        .bMaxBurst =            0,
        .bmAttributes =         0,
        .wBytesPerInterval =    cpu_to_le16(1024),
};

static struct usb_endpoint_descriptor ss_iso_sink_desc = {
        .bLength =              USB_DT_ENDPOINT_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,

        .bmAttributes =         USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(1024),
        .bInterval =            4,
};

static struct usb_ss_ep_comp_descriptor ss_iso_sink_comp_desc = {
        .bLength =              USB_DT_SS_EP_COMP_SIZE,
        .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,

        .bMaxBurst =            0,
        .bmAttributes =         0,
        .wBytesPerInterval =    cpu_to_le16(1024),
};

static struct usb_descriptor_header *ss_source_sink_descs[] = {
        (struct usb_descriptor_header *) &source_sink_intf_alt0,
        (struct usb_descriptor_header *) &ss_source_desc,
        (struct usb_descriptor_header *) &ss_source_comp_desc,
        (struct usb_descriptor_header *) &ss_sink_desc,
        (struct usb_descriptor_header *) &ss_sink_comp_desc,
        (struct usb_descriptor_header *) &source_sink_intf_alt1,
#define SS_ALT_IFC_1_OFFSET     5
        (struct usb_descriptor_header *) &ss_source_desc,
        (struct usb_descriptor_header *) &ss_source_comp_desc,
        (struct usb_descriptor_header *) &ss_sink_desc,
        (struct usb_descriptor_header *) &ss_sink_comp_desc,
        (struct usb_descriptor_header *) &ss_iso_source_desc,
        (struct usb_descriptor_header *) &ss_iso_source_comp_desc,
        (struct usb_descriptor_header *) &ss_iso_sink_desc,
        (struct usb_descriptor_header *) &ss_iso_sink_comp_desc,
        NULL,
};

/* function-specific strings: */

static struct usb_string strings_sourcesink[] = {
        [0].s = "source and sink data",
        {  }                    /* end of list */
};

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

static struct usb_gadget_strings *sourcesink_strings[] = {
        &stringtab_sourcesink,
        NULL,
};

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

static inline struct usb_request *ss_alloc_ep_req(struct usb_ep *ep, int len)
{
        struct f_sourcesink             *ss = ep->driver_data;

        return alloc_ep_req(ep, len, ss->buflen);
}

static void disable_ep(struct usb_composite_dev *cdev, struct usb_ep *ep)
{
        int                     value;

        value = usb_ep_disable(ep);
        if (value < 0)
                DBG(cdev, "disable %s --> %d\n", ep->name, value);
}

void disable_endpoints(struct usb_composite_dev *cdev,
                struct usb_ep *in, struct usb_ep *out,
                struct usb_ep *iso_in, struct usb_ep *iso_out)
{
        disable_ep(cdev, in);
        disable_ep(cdev, out);
        if (iso_in)
                disable_ep(cdev, iso_in);
        if (iso_out)
                disable_ep(cdev, iso_out);
}

static int
sourcesink_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct f_sourcesink     *ss = func_to_ss(f);
        int     id;
        int ret;

        /* allocate interface ID(s) */
        id = usb_interface_id(c, f);
        if (id < 0)
                return id;
        source_sink_intf_alt0.bInterfaceNumber = id;
        source_sink_intf_alt1.bInterfaceNumber = id;

        /* allocate bulk endpoints */
        ss->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_source_desc);
        if (!ss->in_ep) {
autoconf_fail:
                ERROR(cdev, "%s: can't autoconfigure on %s\n",
                        f->name, cdev->gadget->name);
                return -ENODEV;
        }

        ss->out_ep = usb_ep_autoconfig(cdev->gadget, &fs_sink_desc);
        if (!ss->out_ep)
                goto autoconf_fail;

        /* sanity check the isoc module parameters */
        if (ss->isoc_interval < 1)
                ss->isoc_interval = 1;
        if (ss->isoc_interval > 16)
                ss->isoc_interval = 16;
        if (ss->isoc_mult > 2)
                ss->isoc_mult = 2;
        if (ss->isoc_maxburst > 15)
                ss->isoc_maxburst = 15;

        /* fill in the FS isoc descriptors from the module parameters */
        fs_iso_source_desc.wMaxPacketSize = ss->isoc_maxpacket > 1023 ?
                                                1023 : ss->isoc_maxpacket;
        fs_iso_source_desc.bInterval = ss->isoc_interval;
        fs_iso_sink_desc.wMaxPacketSize = ss->isoc_maxpacket > 1023 ?
                                                1023 : ss->isoc_maxpacket;
        fs_iso_sink_desc.bInterval = ss->isoc_interval;

        /* allocate iso endpoints */
        ss->iso_in_ep = usb_ep_autoconfig(cdev->gadget, &fs_iso_source_desc);
        if (!ss->iso_in_ep)
                goto no_iso;

        ss->iso_out_ep = usb_ep_autoconfig(cdev->gadget, &fs_iso_sink_desc);
        if (!ss->iso_out_ep) {
                usb_ep_autoconfig_release(ss->iso_in_ep);
                ss->iso_in_ep = NULL;
no_iso:
                /*
                 * We still want to work even if the UDC doesn't have isoc
                 * endpoints, so null out the alt interface that contains
                 * them and continue.
                 */
                fs_source_sink_descs[FS_ALT_IFC_1_OFFSET] = NULL;
                hs_source_sink_descs[HS_ALT_IFC_1_OFFSET] = NULL;
                ss_source_sink_descs[SS_ALT_IFC_1_OFFSET] = NULL;
        }

        if (ss->isoc_maxpacket > 1024)
                ss->isoc_maxpacket = 1024;

        /* support high speed hardware */
        hs_source_desc.bEndpointAddress = fs_source_desc.bEndpointAddress;
        hs_sink_desc.bEndpointAddress = fs_sink_desc.bEndpointAddress;

        /*
         * Fill in the HS isoc descriptors from the module parameters.
         * We assume that the user knows what they are doing and won't
         * give parameters that their UDC doesn't support.
         */
        hs_iso_source_desc.wMaxPacketSize = ss->isoc_maxpacket;
        hs_iso_source_desc.wMaxPacketSize |= ss->isoc_mult << 11;
        hs_iso_source_desc.bInterval = ss->isoc_interval;
        hs_iso_source_desc.bEndpointAddress =
                fs_iso_source_desc.bEndpointAddress;

        hs_iso_sink_desc.wMaxPacketSize = ss->isoc_maxpacket;
        hs_iso_sink_desc.wMaxPacketSize |= ss->isoc_mult << 11;
        hs_iso_sink_desc.bInterval = ss->isoc_interval;
        hs_iso_sink_desc.bEndpointAddress = fs_iso_sink_desc.bEndpointAddress;

        /* support super speed hardware */
        ss_source_desc.bEndpointAddress =
                fs_source_desc.bEndpointAddress;
        ss_sink_desc.bEndpointAddress =
                fs_sink_desc.bEndpointAddress;

        /*
         * Fill in the SS isoc descriptors from the module parameters.
         * We assume that the user knows what they are doing and won't
         * give parameters that their UDC doesn't support.
         */
        ss_iso_source_desc.wMaxPacketSize = ss->isoc_maxpacket;
        ss_iso_source_desc.bInterval = ss->isoc_interval;
        ss_iso_source_comp_desc.bmAttributes = ss->isoc_mult;
        ss_iso_source_comp_desc.bMaxBurst = ss->isoc_maxburst;
        ss_iso_source_comp_desc.wBytesPerInterval = ss->isoc_maxpacket *
                (ss->isoc_mult + 1) * (ss->isoc_maxburst + 1);
        ss_iso_source_desc.bEndpointAddress =
                fs_iso_source_desc.bEndpointAddress;

        ss_iso_sink_desc.wMaxPacketSize = ss->isoc_maxpacket;
        ss_iso_sink_desc.bInterval = ss->isoc_interval;
        ss_iso_sink_comp_desc.bmAttributes = ss->isoc_mult;
        ss_iso_sink_comp_desc.bMaxBurst = ss->isoc_maxburst;
        ss_iso_sink_comp_desc.wBytesPerInterval = ss->isoc_maxpacket *
                (ss->isoc_mult + 1) * (ss->isoc_maxburst + 1);
        ss_iso_sink_desc.bEndpointAddress = fs_iso_sink_desc.bEndpointAddress;

        ret = usb_assign_descriptors(f, fs_source_sink_descs,
                        hs_source_sink_descs, ss_source_sink_descs);
        if (ret)
                return ret;

        DBG(cdev, "%s speed %s: IN/%s, OUT/%s, ISO-IN/%s, ISO-OUT/%s\n",
            (gadget_is_superspeed(c->cdev->gadget) ? "super" :
             (gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full")),
                        f->name, ss->in_ep->name, ss->out_ep->name,
                        ss->iso_in_ep ? ss->iso_in_ep->name : "<none>",
                        ss->iso_out_ep ? ss->iso_out_ep->name : "<none>");
        return 0;
}

static void
sourcesink_free_func(struct usb_function *f)
{
        struct f_ss_opts *opts;

        opts = container_of(f->fi, struct f_ss_opts, func_inst);

        mutex_lock(&opts->lock);
        opts->refcnt--;
        mutex_unlock(&opts->lock);

        usb_free_all_descriptors(f);
        kfree(func_to_ss(f));
}

/* optionally require specific source/sink data patterns  */
static int check_read_data(struct f_sourcesink *ss, struct usb_request *req)
{
        unsigned                i;
        u8                      *buf = req->buf;
        struct usb_composite_dev *cdev = ss->function.config->cdev;
        int max_packet_size = le16_to_cpu(ss->out_ep->desc->wMaxPacketSize);

        if (ss->pattern == 2)
                return 0;

        for (i = 0; i < req->actual; i++, buf++) {
                switch (ss->pattern) {

                /* all-zeroes has no synchronization issues */
                case 0:
                        if (*buf == 0)
                                continue;
                        break;

                /* "mod63" stays in sync with short-terminated transfers,
                 * OR otherwise when host and gadget agree on how large
                 * each usb transfer request should be.  Resync is done
                 * with set_interface or set_config.  (We *WANT* it to
                 * get quickly out of sync if controllers or their drivers
                 * stutter for any reason, including buffer duplication...)
                 */
                case 1:
                        if (*buf == (u8)((i % max_packet_size) % 63))
                                continue;
                        break;
                }
                ERROR(cdev, "bad OUT byte, buf[%d] = %d\n", i, *buf);
                usb_ep_set_halt(ss->out_ep);
                return -EINVAL;
        }
        return 0;
}

static void reinit_write_data(struct usb_ep *ep, struct usb_request *req)
{
        unsigned        i;
        u8              *buf = req->buf;
        int max_packet_size = le16_to_cpu(ep->desc->wMaxPacketSize);
        struct f_sourcesink *ss = ep->driver_data;

        switch (ss->pattern) {
        case 0:
                memset(req->buf, 0, req->length);
                break;
        case 1:
                for  (i = 0; i < req->length; i++)
                        *buf++ = (u8) ((i % max_packet_size) % 63);
                break;
        case 2:
                break;
        }
}

static void source_sink_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct usb_composite_dev        *cdev;
        struct f_sourcesink             *ss = ep->driver_data;
        int                             status = req->status;

        /* driver_data will be null if ep has been disabled */
        if (!ss)
                return;

        cdev = ss->function.config->cdev;

        switch (status) {

        case 0:                         /* normal completion? */
                if (ep == ss->out_ep) {
                        check_read_data(ss, req);
                        if (ss->pattern != 2)
                                memset(req->buf, 0x55, req->length);
                }
                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(cdev, "%s gone (%d), %d/%d\n", ep->name, status,
                                req->actual, req->length);
                if (ep == ss->out_ep)
                        check_read_data(ss, req);
                free_ep_req(ep, req);
                return;

        case -EOVERFLOW:                /* buffer overrun on read means that
                                         * we didn't provide a big enough
                                         * buffer.
                                         */
        default:
#if 1
                DBG(cdev, "%s complete --> %d, %d/%d\n", ep->name,
                                status, req->actual, req->length);
#endif
        case -EREMOTEIO:                /* short read */
                break;
        }

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

static int source_sink_start_ep(struct f_sourcesink *ss, bool is_in,
                bool is_iso, int speed)
{
        struct usb_ep           *ep;
        struct usb_request      *req;
        int                     i, size, qlen, status = 0;

        if (is_iso) {
                switch (speed) {
                case USB_SPEED_SUPER:
                        size = ss->isoc_maxpacket *
                                        (ss->isoc_mult + 1) *
                                        (ss->isoc_maxburst + 1);
                        break;
                case USB_SPEED_HIGH:
                        size = ss->isoc_maxpacket * (ss->isoc_mult + 1);
                        break;
                default:
                        size = ss->isoc_maxpacket > 1023 ?
                                        1023 : ss->isoc_maxpacket;
                        break;
                }
                ep = is_in ? ss->iso_in_ep : ss->iso_out_ep;
                qlen = ss->iso_qlen;
        } else {
                ep = is_in ? ss->in_ep : ss->out_ep;
                qlen = ss->bulk_qlen;
                size = 0;
        }

        for (i = 0; i < qlen; i++) {
                req = ss_alloc_ep_req(ep, size);
                if (!req)
                        return -ENOMEM;

                req->complete = source_sink_complete;
                if (is_in)
                        reinit_write_data(ep, req);
                else if (ss->pattern != 2)
                        memset(req->buf, 0x55, req->length);

                status = usb_ep_queue(ep, req, GFP_ATOMIC);
                if (status) {
                        struct usb_composite_dev        *cdev;

                        cdev = ss->function.config->cdev;
                        ERROR(cdev, "start %s%s %s --> %d\n",
                              is_iso ? "ISO-" : "", is_in ? "IN" : "OUT",
                              ep->name, status);
                        free_ep_req(ep, req);
                        return status;
                }
        }

        return status;
}

static void disable_source_sink(struct f_sourcesink *ss)
{
        struct usb_composite_dev        *cdev;

        cdev = ss->function.config->cdev;
        disable_endpoints(cdev, ss->in_ep, ss->out_ep, ss->iso_in_ep,
                        ss->iso_out_ep);
        VDBG(cdev, "%s disabled\n", ss->function.name);
}

static int
enable_source_sink(struct usb_composite_dev *cdev, struct f_sourcesink *ss,
                int alt)
{
        int                                     result = 0;
        int                                     speed = cdev->gadget->speed;
        struct usb_ep                           *ep;

        /* one bulk endpoint writes (sources) zeroes IN (to the host) */
        ep = ss->in_ep;
        result = config_ep_by_speed(cdev->gadget, &(ss->function), ep);
        if (result)
                return result;
        result = usb_ep_enable(ep);
        if (result < 0)
                return result;
        ep->driver_data = ss;

        result = source_sink_start_ep(ss, true, false, speed);
        if (result < 0) {
fail:
                ep = ss->in_ep;
                usb_ep_disable(ep);
                return result;
        }

        /* one bulk endpoint reads (sinks) anything OUT (from the host) */
        ep = ss->out_ep;
        result = config_ep_by_speed(cdev->gadget, &(ss->function), ep);
        if (result)
                goto fail;
        result = usb_ep_enable(ep);
        if (result < 0)
                goto fail;
        ep->driver_data = ss;

        result = source_sink_start_ep(ss, false, false, speed);
        if (result < 0) {
fail2:
                ep = ss->out_ep;
                usb_ep_disable(ep);
                goto fail;
        }

        if (alt == 0)
                goto out;

        /* one iso endpoint writes (sources) zeroes IN (to the host) */
        ep = ss->iso_in_ep;
        if (ep) {
                result = config_ep_by_speed(cdev->gadget, &(ss->function), ep);
                if (result)
                        goto fail2;
                result = usb_ep_enable(ep);
                if (result < 0)
                        goto fail2;
                ep->driver_data = ss;

                result = source_sink_start_ep(ss, true, true, speed);
                if (result < 0) {
fail3:
                        ep = ss->iso_in_ep;
                        if (ep)
                                usb_ep_disable(ep);
                        goto fail2;
                }
        }

        /* one iso endpoint reads (sinks) anything OUT (from the host) */
        ep = ss->iso_out_ep;
        if (ep) {
                result = config_ep_by_speed(cdev->gadget, &(ss->function), ep);
                if (result)
                        goto fail3;
                result = usb_ep_enable(ep);
                if (result < 0)
                        goto fail3;
                ep->driver_data = ss;

                result = source_sink_start_ep(ss, false, true, speed);
                if (result < 0) {
                        usb_ep_disable(ep);
                        goto fail3;
                }
        }
out:
        ss->cur_alt = alt;

        DBG(cdev, "%s enabled, alt intf %d\n", ss->function.name, alt);
        return result;
}

static int sourcesink_set_alt(struct usb_function *f,
                unsigned intf, unsigned alt)
{
        struct f_sourcesink             *ss = func_to_ss(f);
        struct usb_composite_dev        *cdev = f->config->cdev;

        disable_source_sink(ss);
        return enable_source_sink(cdev, ss, alt);
}

static int sourcesink_get_alt(struct usb_function *f, unsigned intf)
{
        struct f_sourcesink             *ss = func_to_ss(f);

        return ss->cur_alt;
}

static void sourcesink_disable(struct usb_function *f)
{
        struct f_sourcesink     *ss = func_to_ss(f);

        disable_source_sink(ss);
}

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

static int sourcesink_setup(struct usb_function *f,
                const struct usb_ctrlrequest *ctrl)
{
        struct usb_configuration        *c = f->config;
        struct usb_request      *req = c->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);

        req->length = USB_COMP_EP0_BUFSIZ;

        /* composite driver infrastructure handles everything except
         * the two control test requests.
         */
        switch (ctrl->bRequest) {

        /*
         * These are the same vendor-specific requests supported by
         * Intel's USB 2.0 compliance test devices.  We exceed that
         * device spec by allowing multiple-packet requests.
         *
         * NOTE:  the Control-OUT data stays in req->buf ... better
         * would be copying it into a scratch buffer, so that other
         * requests may safely intervene.
         */
        case 0x5b:      /* control WRITE test -- fill the buffer */
                if (ctrl->bRequestType != (USB_DIR_OUT|USB_TYPE_VENDOR))
                        goto unknown;
                if (w_value || w_index)
                        break;
                /* just read that many bytes into the buffer */
                if (w_length > req->length)
                        break;
                value = w_length;
                break;
        case 0x5c:      /* control READ test -- return the buffer */
                if (ctrl->bRequestType != (USB_DIR_IN|USB_TYPE_VENDOR))
                        goto unknown;
                if (w_value || w_index)
                        break;
                /* expect those bytes are still in the buffer; send back */
                if (w_length > req->length)
                        break;
                value = w_length;
                break;

        default:
unknown:
                VDBG(c->cdev,
                        "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 or status phase? */
        if (value >= 0) {
                VDBG(c->cdev, "source/sink 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(c->cdev->gadget->ep0, req, GFP_ATOMIC);
                if (value < 0)
                        ERROR(c->cdev, "source/sink response, err %d\n",
                                        value);
        }

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

static struct usb_function *source_sink_alloc_func(
                struct usb_function_instance *fi)
{
        struct f_sourcesink     *ss;
        struct f_ss_opts        *ss_opts;

        ss = kzalloc(sizeof(*ss), GFP_KERNEL);
        if (!ss)
                return NULL;

        ss_opts =  container_of(fi, struct f_ss_opts, func_inst);

        mutex_lock(&ss_opts->lock);
        ss_opts->refcnt++;
        mutex_unlock(&ss_opts->lock);

        ss->pattern = ss_opts->pattern;
        ss->isoc_interval = ss_opts->isoc_interval;
        ss->isoc_maxpacket = ss_opts->isoc_maxpacket;
        ss->isoc_mult = ss_opts->isoc_mult;
        ss->isoc_maxburst = ss_opts->isoc_maxburst;
        ss->buflen = ss_opts->bulk_buflen;
        ss->bulk_qlen = ss_opts->bulk_qlen;
        ss->iso_qlen = ss_opts->iso_qlen;

        ss->function.name = "source/sink";
        ss->function.bind = sourcesink_bind;
        ss->function.set_alt = sourcesink_set_alt;
        ss->function.get_alt = sourcesink_get_alt;
        ss->function.disable = sourcesink_disable;
        ss->function.setup = sourcesink_setup;
        ss->function.strings = sourcesink_strings;

        ss->function.free_func = sourcesink_free_func;

        return &ss->function;
}

static inline struct f_ss_opts *to_f_ss_opts(struct config_item *item)
{
        return container_of(to_config_group(item), struct f_ss_opts,
                            func_inst.group);
}

static void ss_attr_release(struct config_item *item)
{
        struct f_ss_opts *ss_opts = to_f_ss_opts(item);

        usb_put_function_instance(&ss_opts->func_inst);
}

static struct configfs_item_operations ss_item_ops = {
        .release                = ss_attr_release,
};

static ssize_t f_ss_opts_pattern_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->pattern);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_pattern_store(struct config_item *item,
                                       const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u8 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou8(page, 0, &num);
        if (ret)
                goto end;

        if (num != 0 && num != 1 && num != 2) {
                ret = -EINVAL;
                goto end;
        }

        opts->pattern = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, pattern);

static ssize_t f_ss_opts_isoc_interval_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->isoc_interval);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_isoc_interval_store(struct config_item *item,
                                       const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u8 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou8(page, 0, &num);
        if (ret)
                goto end;

        if (num > 16) {
                ret = -EINVAL;
                goto end;
        }

        opts->isoc_interval = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, isoc_interval);

static ssize_t f_ss_opts_isoc_maxpacket_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->isoc_maxpacket);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_isoc_maxpacket_store(struct config_item *item,
                                       const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u16 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {

                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou16(page, 0, &num);
        if (ret)
                goto end;

        if (num > 1024) {
                ret = -EINVAL;
                goto end;
        }

        opts->isoc_maxpacket = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, isoc_maxpacket);

static ssize_t f_ss_opts_isoc_mult_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->isoc_mult);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_isoc_mult_store(struct config_item *item,
                                       const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u8 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou8(page, 0, &num);
        if (ret)
                goto end;

        if (num > 2) {
                ret = -EINVAL;
                goto end;
        }

        opts->isoc_mult = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, isoc_mult);

static ssize_t f_ss_opts_isoc_maxburst_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->isoc_maxburst);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_isoc_maxburst_store(struct config_item *item,
                                       const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u8 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou8(page, 0, &num);
        if (ret)
                goto end;

        if (num > 15) {
                ret = -EINVAL;
                goto end;
        }

        opts->isoc_maxburst = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, isoc_maxburst);

static ssize_t f_ss_opts_bulk_buflen_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->bulk_buflen);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_bulk_buflen_store(struct config_item *item,
                                           const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u32 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou32(page, 0, &num);
        if (ret)
                goto end;

        opts->bulk_buflen = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, bulk_buflen);

static ssize_t f_ss_opts_bulk_qlen_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->bulk_qlen);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_bulk_qlen_store(struct config_item *item,
                                           const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u32 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou32(page, 0, &num);
        if (ret)
                goto end;

        opts->bulk_qlen = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, bulk_qlen);

static ssize_t f_ss_opts_iso_qlen_show(struct config_item *item, char *page)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int result;

        mutex_lock(&opts->lock);
        result = sprintf(page, "%u\n", opts->iso_qlen);
        mutex_unlock(&opts->lock);

        return result;
}

static ssize_t f_ss_opts_iso_qlen_store(struct config_item *item,
                                           const char *page, size_t len)
{
        struct f_ss_opts *opts = to_f_ss_opts(item);
        int ret;
        u32 num;

        mutex_lock(&opts->lock);
        if (opts->refcnt) {
                ret = -EBUSY;
                goto end;
        }

        ret = kstrtou32(page, 0, &num);
        if (ret)
                goto end;

        opts->iso_qlen = num;
        ret = len;
end:
        mutex_unlock(&opts->lock);
        return ret;
}

CONFIGFS_ATTR(f_ss_opts_, iso_qlen);

static struct configfs_attribute *ss_attrs[] = {
        &f_ss_opts_attr_pattern,
        &f_ss_opts_attr_isoc_interval,
        &f_ss_opts_attr_isoc_maxpacket,
        &f_ss_opts_attr_isoc_mult,
        &f_ss_opts_attr_isoc_maxburst,
        &f_ss_opts_attr_bulk_buflen,
        &f_ss_opts_attr_bulk_qlen,
        &f_ss_opts_attr_iso_qlen,
        NULL,
};

static struct config_item_type ss_func_type = {
        .ct_item_ops    = &ss_item_ops,
        .ct_attrs       = ss_attrs,
        .ct_owner       = THIS_MODULE,
};

static void source_sink_free_instance(struct usb_function_instance *fi)
{
        struct f_ss_opts *ss_opts;

        ss_opts = container_of(fi, struct f_ss_opts, func_inst);
        kfree(ss_opts);
}

static struct usb_function_instance *source_sink_alloc_inst(void)
{
        struct f_ss_opts *ss_opts;

        ss_opts = kzalloc(sizeof(*ss_opts), GFP_KERNEL);
        if (!ss_opts)
                return ERR_PTR(-ENOMEM);
        mutex_init(&ss_opts->lock);
        ss_opts->func_inst.free_func_inst = source_sink_free_instance;
        ss_opts->isoc_interval = GZERO_ISOC_INTERVAL;
        ss_opts->isoc_maxpacket = GZERO_ISOC_MAXPACKET;
        ss_opts->bulk_buflen = GZERO_BULK_BUFLEN;
        ss_opts->bulk_qlen = GZERO_SS_BULK_QLEN;
        ss_opts->iso_qlen = GZERO_SS_ISO_QLEN;

        config_group_init_type_name(&ss_opts->func_inst.group, "",
                                    &ss_func_type);

        return &ss_opts->func_inst;
}
DECLARE_USB_FUNCTION(SourceSink, source_sink_alloc_inst,
                source_sink_alloc_func);

static int __init sslb_modinit(void)
{
        int ret;

        ret = usb_function_register(&SourceSinkusb_func);
        if (ret)
                return ret;
        ret = lb_modinit();
        if (ret)
                usb_function_unregister(&SourceSinkusb_func);
        return ret;
}
static void __exit sslb_modexit(void)
{
        usb_function_unregister(&SourceSinkusb_func);
        lb_modexit();
}
module_init(sslb_modinit);
module_exit(sslb_modexit);

MODULE_LICENSE("GPL");