tcm_usb_gadget.c

Go to the documentation of this file.

/* Target based USB-Gadget
 *
 * UAS protocol handling, target callbacks, configfs handling,
 * BBB (USB Mass Storage Class Bulk-Only (BBB) and Transport protocol handling.
 *
 * Author: Sebastian Andrzej Siewior <bigeasy at linutronix dot de>
 * License: GPLv2 as published by FSF.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/configfs.h>
#include <linux/ctype.h>
#include <linux/usb/ch9.h>
#include <linux/usb/composite.h>
#include <linux/usb/gadget.h>
#include <linux/usb/storage.h>
#include <scsi/scsi.h>
#include <scsi/scsi_tcq.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/target_core_fabric_configfs.h>
#include <target/target_core_configfs.h>
#include <target/configfs_macros.h>
#include <asm/unaligned.h>

#include "tcm_usb_gadget.h"

USB_GADGET_COMPOSITE_OPTIONS();

static struct target_fabric_configfs *usbg_fabric_configfs;

static inline struct f_uas *to_f_uas(struct usb_function *f)
{
    return container_of(f, struct f_uas, function);
}

static void usbg_cmd_release(struct kref *);

static inline void usbg_cleanup_cmd(struct usbg_cmd *cmd)
{
    kref_put(&cmd->ref, usbg_cmd_release);
}

/* Start bot.c code */

static int bot_enqueue_cmd_cbw(struct f_uas *fu)
{
    int ret;

    if (fu->flags & USBG_BOT_CMD_PEND)
        return 0;

    ret = usb_ep_queue(fu->ep_out, fu->cmd.req, GFP_ATOMIC);
    if (!ret)
        fu->flags |= USBG_BOT_CMD_PEND;
    return ret;
}

static void bot_status_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct usbg_cmd *cmd = req->context;
    struct f_uas *fu = cmd->fu;

    usbg_cleanup_cmd(cmd);
    if (req->status < 0) {
        pr_err("ERR %s(%d)\n", __func__, __LINE__);
        return;
    }

    /* CSW completed, wait for next CBW */
    bot_enqueue_cmd_cbw(fu);
}

static void bot_enqueue_sense_code(struct f_uas *fu, struct usbg_cmd *cmd)
{
    struct bulk_cs_wrap *csw = &fu->bot_status.csw;
    int ret;
    u8 *sense;
    unsigned int csw_stat;

    csw_stat = cmd->csw_code;

    /*
     * We can't send SENSE as a response. So we take ASC & ASCQ from our
     * sense buffer and queue it and hope the host sends a REQUEST_SENSE
     * command where it learns why we failed.
     */
    sense = cmd->sense_iu.sense;

    csw->Tag = cmd->bot_tag;
    csw->Status = csw_stat;
    fu->bot_status.req->context = cmd;
    ret = usb_ep_queue(fu->ep_in, fu->bot_status.req, GFP_ATOMIC);
    if (ret)
        pr_err("%s(%d) ERR: %d\n", __func__, __LINE__, ret);
}

static void bot_err_compl(struct usb_ep *ep, struct usb_request *req)
{
    struct usbg_cmd *cmd = req->context;
    struct f_uas *fu = cmd->fu;

    if (req->status < 0)
        pr_err("ERR %s(%d)\n", __func__, __LINE__);

    if (cmd->data_len) {
        if (cmd->data_len > ep->maxpacket) {
            req->length = ep->maxpacket;
            cmd->data_len -= ep->maxpacket;
        } else {
            req->length = cmd->data_len;
            cmd->data_len = 0;
        }

        usb_ep_queue(ep, req, GFP_ATOMIC);
        return ;
    }
    bot_enqueue_sense_code(fu, cmd);
}

static void bot_send_bad_status(struct usbg_cmd *cmd)
{
    struct f_uas *fu = cmd->fu;
    struct bulk_cs_wrap *csw = &fu->bot_status.csw;
    struct usb_request *req;
    struct usb_ep *ep;

    csw->Residue = cpu_to_le32(cmd->data_len);

    if (cmd->data_len) {
        if (cmd->is_read) {
            ep = fu->ep_in;
            req = fu->bot_req_in;
        } else {
            ep = fu->ep_out;
            req = fu->bot_req_out;
        }

        if (cmd->data_len > fu->ep_in->maxpacket) {
            req->length = ep->maxpacket;
            cmd->data_len -= ep->maxpacket;
        } else {
            req->length = cmd->data_len;
            cmd->data_len = 0;
        }
        req->complete = bot_err_compl;
        req->context = cmd;
        req->buf = fu->cmd.buf;
        usb_ep_queue(ep, req, GFP_KERNEL);
    } else {
        bot_enqueue_sense_code(fu, cmd);
    }
}

static int bot_send_status(struct usbg_cmd *cmd, bool moved_data)
{
    struct f_uas *fu = cmd->fu;
    struct bulk_cs_wrap *csw = &fu->bot_status.csw;
    int ret;

    if (cmd->se_cmd.scsi_status == SAM_STAT_GOOD) {
        if (!moved_data && cmd->data_len) {
            /*
             * the host wants to move data, we don't. Fill / empty
             * the pipe and then send the csw with reside set.
             */
            cmd->csw_code = US_BULK_STAT_OK;
            bot_send_bad_status(cmd);
            return 0;
        }

        csw->Tag = cmd->bot_tag;
        csw->Residue = cpu_to_le32(0);
        csw->Status = US_BULK_STAT_OK;
        fu->bot_status.req->context = cmd;

        ret = usb_ep_queue(fu->ep_in, fu->bot_status.req, GFP_KERNEL);
        if (ret)
            pr_err("%s(%d) ERR: %d\n", __func__, __LINE__, ret);
    } else {
        cmd->csw_code = US_BULK_STAT_FAIL;
        bot_send_bad_status(cmd);
    }
    return 0;
}

/*
 * Called after command (no data transfer) or after the write (to device)
 * operation is completed
 */
static int bot_send_status_response(struct usbg_cmd *cmd)
{
    bool moved_data = false;

    if (!cmd->is_read)
        moved_data = true;
    return bot_send_status(cmd, moved_data);
}

/* Read request completed, now we have to send the CSW */
static void bot_read_compl(struct usb_ep *ep, struct usb_request *req)
{
    struct usbg_cmd *cmd = req->context;

    if (req->status < 0)
        pr_err("ERR %s(%d)\n", __func__, __LINE__);

    bot_send_status(cmd, true);
}

static int bot_send_read_response(struct usbg_cmd *cmd)
{
    struct f_uas *fu = cmd->fu;
    struct se_cmd *se_cmd = &cmd->se_cmd;
    struct usb_gadget *gadget = fuas_to_gadget(fu);
    int ret;

    if (!cmd->data_len) {
        cmd->csw_code = US_BULK_STAT_PHASE;
        bot_send_bad_status(cmd);
        return 0;
    }

    if (!gadget->sg_supported) {
        cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
        if (!cmd->data_buf)
            return -ENOMEM;

        sg_copy_to_buffer(se_cmd->t_data_sg,
                se_cmd->t_data_nents,
                cmd->data_buf,
                se_cmd->data_length);

        fu->bot_req_in->buf = cmd->data_buf;
    } else {
        fu->bot_req_in->buf = NULL;
        fu->bot_req_in->num_sgs = se_cmd->t_data_nents;
        fu->bot_req_in->sg = se_cmd->t_data_sg;
    }

    fu->bot_req_in->complete = bot_read_compl;
    fu->bot_req_in->length = se_cmd->data_length;
    fu->bot_req_in->context = cmd;
    ret = usb_ep_queue(fu->ep_in, fu->bot_req_in, GFP_ATOMIC);
    if (ret)
        pr_err("%s(%d)\n", __func__, __LINE__);
    return 0;
}

static void usbg_data_write_cmpl(struct usb_ep *, struct usb_request *);
static int usbg_prepare_w_request(struct usbg_cmd *, struct usb_request *);

static int bot_send_write_request(struct usbg_cmd *cmd)
{
    struct f_uas *fu = cmd->fu;
    struct se_cmd *se_cmd = &cmd->se_cmd;
    struct usb_gadget *gadget = fuas_to_gadget(fu);
    int ret;

    init_completion(&cmd->write_complete);
    cmd->fu = fu;

    if (!cmd->data_len) {
        cmd->csw_code = US_BULK_STAT_PHASE;
        return -EINVAL;
    }

    if (!gadget->sg_supported) {
        cmd->data_buf = kmalloc(se_cmd->data_length, GFP_KERNEL);
        if (!cmd->data_buf)
            return -ENOMEM;

        fu->bot_req_out->buf = cmd->data_buf;
    } else {
        fu->bot_req_out->buf = NULL;
        fu->bot_req_out->num_sgs = se_cmd->t_data_nents;
        fu->bot_req_out->sg = se_cmd->t_data_sg;
    }

    fu->bot_req_out->complete = usbg_data_write_cmpl;
    fu->bot_req_out->length = se_cmd->data_length;
    fu->bot_req_out->context = cmd;

    ret = usbg_prepare_w_request(cmd, fu->bot_req_out);
    if (ret)
        goto cleanup;
    ret = usb_ep_queue(fu->ep_out, fu->bot_req_out, GFP_KERNEL);
    if (ret)
        pr_err("%s(%d)\n", __func__, __LINE__);

    wait_for_completion(&cmd->write_complete);
    target_execute_cmd(se_cmd);
cleanup:
    return ret;
}

static int bot_submit_command(struct f_uas *, void *, unsigned int);

static void bot_cmd_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct f_uas *fu = req->context;
    int ret;

    fu->flags &= ~USBG_BOT_CMD_PEND;

    if (req->status < 0)
        return;

    ret = bot_submit_command(fu, req->buf, req->actual);
    if (ret)
        pr_err("%s(%d): %d\n", __func__, __LINE__, ret);
}

static int bot_prepare_reqs(struct f_uas *fu)
{
    int ret;

    fu->bot_req_in = usb_ep_alloc_request(fu->ep_in, GFP_KERNEL);
    if (!fu->bot_req_in)
        goto err;

    fu->bot_req_out = usb_ep_alloc_request(fu->ep_out, GFP_KERNEL);
    if (!fu->bot_req_out)
        goto err_out;

    fu->cmd.req = usb_ep_alloc_request(fu->ep_out, GFP_KERNEL);
    if (!fu->cmd.req)
        goto err_cmd;

    fu->bot_status.req = usb_ep_alloc_request(fu->ep_in, GFP_KERNEL);
    if (!fu->bot_status.req)
        goto err_sts;

    fu->bot_status.req->buf = &fu->bot_status.csw;
    fu->bot_status.req->length = US_BULK_CS_WRAP_LEN;
    fu->bot_status.req->complete = bot_status_complete;
    fu->bot_status.csw.Signature = cpu_to_le32(US_BULK_CS_SIGN);

    fu->cmd.buf = kmalloc(fu->ep_out->maxpacket, GFP_KERNEL);
    if (!fu->cmd.buf)
        goto err_buf;

    fu->cmd.req->complete = bot_cmd_complete;
    fu->cmd.req->buf = fu->cmd.buf;
    fu->cmd.req->length = fu->ep_out->maxpacket;
    fu->cmd.req->context = fu;

    ret = bot_enqueue_cmd_cbw(fu);
    if (ret)
        goto err_queue;
    return 0;
err_queue:
    kfree(fu->cmd.buf);
    fu->cmd.buf = NULL;
err_buf:
    usb_ep_free_request(fu->ep_in, fu->bot_status.req);
err_sts:
    usb_ep_free_request(fu->ep_out, fu->cmd.req);
    fu->cmd.req = NULL;
err_cmd:
    usb_ep_free_request(fu->ep_out, fu->bot_req_out);
    fu->bot_req_out = NULL;
err_out:
    usb_ep_free_request(fu->ep_in, fu->bot_req_in);
    fu->bot_req_in = NULL;
err:
    pr_err("BOT: endpoint setup failed\n");
    return -ENOMEM;
}

void bot_cleanup_old_alt(struct f_uas *fu)
{
    if (!(fu->flags & USBG_ENABLED))
        return;

    usb_ep_disable(fu->ep_in);
    usb_ep_disable(fu->ep_out);

    if (!fu->bot_req_in)
        return;

    usb_ep_free_request(fu->ep_in, fu->bot_req_in);
    usb_ep_free_request(fu->ep_out, fu->bot_req_out);
    usb_ep_free_request(fu->ep_out, fu->cmd.req);
    usb_ep_free_request(fu->ep_out, fu->bot_status.req);

    kfree(fu->cmd.buf);

    fu->bot_req_in = NULL;
    fu->bot_req_out = NULL;
    fu->cmd.req = NULL;
    fu->bot_status.req = NULL;
    fu->cmd.buf = NULL;
}

static void bot_set_alt(struct f_uas *fu)
{
    struct usb_function *f = &fu->function;
    struct usb_gadget *gadget = f->config->cdev->gadget;
    int ret;

    fu->flags = USBG_IS_BOT;

    config_ep_by_speed(gadget, f, fu->ep_in);
    ret = usb_ep_enable(fu->ep_in);
    if (ret)
        goto err_b_in;

    config_ep_by_speed(gadget, f, fu->ep_out);
    ret = usb_ep_enable(fu->ep_out);
    if (ret)
        goto err_b_out;

    ret = bot_prepare_reqs(fu);
    if (ret)
        goto err_wq;
    fu->flags |= USBG_ENABLED;
    pr_info("Using the BOT protocol\n");
    return;
err_wq:
    usb_ep_disable(fu->ep_out);
err_b_out:
    usb_ep_disable(fu->ep_in);
err_b_in:
    fu->flags = USBG_IS_BOT;
}

static int usbg_bot_setup(struct usb_function *f,
        const struct usb_ctrlrequest *ctrl)
{
    struct f_uas *fu = to_f_uas(f);
    struct usb_composite_dev *cdev = f->config->cdev;
    u16 w_value = le16_to_cpu(ctrl->wValue);
    u16 w_length = le16_to_cpu(ctrl->wLength);
    int luns;
    u8 *ret_lun;

    switch (ctrl->bRequest) {
    case US_BULK_GET_MAX_LUN:
        if (ctrl->bRequestType != (USB_DIR_IN | USB_TYPE_CLASS |
                    USB_RECIP_INTERFACE))
            return -ENOTSUPP;

        if (w_length < 1)
            return -EINVAL;
        if (w_value != 0)
            return -EINVAL;
        luns = atomic_read(&fu->tpg->tpg_port_count);
        if (!luns) {
            pr_err("No LUNs configured?\n");
            return -EINVAL;
        }
        /*
         * If 4 LUNs are present we return 3 i.e. LUN 0..3 can be
         * accessed. The upper limit is 0xf
         */
        luns--;
        if (luns > 0xf) {
            pr_info_once("Limiting the number of luns to 16\n");
            luns = 0xf;
        }
        ret_lun = cdev->req->buf;
        *ret_lun = luns;
        cdev->req->length = 1;
        return usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
        break;

    case US_BULK_RESET_REQUEST:
        /* XXX maybe we should remove previous requests for IN + OUT */
        bot_enqueue_cmd_cbw(fu);
        return 0;
        break;
    };
    return -ENOTSUPP;
}

/* Start uas.c code */

static void uasp_cleanup_one_stream(struct f_uas *fu, struct uas_stream *stream)
{
    /* We have either all three allocated or none */
    if (!stream->req_in)
        return;

    usb_ep_free_request(fu->ep_in, stream->req_in);
    usb_ep_free_request(fu->ep_out, stream->req_out);
    usb_ep_free_request(fu->ep_status, stream->req_status);

    stream->req_in = NULL;
    stream->req_out = NULL;
    stream->req_status = NULL;
}

static void uasp_free_cmdreq(struct f_uas *fu)
{
    usb_ep_free_request(fu->ep_cmd, fu->cmd.req);
    kfree(fu->cmd.buf);
    fu->cmd.req = NULL;
    fu->cmd.buf = NULL;
}

static void uasp_cleanup_old_alt(struct f_uas *fu)
{
    int i;

    if (!(fu->flags & USBG_ENABLED))
        return;

    usb_ep_disable(fu->ep_in);
    usb_ep_disable(fu->ep_out);
    usb_ep_disable(fu->ep_status);
    usb_ep_disable(fu->ep_cmd);

    for (i = 0; i < UASP_SS_EP_COMP_NUM_STREAMS; i++)
        uasp_cleanup_one_stream(fu, &fu->stream[i]);
    uasp_free_cmdreq(fu);
}

static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req);

static int uasp_prepare_r_request(struct usbg_cmd *cmd)
{
    struct se_cmd *se_cmd = &cmd->se_cmd;
    struct f_uas *fu = cmd->fu;
    struct usb_gadget *gadget = fuas_to_gadget(fu);
    struct uas_stream *stream = cmd->stream;

    if (!gadget->sg_supported) {
        cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
        if (!cmd->data_buf)
            return -ENOMEM;

        sg_copy_to_buffer(se_cmd->t_data_sg,
                se_cmd->t_data_nents,
                cmd->data_buf,
                se_cmd->data_length);

        stream->req_in->buf = cmd->data_buf;
    } else {
        stream->req_in->buf = NULL;
        stream->req_in->num_sgs = se_cmd->t_data_nents;
        stream->req_in->sg = se_cmd->t_data_sg;
    }

    stream->req_in->complete = uasp_status_data_cmpl;
    stream->req_in->length = se_cmd->data_length;
    stream->req_in->context = cmd;

    cmd->state = UASP_SEND_STATUS;
    return 0;
}

static void uasp_prepare_status(struct usbg_cmd *cmd)
{
    struct se_cmd *se_cmd = &cmd->se_cmd;
    struct sense_iu *iu = &cmd->sense_iu;
    struct uas_stream *stream = cmd->stream;

    cmd->state = UASP_QUEUE_COMMAND;
    iu->iu_id = IU_ID_STATUS;
    iu->tag = cpu_to_be16(cmd->tag);

    /*
     * iu->status_qual = cpu_to_be16(STATUS QUALIFIER SAM-4. Where R U?);
     */
    iu->len = cpu_to_be16(se_cmd->scsi_sense_length);
    iu->status = se_cmd->scsi_status;
    stream->req_status->context = cmd;
    stream->req_status->length = se_cmd->scsi_sense_length + 16;
    stream->req_status->buf = iu;
    stream->req_status->complete = uasp_status_data_cmpl;
}

static void uasp_status_data_cmpl(struct usb_ep *ep, struct usb_request *req)
{
    struct usbg_cmd *cmd = req->context;
    struct uas_stream *stream = cmd->stream;
    struct f_uas *fu = cmd->fu;
    int ret;

    if (req->status < 0)
        goto cleanup;

    switch (cmd->state) {
    case UASP_SEND_DATA:
        ret = uasp_prepare_r_request(cmd);
        if (ret)
            goto cleanup;
        ret = usb_ep_queue(fu->ep_in, stream->req_in, GFP_ATOMIC);
        if (ret)
            pr_err("%s(%d) => %d\n", __func__, __LINE__, ret);
        break;

    case UASP_RECEIVE_DATA:
        ret = usbg_prepare_w_request(cmd, stream->req_out);
        if (ret)
            goto cleanup;
        ret = usb_ep_queue(fu->ep_out, stream->req_out, GFP_ATOMIC);
        if (ret)
            pr_err("%s(%d) => %d\n", __func__, __LINE__, ret);
        break;

    case UASP_SEND_STATUS:
        uasp_prepare_status(cmd);
        ret = usb_ep_queue(fu->ep_status, stream->req_status,
                GFP_ATOMIC);
        if (ret)
            pr_err("%s(%d) => %d\n", __func__, __LINE__, ret);
        break;

    case UASP_QUEUE_COMMAND:
        usbg_cleanup_cmd(cmd);
        usb_ep_queue(fu->ep_cmd, fu->cmd.req, GFP_ATOMIC);
        break;

    default:
        BUG();
    };
    return;

cleanup:
    usbg_cleanup_cmd(cmd);
}

static int uasp_send_status_response(struct usbg_cmd *cmd)
{
    struct f_uas *fu = cmd->fu;
    struct uas_stream *stream = cmd->stream;
    struct sense_iu *iu = &cmd->sense_iu;

    iu->tag = cpu_to_be16(cmd->tag);
    stream->req_status->complete = uasp_status_data_cmpl;
    stream->req_status->context = cmd;
    cmd->fu = fu;
    uasp_prepare_status(cmd);
    return usb_ep_queue(fu->ep_status, stream->req_status, GFP_ATOMIC);
}

static int uasp_send_read_response(struct usbg_cmd *cmd)
{
    struct f_uas *fu = cmd->fu;
    struct uas_stream *stream = cmd->stream;
    struct sense_iu *iu = &cmd->sense_iu;
    int ret;

    cmd->fu = fu;

    iu->tag = cpu_to_be16(cmd->tag);
    if (fu->flags & USBG_USE_STREAMS) {

        ret = uasp_prepare_r_request(cmd);
        if (ret)
            goto out;
        ret = usb_ep_queue(fu->ep_in, stream->req_in, GFP_ATOMIC);
        if (ret) {
            pr_err("%s(%d) => %d\n", __func__, __LINE__, ret);
            kfree(cmd->data_buf);
            cmd->data_buf = NULL;
        }

    } else {

        iu->iu_id = IU_ID_READ_READY;
        iu->tag = cpu_to_be16(cmd->tag);

        stream->req_status->complete = uasp_status_data_cmpl;
        stream->req_status->context = cmd;

        cmd->state = UASP_SEND_DATA;
        stream->req_status->buf = iu;
        stream->req_status->length = sizeof(struct iu);

        ret = usb_ep_queue(fu->ep_status, stream->req_status,
                GFP_ATOMIC);
        if (ret)
            pr_err("%s(%d) => %d\n", __func__, __LINE__, ret);
    }
out:
    return ret;
}

static int uasp_send_write_request(struct usbg_cmd *cmd)
{
    struct f_uas *fu = cmd->fu;
    struct se_cmd *se_cmd = &cmd->se_cmd;
    struct uas_stream *stream = cmd->stream;
    struct sense_iu *iu = &cmd->sense_iu;
    int ret;

    init_completion(&cmd->write_complete);
    cmd->fu = fu;

    iu->tag = cpu_to_be16(cmd->tag);

    if (fu->flags & USBG_USE_STREAMS) {

        ret = usbg_prepare_w_request(cmd, stream->req_out);
        if (ret)
            goto cleanup;
        ret = usb_ep_queue(fu->ep_out, stream->req_out, GFP_ATOMIC);
        if (ret)
            pr_err("%s(%d)\n", __func__, __LINE__);

    } else {

        iu->iu_id = IU_ID_WRITE_READY;
        iu->tag = cpu_to_be16(cmd->tag);

        stream->req_status->complete = uasp_status_data_cmpl;
        stream->req_status->context = cmd;

        cmd->state = UASP_RECEIVE_DATA;
        stream->req_status->buf = iu;
        stream->req_status->length = sizeof(struct iu);

        ret = usb_ep_queue(fu->ep_status, stream->req_status,
                GFP_ATOMIC);
        if (ret)
            pr_err("%s(%d)\n", __func__, __LINE__);
    }

    wait_for_completion(&cmd->write_complete);
    target_execute_cmd(se_cmd);
cleanup:
    return ret;
}

static int usbg_submit_command(struct f_uas *, void *, unsigned int);

static void uasp_cmd_complete(struct usb_ep *ep, struct usb_request *req)
{
    struct f_uas *fu = req->context;
    int ret;

    if (req->status < 0)
        return;

    ret = usbg_submit_command(fu, req->buf, req->actual);
    /*
     * Once we tune for performance enqueue the command req here again so
     * we can receive a second command while we processing this one. Pay
     * attention to properly sync STAUS endpoint with DATA IN + OUT so you
     * don't break HS.
     */
    if (!ret)
        return;
    usb_ep_queue(fu->ep_cmd, fu->cmd.req, GFP_ATOMIC);
}

static int uasp_alloc_stream_res(struct f_uas *fu, struct uas_stream *stream)
{
    stream->req_in = usb_ep_alloc_request(fu->ep_in, GFP_KERNEL);
    if (!stream->req_in)
        goto out;

    stream->req_out = usb_ep_alloc_request(fu->ep_out, GFP_KERNEL);
    if (!stream->req_out)
        goto err_out;

    stream->req_status = usb_ep_alloc_request(fu->ep_status, GFP_KERNEL);
    if (!stream->req_status)
        goto err_sts;

    return 0;
err_sts:
    usb_ep_free_request(fu->ep_status, stream->req_status);
    stream->req_status = NULL;
err_out:
    usb_ep_free_request(fu->ep_out, stream->req_out);
    stream->req_out = NULL;
out:
    return -ENOMEM;
}

static int uasp_alloc_cmd(struct f_uas *fu)
{
    fu->cmd.req = usb_ep_alloc_request(fu->ep_cmd, GFP_KERNEL);
    if (!fu->cmd.req)
        goto err;

    fu->cmd.buf = kmalloc(fu->ep_cmd->maxpacket, GFP_KERNEL);
    if (!fu->cmd.buf)
        goto err_buf;

    fu->cmd.req->complete = uasp_cmd_complete;
    fu->cmd.req->buf = fu->cmd.buf;
    fu->cmd.req->length = fu->ep_cmd->maxpacket;
    fu->cmd.req->context = fu;
    return 0;

err_buf:
    usb_ep_free_request(fu->ep_cmd, fu->cmd.req);
err:
    return -ENOMEM;
}

static void uasp_setup_stream_res(struct f_uas *fu, int max_streams)
{
    int i;

    for (i = 0; i < max_streams; i++) {
        struct uas_stream *s = &fu->stream[i];

        s->req_in->stream_id = i + 1;
        s->req_out->stream_id = i + 1;
        s->req_status->stream_id = i + 1;
    }
}

static int uasp_prepare_reqs(struct f_uas *fu)
{
    int ret;
    int i;
    int max_streams;

    if (fu->flags & USBG_USE_STREAMS)
        max_streams = UASP_SS_EP_COMP_NUM_STREAMS;
    else
        max_streams = 1;

    for (i = 0; i < max_streams; i++) {
        ret = uasp_alloc_stream_res(fu, &fu->stream[i]);
        if (ret)
            goto err_cleanup;
    }

    ret = uasp_alloc_cmd(fu);
    if (ret)
        goto err_free_stream;
    uasp_setup_stream_res(fu, max_streams);

    ret = usb_ep_queue(fu->ep_cmd, fu->cmd.req, GFP_ATOMIC);
    if (ret)
        goto err_free_stream;

    return 0;

err_free_stream:
    uasp_free_cmdreq(fu);

err_cleanup:
    if (i) {
        do {
            uasp_cleanup_one_stream(fu, &fu->stream[i - 1]);
            i--;
        } while (i);
    }
    pr_err("UASP: endpoint setup failed\n");
    return ret;
}

static void uasp_set_alt(struct f_uas *fu)
{
    struct usb_function *f = &fu->function;
    struct usb_gadget *gadget = f->config->cdev->gadget;
    int ret;

    fu->flags = USBG_IS_UAS;

    if (gadget->speed == USB_SPEED_SUPER)
        fu->flags |= USBG_USE_STREAMS;

    config_ep_by_speed(gadget, f, fu->ep_in);
    ret = usb_ep_enable(fu->ep_in);
    if (ret)
        goto err_b_in;

    config_ep_by_speed(gadget, f, fu->ep_out);
    ret = usb_ep_enable(fu->ep_out);
    if (ret)
        goto err_b_out;

    config_ep_by_speed(gadget, f, fu->ep_cmd);
    ret = usb_ep_enable(fu->ep_cmd);
    if (ret)
        goto err_cmd;
    config_ep_by_speed(gadget, f, fu->ep_status);
    ret = usb_ep_enable(fu->ep_status);
    if (ret)
        goto err_status;

    ret = uasp_prepare_reqs(fu);
    if (ret)
        goto err_wq;
    fu->flags |= USBG_ENABLED;

    pr_info("Using the UAS protocol\n");
    return;
err_wq:
    usb_ep_disable(fu->ep_status);
err_status:
    usb_ep_disable(fu->ep_cmd);
err_cmd:
    usb_ep_disable(fu->ep_out);
err_b_out:
    usb_ep_disable(fu->ep_in);
err_b_in:
    fu->flags = 0;
}

static int get_cmd_dir(const unsigned char *cdb)
{
    int ret;

    switch (cdb[0]) {
    case READ_6:
    case READ_10:
    case READ_12:
    case READ_16:
    case INQUIRY:
    case MODE_SENSE:
    case MODE_SENSE_10:
    case SERVICE_ACTION_IN:
    case MAINTENANCE_IN:
    case PERSISTENT_RESERVE_IN:
    case SECURITY_PROTOCOL_IN:
    case ACCESS_CONTROL_IN:
    case REPORT_LUNS:
    case READ_BLOCK_LIMITS:
    case READ_POSITION:
    case READ_CAPACITY:
    case READ_TOC:
    case READ_FORMAT_CAPACITIES:
    case REQUEST_SENSE:
        ret = DMA_FROM_DEVICE;
        break;

    case WRITE_6:
    case WRITE_10:
    case WRITE_12:
    case WRITE_16:
    case MODE_SELECT:
    case MODE_SELECT_10:
    case WRITE_VERIFY:
    case WRITE_VERIFY_12:
    case PERSISTENT_RESERVE_OUT:
    case MAINTENANCE_OUT:
    case SECURITY_PROTOCOL_OUT:
    case ACCESS_CONTROL_OUT:
        ret = DMA_TO_DEVICE;
        break;
    case ALLOW_MEDIUM_REMOVAL:
    case TEST_UNIT_READY:
    case SYNCHRONIZE_CACHE:
    case START_STOP:
    case ERASE:
    case REZERO_UNIT:
    case SEEK_10:
    case SPACE:
    case VERIFY:
    case WRITE_FILEMARKS:
        ret = DMA_NONE;
        break;
    default:
        pr_warn("target: Unknown data direction for SCSI Opcode "
                "0x%02x\n", cdb[0]);
        ret = -EINVAL;
    }
    return ret;
}

static void usbg_data_write_cmpl(struct usb_ep *ep, struct usb_request *req)
{
    struct usbg_cmd *cmd = req->context;
    struct se_cmd *se_cmd = &cmd->se_cmd;

    if (req->status < 0) {
        pr_err("%s() state %d transfer failed\n", __func__, cmd->state);
        goto cleanup;
    }

    if (req->num_sgs == 0) {
        sg_copy_from_buffer(se_cmd->t_data_sg,
                se_cmd->t_data_nents,
                cmd->data_buf,
                se_cmd->data_length);
    }

    complete(&cmd->write_complete);
    return;

cleanup:
    usbg_cleanup_cmd(cmd);
}

static int usbg_prepare_w_request(struct usbg_cmd *cmd, struct usb_request *req)
{
    struct se_cmd *se_cmd = &cmd->se_cmd;
    struct f_uas *fu = cmd->fu;
    struct usb_gadget *gadget = fuas_to_gadget(fu);

    if (!gadget->sg_supported) {
        cmd->data_buf = kmalloc(se_cmd->data_length, GFP_ATOMIC);
        if (!cmd->data_buf)
            return -ENOMEM;

        req->buf = cmd->data_buf;
    } else {
        req->buf = NULL;
        req->num_sgs = se_cmd->t_data_nents;
        req->sg = se_cmd->t_data_sg;
    }

    req->complete = usbg_data_write_cmpl;
    req->length = se_cmd->data_length;
    req->context = cmd;
    return 0;
}

static int usbg_send_status_response(struct se_cmd *se_cmd)
{
    struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
            se_cmd);
    struct f_uas *fu = cmd->fu;

    if (fu->flags & USBG_IS_BOT)
        return bot_send_status_response(cmd);
    else
        return uasp_send_status_response(cmd);
}

static int usbg_send_write_request(struct se_cmd *se_cmd)
{
    struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
            se_cmd);
    struct f_uas *fu = cmd->fu;

    if (fu->flags & USBG_IS_BOT)
        return bot_send_write_request(cmd);
    else
        return uasp_send_write_request(cmd);
}

static int usbg_send_read_response(struct se_cmd *se_cmd)
{
    struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
            se_cmd);
    struct f_uas *fu = cmd->fu;

    if (fu->flags & USBG_IS_BOT)
        return bot_send_read_response(cmd);
    else
        return uasp_send_read_response(cmd);
}

static void usbg_cmd_work(struct work_struct *work)
{
    struct usbg_cmd *cmd = container_of(work, struct usbg_cmd, work);
    struct se_cmd *se_cmd;
    struct tcm_usbg_nexus *tv_nexus;
    struct usbg_tpg *tpg;
    int dir;

    se_cmd = &cmd->se_cmd;
    tpg = cmd->fu->tpg;
    tv_nexus = tpg->tpg_nexus;
    dir = get_cmd_dir(cmd->cmd_buf);
    if (dir < 0) {
        transport_init_se_cmd(se_cmd,
                tv_nexus->tvn_se_sess->se_tpg->se_tpg_tfo,
                tv_nexus->tvn_se_sess, cmd->data_len, DMA_NONE,
                cmd->prio_attr, cmd->sense_iu.sense);
        goto out;
    }

    if (target_submit_cmd(se_cmd, tv_nexus->tvn_se_sess,
            cmd->cmd_buf, cmd->sense_iu.sense, cmd->unpacked_lun,
            0, cmd->prio_attr, dir, TARGET_SCF_UNKNOWN_SIZE) < 0)
        goto out;

    return;

out:
    transport_send_check_condition_and_sense(se_cmd,
            TCM_UNSUPPORTED_SCSI_OPCODE, 1);
    usbg_cleanup_cmd(cmd);
}

static int usbg_submit_command(struct f_uas *fu,
        void *cmdbuf, unsigned int len)
{
    struct command_iu *cmd_iu = cmdbuf;
    struct usbg_cmd *cmd;
    struct usbg_tpg *tpg;
    struct se_cmd *se_cmd;
    struct tcm_usbg_nexus *tv_nexus;
    u32 cmd_len;
    int ret;

    if (cmd_iu->iu_id != IU_ID_COMMAND) {
        pr_err("Unsupported type %d\n", cmd_iu->iu_id);
        return -EINVAL;
    }

    cmd = kzalloc(sizeof *cmd, GFP_ATOMIC);
    if (!cmd)
        return -ENOMEM;

    cmd->fu = fu;

    /* XXX until I figure out why I can't free in on complete */
    kref_init(&cmd->ref);
    kref_get(&cmd->ref);

    tpg = fu->tpg;
    cmd_len = (cmd_iu->len & ~0x3) + 16;
    if (cmd_len > USBG_MAX_CMD)
        goto err;

    memcpy(cmd->cmd_buf, cmd_iu->cdb, cmd_len);

    cmd->tag = be16_to_cpup(&cmd_iu->tag);
    if (fu->flags & USBG_USE_STREAMS) {
        if (cmd->tag > UASP_SS_EP_COMP_NUM_STREAMS)
            goto err;
        if (!cmd->tag)
            cmd->stream = &fu->stream[0];
        else
            cmd->stream = &fu->stream[cmd->tag - 1];
    } else {
        cmd->stream = &fu->stream[0];
    }

    tv_nexus = tpg->tpg_nexus;
    if (!tv_nexus) {
        pr_err("Missing nexus, ignoring command\n");
        goto err;
    }

    switch (cmd_iu->prio_attr & 0x7) {
    case UAS_HEAD_TAG:
        cmd->prio_attr = MSG_HEAD_TAG;
        break;
    case UAS_ORDERED_TAG:
        cmd->prio_attr = MSG_ORDERED_TAG;
        break;
    case UAS_ACA:
        cmd->prio_attr = MSG_ACA_TAG;
        break;
    default:
        pr_debug_once("Unsupported prio_attr: %02x.\n",
                cmd_iu->prio_attr);
    case UAS_SIMPLE_TAG:
        cmd->prio_attr = MSG_SIMPLE_TAG;
        break;
    }

    se_cmd = &cmd->se_cmd;
    cmd->unpacked_lun = scsilun_to_int(&cmd_iu->lun);

    INIT_WORK(&cmd->work, usbg_cmd_work);
    ret = queue_work(tpg->workqueue, &cmd->work);
    if (ret < 0)
        goto err;

    return 0;
err:
    kfree(cmd);
    return -EINVAL;
}

static void bot_cmd_work(struct work_struct *work)
{
    struct usbg_cmd *cmd = container_of(work, struct usbg_cmd, work);
    struct se_cmd *se_cmd;
    struct tcm_usbg_nexus *tv_nexus;
    struct usbg_tpg *tpg;
    int dir;

    se_cmd = &cmd->se_cmd;
    tpg = cmd->fu->tpg;
    tv_nexus = tpg->tpg_nexus;
    dir = get_cmd_dir(cmd->cmd_buf);
    if (dir < 0) {
        transport_init_se_cmd(se_cmd,
                tv_nexus->tvn_se_sess->se_tpg->se_tpg_tfo,
                tv_nexus->tvn_se_sess, cmd->data_len, DMA_NONE,
                cmd->prio_attr, cmd->sense_iu.sense);
        goto out;
    }

    if (target_submit_cmd(se_cmd, tv_nexus->tvn_se_sess,
            cmd->cmd_buf, cmd->sense_iu.sense, cmd->unpacked_lun,
            cmd->data_len, cmd->prio_attr, dir, 0) < 0)
        goto out;

    return;

out:
    transport_send_check_condition_and_sense(se_cmd,
                TCM_UNSUPPORTED_SCSI_OPCODE, 1);
    usbg_cleanup_cmd(cmd);
}

static int bot_submit_command(struct f_uas *fu,
        void *cmdbuf, unsigned int len)
{
    struct bulk_cb_wrap *cbw = cmdbuf;
    struct usbg_cmd *cmd;
    struct usbg_tpg *tpg;
    struct se_cmd *se_cmd;
    struct tcm_usbg_nexus *tv_nexus;
    u32 cmd_len;
    int ret;

    if (cbw->Signature != cpu_to_le32(US_BULK_CB_SIGN)) {
        pr_err("Wrong signature on CBW\n");
        return -EINVAL;
    }
    if (len != 31) {
        pr_err("Wrong length for CBW\n");
        return -EINVAL;
    }

    cmd_len = cbw->Length;
    if (cmd_len < 1 || cmd_len > 16)
        return -EINVAL;

    cmd = kzalloc(sizeof *cmd, GFP_ATOMIC);
    if (!cmd)
        return -ENOMEM;

    cmd->fu = fu;

    /* XXX until I figure out why I can't free in on complete */
    kref_init(&cmd->ref);
    kref_get(&cmd->ref);

    tpg = fu->tpg;

    memcpy(cmd->cmd_buf, cbw->CDB, cmd_len);

    cmd->bot_tag = cbw->Tag;

    tv_nexus = tpg->tpg_nexus;
    if (!tv_nexus) {
        pr_err("Missing nexus, ignoring command\n");
        goto err;
    }

    cmd->prio_attr = MSG_SIMPLE_TAG;
    se_cmd = &cmd->se_cmd;
    cmd->unpacked_lun = cbw->Lun;
    cmd->is_read = cbw->Flags & US_BULK_FLAG_IN ? 1 : 0;
    cmd->data_len = le32_to_cpu(cbw->DataTransferLength);

    INIT_WORK(&cmd->work, bot_cmd_work);
    ret = queue_work(tpg->workqueue, &cmd->work);
    if (ret < 0)
        goto err;

    return 0;
err:
    kfree(cmd);
    return -EINVAL;
}

/* Start fabric.c code */

static int usbg_check_true(struct se_portal_group *se_tpg)
{
    return 1;
}

static int usbg_check_false(struct se_portal_group *se_tpg)
{
    return 0;
}

static char *usbg_get_fabric_name(void)
{
    return "usb_gadget";
}

static u8 usbg_get_fabric_proto_ident(struct se_portal_group *se_tpg)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);
    struct usbg_tport *tport = tpg->tport;
    u8 proto_id;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
    default:
        proto_id = sas_get_fabric_proto_ident(se_tpg);
        break;
    }

    return proto_id;
}

static char *usbg_get_fabric_wwn(struct se_portal_group *se_tpg)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);
    struct usbg_tport *tport = tpg->tport;

    return &tport->tport_name[0];
}

static u16 usbg_get_tag(struct se_portal_group *se_tpg)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);
    return tpg->tport_tpgt;
}

static u32 usbg_get_default_depth(struct se_portal_group *se_tpg)
{
    return 1;
}

static u32 usbg_get_pr_transport_id(
    struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl,
    struct t10_pr_registration *pr_reg,
    int *format_code,
    unsigned char *buf)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);
    struct usbg_tport *tport = tpg->tport;
    int ret = 0;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
    default:
        ret = sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
        break;
    }

    return ret;
}

static u32 usbg_get_pr_transport_id_len(
    struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl,
    struct t10_pr_registration *pr_reg,
    int *format_code)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);
    struct usbg_tport *tport = tpg->tport;
    int ret = 0;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
    default:
        ret = sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
        break;
    }

    return ret;
}

static char *usbg_parse_pr_out_transport_id(
    struct se_portal_group *se_tpg,
    const char *buf,
    u32 *out_tid_len,
    char **port_nexus_ptr)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);
    struct usbg_tport *tport = tpg->tport;
    char *tid = NULL;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
    default:
        tid = sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    }

    return tid;
}

static struct se_node_acl *usbg_alloc_fabric_acl(struct se_portal_group *se_tpg)
{
    struct usbg_nacl *nacl;

    nacl = kzalloc(sizeof(struct usbg_nacl), GFP_KERNEL);
    if (!nacl) {
        printk(KERN_ERR "Unable to alocate struct usbg_nacl\n");
        return NULL;
    }

    return &nacl->se_node_acl;
}

static void usbg_release_fabric_acl(
    struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl)
{
    struct usbg_nacl *nacl = container_of(se_nacl,
            struct usbg_nacl, se_node_acl);
    kfree(nacl);
}

static u32 usbg_tpg_get_inst_index(struct se_portal_group *se_tpg)
{
    return 1;
}

static void usbg_cmd_release(struct kref *ref)
{
    struct usbg_cmd *cmd = container_of(ref, struct usbg_cmd,
            ref);

    transport_generic_free_cmd(&cmd->se_cmd, 0);
}

static void usbg_release_cmd(struct se_cmd *se_cmd)
{
    struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
            se_cmd);
    kfree(cmd->data_buf);
    kfree(cmd);
    return;
}

static int usbg_shutdown_session(struct se_session *se_sess)
{
    return 0;
}

static void usbg_close_session(struct se_session *se_sess)
{
    return;
}

static u32 usbg_sess_get_index(struct se_session *se_sess)
{
    return 0;
}

/*
 * XXX Error recovery: return != 0 if we expect writes. Dunno when that could be
 */
static int usbg_write_pending_status(struct se_cmd *se_cmd)
{
    return 0;
}

static void usbg_set_default_node_attrs(struct se_node_acl *nacl)
{
    return;
}

static u32 usbg_get_task_tag(struct se_cmd *se_cmd)
{
    struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
            se_cmd);
    struct f_uas *fu = cmd->fu;

    if (fu->flags & USBG_IS_BOT)
        return le32_to_cpu(cmd->bot_tag);
    else
        return cmd->tag;
}

static int usbg_get_cmd_state(struct se_cmd *se_cmd)
{
    return 0;
}

static int usbg_queue_tm_rsp(struct se_cmd *se_cmd)
{
    return 0;
}

static const char *usbg_check_wwn(const char *name)
{
    const char *n;
    unsigned int len;

    n = strstr(name, "naa.");
    if (!n)
        return NULL;
    n += 4;
    len = strlen(n);
    if (len == 0 || len > USBG_NAMELEN - 1)
        return NULL;
    return n;
}

static struct se_node_acl *usbg_make_nodeacl(
    struct se_portal_group *se_tpg,
    struct config_group *group,
    const char *name)
{
    struct se_node_acl *se_nacl, *se_nacl_new;
    struct usbg_nacl *nacl;
    u64 wwpn = 0;
    u32 nexus_depth;
    const char *wnn_name;

    wnn_name = usbg_check_wwn(name);
    if (!wnn_name)
        return ERR_PTR(-EINVAL);
    se_nacl_new = usbg_alloc_fabric_acl(se_tpg);
    if (!(se_nacl_new))
        return ERR_PTR(-ENOMEM);

    nexus_depth = 1;
    /*
     * se_nacl_new may be released by core_tpg_add_initiator_node_acl()
     * when converting a NodeACL from demo mode -> explict
     */
    se_nacl = core_tpg_add_initiator_node_acl(se_tpg, se_nacl_new,
                name, nexus_depth);
    if (IS_ERR(se_nacl)) {
        usbg_release_fabric_acl(se_tpg, se_nacl_new);
        return se_nacl;
    }
    /*
     * Locate our struct usbg_nacl and set the FC Nport WWPN
     */
    nacl = container_of(se_nacl, struct usbg_nacl, se_node_acl);
    nacl->iport_wwpn = wwpn;
    snprintf(nacl->iport_name, sizeof(nacl->iport_name), "%s", name);
    return se_nacl;
}

static void usbg_drop_nodeacl(struct se_node_acl *se_acl)
{
    struct usbg_nacl *nacl = container_of(se_acl,
                struct usbg_nacl, se_node_acl);
    core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
    kfree(nacl);
}

struct usbg_tpg *the_only_tpg_I_currently_have;

static struct se_portal_group *usbg_make_tpg(
    struct se_wwn *wwn,
    struct config_group *group,
    const char *name)
{
    struct usbg_tport *tport = container_of(wwn, struct usbg_tport,
            tport_wwn);
    struct usbg_tpg *tpg;
    unsigned long tpgt;
    int ret;

    if (strstr(name, "tpgt_") != name)
        return ERR_PTR(-EINVAL);
    if (kstrtoul(name + 5, 0, &tpgt) || tpgt > UINT_MAX)
        return ERR_PTR(-EINVAL);
    if (the_only_tpg_I_currently_have) {
        pr_err("Until the gadget framework can't handle multiple\n");
        pr_err("gadgets, you can't do this here.\n");
        return ERR_PTR(-EBUSY);
    }

    tpg = kzalloc(sizeof(struct usbg_tpg), GFP_KERNEL);
    if (!tpg) {
        printk(KERN_ERR "Unable to allocate struct usbg_tpg");
        return ERR_PTR(-ENOMEM);
    }
    mutex_init(&tpg->tpg_mutex);
    atomic_set(&tpg->tpg_port_count, 0);
    tpg->workqueue = alloc_workqueue("tcm_usb_gadget", 0, 1);
    if (!tpg->workqueue) {
        kfree(tpg);
        return NULL;
    }

    tpg->tport = tport;
    tpg->tport_tpgt = tpgt;

    ret = core_tpg_register(&usbg_fabric_configfs->tf_ops, wwn,
                &tpg->se_tpg, tpg,
                TRANSPORT_TPG_TYPE_NORMAL);
    if (ret < 0) {
        destroy_workqueue(tpg->workqueue);
        kfree(tpg);
        return NULL;
    }
    the_only_tpg_I_currently_have = tpg;
    return &tpg->se_tpg;
}

static void usbg_drop_tpg(struct se_portal_group *se_tpg)
{
    struct usbg_tpg *tpg = container_of(se_tpg,
                struct usbg_tpg, se_tpg);

    core_tpg_deregister(se_tpg);
    destroy_workqueue(tpg->workqueue);
    kfree(tpg);
    the_only_tpg_I_currently_have = NULL;
}

static struct se_wwn *usbg_make_tport(
    struct target_fabric_configfs *tf,
    struct config_group *group,
    const char *name)
{
    struct usbg_tport *tport;
    const char *wnn_name;
    u64 wwpn = 0;

    wnn_name = usbg_check_wwn(name);
    if (!wnn_name)
        return ERR_PTR(-EINVAL);

    tport = kzalloc(sizeof(struct usbg_tport), GFP_KERNEL);
    if (!(tport)) {
        printk(KERN_ERR "Unable to allocate struct usbg_tport");
        return ERR_PTR(-ENOMEM);
    }
    tport->tport_wwpn = wwpn;
    snprintf(tport->tport_name, sizeof(tport->tport_name), wnn_name);
    return &tport->tport_wwn;
}

static void usbg_drop_tport(struct se_wwn *wwn)
{
    struct usbg_tport *tport = container_of(wwn,
                struct usbg_tport, tport_wwn);
    kfree(tport);
}

/*
 * If somebody feels like dropping the version property, go ahead.
 */
static ssize_t usbg_wwn_show_attr_version(
    struct target_fabric_configfs *tf,
    char *page)
{
    return sprintf(page, "usb-gadget fabric module\n");
}
TF_WWN_ATTR_RO(usbg, version);

static struct configfs_attribute *usbg_wwn_attrs[] = {
    &usbg_wwn_version.attr,
    NULL,
};

static ssize_t tcm_usbg_tpg_show_enable(
        struct se_portal_group *se_tpg,
        char *page)
{
    struct usbg_tpg  *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);

    return snprintf(page, PAGE_SIZE, "%u\n", tpg->gadget_connect);
}

static int usbg_attach(struct usbg_tpg *);
static void usbg_detach(struct usbg_tpg *);

static ssize_t tcm_usbg_tpg_store_enable(
        struct se_portal_group *se_tpg,
        const char *page,
        size_t count)
{
    struct usbg_tpg  *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);
    unsigned long op;
    ssize_t ret;

    ret = kstrtoul(page, 0, &op);
    if (ret < 0)
        return -EINVAL;
    if (op > 1)
        return -EINVAL;

    if (op && tpg->gadget_connect)
        goto out;
    if (!op && !tpg->gadget_connect)
        goto out;

    if (op) {
        ret = usbg_attach(tpg);
        if (ret)
            goto out;
    } else {
        usbg_detach(tpg);
    }
    tpg->gadget_connect = op;
out:
    return count;
}
TF_TPG_BASE_ATTR(tcm_usbg, enable, S_IRUGO | S_IWUSR);

static ssize_t tcm_usbg_tpg_show_nexus(
        struct se_portal_group *se_tpg,
        char *page)
{
    struct usbg_tpg *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);
    struct tcm_usbg_nexus *tv_nexus;
    ssize_t ret;

    mutex_lock(&tpg->tpg_mutex);
    tv_nexus = tpg->tpg_nexus;
    if (!tv_nexus) {
        ret = -ENODEV;
        goto out;
    }
    ret = snprintf(page, PAGE_SIZE, "%s\n",
            tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
out:
    mutex_unlock(&tpg->tpg_mutex);
    return ret;
}

static int tcm_usbg_make_nexus(struct usbg_tpg *tpg, char *name)
{
    struct se_portal_group *se_tpg;
    struct tcm_usbg_nexus *tv_nexus;
    int ret;

    mutex_lock(&tpg->tpg_mutex);
    if (tpg->tpg_nexus) {
        ret = -EEXIST;
        pr_debug("tpg->tpg_nexus already exists\n");
        goto err_unlock;
    }
    se_tpg = &tpg->se_tpg;

    ret = -ENOMEM;
    tv_nexus = kzalloc(sizeof(*tv_nexus), GFP_KERNEL);
    if (!tv_nexus) {
        pr_err("Unable to allocate struct tcm_vhost_nexus\n");
        goto err_unlock;
    }
    tv_nexus->tvn_se_sess = transport_init_session();
    if (IS_ERR(tv_nexus->tvn_se_sess))
        goto err_free;

    /*
     * Since we are running in 'demo mode' this call with generate a
     * struct se_node_acl for the tcm_vhost struct se_portal_group with
     * the SCSI Initiator port name of the passed configfs group 'name'.
     */
    tv_nexus->tvn_se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
            se_tpg, name);
    if (!tv_nexus->tvn_se_sess->se_node_acl) {
        pr_debug("core_tpg_check_initiator_node_acl() failed"
                " for %s\n", name);
        goto err_session;
    }
    /*
     * Now register the TCM vHost virtual I_T Nexus as active with the
     * call to __transport_register_session()
     */
    __transport_register_session(se_tpg, tv_nexus->tvn_se_sess->se_node_acl,
            tv_nexus->tvn_se_sess, tv_nexus);
    tpg->tpg_nexus = tv_nexus;
    mutex_unlock(&tpg->tpg_mutex);
    return 0;

err_session:
    transport_free_session(tv_nexus->tvn_se_sess);
err_free:
    kfree(tv_nexus);
err_unlock:
    mutex_unlock(&tpg->tpg_mutex);
    return ret;
}

static int tcm_usbg_drop_nexus(struct usbg_tpg *tpg)
{
    struct se_session *se_sess;
    struct tcm_usbg_nexus *tv_nexus;
    int ret = -ENODEV;

    mutex_lock(&tpg->tpg_mutex);
    tv_nexus = tpg->tpg_nexus;
    if (!tv_nexus)
        goto out;

    se_sess = tv_nexus->tvn_se_sess;
    if (!se_sess)
        goto out;

    if (atomic_read(&tpg->tpg_port_count)) {
        ret = -EPERM;
        pr_err("Unable to remove Host I_T Nexus with"
                " active TPG port count: %d\n",
                atomic_read(&tpg->tpg_port_count));
        goto out;
    }

    pr_debug("Removing I_T Nexus to Initiator Port: %s\n",
            tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
    /*
     * Release the SCSI I_T Nexus to the emulated vHost Target Port
     */
    transport_deregister_session(tv_nexus->tvn_se_sess);
    tpg->tpg_nexus = NULL;

    kfree(tv_nexus);
out:
    mutex_unlock(&tpg->tpg_mutex);
    return 0;
}

static ssize_t tcm_usbg_tpg_store_nexus(
        struct se_portal_group *se_tpg,
        const char *page,
        size_t count)
{
    struct usbg_tpg *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);
    unsigned char i_port[USBG_NAMELEN], *ptr;
    int ret;

    if (!strncmp(page, "NULL", 4)) {
        ret = tcm_usbg_drop_nexus(tpg);
        return (!ret) ? count : ret;
    }
    if (strlen(page) >= USBG_NAMELEN) {
        pr_err("Emulated NAA Sas Address: %s, exceeds"
                " max: %d\n", page, USBG_NAMELEN);
        return -EINVAL;
    }
    snprintf(i_port, USBG_NAMELEN, "%s", page);

    ptr = strstr(i_port, "naa.");
    if (!ptr) {
        pr_err("Missing 'naa.' prefix\n");
        return -EINVAL;
    }

    if (i_port[strlen(i_port) - 1] == '\n')
        i_port[strlen(i_port) - 1] = '\0';

    ret = tcm_usbg_make_nexus(tpg, &i_port[4]);
    if (ret < 0)
        return ret;
    return count;
}
TF_TPG_BASE_ATTR(tcm_usbg, nexus, S_IRUGO | S_IWUSR);

static struct configfs_attribute *usbg_base_attrs[] = {
    &tcm_usbg_tpg_enable.attr,
    &tcm_usbg_tpg_nexus.attr,
    NULL,
};

static int usbg_port_link(struct se_portal_group *se_tpg, struct se_lun *lun)
{
    struct usbg_tpg *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);

    atomic_inc(&tpg->tpg_port_count);
    smp_mb__after_atomic_inc();
    return 0;
}

static void usbg_port_unlink(struct se_portal_group *se_tpg,
        struct se_lun *se_lun)
{
    struct usbg_tpg *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);

    atomic_dec(&tpg->tpg_port_count);
    smp_mb__after_atomic_dec();
}

static int usbg_check_stop_free(struct se_cmd *se_cmd)
{
    struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
            se_cmd);

    kref_put(&cmd->ref, usbg_cmd_release);
    return 1;
}

static struct target_core_fabric_ops usbg_ops = {
    .get_fabric_name        = usbg_get_fabric_name,
    .get_fabric_proto_ident     = usbg_get_fabric_proto_ident,
    .tpg_get_wwn            = usbg_get_fabric_wwn,
    .tpg_get_tag            = usbg_get_tag,
    .tpg_get_default_depth      = usbg_get_default_depth,
    .tpg_get_pr_transport_id    = usbg_get_pr_transport_id,
    .tpg_get_pr_transport_id_len    = usbg_get_pr_transport_id_len,
    .tpg_parse_pr_out_transport_id  = usbg_parse_pr_out_transport_id,
    .tpg_check_demo_mode        = usbg_check_true,
    .tpg_check_demo_mode_cache  = usbg_check_false,
    .tpg_check_demo_mode_write_protect = usbg_check_false,
    .tpg_check_prod_mode_write_protect = usbg_check_false,
    .tpg_alloc_fabric_acl       = usbg_alloc_fabric_acl,
    .tpg_release_fabric_acl     = usbg_release_fabric_acl,
    .tpg_get_inst_index     = usbg_tpg_get_inst_index,
    .release_cmd            = usbg_release_cmd,
    .shutdown_session       = usbg_shutdown_session,
    .close_session          = usbg_close_session,
    .sess_get_index         = usbg_sess_get_index,
    .sess_get_initiator_sid     = NULL,
    .write_pending          = usbg_send_write_request,
    .write_pending_status       = usbg_write_pending_status,
    .set_default_node_attributes    = usbg_set_default_node_attrs,
    .get_task_tag           = usbg_get_task_tag,
    .get_cmd_state          = usbg_get_cmd_state,
    .queue_data_in          = usbg_send_read_response,
    .queue_status           = usbg_send_status_response,
    .queue_tm_rsp           = usbg_queue_tm_rsp,
    .check_stop_free        = usbg_check_stop_free,

    .fabric_make_wwn        = usbg_make_tport,
    .fabric_drop_wwn        = usbg_drop_tport,
    .fabric_make_tpg        = usbg_make_tpg,
    .fabric_drop_tpg        = usbg_drop_tpg,
    .fabric_post_link       = usbg_port_link,
    .fabric_pre_unlink      = usbg_port_unlink,
    .fabric_make_np         = NULL,
    .fabric_drop_np         = NULL,
    .fabric_make_nodeacl        = usbg_make_nodeacl,
    .fabric_drop_nodeacl        = usbg_drop_nodeacl,
};

static int usbg_register_configfs(void)
{
    struct target_fabric_configfs *fabric;
    int ret;

    fabric = target_fabric_configfs_init(THIS_MODULE, "usb_gadget");
    if (IS_ERR(fabric)) {
        printk(KERN_ERR "target_fabric_configfs_init() failed\n");
        return PTR_ERR(fabric);
    }

    fabric->tf_ops = usbg_ops;
    TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = usbg_wwn_attrs;
    TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = usbg_base_attrs;
    TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_base_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_param_cit.ct_attrs = NULL;
    ret = target_fabric_configfs_register(fabric);
    if (ret < 0) {
        printk(KERN_ERR "target_fabric_configfs_register() failed"
                " for usb-gadget\n");
        return ret;
    }
    usbg_fabric_configfs = fabric;
    return 0;
};

static void usbg_deregister_configfs(void)
{
    if (!(usbg_fabric_configfs))
        return;

    target_fabric_configfs_deregister(usbg_fabric_configfs);
    usbg_fabric_configfs = NULL;
};

/* Start gadget.c code */

static struct usb_interface_descriptor bot_intf_desc = {
    .bLength =              sizeof(bot_intf_desc),
    .bDescriptorType =      USB_DT_INTERFACE,
    .bNumEndpoints =        2,
    .bAlternateSetting =    USB_G_ALT_INT_BBB,
    .bInterfaceClass =      USB_CLASS_MASS_STORAGE,
    .bInterfaceSubClass =   USB_SC_SCSI,
    .bInterfaceProtocol =   USB_PR_BULK,
};

static struct usb_interface_descriptor uasp_intf_desc = {
    .bLength =      sizeof(uasp_intf_desc),
    .bDescriptorType =  USB_DT_INTERFACE,
    .bNumEndpoints =    4,
    .bAlternateSetting =    USB_G_ALT_INT_UAS,
    .bInterfaceClass =  USB_CLASS_MASS_STORAGE,
    .bInterfaceSubClass =   USB_SC_SCSI,
    .bInterfaceProtocol =   USB_PR_UAS,
};

static struct usb_endpoint_descriptor uasp_bi_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512),
};

static struct usb_endpoint_descriptor uasp_fs_bi_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
};

static struct usb_pipe_usage_descriptor uasp_bi_pipe_desc = {
    .bLength =      sizeof(uasp_bi_pipe_desc),
    .bDescriptorType =  USB_DT_PIPE_USAGE,
    .bPipeID =      DATA_IN_PIPE_ID,
};

static struct usb_endpoint_descriptor uasp_ss_bi_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor uasp_bi_ep_comp_desc = {
    .bLength =      sizeof(uasp_bi_ep_comp_desc),
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,
    .bMaxBurst =        0,
    .bmAttributes =     UASP_SS_EP_COMP_LOG_STREAMS,
    .wBytesPerInterval =    0,
};

static struct usb_ss_ep_comp_descriptor bot_bi_ep_comp_desc = {
    .bLength =      sizeof(bot_bi_ep_comp_desc),
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,
    .bMaxBurst =        0,
};

static struct usb_endpoint_descriptor uasp_bo_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512),
};

static struct usb_endpoint_descriptor uasp_fs_bo_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
};

static struct usb_pipe_usage_descriptor uasp_bo_pipe_desc = {
    .bLength =      sizeof(uasp_bo_pipe_desc),
    .bDescriptorType =  USB_DT_PIPE_USAGE,
    .bPipeID =      DATA_OUT_PIPE_ID,
};

static struct usb_endpoint_descriptor uasp_ss_bo_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(0x400),
};

static struct usb_ss_ep_comp_descriptor uasp_bo_ep_comp_desc = {
    .bLength =      sizeof(uasp_bo_ep_comp_desc),
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,
    .bmAttributes =     UASP_SS_EP_COMP_LOG_STREAMS,
};

static struct usb_ss_ep_comp_descriptor bot_bo_ep_comp_desc = {
    .bLength =      sizeof(bot_bo_ep_comp_desc),
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,
};

static struct usb_endpoint_descriptor uasp_status_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512),
};

static struct usb_endpoint_descriptor uasp_fs_status_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
};

static struct usb_pipe_usage_descriptor uasp_status_pipe_desc = {
    .bLength =      sizeof(uasp_status_pipe_desc),
    .bDescriptorType =  USB_DT_PIPE_USAGE,
    .bPipeID =      STATUS_PIPE_ID,
};

static struct usb_endpoint_descriptor uasp_ss_status_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_IN,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor uasp_status_in_ep_comp_desc = {
    .bLength =      sizeof(uasp_status_in_ep_comp_desc),
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,
    .bmAttributes =     UASP_SS_EP_COMP_LOG_STREAMS,
};

static struct usb_endpoint_descriptor uasp_cmd_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(512),
};

static struct usb_endpoint_descriptor uasp_fs_cmd_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
};

static struct usb_pipe_usage_descriptor uasp_cmd_pipe_desc = {
    .bLength =      sizeof(uasp_cmd_pipe_desc),
    .bDescriptorType =  USB_DT_PIPE_USAGE,
    .bPipeID =      CMD_PIPE_ID,
};

static struct usb_endpoint_descriptor uasp_ss_cmd_desc = {
    .bLength =      USB_DT_ENDPOINT_SIZE,
    .bDescriptorType =  USB_DT_ENDPOINT,
    .bEndpointAddress = USB_DIR_OUT,
    .bmAttributes =     USB_ENDPOINT_XFER_BULK,
    .wMaxPacketSize =   cpu_to_le16(1024),
};

static struct usb_ss_ep_comp_descriptor uasp_cmd_comp_desc = {
    .bLength =      sizeof(uasp_cmd_comp_desc),
    .bDescriptorType =  USB_DT_SS_ENDPOINT_COMP,
};

static struct usb_descriptor_header *uasp_fs_function_desc[] = {
    (struct usb_descriptor_header *) &bot_intf_desc,
    (struct usb_descriptor_header *) &uasp_fs_bi_desc,
    (struct usb_descriptor_header *) &uasp_fs_bo_desc,

    (struct usb_descriptor_header *) &uasp_intf_desc,
    (struct usb_descriptor_header *) &uasp_fs_bi_desc,
    (struct usb_descriptor_header *) &uasp_bi_pipe_desc,
    (struct usb_descriptor_header *) &uasp_fs_bo_desc,
    (struct usb_descriptor_header *) &uasp_bo_pipe_desc,
    (struct usb_descriptor_header *) &uasp_fs_status_desc,
    (struct usb_descriptor_header *) &uasp_status_pipe_desc,
    (struct usb_descriptor_header *) &uasp_fs_cmd_desc,
    (struct usb_descriptor_header *) &uasp_cmd_pipe_desc,
};

static struct usb_descriptor_header *uasp_hs_function_desc[] = {
    (struct usb_descriptor_header *) &bot_intf_desc,
    (struct usb_descriptor_header *) &uasp_bi_desc,
    (struct usb_descriptor_header *) &uasp_bo_desc,

    (struct usb_descriptor_header *) &uasp_intf_desc,
    (struct usb_descriptor_header *) &uasp_bi_desc,
    (struct usb_descriptor_header *) &uasp_bi_pipe_desc,
    (struct usb_descriptor_header *) &uasp_bo_desc,
    (struct usb_descriptor_header *) &uasp_bo_pipe_desc,
    (struct usb_descriptor_header *) &uasp_status_desc,
    (struct usb_descriptor_header *) &uasp_status_pipe_desc,
    (struct usb_descriptor_header *) &uasp_cmd_desc,
    (struct usb_descriptor_header *) &uasp_cmd_pipe_desc,
    NULL,
};

static struct usb_descriptor_header *uasp_ss_function_desc[] = {
    (struct usb_descriptor_header *) &bot_intf_desc,
    (struct usb_descriptor_header *) &uasp_ss_bi_desc,
    (struct usb_descriptor_header *) &bot_bi_ep_comp_desc,
    (struct usb_descriptor_header *) &uasp_ss_bo_desc,
    (struct usb_descriptor_header *) &bot_bo_ep_comp_desc,

    (struct usb_descriptor_header *) &uasp_intf_desc,
    (struct usb_descriptor_header *) &uasp_ss_bi_desc,
    (struct usb_descriptor_header *) &uasp_bi_ep_comp_desc,
    (struct usb_descriptor_header *) &uasp_bi_pipe_desc,
    (struct usb_descriptor_header *) &uasp_ss_bo_desc,
    (struct usb_descriptor_header *) &uasp_bo_ep_comp_desc,
    (struct usb_descriptor_header *) &uasp_bo_pipe_desc,
    (struct usb_descriptor_header *) &uasp_ss_status_desc,
    (struct usb_descriptor_header *) &uasp_status_in_ep_comp_desc,
    (struct usb_descriptor_header *) &uasp_status_pipe_desc,
    (struct usb_descriptor_header *) &uasp_ss_cmd_desc,
    (struct usb_descriptor_header *) &uasp_cmd_comp_desc,
    (struct usb_descriptor_header *) &uasp_cmd_pipe_desc,
    NULL,
};

#define UAS_VENDOR_ID   0x0525  /* NetChip */
#define UAS_PRODUCT_ID  0xa4a5  /* Linux-USB File-backed Storage Gadget */

static struct usb_device_descriptor usbg_device_desc = {
    .bLength =      sizeof(usbg_device_desc),
    .bDescriptorType =  USB_DT_DEVICE,
    .bcdUSB =       cpu_to_le16(0x0200),
    .bDeviceClass =     USB_CLASS_PER_INTERFACE,
    .idVendor =     cpu_to_le16(UAS_VENDOR_ID),
    .idProduct =        cpu_to_le16(UAS_PRODUCT_ID),
    .bNumConfigurations =   1,
};

static struct usb_string    usbg_us_strings[] = {
    [USB_GADGET_MANUFACTURER_IDX].s = "Target Manufactor",
    [USB_GADGET_PRODUCT_IDX].s  = "Target Product",
    [USB_GADGET_SERIAL_IDX].s   = "000000000001",
    [USB_G_STR_CONFIG].s        = "default config",
    [USB_G_STR_INT_UAS].s       = "USB Attached SCSI",
    [USB_G_STR_INT_BBB].s       = "Bulk Only Transport",
    { },
};

static struct usb_gadget_strings usbg_stringtab = {
    .language = 0x0409,
    .strings = usbg_us_strings,
};

static struct usb_gadget_strings *usbg_strings[] = {
    &usbg_stringtab,
    NULL,
};

static int guas_unbind(struct usb_composite_dev *cdev)
{
    return 0;
}

static struct usb_configuration usbg_config_driver = {
    .label                  = "Linux Target",
    .bConfigurationValue    = 1,
    .bmAttributes           = USB_CONFIG_ATT_SELFPOWER,
};

static void give_back_ep(struct usb_ep **pep)
{
    struct usb_ep *ep = *pep;
    if (!ep)
        return;
    ep->driver_data = NULL;
}

static int usbg_bind(struct usb_configuration *c, struct usb_function *f)
{
    struct f_uas        *fu = to_f_uas(f);
    struct usb_gadget   *gadget = c->cdev->gadget;
    struct usb_ep       *ep;
    int         iface;

    iface = usb_interface_id(c, f);
    if (iface < 0)
        return iface;

    bot_intf_desc.bInterfaceNumber = iface;
    uasp_intf_desc.bInterfaceNumber = iface;
    fu->iface = iface;
    ep = usb_ep_autoconfig_ss(gadget, &uasp_ss_bi_desc,
            &uasp_bi_ep_comp_desc);
    if (!ep)
        goto ep_fail;

    ep->driver_data = fu;
    fu->ep_in = ep;

    ep = usb_ep_autoconfig_ss(gadget, &uasp_ss_bo_desc,
            &uasp_bo_ep_comp_desc);
    if (!ep)
        goto ep_fail;
    ep->driver_data = fu;
    fu->ep_out = ep;

    ep = usb_ep_autoconfig_ss(gadget, &uasp_ss_status_desc,
            &uasp_status_in_ep_comp_desc);
    if (!ep)
        goto ep_fail;
    ep->driver_data = fu;
    fu->ep_status = ep;

    ep = usb_ep_autoconfig_ss(gadget, &uasp_ss_cmd_desc,
            &uasp_cmd_comp_desc);
    if (!ep)
        goto ep_fail;
    ep->driver_data = fu;
    fu->ep_cmd = ep;

    /* Assume endpoint addresses are the same for both speeds */
    uasp_bi_desc.bEndpointAddress = uasp_ss_bi_desc.bEndpointAddress;
    uasp_bo_desc.bEndpointAddress = uasp_ss_bo_desc.bEndpointAddress;
    uasp_status_desc.bEndpointAddress =
        uasp_ss_status_desc.bEndpointAddress;
    uasp_cmd_desc.bEndpointAddress = uasp_ss_cmd_desc.bEndpointAddress;

    uasp_fs_bi_desc.bEndpointAddress = uasp_ss_bi_desc.bEndpointAddress;
    uasp_fs_bo_desc.bEndpointAddress = uasp_ss_bo_desc.bEndpointAddress;
    uasp_fs_status_desc.bEndpointAddress =
        uasp_ss_status_desc.bEndpointAddress;
    uasp_fs_cmd_desc.bEndpointAddress = uasp_ss_cmd_desc.bEndpointAddress;

    return 0;
ep_fail:
    pr_err("Can't claim all required eps\n");

    give_back_ep(&fu->ep_in);
    give_back_ep(&fu->ep_out);
    give_back_ep(&fu->ep_status);
    give_back_ep(&fu->ep_cmd);
    return -ENOTSUPP;
}

static void usbg_unbind(struct usb_configuration *c, struct usb_function *f)
{
    struct f_uas *fu = to_f_uas(f);

    kfree(fu);
}

struct guas_setup_wq {
    struct work_struct work;
    struct f_uas *fu;
    unsigned int alt;
};

static void usbg_delayed_set_alt(struct work_struct *wq)
{
    struct guas_setup_wq *work = container_of(wq, struct guas_setup_wq,
            work);
    struct f_uas *fu = work->fu;
    int alt = work->alt;

    kfree(work);

    if (fu->flags & USBG_IS_BOT)
        bot_cleanup_old_alt(fu);
    if (fu->flags & USBG_IS_UAS)
        uasp_cleanup_old_alt(fu);

    if (alt == USB_G_ALT_INT_BBB)
        bot_set_alt(fu);
    else if (alt == USB_G_ALT_INT_UAS)
        uasp_set_alt(fu);
    usb_composite_setup_continue(fu->function.config->cdev);
}

static int usbg_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
    struct f_uas *fu = to_f_uas(f);

    if ((alt == USB_G_ALT_INT_BBB) || (alt == USB_G_ALT_INT_UAS)) {
        struct guas_setup_wq *work;

        work = kmalloc(sizeof(*work), GFP_ATOMIC);
        if (!work)
            return -ENOMEM;
        INIT_WORK(&work->work, usbg_delayed_set_alt);
        work->fu = fu;
        work->alt = alt;
        schedule_work(&work->work);
        return USB_GADGET_DELAYED_STATUS;
    }
    return -EOPNOTSUPP;
}

static void usbg_disable(struct usb_function *f)
{
    struct f_uas *fu = to_f_uas(f);

    if (fu->flags & USBG_IS_UAS)
        uasp_cleanup_old_alt(fu);
    else if (fu->flags & USBG_IS_BOT)
        bot_cleanup_old_alt(fu);
    fu->flags = 0;
}

static int usbg_setup(struct usb_function *f,
        const struct usb_ctrlrequest *ctrl)
{
    struct f_uas *fu = to_f_uas(f);

    if (!(fu->flags & USBG_IS_BOT))
        return -EOPNOTSUPP;

    return usbg_bot_setup(f, ctrl);
}

static int usbg_cfg_bind(struct usb_configuration *c)
{
    struct f_uas *fu;
    int ret;

    fu = kzalloc(sizeof(*fu), GFP_KERNEL);
    if (!fu)
        return -ENOMEM;
    fu->function.name = "Target Function";
    fu->function.descriptors = uasp_fs_function_desc;
    fu->function.hs_descriptors = uasp_hs_function_desc;
    fu->function.ss_descriptors = uasp_ss_function_desc;
    fu->function.bind = usbg_bind;
    fu->function.unbind = usbg_unbind;
    fu->function.set_alt = usbg_set_alt;
    fu->function.setup = usbg_setup;
    fu->function.disable = usbg_disable;
    fu->tpg = the_only_tpg_I_currently_have;

    bot_intf_desc.iInterface = usbg_us_strings[USB_G_STR_INT_BBB].id;
    uasp_intf_desc.iInterface = usbg_us_strings[USB_G_STR_INT_UAS].id;

    ret = usb_add_function(c, &fu->function);
    if (ret)
        goto err;

    return 0;
err:
    kfree(fu);
    return ret;
}

static int usb_target_bind(struct usb_composite_dev *cdev)
{
    int ret;

    ret = usb_string_ids_tab(cdev, usbg_us_strings);
    if (ret)
        return ret;

    usbg_device_desc.iManufacturer =
        usbg_us_strings[USB_GADGET_MANUFACTURER_IDX].id;
    usbg_device_desc.iProduct = usbg_us_strings[USB_GADGET_PRODUCT_IDX].id;
    usbg_device_desc.iSerialNumber =
        usbg_us_strings[USB_GADGET_SERIAL_IDX].id;
    usbg_config_driver.iConfiguration =
        usbg_us_strings[USB_G_STR_CONFIG].id;

    ret = usb_add_config(cdev, &usbg_config_driver,
            usbg_cfg_bind);
    if (ret)
        return ret;
    usb_composite_overwrite_options(cdev, &coverwrite);
    return 0;
}

static __refdata struct usb_composite_driver usbg_driver = {
    .name           = "g_target",
    .dev            = &usbg_device_desc,
    .strings        = usbg_strings,
    .max_speed      = USB_SPEED_SUPER,
    .bind       = usb_target_bind,
    .unbind         = guas_unbind,
};

static int usbg_attach(struct usbg_tpg *tpg)
{
    return usb_composite_probe(&usbg_driver);
}

static void usbg_detach(struct usbg_tpg *tpg)
{
    usb_composite_unregister(&usbg_driver);
}

static int __init usb_target_gadget_init(void)
{
    int ret;

    ret = usbg_register_configfs();
    return ret;
}
module_init(usb_target_gadget_init);

static void __exit usb_target_gadget_exit(void)
{
    usbg_deregister_configfs();
}
module_exit(usb_target_gadget_exit);

MODULE_AUTHOR("Sebastian Andrzej Siewior <[email protected]>");
MODULE_DESCRIPTION("usb-gadget fabric");
MODULE_LICENSE("GPL v2");