gadget/function/f_tcm.c

// SPDX-License-Identifier: GPL-2.0
/* 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>
 */
#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_tcq.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <linux/unaligned.h>

#include "tcm.h"
#include "u_tcm.h"
#include "configfs.h"

#define TPG_INSTANCES		1

struct tpg_instance {
	struct usb_function_instance	*func_inst;
	struct usbg_tpg			*tpg;
};

static struct tpg_instance tpg_instances[TPG_INSTANCES];

static DEFINE_MUTEX(tpg_instances_lock);

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

/* 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[0].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;

	transport_generic_free_cmd(&cmd->se_cmd, 0);
	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;
	unsigned int csw_stat;

	csw_stat = cmd->csw_code;
	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[0].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;
	int ret;

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

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

	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[0].req = usb_ep_alloc_request(fu->ep_out, GFP_KERNEL);
	if (!fu->cmd[0].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[0].buf = kmalloc(fu->ep_out->maxpacket, GFP_KERNEL);
	if (!fu->cmd[0].buf)
		goto err_buf;

	fu->cmd[0].req->complete = bot_cmd_complete;
	fu->cmd[0].req->buf = fu->cmd[0].buf;
	fu->cmd[0].req->length = fu->ep_out->maxpacket;
	fu->cmd[0].req->context = fu;

	ret = bot_enqueue_cmd_cbw(fu);
	if (ret)
		goto err_queue;
	return 0;
err_queue:
	kfree(fu->cmd[0].buf);
	fu->cmd[0].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[0].req);
	fu->cmd[0].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;
}

static 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[0].req);
	usb_ep_free_request(fu->ep_in, fu->bot_status.req);

	kfree(fu->cmd[0].buf);

	fu->bot_req_in = NULL;
	fu->bot_req_out = NULL;
	fu->cmd[0].req = NULL;
	fu->bot_status.req = NULL;
	fu->cmd[0].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_and_alt(gadget, f, fu->ep_in, USB_G_ALT_INT_BBB);
	ret = usb_ep_enable(fu->ep_in);
	if (ret)
		goto err_b_in;

	config_ep_by_speed_and_alt(gadget, f, fu->ep_out, USB_G_ALT_INT_BBB);
	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;
		}
		luns--;
		if (luns > US_BULK_MAX_LUN_LIMIT) {
			pr_info_once("Limiting the number of luns to 16\n");
			luns = US_BULK_MAX_LUN_LIMIT;
		}
		ret_lun = cdev->req->buf;
		*ret_lun = luns;
		cdev->req->length = 1;
		return usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);

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

	for (i = 0; i < USBG_NUM_CMDS; i++) {
		usb_ep_free_request(fu->ep_cmd, fu->cmd[i].req);
		kfree(fu->cmd[i].buf);
		fu->cmd[i].req = NULL;
		fu->cmd[i].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 < USBG_NUM_CMDS; 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 = &fu->stream[se_cmd->map_tag];

	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->is_last = 1;
	stream->req_in->stream_id = cmd->tag;
	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->fu->stream[se_cmd->map_tag];

	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->is_last = 1;
	stream->req_status->stream_id = cmd->tag;
	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 f_uas *fu = cmd->fu;
	struct uas_stream *stream = &fu->stream[cmd->se_cmd.map_tag];
	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:
		transport_generic_free_cmd(&cmd->se_cmd, 0);
		usb_ep_queue(fu->ep_cmd, cmd->req, GFP_ATOMIC);

		break;

	default:
		BUG();
	}
	return;

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

static int uasp_send_status_response(struct usbg_cmd *cmd)
{
	struct f_uas *fu = cmd->fu;
	struct uas_stream *stream = &fu->stream[cmd->se_cmd.map_tag];
	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 = &fu->stream[cmd->se_cmd.map_tag];
	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 = &fu->stream[se_cmd->map_tag];
	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 *, struct usb_request *);

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

	if (req->status == -ESHUTDOWN)
		return;

	if (req->status < 0) {
		usb_ep_queue(fu->ep_cmd, req, GFP_ATOMIC);
		return;
	}

	usbg_submit_command(fu, req);
}

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_out, stream->req_out);
	stream->req_out = NULL;
err_out:
	usb_ep_free_request(fu->ep_in, stream->req_in);
	stream->req_in = NULL;
out:
	return -ENOMEM;
}

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

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

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

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

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

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

	for (i = 0; i < USBG_NUM_CMDS; i++) {
		ret = uasp_alloc_cmd(fu, i);
		if (ret)
			goto err_free_stream;

		ret = usb_ep_queue(fu->ep_cmd, fu->cmd[i].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_and_alt(gadget, f, fu->ep_in, USB_G_ALT_INT_UAS);
	ret = usb_ep_enable(fu->ep_in);
	if (ret)
		goto err_b_in;

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

	config_ep_by_speed_and_alt(gadget, f, fu->ep_cmd, USB_G_ALT_INT_UAS);
	ret = usb_ep_enable(fu->ep_cmd);
	if (ret)
		goto err_cmd;
	config_ep_by_speed_and_alt(gadget, f, fu->ep_status, USB_G_ALT_INT_UAS);
	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_16:
	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:
#define CMD_DIR_MSG "target: Unknown data direction for SCSI Opcode 0x%02x\n"
		pr_warn(CMD_DIR_MSG, cdb[0]);
#undef CMD_DIR_MSG
		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:
	target_put_sess_cmd(se_cmd);
	transport_generic_free_cmd(&cmd->se_cmd, 0);
}

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->is_last = 1;
	req->stream_id = cmd->tag;
	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, flags = (TARGET_SCF_UNKNOWN_SIZE | TARGET_SCF_ACK_KREF);

	se_cmd = &cmd->se_cmd;
	tpg = cmd->fu->tpg;
	tv_nexus = tpg->tpg_nexus;
	dir = get_cmd_dir(cmd->cmd_buf);
	if (dir < 0) {
		__target_init_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,
				  cmd->unpacked_lun, NULL);
		goto out;
	}

	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, flags);
	return;

out:
	transport_send_check_condition_and_sense(se_cmd,
			TCM_UNSUPPORTED_SCSI_OPCODE, 0);
}

static struct usbg_cmd *usbg_get_cmd(struct f_uas *fu,
		struct tcm_usbg_nexus *tv_nexus, u32 scsi_tag)
{
	struct se_session *se_sess = tv_nexus->tvn_se_sess;
	struct usbg_cmd *cmd;
	int tag, cpu;

	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
	if (tag < 0)
		return ERR_PTR(-ENOMEM);

	cmd = &((struct usbg_cmd *)se_sess->sess_cmd_map)[tag];
	memset(cmd, 0, sizeof(*cmd));
	cmd->se_cmd.map_tag = tag;
	cmd->se_cmd.map_cpu = cpu;
	cmd->se_cmd.tag = cmd->tag = scsi_tag;
	cmd->fu = fu;

	return cmd;
}

static void usbg_release_cmd(struct se_cmd *);

static int usbg_submit_command(struct f_uas *fu, struct usb_request *req)
{
	struct command_iu *cmd_iu = req->buf;
	struct usbg_cmd *cmd;
	struct usbg_tpg *tpg = fu->tpg;
	struct tcm_usbg_nexus *tv_nexus;
	u32 cmd_len;
	u16 scsi_tag;

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

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

	cmd_len = (cmd_iu->len & ~0x3) + 16;
	if (cmd_len > USBG_MAX_CMD)
		return -EINVAL;

	scsi_tag = be16_to_cpup(&cmd_iu->tag);
	cmd = usbg_get_cmd(fu, tv_nexus, scsi_tag);
	if (IS_ERR(cmd)) {
		pr_err("usbg_get_cmd failed\n");
		return -ENOMEM;
	}
	memcpy(cmd->cmd_buf, cmd_iu->cdb, cmd_len);

	switch (cmd_iu->prio_attr & 0x7) {
	case UAS_HEAD_TAG:
		cmd->prio_attr = TCM_HEAD_TAG;
		break;
	case UAS_ORDERED_TAG:
		cmd->prio_attr = TCM_ORDERED_TAG;
		break;
	case UAS_ACA:
		cmd->prio_attr = TCM_ACA_TAG;
		break;
	default:
		pr_debug_once("Unsupported prio_attr: %02x.\n",
				cmd_iu->prio_attr);
		fallthrough;
	case UAS_SIMPLE_TAG:
		cmd->prio_attr = TCM_SIMPLE_TAG;
		break;
	}

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

	INIT_WORK(&cmd->work, usbg_cmd_work);
	queue_work(tpg->workqueue, &cmd->work);

	return 0;
}

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) {
		__target_init_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,
				  cmd->unpacked_lun, NULL);
		goto out;
	}

	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);
	return;

out:
	transport_send_check_condition_and_sense(se_cmd,
				TCM_UNSUPPORTED_SCSI_OPCODE, 0);
}

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 = fu->tpg;
	struct tcm_usbg_nexus *tv_nexus;
	u32 cmd_len;

	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;

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

	cmd = usbg_get_cmd(fu, tv_nexus, cbw->Tag);
	if (IS_ERR(cmd)) {
		pr_err("usbg_get_cmd failed\n");
		return -ENOMEM;
	}
	memcpy(cmd->cmd_buf, cbw->CDB, cmd_len);

	cmd->bot_tag = cbw->Tag;
	cmd->prio_attr = TCM_SIMPLE_TAG;
	cmd->unpacked_lun = cbw->Lun;
	cmd->is_read = cbw->Flags & US_BULK_FLAG_IN ? 1 : 0;
	cmd->data_len = le32_to_cpu(cbw->DataTransferLength);
	cmd->se_cmd.tag = le32_to_cpu(cmd->bot_tag);

	INIT_WORK(&cmd->work, bot_cmd_work);
	queue_work(tpg->workqueue, &cmd->work);

	return 0;
}

/* Start fabric.c code */

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

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 void usbg_release_cmd(struct se_cmd *se_cmd)
{
	struct usbg_cmd *cmd = container_of(se_cmd, struct usbg_cmd,
			se_cmd);
	struct se_session *se_sess = se_cmd->se_sess;

	kfree(cmd->data_buf);
	target_free_tag(se_sess, se_cmd);
}

static void usbg_queue_tm_rsp(struct se_cmd *se_cmd)
{
}

static void usbg_aborted_task(struct se_cmd *se_cmd)
{
}

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 int usbg_init_nodeacl(struct se_node_acl *se_nacl, const char *name)
{
	if (!usbg_check_wwn(name))
		return -EINVAL;
	return 0;
}

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

	if (strstr(name, "tpgt_") != name)
		return ERR_PTR(-EINVAL);
	if (kstrtoul(name + 5, 0, &tpgt) || tpgt > UINT_MAX)
		return ERR_PTR(-EINVAL);
	ret = -ENODEV;
	mutex_lock(&tpg_instances_lock);
	for (i = 0; i < TPG_INSTANCES; ++i)
		if (tpg_instances[i].func_inst && !tpg_instances[i].tpg)
			break;
	if (i == TPG_INSTANCES)
		goto unlock_inst;

	opts = container_of(tpg_instances[i].func_inst, struct f_tcm_opts,
		func_inst);
	mutex_lock(&opts->dep_lock);
	if (!opts->ready)
		goto unlock_dep;

	if (opts->has_dep) {
		if (!try_module_get(opts->dependent))
			goto unlock_dep;
	} else {
		ret = configfs_depend_item_unlocked(
			wwn->wwn_group.cg_subsys,
			&opts->func_inst.group.cg_item);
		if (ret)
			goto unlock_dep;
	}

	tpg = kzalloc(sizeof(struct usbg_tpg), GFP_KERNEL);
	ret = -ENOMEM;
	if (!tpg)
		goto unref_dep;
	mutex_init(&tpg->tpg_mutex);
	atomic_set(&tpg->tpg_port_count, 0);
	tpg->workqueue = alloc_workqueue("tcm_usb_gadget",
					 WQ_UNBOUND, WQ_UNBOUND_MAX_ACTIVE);
	if (!tpg->workqueue)
		goto free_tpg;

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

	/*
	 * SPC doesn't assign a protocol identifier for USB-SCSI, so we
	 * pretend to be SAS..
	 */
	ret = core_tpg_register(wwn, &tpg->se_tpg, SCSI_PROTOCOL_SAS);
	if (ret < 0)
		goto free_workqueue;

	tpg_instances[i].tpg = tpg;
	tpg->fi = tpg_instances[i].func_inst;
	mutex_unlock(&opts->dep_lock);
	mutex_unlock(&tpg_instances_lock);
	return &tpg->se_tpg;

free_workqueue:
	destroy_workqueue(tpg->workqueue);
free_tpg:
	kfree(tpg);
unref_dep:
	if (opts->has_dep)
		module_put(opts->dependent);
	else
		configfs_undepend_item_unlocked(&opts->func_inst.group.cg_item);
unlock_dep:
	mutex_unlock(&opts->dep_lock);
unlock_inst:
	mutex_unlock(&tpg_instances_lock);

	return ERR_PTR(ret);
}

static int tcm_usbg_drop_nexus(struct usbg_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);
	unsigned i;
	struct f_tcm_opts *opts;

	tcm_usbg_drop_nexus(tpg);
	core_tpg_deregister(se_tpg);
	destroy_workqueue(tpg->workqueue);

	mutex_lock(&tpg_instances_lock);
	for (i = 0; i < TPG_INSTANCES; ++i)
		if (tpg_instances[i].tpg == tpg)
			break;
	if (i < TPG_INSTANCES) {
		tpg_instances[i].tpg = NULL;
		opts = container_of(tpg_instances[i].func_inst,
			struct f_tcm_opts, func_inst);
		mutex_lock(&opts->dep_lock);
		if (opts->has_dep)
			module_put(opts->dependent);
		else
			configfs_undepend_item_unlocked(
				&opts->func_inst.group.cg_item);
		mutex_unlock(&opts->dep_lock);
	}
	mutex_unlock(&tpg_instances_lock);

	kfree(tpg);
}

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))
		return ERR_PTR(-ENOMEM);

	tport->tport_wwpn = wwpn;
	snprintf(tport->tport_name, sizeof(tport->tport_name), "%s", 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_version_show(struct config_item *item,  char *page)
{
	return sprintf(page, "usb-gadget fabric module\n");
}

CONFIGFS_ATTR_RO(usbg_wwn_, version);

static struct configfs_attribute *usbg_wwn_attrs[] = {
	&usbg_wwn_attr_version,
	NULL,
};

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

static int usbg_enable_tpg(struct se_portal_group *se_tpg, bool enable)
{
	struct usbg_tpg  *tpg = container_of(se_tpg, struct usbg_tpg, se_tpg);
	int ret = 0;

	if (enable)
		ret = usbg_attach(tpg);
	else
		usbg_detach(tpg);
	if (ret)
		return ret;

	tpg->gadget_connect = enable;

	return 0;
}

static ssize_t tcm_usbg_tpg_nexus_show(struct config_item *item, char *page)
{
	struct se_portal_group *se_tpg = to_tpg(item);
	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 = sysfs_emit(page, "%s\n",
			 tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
out:
	mutex_unlock(&tpg->tpg_mutex);
	return ret;
}

static int usbg_alloc_sess_cb(struct se_portal_group *se_tpg,
			      struct se_session *se_sess, void *p)
{
	struct usbg_tpg *tpg = container_of(se_tpg,
				struct usbg_tpg, se_tpg);

	tpg->tpg_nexus = p;
	return 0;
}

static int tcm_usbg_make_nexus(struct usbg_tpg *tpg, char *name)
{
	struct tcm_usbg_nexus *tv_nexus;
	int ret = 0;

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

	tv_nexus = kzalloc(sizeof(*tv_nexus), GFP_KERNEL);
	if (!tv_nexus) {
		ret = -ENOMEM;
		goto out_unlock;
	}

	tv_nexus->tvn_se_sess = target_setup_session(&tpg->se_tpg,
						     USB_G_DEFAULT_SESSION_TAGS,
						     sizeof(struct usbg_cmd),
						     TARGET_PROT_NORMAL, name,
						     tv_nexus, usbg_alloc_sess_cb);
	if (IS_ERR(tv_nexus->tvn_se_sess)) {
#define MAKE_NEXUS_MSG "core_tpg_check_initiator_node_acl() failed for %s\n"
		pr_debug(MAKE_NEXUS_MSG, name);
#undef MAKE_NEXUS_MSG
		ret = PTR_ERR(tv_nexus->tvn_se_sess);
		kfree(tv_nexus);
	}

out_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;
#define MSG "Unable to remove Host I_T Nexus with active TPG port count: %d\n"
		pr_err(MSG, atomic_read(&tpg->tpg_port_count));
#undef MSG
		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
	 */
	target_remove_session(se_sess);
	tpg->tpg_nexus = NULL;

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

static ssize_t tcm_usbg_tpg_nexus_store(struct config_item *item,
		const char *page, size_t count)
{
	struct se_portal_group *se_tpg = to_tpg(item);
	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) {

#define NEXUS_STORE_MSG "Emulated NAA Sas Address: %s, exceeds max: %d\n"
		pr_err(NEXUS_STORE_MSG, page, USBG_NAMELEN);
#undef NEXUS_STORE_MSG
		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[0]);
	if (ret < 0)
		return ret;
	return count;
}

CONFIGFS_ATTR(tcm_usbg_tpg_, nexus);

static struct configfs_attribute *usbg_base_attrs[] = {
	&tcm_usbg_tpg_attr_nexus,
	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();
	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();
}

static int usbg_check_stop_free(struct se_cmd *se_cmd)
{
	return target_put_sess_cmd(se_cmd);
}

static const struct target_core_fabric_ops usbg_ops = {
	.module				= THIS_MODULE,
	.fabric_name			= "usb_gadget",
	.tpg_get_wwn			= usbg_get_fabric_wwn,
	.tpg_get_tag			= usbg_get_tag,
	.tpg_check_demo_mode		= usbg_check_true,
	.release_cmd			= usbg_release_cmd,
	.sess_get_initiator_sid		= NULL,
	.write_pending			= usbg_send_write_request,
	.queue_data_in			= usbg_send_read_response,
	.queue_status			= usbg_send_status_response,
	.queue_tm_rsp			= usbg_queue_tm_rsp,
	.aborted_task			= usbg_aborted_task,
	.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_enable_tpg		= usbg_enable_tpg,
	.fabric_drop_tpg		= usbg_drop_tpg,
	.fabric_post_link		= usbg_port_link,
	.fabric_pre_unlink		= usbg_port_unlink,
	.fabric_init_nodeacl		= usbg_init_nodeacl,

	.tfc_wwn_attrs			= usbg_wwn_attrs,
	.tfc_tpg_base_attrs		= usbg_base_attrs,

	.default_submit_type		= TARGET_DIRECT_SUBMIT,
	.direct_submit_supp		= 1,
};

/* 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 =		15,
	.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 =		15,
};

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,
	.bMaxBurst =		15,
	.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,
	.bMaxBurst =		15,
};

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,
	NULL,
};

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,
};

static struct usb_string	tcm_us_strings[] = {
	[USB_G_STR_INT_UAS].s		= "USB Attached SCSI",
	[USB_G_STR_INT_BBB].s		= "Bulk Only Transport",
	{ },
};

static struct usb_gadget_strings tcm_stringtab = {
	.language = 0x0409,
	.strings = tcm_us_strings,
};

static struct usb_gadget_strings *tcm_strings[] = {
	&tcm_stringtab,
	NULL,
};

static int tcm_bind(struct usb_configuration *c, struct usb_function *f)
{
	struct f_uas		*fu = to_f_uas(f);
	struct usb_string	*us;
	struct usb_gadget	*gadget = c->cdev->gadget;
	struct usb_ep		*ep;
	struct f_tcm_opts	*opts;
	int			iface;
	int			ret;

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

	mutex_lock(&opts->dep_lock);
	if (!opts->can_attach) {
		mutex_unlock(&opts->dep_lock);
		return -ENODEV;
	}
	mutex_unlock(&opts->dep_lock);
	us = usb_gstrings_attach(c->cdev, tcm_strings,
		ARRAY_SIZE(tcm_us_strings));
	if (IS_ERR(us))
		return PTR_ERR(us);
	bot_intf_desc.iInterface = us[USB_G_STR_INT_BBB].id;
	uasp_intf_desc.iInterface = us[USB_G_STR_INT_UAS].id;

	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(gadget, &uasp_fs_bi_desc);
	if (!ep)
		goto ep_fail;

	fu->ep_in = ep;

	ep = usb_ep_autoconfig(gadget, &uasp_fs_bo_desc);
	if (!ep)
		goto ep_fail;
	fu->ep_out = ep;

	ep = usb_ep_autoconfig(gadget, &uasp_fs_status_desc);
	if (!ep)
		goto ep_fail;
	fu->ep_status = ep;

	ep = usb_ep_autoconfig(gadget, &uasp_fs_cmd_desc);
	if (!ep)
		goto ep_fail;
	fu->ep_cmd = ep;

	/* Assume endpoint addresses are the same for both speeds */
	uasp_bi_desc.bEndpointAddress =	uasp_fs_bi_desc.bEndpointAddress;
	uasp_bo_desc.bEndpointAddress = uasp_fs_bo_desc.bEndpointAddress;
	uasp_status_desc.bEndpointAddress =
		uasp_fs_status_desc.bEndpointAddress;
	uasp_cmd_desc.bEndpointAddress = uasp_fs_cmd_desc.bEndpointAddress;

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

	ret = usb_assign_descriptors(f, uasp_fs_function_desc,
			uasp_hs_function_desc, uasp_ss_function_desc,
			uasp_ss_function_desc);
	if (ret)
		goto ep_fail;

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

	return -ENOTSUPP;
}

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

static void tcm_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 tcm_get_alt(struct usb_function *f, unsigned intf)
{
	struct f_uas *fu = to_f_uas(f);

	if (fu->iface != intf)
		return -EOPNOTSUPP;

	if (fu->flags & USBG_IS_BOT)
		return USB_G_ALT_INT_BBB;
	else if (fu->flags & USBG_IS_UAS)
		return USB_G_ALT_INT_UAS;

	return -EOPNOTSUPP;
}

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

	if (fu->iface != intf)
		return -EOPNOTSUPP;

	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, tcm_delayed_set_alt);
		work->fu = fu;
		work->alt = alt;
		schedule_work(&work->work);
		return USB_GADGET_DELAYED_STATUS;
	}
	return -EOPNOTSUPP;
}

static void tcm_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 tcm_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 inline struct f_tcm_opts *to_f_tcm_opts(struct config_item *item)
{
	return container_of(to_config_group(item), struct f_tcm_opts,
		func_inst.group);
}

static void tcm_attr_release(struct config_item *item)
{
	struct f_tcm_opts *opts = to_f_tcm_opts(item);

	usb_put_function_instance(&opts->func_inst);
}

static struct configfs_item_operations tcm_item_ops = {
	.release		= tcm_attr_release,
};

static const struct config_item_type tcm_func_type = {
	.ct_item_ops	= &tcm_item_ops,
	.ct_owner	= THIS_MODULE,
};

static void tcm_free_inst(struct usb_function_instance *f)
{
	struct f_tcm_opts *opts;
	unsigned i;

	opts = container_of(f, struct f_tcm_opts, func_inst);

	mutex_lock(&tpg_instances_lock);
	for (i = 0; i < TPG_INSTANCES; ++i)
		if (tpg_instances[i].func_inst == f)
			break;
	if (i < TPG_INSTANCES)
		tpg_instances[i].func_inst = NULL;
	mutex_unlock(&tpg_instances_lock);

	kfree(opts);
}

static int tcm_register_callback(struct usb_function_instance *f)
{
	struct f_tcm_opts *opts = container_of(f, struct f_tcm_opts, func_inst);

	mutex_lock(&opts->dep_lock);
	opts->can_attach = true;
	mutex_unlock(&opts->dep_lock);

	return 0;
}

static void tcm_unregister_callback(struct usb_function_instance *f)
{
	struct f_tcm_opts *opts = container_of(f, struct f_tcm_opts, func_inst);

	mutex_lock(&opts->dep_lock);
	unregister_gadget_item(opts->
		func_inst.group.cg_item.ci_parent->ci_parent);
	opts->can_attach = false;
	mutex_unlock(&opts->dep_lock);
}

static int usbg_attach(struct usbg_tpg *tpg)
{
	struct usb_function_instance *f = tpg->fi;
	struct f_tcm_opts *opts = container_of(f, struct f_tcm_opts, func_inst);

	if (opts->tcm_register_callback)
		return opts->tcm_register_callback(f);

	return 0;
}

static void usbg_detach(struct usbg_tpg *tpg)
{
	struct usb_function_instance *f = tpg->fi;
	struct f_tcm_opts *opts = container_of(f, struct f_tcm_opts, func_inst);

	if (opts->tcm_unregister_callback)
		opts->tcm_unregister_callback(f);
}

static int tcm_set_name(struct usb_function_instance *f, const char *name)
{
	struct f_tcm_opts *opts = container_of(f, struct f_tcm_opts, func_inst);

	pr_debug("tcm: Activating %s\n", name);

	mutex_lock(&opts->dep_lock);
	opts->ready = true;
	mutex_unlock(&opts->dep_lock);

	return 0;
}

static struct usb_function_instance *tcm_alloc_inst(void)
{
	struct f_tcm_opts *opts;
	int i;


	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
	if (!opts)
		return ERR_PTR(-ENOMEM);

	mutex_lock(&tpg_instances_lock);
	for (i = 0; i < TPG_INSTANCES; ++i)
		if (!tpg_instances[i].func_inst)
			break;

	if (i == TPG_INSTANCES) {
		mutex_unlock(&tpg_instances_lock);
		kfree(opts);
		return ERR_PTR(-EBUSY);
	}
	tpg_instances[i].func_inst = &opts->func_inst;
	mutex_unlock(&tpg_instances_lock);

	mutex_init(&opts->dep_lock);
	opts->func_inst.set_inst_name = tcm_set_name;
	opts->func_inst.free_func_inst = tcm_free_inst;
	opts->tcm_register_callback = tcm_register_callback;
	opts->tcm_unregister_callback = tcm_unregister_callback;

	config_group_init_type_name(&opts->func_inst.group, "",
			&tcm_func_type);

	return &opts->func_inst;
}

static void tcm_free(struct usb_function *f)
{
	struct f_uas *tcm = to_f_uas(f);

	kfree(tcm);
}

static void tcm_unbind(struct usb_configuration *c, struct usb_function *f)
{
	usb_free_all_descriptors(f);
}

static struct usb_function *tcm_alloc(struct usb_function_instance *fi)
{
	struct f_uas *fu;
	unsigned i;

	mutex_lock(&tpg_instances_lock);
	for (i = 0; i < TPG_INSTANCES; ++i)
		if (tpg_instances[i].func_inst == fi)
			break;
	if (i == TPG_INSTANCES) {
		mutex_unlock(&tpg_instances_lock);
		return ERR_PTR(-ENODEV);
	}

	fu = kzalloc(sizeof(*fu), GFP_KERNEL);
	if (!fu) {
		mutex_unlock(&tpg_instances_lock);
		return ERR_PTR(-ENOMEM);
	}

	fu->function.name = "Target Function";
	fu->function.bind = tcm_bind;
	fu->function.unbind = tcm_unbind;
	fu->function.set_alt = tcm_set_alt;
	fu->function.get_alt = tcm_get_alt;
	fu->function.setup = tcm_setup;
	fu->function.disable = tcm_disable;
	fu->function.free_func = tcm_free;
	fu->tpg = tpg_instances[i].tpg;
	mutex_unlock(&tpg_instances_lock);

	return &fu->function;
}

DECLARE_USB_FUNCTION(tcm, tcm_alloc_inst, tcm_alloc);

static int __init tcm_init(void)
{
	int ret;

	ret = usb_function_register(&tcmusb_func);
	if (ret)
		return ret;

	ret = target_register_template(&usbg_ops);
	if (ret)
		usb_function_unregister(&tcmusb_func);

	return ret;
}
module_init(tcm_init);

static void __exit tcm_exit(void)
{
	target_unregister_template(&usbg_ops);
	usb_function_unregister(&tcmusb_func);
}
module_exit(tcm_exit);

MODULE_DESCRIPTION("Target based USB-Gadget");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sebastian Andrzej Siewior");