/*
 * Copyright (C) 2015 Karol Kosik <karo9@interia.eu>
 * Copyright (C) 2015-2016 Samsung Electronics
 *               Igor Kotrasinski <i.kotrasinsk@samsung.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <net/sock.h>
#include <linux/list.h>
#include <linux/kthread.h>

#include "usbip_common.h"
#include "vudc.h"

static inline void setup_base_pdu(struct usbip_header_basic *base,
				  __u32 command, __u32 seqnum)
{
	base->command	= command;
	base->seqnum	= seqnum;
	base->devid	= 0;
	base->ep	= 0;
	base->direction = 0;
}

static void setup_ret_submit_pdu(struct usbip_header *rpdu, struct urbp *urb_p)
{
	setup_base_pdu(&rpdu->base, USBIP_RET_SUBMIT, urb_p->seqnum);
	usbip_pack_pdu(rpdu, urb_p->urb, USBIP_RET_SUBMIT, 1);
}

static void setup_ret_unlink_pdu(struct usbip_header *rpdu,
				 struct v_unlink *unlink)
{
	setup_base_pdu(&rpdu->base, USBIP_RET_UNLINK, unlink->seqnum);
	rpdu->u.ret_unlink.status = unlink->status;
}

static int v_send_ret_unlink(struct vudc *udc, struct v_unlink *unlink)
{
	struct msghdr msg;
	struct kvec iov[1];
	size_t txsize;

	int ret;
	struct usbip_header pdu_header;

	txsize = 0;
	memset(&pdu_header, 0, sizeof(pdu_header));
	memset(&msg, 0, sizeof(msg));
	memset(&iov, 0, sizeof(iov));

	/* 1. setup usbip_header */
	setup_ret_unlink_pdu(&pdu_header, unlink);
	usbip_header_correct_endian(&pdu_header, 1);

	iov[0].iov_base = &pdu_header;
	iov[0].iov_len  = sizeof(pdu_header);
	txsize += sizeof(pdu_header);

	ret = kernel_sendmsg(udc->ud.tcp_socket, &msg, iov,
			     1, txsize);
	if (ret != txsize) {
		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
		if (ret >= 0)
			return -EPIPE;
		return ret;
	}
	kfree(unlink);

	return txsize;
}

static int v_send_ret_submit(struct vudc *udc, struct urbp *urb_p)
{
	struct urb *urb = urb_p->urb;
	struct usbip_header pdu_header;
	struct usbip_iso_packet_descriptor *iso_buffer = NULL;
	struct kvec *iov = NULL;
	int iovnum = 0;
	int ret = 0;
	size_t txsize;
	struct msghdr msg;

	txsize = 0;
	memset(&pdu_header, 0, sizeof(pdu_header));
	memset(&msg, 0, sizeof(msg));

	if (urb_p->type == USB_ENDPOINT_XFER_ISOC)
		iovnum = 2 + urb->number_of_packets;
	else
		iovnum = 2;

	iov = kcalloc(iovnum, sizeof(*iov), GFP_KERNEL);
	if (!iov) {
		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);
		ret = -ENOMEM;
		goto out;
	}
	iovnum = 0;

	/* 1. setup usbip_header */
	setup_ret_submit_pdu(&pdu_header, urb_p);
	usbip_dbg_stub_tx("setup txdata seqnum: %d urb: %p\n",
			  pdu_header.base.seqnum, urb);
	usbip_header_correct_endian(&pdu_header, 1);

	iov[iovnum].iov_base = &pdu_header;
	iov[iovnum].iov_len  = sizeof(pdu_header);
	iovnum++;
	txsize += sizeof(pdu_header);

	/* 2. setup transfer buffer */
	if (urb_p->type != USB_ENDPOINT_XFER_ISOC &&
	    usb_pipein(urb->pipe) && urb->actual_length > 0) {
		iov[iovnum].iov_base = urb->transfer_buffer;
		iov[iovnum].iov_len  = urb->actual_length;
		iovnum++;
		txsize += urb->actual_length;
	} else if (urb_p->type == USB_ENDPOINT_XFER_ISOC &&
		usb_pipein(urb->pipe)) {
		/* FIXME - copypasted from stub_tx, refactor */
		int i;

		for (i = 0; i < urb->number_of_packets; i++) {
			iov[iovnum].iov_base = urb->transfer_buffer +
				urb->iso_frame_desc[i].offset;
			iov[iovnum].iov_len =
				urb->iso_frame_desc[i].actual_length;
			iovnum++;
			txsize += urb->iso_frame_desc[i].actual_length;
		}

		if (txsize != sizeof(pdu_header) + urb->actual_length) {
			usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
			ret = -EPIPE;
			goto out;
		}
	}
	/* else - no buffer to send */

	/* 3. setup iso_packet_descriptor */
	if (urb_p->type == USB_ENDPOINT_XFER_ISOC) {
		ssize_t len = 0;

		iso_buffer = usbip_alloc_iso_desc_pdu(urb, &len);
		if (!iso_buffer) {
			usbip_event_add(&udc->ud,
					VUDC_EVENT_ERROR_MALLOC);
			ret = -ENOMEM;
			goto out;
		}

		iov[iovnum].iov_base = iso_buffer;
		iov[iovnum].iov_len  = len;
		txsize += len;
		iovnum++;
	}

	ret = kernel_sendmsg(udc->ud.tcp_socket, &msg,
						iov,  iovnum, txsize);
	if (ret != txsize) {
		usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_TCP);
		if (ret >= 0)
			ret = -EPIPE;
		goto out;
	}

out:
	kfree(iov);
	kfree(iso_buffer);
	free_urbp_and_urb(urb_p);
	if (ret < 0)
		return ret;
	return txsize;
}

static int v_send_ret(struct vudc *udc)
{
	unsigned long flags;
	struct tx_item *txi;
	size_t total_size = 0;
	int ret = 0;

	spin_lock_irqsave(&udc->lock_tx, flags);
	while (!list_empty(&udc->tx_queue)) {
		txi = list_first_entry(&udc->tx_queue, struct tx_item,
				       tx_entry);
		list_del(&txi->tx_entry);
		spin_unlock_irqrestore(&udc->lock_tx, flags);

		switch (txi->type) {
		case TX_SUBMIT:
			ret = v_send_ret_submit(udc, txi->s);
			break;
		case TX_UNLINK:
			ret = v_send_ret_unlink(udc, txi->u);
			break;
		}
		kfree(txi);

		if (ret < 0)
			return ret;

		total_size += ret;

		spin_lock_irqsave(&udc->lock_tx, flags);
	}

	spin_unlock_irqrestore(&udc->lock_tx, flags);
	return total_size;
}


int v_tx_loop(void *data)
{
	struct usbip_device *ud = (struct usbip_device *) data;
	struct vudc *udc = container_of(ud, struct vudc, ud);
	int ret;

	while (!kthread_should_stop()) {
		if (usbip_event_happened(&udc->ud))
			break;
		ret = v_send_ret(udc);
		if (ret < 0) {
			pr_warn("v_tx exit with error %d", ret);
			break;
		}
		wait_event_interruptible(udc->tx_waitq,
					 (!list_empty(&udc->tx_queue) ||
					 kthread_should_stop()));
	}

	return 0;
}

/* called with spinlocks held */
void v_enqueue_ret_unlink(struct vudc *udc, __u32 seqnum, __u32 status)
{
	struct tx_item *txi;
	struct v_unlink *unlink;

	txi = kzalloc(sizeof(*txi), GFP_ATOMIC);
	if (!txi) {
		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
		return;
	}
	unlink = kzalloc(sizeof(*unlink), GFP_ATOMIC);
	if (!unlink) {
		kfree(txi);
		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
		return;
	}

	unlink->seqnum = seqnum;
	unlink->status = status;
	txi->type = TX_UNLINK;
	txi->u = unlink;

	list_add_tail(&txi->tx_entry, &udc->tx_queue);
}

/* called with spinlocks held */
void v_enqueue_ret_submit(struct vudc *udc, struct urbp *urb_p)
{
	struct tx_item *txi;

	txi = kzalloc(sizeof(*txi), GFP_ATOMIC);
	if (!txi) {
		usbip_event_add(&udc->ud, VDEV_EVENT_ERROR_MALLOC);
		return;
	}

	txi->type = TX_SUBMIT;
	txi->s = urb_p;

	list_add_tail(&txi->tx_entry, &udc->tx_queue);
}