qemu/hw/usb/combined-packet.c

/*
 * QEMU USB packet combining code (for input pipelining)
 *
 * Copyright(c) 2012 Red Hat, Inc.
 *
 * Red Hat Authors:
 * Hans de Goede <hdegoede@redhat.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or(at your option) any later version.
 *
 * This library 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
 * Lesser 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 "qemu-common.h"
#include "hw/usb.h"
#include "iov.h"
#include "trace.h"

static void usb_combined_packet_add(USBCombinedPacket *combined, USBPacket *p)
{
    qemu_iovec_concat(&combined->iov, &p->iov, 0, p->iov.size);
    QTAILQ_INSERT_TAIL(&combined->packets, p, combined_entry);
    p->combined = combined;
}

static void usb_combined_packet_remove(USBCombinedPacket *combined,
                                       USBPacket *p)
{
    assert(p->combined == combined);
    p->combined = NULL;
    QTAILQ_REMOVE(&combined->packets, p, combined_entry);
}

/* Also handles completion of non combined packets for pipelined input eps */
void usb_combined_input_packet_complete(USBDevice *dev, USBPacket *p)
{
    USBCombinedPacket *combined = p->combined;
    USBEndpoint *ep = p->ep;
    USBPacket *next;
    enum { completing, complete, leftover };
    int result, state = completing;
    bool short_not_ok;

    if (combined == NULL) {
        usb_packet_complete_one(dev, p);
        goto leave;
    }

    assert(combined->first == p && p == QTAILQ_FIRST(&combined->packets));

    result = combined->first->result;
    short_not_ok = QTAILQ_LAST(&combined->packets, packets_head)->short_not_ok;

    QTAILQ_FOREACH_SAFE(p, &combined->packets, combined_entry, next) {
        if (state == completing) {
            /* Distribute data over uncombined packets */
            if (result >= p->iov.size) {
                p->result = p->iov.size;
            } else {
                /* Send short or error packet to complete the transfer */
                p->result = result;
                state = complete;
            }
            p->short_not_ok = short_not_ok;
            usb_combined_packet_remove(combined, p);
            usb_packet_complete_one(dev, p);
            result -= p->result;
        } else {
            /* Remove any leftover packets from the queue */
            state = leftover;
            p->result = USB_RET_REMOVE_FROM_QUEUE;
            dev->port->ops->complete(dev->port, p);
        }
    }
    /*
     * If we had leftover packets the hcd driver will have cancelled them
     * and usb_combined_packet_cancel has already freed combined!
     */
    if (state != leftover) {
        g_free(combined);
    }
leave:
    /* Check if there are packets in the queue waiting for our completion */
    usb_ep_combine_input_packets(ep);
}

/* May only be called for combined packets! */
void usb_combined_packet_cancel(USBDevice *dev, USBPacket *p)
{
    USBCombinedPacket *combined = p->combined;
    assert(combined != NULL);

    usb_combined_packet_remove(combined, p);
    if (p == combined->first) {
        usb_device_cancel_packet(dev, p);
    }
    if (QTAILQ_EMPTY(&combined->packets)) {
        g_free(combined);
    }
}

/*
 * Large input transfers can get split into multiple input packets, this
 * function recombines them, removing the short_not_ok checks which all but
 * the last packet of such splits transfers have, thereby allowing input
 * transfer pipelining (which we cannot do on short_not_ok transfers)
 */
void usb_ep_combine_input_packets(USBEndpoint *ep)
{
    USBPacket *p, *u, *next, *prev = NULL, *first = NULL;
    USBPort *port = ep->dev->port;
    int ret;

    assert(ep->pipeline);
    assert(ep->pid == USB_TOKEN_IN);

    QTAILQ_FOREACH_SAFE(p, &ep->queue, queue, next) {
        /* Empty the queue on a halt */
        if (ep->halted) {
            p->result = USB_RET_REMOVE_FROM_QUEUE;
            port->ops->complete(port, p);
            continue;
        }

        /* Skip packets already submitted to the device */
        if (p->state == USB_PACKET_ASYNC) {
            prev = p;
            continue;
        }
        usb_packet_check_state(p, USB_PACKET_QUEUED);

        /*
         * If the previous (combined) packet has the short_not_ok flag set
         * stop, as we must not submit packets to the device after a transfer
         * ending with short_not_ok packet.
         */
        if (prev && prev->short_not_ok) {
            break;
        }

        if (first) {
            if (first->combined == NULL) {
                USBCombinedPacket *combined = g_new0(USBCombinedPacket, 1);

                combined->first = first;
                QTAILQ_INIT(&combined->packets);
                qemu_iovec_init(&combined->iov, 2);
                usb_combined_packet_add(combined, first);
            }
            usb_combined_packet_add(first->combined, p);
        } else {
            first = p;
        }

        /* Is this packet the last one of a (combined) transfer? */
        if ((p->iov.size % ep->max_packet_size) != 0 || !p->short_not_ok ||
                next == NULL) {
            ret = usb_device_handle_data(ep->dev, first);
            assert(ret == USB_RET_ASYNC);
            if (first->combined) {
                QTAILQ_FOREACH(u, &first->combined->packets, combined_entry) {
                    usb_packet_set_state(u, USB_PACKET_ASYNC);
                }
            } else {
                usb_packet_set_state(first, USB_PACKET_ASYNC);
            }
            first = NULL;
            prev = p;
        }
    }
}