/*
 * Wireless Host Controller (WHC) asynchronous schedule management.
 *
 * Copyright (C) 2007 Cambridge Silicon Radio Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * 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 <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/dma-mapping.h>
#include <linux/uwb/umc.h>
#include <linux/usb.h>

#include "../../wusbcore/wusbhc.h"

#include "whcd.h"

static void qset_get_next_prev(struct whc *whc, struct whc_qset *qset,
                               struct whc_qset **next, struct whc_qset **prev)
{
        struct list_head *n, *p;

        BUG_ON(list_empty(&whc->async_list));

        n = qset->list_node.next;
        if (n == &whc->async_list)
                n = n->next;
        p = qset->list_node.prev;
        if (p == &whc->async_list)
                p = p->prev;

        *next = container_of(n, struct whc_qset, list_node);
        *prev = container_of(p, struct whc_qset, list_node);

}

static void asl_qset_insert_begin(struct whc *whc, struct whc_qset *qset)
{
        list_move(&qset->list_node, &whc->async_list);
        qset->in_sw_list = true;
}

static void asl_qset_insert(struct whc *whc, struct whc_qset *qset)
{
        struct whc_qset *next, *prev;

        qset_clear(whc, qset);

        /* Link into ASL. */
        qset_get_next_prev(whc, qset, &next, &prev);
        whc_qset_set_link_ptr(&qset->qh.link, next->qset_dma);
        whc_qset_set_link_ptr(&prev->qh.link, qset->qset_dma);
        qset->in_hw_list = true;
}

static void asl_qset_remove(struct whc *whc, struct whc_qset *qset)
{
        struct whc_qset *prev, *next;

        qset_get_next_prev(whc, qset, &next, &prev);

        list_move(&qset->list_node, &whc->async_removed_list);
        qset->in_sw_list = false;

        /*
         * No more qsets in the ASL?  The caller must stop the ASL as
         * it's no longer valid.
         */
        if (list_empty(&whc->async_list))
                return;

        /* Remove from ASL. */
        whc_qset_set_link_ptr(&prev->qh.link, next->qset_dma);
        qset->in_hw_list = false;
}

/**
 * process_qset - process any recently inactivated or halted qTDs in a
 * qset.
 *
 * After inactive qTDs are removed, new qTDs can be added if the
 * urb queue still contains URBs.
 *
 * Returns any additional WUSBCMD bits for the ASL sync command (i.e.,
 * WUSBCMD_ASYNC_QSET_RM if a halted qset was removed).
 */
static uint32_t process_qset(struct whc *whc, struct whc_qset *qset)
{
        enum whc_update update = 0;
        uint32_t status = 0;

        while (qset->ntds) {
                struct whc_qtd *td;
                int t;

                t = qset->td_start;
                td = &qset->qtd[qset->td_start];
                status = le32_to_cpu(td->status);

                /*
                 * Nothing to do with a still active qTD.
                 */
                if (status & QTD_STS_ACTIVE)
                        break;

                if (status & QTD_STS_HALTED) {
                        /* Ug, an error. */
                        process_halted_qtd(whc, qset, td);
                        /* A halted qTD always triggers an update
                           because the qset was either removed or
                           reactivated. */
                        update |= WHC_UPDATE_UPDATED;
                        goto done;
                }

                /* Mmm, a completed qTD. */
                process_inactive_qtd(whc, qset, td);
        }

        if (!qset->remove)
                update |= qset_add_qtds(whc, qset);

done:
        /*
         * Remove this qset from the ASL if requested, but only if has
         * no qTDs.
         */
        if (qset->remove && qset->ntds == 0) {
                asl_qset_remove(whc, qset);
                update |= WHC_UPDATE_REMOVED;
        }
        return update;
}

void asl_start(struct whc *whc)
{
        struct whc_qset *qset;

        qset = list_first_entry(&whc->async_list, struct whc_qset, list_node);

        le_writeq(qset->qset_dma | QH_LINK_NTDS(8), whc->base + WUSBASYNCLISTADDR);

        whc_write_wusbcmd(whc, WUSBCMD_ASYNC_EN, WUSBCMD_ASYNC_EN);
        whci_wait_for(&whc->umc->dev, whc->base + WUSBSTS,
                      WUSBSTS_ASYNC_SCHED, WUSBSTS_ASYNC_SCHED,
                      1000, "start ASL");
}

void asl_stop(struct whc *whc)
{
        whc_write_wusbcmd(whc, WUSBCMD_ASYNC_EN, 0);
        whci_wait_for(&whc->umc->dev, whc->base + WUSBSTS,
                      WUSBSTS_ASYNC_SCHED, 0,
                      1000, "stop ASL");
}

/**
 * asl_update - request an ASL update and wait for the hardware to be synced
 * @whc: the WHCI HC
 * @wusbcmd: WUSBCMD value to start the update.
 *
 * If the WUSB HC is inactive (i.e., the ASL is stopped) then the
 * update must be skipped as the hardware may not respond to update
 * requests.
 */
void asl_update(struct whc *whc, uint32_t wusbcmd)
{
        struct wusbhc *wusbhc = &whc->wusbhc;
        long t;

        mutex_lock(&wusbhc->mutex);
        if (wusbhc->active) {
                whc_write_wusbcmd(whc, wusbcmd, wusbcmd);
                t = wait_event_timeout(
                        whc->async_list_wq,
                        (le_readl(whc->base + WUSBCMD) & WUSBCMD_ASYNC_UPDATED) == 0,
                        msecs_to_jiffies(1000));
                if (t == 0)
                        whc_hw_error(whc, "ASL update timeout");
        }
        mutex_unlock(&wusbhc->mutex);
}

/**
 * scan_async_work - scan the ASL for qsets to process.
 *
 * Process each qset in the ASL in turn and then signal the WHC that
 * the ASL has been updated.
 *
 * Then start, stop or update the asynchronous schedule as required.
 */
void scan_async_work(struct work_struct *work)
{
        struct whc *whc = container_of(work, struct whc, async_work);
        struct whc_qset *qset, *t;
        enum whc_update update = 0;

        spin_lock_irq(&whc->lock);

        /*
         * Transerve the software list backwards so new qsets can be
         * safely inserted into the ASL without making it non-circular.
         */
        list_for_each_entry_safe_reverse(qset, t, &whc->async_list, list_node) {
                if (!qset->in_hw_list) {
                        asl_qset_insert(whc, qset);
                        update |= WHC_UPDATE_ADDED;
                }

                update |= process_qset(whc, qset);
        }

        spin_unlock_irq(&whc->lock);

        if (update) {
                uint32_t wusbcmd = WUSBCMD_ASYNC_UPDATED | WUSBCMD_ASYNC_SYNCED_DB;
                if (update & WHC_UPDATE_REMOVED)
                        wusbcmd |= WUSBCMD_ASYNC_QSET_RM;
                asl_update(whc, wusbcmd);
        }

        /*
         * Now that the ASL is updated, complete the removal of any
         * removed qsets.
         *
         * If the qset was to be reset, do so and reinsert it into the
         * ASL if it has pending transfers.
         */
        spin_lock_irq(&whc->lock);

        list_for_each_entry_safe(qset, t, &whc->async_removed_list, list_node) {
                qset_remove_complete(whc, qset);
                if (qset->reset) {
                        qset_reset(whc, qset);
                        if (!list_empty(&qset->stds)) {
                                asl_qset_insert_begin(whc, qset);
                                queue_work(whc->workqueue, &whc->async_work);
                        }
                }
        }

        spin_unlock_irq(&whc->lock);
}

/**
 * asl_urb_enqueue - queue an URB onto the asynchronous list (ASL).
 * @whc: the WHCI host controller
 * @urb: the URB to enqueue
 * @mem_flags: flags for any memory allocations
 *
 * The qset for the endpoint is obtained and the urb queued on to it.
 *
 * Work is scheduled to update the hardware's view of the ASL.
 */
int asl_urb_enqueue(struct whc *whc, struct urb *urb, gfp_t mem_flags)
{
        struct whc_qset *qset;
        int err;
        unsigned long flags;

        spin_lock_irqsave(&whc->lock, flags);

        err = usb_hcd_link_urb_to_ep(&whc->wusbhc.usb_hcd, urb);
        if (err < 0) {
                spin_unlock_irqrestore(&whc->lock, flags);
                return err;
        }

        qset = get_qset(whc, urb, GFP_ATOMIC);
        if (qset == NULL)
                err = -ENOMEM;
        else
                err = qset_add_urb(whc, qset, urb, GFP_ATOMIC);
        if (!err) {
                if (!qset->in_sw_list && !qset->remove)
                        asl_qset_insert_begin(whc, qset);
        } else
                usb_hcd_unlink_urb_from_ep(&whc->wusbhc.usb_hcd, urb);

        spin_unlock_irqrestore(&whc->lock, flags);

        if (!err)
                queue_work(whc->workqueue, &whc->async_work);

        return err;
}

/**
 * asl_urb_dequeue - remove an URB (qset) from the async list.
 * @whc: the WHCI host controller
 * @urb: the URB to dequeue
 * @status: the current status of the URB
 *
 * URBs that do yet have qTDs can simply be removed from the software
 * queue, otherwise the qset must be removed from the ASL so the qTDs
 * can be removed.
 */
int asl_urb_dequeue(struct whc *whc, struct urb *urb, int status)
{
        struct whc_urb *wurb = urb->hcpriv;
        struct whc_qset *qset = wurb->qset;
        struct whc_std *std, *t;
        bool has_qtd = false;
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&whc->lock, flags);

        ret = usb_hcd_check_unlink_urb(&whc->wusbhc.usb_hcd, urb, status);
        if (ret < 0)
                goto out;

        list_for_each_entry_safe(std, t, &qset->stds, list_node) {
                if (std->urb == urb) {
                        if (std->qtd)
                                has_qtd = true;
                        qset_free_std(whc, std);
                } else
                        std->qtd = NULL; /* so this std is re-added when the qset is */
        }

        if (has_qtd) {
                asl_qset_remove(whc, qset);
                wurb->status = status;
                wurb->is_async = true;
                queue_work(whc->workqueue, &wurb->dequeue_work);
        } else
                qset_remove_urb(whc, qset, urb, status);
out:
        spin_unlock_irqrestore(&whc->lock, flags);

        return ret;
}

/**
 * asl_qset_delete - delete a qset from the ASL
 */
void asl_qset_delete(struct whc *whc, struct whc_qset *qset)
{
        qset->remove = 1;
        queue_work(whc->workqueue, &whc->async_work);
        qset_delete(whc, qset);
}

/**
 * asl_init - initialize the asynchronous schedule list
 *
 * A dummy qset with no qTDs is added to the ASL to simplify removing
 * qsets (no need to stop the ASL when the last qset is removed).
 */
int asl_init(struct whc *whc)
{
        struct whc_qset *qset;

        qset = qset_alloc(whc, GFP_KERNEL);
        if (qset == NULL)
                return -ENOMEM;

        asl_qset_insert_begin(whc, qset);
        asl_qset_insert(whc, qset);

        return 0;
}

/**
 * asl_clean_up - free ASL resources
 *
 * The ASL is stopped and empty except for the dummy qset.
 */
void asl_clean_up(struct whc *whc)
{
        struct whc_qset *qset;

        if (!list_empty(&whc->async_list)) {
                qset = list_first_entry(&whc->async_list, struct whc_qset, list_node);
                list_del(&qset->list_node);
                qset_free(whc, qset);
        }
}