/*
 * Copyright (C) 2015 Jakub Kicinski <kubakici@wp.pl>
 *
 * 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.
 */

#include "mt7601u.h"
#include "dma.h"
#include "usb.h"
#include "trace.h"

static int mt7601u_submit_rx_buf(struct mt7601u_dev *dev,
                                 struct mt7601u_dma_buf_rx *e, gfp_t gfp);

static unsigned int ieee80211_get_hdrlen_from_buf(const u8 *data, unsigned len)
{
        const struct ieee80211_hdr *hdr = (const struct ieee80211_hdr *)data;
        unsigned int hdrlen;

        if (unlikely(len < 10))
                return 0;
        hdrlen = ieee80211_hdrlen(hdr->frame_control);
        if (unlikely(hdrlen > len))
                return 0;
        return hdrlen;
}

static struct sk_buff *
mt7601u_rx_skb_from_seg(struct mt7601u_dev *dev, struct mt7601u_rxwi *rxwi,
                        void *data, u32 seg_len, u32 truesize, struct page *p)
{
        struct sk_buff *skb;
        u32 true_len, hdr_len = 0, copy, frag;

        skb = alloc_skb(p ? 128 : seg_len, GFP_ATOMIC);
        if (!skb)
                return NULL;

        true_len = mt76_mac_process_rx(dev, skb, data, rxwi);
        if (!true_len || true_len > seg_len)
                goto bad_frame;

        hdr_len = ieee80211_get_hdrlen_from_buf(data, true_len);
        if (!hdr_len)
                goto bad_frame;

        if (rxwi->rxinfo & cpu_to_le32(MT_RXINFO_L2PAD)) {
                memcpy(skb_put(skb, hdr_len), data, hdr_len);

                data += hdr_len + 2;
                true_len -= hdr_len;
                hdr_len = 0;
        }

        /* If not doing paged RX allocated skb will always have enough space */
        copy = (true_len <= skb_tailroom(skb)) ? true_len : hdr_len + 8;
        frag = true_len - copy;

        memcpy(skb_put(skb, copy), data, copy);
        data += copy;

        if (frag) {
                skb_add_rx_frag(skb, 0, p, data - page_address(p),
                                frag, truesize);
                get_page(p);
        }

        return skb;

bad_frame:
        dev_err_ratelimited(dev->dev, "Error: incorrect frame len:%u hdr:%u\n",
                            true_len, hdr_len);
        dev_kfree_skb(skb);
        return NULL;
}

static void mt7601u_rx_process_seg(struct mt7601u_dev *dev, u8 *data,
                                   u32 seg_len, struct page *p)
{
        struct sk_buff *skb;
        struct mt7601u_rxwi *rxwi;
        u32 fce_info, truesize = seg_len;

        /* DMA_INFO field at the beginning of the segment contains only some of
         * the information, we need to read the FCE descriptor from the end.
         */
        fce_info = get_unaligned_le32(data + seg_len - MT_FCE_INFO_LEN);
        seg_len -= MT_FCE_INFO_LEN;

        data += MT_DMA_HDR_LEN;
        seg_len -= MT_DMA_HDR_LEN;

        rxwi = (struct mt7601u_rxwi *) data;
        data += sizeof(struct mt7601u_rxwi);
        seg_len -= sizeof(struct mt7601u_rxwi);

        if (unlikely(rxwi->zero[0] || rxwi->zero[1] || rxwi->zero[2]))
                dev_err_once(dev->dev, "Error: RXWI zero fields are set\n");
        if (unlikely(FIELD_GET(MT_RXD_INFO_TYPE, fce_info)))
                dev_err_once(dev->dev, "Error: RX path seen a non-pkt urb\n");

        trace_mt_rx(dev, rxwi, fce_info);

        skb = mt7601u_rx_skb_from_seg(dev, rxwi, data, seg_len, truesize, p);
        if (!skb)
                return;

        spin_lock(&dev->mac_lock);
        ieee80211_rx(dev->hw, skb);
        spin_unlock(&dev->mac_lock);
}

static u16 mt7601u_rx_next_seg_len(u8 *data, u32 data_len)
{
        u32 min_seg_len = MT_DMA_HDR_LEN + MT_RX_INFO_LEN +
                sizeof(struct mt7601u_rxwi) + MT_FCE_INFO_LEN;
        u16 dma_len = get_unaligned_le16(data);

        if (data_len < min_seg_len ||
            WARN_ON(!dma_len) ||
            WARN_ON(dma_len + MT_DMA_HDRS > data_len) ||
            WARN_ON(dma_len & 0x3))
                return 0;

        return MT_DMA_HDRS + dma_len;
}

static void
mt7601u_rx_process_entry(struct mt7601u_dev *dev, struct mt7601u_dma_buf_rx *e)
{
        u32 seg_len, data_len = e->urb->actual_length;
        u8 *data = page_address(e->p);
        struct page *new_p = NULL;
        int cnt = 0;

        if (!test_bit(MT7601U_STATE_INITIALIZED, &dev->state))
                return;

        /* Copy if there is very little data in the buffer. */
        if (data_len > 512)
                new_p = dev_alloc_pages(MT_RX_ORDER);

        while ((seg_len = mt7601u_rx_next_seg_len(data, data_len))) {
                mt7601u_rx_process_seg(dev, data, seg_len, new_p ? e->p : NULL);

                data_len -= seg_len;
                data += seg_len;
                cnt++;
        }

        if (cnt > 1)
                trace_mt_rx_dma_aggr(dev, cnt, !!new_p);

        if (new_p) {
                /* we have one extra ref from the allocator */
                __free_pages(e->p, MT_RX_ORDER);

                e->p = new_p;
        }
}

static struct mt7601u_dma_buf_rx *
mt7601u_rx_get_pending_entry(struct mt7601u_dev *dev)
{
        struct mt7601u_rx_queue *q = &dev->rx_q;
        struct mt7601u_dma_buf_rx *buf = NULL;
        unsigned long flags;

        spin_lock_irqsave(&dev->rx_lock, flags);

        if (!q->pending)
                goto out;

        buf = &q->e[q->start];
        q->pending--;
        q->start = (q->start + 1) % q->entries;
out:
        spin_unlock_irqrestore(&dev->rx_lock, flags);

        return buf;
}

static void mt7601u_complete_rx(struct urb *urb)
{
        struct mt7601u_dev *dev = urb->context;
        struct mt7601u_rx_queue *q = &dev->rx_q;
        unsigned long flags;

        spin_lock_irqsave(&dev->rx_lock, flags);

        if (mt7601u_urb_has_error(urb))
                dev_err(dev->dev, "Error: RX urb failed:%d\n", urb->status);
        if (WARN_ONCE(q->e[q->end].urb != urb, "RX urb mismatch"))
                goto out;

        q->end = (q->end + 1) % q->entries;
        q->pending++;
        tasklet_schedule(&dev->rx_tasklet);
out:
        spin_unlock_irqrestore(&dev->rx_lock, flags);
}

static void mt7601u_rx_tasklet(unsigned long data)
{
        struct mt7601u_dev *dev = (struct mt7601u_dev *) data;
        struct mt7601u_dma_buf_rx *e;

        while ((e = mt7601u_rx_get_pending_entry(dev))) {
                if (e->urb->status)
                        continue;

                mt7601u_rx_process_entry(dev, e);
                mt7601u_submit_rx_buf(dev, e, GFP_ATOMIC);
        }
}

static void mt7601u_complete_tx(struct urb *urb)
{
        struct mt7601u_tx_queue *q = urb->context;
        struct mt7601u_dev *dev = q->dev;
        struct sk_buff *skb;
        unsigned long flags;

        spin_lock_irqsave(&dev->tx_lock, flags);

        if (mt7601u_urb_has_error(urb))
                dev_err(dev->dev, "Error: TX urb failed:%d\n", urb->status);
        if (WARN_ONCE(q->e[q->start].urb != urb, "TX urb mismatch"))
                goto out;

        skb = q->e[q->start].skb;
        trace_mt_tx_dma_done(dev, skb);

        __skb_queue_tail(&dev->tx_skb_done, skb);
        tasklet_schedule(&dev->tx_tasklet);

        if (q->used == q->entries - q->entries / 8)
                ieee80211_wake_queue(dev->hw, skb_get_queue_mapping(skb));

        q->start = (q->start + 1) % q->entries;
        q->used--;
out:
        spin_unlock_irqrestore(&dev->tx_lock, flags);
}

static void mt7601u_tx_tasklet(unsigned long data)
{
        struct mt7601u_dev *dev = (struct mt7601u_dev *) data;
        struct sk_buff_head skbs;
        unsigned long flags;

        __skb_queue_head_init(&skbs);

        spin_lock_irqsave(&dev->tx_lock, flags);

        set_bit(MT7601U_STATE_MORE_STATS, &dev->state);
        if (!test_and_set_bit(MT7601U_STATE_READING_STATS, &dev->state))
                queue_delayed_work(dev->stat_wq, &dev->stat_work,
                                   msecs_to_jiffies(10));

        skb_queue_splice_init(&dev->tx_skb_done, &skbs);

        spin_unlock_irqrestore(&dev->tx_lock, flags);

        while (!skb_queue_empty(&skbs)) {
                struct sk_buff *skb = __skb_dequeue(&skbs);

                mt7601u_tx_status(dev, skb);
        }
}

static int mt7601u_dma_submit_tx(struct mt7601u_dev *dev,
                                 struct sk_buff *skb, u8 ep)
{
        struct usb_device *usb_dev = mt7601u_to_usb_dev(dev);
        unsigned snd_pipe = usb_sndbulkpipe(usb_dev, dev->out_eps[ep]);
        struct mt7601u_dma_buf_tx *e;
        struct mt7601u_tx_queue *q = &dev->tx_q[ep];
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&dev->tx_lock, flags);

        if (WARN_ON(q->entries <= q->used)) {
                ret = -ENOSPC;
                goto out;
        }

        e = &q->e[q->end];
        e->skb = skb;
        usb_fill_bulk_urb(e->urb, usb_dev, snd_pipe, skb->data, skb->len,
                          mt7601u_complete_tx, q);
        ret = usb_submit_urb(e->urb, GFP_ATOMIC);
        if (ret) {
                /* Special-handle ENODEV from TX urb submission because it will
                 * often be the first ENODEV we see after device is removed.
                 */
                if (ret == -ENODEV)
                        set_bit(MT7601U_STATE_REMOVED, &dev->state);
                else
                        dev_err(dev->dev, "Error: TX urb submit failed:%d\n",
                                ret);
                goto out;
        }

        q->end = (q->end + 1) % q->entries;
        q->used++;

        if (q->used >= q->entries)
                ieee80211_stop_queue(dev->hw, skb_get_queue_mapping(skb));
out:
        spin_unlock_irqrestore(&dev->tx_lock, flags);

        return ret;
}

/* Map hardware Q to USB endpoint number */
static u8 q2ep(u8 qid)
{
        /* TODO: take management packets to queue 5 */
        return qid + 1;
}

/* Map USB endpoint number to Q id in the DMA engine */
static enum mt76_qsel ep2dmaq(u8 ep)
{
        if (ep == 5)
                return MT_QSEL_MGMT;
        return MT_QSEL_EDCA;
}

int mt7601u_dma_enqueue_tx(struct mt7601u_dev *dev, struct sk_buff *skb,
                           struct mt76_wcid *wcid, int hw_q)
{
        u8 ep = q2ep(hw_q);
        u32 dma_flags;
        int ret;

        dma_flags = MT_TXD_PKT_INFO_80211;
        if (wcid->hw_key_idx == 0xff)
                dma_flags |= MT_TXD_PKT_INFO_WIV;

        ret = mt7601u_dma_skb_wrap_pkt(skb, ep2dmaq(ep), dma_flags);
        if (ret)
                return ret;

        ret = mt7601u_dma_submit_tx(dev, skb, ep);
        if (ret) {
                ieee80211_free_txskb(dev->hw, skb);
                return ret;
        }

        return 0;
}

static void mt7601u_kill_rx(struct mt7601u_dev *dev)
{
        int i;
        unsigned long flags;

        spin_lock_irqsave(&dev->rx_lock, flags);

        for (i = 0; i < dev->rx_q.entries; i++) {
                int next = dev->rx_q.end;

                spin_unlock_irqrestore(&dev->rx_lock, flags);
                usb_poison_urb(dev->rx_q.e[next].urb);
                spin_lock_irqsave(&dev->rx_lock, flags);
        }

        spin_unlock_irqrestore(&dev->rx_lock, flags);
}

static int mt7601u_submit_rx_buf(struct mt7601u_dev *dev,
                                 struct mt7601u_dma_buf_rx *e, gfp_t gfp)
{
        struct usb_device *usb_dev = mt7601u_to_usb_dev(dev);
        u8 *buf = page_address(e->p);
        unsigned pipe;
        int ret;

        pipe = usb_rcvbulkpipe(usb_dev, dev->in_eps[MT_EP_IN_PKT_RX]);

        usb_fill_bulk_urb(e->urb, usb_dev, pipe, buf, MT_RX_URB_SIZE,
                          mt7601u_complete_rx, dev);

        trace_mt_submit_urb(dev, e->urb);
        ret = usb_submit_urb(e->urb, gfp);
        if (ret)
                dev_err(dev->dev, "Error: submit RX URB failed:%d\n", ret);

        return ret;
}

static int mt7601u_submit_rx(struct mt7601u_dev *dev)
{
        int i, ret;

        for (i = 0; i < dev->rx_q.entries; i++) {
                ret = mt7601u_submit_rx_buf(dev, &dev->rx_q.e[i], GFP_KERNEL);
                if (ret)
                        return ret;
        }

        return 0;
}

static void mt7601u_free_rx(struct mt7601u_dev *dev)
{
        int i;

        for (i = 0; i < dev->rx_q.entries; i++) {
                __free_pages(dev->rx_q.e[i].p, MT_RX_ORDER);
                usb_free_urb(dev->rx_q.e[i].urb);
        }
}

static int mt7601u_alloc_rx(struct mt7601u_dev *dev)
{
        int i;

        memset(&dev->rx_q, 0, sizeof(dev->rx_q));
        dev->rx_q.dev = dev;
        dev->rx_q.entries = N_RX_ENTRIES;

        for (i = 0; i < N_RX_ENTRIES; i++) {
                dev->rx_q.e[i].urb = usb_alloc_urb(0, GFP_KERNEL);
                dev->rx_q.e[i].p = dev_alloc_pages(MT_RX_ORDER);

                if (!dev->rx_q.e[i].urb || !dev->rx_q.e[i].p)
                        return -ENOMEM;
        }

        return 0;
}

static void mt7601u_free_tx_queue(struct mt7601u_tx_queue *q)
{
        int i;

        WARN_ON(q->used);

        for (i = 0; i < q->entries; i++)  {
                usb_poison_urb(q->e[i].urb);
                usb_free_urb(q->e[i].urb);
        }
}

static void mt7601u_free_tx(struct mt7601u_dev *dev)
{
        int i;

        for (i = 0; i < __MT_EP_OUT_MAX; i++)
                mt7601u_free_tx_queue(&dev->tx_q[i]);
}

static int mt7601u_alloc_tx_queue(struct mt7601u_dev *dev,
                                  struct mt7601u_tx_queue *q)
{
        int i;

        q->dev = dev;
        q->entries = N_TX_ENTRIES;

        for (i = 0; i < N_TX_ENTRIES; i++) {
                q->e[i].urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!q->e[i].urb)
                        return -ENOMEM;
        }

        return 0;
}

static int mt7601u_alloc_tx(struct mt7601u_dev *dev)
{
        int i;

        dev->tx_q = devm_kcalloc(dev->dev, __MT_EP_OUT_MAX,
                                 sizeof(*dev->tx_q), GFP_KERNEL);

        for (i = 0; i < __MT_EP_OUT_MAX; i++)
                if (mt7601u_alloc_tx_queue(dev, &dev->tx_q[i]))
                        return -ENOMEM;

        return 0;
}

int mt7601u_dma_init(struct mt7601u_dev *dev)
{
        int ret = -ENOMEM;

        tasklet_init(&dev->tx_tasklet, mt7601u_tx_tasklet, (unsigned long) dev);
        tasklet_init(&dev->rx_tasklet, mt7601u_rx_tasklet, (unsigned long) dev);

        ret = mt7601u_alloc_tx(dev);
        if (ret)
                goto err;
        ret = mt7601u_alloc_rx(dev);
        if (ret)
                goto err;

        ret = mt7601u_submit_rx(dev);
        if (ret)
                goto err;

        return 0;
err:
        mt7601u_dma_cleanup(dev);
        return ret;
}

void mt7601u_dma_cleanup(struct mt7601u_dev *dev)
{
        mt7601u_kill_rx(dev);

        tasklet_kill(&dev->rx_tasklet);

        mt7601u_free_rx(dev);
        mt7601u_free_tx(dev);

        tasklet_kill(&dev->tx_tasklet);
}