add mt7601u driver

Add support for the simplest of MediaTek Wi-Fi devices - MT7601U.
It is a single stream bgn chip with no bells or whistles.
This driver is partially based on Felix's mt76 but IMHO it doesn't
make sense to merge the two right now because MT7601U is a design
somewhere between old Ralink devices and new Mediatek chips.  There
wouldn't be all that much code sharing with the devices mt76 supports.
Situation may obviously change when someone decides to extend m76 with
support for the more recent USB dongles.

The driver supports only station mode.  I'm hoping to add AP support
when time allows.

This driver sat on GitHub for quite a while and got some testing there:
http://github.com/kuba-moo/mt7601u

Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

1 files changed, 533 insertions, 0 deletions

diff --git a/drivers/net/wireless/mediatek/mt7601u/dma.c b/drivers/net/wireless/mediatek/mt7601u/dma.c
new file mode 100644
index 000000000000..9c9e1288644b
--- /dev/null
+++ b/drivers/net/wireless/mediatek/mt7601u/dma.c
@@ -0,0 +1,533 @@
+/*
+ * 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,
+			u8 *data, u32 seg_len)
+{
+	struct sk_buff *skb;
+	u32 true_len;
+
+	if (rxwi->rxinfo & cpu_to_le32(MT_RXINFO_L2PAD))
+		seg_len -= 2;
+
+	skb = alloc_skb(seg_len, GFP_ATOMIC);
+	if (!skb)
+		return NULL;
+
+	if (rxwi->rxinfo & cpu_to_le32(MT_RXINFO_L2PAD)) {
+		int hdr_len = ieee80211_get_hdrlen_from_buf(data, seg_len);
+
+		memcpy(skb_put(skb, hdr_len), data, hdr_len);
+		data += hdr_len + 2;
+		seg_len -= hdr_len;
+	}
+
+	memcpy(skb_put(skb, seg_len), data, seg_len);
+
+	true_len = mt76_mac_process_rx(dev, skb, skb->data, rxwi);
+	skb_trim(skb, true_len);
+
+	return skb;
+}
+
+static struct sk_buff *
+mt7601u_rx_skb_from_seg_paged(struct mt7601u_dev *dev,
+			      struct mt7601u_rxwi *rxwi, void *data,
+			      u32 seg_len, u32 truesize, struct page *p)
+{
+	unsigned int hdr_len = ieee80211_get_hdrlen_from_buf(data, seg_len);
+	unsigned int true_len, copy, frag;
+	struct sk_buff *skb;
+
+	skb = alloc_skb(128, GFP_ATOMIC);
+	if (!skb)
+		return NULL;
+
+	true_len = mt76_mac_process_rx(dev, skb, data, rxwi);
+
+	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;
+	}
+
+	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;
+}
+
+static void mt7601u_rx_process_seg(struct mt7601u_dev *dev, u8 *data,
+				   u32 seg_len, struct page *p, bool paged)
+{
+	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(MT76_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);
+
+	if (paged)
+		skb = mt7601u_rx_skb_from_seg_paged(dev, rxwi, data, seg_len,
+						    truesize, p);
+	else
+		skb = mt7601u_rx_skb_from_seg(dev, rxwi, data, seg_len);
+	if (!skb)
+		return;
+
+	ieee80211_rx_ni(dev->hw, skb);
+}
+
+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;
+	bool paged = true;
+	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) {
+		paged = false;
+	} else {
+		new_p = dev_alloc_pages(MT_RX_ORDER);
+		if (!new_p)
+			paged = false;
+	}
+
+	while ((seg_len = mt7601u_rx_next_seg_len(data, data_len))) {
+		mt7601u_rx_process_seg(dev, data, seg_len, e->p, paged);
+
+		data_len -= seg_len;
+		data += seg_len;
+		cnt++;
+	}
+
+	if (cnt > 1)
+		trace_mt_rx_dma_aggr(dev, cnt, paged);
+
+	if (paged) {
+		/* 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);
+
+	mt7601u_tx_status(dev, skb);
+
+	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--;
+
+	if (urb->status)
+		goto out;
+
+	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));
+out:
+	spin_unlock_irqrestore(&dev->tx_lock, flags);
+}
+
+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->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);
+}