carl9170usb: 802.11 rx/tx processing and usb backend

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@@ -0,0 +1,910 @@
+/*
+ * Atheros CARL9170 driver
+ *
+ * 802.11 & command trap routines
+ *
+ * Copyright 2008, Johannes Berg <[email protected]>
+ * Copyright 2009, 2010, Christian Lamparter <[email protected]>
+ *
+ * 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; see the file COPYING.  If not, see
+ * http://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *    Copyright (c) 2007-2008 Atheros Communications, Inc.
+ *
+ *    Permission to use, copy, modify, and/or distribute this software for any
+ *    purpose with or without fee is hereby granted, provided that the above
+ *    copyright notice and this permission notice appear in all copies.
+ *
+ *    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/etherdevice.h>
+#include <linux/crc32.h>
+#include <net/mac80211.h>
+#include "carl9170.h"
+#include "hw.h"
+#include "cmd.h"
+
+static void carl9170_dbg_message(struct ar9170 *ar, const char *buf, u32 len)
+{
+	bool restart = false;
+	enum carl9170_restart_reasons reason = CARL9170_RR_NO_REASON;
+
+	if (len > 3) {
+		if (memcmp(buf, CARL9170_ERR_MAGIC, 3) == 0) {
+			ar->fw_err_counter++;
+			if (ar->fw_err_counter > 3) {
+				restart = true;
+				reason = CARL9170_RR_TOO_MANY_FIRMWARE_ERRORS;
+			}
+		}
+
+		if (memcmp(buf, CARL9170_BUG_MAGIC, 3) == 0) {
+			ar->fw_bug_counter++;
+			restart = true;
+			reason = CARL9170_RR_FATAL_FIRMWARE_ERROR;
+		}
+	}
+
+	wiphy_info(ar->hw->wiphy, "FW: %.*s\n", len, buf);
+
+	if (restart)
+		carl9170_restart(ar, reason);
+}
+
+static void carl9170_handle_ps(struct ar9170 *ar, struct carl9170_rsp *rsp)
+{
+	u32 ps;
+	bool new_ps;
+
+	ps = le32_to_cpu(rsp->psm.state);
+
+	new_ps = (ps & CARL9170_PSM_COUNTER) != CARL9170_PSM_WAKE;
+	if (ar->ps_state != new_ps) {
+		if (!new_ps) {
+			ar->ps_sleep_ms = jiffies_to_msecs(jiffies -
+				ar->ps_last_action);
+		}
+
+		ar->ps_last_action = jiffies;
+
+		ar->ps_state = new_ps;
+	}
+}
+
+static int carl9170_check_sequence(struct ar9170 *ar, unsigned int seq)
+{
+	if (ar->cmd_seq < -1)
+		return 0;
+
+	/*
+	 * Initialize Counter
+	 */
+	if (ar->cmd_seq < 0)
+		ar->cmd_seq = seq;
+
+	/*
+	 * The sequence is strictly monotonic increasing and it never skips!
+	 *
+	 * Therefore we can safely assume that whenever we received an
+	 * unexpected sequence we have lost some valuable data.
+	 */
+	if (seq != ar->cmd_seq) {
+		int count;
+
+		count = (seq - ar->cmd_seq) % ar->fw_cmd_bufs;
+
+		wiphy_err(ar->hw->wiphy, "lost %d command responses/traps! "
+			  "w:%d g:%d\n", count, ar->cmd_seq, seq);
+
+		carl9170_restart(ar, CARL9170_RR_LOST_RSP);
+		return -EIO;
+	}
+
+	ar->cmd_seq = (ar->cmd_seq + 1) % ar->fw_cmd_bufs;
+	return 0;
+}
+
+static void carl9170_cmd_callback(struct ar9170 *ar, u32 len, void *buffer)
+{
+	/*
+	 * Some commands may have a variable response length
+	 * and we cannot predict the correct length in advance.
+	 * So we only check if we provided enough space for the data.
+	 */
+	if (unlikely(ar->readlen != (len - 4))) {
+		dev_warn(&ar->udev->dev, "received invalid command response:"
+			 "got %d, instead of %d\n", len - 4, ar->readlen);
+		print_hex_dump_bytes("carl9170 cmd:", DUMP_PREFIX_OFFSET,
+			ar->cmd_buf, le32_to_cpu(ar->cmd_buf[0]) & 0x3f);
+		print_hex_dump_bytes("carl9170 rsp:", DUMP_PREFIX_OFFSET,
+			buffer, len);
+		/*
+		 * Do not complete. The command times out,
+		 * and we get a stack trace from there.
+		 */
+		carl9170_restart(ar, CARL9170_RR_INVALID_RSP);
+	}
+
+	spin_lock(&ar->cmd_lock);
+	if (ar->readbuf) {
+		if (len >= 4)
+			memcpy(ar->readbuf, buffer + 4, len - 4);
+
+		ar->readbuf = NULL;
+	}
+	complete(&ar->cmd_wait);
+	spin_unlock(&ar->cmd_lock);
+}
+
+void carl9170_handle_command_response(struct ar9170 *ar, void *buf, u32 len)
+{
+	struct carl9170_rsp *cmd = (void *) buf;
+	struct ieee80211_vif *vif;
+
+	if (carl9170_check_sequence(ar, cmd->hdr.seq))
+		return;
+
+	if ((cmd->hdr.cmd & CARL9170_RSP_FLAG) != CARL9170_RSP_FLAG) {
+		if (!(cmd->hdr.cmd & CARL9170_CMD_ASYNC_FLAG))
+			carl9170_cmd_callback(ar, len, buf);
+
+		return;
+	}
+
+	if (unlikely(cmd->hdr.len != (len - 4))) {
+		if (net_ratelimit()) {
+			wiphy_err(ar->hw->wiphy, "FW: received over-/under"
+				"sized event %x (%d, but should be %d).\n",
+			       cmd->hdr.cmd, cmd->hdr.len, len - 4);
+
+			print_hex_dump_bytes("dump:", DUMP_PREFIX_NONE,
+					     buf, len);
+		}
+
+		return;
+	}
+
+	/* hardware event handlers */
+	switch (cmd->hdr.cmd) {
+	case CARL9170_RSP_PRETBTT:
+		/* pre-TBTT event */
+		rcu_read_lock();
+		vif = carl9170_get_main_vif(ar);
+
+		if (!vif) {
+			rcu_read_unlock();
+			break;
+		}
+
+		switch (vif->type) {
+		case NL80211_IFTYPE_STATION:
+			carl9170_handle_ps(ar, cmd);
+			break;
+
+		case NL80211_IFTYPE_AP:
+		case NL80211_IFTYPE_ADHOC:
+			carl9170_update_beacon(ar, true);
+			break;
+
+		default:
+			break;
+		}
+		rcu_read_unlock();
+
+		break;
+
+
+	case CARL9170_RSP_TXCOMP:
+		/* TX status notification */
+		carl9170_tx_process_status(ar, cmd);
+		break;
+
+	case CARL9170_RSP_BEACON_CONFIG:
+		/*
+		 * (IBSS) beacon send notification
+		 * bytes: 04 c2 XX YY B4 B3 B2 B1
+		 *
+		 * XX always 80
+		 * YY always 00
+		 * B1-B4 "should" be the number of send out beacons.
+		 */
+		break;
+
+	case CARL9170_RSP_ATIM:
+		/* End of Atim Window */
+		break;
+
+	case CARL9170_RSP_WATCHDOG:
+		/* Watchdog Interrupt */
+		carl9170_restart(ar, CARL9170_RR_WATCHDOG);
+		break;
+
+	case CARL9170_RSP_TEXT:
+		/* firmware debug */
+		carl9170_dbg_message(ar, (char *)buf + 4, len - 4);
+		break;
+
+	case CARL9170_RSP_HEXDUMP:
+		wiphy_dbg(ar->hw->wiphy, "FW: HD %d\n", len - 4);
+		print_hex_dump_bytes("FW:", DUMP_PREFIX_NONE,
+				     (char *)buf + 4, len - 4);
+		break;
+
+	case CARL9170_RSP_RADAR:
+		if (!net_ratelimit())
+			break;
+
+		wiphy_info(ar->hw->wiphy, "FW: RADAR! Please report this "
+		       "incident to [email protected] !\n");
+		break;
+
+	case CARL9170_RSP_GPIO:
+#ifdef CONFIG_CARL9170_WPS_BUTTON
+		if (ar->wps_pbc) {
+			bool state = !!(cmd->gpio.gpio & cpu_to_le32(
+				AR9170_GPIO_PORT_WPS_BUTTON_PRESSED));
+
+			if (state != ar->wps_pbc_state) {
+				ar->wps_pbc_state = state;
+				input_report_key(ar->wps_pbc, KEY_WPS_BUTTON,
+						 state);
+				input_sync(ar->wps_pbc);
+			}
+		}
+#endif /* CONFIG_CARL9170_WPS_BUTTON */
+		break;
+
+	case CARL9170_RSP_BOOT:
+		complete(&ar->fw_boot_wait);
+		break;
+
+	default:
+		wiphy_err(ar->hw->wiphy, "FW: received unhandled event %x\n",
+			cmd->hdr.cmd);
+		print_hex_dump_bytes("dump:", DUMP_PREFIX_NONE, buf, len);
+		break;
+	}
+}
+
+static int carl9170_rx_mac_status(struct ar9170 *ar,
+	struct ar9170_rx_head *head, struct ar9170_rx_macstatus *mac,
+	struct ieee80211_rx_status *status)
+{
+	struct ieee80211_channel *chan;
+	u8 error, decrypt;
+
+	BUILD_BUG_ON(sizeof(struct ar9170_rx_head) != 12);
+	BUILD_BUG_ON(sizeof(struct ar9170_rx_macstatus) != 4);
+
+	error = mac->error;
+
+	if (error & AR9170_RX_ERROR_WRONG_RA) {
+		if (!ar->sniffer_enabled)
+			return -EINVAL;
+	}
+
+	if (error & AR9170_RX_ERROR_PLCP) {
+		if (!(ar->filter_state & FIF_PLCPFAIL))
+			return -EINVAL;
+
+		status->flag |= RX_FLAG_FAILED_PLCP_CRC;
+	}
+
+	if (error & AR9170_RX_ERROR_FCS) {
+		ar->tx_fcs_errors++;
+
+		if (!(ar->filter_state & FIF_FCSFAIL))
+			return -EINVAL;
+
+		status->flag |= RX_FLAG_FAILED_FCS_CRC;
+	}
+
+	decrypt = ar9170_get_decrypt_type(mac);
+	if (!(decrypt & AR9170_RX_ENC_SOFTWARE) &&
+	    decrypt != AR9170_ENC_ALG_NONE) {
+		if ((decrypt == AR9170_ENC_ALG_TKIP) &&
+		    (error & AR9170_RX_ERROR_MMIC))
+			status->flag |= RX_FLAG_MMIC_ERROR;
+
+		status->flag |= RX_FLAG_DECRYPTED;
+	}
+
+	if (error & AR9170_RX_ERROR_DECRYPT && !ar->sniffer_enabled)
+		return -ENODATA;
+
+	error &= ~(AR9170_RX_ERROR_MMIC |
+		   AR9170_RX_ERROR_FCS |
+		   AR9170_RX_ERROR_WRONG_RA |
+		   AR9170_RX_ERROR_DECRYPT |
+		   AR9170_RX_ERROR_PLCP);
+
+	/* drop any other error frames */
+	if (unlikely(error)) {
+		/* TODO: update netdevice's RX dropped/errors statistics */
+
+		if (net_ratelimit())
+			wiphy_dbg(ar->hw->wiphy, "received frame with "
+			       "suspicious error code (%#x).\n", error);
+
+		return -EINVAL;
+	}
+
+	chan = ar->channel;
+	if (chan) {
+		status->band = chan->band;
+		status->freq = chan->center_freq;
+	}
+
+	switch (mac->status & AR9170_RX_STATUS_MODULATION) {
+	case AR9170_RX_STATUS_MODULATION_CCK:
+		if (mac->status & AR9170_RX_STATUS_SHORT_PREAMBLE)
+			status->flag |= RX_FLAG_SHORTPRE;
+		switch (head->plcp[0]) {
+		case AR9170_RX_PHY_RATE_CCK_1M:
+			status->rate_idx = 0;
+			break;
+		case AR9170_RX_PHY_RATE_CCK_2M:
+			status->rate_idx = 1;
+			break;
+		case AR9170_RX_PHY_RATE_CCK_5M:
+			status->rate_idx = 2;
+			break;
+		case AR9170_RX_PHY_RATE_CCK_11M:
+			status->rate_idx = 3;
+			break;
+		default:
+			if (net_ratelimit()) {
+				wiphy_err(ar->hw->wiphy, "invalid plcp cck "
+				       "rate (%x).\n", head->plcp[0]);
+			}
+
+			return -EINVAL;
+		}
+		break;
+
+	case AR9170_RX_STATUS_MODULATION_DUPOFDM:
+	case AR9170_RX_STATUS_MODULATION_OFDM:
+		switch (head->plcp[0] & 0xf) {
+		case AR9170_TXRX_PHY_RATE_OFDM_6M:
+			status->rate_idx = 0;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_9M:
+			status->rate_idx = 1;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_12M:
+			status->rate_idx = 2;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_18M:
+			status->rate_idx = 3;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_24M:
+			status->rate_idx = 4;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_36M:
+			status->rate_idx = 5;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_48M:
+			status->rate_idx = 6;
+			break;
+		case AR9170_TXRX_PHY_RATE_OFDM_54M:
+			status->rate_idx = 7;
+			break;
+		default:
+			if (net_ratelimit()) {
+				wiphy_err(ar->hw->wiphy, "invalid plcp ofdm "
+					"rate (%x).\n", head->plcp[0]);
+			}
+
+			return -EINVAL;
+		}
+		if (status->band == IEEE80211_BAND_2GHZ)
+			status->rate_idx += 4;
+		break;
+
+	case AR9170_RX_STATUS_MODULATION_HT:
+		if (head->plcp[3] & 0x80)
+			status->flag |= RX_FLAG_40MHZ;
+		if (head->plcp[6] & 0x80)
+			status->flag |= RX_FLAG_SHORT_GI;
+
+		status->rate_idx = clamp(0, 75, head->plcp[3] & 0x7f);
+		status->flag |= RX_FLAG_HT;
+		break;
+
+	default:
+		if (net_ratelimit())
+			wiphy_err(ar->hw->wiphy, "invalid modulation\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void carl9170_rx_phy_status(struct ar9170 *ar,
+	struct ar9170_rx_phystatus *phy, struct ieee80211_rx_status *status)
+{
+	int i;
+
+	BUILD_BUG_ON(sizeof(struct ar9170_rx_phystatus) != 20);
+
+	for (i = 0; i < 3; i++)
+		if (phy->rssi[i] != 0x80)
+			status->antenna |= BIT(i);
+
+	/* post-process RSSI */
+	for (i = 0; i < 7; i++)
+		if (phy->rssi[i] & 0x80)
+			phy->rssi[i] = ((phy->rssi[i] & 0x7f) + 1) & 0x7f;
+
+	/* TODO: we could do something with phy_errors */
+	status->signal = ar->noise[0] + phy->rssi_combined;
+}
+
+static struct sk_buff *carl9170_rx_copy_data(u8 *buf, int len)
+{
+	struct sk_buff *skb;
+	int reserved = 0;
+	struct ieee80211_hdr *hdr = (void *) buf;
+
+	if (ieee80211_is_data_qos(hdr->frame_control)) {
+		u8 *qc = ieee80211_get_qos_ctl(hdr);
+		reserved += NET_IP_ALIGN;
+
+		if (*qc & IEEE80211_QOS_CONTROL_A_MSDU_PRESENT)
+			reserved += NET_IP_ALIGN;
+	}
+
+	if (ieee80211_has_a4(hdr->frame_control))
+		reserved += NET_IP_ALIGN;
+
+	reserved = 32 + (reserved & NET_IP_ALIGN);
+
+	skb = dev_alloc_skb(len + reserved);
+	if (likely(skb)) {
+		skb_reserve(skb, reserved);
+		memcpy(skb_put(skb, len), buf, len);
+	}
+
+	return skb;
+}
+
+static u8 *carl9170_find_ie(void *data, unsigned int len, u8 ie)
+{
+	struct ieee80211_mgmt *mgmt = (void *)data;
+	u8 *pos, *end;
+
+	pos = (u8 *)mgmt->u.beacon.variable;
+	end = data + len;
+	while (pos < end) {
+		if (pos + 2 + pos[1] > end)
+			return NULL;
+
+		if (pos[0] == ie)
+			return pos;
+
+		pos += 2 + pos[1];
+	}
+	return NULL;
+}
+
+/*
+ * NOTE:
+ *
+ * The firmware is in charge of waking up the device just before
+ * the AP is expected to transmit the next beacon.
+ *
+ * This leaves the driver with the important task of deciding when
+ * to set the PHY back to bed again.
+ */
+static void carl9170_ps_beacon(struct ar9170 *ar, void *data, unsigned int len)
+{
+	struct ieee80211_hdr *hdr = (void *) data;
+	struct ieee80211_tim_ie *tim_ie;
+	u8 *tim;
+	u8 tim_len;
+	bool cam;
+
+	if (likely(!(ar->hw->conf.flags & IEEE80211_CONF_PS)))
+		return;
+
+	/* check if this really is a beacon */
+	if (!ieee80211_is_beacon(hdr->frame_control))
+		return;
+
+	/* min. beacon length + FCS_LEN */
+	if (len <= 40 + FCS_LEN)
+		return;
+
+	/* and only beacons from the associated BSSID, please */
+	if (compare_ether_addr(hdr->addr3, ar->common.curbssid) ||
+	    !ar->common.curaid)
+		return;
+
+	ar->ps_last_beacon = jiffies;
+
+	tim = carl9170_find_ie(data, len - FCS_LEN, WLAN_EID_TIM);
+	if (!tim)
+		return;
+
+	if (tim[1] < sizeof(*tim_ie))
+		return;
+
+	tim_len = tim[1];
+	tim_ie = (struct ieee80211_tim_ie *) &tim[2];
+
+	if (!WARN_ON_ONCE(!ar->hw->conf.ps_dtim_period))
+		ar->ps_dtim_counter = (tim_ie->dtim_count - 1) %
+			ar->hw->conf.ps_dtim_period;
+
+	/* Check whenever the PHY can be turned off again. */
+
+	/* 1. What about buffered unicast traffic for our AID? */
+	cam = ieee80211_check_tim(tim_ie, tim_len, ar->common.curaid);
+
+	/* 2. Maybe the AP wants to send multicast/broadcast data? */
+	cam = !!(tim_ie->bitmap_ctrl & 0x01);
+
+	if (!cam) {
+		/* back to low-power land. */
+		ar->ps_off_override &= ~PS_OFF_BCN;
+		carl9170_ps_check(ar);
+	} else {
+		/* force CAM */
+		ar->ps_off_override |= PS_OFF_BCN;
+	}
+}
+
+/*
+ * If the frame alignment is right (or the kernel has
+ * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS), and there
+ * is only a single MPDU in the USB frame, then we could
+ * submit to mac80211 the SKB directly. However, since
+ * there may be multiple packets in one SKB in stream
+ * mode, and we need to observe the proper ordering,
+ * this is non-trivial.
+ */
+
+static void carl9170_handle_mpdu(struct ar9170 *ar, u8 *buf, int len)
+{
+	struct ar9170_rx_head *head;
+	struct ar9170_rx_macstatus *mac;
+	struct ar9170_rx_phystatus *phy = NULL;
+	struct ieee80211_rx_status status;
+	struct sk_buff *skb;
+	int mpdu_len;
+
+	if (!IS_STARTED(ar))
+		return;
+
+	if (unlikely(len < sizeof(*mac))) {
+		ar->rx_dropped++;
+		return;
+	}
+
+	mpdu_len = len - sizeof(*mac);
+
+	mac = (void *)(buf + mpdu_len);
+	if (unlikely(mac->error & AR9170_RX_ERROR_FATAL)) {
+		ar->rx_dropped++;
+		return;
+	}
+
+	switch (mac->status & AR9170_RX_STATUS_MPDU) {
+	case AR9170_RX_STATUS_MPDU_FIRST:
+		/* Aggregated MPDUs start with an PLCP header */
+		if (likely(mpdu_len >= sizeof(struct ar9170_rx_head))) {
+			head = (void *) buf;
+
+			/*
+			 * The PLCP header needs to be cached for the
+			 * following MIDDLE + LAST A-MPDU packets.
+			 *
+			 * So, if you are wondering why all frames seem
+			 * to share a common RX status information,
+			 * then you have the answer right here...
+			 */
+			memcpy(&ar->rx_plcp, (void *) buf,
+			       sizeof(struct ar9170_rx_head));
+
+			mpdu_len -= sizeof(struct ar9170_rx_head);
+			buf += sizeof(struct ar9170_rx_head);
+
+			ar->rx_has_plcp = true;
+		} else {
+			if (net_ratelimit()) {
+				wiphy_err(ar->hw->wiphy, "plcp info "
+					"is clipped.\n");
+			}
+
+			ar->rx_dropped++;
+			return;
+		}
+		break;
+
+	case AR9170_RX_STATUS_MPDU_LAST:
+		/*
+		 * The last frame of an A-MPDU has an extra tail
+		 * which does contain the phy status of the whole
+		 * aggregate.
+		 */
+
+		if (likely(mpdu_len >= sizeof(struct ar9170_rx_phystatus))) {
+			mpdu_len -= sizeof(struct ar9170_rx_phystatus);
+			phy = (void *)(buf + mpdu_len);
+		} else {
+			if (net_ratelimit()) {
+				wiphy_err(ar->hw->wiphy, "frame tail "
+					"is clipped.\n");
+			}
+
+			ar->rx_dropped++;
+			return;
+		}
+
+	case AR9170_RX_STATUS_MPDU_MIDDLE:
+		/*  These are just data + mac status */
+		if (unlikely(!ar->rx_has_plcp)) {
+			if (!net_ratelimit())
+				return;
+
+			wiphy_err(ar->hw->wiphy, "rx stream does not start "
+					"with a first_mpdu frame tag.\n");
+
+			ar->rx_dropped++;
+			return;
+		}
+
+		head = &ar->rx_plcp;
+		break;
+
+	case AR9170_RX_STATUS_MPDU_SINGLE:
+		/* single mpdu has both: plcp (head) and phy status (tail) */
+		head = (void *) buf;
+
+		mpdu_len -= sizeof(struct ar9170_rx_head);
+		mpdu_len -= sizeof(struct ar9170_rx_phystatus);
+
+		buf += sizeof(struct ar9170_rx_head);
+		phy = (void *)(buf + mpdu_len);
+		break;
+
+	default:
+		BUG_ON(1);
+		break;
+	}
+
+	/* FC + DU + RA + FCS */
+	if (unlikely(mpdu_len < (2 + 2 + 6 + FCS_LEN))) {
+		ar->rx_dropped++;
+		return;
+	}
+
+	memset(&status, 0, sizeof(status));
+	if (unlikely(carl9170_rx_mac_status(ar, head, mac, &status))) {
+		ar->rx_dropped++;
+		return;
+	}
+
+	if (phy)
+		carl9170_rx_phy_status(ar, phy, &status);
+
+	carl9170_ps_beacon(ar, buf, mpdu_len);
+
+	skb = carl9170_rx_copy_data(buf, mpdu_len);
+	if (likely(skb)) {
+		memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
+		ieee80211_rx(ar->hw, skb);
+	} else {
+		ar->rx_dropped++;
+	}
+}
+
+static void carl9170_rx_untie_cmds(struct ar9170 *ar, const u8 *respbuf,
+				   const unsigned int resplen)
+{
+	struct carl9170_rsp *cmd;
+	int i = 0;
+
+	while (i < resplen) {
+		cmd = (void *) &respbuf[i];
+
+		i += cmd->hdr.len + 4;
+		if (unlikely(i > resplen))
+			break;
+
+		carl9170_handle_command_response(ar, cmd, cmd->hdr.len + 4);
+	}
+
+	if (unlikely(i != resplen)) {
+		if (!net_ratelimit())
+			return;
+
+		wiphy_err(ar->hw->wiphy, "malformed firmware trap:\n");
+		print_hex_dump_bytes("rxcmd:", DUMP_PREFIX_OFFSET,
+				     respbuf, resplen);
+	}
+}
+
+static void __carl9170_rx(struct ar9170 *ar, u8 *buf, unsigned int len)
+{
+	unsigned int i = 0;
+
+	/* weird thing, but this is the same in the original driver */
+	while (len > 2 && i < 12 && buf[0] == 0xff && buf[1] == 0xff) {
+		i += 2;
+		len -= 2;
+		buf += 2;
+	}
+
+	if (unlikely(len < 4))
+		return;
+
+	/* found the 6 * 0xffff marker? */
+	if (i == 12)
+		carl9170_rx_untie_cmds(ar, buf, len);
+	else
+		carl9170_handle_mpdu(ar, buf, len);
+}
+
+static void carl9170_rx_stream(struct ar9170 *ar, void *buf, unsigned int len)
+{
+	unsigned int tlen, wlen = 0, clen = 0;
+	struct ar9170_stream *rx_stream;
+	u8 *tbuf;
+
+	tbuf = buf;
+	tlen = len;
+
+	while (tlen >= 4) {
+		rx_stream = (void *) tbuf;
+		clen = le16_to_cpu(rx_stream->length);
+		wlen = ALIGN(clen, 4);
+
+		/* check if this is stream has a valid tag.*/
+		if (rx_stream->tag != cpu_to_le16(AR9170_RX_STREAM_TAG)) {
+			/*
+			 * TODO: handle the highly unlikely event that the
+			 * corrupted stream has the TAG at the right position.
+			 */
+
+			/* check if the frame can be repaired. */
+			if (!ar->rx_failover_missing) {
+
+				/* this is not "short read". */
+				if (net_ratelimit()) {
+					wiphy_err(ar->hw->wiphy,
+						"missing tag!\n");
+				}
+
+				__carl9170_rx(ar, tbuf, tlen);
+				return;
+			}
+
+			if (ar->rx_failover_missing > tlen) {
+				if (net_ratelimit()) {
+					wiphy_err(ar->hw->wiphy,
+						"possible multi "
+						"stream corruption!\n");
+					goto err_telluser;
+				} else {
+					goto err_silent;
+				}
+			}
+
+			memcpy(skb_put(ar->rx_failover, tlen), tbuf, tlen);
+			ar->rx_failover_missing -= tlen;
+
+			if (ar->rx_failover_missing <= 0) {
+				/*
+				 * nested carl9170_rx_stream call!
+				 *
+				 * termination is guranteed, even when the
+				 * combined frame also have an element with
+				 * a bad tag.
+				 */
+
+				ar->rx_failover_missing = 0;
+				carl9170_rx_stream(ar, ar->rx_failover->data,
+						   ar->rx_failover->len);
+
+				skb_reset_tail_pointer(ar->rx_failover);
+				skb_trim(ar->rx_failover, 0);
+			}
+
+			return;
+		}
+
+		/* check if stream is clipped */
+		if (wlen > tlen - 4) {
+			if (ar->rx_failover_missing) {
+				/* TODO: handle double stream corruption. */
+				if (net_ratelimit()) {
+					wiphy_err(ar->hw->wiphy, "double rx "
+						"stream corruption!\n");
+					goto err_telluser;
+				} else {
+					goto err_silent;
+				}
+			}
+
+			/*
+			 * save incomplete data set.
+			 * the firmware will resend the missing bits when
+			 * the rx - descriptor comes round again.
+			 */
+
+			memcpy(skb_put(ar->rx_failover, tlen), tbuf, tlen);
+			ar->rx_failover_missing = clen - tlen;
+			return;
+		}
+		__carl9170_rx(ar, rx_stream->payload, clen);
+
+		tbuf += wlen + 4;
+		tlen -= wlen + 4;
+	}
+
+	if (tlen) {
+		if (net_ratelimit()) {
+			wiphy_err(ar->hw->wiphy, "%d bytes of unprocessed "
+				"data left in rx stream!\n", tlen);
+		}
+
+		goto err_telluser;
+	}
+
+	return;
+
+err_telluser:
+	wiphy_err(ar->hw->wiphy, "damaged RX stream data [want:%d, "
+		"data:%d, rx:%d, pending:%d ]\n", clen, wlen, tlen,
+		ar->rx_failover_missing);
+
+	if (ar->rx_failover_missing)
+		print_hex_dump_bytes("rxbuf:", DUMP_PREFIX_OFFSET,
+				     ar->rx_failover->data,
+				     ar->rx_failover->len);
+
+	print_hex_dump_bytes("stream:", DUMP_PREFIX_OFFSET,
+			     buf, len);
+
+	wiphy_err(ar->hw->wiphy, "please check your hardware and cables, if "
+		"you see this message frequently.\n");
+
+err_silent:
+	if (ar->rx_failover_missing) {
+		skb_reset_tail_pointer(ar->rx_failover);
+		skb_trim(ar->rx_failover, 0);
+		ar->rx_failover_missing = 0;
+	}
+}
+
+void carl9170_rx(struct ar9170 *ar, void *buf, unsigned int len)
+{
+	if (ar->rx_stream)
+		carl9170_rx_stream(ar, buf, len);
+	else
+		__carl9170_rx(ar, buf, len);
+}

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