path: root/drivers/net/wireless/mwifiex/main.c

/*
 * Marvell Wireless LAN device driver: major functions
 *
 * Copyright (C) 2011, Marvell International Ltd.
 *
 * This software file (the "File") is distributed by Marvell International
 * Ltd. under the terms of the GNU General Public License Version 2, June 1991
 * (the "License").  You may use, redistribute and/or modify this File in
 * accordance with the terms and conditions of the License, a copy of which
 * is available by writing to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or on the
 * worldwide web at http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
 *
 * THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
 * ARE EXPRESSLY DISCLAIMED.  The License provides additional details about
 * this warranty disclaimer.
 */

#include "main.h"
#include "wmm.h"
#include "cfg80211.h"
#include "11n.h"

#define VERSION	"1.0"

const char driver_version[] = "mwifiex " VERSION " (%s) ";

/*
 * This function registers the device and performs all the necessary
 * initializations.
 *
 * The following initialization operations are performed -
 *      - Allocate adapter structure
 *      - Save interface specific operations table in adapter
 *      - Call interface specific initialization routine
 *      - Allocate private structures
 *      - Set default adapter structure parameters
 *      - Initialize locks
 *
 * In case of any errors during inittialization, this function also ensures
 * proper cleanup before exiting.
 */
static int mwifiex_register(void *card, struct mwifiex_if_ops *if_ops,
			    void **padapter)
{
	struct mwifiex_adapter *adapter;
	int i;

	adapter = kzalloc(sizeof(struct mwifiex_adapter), GFP_KERNEL);
	if (!adapter)
		return -ENOMEM;

	*padapter = adapter;
	adapter->card = card;

	/* Save interface specific operations in adapter */
	memmove(&adapter->if_ops, if_ops, sizeof(struct mwifiex_if_ops));

	/* card specific initialization has been deferred until now .. */
	if (adapter->if_ops.init_if(adapter))
		goto error;

	adapter->priv_num = 0;

	/* Allocate memory for private structure */
	adapter->priv[0] = kzalloc(sizeof(struct mwifiex_private),
			GFP_KERNEL);
	if (!adapter->priv[0]) {
		dev_err(adapter->dev, "%s: failed to alloc priv[0]\n",
		       __func__);
		goto error;
	}

	adapter->priv_num++;

	adapter->priv[0]->adapter = adapter;
	mwifiex_init_lock_list(adapter);

	init_timer(&adapter->cmd_timer);
	adapter->cmd_timer.function = mwifiex_cmd_timeout_func;
	adapter->cmd_timer.data = (unsigned long) adapter;

	return 0;

error:
	dev_dbg(adapter->dev, "info: leave mwifiex_register with error\n");

	for (i = 0; i < adapter->priv_num; i++)
		kfree(adapter->priv[i]);

	kfree(adapter);

	return -1;
}

/*
 * This function unregisters the device and performs all the necessary
 * cleanups.
 *
 * The following cleanup operations are performed -
 *      - Free the timers
 *      - Free beacon buffers
 *      - Free private structures
 *      - Free adapter structure
 */
static int mwifiex_unregister(struct mwifiex_adapter *adapter)
{
	s32 i;

	del_timer(&adapter->cmd_timer);

	/* Free private structures */
	for (i = 0; i < adapter->priv_num; i++) {
		if (adapter->priv[i]) {
			mwifiex_free_curr_bcn(adapter->priv[i]);
			kfree(adapter->priv[i]);
		}
	}

	kfree(adapter);
	return 0;
}

/*
 * The main process.
 *
 * This function is the main procedure of the driver and handles various driver
 * operations. It runs in a loop and provides the core functionalities.
 *
 * The main responsibilities of this function are -
 *      - Ensure concurrency control
 *      - Handle pending interrupts and call interrupt handlers
 *      - Wake up the card if required
 *      - Handle command responses and call response handlers
 *      - Handle events and call event handlers
 *      - Execute pending commands
 *      - Transmit pending data packets
 */
int mwifiex_main_process(struct mwifiex_adapter *adapter)
{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&adapter->main_proc_lock, flags);

	/* Check if already processing */
	if (adapter->mwifiex_processing) {
		spin_unlock_irqrestore(&adapter->main_proc_lock, flags);
		goto exit_main_proc;
	} else {
		adapter->mwifiex_processing = true;
		spin_unlock_irqrestore(&adapter->main_proc_lock, flags);
	}
process_start:
	do {
		if ((adapter->hw_status == MWIFIEX_HW_STATUS_CLOSING) ||
		    (adapter->hw_status == MWIFIEX_HW_STATUS_NOT_READY))
			break;

		/* Handle pending interrupt if any */
		if (adapter->int_status) {
			if (adapter->hs_activated)
				mwifiex_process_hs_config(adapter);
			adapter->if_ops.process_int_status(adapter);
		}

		/* Need to wake up the card ? */
		if ((adapter->ps_state == PS_STATE_SLEEP) &&
		    (adapter->pm_wakeup_card_req &&
		     !adapter->pm_wakeup_fw_try) &&
		    (is_command_pending(adapter)
		     || !mwifiex_wmm_lists_empty(adapter))) {
			adapter->pm_wakeup_fw_try = true;
			adapter->if_ops.wakeup(adapter);
			continue;
		}
		if (IS_CARD_RX_RCVD(adapter)) {
			adapter->pm_wakeup_fw_try = false;
			if (adapter->ps_state == PS_STATE_SLEEP)
				adapter->ps_state = PS_STATE_AWAKE;
		} else {
			/* We have tried to wakeup the card already */
			if (adapter->pm_wakeup_fw_try)
				break;
			if (adapter->ps_state != PS_STATE_AWAKE ||
			    adapter->tx_lock_flag)
				break;

			if (adapter->scan_processing || adapter->data_sent
			    || mwifiex_wmm_lists_empty(adapter)) {
				if (adapter->cmd_sent || adapter->curr_cmd
				    || (!is_command_pending(adapter)))
					break;
			}
		}

		/* Check for Cmd Resp */
		if (adapter->cmd_resp_received) {
			adapter->cmd_resp_received = false;
			mwifiex_process_cmdresp(adapter);

			/* call mwifiex back when init_fw is done */
			if (adapter->hw_status == MWIFIEX_HW_STATUS_INIT_DONE) {
				adapter->hw_status = MWIFIEX_HW_STATUS_READY;
				mwifiex_init_fw_complete(adapter);
			}
		}

		/* Check for event */
		if (adapter->event_received) {
			adapter->event_received = false;
			mwifiex_process_event(adapter);
		}

		/* Check if we need to confirm Sleep Request
		   received previously */
		if (adapter->ps_state == PS_STATE_PRE_SLEEP) {
			if (!adapter->cmd_sent && !adapter->curr_cmd)
				mwifiex_check_ps_cond(adapter);
		}

		/* * The ps_state may have been changed during processing of
		 * Sleep Request event.
		 */
		if ((adapter->ps_state == PS_STATE_SLEEP)
		    || (adapter->ps_state == PS_STATE_PRE_SLEEP)
		    || (adapter->ps_state == PS_STATE_SLEEP_CFM)
		    || adapter->tx_lock_flag)
			continue;

		if (!adapter->cmd_sent && !adapter->curr_cmd) {
			if (mwifiex_exec_next_cmd(adapter) == -1) {
				ret = -1;
				break;
			}
		}

		if (!adapter->scan_processing && !adapter->data_sent &&
		    !mwifiex_wmm_lists_empty(adapter)) {
			mwifiex_wmm_process_tx(adapter);
			if (adapter->hs_activated) {
				adapter->is_hs_configured = false;
				mwifiex_hs_activated_event
					(mwifiex_get_priv
					 (adapter, MWIFIEX_BSS_ROLE_ANY),
					 false);
			}
		}

		if (adapter->delay_null_pkt && !adapter->cmd_sent &&
		    !adapter->curr_cmd && !is_command_pending(adapter)
		    && mwifiex_wmm_lists_empty(adapter)) {
			if (!mwifiex_send_null_packet
			    (mwifiex_get_priv(adapter, MWIFIEX_BSS_ROLE_STA),
			     MWIFIEX_TxPD_POWER_MGMT_NULL_PACKET |
			     MWIFIEX_TxPD_POWER_MGMT_LAST_PACKET)) {
				adapter->delay_null_pkt = false;
				adapter->ps_state = PS_STATE_SLEEP;
			}
			break;
		}
	} while (true);

	if ((adapter->int_status) || IS_CARD_RX_RCVD(adapter))
		goto process_start;

	spin_lock_irqsave(&adapter->main_proc_lock, flags);
	adapter->mwifiex_processing = false;
	spin_unlock_irqrestore(&adapter->main_proc_lock, flags);

exit_main_proc:
	if (adapter->hw_status == MWIFIEX_HW_STATUS_CLOSING)
		mwifiex_shutdown_drv(adapter);
	return ret;
}

/*
 * This function frees the adapter structure.
 *
 * Additionally, this closes the netlink socket, frees the timers
 * and private structures.
 */
static void mwifiex_free_adapter(struct mwifiex_adapter *adapter)
{
	if (!adapter) {
		pr_err("%s: adapter is NULL\n", __func__);
		return;
	}

	mwifiex_unregister(adapter);
	pr_debug("info: %s: free adapter\n", __func__);
}

/*
 * This function initializes the hardware and firmware.
 *
 * The main initialization steps followed are -
 *      - Download the correct firmware to card
 *      - Allocate and initialize the adapter structure
 *      - Initialize the private structures
 *      - Issue the init commands to firmware
 */
static int mwifiex_init_hw_fw(struct mwifiex_adapter *adapter)
{
	int ret, err;
	struct mwifiex_fw_image fw;

	memset(&fw, 0, sizeof(struct mwifiex_fw_image));

	err = request_firmware(&adapter->firmware, adapter->fw_name,
			       adapter->dev);
	if (err < 0) {
		dev_err(adapter->dev, "request_firmware() returned"
				" error code %#x\n", err);
		ret = -1;
		goto done;
	}
	fw.fw_buf = (u8 *) adapter->firmware->data;
	fw.fw_len = adapter->firmware->size;

	ret = mwifiex_dnld_fw(adapter, &fw);
	if (ret == -1)
		goto done;

	dev_notice(adapter->dev, "WLAN FW is active\n");

	adapter->init_wait_q_woken = false;
	ret = mwifiex_init_fw(adapter);
	if (ret == -1) {
		goto done;
	} else if (!ret) {
		adapter->hw_status = MWIFIEX_HW_STATUS_READY;
		goto done;
	}
	/* Wait for mwifiex_init to complete */
	wait_event_interruptible(adapter->init_wait_q,
				 adapter->init_wait_q_woken);
	if (adapter->hw_status != MWIFIEX_HW_STATUS_READY) {
		ret = -1;
		goto done;
	}
	ret = 0;

done:
	if (adapter->firmware)
		release_firmware(adapter->firmware);
	if (ret)
		ret = -1;
	return ret;
}

/*
 * This function fills a driver buffer.
 *
 * The function associates a given SKB with the provided driver buffer
 * and also updates some of the SKB parameters, including IP header,
 * priority and timestamp.
 */
static void
mwifiex_fill_buffer(struct sk_buff *skb)
{
	struct ethhdr *eth;
	struct iphdr *iph;
	struct timeval tv;
	u8 tid = 0;

	eth = (struct ethhdr *) skb->data;
	switch (eth->h_proto) {
	case __constant_htons(ETH_P_IP):
		iph = ip_hdr(skb);
		tid = IPTOS_PREC(iph->tos);
		pr_debug("data: packet type ETH_P_IP: %04x, tid=%#x prio=%#x\n",
		       eth->h_proto, tid, skb->priority);
		break;
	case __constant_htons(ETH_P_ARP):
		pr_debug("data: ARP packet: %04x\n", eth->h_proto);
	default:
		break;
	}
/* Offset for TOS field in the IP header */
#define IPTOS_OFFSET 5
	tid = (tid >> IPTOS_OFFSET);
	skb->priority = tid;
	/* Record the current time the packet was queued; used to
	   determine the amount of time the packet was queued in
	   the driver before it was sent to the firmware.
	   The delay is then sent along with the packet to the
	   firmware for aggregate delay calculation for stats and
	   MSDU lifetime expiry.
	 */
	do_gettimeofday(&tv);
	skb->tstamp = timeval_to_ktime(tv);
}

/*
 * CFG802.11 network device handler for open.
 *
 * Starts the data queue.
 */
static int
mwifiex_open(struct net_device *dev)
{
	netif_tx_start_all_queues(dev);
	return 0;
}

/*
 * CFG802.11 network device handler for close.
 */
static int
mwifiex_close(struct net_device *dev)
{
	return 0;
}

/*
 * CFG802.11 network device handler for data transmission.
 */
static int
mwifiex_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct mwifiex_private *priv = mwifiex_netdev_get_priv(dev);
	struct sk_buff *new_skb;
	struct mwifiex_txinfo *tx_info;

	dev_dbg(priv->adapter->dev, "data: %lu BSS(%d): Data <= kernel\n",
				jiffies, priv->bss_index);

	if (priv->adapter->surprise_removed) {
		kfree_skb(skb);
		priv->stats.tx_dropped++;
		return 0;
	}
	if (!skb->len || (skb->len > ETH_FRAME_LEN)) {
		dev_err(priv->adapter->dev, "Tx: bad skb len %d\n", skb->len);
		kfree_skb(skb);
		priv->stats.tx_dropped++;
		return 0;
	}
	if (skb_headroom(skb) < MWIFIEX_MIN_DATA_HEADER_LEN) {
		dev_dbg(priv->adapter->dev,
			"data: Tx: insufficient skb headroom %d\n",
		       skb_headroom(skb));
		/* Insufficient skb headroom - allocate a new skb */
		new_skb =
			skb_realloc_headroom(skb, MWIFIEX_MIN_DATA_HEADER_LEN);
		if (unlikely(!new_skb)) {
			dev_err(priv->adapter->dev, "Tx: cannot alloca new_skb\n");
			kfree_skb(skb);
			priv->stats.tx_dropped++;
			return 0;
		}
		kfree_skb(skb);
		skb = new_skb;
		dev_dbg(priv->adapter->dev, "info: new skb headroomd %d\n",
				skb_headroom(skb));
	}

	tx_info = MWIFIEX_SKB_TXCB(skb);
	tx_info->bss_index = priv->bss_index;
	mwifiex_fill_buffer(skb);

	mwifiex_wmm_add_buf_txqueue(priv->adapter, skb);
	atomic_inc(&priv->adapter->tx_pending);

	if (atomic_read(&priv->adapter->tx_pending) >= MAX_TX_PENDING) {
		mwifiex_set_trans_start(dev);
		mwifiex_stop_net_dev_queue(priv->netdev, priv->adapter);
	}

	queue_work(priv->adapter->workqueue, &priv->adapter->main_work);

	return 0;
}

/*
 * CFG802.11 network device handler for setting MAC address.
 */
static int
mwifiex_set_mac_address(struct net_device *dev, void *addr)
{
	struct mwifiex_private *priv = mwifiex_netdev_get_priv(dev);
	struct sockaddr *hw_addr = addr;
	int ret;

	memcpy(priv->curr_addr, hw_addr->sa_data, ETH_ALEN);

	/* Send request to firmware */
	ret = mwifiex_send_cmd_sync(priv, HostCmd_CMD_802_11_MAC_ADDRESS,
				    HostCmd_ACT_GEN_SET, 0, NULL);

	if (!ret)
		memcpy(priv->netdev->dev_addr, priv->curr_addr, ETH_ALEN);
	else
		dev_err(priv->adapter->dev, "set mac address failed: ret=%d"
					    "\n", ret);

	memcpy(dev->dev_addr, priv->curr_addr, ETH_ALEN);

	return ret;
}

/*
 * CFG802.11 network device handler for setting multicast list.
 */
static void mwifiex_set_multicast_list(struct net_device *dev)
{
	struct mwifiex_private *priv = mwifiex_netdev_get_priv(dev);
	struct mwifiex_multicast_list mcast_list;

	if (dev->flags & IFF_PROMISC) {
		mcast_list.mode = MWIFIEX_PROMISC_MODE;
	} else if (dev->flags & IFF_ALLMULTI ||
		   netdev_mc_count(dev) > MWIFIEX_MAX_MULTICAST_LIST_SIZE) {
		mcast_list.mode = MWIFIEX_ALL_MULTI_MODE;
	} else {
		mcast_list.mode = MWIFIEX_MULTICAST_MODE;
		if (netdev_mc_count(dev))
			mcast_list.num_multicast_addr =
				mwifiex_copy_mcast_addr(&mcast_list, dev);
	}
	mwifiex_request_set_multicast_list(priv, &mcast_list);
}

/*
 * CFG802.11 network device handler for transmission timeout.
 */
static void
mwifiex_tx_timeout(struct net_device *dev)
{
	struct mwifiex_private *priv = mwifiex_netdev_get_priv(dev);

	dev_err(priv->adapter->dev, "%lu : Tx timeout, bss_index=%d\n",
				jiffies, priv->bss_index);
	mwifiex_set_trans_start(dev);
	priv->num_tx_timeout++;
}

/*
 * CFG802.11 network device handler for statistics retrieval.
 */
static struct net_device_stats *mwifiex_get_stats(struct net_device *dev)
{
	struct mwifiex_private *priv = mwifiex_netdev_get_priv(dev);

	return &priv->stats;
}

/* Network device handlers */
static const struct net_device_ops mwifiex_netdev_ops = {
	.ndo_open = mwifiex_open,
	.ndo_stop = mwifiex_close,
	.ndo_start_xmit = mwifiex_hard_start_xmit,
	.ndo_set_mac_address = mwifiex_set_mac_address,
	.ndo_tx_timeout = mwifiex_tx_timeout,
	.ndo_get_stats = mwifiex_get_stats,
	.ndo_set_rx_mode = mwifiex_set_multicast_list,
};

/*
 * This function initializes the private structure parameters.
 *
 * The following wait queues are initialized -
 *      - IOCTL wait queue
 *      - Command wait queue
 *      - Statistics wait queue
 *
 * ...and the following default parameters are set -
 *      - Current key index     : Set to 0
 *      - Rate index            : Set to auto
 *      - Media connected       : Set to disconnected
 *      - Adhoc link sensed     : Set to false
 *      - Nick name             : Set to null
 *      - Number of Tx timeout  : Set to 0
 *      - Device address        : Set to current address
 *
 * In addition, the CFG80211 work queue is also created.
 */
void mwifiex_init_priv_params(struct mwifiex_private *priv,
						struct net_device *dev)
{
	dev->netdev_ops = &mwifiex_netdev_ops;
	/* Initialize private structure */
	priv->current_key_index = 0;
	priv->media_connected = false;
	memset(&priv->nick_name, 0, sizeof(priv->nick_name));
	priv->num_tx_timeout = 0;
	memcpy(dev->dev_addr, priv->curr_addr, ETH_ALEN);
}

/*
 * This function check if command is pending.
 */
int is_command_pending(struct mwifiex_adapter *adapter)
{
	unsigned long flags;
	int is_cmd_pend_q_empty;

	spin_lock_irqsave(&adapter->cmd_pending_q_lock, flags);
	is_cmd_pend_q_empty = list_empty(&adapter->cmd_pending_q);
	spin_unlock_irqrestore(&adapter->cmd_pending_q_lock, flags);

	return !is_cmd_pend_q_empty;
}

/*
 * This function returns the correct private structure pointer based
 * upon the BSS number.
 */
struct mwifiex_private *
mwifiex_bss_index_to_priv(struct mwifiex_adapter *adapter, u8 bss_index)
{
	if (!adapter || (bss_index >= adapter->priv_num))
		return NULL;
	return adapter->priv[bss_index];
}

/*
 * This is the main work queue function.
 *
 * It handles the main process, which in turn handles the complete
 * driver operations.
 */
static void mwifiex_main_work_queue(struct work_struct *work)
{
	struct mwifiex_adapter *adapter =
		container_of(work, struct mwifiex_adapter, main_work);

	if (adapter->surprise_removed)
		return;
	mwifiex_main_process(adapter);
}

/*
 * This function cancels all works in the queue and destroys
 * the main workqueue.
 */
static void
mwifiex_terminate_workqueue(struct mwifiex_adapter *adapter)
{
	flush_workqueue(adapter->workqueue);
	destroy_workqueue(adapter->workqueue);
	adapter->workqueue = NULL;
}

/*
 * This function adds the card.
 *
 * This function follows the following major steps to set up the device -
 *      - Initialize software. This includes probing the card, registering
 *        the interface operations table, and allocating/initializing the
 *        adapter structure
 *      - Set up the netlink socket
 *      - Create and start the main work queue
 *      - Register the device
 *      - Initialize firmware and hardware
 *      - Add logical interfaces
 */
int
mwifiex_add_card(void *card, struct semaphore *sem,
		 struct mwifiex_if_ops *if_ops, u8 iface_type)
{
	struct mwifiex_adapter *adapter;
	char fmt[64];
	struct mwifiex_private *priv;

	if (down_interruptible(sem))
		goto exit_sem_err;

	if (mwifiex_register(card, if_ops, (void **)&adapter)) {
		pr_err("%s: software init failed\n", __func__);
		goto err_init_sw;
	}

	adapter->iface_type = iface_type;

	adapter->hw_status = MWIFIEX_HW_STATUS_INITIALIZING;
	adapter->surprise_removed = false;
	init_waitqueue_head(&adapter->init_wait_q);
	adapter->is_suspended = false;
	adapter->hs_activated = false;
	init_waitqueue_head(&adapter->hs_activate_wait_q);
	adapter->cmd_wait_q_required = false;
	init_waitqueue_head(&adapter->cmd_wait_q.wait);
	adapter->cmd_wait_q.status = 0;
	adapter->scan_wait_q_woken = false;

	adapter->workqueue = create_workqueue("MWIFIEX_WORK_QUEUE");
	if (!adapter->workqueue)
		goto err_kmalloc;

	INIT_WORK(&adapter->main_work, mwifiex_main_work_queue);

	/* Register the device. Fill up the private data structure with relevant
	   information from the card and request for the required IRQ. */
	if (adapter->if_ops.register_dev(adapter)) {
		pr_err("%s: failed to register mwifiex device\n", __func__);
		goto err_registerdev;
	}

	if (mwifiex_init_hw_fw(adapter)) {
		pr_err("%s: firmware init failed\n", __func__);
		goto err_init_fw;
	}

	priv = adapter->priv[0];

	if (mwifiex_register_cfg80211(priv) != 0) {
		dev_err(adapter->dev, "cannot register netdevice"
			       " with cfg80211\n");
			goto err_init_fw;
	}

	rtnl_lock();
	/* Create station interface by default */
	if (!mwifiex_add_virtual_intf(priv->wdev->wiphy, "mlan%d",
				NL80211_IFTYPE_STATION, NULL, NULL)) {
		rtnl_unlock();
		dev_err(adapter->dev, "cannot create default station"
				" interface\n");
		goto err_add_intf;
	}

	rtnl_unlock();

	up(sem);

	mwifiex_drv_get_driver_version(adapter, fmt, sizeof(fmt) - 1);
	dev_notice(adapter->dev, "driver_version = %s\n", fmt);

	return 0;

err_add_intf:
	rtnl_lock();
	mwifiex_del_virtual_intf(priv->wdev->wiphy, priv->netdev);
	rtnl_unlock();
err_init_fw:
	pr_debug("info: %s: unregister device\n", __func__);
	adapter->if_ops.unregister_dev(adapter);
err_registerdev:
	adapter->surprise_removed = true;
	mwifiex_terminate_workqueue(adapter);
err_kmalloc:
	if ((adapter->hw_status == MWIFIEX_HW_STATUS_FW_READY) ||
	    (adapter->hw_status == MWIFIEX_HW_STATUS_READY)) {
		pr_debug("info: %s: shutdown mwifiex\n", __func__);
		adapter->init_wait_q_woken = false;

		if (mwifiex_shutdown_drv(adapter) == -EINPROGRESS)
			wait_event_interruptible(adapter->init_wait_q,
						 adapter->init_wait_q_woken);
	}

	mwifiex_free_adapter(adapter);

err_init_sw:
	up(sem);

exit_sem_err:
	return -1;
}
EXPORT_SYMBOL_GPL(mwifiex_add_card);

/*
 * This function removes the card.
 *
 * This function follows the following major steps to remove the device -
 *      - Stop data traffic
 *      - Shutdown firmware
 *      - Remove the logical interfaces
 *      - Terminate the work queue
 *      - Unregister the device
 *      - Free the adapter structure
 */
int mwifiex_remove_card(struct mwifiex_adapter *adapter, struct semaphore *sem)
{
	struct mwifiex_private *priv = NULL;
	int i;

	if (down_interruptible(sem))
		goto exit_sem_err;

	if (!adapter)
		goto exit_remove;

	adapter->surprise_removed = true;

	/* Stop data */
	for (i = 0; i < adapter->priv_num; i++) {
		priv = adapter->priv[i];
		if (priv && priv->netdev) {
			if (!netif_queue_stopped(priv->netdev))
				mwifiex_stop_net_dev_queue(priv->netdev,
								adapter);
			if (netif_carrier_ok(priv->netdev))
				netif_carrier_off(priv->netdev);
		}
	}

	dev_dbg(adapter->dev, "cmd: calling mwifiex_shutdown_drv...\n");
	adapter->init_wait_q_woken = false;

	if (mwifiex_shutdown_drv(adapter) == -EINPROGRESS)
		wait_event_interruptible(adapter->init_wait_q,
					 adapter->init_wait_q_woken);
	dev_dbg(adapter->dev, "cmd: mwifiex_shutdown_drv done\n");
	if (atomic_read(&adapter->rx_pending) ||
	    atomic_read(&adapter->tx_pending) ||
	    atomic_read(&adapter->cmd_pending)) {
		dev_err(adapter->dev, "rx_pending=%d, tx_pending=%d, "
		       "cmd_pending=%d\n",
		       atomic_read(&adapter->rx_pending),
		       atomic_read(&adapter->tx_pending),
		       atomic_read(&adapter->cmd_pending));
	}

	for (i = 0; i < adapter->priv_num; i++) {
		priv = adapter->priv[i];

		if (!priv)
			continue;

		rtnl_lock();
		mwifiex_del_virtual_intf(priv->wdev->wiphy, priv->netdev);
		rtnl_unlock();
	}

	priv = adapter->priv[0];
	if (!priv)
		goto exit_remove;

	wiphy_unregister(priv->wdev->wiphy);
	wiphy_free(priv->wdev->wiphy);
	kfree(priv->wdev);

	mwifiex_terminate_workqueue(adapter);

	/* Unregister device */
	dev_dbg(adapter->dev, "info: unregister device\n");
	adapter->if_ops.unregister_dev(adapter);
	/* Free adapter structure */
	dev_dbg(adapter->dev, "info: free adapter\n");
	mwifiex_free_adapter(adapter);

exit_remove:
	up(sem);
exit_sem_err:
	return 0;
}
EXPORT_SYMBOL_GPL(mwifiex_remove_card);

/*
 * This function initializes the module.
 *
 * The debug FS is also initialized if configured.
 */
static int
mwifiex_init_module(void)
{
#ifdef CONFIG_DEBUG_FS
	mwifiex_debugfs_init();
#endif
	return 0;
}

/*
 * This function cleans up the module.
 *
 * The debug FS is removed if available.
 */
static void
mwifiex_cleanup_module(void)
{
#ifdef CONFIG_DEBUG_FS
	mwifiex_debugfs_remove();
#endif
}

module_init(mwifiex_init_module);
module_exit(mwifiex_cleanup_module);

MODULE_AUTHOR("Marvell International Ltd.");
MODULE_DESCRIPTION("Marvell WiFi-Ex Driver version " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL v2");