/******************************************************************************
 *
 * Copyright(c) 2003 - 2011 Intel Corporation. All rights reserved.
 *
 * Portions of this file are derived from the ipw3945 project, as well
 * as portions of the ieee80211 subsystem header files.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
 *
 * The full GNU General Public License is included in this distribution in the
 * file called LICENSE.
 *
 * Contact Information:
 *  Intel Linux Wireless <ilw@linux.intel.com>
 * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
 *
 *****************************************************************************/
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/gfp.h>

#include "iwl-dev.h"
#include "iwl-agn.h"
#include "iwl-core.h"
#include "iwl-io.h"
#include "iwl-helpers.h"
#include "iwl-trans-int-pcie.h"

/******************************************************************************
 *
 * RX path functions
 *
 ******************************************************************************/

/*
 * Rx theory of operation
 *
 * Driver allocates a circular buffer of Receive Buffer Descriptors (RBDs),
 * each of which point to Receive Buffers to be filled by the NIC.  These get
 * used not only for Rx frames, but for any command response or notification
 * from the NIC.  The driver and NIC manage the Rx buffers by means
 * of indexes into the circular buffer.
 *
 * Rx Queue Indexes
 * The host/firmware share two index registers for managing the Rx buffers.
 *
 * The READ index maps to the first position that the firmware may be writing
 * to -- the driver can read up to (but not including) this position and get
 * good data.
 * The READ index is managed by the firmware once the card is enabled.
 *
 * The WRITE index maps to the last position the driver has read from -- the
 * position preceding WRITE is the last slot the firmware can place a packet.
 *
 * The queue is empty (no good data) if WRITE = READ - 1, and is full if
 * WRITE = READ.
 *
 * During initialization, the host sets up the READ queue position to the first
 * INDEX position, and WRITE to the last (READ - 1 wrapped)
 *
 * When the firmware places a packet in a buffer, it will advance the READ index
 * and fire the RX interrupt.  The driver can then query the READ index and
 * process as many packets as possible, moving the WRITE index forward as it
 * resets the Rx queue buffers with new memory.
 *
 * The management in the driver is as follows:
 * + A list of pre-allocated SKBs is stored in iwl->rxq->rx_free.  When
 *   iwl->rxq->free_count drops to or below RX_LOW_WATERMARK, work is scheduled
 *   to replenish the iwl->rxq->rx_free.
 * + In iwl_rx_replenish (scheduled) if 'processed' != 'read' then the
 *   iwl->rxq is replenished and the READ INDEX is updated (updating the
 *   'processed' and 'read' driver indexes as well)
 * + A received packet is processed and handed to the kernel network stack,
 *   detached from the iwl->rxq.  The driver 'processed' index is updated.
 * + The Host/Firmware iwl->rxq is replenished at tasklet time from the rx_free
 *   list. If there are no allocated buffers in iwl->rxq->rx_free, the READ
 *   INDEX is not incremented and iwl->status(RX_STALLED) is set.  If there
 *   were enough free buffers and RX_STALLED is set it is cleared.
 *
 *
 * Driver sequence:
 *
 * iwl_rx_queue_alloc()   Allocates rx_free
 * iwl_rx_replenish()     Replenishes rx_free list from rx_used, and calls
 *                            iwl_rx_queue_restock
 * iwl_rx_queue_restock() Moves available buffers from rx_free into Rx
 *                            queue, updates firmware pointers, and updates
 *                            the WRITE index.  If insufficient rx_free buffers
 *                            are available, schedules iwl_rx_replenish
 *
 * -- enable interrupts --
 * ISR - iwl_rx()         Detach iwl_rx_mem_buffers from pool up to the
 *                            READ INDEX, detaching the SKB from the pool.
 *                            Moves the packet buffer from queue to rx_used.
 *                            Calls iwl_rx_queue_restock to refill any empty
 *                            slots.
 * ...
 *
 */

/**
 * iwl_rx_queue_space - Return number of free slots available in queue.
 */
static int iwl_rx_queue_space(const struct iwl_rx_queue *q)
{
	int s = q->read - q->write;
	if (s <= 0)
		s += RX_QUEUE_SIZE;
	/* keep some buffer to not confuse full and empty queue */
	s -= 2;
	if (s < 0)
		s = 0;
	return s;
}

/**
 * iwl_rx_queue_update_write_ptr - Update the write pointer for the RX queue
 */
void iwl_rx_queue_update_write_ptr(struct iwl_priv *priv,
			struct iwl_rx_queue *q)
{
	unsigned long flags;
	u32 reg;

	spin_lock_irqsave(&q->lock, flags);

	if (q->need_update == 0)
		goto exit_unlock;

	if (priv->cfg->base_params->shadow_reg_enable) {
		/* shadow register enabled */
		/* Device expects a multiple of 8 */
		q->write_actual = (q->write & ~0x7);
		iwl_write32(priv, FH_RSCSR_CHNL0_WPTR, q->write_actual);
	} else {
		/* If power-saving is in use, make sure device is awake */
		if (test_bit(STATUS_POWER_PMI, &priv->status)) {
			reg = iwl_read32(priv, CSR_UCODE_DRV_GP1);

			if (reg & CSR_UCODE_DRV_GP1_BIT_MAC_SLEEP) {
				IWL_DEBUG_INFO(priv,
					"Rx queue requesting wakeup,"
					" GP1 = 0x%x\n", reg);
				iwl_set_bit(priv, CSR_GP_CNTRL,
					CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);
				goto exit_unlock;
			}

			q->write_actual = (q->write & ~0x7);
			iwl_write_direct32(priv, FH_RSCSR_CHNL0_WPTR,
					q->write_actual);

		/* Else device is assumed to be awake */
		} else {
			/* Device expects a multiple of 8 */
			q->write_actual = (q->write & ~0x7);
			iwl_write_direct32(priv, FH_RSCSR_CHNL0_WPTR,
				q->write_actual);
		}
	}
	q->need_update = 0;

 exit_unlock:
	spin_unlock_irqrestore(&q->lock, flags);
}

/**
 * iwlagn_dma_addr2rbd_ptr - convert a DMA address to a uCode read buffer ptr
 */
static inline __le32 iwlagn_dma_addr2rbd_ptr(struct iwl_priv *priv,
					  dma_addr_t dma_addr)
{
	return cpu_to_le32((u32)(dma_addr >> 8));
}

/**
 * iwlagn_rx_queue_restock - refill RX queue from pre-allocated pool
 *
 * If there are slots in the RX queue that need to be restocked,
 * and we have free pre-allocated buffers, fill the ranks as much
 * as we can, pulling from rx_free.
 *
 * This moves the 'write' index forward to catch up with 'processed', and
 * also updates the memory address in the firmware to reference the new
 * target buffer.
 */
static void iwlagn_rx_queue_restock(struct iwl_priv *priv)
{
	struct iwl_rx_queue *rxq = &priv->rxq;
	struct list_head *element;
	struct iwl_rx_mem_buffer *rxb;
	unsigned long flags;

	spin_lock_irqsave(&rxq->lock, flags);
	while ((iwl_rx_queue_space(rxq) > 0) && (rxq->free_count)) {
		/* The overwritten rxb must be a used one */
		rxb = rxq->queue[rxq->write];
		BUG_ON(rxb && rxb->page);

		/* Get next free Rx buffer, remove from free list */
		element = rxq->rx_free.next;
		rxb = list_entry(element, struct iwl_rx_mem_buffer, list);
		list_del(element);

		/* Point to Rx buffer via next RBD in circular buffer */
		rxq->bd[rxq->write] = iwlagn_dma_addr2rbd_ptr(priv,
							      rxb->page_dma);
		rxq->queue[rxq->write] = rxb;
		rxq->write = (rxq->write + 1) & RX_QUEUE_MASK;
		rxq->free_count--;
	}
	spin_unlock_irqrestore(&rxq->lock, flags);
	/* If the pre-allocated buffer pool is dropping low, schedule to
	 * refill it */
	if (rxq->free_count <= RX_LOW_WATERMARK)
		queue_work(priv->workqueue, &priv->rx_replenish);


	/* If we've added more space for the firmware to place data, tell it.
	 * Increment device's write pointer in multiples of 8. */
	if (rxq->write_actual != (rxq->write & ~0x7)) {
		spin_lock_irqsave(&rxq->lock, flags);
		rxq->need_update = 1;
		spin_unlock_irqrestore(&rxq->lock, flags);
		iwl_rx_queue_update_write_ptr(priv, rxq);
	}
}

/**
 * iwlagn_rx_replenish - Move all used packet from rx_used to rx_free
 *
 * When moving to rx_free an SKB is allocated for the slot.
 *
 * Also restock the Rx queue via iwl_rx_queue_restock.
 * This is called as a scheduled work item (except for during initialization)
 */
static void iwlagn_rx_allocate(struct iwl_priv *priv, gfp_t priority)
{
	struct iwl_rx_queue *rxq = &priv->rxq;
	struct list_head *element;
	struct iwl_rx_mem_buffer *rxb;
	struct page *page;
	unsigned long flags;
	gfp_t gfp_mask = priority;

	while (1) {
		spin_lock_irqsave(&rxq->lock, flags);
		if (list_empty(&rxq->rx_used)) {
			spin_unlock_irqrestore(&rxq->lock, flags);
			return;
		}
		spin_unlock_irqrestore(&rxq->lock, flags);

		if (rxq->free_count > RX_LOW_WATERMARK)
			gfp_mask |= __GFP_NOWARN;

		if (priv->hw_params.rx_page_order > 0)
			gfp_mask |= __GFP_COMP;

		/* Alloc a new receive buffer */
		page = alloc_pages(gfp_mask, priv->hw_params.rx_page_order);
		if (!page) {
			if (net_ratelimit())
				IWL_DEBUG_INFO(priv, "alloc_pages failed, "
					       "order: %d\n",
					       priv->hw_params.rx_page_order);

			if ((rxq->free_count <= RX_LOW_WATERMARK) &&
			    net_ratelimit())
				IWL_CRIT(priv, "Failed to alloc_pages with %s."
					 "Only %u free buffers remaining.\n",
					 priority == GFP_ATOMIC ?
					 "GFP_ATOMIC" : "GFP_KERNEL",
					 rxq->free_count);
			/* We don't reschedule replenish work here -- we will
			 * call the restock method and if it still needs
			 * more buffers it will schedule replenish */
			return;
		}

		spin_lock_irqsave(&rxq->lock, flags);

		if (list_empty(&rxq->rx_used)) {
			spin_unlock_irqrestore(&rxq->lock, flags);
			__free_pages(page, priv->hw_params.rx_page_order);
			return;
		}
		element = rxq->rx_used.next;
		rxb = list_entry(element, struct iwl_rx_mem_buffer, list);
		list_del(element);

		spin_unlock_irqrestore(&rxq->lock, flags);

		BUG_ON(rxb->page);
		rxb->page = page;
		/* Get physical address of the RB */
		rxb->page_dma = dma_map_page(priv->bus->dev, page, 0,
				PAGE_SIZE << priv->hw_params.rx_page_order,
				DMA_FROM_DEVICE);
		/* dma address must be no more than 36 bits */
		BUG_ON(rxb->page_dma & ~DMA_BIT_MASK(36));
		/* and also 256 byte aligned! */
		BUG_ON(rxb->page_dma & DMA_BIT_MASK(8));

		spin_lock_irqsave(&rxq->lock, flags);

		list_add_tail(&rxb->list, &rxq->rx_free);
		rxq->free_count++;

		spin_unlock_irqrestore(&rxq->lock, flags);
	}
}

void iwlagn_rx_replenish(struct iwl_priv *priv)
{
	unsigned long flags;

	iwlagn_rx_allocate(priv, GFP_KERNEL);

	spin_lock_irqsave(&priv->lock, flags);
	iwlagn_rx_queue_restock(priv);
	spin_unlock_irqrestore(&priv->lock, flags);
}

static void iwlagn_rx_replenish_now(struct iwl_priv *priv)
{
	iwlagn_rx_allocate(priv, GFP_ATOMIC);

	iwlagn_rx_queue_restock(priv);
}

void iwl_bg_rx_replenish(struct work_struct *data)
{
	struct iwl_priv *priv =
	    container_of(data, struct iwl_priv, rx_replenish);

	if (test_bit(STATUS_EXIT_PENDING, &priv->status))
		return;

	mutex_lock(&priv->mutex);
	iwlagn_rx_replenish(priv);
	mutex_unlock(&priv->mutex);
}

/**
 * iwl_rx_handle - Main entry function for receiving responses from uCode
 *
 * Uses the priv->rx_handlers callback function array to invoke
 * the appropriate handlers, including command responses,
 * frame-received notifications, and other notifications.
 */
static void iwl_rx_handle(struct iwl_priv *priv)
{
	struct iwl_rx_mem_buffer *rxb;
	struct iwl_rx_packet *pkt;
	struct iwl_rx_queue *rxq = &priv->rxq;
	u32 r, i;
	int reclaim;
	unsigned long flags;
	u8 fill_rx = 0;
	u32 count = 8;
	int total_empty;

	/* uCode's read index (stored in shared DRAM) indicates the last Rx
	 * buffer that the driver may process (last buffer filled by ucode). */
	r = le16_to_cpu(rxq->rb_stts->closed_rb_num) &  0x0FFF;
	i = rxq->read;

	/* Rx interrupt, but nothing sent from uCode */
	if (i == r)
		IWL_DEBUG_RX(priv, "r = %d, i = %d\n", r, i);

	/* calculate total frames need to be restock after handling RX */
	total_empty = r - rxq->write_actual;
	if (total_empty < 0)
		total_empty += RX_QUEUE_SIZE;

	if (total_empty > (RX_QUEUE_SIZE / 2))
		fill_rx = 1;

	while (i != r) {
		int len;

		rxb = rxq->queue[i];

		/* If an RXB doesn't have a Rx queue slot associated with it,
		 * then a bug has been introduced in the queue refilling
		 * routines -- catch it here */
		if (WARN_ON(rxb == NULL)) {
			i = (i + 1) & RX_QUEUE_MASK;
			continue;
		}

		rxq->queue[i] = NULL;

		dma_unmap_page(priv->bus->dev, rxb->page_dma,
			       PAGE_SIZE << priv->hw_params.rx_page_order,
			       DMA_FROM_DEVICE);
		pkt = rxb_addr(rxb);

		IWL_DEBUG_RX(priv, "r = %d, i = %d, %s, 0x%02x\n", r,
			i, get_cmd_string(pkt->hdr.cmd), pkt->hdr.cmd);

		len = le32_to_cpu(pkt->len_n_flags) & FH_RSCSR_FRAME_SIZE_MSK;
		len += sizeof(u32); /* account for status word */
		trace_iwlwifi_dev_rx(priv, pkt, len);

		/* Reclaim a command buffer only if this packet is a response
		 *   to a (driver-originated) command.
		 * If the packet (e.g. Rx frame) originated from uCode,
		 *   there is no command buffer to reclaim.
		 * Ucode should set SEQ_RX_FRAME bit if ucode-originated,
		 *   but apparently a few don't get set; catch them here. */
		reclaim = !(pkt->hdr.sequence & SEQ_RX_FRAME) &&
			(pkt->hdr.cmd != REPLY_RX_PHY_CMD) &&
			(pkt->hdr.cmd != REPLY_RX) &&
			(pkt->hdr.cmd != REPLY_RX_MPDU_CMD) &&
			(pkt->hdr.cmd != REPLY_COMPRESSED_BA) &&
			(pkt->hdr.cmd != STATISTICS_NOTIFICATION) &&
			(pkt->hdr.cmd != REPLY_TX);

		iwl_rx_dispatch(priv, rxb);

		/*
		 * XXX: After here, we should always check rxb->page
		 * against NULL before touching it or its virtual
		 * memory (pkt). Because some rx_handler might have
		 * already taken or freed the pages.
		 */

		if (reclaim) {
			/* Invoke any callbacks, transfer the buffer to caller,
			 * and fire off the (possibly) blocking
			 * trans_send_cmd()
			 * as we reclaim the driver command queue */
			if (rxb->page)
				iwl_tx_cmd_complete(priv, rxb);
			else
				IWL_WARN(priv, "Claim null rxb?\n");
		}

		/* Reuse the page if possible. For notification packets and
		 * SKBs that fail to Rx correctly, add them back into the
		 * rx_free list for reuse later. */
		spin_lock_irqsave(&rxq->lock, flags);
		if (rxb->page != NULL) {
			rxb->page_dma = dma_map_page(priv->bus->dev, rxb->page,
				0, PAGE_SIZE << priv->hw_params.rx_page_order,
				DMA_FROM_DEVICE);
			list_add_tail(&rxb->list, &rxq->rx_free);
			rxq->free_count++;
		} else
			list_add_tail(&rxb->list, &rxq->rx_used);

		spin_unlock_irqrestore(&rxq->lock, flags);

		i = (i + 1) & RX_QUEUE_MASK;
		/* If there are a lot of unused frames,
		 * restock the Rx queue so ucode wont assert. */
		if (fill_rx) {
			count++;
			if (count >= 8) {
				rxq->read = i;
				iwlagn_rx_replenish_now(priv);
				count = 0;
			}
		}
	}

	/* Backtrack one entry */
	rxq->read = i;
	if (fill_rx)
		iwlagn_rx_replenish_now(priv);
	else
		iwlagn_rx_queue_restock(priv);
}

/* tasklet for iwlagn interrupt */
void iwl_irq_tasklet(struct iwl_priv *priv)
{
	u32 inta = 0;
	u32 handled = 0;
	unsigned long flags;
	u32 i;
#ifdef CONFIG_IWLWIFI_DEBUG
	u32 inta_mask;
#endif

	spin_lock_irqsave(&priv->lock, flags);

	/* Ack/clear/reset pending uCode interrupts.
	 * Note:  Some bits in CSR_INT are "OR" of bits in CSR_FH_INT_STATUS,
	 */
	/* There is a hardware bug in the interrupt mask function that some
	 * interrupts (i.e. CSR_INT_BIT_SCD) can still be generated even if
	 * they are disabled in the CSR_INT_MASK register. Furthermore the
	 * ICT interrupt handling mechanism has another bug that might cause
	 * these unmasked interrupts fail to be detected. We workaround the
	 * hardware bugs here by ACKing all the possible interrupts so that
	 * interrupt coalescing can still be achieved.
	 */
	iwl_write32(priv, CSR_INT, priv->inta | ~priv->inta_mask);

	inta = priv->inta;

#ifdef CONFIG_IWLWIFI_DEBUG
	if (iwl_get_debug_level(priv) & IWL_DL_ISR) {
		/* just for debug */
		inta_mask = iwl_read32(priv, CSR_INT_MASK);
		IWL_DEBUG_ISR(priv, "inta 0x%08x, enabled 0x%08x\n ",
				inta, inta_mask);
	}
#endif

	spin_unlock_irqrestore(&priv->lock, flags);

	/* saved interrupt in inta variable now we can reset priv->inta */
	priv->inta = 0;

	/* Now service all interrupt bits discovered above. */
	if (inta & CSR_INT_BIT_HW_ERR) {
		IWL_ERR(priv, "Hardware error detected.  Restarting.\n");

		/* Tell the device to stop sending interrupts */
		iwl_disable_interrupts(priv);

		priv->isr_stats.hw++;
		iwl_irq_handle_error(priv);

		handled |= CSR_INT_BIT_HW_ERR;

		return;
	}

#ifdef CONFIG_IWLWIFI_DEBUG
	if (iwl_get_debug_level(priv) & (IWL_DL_ISR)) {
		/* NIC fires this, but we don't use it, redundant with WAKEUP */
		if (inta & CSR_INT_BIT_SCD) {
			IWL_DEBUG_ISR(priv, "Scheduler finished to transmit "
				      "the frame/frames.\n");
			priv->isr_stats.sch++;
		}

		/* Alive notification via Rx interrupt will do the real work */
		if (inta & CSR_INT_BIT_ALIVE) {
			IWL_DEBUG_ISR(priv, "Alive interrupt\n");
			priv->isr_stats.alive++;
		}
	}
#endif
	/* Safely ignore these bits for debug checks below */
	inta &= ~(CSR_INT_BIT_SCD | CSR_INT_BIT_ALIVE);

	/* HW RF KILL switch toggled */
	if (inta & CSR_INT_BIT_RF_KILL) {
		int hw_rf_kill = 0;
		if (!(iwl_read32(priv, CSR_GP_CNTRL) &
				CSR_GP_CNTRL_REG_FLAG_HW_RF_KILL_SW))
			hw_rf_kill = 1;

		IWL_WARN(priv, "RF_KILL bit toggled to %s.\n",
				hw_rf_kill ? "disable radio" : "enable radio");

		priv->isr_stats.rfkill++;

		/* driver only loads ucode once setting the interface up.
		 * the driver allows loading the ucode even if the radio
		 * is killed. Hence update the killswitch state here. The
		 * rfkill handler will care about restarting if needed.
		 */
		if (!test_bit(STATUS_ALIVE, &priv->status)) {
			if (hw_rf_kill)
				set_bit(STATUS_RF_KILL_HW, &priv->status);
			else
				clear_bit(STATUS_RF_KILL_HW, &priv->status);
			wiphy_rfkill_set_hw_state(priv->hw->wiphy, hw_rf_kill);
		}

		handled |= CSR_INT_BIT_RF_KILL;
	}

	/* Chip got too hot and stopped itself */
	if (inta & CSR_INT_BIT_CT_KILL) {
		IWL_ERR(priv, "Microcode CT kill error detected.\n");
		priv->isr_stats.ctkill++;
		handled |= CSR_INT_BIT_CT_KILL;
	}

	/* Error detected by uCode */
	if (inta & CSR_INT_BIT_SW_ERR) {
		IWL_ERR(priv, "Microcode SW error detected. "
			" Restarting 0x%X.\n", inta);
		priv->isr_stats.sw++;
		iwl_irq_handle_error(priv);
		handled |= CSR_INT_BIT_SW_ERR;
	}

	/* uCode wakes up after power-down sleep */
	if (inta & CSR_INT_BIT_WAKEUP) {
		IWL_DEBUG_ISR(priv, "Wakeup interrupt\n");
		iwl_rx_queue_update_write_ptr(priv, &priv->rxq);
		for (i = 0; i < priv->hw_params.max_txq_num; i++)
			iwl_txq_update_write_ptr(priv, &priv->txq[i]);

		priv->isr_stats.wakeup++;

		handled |= CSR_INT_BIT_WAKEUP;
	}

	/* All uCode command responses, including Tx command responses,
	 * Rx "responses" (frame-received notification), and other
	 * notifications from uCode come through here*/
	if (inta & (CSR_INT_BIT_FH_RX | CSR_INT_BIT_SW_RX |
			CSR_INT_BIT_RX_PERIODIC)) {
		IWL_DEBUG_ISR(priv, "Rx interrupt\n");
		if (inta & (CSR_INT_BIT_FH_RX | CSR_INT_BIT_SW_RX)) {
			handled |= (CSR_INT_BIT_FH_RX | CSR_INT_BIT_SW_RX);
			iwl_write32(priv, CSR_FH_INT_STATUS,
					CSR_FH_INT_RX_MASK);
		}
		if (inta & CSR_INT_BIT_RX_PERIODIC) {
			handled |= CSR_INT_BIT_RX_PERIODIC;
			iwl_write32(priv, CSR_INT, CSR_INT_BIT_RX_PERIODIC);
		}
		/* Sending RX interrupt require many steps to be done in the
		 * the device:
		 * 1- write interrupt to current index in ICT table.
		 * 2- dma RX frame.
		 * 3- update RX shared data to indicate last write index.
		 * 4- send interrupt.
		 * This could lead to RX race, driver could receive RX interrupt
		 * but the shared data changes does not reflect this;
		 * periodic interrupt will detect any dangling Rx activity.
		 */

		/* Disable periodic interrupt; we use it as just a one-shot. */
		iwl_write8(priv, CSR_INT_PERIODIC_REG,
			    CSR_INT_PERIODIC_DIS);
		iwl_rx_handle(priv);

		/*
		 * Enable periodic interrupt in 8 msec only if we received
		 * real RX interrupt (instead of just periodic int), to catch
		 * any dangling Rx interrupt.  If it was just the periodic
		 * interrupt, there was no dangling Rx activity, and no need
		 * to extend the periodic interrupt; one-shot is enough.
		 */
		if (inta & (CSR_INT_BIT_FH_RX | CSR_INT_BIT_SW_RX))
			iwl_write8(priv, CSR_INT_PERIODIC_REG,
				    CSR_INT_PERIODIC_ENA);

		priv->isr_stats.rx++;
	}

	/* This "Tx" DMA channel is used only for loading uCode */
	if (inta & CSR_INT_BIT_FH_TX) {
		iwl_write32(priv, CSR_FH_INT_STATUS, CSR_FH_INT_TX_MASK);
		IWL_DEBUG_ISR(priv, "uCode load interrupt\n");
		priv->isr_stats.tx++;
		handled |= CSR_INT_BIT_FH_TX;
		/* Wake up uCode load routine, now that load is complete */
		priv->ucode_write_complete = 1;
		wake_up_interruptible(&priv->wait_command_queue);
	}

	if (inta & ~handled) {
		IWL_ERR(priv, "Unhandled INTA bits 0x%08x\n", inta & ~handled);
		priv->isr_stats.unhandled++;
	}

	if (inta & ~(priv->inta_mask)) {
		IWL_WARN(priv, "Disabled INTA bits 0x%08x were pending\n",
			 inta & ~priv->inta_mask);
	}

	/* Re-enable all interrupts */
	/* only Re-enable if disabled by irq */
	if (test_bit(STATUS_INT_ENABLED, &priv->status))
		iwl_enable_interrupts(priv);
	/* Re-enable RF_KILL if it occurred */
	else if (handled & CSR_INT_BIT_RF_KILL)
		iwl_enable_rfkill_int(priv);
}

/******************************************************************************
 *
 * ICT functions
 *
 ******************************************************************************/
#define ICT_COUNT (PAGE_SIZE/sizeof(u32))

/* Free dram table */
void iwl_free_isr_ict(struct iwl_priv *priv)
{
	if (priv->ict_tbl_vir) {
		dma_free_coherent(priv->bus->dev,
				  (sizeof(u32) * ICT_COUNT) + PAGE_SIZE,
				  priv->ict_tbl_vir,
				  priv->ict_tbl_dma);
		priv->ict_tbl_vir = NULL;
		memset(&priv->ict_tbl_dma, 0,
			sizeof(priv->ict_tbl_dma));
		memset(&priv->aligned_ict_tbl_dma, 0,
			sizeof(priv->aligned_ict_tbl_dma));
	}
}


/* allocate dram shared table it is a PAGE_SIZE aligned
 * also reset all data related to ICT table interrupt.
 */
int iwl_alloc_isr_ict(struct iwl_priv *priv)
{

	/* allocate shrared data table */
	priv->ict_tbl_vir =
		dma_alloc_coherent(priv->bus->dev,
				   (sizeof(u32) * ICT_COUNT) + PAGE_SIZE,
				   &priv->ict_tbl_dma, GFP_KERNEL);
	if (!priv->ict_tbl_vir)
		return -ENOMEM;

	/* align table to PAGE_SIZE boundary */
	priv->aligned_ict_tbl_dma =
		ALIGN(priv->ict_tbl_dma, PAGE_SIZE);

	IWL_DEBUG_ISR(priv, "ict dma addr %Lx dma aligned %Lx diff %d\n",
			     (unsigned long long)priv->ict_tbl_dma,
			     (unsigned long long)priv->aligned_ict_tbl_dma,
			     (int)(priv->aligned_ict_tbl_dma -
			     priv->ict_tbl_dma));

	priv->ict_tbl =  priv->ict_tbl_vir +
			  (priv->aligned_ict_tbl_dma -
			  priv->ict_tbl_dma);

	IWL_DEBUG_ISR(priv, "ict vir addr %p vir aligned %p diff %d\n",
			     priv->ict_tbl, priv->ict_tbl_vir,
			(int)(priv->aligned_ict_tbl_dma -
			    priv->ict_tbl_dma));

	/* reset table and index to all 0 */
	memset(priv->ict_tbl_vir, 0,
		(sizeof(u32) * ICT_COUNT) + PAGE_SIZE);
	priv->ict_index = 0;

	/* add periodic RX interrupt */
	priv->inta_mask |= CSR_INT_BIT_RX_PERIODIC;
	return 0;
}

/* Device is going up inform it about using ICT interrupt table,
 * also we need to tell the driver to start using ICT interrupt.
 */
int iwl_reset_ict(struct iwl_priv *priv)
{
	u32 val;
	unsigned long flags;

	if (!priv->ict_tbl_vir)
		return 0;

	spin_lock_irqsave(&priv->lock, flags);
	iwl_disable_interrupts(priv);

	memset(&priv->ict_tbl[0], 0, sizeof(u32) * ICT_COUNT);

	val = priv->aligned_ict_tbl_dma >> PAGE_SHIFT;

	val |= CSR_DRAM_INT_TBL_ENABLE;
	val |= CSR_DRAM_INIT_TBL_WRAP_CHECK;

	IWL_DEBUG_ISR(priv, "CSR_DRAM_INT_TBL_REG =0x%X "
			"aligned dma address %Lx\n",
			val,
			(unsigned long long)priv->aligned_ict_tbl_dma);

	iwl_write32(priv, CSR_DRAM_INT_TBL_REG, val);
	priv->use_ict = true;
	priv->ict_index = 0;
	iwl_write32(priv, CSR_INT, priv->inta_mask);
	iwl_enable_interrupts(priv);
	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;
}

/* Device is going down disable ict interrupt usage */
void iwl_disable_ict(struct iwl_priv *priv)
{
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);
	priv->use_ict = false;
	spin_unlock_irqrestore(&priv->lock, flags);
}

static irqreturn_t iwl_isr(int irq, void *data)
{
	struct iwl_priv *priv = data;
	u32 inta, inta_mask;
	unsigned long flags;
#ifdef CONFIG_IWLWIFI_DEBUG
	u32 inta_fh;
#endif
	if (!priv)
		return IRQ_NONE;

	spin_lock_irqsave(&priv->lock, flags);

	/* Disable (but don't clear!) interrupts here to avoid
	 *    back-to-back ISRs and sporadic interrupts from our NIC.
	 * If we have something to service, the tasklet will re-enable ints.
	 * If we *don't* have something, we'll re-enable before leaving here. */
	inta_mask = iwl_read32(priv, CSR_INT_MASK);  /* just for debug */
	iwl_write32(priv, CSR_INT_MASK, 0x00000000);

	/* Discover which interrupts are active/pending */
	inta = iwl_read32(priv, CSR_INT);

	/* Ignore interrupt if there's nothing in NIC to service.
	 * This may be due to IRQ shared with another device,
	 * or due to sporadic interrupts thrown from our NIC. */
	if (!inta) {
		IWL_DEBUG_ISR(priv, "Ignore interrupt, inta == 0\n");
		goto none;
	}

	if ((inta == 0xFFFFFFFF) || ((inta & 0xFFFFFFF0) == 0xa5a5a5a0)) {
		/* Hardware disappeared. It might have already raised
		 * an interrupt */
		IWL_WARN(priv, "HARDWARE GONE?? INTA == 0x%08x\n", inta);
		goto unplugged;
	}

#ifdef CONFIG_IWLWIFI_DEBUG
	if (iwl_get_debug_level(priv) & (IWL_DL_ISR)) {
		inta_fh = iwl_read32(priv, CSR_FH_INT_STATUS);
		IWL_DEBUG_ISR(priv, "ISR inta 0x%08x, enabled 0x%08x, "
			      "fh 0x%08x\n", inta, inta_mask, inta_fh);
	}
#endif

	priv->inta |= inta;
	/* iwl_irq_tasklet() will service interrupts and re-enable them */
	if (likely(inta))
		tasklet_schedule(&priv->irq_tasklet);
	else if (test_bit(STATUS_INT_ENABLED, &priv->status) &&
			!priv->inta)
		iwl_enable_interrupts(priv);

 unplugged:
	spin_unlock_irqrestore(&priv->lock, flags);
	return IRQ_HANDLED;

 none:
	/* re-enable interrupts here since we don't have anything to service. */
	/* only Re-enable if disabled by irq  and no schedules tasklet. */
	if (test_bit(STATUS_INT_ENABLED, &priv->status) && !priv->inta)
		iwl_enable_interrupts(priv);

	spin_unlock_irqrestore(&priv->lock, flags);
	return IRQ_NONE;
}

/* interrupt handler using ict table, with this interrupt driver will
 * stop using INTA register to get device's interrupt, reading this register
 * is expensive, device will write interrupts in ICT dram table, increment
 * index then will fire interrupt to driver, driver will OR all ICT table
 * entries from current index up to table entry with 0 value. the result is
 * the interrupt we need to service, driver will set the entries back to 0 and
 * set index.
 */
irqreturn_t iwl_isr_ict(int irq, void *data)
{
	struct iwl_priv *priv = data;
	u32 inta, inta_mask;
	u32 val = 0;
	unsigned long flags;

	if (!priv)
		return IRQ_NONE;

	/* dram interrupt table not set yet,
	 * use legacy interrupt.
	 */
	if (!priv->use_ict)
		return iwl_isr(irq, data);

	spin_lock_irqsave(&priv->lock, flags);

	/* Disable (but don't clear!) interrupts here to avoid
	 * back-to-back ISRs and sporadic interrupts from our NIC.
	 * If we have something to service, the tasklet will re-enable ints.
	 * If we *don't* have something, we'll re-enable before leaving here.
	 */
	inta_mask = iwl_read32(priv, CSR_INT_MASK);  /* just for debug */
	iwl_write32(priv, CSR_INT_MASK, 0x00000000);


	/* Ignore interrupt if there's nothing in NIC to service.
	 * This may be due to IRQ shared with another device,
	 * or due to sporadic interrupts thrown from our NIC. */
	if (!priv->ict_tbl[priv->ict_index]) {
		IWL_DEBUG_ISR(priv, "Ignore interrupt, inta == 0\n");
		goto none;
	}

	/* read all entries that not 0 start with ict_index */
	while (priv->ict_tbl[priv->ict_index]) {

		val |= le32_to_cpu(priv->ict_tbl[priv->ict_index]);
		IWL_DEBUG_ISR(priv, "ICT index %d value 0x%08X\n",
				priv->ict_index,
				le32_to_cpu(
				    priv->ict_tbl[priv->ict_index]));
		priv->ict_tbl[priv->ict_index] = 0;
		priv->ict_index = iwl_queue_inc_wrap(priv->ict_index,
						     ICT_COUNT);

	}

	/* We should not get this value, just ignore it. */
	if (val == 0xffffffff)
		val = 0;

	/*
	 * this is a w/a for a h/w bug. the h/w bug may cause the Rx bit
	 * (bit 15 before shifting it to 31) to clear when using interrupt
	 * coalescing. fortunately, bits 18 and 19 stay set when this happens
	 * so we use them to decide on the real state of the Rx bit.
	 * In order words, bit 15 is set if bit 18 or bit 19 are set.
	 */
	if (val & 0xC0000)
		val |= 0x8000;

	inta = (0xff & val) | ((0xff00 & val) << 16);
	IWL_DEBUG_ISR(priv, "ISR inta 0x%08x, enabled 0x%08x ict 0x%08x\n",
			inta, inta_mask, val);

	inta &= priv->inta_mask;
	priv->inta |= inta;

	/* iwl_irq_tasklet() will service interrupts and re-enable them */
	if (likely(inta))
		tasklet_schedule(&priv->irq_tasklet);
	else if (test_bit(STATUS_INT_ENABLED, &priv->status) &&
			!priv->inta) {
		/* Allow interrupt if was disabled by this handler and
		 * no tasklet was schedules, We should not enable interrupt,
		 * tasklet will enable it.
		 */
		iwl_enable_interrupts(priv);
	}

	spin_unlock_irqrestore(&priv->lock, flags);
	return IRQ_HANDLED;

 none:
	/* re-enable interrupts here since we don't have anything to service.
	 * only Re-enable if disabled by irq.
	 */
	if (test_bit(STATUS_INT_ENABLED, &priv->status) && !priv->inta)
		iwl_enable_interrupts(priv);

	spin_unlock_irqrestore(&priv->lock, flags);
	return IRQ_NONE;
}