/*
 * CDDL HEADER START
 *
 * Copyright(c) 2007-2008 Intel Corporation. All rights reserved.
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at:
 *	http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When using or redistributing this file, you may do so under the
 * License only. No other modification of this header is permitted.
 *
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms of the CDDL.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include "igb_sw.h"

/* function prototypes */
static mblk_t *igb_rx_bind(igb_rx_ring_t *, uint32_t, uint32_t);
static mblk_t *igb_rx_copy(igb_rx_ring_t *, uint32_t, uint32_t);
static void igb_rx_assoc_hcksum(mblk_t *, uint32_t);

#ifndef IGB_DEBUG
#pragma inline(igb_rx_assoc_hcksum)
#endif


/*
 * igb_rx_recycle - the call-back function to reclaim rx buffer
 *
 * This function is called when an mp is freed by the user thru
 * freeb call (Only for mp constructed through desballoc call).
 * It returns back the freed buffer to the free list.
 */
void
igb_rx_recycle(caddr_t arg)
{
	igb_rx_ring_t *rx_ring;
	rx_control_block_t *recycle_rcb;
	uint32_t free_index;

	recycle_rcb = (rx_control_block_t *)(uintptr_t)arg;
	rx_ring = recycle_rcb->rx_ring;

	if (recycle_rcb->state == RCB_FREE)
		return;

	recycle_rcb->state = RCB_FREE;

	ASSERT(recycle_rcb->mp == NULL);

	/*
	 * Using the recycled data buffer to generate a new mblk
	 */
	recycle_rcb->mp = desballoc((unsigned char *)
	    (recycle_rcb->rx_buf.address - IPHDR_ALIGN_ROOM),
	    (recycle_rcb->rx_buf.size + IPHDR_ALIGN_ROOM),
	    0, &recycle_rcb->free_rtn);
	if (recycle_rcb->mp != NULL) {
		recycle_rcb->mp->b_rptr += IPHDR_ALIGN_ROOM;
		recycle_rcb->mp->b_wptr += IPHDR_ALIGN_ROOM;
	}

	/*
	 * Put the recycled rx control block into free list
	 */
	mutex_enter(&rx_ring->recycle_lock);

	free_index = rx_ring->rcb_tail;
	ASSERT(rx_ring->free_list[free_index] == NULL);

	rx_ring->free_list[free_index] = recycle_rcb;
	rx_ring->rcb_tail = NEXT_INDEX(free_index, 1, rx_ring->free_list_size);

	mutex_exit(&rx_ring->recycle_lock);

	/*
	 * The atomic operation on the number of the available rx control
	 * blocks in the free list is used to make the recycling mutual
	 * exclusive with the receiving.
	 */
	atomic_inc_32(&rx_ring->rcb_free);
	ASSERT(rx_ring->rcb_free <= rx_ring->free_list_size);
}

/*
 * igb_rx_copy - Use copy to process the received packet
 *
 * This function will use bcopy to process the packet
 * and send the copied packet upstream
 */
static mblk_t *
igb_rx_copy(igb_rx_ring_t *rx_ring, uint32_t index, uint32_t pkt_len)
{
	rx_control_block_t *current_rcb;
	mblk_t *mp;

	current_rcb = rx_ring->work_list[index];

	DMA_SYNC(&current_rcb->rx_buf, DDI_DMA_SYNC_FORKERNEL);

	/*
	 * Allocate buffer to receive this packet
	 */
	mp = allocb(pkt_len + IPHDR_ALIGN_ROOM, 0);
	if (mp == NULL) {
		igb_log(rx_ring->igb, "igb_rx_copy: allocate buffer failed");
		return (NULL);
	}

	/*
	 * Copy the data received into the new cluster
	 */
	mp->b_rptr += IPHDR_ALIGN_ROOM;
	bcopy(current_rcb->rx_buf.address, mp->b_rptr, pkt_len);
	mp->b_wptr = mp->b_rptr + pkt_len;

	return (mp);
}

/*
 * igb_rx_bind - Use existing DMA buffer to build mblk for receiving
 *
 * This function will use pre-bound DMA buffer to receive the packet
 * and build mblk that will be sent upstream.
 */
static mblk_t *
igb_rx_bind(igb_rx_ring_t *rx_ring, uint32_t index, uint32_t pkt_len)
{
	rx_control_block_t *current_rcb;
	rx_control_block_t *free_rcb;
	uint32_t free_index;
	mblk_t *mp;

	/*
	 * If the free list is empty, we cannot proceed to send
	 * the current DMA buffer upstream. We'll have to return
	 * and use bcopy to process the packet.
	 */
	if (igb_atomic_reserve(&rx_ring->rcb_free, 1) < 0)
		return (NULL);

	current_rcb = rx_ring->work_list[index];
	/*
	 * If the mp of the rx control block is NULL, try to do
	 * desballoc again.
	 */
	if (current_rcb->mp == NULL) {
		current_rcb->mp = desballoc((unsigned char *)
		    (current_rcb->rx_buf.address - IPHDR_ALIGN_ROOM),
		    (current_rcb->rx_buf.size + IPHDR_ALIGN_ROOM),
		    0, &current_rcb->free_rtn);
		/*
		 * If it is failed to built a mblk using the current
		 * DMA buffer, we have to return and use bcopy to
		 * process the packet.
		 */
		if (current_rcb->mp == NULL) {
			atomic_inc_32(&rx_ring->rcb_free);
			return (NULL);
		}
	}
	/*
	 * Sync up the data received
	 */
	DMA_SYNC(&current_rcb->rx_buf, DDI_DMA_SYNC_FORKERNEL);

	mp = current_rcb->mp;
	current_rcb->mp = NULL;
	current_rcb->state = RCB_SENDUP;

	mp->b_wptr = mp->b_rptr + pkt_len;
	mp->b_next = mp->b_cont = NULL;

	/*
	 * Strip off one free rx control block from the free list
	 */
	free_index = rx_ring->rcb_head;
	free_rcb = rx_ring->free_list[free_index];
	ASSERT(free_rcb != NULL);
	rx_ring->free_list[free_index] = NULL;
	rx_ring->rcb_head = NEXT_INDEX(free_index, 1, rx_ring->free_list_size);

	/*
	 * Put the rx control block to the work list
	 */
	rx_ring->work_list[index] = free_rcb;

	return (mp);
}

/*
 * igb_rx_assoc_hcksum
 *
 * Check the rx hardware checksum status and associate the hcksum flags
 */
static void
igb_rx_assoc_hcksum(mblk_t *mp, uint32_t status_error)
{
	uint32_t hcksum_flags = 0;

	/* Ignore Checksum Indication */
	if (status_error & E1000_RXD_STAT_IXSM)
		return;

	/*
	 * Check TCP/UDP checksum
	 */
	if (((status_error & E1000_RXD_STAT_TCPCS) ||
	    (status_error & E1000_RXD_STAT_UDPCS)) &&
	    !(status_error & E1000_RXDEXT_STATERR_TCPE))
		hcksum_flags |= HCK_FULLCKSUM | HCK_FULLCKSUM_OK;

	/*
	 * Check IP Checksum
	 */
	if ((status_error & E1000_RXD_STAT_IPCS) &&
	    !(status_error & E1000_RXDEXT_STATERR_IPE))
		hcksum_flags |= HCK_IPV4_HDRCKSUM;

	if (hcksum_flags != 0) {
		(void) hcksum_assoc(mp,
		    NULL, NULL, 0, 0, 0, 0, hcksum_flags, 0);
	}
}

/*
 * igb_rx - Receive the data of one ring
 *
 * This function goes throught h/w descriptor in one specified rx ring,
 * receives the data if the descriptor status shows the data is ready.
 * It returns a chain of mblks containing the received data, to be
 * passed up to mac_rx().
 */
mblk_t *
igb_rx(igb_rx_ring_t *rx_ring)
{
	union e1000_adv_rx_desc *current_rbd;
	rx_control_block_t *current_rcb;
	mblk_t *mp;
	mblk_t *mblk_head;
	mblk_t **mblk_tail;
	uint32_t rx_next;
	uint32_t rx_tail;
	uint32_t pkt_len;
	uint32_t status_error;
	uint32_t pkt_num;
	igb_t *igb = rx_ring->igb;

	mblk_head = NULL;
	mblk_tail = &mblk_head;

	/*
	 * Sync the receive descriptors before
	 * accepting the packets
	 */
	DMA_SYNC(&rx_ring->rbd_area, DDI_DMA_SYNC_FORKERNEL);

	/*
	 * Get the start point of rx bd ring which should be examined
	 * during this cycle.
	 */
	rx_next = rx_ring->rbd_next;

	current_rbd = &rx_ring->rbd_ring[rx_next];
	pkt_num = 0;
	status_error = current_rbd->wb.upper.status_error;
	while (status_error & E1000_RXD_STAT_DD) {
		/*
		 * If hardware has found the errors, but the error
		 * is hardware checksum error, here does not discard the
		 * packet, and let upper layer compute the checksum;
		 * Otherwise discard the packet.
		 */
		if ((status_error & E1000_RXDEXT_ERR_FRAME_ERR_MASK) ||
		    !(status_error & E1000_RXD_STAT_EOP)) {
			IGB_DEBUG_STAT(rx_ring->stat_frame_error);
			goto rx_discard;
		}

		IGB_DEBUG_STAT_COND(rx_ring->stat_cksum_error,
		    (status_error & E1000_RXDEXT_STATERR_TCPE) ||
		    (status_error & E1000_RXDEXT_STATERR_IPE));

		pkt_len = current_rbd->wb.upper.length;
		mp = NULL;
		/*
		 * For packets with length more than the copy threshold,
		 * we'll firstly try to use the existed DMA buffer to built
		 * a mblk and send the mblk upstream.
		 *
		 * If the first method fails, or the packet length is less
		 * than the copy threshold, we'll allocate a new mblk and
		 * copy the packet data to the mblk.
		 */
		if (pkt_len > rx_ring->copy_thresh)
			mp = igb_rx_bind(rx_ring, rx_next, pkt_len);

		if (mp == NULL)
			mp = igb_rx_copy(rx_ring, rx_next, pkt_len);

		if (mp != NULL) {
			/*
			 * Check h/w checksum offload status
			 */
			if (igb->rx_hcksum_enable)
				igb_rx_assoc_hcksum(mp, status_error);

			*mblk_tail = mp;
			mblk_tail = &mp->b_next;
		}

rx_discard:
		/*
		 * Reset rx descriptor read bits
		 */
		current_rcb = rx_ring->work_list[rx_next];
		current_rbd->read.pkt_addr = current_rcb->rx_buf.dma_address;
		current_rbd->read.hdr_addr = 0;

		rx_next = NEXT_INDEX(rx_next, 1, rx_ring->ring_size);

		/*
		 * The receive function is in interrupt context, so here
		 * limit_per_intr is used to avoid doing receiving too long
		 * per interrupt.
		 */
		if (++pkt_num > rx_ring->limit_per_intr) {
			IGB_DEBUG_STAT(rx_ring->stat_exceed_pkt);
			break;
		}

		current_rbd = &rx_ring->rbd_ring[rx_next];
		status_error = current_rbd->wb.upper.status_error;
	}

	DMA_SYNC(&rx_ring->rbd_area, DDI_DMA_SYNC_FORDEV);

	rx_ring->rbd_next = rx_next;

	/*
	 * Update the h/w tail accordingly
	 */
	rx_tail = PREV_INDEX(rx_next, 1, rx_ring->ring_size);

	E1000_WRITE_REG(&igb->hw, E1000_RDT(rx_ring->index), rx_tail);

	return (mblk_head);
}