drivers/staging/octeon/ethernet-rx.c - kernel/prism - Git at Google

 /**********************************************************************
  * Author: Cavium Networks
  *
  * Contact: support@caviumnetworks.com
  * This file is part of the OCTEON SDK
  *
  * Copyright (c) 2003-2007 Cavium Networks
  *
  * This file 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 file is distributed in the hope that it will be useful, but
  * AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or
  * NONINFRINGEMENT.  See the GNU General Public License for more
  * details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this file; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  * or visit http://www.gnu.org/licenses/.
  *
  * This file may also be available under a different license from Cavium.
  * Contact Cavium Networks for more information
 **********************************************************************/
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/cache.h>
 #include <linux/netdevice.h>
 #include <linux/init.h>
 #include <linux/etherdevice.h>
 #include <linux/ip.h>
 #include <linux/string.h>
 #include <linux/prefetch.h>
 #include <linux/ethtool.h>
 #include <linux/mii.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
 #include <net/dst.h>
 #ifdef CONFIG_XFRM
 #include <linux/xfrm.h>
 #include <net/xfrm.h>
 #endif /* CONFIG_XFRM */

 #include <asm/atomic.h>

 #include <asm/octeon/octeon.h>

 #include "ethernet-defines.h"
 #include "octeon-ethernet.h"
 #include "ethernet-mem.h"
 #include "ethernet-util.h"

 #include "cvmx-helper.h"
 #include "cvmx-wqe.h"
 #include "cvmx-fau.h"
 #include "cvmx-pow.h"
 #include "cvmx-pip.h"
 #include "cvmx-scratch.h"

 #include "cvmx-gmxx-defs.h"

 struct cvm_tasklet_wrapper {
 	struct tasklet_struct t;
 };

 /*
  * Aligning the tasklet_struct on cachline boundries seems to decrease
  * throughput even though in theory it would reduce contantion on the
  * cache lines containing the locks.
  */

 static struct cvm_tasklet_wrapper cvm_oct_tasklet[NR_CPUS];

 /**
  * Interrupt handler. The interrupt occurs whenever the POW
  * transitions from 0->1 packets in our group.
  *
  * @cpl:
  * @dev_id:
  * @regs:
  * Returns
  */
 irqreturn_t cvm_oct_do_interrupt(int cpl, void *dev_id)
 {
 	/* Acknowledge the interrupt */
 	if (INTERRUPT_LIMIT)
 		cvmx_write_csr(CVMX_POW_WQ_INT, 1 << pow_receive_group);
 	else
 		cvmx_write_csr(CVMX_POW_WQ_INT, 0x10001 << pow_receive_group);
 	preempt_disable();
 	tasklet_schedule(&cvm_oct_tasklet[smp_processor_id()].t);
 	preempt_enable();
 	return IRQ_HANDLED;
 }

 #ifdef CONFIG_NET_POLL_CONTROLLER
 /**
  * This is called when the kernel needs to manually poll the
  * device. For Octeon, this is simply calling the interrupt
  * handler. We actually poll all the devices, not just the
  * one supplied.
  *
  * @dev:    Device to poll. Unused
  */
 void cvm_oct_poll_controller(struct net_device *dev)
 {
 	preempt_disable();
 	tasklet_schedule(&cvm_oct_tasklet[smp_processor_id()].t);
 	preempt_enable();
 }
 #endif

 /**
  * This is called on receive errors, and determines if the packet
  * can be dropped early-on in cvm_oct_tasklet_rx().
  *
  * @work: Work queue entry pointing to the packet.
  * Returns Non-zero if the packet can be dropped, zero otherwise.
  */
 static inline int cvm_oct_check_rcv_error(cvmx_wqe_t *work)
 {
 	if ((work->word2.snoip.err_code == 10) && (work->len <= 64)) {
 		/*
 		 * Ignore length errors on min size packets. Some
 		 * equipment incorrectly pads packets to 64+4FCS
 		 * instead of 60+4FCS.  Note these packets still get
 		 * counted as frame errors.
 		 */
 	} else
 	    if (USE_10MBPS_PREAMBLE_WORKAROUND
 		&& ((work->word2.snoip.err_code == 5)
 		    || (work->word2.snoip.err_code == 7))) {

 		/*
 		 * We received a packet with either an alignment error
 		 * or a FCS error. This may be signalling that we are
 		 * running 10Mbps with GMXX_RXX_FRM_CTL[PRE_CHK}
 		 * off. If this is the case we need to parse the
 		 * packet to determine if we can remove a non spec
 		 * preamble and generate a correct packet.
 		 */
 		int interface = cvmx_helper_get_interface_num(work->ipprt);
 		int index = cvmx_helper_get_interface_index_num(work->ipprt);
 		union cvmx_gmxx_rxx_frm_ctl gmxx_rxx_frm_ctl;
 		gmxx_rxx_frm_ctl.u64 =
 		    cvmx_read_csr(CVMX_GMXX_RXX_FRM_CTL(index, interface));
 		if (gmxx_rxx_frm_ctl.s.pre_chk == 0) {

 			uint8_t *ptr =
 			    cvmx_phys_to_ptr(work->packet_ptr.s.addr);
 			int i = 0;

 			while (i < work->len - 1) {
 				if (*ptr != 0x55)
 					break;
 				ptr++;
 				i++;
 			}

 			if (*ptr == 0xd5) {
 				/*
 				   DEBUGPRINT("Port %d received 0xd5 preamble\n", work->ipprt);
 				 */
 				work->packet_ptr.s.addr += i + 1;
 				work->len -= i + 5;
 			} else if ((*ptr & 0xf) == 0xd) {
 				/*
 				   DEBUGPRINT("Port %d received 0x?d preamble\n", work->ipprt);
 				 */
 				work->packet_ptr.s.addr += i;
 				work->len -= i + 4;
 				for (i = 0; i < work->len; i++) {
 					*ptr =
 					    ((*ptr & 0xf0) >> 4) |
 					    ((*(ptr + 1) & 0xf) << 4);
 					ptr++;
 				}
 			} else {
 				DEBUGPRINT("Port %d unknown preamble, packet "
 					   "dropped\n",
 				     work->ipprt);
 				/*
 				   cvmx_helper_dump_packet(work);
 				 */
 				cvm_oct_free_work(work);
 				return 1;
 			}
 		}
 	} else {
 		DEBUGPRINT("Port %d receive error code %d, packet dropped\n",
 			   work->ipprt, work->word2.snoip.err_code);
 		cvm_oct_free_work(work);
 		return 1;
 	}

 	return 0;
 }

 /**
  * Tasklet function that is scheduled on a core when an interrupt occurs.
  *
  * @unused:
  */
 void cvm_oct_tasklet_rx(unsigned long unused)
 {
 	const int coreid = cvmx_get_core_num();
 	uint64_t old_group_mask;
 	uint64_t old_scratch;
 	int rx_count = 0;
 	int number_to_free;
 	int num_freed;
 	int packet_not_copied;

 	/* Prefetch cvm_oct_device since we know we need it soon */
 	prefetch(cvm_oct_device);

 	if (USE_ASYNC_IOBDMA) {
 		/* Save scratch in case userspace is using it */
 		CVMX_SYNCIOBDMA;
 		old_scratch = cvmx_scratch_read64(CVMX_SCR_SCRATCH);
 	}

 	/* Only allow work for our group (and preserve priorities) */
 	old_group_mask = cvmx_read_csr(CVMX_POW_PP_GRP_MSKX(coreid));
 	cvmx_write_csr(CVMX_POW_PP_GRP_MSKX(coreid),
 		       (old_group_mask & ~0xFFFFull) | 1 << pow_receive_group);

 	if (USE_ASYNC_IOBDMA)
 		cvmx_pow_work_request_async(CVMX_SCR_SCRATCH, CVMX_POW_NO_WAIT);

 	while (1) {
 		struct sk_buff *skb = NULL;
 		int skb_in_hw;
 		cvmx_wqe_t *work;

 		if (USE_ASYNC_IOBDMA) {
 			work = cvmx_pow_work_response_async(CVMX_SCR_SCRATCH);
 		} else {
 			if ((INTERRUPT_LIMIT == 0)
 			    || likely(rx_count < MAX_RX_PACKETS))
 				work =
 				    cvmx_pow_work_request_sync
 				    (CVMX_POW_NO_WAIT);
 			else
 				work = NULL;
 		}
 		prefetch(work);
 		if (work == NULL)
 			break;

 		/*
 		 * Limit each core to processing MAX_RX_PACKETS
 		 * packets without a break.  This way the RX can't
 		 * starve the TX task.
 		 */
 		if (USE_ASYNC_IOBDMA) {

 			if ((INTERRUPT_LIMIT == 0)
 			    || likely(rx_count < MAX_RX_PACKETS))
 				cvmx_pow_work_request_async_nocheck
 				    (CVMX_SCR_SCRATCH, CVMX_POW_NO_WAIT);
 			else {
 				cvmx_scratch_write64(CVMX_SCR_SCRATCH,
 						     0x8000000000000000ull);
 				cvmx_pow_tag_sw_null_nocheck();
 			}
 		}

 		skb_in_hw = USE_SKBUFFS_IN_HW && work->word2.s.bufs == 1;
 		if (likely(skb_in_hw)) {
 			skb =
 			    *(struct sk_buff
 			      **)(cvm_oct_get_buffer_ptr(work->packet_ptr) -
 				  sizeof(void *));
 			prefetch(&skb->head);
 			prefetch(&skb->len);
 		}
 		prefetch(cvm_oct_device[work->ipprt]);

 		rx_count++;
 		/* Immediately throw away all packets with receive errors */
 		if (unlikely(work->word2.snoip.rcv_error)) {
 			if (cvm_oct_check_rcv_error(work))
 				continue;
 		}

 		/*
 		 * We can only use the zero copy path if skbuffs are
 		 * in the FPA pool and the packet fits in a single
 		 * buffer.
 		 */
 		if (likely(skb_in_hw)) {
 			/*
 			 * This calculation was changed in case the
 			 * skb header is using a different address
 			 * aliasing type than the buffer. It doesn't
 			 * make any differnece now, but the new one is
 			 * more correct.
 			 */
 			skb->data =
 			    skb->head + work->packet_ptr.s.addr -
 			    cvmx_ptr_to_phys(skb->head);
 			prefetch(skb->data);
 			skb->len = work->len;
 			skb_set_tail_pointer(skb, skb->len);
 			packet_not_copied = 1;
 		} else {

 			/*
 			 * We have to copy the packet. First allocate
 			 * an skbuff for it.
 			 */
 			skb = dev_alloc_skb(work->len);
 			if (!skb) {
 				DEBUGPRINT("Port %d failed to allocate "
 					   "skbuff, packet dropped\n",
 				     work->ipprt);
 				cvm_oct_free_work(work);
 				continue;
 			}

 			/*
 			 * Check if we've received a packet that was
 			 * entirely stored in the work entry. This is
 			 * untested.
 			 */
 			if (unlikely(work->word2.s.bufs == 0)) {
 				uint8_t *ptr = work->packet_data;

 				if (likely(!work->word2.s.not_IP)) {
 					/*
 					 * The beginning of the packet
 					 * moves for IP packets.
 					 */
 					if (work->word2.s.is_v6)
 						ptr += 2;
 					else
 						ptr += 6;
 				}
 				memcpy(skb_put(skb, work->len), ptr, work->len);
 				/* No packet buffers to free */
 			} else {
 				int segments = work->word2.s.bufs;
 				union cvmx_buf_ptr segment_ptr =
 					work->packet_ptr;
 				int len = work->len;

 				while (segments--) {
 					union cvmx_buf_ptr next_ptr =
 					    *(union cvmx_buf_ptr *)
 					    cvmx_phys_to_ptr(segment_ptr.s.
 							     addr - 8);
 			/*
 			 * Octeon Errata PKI-100: The segment size is
 			 * wrong. Until it is fixed, calculate the
 			 * segment size based on the packet pool
 			 * buffer size. When it is fixed, the
 			 * following line should be replaced with this
 			 * one: int segment_size =
 			 * segment_ptr.s.size;
 			 */
 					int segment_size =
 					    CVMX_FPA_PACKET_POOL_SIZE -
 					    (segment_ptr.s.addr -
 					     (((segment_ptr.s.addr >> 7) -
 					       segment_ptr.s.back) << 7));
 					/* Don't copy more than what is left
 					   in the packet */
 					if (segment_size > len)
 						segment_size = len;
 					/* Copy the data into the packet */
 					memcpy(skb_put(skb, segment_size),
 					       cvmx_phys_to_ptr(segment_ptr.s.
 								addr),
 					       segment_size);
 					/* Reduce the amount of bytes left
 					   to copy */
 					len -= segment_size;
 					segment_ptr = next_ptr;
 				}
 			}
 			packet_not_copied = 0;
 		}

 		if (likely((work->ipprt < TOTAL_NUMBER_OF_PORTS) &&
 			   cvm_oct_device[work->ipprt])) {
 			struct net_device *dev = cvm_oct_device[work->ipprt];
 			struct octeon_ethernet *priv = netdev_priv(dev);

 			/* Only accept packets for devices
 			   that are currently up */
 			if (likely(dev->flags & IFF_UP)) {
 				skb->protocol = eth_type_trans(skb, dev);
 				skb->dev = dev;

 				if (unlikely
 				    (work->word2.s.not_IP
 				     || work->word2.s.IP_exc
 				     || work->word2.s.L4_error))
 					skb->ip_summed = CHECKSUM_NONE;
 				else
 					skb->ip_summed = CHECKSUM_UNNECESSARY;

 				/* Increment RX stats for virtual ports */
 				if (work->ipprt >= CVMX_PIP_NUM_INPUT_PORTS) {
 #ifdef CONFIG_64BIT
 					atomic64_add(1, (atomic64_t *)&priv->stats.rx_packets);
 					atomic64_add(skb->len, (atomic64_t *)&priv->stats.rx_bytes);
 #else
 					atomic_add(1, (atomic_t *)&priv->stats.rx_packets);
 					atomic_add(skb->len, (atomic_t *)&priv->stats.rx_bytes);
 #endif
 				}
 				netif_receive_skb(skb);
 			} else {
 				/*
 				 * Drop any packet received for a
 				 * device that isn't up.
 				 */
 				/*
 				   DEBUGPRINT("%s: Device not up, packet dropped\n",
 				   dev->name);
 				 */
 #ifdef CONFIG_64BIT
 				atomic64_add(1, (atomic64_t *)&priv->stats.rx_dropped);
 #else
 				atomic_add(1, (atomic_t *)&priv->stats.rx_dropped);
 #endif
 				dev_kfree_skb_irq(skb);
 			}
 		} else {
 			/*
 			 * Drop any packet received for a device that
 			 * doesn't exist.
 			 */
 			DEBUGPRINT("Port %d not controlled by Linux, packet "
 				   "dropped\n",
 			     work->ipprt);
 			dev_kfree_skb_irq(skb);
 		}
 		/*
 		 * Check to see if the skbuff and work share the same
 		 * packet buffer.
 		 */
 		if (USE_SKBUFFS_IN_HW && likely(packet_not_copied)) {
 			/*
 			 * This buffer needs to be replaced, increment
 			 * the number of buffers we need to free by
 			 * one.
 			 */
 			cvmx_fau_atomic_add32(FAU_NUM_PACKET_BUFFERS_TO_FREE,
 					      1);

 			cvmx_fpa_free(work, CVMX_FPA_WQE_POOL,
 				      DONT_WRITEBACK(1));
 		} else {
 			cvm_oct_free_work(work);
 		}
 	}

 	/* Restore the original POW group mask */
 	cvmx_write_csr(CVMX_POW_PP_GRP_MSKX(coreid), old_group_mask);
 	if (USE_ASYNC_IOBDMA) {
 		/* Restore the scratch area */
 		cvmx_scratch_write64(CVMX_SCR_SCRATCH, old_scratch);
 	}

 	if (USE_SKBUFFS_IN_HW) {
 		/* Refill the packet buffer pool */
 		number_to_free =
 		    cvmx_fau_fetch_and_add32(FAU_NUM_PACKET_BUFFERS_TO_FREE, 0);

 		if (number_to_free > 0) {
 			cvmx_fau_atomic_add32(FAU_NUM_PACKET_BUFFERS_TO_FREE,
 					      -number_to_free);
 			num_freed =
 			    cvm_oct_mem_fill_fpa(CVMX_FPA_PACKET_POOL,
 						 CVMX_FPA_PACKET_POOL_SIZE,
 						 number_to_free);
 			if (num_freed != number_to_free) {
 				cvmx_fau_atomic_add32
 				    (FAU_NUM_PACKET_BUFFERS_TO_FREE,
 				     number_to_free - num_freed);
 			}
 		}
 	}
 }

 void cvm_oct_rx_initialize(void)
 {
 	int i;
 	/* Initialize all of the tasklets */
 	for (i = 0; i < NR_CPUS; i++)
 		tasklet_init(&cvm_oct_tasklet[i].t, cvm_oct_tasklet_rx, 0);
 }

 void cvm_oct_rx_shutdown(void)
 {
 	int i;
 	/* Shutdown all of the tasklets */
 	for (i = 0; i < NR_CPUS; i++)
 		tasklet_kill(&cvm_oct_tasklet[i].t);
 }
	/**********************************************************************
	* Author: Cavium Networks
	*
	* Contact: support@caviumnetworks.com
	* This file is part of the OCTEON SDK
	*
	* Copyright (c) 2003-2007 Cavium Networks
	*
	* This file 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 file is distributed in the hope that it will be useful, but
	* AS-IS and WITHOUT ANY WARRANTY; without even the implied warranty
	* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, TITLE, or
	* NONINFRINGEMENT. See the GNU General Public License for more
	* details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this file; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	* or visit http://www.gnu.org/licenses/.
	*
	* This file may also be available under a different license from Cavium.
	* Contact Cavium Networks for more information
	**********************************************************************/
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/cache.h>
	#include <linux/netdevice.h>
	#include <linux/init.h>
	#include <linux/etherdevice.h>
	#include <linux/ip.h>
	#include <linux/string.h>
	#include <linux/prefetch.h>
	#include <linux/ethtool.h>
	#include <linux/mii.h>
	#include <linux/seq_file.h>
	#include <linux/proc_fs.h>
	#include <net/dst.h>
	#ifdef CONFIG_XFRM
	#include <linux/xfrm.h>
	#include <net/xfrm.h>
	#endif /* CONFIG_XFRM */

	#include <asm/atomic.h>

	#include <asm/octeon/octeon.h>

	#include "ethernet-defines.h"
	#include "octeon-ethernet.h"
	#include "ethernet-mem.h"
	#include "ethernet-util.h"

	#include "cvmx-helper.h"
	#include "cvmx-wqe.h"
	#include "cvmx-fau.h"
	#include "cvmx-pow.h"
	#include "cvmx-pip.h"
	#include "cvmx-scratch.h"

	#include "cvmx-gmxx-defs.h"

	struct cvm_tasklet_wrapper {
	struct tasklet_struct t;
	};

	/*
	* Aligning the tasklet_struct on cachline boundries seems to decrease
	* throughput even though in theory it would reduce contantion on the
	* cache lines containing the locks.
	*/

	static struct cvm_tasklet_wrapper cvm_oct_tasklet[NR_CPUS];

	/**
	* Interrupt handler. The interrupt occurs whenever the POW
	* transitions from 0->1 packets in our group.
	*
	* @cpl:
	* @dev_id:
	* @regs:
	* Returns
	*/
	irqreturn_t cvm_oct_do_interrupt(int cpl, void *dev_id)
	{
	/* Acknowledge the interrupt */
	if (INTERRUPT_LIMIT)
	cvmx_write_csr(CVMX_POW_WQ_INT, 1 << pow_receive_group);
	else
	cvmx_write_csr(CVMX_POW_WQ_INT, 0x10001 << pow_receive_group);
	preempt_disable();
	tasklet_schedule(&cvm_oct_tasklet[smp_processor_id()].t);
	preempt_enable();
	return IRQ_HANDLED;
	}

	#ifdef CONFIG_NET_POLL_CONTROLLER
	/**
	* This is called when the kernel needs to manually poll the
	* device. For Octeon, this is simply calling the interrupt
	* handler. We actually poll all the devices, not just the
	* one supplied.
	*
	* @dev: Device to poll. Unused
	*/
	void cvm_oct_poll_controller(struct net_device *dev)
	{
	preempt_disable();
	tasklet_schedule(&cvm_oct_tasklet[smp_processor_id()].t);
	preempt_enable();
	}
	#endif

	/**
	* This is called on receive errors, and determines if the packet
	* can be dropped early-on in cvm_oct_tasklet_rx().
	*
	* @work: Work queue entry pointing to the packet.
	* Returns Non-zero if the packet can be dropped, zero otherwise.
	*/
	static inline int cvm_oct_check_rcv_error(cvmx_wqe_t *work)
	{
	if ((work->word2.snoip.err_code == 10) && (work->len <= 64)) {
	/*
	* Ignore length errors on min size packets. Some
	* equipment incorrectly pads packets to 64+4FCS
	* instead of 60+4FCS. Note these packets still get
	* counted as frame errors.
	*/
	} else
	if (USE_10MBPS_PREAMBLE_WORKAROUND
	&& ((work->word2.snoip.err_code == 5)
	\|\| (work->word2.snoip.err_code == 7))) {

	/*
	* We received a packet with either an alignment error
	* or a FCS error. This may be signalling that we are
	* running 10Mbps with GMXX_RXX_FRM_CTL[PRE_CHK}
	* off. If this is the case we need to parse the
	* packet to determine if we can remove a non spec
	* preamble and generate a correct packet.
	*/
	int interface = cvmx_helper_get_interface_num(work->ipprt);
	int index = cvmx_helper_get_interface_index_num(work->ipprt);
	union cvmx_gmxx_rxx_frm_ctl gmxx_rxx_frm_ctl;
	gmxx_rxx_frm_ctl.u64 =
	cvmx_read_csr(CVMX_GMXX_RXX_FRM_CTL(index, interface));
	if (gmxx_rxx_frm_ctl.s.pre_chk == 0) {

	uint8_t *ptr =
	cvmx_phys_to_ptr(work->packet_ptr.s.addr);
	int i = 0;

	while (i < work->len - 1) {
	if (*ptr != 0x55)
	break;
	ptr++;
	i++;
	}

	if (*ptr == 0xd5) {
	/*
	DEBUGPRINT("Port %d received 0xd5 preamble\n", work->ipprt);
	*/
	work->packet_ptr.s.addr += i + 1;
	work->len -= i + 5;
	} else if ((*ptr & 0xf) == 0xd) {
	/*
	DEBUGPRINT("Port %d received 0x?d preamble\n", work->ipprt);
	*/
	work->packet_ptr.s.addr += i;
	work->len -= i + 4;
	for (i = 0; i < work->len; i++) {
	*ptr =
	((*ptr & 0xf0) >> 4) \|
	((*(ptr + 1) & 0xf) << 4);
	ptr++;
	}
	} else {
	DEBUGPRINT("Port %d unknown preamble, packet "
	"dropped\n",
	work->ipprt);
	/*
	cvmx_helper_dump_packet(work);
	*/
	cvm_oct_free_work(work);
	return 1;
	}
	}
	} else {
	DEBUGPRINT("Port %d receive error code %d, packet dropped\n",
	work->ipprt, work->word2.snoip.err_code);
	cvm_oct_free_work(work);
	return 1;
	}

	return 0;
	}

	/**
	* Tasklet function that is scheduled on a core when an interrupt occurs.
	*
	* @unused:
	*/
	void cvm_oct_tasklet_rx(unsigned long unused)
	{
	const int coreid = cvmx_get_core_num();
	uint64_t old_group_mask;
	uint64_t old_scratch;
	int rx_count = 0;
	int number_to_free;
	int num_freed;
	int packet_not_copied;

	/* Prefetch cvm_oct_device since we know we need it soon */
	prefetch(cvm_oct_device);

	if (USE_ASYNC_IOBDMA) {
	/* Save scratch in case userspace is using it */
	CVMX_SYNCIOBDMA;
	old_scratch = cvmx_scratch_read64(CVMX_SCR_SCRATCH);
	}

	/* Only allow work for our group (and preserve priorities) */
	old_group_mask = cvmx_read_csr(CVMX_POW_PP_GRP_MSKX(coreid));
	cvmx_write_csr(CVMX_POW_PP_GRP_MSKX(coreid),
	(old_group_mask & ~0xFFFFull) \| 1 << pow_receive_group);

	if (USE_ASYNC_IOBDMA)
	cvmx_pow_work_request_async(CVMX_SCR_SCRATCH, CVMX_POW_NO_WAIT);

	while (1) {
	struct sk_buff *skb = NULL;
	int skb_in_hw;
	cvmx_wqe_t *work;

	if (USE_ASYNC_IOBDMA) {
	work = cvmx_pow_work_response_async(CVMX_SCR_SCRATCH);
	} else {
	if ((INTERRUPT_LIMIT == 0)
	\|\| likely(rx_count < MAX_RX_PACKETS))
	work =
	cvmx_pow_work_request_sync
	(CVMX_POW_NO_WAIT);
	else
	work = NULL;
	}
	prefetch(work);
	if (work == NULL)
	break;

	/*
	* Limit each core to processing MAX_RX_PACKETS
	* packets without a break. This way the RX can't
	* starve the TX task.
	*/
	if (USE_ASYNC_IOBDMA) {

	if ((INTERRUPT_LIMIT == 0)
	\|\| likely(rx_count < MAX_RX_PACKETS))
	cvmx_pow_work_request_async_nocheck
	(CVMX_SCR_SCRATCH, CVMX_POW_NO_WAIT);
	else {
	cvmx_scratch_write64(CVMX_SCR_SCRATCH,
	0x8000000000000000ull);
	cvmx_pow_tag_sw_null_nocheck();
	}
	}

	skb_in_hw = USE_SKBUFFS_IN_HW && work->word2.s.bufs == 1;
	if (likely(skb_in_hw)) {
	skb =
	*(struct sk_buff
	**)(cvm_oct_get_buffer_ptr(work->packet_ptr) -
	sizeof(void *));
	prefetch(&skb->head);
	prefetch(&skb->len);
	}
	prefetch(cvm_oct_device[work->ipprt]);

	rx_count++;
	/* Immediately throw away all packets with receive errors */
	if (unlikely(work->word2.snoip.rcv_error)) {
	if (cvm_oct_check_rcv_error(work))
	continue;
	}

	/*
	* We can only use the zero copy path if skbuffs are
	* in the FPA pool and the packet fits in a single
	* buffer.
	*/
	if (likely(skb_in_hw)) {
	/*
	* This calculation was changed in case the
	* skb header is using a different address
	* aliasing type than the buffer. It doesn't
	* make any differnece now, but the new one is
	* more correct.
	*/
	skb->data =
	skb->head + work->packet_ptr.s.addr -
	cvmx_ptr_to_phys(skb->head);
	prefetch(skb->data);
	skb->len = work->len;
	skb_set_tail_pointer(skb, skb->len);
	packet_not_copied = 1;
	} else {

	/*
	* We have to copy the packet. First allocate
	* an skbuff for it.
	*/
	skb = dev_alloc_skb(work->len);
	if (!skb) {
	DEBUGPRINT("Port %d failed to allocate "
	"skbuff, packet dropped\n",
	work->ipprt);
	cvm_oct_free_work(work);
	continue;
	}

	/*
	* Check if we've received a packet that was
	* entirely stored in the work entry. This is
	* untested.
	*/
	if (unlikely(work->word2.s.bufs == 0)) {
	uint8_t *ptr = work->packet_data;

	if (likely(!work->word2.s.not_IP)) {
	/*
	* The beginning of the packet
	* moves for IP packets.
	*/
	if (work->word2.s.is_v6)
	ptr += 2;
	else
	ptr += 6;
	}
	memcpy(skb_put(skb, work->len), ptr, work->len);
	/* No packet buffers to free */
	} else {
	int segments = work->word2.s.bufs;
	union cvmx_buf_ptr segment_ptr =
	work->packet_ptr;
	int len = work->len;

	while (segments--) {
	union cvmx_buf_ptr next_ptr =
	(union cvmx_buf_ptr )
	cvmx_phys_to_ptr(segment_ptr.s.
	addr - 8);
	/*
	* Octeon Errata PKI-100: The segment size is
	* wrong. Until it is fixed, calculate the
	* segment size based on the packet pool
	* buffer size. When it is fixed, the
	* following line should be replaced with this
	* one: int segment_size =
	* segment_ptr.s.size;
	*/
	int segment_size =
	CVMX_FPA_PACKET_POOL_SIZE -
	(segment_ptr.s.addr -
	(((segment_ptr.s.addr >> 7) -
	segment_ptr.s.back) << 7));
	/* Don't copy more than what is left
	in the packet */
	if (segment_size > len)
	segment_size = len;
	/* Copy the data into the packet */
	memcpy(skb_put(skb, segment_size),
	cvmx_phys_to_ptr(segment_ptr.s.
	addr),
	segment_size);
	/* Reduce the amount of bytes left
	to copy */
	len -= segment_size;
	segment_ptr = next_ptr;
	}
	}
	packet_not_copied = 0;
	}

	if (likely((work->ipprt < TOTAL_NUMBER_OF_PORTS) &&
	cvm_oct_device[work->ipprt])) {
	struct net_device *dev = cvm_oct_device[work->ipprt];
	struct octeon_ethernet *priv = netdev_priv(dev);

	/* Only accept packets for devices
	that are currently up */
	if (likely(dev->flags & IFF_UP)) {
	skb->protocol = eth_type_trans(skb, dev);
	skb->dev = dev;

	if (unlikely
	(work->word2.s.not_IP
	\|\| work->word2.s.IP_exc
	\|\| work->word2.s.L4_error))
	skb->ip_summed = CHECKSUM_NONE;
	else
	skb->ip_summed = CHECKSUM_UNNECESSARY;

	/* Increment RX stats for virtual ports */
	if (work->ipprt >= CVMX_PIP_NUM_INPUT_PORTS) {
	#ifdef CONFIG_64BIT
	atomic64_add(1, (atomic64_t *)&priv->stats.rx_packets);
	atomic64_add(skb->len, (atomic64_t *)&priv->stats.rx_bytes);
	#else
	atomic_add(1, (atomic_t *)&priv->stats.rx_packets);
	atomic_add(skb->len, (atomic_t *)&priv->stats.rx_bytes);
	#endif
	}
	netif_receive_skb(skb);
	} else {
	/*
	* Drop any packet received for a
	* device that isn't up.
	*/
	/*
	DEBUGPRINT("%s: Device not up, packet dropped\n",
	dev->name);
	*/
	#ifdef CONFIG_64BIT
	atomic64_add(1, (atomic64_t *)&priv->stats.rx_dropped);
	#else
	atomic_add(1, (atomic_t *)&priv->stats.rx_dropped);
	#endif
	dev_kfree_skb_irq(skb);
	}
	} else {
	/*
	* Drop any packet received for a device that
	* doesn't exist.
	*/
	DEBUGPRINT("Port %d not controlled by Linux, packet "
	"dropped\n",
	work->ipprt);
	dev_kfree_skb_irq(skb);
	}
	/*
	* Check to see if the skbuff and work share the same
	* packet buffer.
	*/
	if (USE_SKBUFFS_IN_HW && likely(packet_not_copied)) {
	/*
	* This buffer needs to be replaced, increment
	* the number of buffers we need to free by
	* one.
	*/
	cvmx_fau_atomic_add32(FAU_NUM_PACKET_BUFFERS_TO_FREE,
	1);

	cvmx_fpa_free(work, CVMX_FPA_WQE_POOL,
	DONT_WRITEBACK(1));
	} else {
	cvm_oct_free_work(work);
	}
	}

	/* Restore the original POW group mask */
	cvmx_write_csr(CVMX_POW_PP_GRP_MSKX(coreid), old_group_mask);
	if (USE_ASYNC_IOBDMA) {
	/* Restore the scratch area */
	cvmx_scratch_write64(CVMX_SCR_SCRATCH, old_scratch);
	}

	if (USE_SKBUFFS_IN_HW) {
	/* Refill the packet buffer pool */
	number_to_free =
	cvmx_fau_fetch_and_add32(FAU_NUM_PACKET_BUFFERS_TO_FREE, 0);

	if (number_to_free > 0) {
	cvmx_fau_atomic_add32(FAU_NUM_PACKET_BUFFERS_TO_FREE,
	-number_to_free);
	num_freed =
	cvm_oct_mem_fill_fpa(CVMX_FPA_PACKET_POOL,
	CVMX_FPA_PACKET_POOL_SIZE,
	number_to_free);
	if (num_freed != number_to_free) {
	cvmx_fau_atomic_add32
	(FAU_NUM_PACKET_BUFFERS_TO_FREE,
	number_to_free - num_freed);
	}
	}
	}
	}

	void cvm_oct_rx_initialize(void)
	{
	int i;
	/* Initialize all of the tasklets */
	for (i = 0; i < NR_CPUS; i++)
	tasklet_init(&cvm_oct_tasklet[i].t, cvm_oct_tasklet_rx, 0);
	}

	void cvm_oct_rx_shutdown(void)
	{
	int i;
	/* Shutdown all of the tasklets */
	for (i = 0; i < NR_CPUS; i++)
	tasklet_kill(&cvm_oct_tasklet[i].t);
	}