/**********************************************************************
 * 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);
}