/*
 * This file is based on code from OCTEON SDK by Cavium Networks.
 *
 * Copyright (c) 2003-2010 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.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/cache.h>
#include <linux/cpumask.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ip.h>
#include <linux/string.h>
#include <linux/prefetch.h>
#include <linux/ratelimit.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <net/dst.h>
#ifdef CONFIG_XFRM
#include <linux/xfrm.h>
#include <net/xfrm.h>
#endif /* CONFIG_XFRM */

#include <asm/octeon/octeon.h>

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

#include <asm/octeon/cvmx-helper.h>
#include <asm/octeon/cvmx-wqe.h>
#include <asm/octeon/cvmx-fau.h>
#include <asm/octeon/cvmx-pow.h>
#include <asm/octeon/cvmx-pip.h>
#include <asm/octeon/cvmx-scratch.h>

#include <asm/octeon/cvmx-gmxx-defs.h>

static struct napi_struct cvm_oct_napi;

/**
 * cvm_oct_do_interrupt - interrupt handler.
 * @cpl: Interrupt number. Unused
 * @dev_id: Cookie to identify the device. Unused
 *
 * The interrupt occurs whenever the POW has packets in our group.
 *
 */
static irqreturn_t cvm_oct_do_interrupt(int cpl, void *dev_id)
{
        /* Disable the IRQ and start napi_poll. */
        disable_irq_nosync(OCTEON_IRQ_WORKQ0 + pow_receive_group);
        napi_schedule(&cvm_oct_napi);

        return IRQ_HANDLED;
}

/**
 * cvm_oct_check_rcv_error - process receive errors
 * @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)
{
        int port;

        if (octeon_has_feature(OCTEON_FEATURE_PKND))
                port = work->word0.pip.cn68xx.pknd;
        else
                port = work->word1.cn38xx.ipprt;

        if ((work->word2.snoip.err_code == 10) && (work->word1.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 (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(port);
                int index = cvmx_helper_get_interface_index_num(port);
                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) {
                        u8 *ptr =
                            cvmx_phys_to_ptr(work->packet_ptr.s.addr);
                        int i = 0;

                        while (i < work->word1.len - 1) {
                                if (*ptr != 0x55)
                                        break;
                                ptr++;
                                i++;
                        }

                        if (*ptr == 0xd5) {
                                /* Port received 0xd5 preamble */
                                work->packet_ptr.s.addr += i + 1;
                                work->word1.len -= i + 5;
                        } else if ((*ptr & 0xf) == 0xd) {
                                /* Port received 0xd preamble */
                                work->packet_ptr.s.addr += i;
                                work->word1.len -= i + 4;
                                for (i = 0; i < work->word1.len; i++) {
                                        *ptr =
                                            ((*ptr & 0xf0) >> 4) |
                                            ((*(ptr + 1) & 0xf) << 4);
                                        ptr++;
                                }
                        } else {
                                printk_ratelimited("Port %d unknown preamble, packet dropped\n",
                                                   port);
                                cvm_oct_free_work(work);
                                return 1;
                        }
                }
        } else {
                printk_ratelimited("Port %d receive error code %d, packet dropped\n",
                                   port, work->word2.snoip.err_code);
                cvm_oct_free_work(work);
                return 1;
        }

        return 0;
}

/**
 * cvm_oct_napi_poll - the NAPI poll function.
 * @napi: The NAPI instance, or null if called from cvm_oct_poll_controller
 * @budget: Maximum number of packets to receive.
 *
 * Returns the number of packets processed.
 */
static int cvm_oct_napi_poll(struct napi_struct *napi, int budget)
{
        const int       coreid = cvmx_get_core_num();
        u64     old_group_mask;
        u64     old_scratch;
        int             rx_count = 0;
        int             did_work_request = 0;
        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) */
        if (OCTEON_IS_MODEL(OCTEON_CN68XX)) {
                old_group_mask = cvmx_read_csr(CVMX_SSO_PPX_GRP_MSK(coreid));
                cvmx_write_csr(CVMX_SSO_PPX_GRP_MSK(coreid),
                                1ull << pow_receive_group);
                cvmx_read_csr(CVMX_SSO_PPX_GRP_MSK(coreid)); /* Flush */
        } else {
                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);
                did_work_request = 1;
        }

        while (rx_count < budget) {
                struct sk_buff *skb = NULL;
                struct sk_buff **pskb = NULL;
                int skb_in_hw;
                cvmx_wqe_t *work;
                int port;

                if (USE_ASYNC_IOBDMA && did_work_request)
                        work = cvmx_pow_work_response_async(CVMX_SCR_SCRATCH);
                else
                        work = cvmx_pow_work_request_sync(CVMX_POW_NO_WAIT);

                prefetch(work);
                did_work_request = 0;
                if (!work) {
                        if (OCTEON_IS_MODEL(OCTEON_CN68XX)) {
                                cvmx_write_csr(CVMX_SSO_WQ_IQ_DIS,
                                               1ull << pow_receive_group);
                                cvmx_write_csr(CVMX_SSO_WQ_INT,
                                               1ull << pow_receive_group);
                        } else {
                                union cvmx_pow_wq_int wq_int;

                                wq_int.u64 = 0;
                                wq_int.s.iq_dis = 1 << pow_receive_group;
                                wq_int.s.wq_int = 1 << pow_receive_group;
                                cvmx_write_csr(CVMX_POW_WQ_INT, wq_int.u64);
                        }
                        break;
                }
                pskb = (struct sk_buff **)
                        (cvm_oct_get_buffer_ptr(work->packet_ptr) -
                        sizeof(void *));
                prefetch(pskb);

                if (USE_ASYNC_IOBDMA && rx_count < (budget - 1)) {
                        cvmx_pow_work_request_async_nocheck(CVMX_SCR_SCRATCH,
                                                            CVMX_POW_NO_WAIT);
                        did_work_request = 1;
                }
                rx_count++;

                skb_in_hw = work->word2.s.bufs == 1;
                if (likely(skb_in_hw)) {
                        skb = *pskb;
                        prefetch(&skb->head);
                        prefetch(&skb->len);
                }

                if (octeon_has_feature(OCTEON_FEATURE_PKND))
                        port = work->word0.pip.cn68xx.pknd;
                else
                        port = work->word1.cn38xx.ipprt;

                prefetch(cvm_oct_device[port]);

                /* 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)) {
                        skb->data = skb->head + work->packet_ptr.s.addr -
                                cvmx_ptr_to_phys(skb->head);
                        prefetch(skb->data);
                        skb->len = work->word1.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->word1.len);
                        if (!skb) {
                                cvm_oct_free_work(work);
                                continue;
                        }

                        /*
                         * Check if we've received a packet that was
                         * entirely stored in the work entry.
                         */
                        if (unlikely(work->word2.s.bufs == 0)) {
                                u8 *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->word1.len), ptr,
                                       work->word1.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->word1.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);
                                        len -= segment_size;
                                        segment_ptr = next_ptr;
                                }
                        }
                        packet_not_copied = 0;
                }
                if (likely((port < TOTAL_NUMBER_OF_PORTS) &&
                           cvm_oct_device[port])) {
                        struct net_device *dev = cvm_oct_device[port];
                        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 ||
                                             !work->word2.s.tcp_or_udp))
                                        skb->ip_summed = CHECKSUM_NONE;
                                else
                                        skb->ip_summed = CHECKSUM_UNNECESSARY;

                                /* Increment RX stats for virtual ports */
                                if (port >= CVMX_PIP_NUM_INPUT_PORTS) {
                                        priv->stats.rx_packets++;
                                        priv->stats.rx_bytes += skb->len;
                                }
                                netif_receive_skb(skb);
                        } else {
                                /*
                                 * Drop any packet received for a device that
                                 * isn't up.
                                 */
                                priv->stats.rx_dropped++;
                                dev_kfree_skb_irq(skb);
                        }
                } else {
                        /*
                         * Drop any packet received for a device that
                         * doesn't exist.
                         */
                        printk_ratelimited("Port %d not controlled by Linux, packet dropped\n",
                                   port);
                        dev_kfree_skb_irq(skb);
                }
                /*
                 * Check to see if the skbuff and work share the same
                 * packet buffer.
                 */
                if (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, 1);
                } else {
                        cvm_oct_free_work(work);
                }
        }
        /* Restore the original POW group mask */
        if (OCTEON_IS_MODEL(OCTEON_CN68XX)) {
                cvmx_write_csr(CVMX_SSO_PPX_GRP_MSK(coreid), old_group_mask);
                cvmx_read_csr(CVMX_SSO_PPX_GRP_MSK(coreid)); /* Flush */
        } else {
                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);
        }
        cvm_oct_rx_refill_pool(0);

        if (rx_count < budget && napi) {
                /* No more work */
                napi_complete(napi);
                enable_irq(OCTEON_IRQ_WORKQ0 + pow_receive_group);
        }
        return rx_count;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
/**
 * cvm_oct_poll_controller - poll for receive packets
 * device.
 *
 * @dev:    Device to poll. Unused
 */
void cvm_oct_poll_controller(struct net_device *dev)
{
        cvm_oct_napi_poll(NULL, 16);
}
#endif

void cvm_oct_rx_initialize(void)
{
        int i;
        struct net_device *dev_for_napi = NULL;

        for (i = 0; i < TOTAL_NUMBER_OF_PORTS; i++) {
                if (cvm_oct_device[i]) {
                        dev_for_napi = cvm_oct_device[i];
                        break;
                }
        }

        if (!dev_for_napi)
                panic("No net_devices were allocated.");

        netif_napi_add(dev_for_napi, &cvm_oct_napi, cvm_oct_napi_poll,
                       rx_napi_weight);
        napi_enable(&cvm_oct_napi);

        /* Register an IRQ handler to receive POW interrupts */
        i = request_irq(OCTEON_IRQ_WORKQ0 + pow_receive_group,
                        cvm_oct_do_interrupt, 0, "Ethernet", cvm_oct_device);

        if (i)
                panic("Could not acquire Ethernet IRQ %d\n",
                      OCTEON_IRQ_WORKQ0 + pow_receive_group);

        disable_irq_nosync(OCTEON_IRQ_WORKQ0 + pow_receive_group);

        /* Enable POW interrupt when our port has at least one packet */
        if (OCTEON_IS_MODEL(OCTEON_CN68XX)) {
                union cvmx_sso_wq_int_thrx int_thr;
                union cvmx_pow_wq_int_pc int_pc;

                int_thr.u64 = 0;
                int_thr.s.tc_en = 1;
                int_thr.s.tc_thr = 1;
                cvmx_write_csr(CVMX_SSO_WQ_INT_THRX(pow_receive_group),
                               int_thr.u64);

                int_pc.u64 = 0;
                int_pc.s.pc_thr = 5;
                cvmx_write_csr(CVMX_SSO_WQ_INT_PC, int_pc.u64);
        } else {
                union cvmx_pow_wq_int_thrx int_thr;
                union cvmx_pow_wq_int_pc int_pc;

                int_thr.u64 = 0;
                int_thr.s.tc_en = 1;
                int_thr.s.tc_thr = 1;
                cvmx_write_csr(CVMX_POW_WQ_INT_THRX(pow_receive_group),
                               int_thr.u64);

                int_pc.u64 = 0;
                int_pc.s.pc_thr = 5;
                cvmx_write_csr(CVMX_POW_WQ_INT_PC, int_pc.u64);
        }

        /* Schedule NAPI now. This will indirectly enable the interrupt. */
        napi_schedule(&cvm_oct_napi);
}

void cvm_oct_rx_shutdown(void)
{
        netif_napi_del(&cvm_oct_napi);
}