/*
 * 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);
}