/*
 * Huawei HiNIC PCI Express Linux driver
 * Copyright(c) 2017 Huawei Technologies Co., Ltd
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/pci.h>
#include <linux/device.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/u64_stats_sync.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/skbuff.h>
#include <linux/dma-mapping.h>
#include <linux/prefetch.h>
#include <asm/barrier.h>

#include "hinic_common.h"
#include "hinic_hw_if.h"
#include "hinic_hw_wqe.h"
#include "hinic_hw_wq.h"
#include "hinic_hw_qp.h"
#include "hinic_hw_dev.h"
#include "hinic_rx.h"
#include "hinic_dev.h"

#define RX_IRQ_NO_PENDING               0
#define RX_IRQ_NO_COALESC               0
#define RX_IRQ_NO_LLI_TIMER             0
#define RX_IRQ_NO_CREDIT                0
#define RX_IRQ_NO_RESEND_TIMER          0

/**
 * hinic_rxq_clean_stats - Clean the statistics of specific queue
 * @rxq: Logical Rx Queue
 **/
void hinic_rxq_clean_stats(struct hinic_rxq *rxq)
{
        struct hinic_rxq_stats *rxq_stats = &rxq->rxq_stats;

        u64_stats_update_begin(&rxq_stats->syncp);
        rxq_stats->pkts  = 0;
        rxq_stats->bytes = 0;
        u64_stats_update_end(&rxq_stats->syncp);
}

/**
 * hinic_rxq_get_stats - get statistics of Rx Queue
 * @rxq: Logical Rx Queue
 * @stats: return updated stats here
 **/
void hinic_rxq_get_stats(struct hinic_rxq *rxq, struct hinic_rxq_stats *stats)
{
        struct hinic_rxq_stats *rxq_stats = &rxq->rxq_stats;
        unsigned int start;

        u64_stats_update_begin(&stats->syncp);
        do {
                start = u64_stats_fetch_begin(&rxq_stats->syncp);
                stats->pkts = rxq_stats->pkts;
                stats->bytes = rxq_stats->bytes;
        } while (u64_stats_fetch_retry(&rxq_stats->syncp, start));
        u64_stats_update_end(&stats->syncp);
}

/**
 * rxq_stats_init - Initialize the statistics of specific queue
 * @rxq: Logical Rx Queue
 **/
static void rxq_stats_init(struct hinic_rxq *rxq)
{
        struct hinic_rxq_stats *rxq_stats = &rxq->rxq_stats;

        u64_stats_init(&rxq_stats->syncp);
        hinic_rxq_clean_stats(rxq);
}

/**
 * rx_alloc_skb - allocate skb and map it to dma address
 * @rxq: rx queue
 * @dma_addr: returned dma address for the skb
 *
 * Return skb
 **/
static struct sk_buff *rx_alloc_skb(struct hinic_rxq *rxq,
                                    dma_addr_t *dma_addr)
{
        struct hinic_dev *nic_dev = netdev_priv(rxq->netdev);
        struct hinic_hwdev *hwdev = nic_dev->hwdev;
        struct hinic_hwif *hwif = hwdev->hwif;
        struct pci_dev *pdev = hwif->pdev;
        struct sk_buff *skb;
        dma_addr_t addr;
        int err;

        skb = netdev_alloc_skb_ip_align(rxq->netdev, rxq->rq->buf_sz);
        if (!skb) {
                netdev_err(rxq->netdev, "Failed to allocate Rx SKB\n");
                return NULL;
        }

        addr = dma_map_single(&pdev->dev, skb->data, rxq->rq->buf_sz,
                              DMA_FROM_DEVICE);
        err = dma_mapping_error(&pdev->dev, addr);
        if (err) {
                dev_err(&pdev->dev, "Failed to map Rx DMA, err = %d\n", err);
                goto err_rx_map;
        }

        *dma_addr = addr;
        return skb;

err_rx_map:
        dev_kfree_skb_any(skb);
        return NULL;
}

/**
 * rx_unmap_skb - unmap the dma address of the skb
 * @rxq: rx queue
 * @dma_addr: dma address of the skb
 **/
static void rx_unmap_skb(struct hinic_rxq *rxq, dma_addr_t dma_addr)
{
        struct hinic_dev *nic_dev = netdev_priv(rxq->netdev);
        struct hinic_hwdev *hwdev = nic_dev->hwdev;
        struct hinic_hwif *hwif = hwdev->hwif;
        struct pci_dev *pdev = hwif->pdev;

        dma_unmap_single(&pdev->dev, dma_addr, rxq->rq->buf_sz,
                         DMA_FROM_DEVICE);
}

/**
 * rx_free_skb - unmap and free skb
 * @rxq: rx queue
 * @skb: skb to free
 * @dma_addr: dma address of the skb
 **/
static void rx_free_skb(struct hinic_rxq *rxq, struct sk_buff *skb,
                        dma_addr_t dma_addr)
{
        rx_unmap_skb(rxq, dma_addr);
        dev_kfree_skb_any(skb);
}

/**
 * rx_alloc_pkts - allocate pkts in rx queue
 * @rxq: rx queue
 *
 * Return number of skbs allocated
 **/
static int rx_alloc_pkts(struct hinic_rxq *rxq)
{
        struct hinic_dev *nic_dev = netdev_priv(rxq->netdev);
        struct hinic_rq_wqe *rq_wqe;
        unsigned int free_wqebbs;
        struct hinic_sge sge;
        dma_addr_t dma_addr;
        struct sk_buff *skb;
        int i, alloc_more;
        u16 prod_idx;

        free_wqebbs = hinic_get_rq_free_wqebbs(rxq->rq);
        alloc_more = 0;

        /* Limit the allocation chunks */
        if (free_wqebbs > nic_dev->rx_weight)
                free_wqebbs = nic_dev->rx_weight;

        for (i = 0; i < free_wqebbs; i++) {
                skb = rx_alloc_skb(rxq, &dma_addr);
                if (!skb) {
                        netdev_err(rxq->netdev, "Failed to alloc Rx skb\n");
                        alloc_more = 1;
                        goto skb_out;
                }

                hinic_set_sge(&sge, dma_addr, skb->len);

                rq_wqe = hinic_rq_get_wqe(rxq->rq, HINIC_RQ_WQE_SIZE,
                                          &prod_idx);
                if (!rq_wqe) {
                        rx_free_skb(rxq, skb, dma_addr);
                        alloc_more = 1;
                        goto skb_out;
                }

                hinic_rq_prepare_wqe(rxq->rq, prod_idx, rq_wqe, &sge);

                hinic_rq_write_wqe(rxq->rq, prod_idx, rq_wqe, skb);
        }

skb_out:
        if (i) {
                wmb();  /* write all the wqes before update PI */

                hinic_rq_update(rxq->rq, prod_idx);
        }

        if (alloc_more)
                tasklet_schedule(&rxq->rx_task);

        return i;
}

/**
 * free_all_rx_skbs - free all skbs in rx queue
 * @rxq: rx queue
 **/
static void free_all_rx_skbs(struct hinic_rxq *rxq)
{
        struct hinic_rq *rq = rxq->rq;
        struct hinic_hw_wqe *hw_wqe;
        struct hinic_sge sge;
        u16 ci;

        while ((hw_wqe = hinic_read_wqe(rq->wq, HINIC_RQ_WQE_SIZE, &ci))) {
                if (IS_ERR(hw_wqe))
                        break;

                hinic_rq_get_sge(rq, &hw_wqe->rq_wqe, ci, &sge);

                hinic_put_wqe(rq->wq, HINIC_RQ_WQE_SIZE);

                rx_free_skb(rxq, rq->saved_skb[ci], hinic_sge_to_dma(&sge));
        }
}

/**
 * rx_alloc_task - tasklet for queue allocation
 * @data: rx queue
 **/
static void rx_alloc_task(unsigned long data)
{
        struct hinic_rxq *rxq = (struct hinic_rxq *)data;

        (void)rx_alloc_pkts(rxq);
}

/**
 * rx_recv_jumbo_pkt - Rx handler for jumbo pkt
 * @rxq: rx queue
 * @head_skb: the first skb in the list
 * @left_pkt_len: left size of the pkt exclude head skb
 * @ci: consumer index
 *
 * Return number of wqes that used for the left of the pkt
 **/
static int rx_recv_jumbo_pkt(struct hinic_rxq *rxq, struct sk_buff *head_skb,
                             unsigned int left_pkt_len, u16 ci)
{
        struct sk_buff *skb, *curr_skb = head_skb;
        struct hinic_rq_wqe *rq_wqe;
        unsigned int curr_len;
        struct hinic_sge sge;
        int num_wqes = 0;

        while (left_pkt_len > 0) {
                rq_wqe = hinic_rq_read_next_wqe(rxq->rq, HINIC_RQ_WQE_SIZE,
                                                &skb, &ci);

                num_wqes++;

                hinic_rq_get_sge(rxq->rq, rq_wqe, ci, &sge);

                rx_unmap_skb(rxq, hinic_sge_to_dma(&sge));

                prefetch(skb->data);

                curr_len = (left_pkt_len > HINIC_RX_BUF_SZ) ? HINIC_RX_BUF_SZ :
                            left_pkt_len;

                left_pkt_len -= curr_len;

                __skb_put(skb, curr_len);

                if (curr_skb == head_skb)
                        skb_shinfo(head_skb)->frag_list = skb;
                else
                        curr_skb->next = skb;

                head_skb->len += skb->len;
                head_skb->data_len += skb->len;
                head_skb->truesize += skb->truesize;

                curr_skb = skb;
        }

        return num_wqes;
}

/**
 * rxq_recv - Rx handler
 * @rxq: rx queue
 * @budget: maximum pkts to process
 *
 * Return number of pkts received
 **/
static int rxq_recv(struct hinic_rxq *rxq, int budget)
{
        struct hinic_qp *qp = container_of(rxq->rq, struct hinic_qp, rq);
        u64 pkt_len = 0, rx_bytes = 0;
        struct hinic_rq_wqe *rq_wqe;
        int num_wqes, pkts = 0;
        struct hinic_sge sge;
        struct sk_buff *skb;
        u16 ci;

        while (pkts < budget) {
                num_wqes = 0;

                rq_wqe = hinic_rq_read_wqe(rxq->rq, HINIC_RQ_WQE_SIZE, &skb,
                                           &ci);
                if (!rq_wqe)
                        break;

                hinic_rq_get_sge(rxq->rq, rq_wqe, ci, &sge);

                rx_unmap_skb(rxq, hinic_sge_to_dma(&sge));

                prefetch(skb->data);

                pkt_len = sge.len;

                if (pkt_len <= HINIC_RX_BUF_SZ) {
                        __skb_put(skb, pkt_len);
                } else {
                        __skb_put(skb, HINIC_RX_BUF_SZ);
                        num_wqes = rx_recv_jumbo_pkt(rxq, skb, pkt_len -
                                                     HINIC_RX_BUF_SZ, ci);
                }

                hinic_rq_put_wqe(rxq->rq, ci,
                                 (num_wqes + 1) * HINIC_RQ_WQE_SIZE);

                skb_record_rx_queue(skb, qp->q_id);
                skb->protocol = eth_type_trans(skb, rxq->netdev);

                napi_gro_receive(&rxq->napi, skb);

                pkts++;
                rx_bytes += pkt_len;
        }

        if (pkts)
                tasklet_schedule(&rxq->rx_task); /* hinic_rx_alloc_pkts */

        u64_stats_update_begin(&rxq->rxq_stats.syncp);
        rxq->rxq_stats.pkts += pkts;
        rxq->rxq_stats.bytes += rx_bytes;
        u64_stats_update_end(&rxq->rxq_stats.syncp);

        return pkts;
}

static int rx_poll(struct napi_struct *napi, int budget)
{
        struct hinic_rxq *rxq = container_of(napi, struct hinic_rxq, napi);
        struct hinic_rq *rq = rxq->rq;
        int pkts;

        pkts = rxq_recv(rxq, budget);
        if (pkts >= budget)
                return budget;

        napi_complete(napi);
        enable_irq(rq->irq);
        return pkts;
}

static void rx_add_napi(struct hinic_rxq *rxq)
{
        struct hinic_dev *nic_dev = netdev_priv(rxq->netdev);

        netif_napi_add(rxq->netdev, &rxq->napi, rx_poll, nic_dev->rx_weight);
        napi_enable(&rxq->napi);
}

static void rx_del_napi(struct hinic_rxq *rxq)
{
        napi_disable(&rxq->napi);
        netif_napi_del(&rxq->napi);
}

static irqreturn_t rx_irq(int irq, void *data)
{
        struct hinic_rxq *rxq = (struct hinic_rxq *)data;
        struct hinic_rq *rq = rxq->rq;
        struct hinic_dev *nic_dev;

        /* Disable the interrupt until napi will be completed */
        disable_irq_nosync(rq->irq);

        nic_dev = netdev_priv(rxq->netdev);
        hinic_hwdev_msix_cnt_set(nic_dev->hwdev, rq->msix_entry);

        napi_schedule(&rxq->napi);
        return IRQ_HANDLED;
}

static int rx_request_irq(struct hinic_rxq *rxq)
{
        struct hinic_dev *nic_dev = netdev_priv(rxq->netdev);
        struct hinic_hwdev *hwdev = nic_dev->hwdev;
        struct hinic_rq *rq = rxq->rq;
        int err;

        rx_add_napi(rxq);

        hinic_hwdev_msix_set(hwdev, rq->msix_entry,
                             RX_IRQ_NO_PENDING, RX_IRQ_NO_COALESC,
                             RX_IRQ_NO_LLI_TIMER, RX_IRQ_NO_CREDIT,
                             RX_IRQ_NO_RESEND_TIMER);

        err = request_irq(rq->irq, rx_irq, 0, rxq->irq_name, rxq);
        if (err) {
                rx_del_napi(rxq);
                return err;
        }

        return 0;
}

static void rx_free_irq(struct hinic_rxq *rxq)
{
        struct hinic_rq *rq = rxq->rq;

        free_irq(rq->irq, rxq);
        rx_del_napi(rxq);
}

/**
 * hinic_init_rxq - Initialize the Rx Queue
 * @rxq: Logical Rx Queue
 * @rq: Hardware Rx Queue to connect the Logical queue with
 * @netdev: network device to connect the Logical queue with
 *
 * Return 0 - Success, negative - Failure
 **/
int hinic_init_rxq(struct hinic_rxq *rxq, struct hinic_rq *rq,
                   struct net_device *netdev)
{
        struct hinic_qp *qp = container_of(rq, struct hinic_qp, rq);
        int err, pkts, irqname_len;

        rxq->netdev = netdev;
        rxq->rq = rq;

        rxq_stats_init(rxq);

        irqname_len = snprintf(NULL, 0, "hinic_rxq%d", qp->q_id) + 1;
        rxq->irq_name = devm_kzalloc(&netdev->dev, irqname_len, GFP_KERNEL);
        if (!rxq->irq_name)
                return -ENOMEM;

        sprintf(rxq->irq_name, "hinic_rxq%d", qp->q_id);

        tasklet_init(&rxq->rx_task, rx_alloc_task, (unsigned long)rxq);

        pkts = rx_alloc_pkts(rxq);
        if (!pkts) {
                err = -ENOMEM;
                goto err_rx_pkts;
        }

        err = rx_request_irq(rxq);
        if (err) {
                netdev_err(netdev, "Failed to request Rx irq\n");
                goto err_req_rx_irq;
        }

        return 0;

err_req_rx_irq:
err_rx_pkts:
        tasklet_kill(&rxq->rx_task);
        free_all_rx_skbs(rxq);
        devm_kfree(&netdev->dev, rxq->irq_name);
        return err;
}

/**
 * hinic_clean_rxq - Clean the Rx Queue
 * @rxq: Logical Rx Queue
 **/
void hinic_clean_rxq(struct hinic_rxq *rxq)
{
        struct net_device *netdev = rxq->netdev;

        rx_free_irq(rxq);

        tasklet_kill(&rxq->rx_task);
        free_all_rx_skbs(rxq);
        devm_kfree(&netdev->dev, rxq->irq_name);
}