/* MOXA ART Ethernet (RTL8201CP) driver.
 *
 * Copyright (C) 2013 Jonas Jensen
 *
 * Jonas Jensen <jonas.jensen@gmail.com>
 *
 * Based on code from
 * Moxa Technology Co., Ltd. <www.moxa.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/dma-mapping.h>
#include <linux/ethtool.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/crc32.h>
#include <linux/crc32c.h>
#include <linux/circ_buf.h>

#include "moxart_ether.h"

static inline void moxart_desc_write(u32 data, __le32 *desc)
{
        *desc = cpu_to_le32(data);
}

static inline u32 moxart_desc_read(__le32 *desc)
{
        return le32_to_cpu(*desc);
}

static inline void moxart_emac_write(struct net_device *ndev,
                                     unsigned int reg, unsigned long value)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        writel(value, priv->base + reg);
}

static void moxart_update_mac_address(struct net_device *ndev)
{
        moxart_emac_write(ndev, REG_MAC_MS_ADDRESS,
                          ((ndev->dev_addr[0] << 8) | (ndev->dev_addr[1])));
        moxart_emac_write(ndev, REG_MAC_MS_ADDRESS + 4,
                          ((ndev->dev_addr[2] << 24) |
                           (ndev->dev_addr[3] << 16) |
                           (ndev->dev_addr[4] << 8) |
                           (ndev->dev_addr[5])));
}

static int moxart_set_mac_address(struct net_device *ndev, void *addr)
{
        struct sockaddr *address = addr;

        eth_hw_addr_set(ndev, address->sa_data);
        moxart_update_mac_address(ndev);

        return 0;
}

static void moxart_mac_free_memory(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        if (priv->tx_desc_base)
                dma_free_coherent(&priv->pdev->dev,
                                  TX_REG_DESC_SIZE * TX_DESC_NUM,
                                  priv->tx_desc_base, priv->tx_base);

        if (priv->rx_desc_base)
                dma_free_coherent(&priv->pdev->dev,
                                  RX_REG_DESC_SIZE * RX_DESC_NUM,
                                  priv->rx_desc_base, priv->rx_base);

        kfree(priv->tx_buf_base);
        kfree(priv->rx_buf_base);
}

static void moxart_mac_reset(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        writel(SW_RST, priv->base + REG_MAC_CTRL);
        while (readl(priv->base + REG_MAC_CTRL) & SW_RST)
                mdelay(10);

        writel(0, priv->base + REG_INTERRUPT_MASK);

        priv->reg_maccr = RX_BROADPKT | FULLDUP | CRC_APD | RX_FTL;
}

static void moxart_mac_enable(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        writel(0x00001010, priv->base + REG_INT_TIMER_CTRL);
        writel(0x00000001, priv->base + REG_APOLL_TIMER_CTRL);
        writel(0x00000390, priv->base + REG_DMA_BLEN_CTRL);

        priv->reg_imr |= (RPKT_FINISH_M | XPKT_FINISH_M);
        writel(priv->reg_imr, priv->base + REG_INTERRUPT_MASK);

        priv->reg_maccr |= (RCV_EN | XMT_EN | RDMA_EN | XDMA_EN);
        writel(priv->reg_maccr, priv->base + REG_MAC_CTRL);
}

static void moxart_mac_setup_desc_ring(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);
        void *desc;
        int i;

        for (i = 0; i < TX_DESC_NUM; i++) {
                desc = priv->tx_desc_base + i * TX_REG_DESC_SIZE;
                memset(desc, 0, TX_REG_DESC_SIZE);

                priv->tx_buf[i] = priv->tx_buf_base + priv->tx_buf_size * i;
        }
        moxart_desc_write(TX_DESC1_END, desc + TX_REG_OFFSET_DESC1);

        priv->tx_head = 0;
        priv->tx_tail = 0;

        for (i = 0; i < RX_DESC_NUM; i++) {
                desc = priv->rx_desc_base + i * RX_REG_DESC_SIZE;
                memset(desc, 0, RX_REG_DESC_SIZE);
                moxart_desc_write(RX_DESC0_DMA_OWN, desc + RX_REG_OFFSET_DESC0);
                moxart_desc_write(RX_BUF_SIZE & RX_DESC1_BUF_SIZE_MASK,
                       desc + RX_REG_OFFSET_DESC1);

                priv->rx_buf[i] = priv->rx_buf_base + priv->rx_buf_size * i;
                priv->rx_mapping[i] = dma_map_single(&priv->pdev->dev,
                                                     priv->rx_buf[i],
                                                     priv->rx_buf_size,
                                                     DMA_FROM_DEVICE);
                if (dma_mapping_error(&priv->pdev->dev, priv->rx_mapping[i]))
                        netdev_err(ndev, "DMA mapping error\n");

                moxart_desc_write(priv->rx_mapping[i],
                       desc + RX_REG_OFFSET_DESC2 + RX_DESC2_ADDRESS_PHYS);
                moxart_desc_write((uintptr_t)priv->rx_buf[i],
                       desc + RX_REG_OFFSET_DESC2 + RX_DESC2_ADDRESS_VIRT);
        }
        moxart_desc_write(RX_DESC1_END, desc + RX_REG_OFFSET_DESC1);

        priv->rx_head = 0;

        /* reset the MAC controller TX/RX descriptor base address */
        writel(priv->tx_base, priv->base + REG_TXR_BASE_ADDRESS);
        writel(priv->rx_base, priv->base + REG_RXR_BASE_ADDRESS);
}

static int moxart_mac_open(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        napi_enable(&priv->napi);

        moxart_mac_reset(ndev);
        moxart_update_mac_address(ndev);
        moxart_mac_setup_desc_ring(ndev);
        moxart_mac_enable(ndev);
        netif_start_queue(ndev);

        netdev_dbg(ndev, "%s: IMR=0x%x, MACCR=0x%x\n",
                   __func__, readl(priv->base + REG_INTERRUPT_MASK),
                   readl(priv->base + REG_MAC_CTRL));

        return 0;
}

static int moxart_mac_stop(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);
        int i;

        napi_disable(&priv->napi);

        netif_stop_queue(ndev);

        /* disable all interrupts */
        writel(0, priv->base + REG_INTERRUPT_MASK);

        /* disable all functions */
        writel(0, priv->base + REG_MAC_CTRL);

        /* unmap areas mapped in moxart_mac_setup_desc_ring() */
        for (i = 0; i < RX_DESC_NUM; i++)
                dma_unmap_single(&priv->pdev->dev, priv->rx_mapping[i],
                                 priv->rx_buf_size, DMA_FROM_DEVICE);

        return 0;
}

static int moxart_rx_poll(struct napi_struct *napi, int budget)
{
        struct moxart_mac_priv_t *priv = container_of(napi,
                                                      struct moxart_mac_priv_t,
                                                      napi);
        struct net_device *ndev = priv->ndev;
        struct sk_buff *skb;
        void *desc;
        unsigned int desc0, len;
        int rx_head = priv->rx_head;
        int rx = 0;

        while (rx < budget) {
                desc = priv->rx_desc_base + (RX_REG_DESC_SIZE * rx_head);
                desc0 = moxart_desc_read(desc + RX_REG_OFFSET_DESC0);
                rmb(); /* ensure desc0 is up to date */

                if (desc0 & RX_DESC0_DMA_OWN)
                        break;

                if (desc0 & (RX_DESC0_ERR | RX_DESC0_CRC_ERR | RX_DESC0_FTL |
                             RX_DESC0_RUNT | RX_DESC0_ODD_NB)) {
                        net_dbg_ratelimited("packet error\n");
                        ndev->stats.rx_dropped++;
                        ndev->stats.rx_errors++;
                        goto rx_next;
                }

                len = desc0 & RX_DESC0_FRAME_LEN_MASK;

                if (len > RX_BUF_SIZE)
                        len = RX_BUF_SIZE;

                dma_sync_single_for_cpu(&priv->pdev->dev,
                                        priv->rx_mapping[rx_head],
                                        priv->rx_buf_size, DMA_FROM_DEVICE);
                skb = netdev_alloc_skb_ip_align(ndev, len);

                if (unlikely(!skb)) {
                        net_dbg_ratelimited("netdev_alloc_skb_ip_align failed\n");
                        ndev->stats.rx_dropped++;
                        ndev->stats.rx_errors++;
                        goto rx_next;
                }

                memcpy(skb->data, priv->rx_buf[rx_head], len);
                skb_put(skb, len);
                skb->protocol = eth_type_trans(skb, ndev);
                napi_gro_receive(&priv->napi, skb);
                rx++;

                ndev->stats.rx_packets++;
                ndev->stats.rx_bytes += len;
                if (desc0 & RX_DESC0_MULTICAST)
                        ndev->stats.multicast++;

rx_next:
                wmb(); /* prevent setting ownership back too early */
                moxart_desc_write(RX_DESC0_DMA_OWN, desc + RX_REG_OFFSET_DESC0);

                rx_head = RX_NEXT(rx_head);
                priv->rx_head = rx_head;
        }

        if (rx < budget)
                napi_complete_done(napi, rx);

        priv->reg_imr |= RPKT_FINISH_M;
        writel(priv->reg_imr, priv->base + REG_INTERRUPT_MASK);

        return rx;
}

static int moxart_tx_queue_space(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        return CIRC_SPACE(priv->tx_head, priv->tx_tail, TX_DESC_NUM);
}

static void moxart_tx_finished(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);
        unsigned int tx_head = priv->tx_head;
        unsigned int tx_tail = priv->tx_tail;

        while (tx_tail != tx_head) {
                dma_unmap_single(&priv->pdev->dev, priv->tx_mapping[tx_tail],
                                 priv->tx_len[tx_tail], DMA_TO_DEVICE);

                ndev->stats.tx_packets++;
                ndev->stats.tx_bytes += priv->tx_skb[tx_tail]->len;

                dev_consume_skb_irq(priv->tx_skb[tx_tail]);
                priv->tx_skb[tx_tail] = NULL;

                tx_tail = TX_NEXT(tx_tail);
        }
        priv->tx_tail = tx_tail;
        if (netif_queue_stopped(ndev) &&
            moxart_tx_queue_space(ndev) >= TX_WAKE_THRESHOLD)
                netif_wake_queue(ndev);
}

static irqreturn_t moxart_mac_interrupt(int irq, void *dev_id)
{
        struct net_device *ndev = (struct net_device *)dev_id;
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);
        unsigned int ists = readl(priv->base + REG_INTERRUPT_STATUS);

        if (ists & XPKT_OK_INT_STS)
                moxart_tx_finished(ndev);

        if (ists & RPKT_FINISH) {
                if (napi_schedule_prep(&priv->napi)) {
                        priv->reg_imr &= ~RPKT_FINISH_M;
                        writel(priv->reg_imr, priv->base + REG_INTERRUPT_MASK);
                        __napi_schedule(&priv->napi);
                }
        }

        return IRQ_HANDLED;
}

static netdev_tx_t moxart_mac_start_xmit(struct sk_buff *skb,
                                         struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);
        void *desc;
        unsigned int len;
        unsigned int tx_head;
        u32 txdes1;
        netdev_tx_t ret = NETDEV_TX_BUSY;

        spin_lock_irq(&priv->txlock);

        tx_head = priv->tx_head;
        desc = priv->tx_desc_base + (TX_REG_DESC_SIZE * tx_head);

        if (moxart_tx_queue_space(ndev) == 1)
                netif_stop_queue(ndev);

        if (moxart_desc_read(desc + TX_REG_OFFSET_DESC0) & TX_DESC0_DMA_OWN) {
                net_dbg_ratelimited("no TX space for packet\n");
                ndev->stats.tx_dropped++;
                goto out_unlock;
        }
        rmb(); /* ensure data is only read that had TX_DESC0_DMA_OWN cleared */

        len = skb->len > TX_BUF_SIZE ? TX_BUF_SIZE : skb->len;

        priv->tx_mapping[tx_head] = dma_map_single(&priv->pdev->dev, skb->data,
                                                   len, DMA_TO_DEVICE);
        if (dma_mapping_error(&priv->pdev->dev, priv->tx_mapping[tx_head])) {
                netdev_err(ndev, "DMA mapping error\n");
                goto out_unlock;
        }

        priv->tx_len[tx_head] = len;
        priv->tx_skb[tx_head] = skb;

        moxart_desc_write(priv->tx_mapping[tx_head],
               desc + TX_REG_OFFSET_DESC2 + TX_DESC2_ADDRESS_PHYS);
        moxart_desc_write((uintptr_t)skb->data,
               desc + TX_REG_OFFSET_DESC2 + TX_DESC2_ADDRESS_VIRT);

        if (skb->len < ETH_ZLEN) {
                memset(&skb->data[skb->len],
                       0, ETH_ZLEN - skb->len);
                len = ETH_ZLEN;
        }

        dma_sync_single_for_device(&priv->pdev->dev, priv->tx_mapping[tx_head],
                                   priv->tx_buf_size, DMA_TO_DEVICE);

        txdes1 = TX_DESC1_LTS | TX_DESC1_FTS | (len & TX_DESC1_BUF_SIZE_MASK);
        if (tx_head == TX_DESC_NUM_MASK)
                txdes1 |= TX_DESC1_END;
        moxart_desc_write(txdes1, desc + TX_REG_OFFSET_DESC1);
        wmb(); /* flush descriptor before transferring ownership */
        moxart_desc_write(TX_DESC0_DMA_OWN, desc + TX_REG_OFFSET_DESC0);

        /* start to send packet */
        writel(0xffffffff, priv->base + REG_TX_POLL_DEMAND);

        priv->tx_head = TX_NEXT(tx_head);

        netif_trans_update(ndev);
        ret = NETDEV_TX_OK;
out_unlock:
        spin_unlock_irq(&priv->txlock);

        return ret;
}

static void moxart_mac_setmulticast(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);
        struct netdev_hw_addr *ha;
        int crc_val;

        netdev_for_each_mc_addr(ha, ndev) {
                crc_val = crc32_le(~0, ha->addr, ETH_ALEN);
                crc_val = (crc_val >> 26) & 0x3f;
                if (crc_val >= 32) {
                        writel(readl(priv->base + REG_MCAST_HASH_TABLE1) |
                               (1UL << (crc_val - 32)),
                               priv->base + REG_MCAST_HASH_TABLE1);
                } else {
                        writel(readl(priv->base + REG_MCAST_HASH_TABLE0) |
                               (1UL << crc_val),
                               priv->base + REG_MCAST_HASH_TABLE0);
                }
        }
}

static void moxart_mac_set_rx_mode(struct net_device *ndev)
{
        struct moxart_mac_priv_t *priv = netdev_priv(ndev);

        spin_lock_irq(&priv->txlock);

        (ndev->flags & IFF_PROMISC) ? (priv->reg_maccr |= RCV_ALL) :
                                      (priv->reg_maccr &= ~RCV_ALL);

        (ndev->flags & IFF_ALLMULTI) ? (priv->reg_maccr |= RX_MULTIPKT) :
                                       (priv->reg_maccr &= ~RX_MULTIPKT);

        if ((ndev->flags & IFF_MULTICAST) && netdev_mc_count(ndev)) {
                priv->reg_maccr |= HT_MULTI_EN;
                moxart_mac_setmulticast(ndev);
        } else {
                priv->reg_maccr &= ~HT_MULTI_EN;
        }

        writel(priv->reg_maccr, priv->base + REG_MAC_CTRL);

        spin_unlock_irq(&priv->txlock);
}

static const struct net_device_ops moxart_netdev_ops = {
        .ndo_open               = moxart_mac_open,
        .ndo_stop               = moxart_mac_stop,
        .ndo_start_xmit         = moxart_mac_start_xmit,
        .ndo_set_rx_mode        = moxart_mac_set_rx_mode,
        .ndo_set_mac_address    = moxart_set_mac_address,
        .ndo_validate_addr      = eth_validate_addr,
};

static int moxart_mac_probe(struct platform_device *pdev)
{
        struct device *p_dev = &pdev->dev;
        struct device_node *node = p_dev->of_node;
        struct net_device *ndev;
        struct moxart_mac_priv_t *priv;
        struct resource *res;
        unsigned int irq;
        int ret;

        ndev = alloc_etherdev(sizeof(struct moxart_mac_priv_t));
        if (!ndev)
                return -ENOMEM;

        irq = irq_of_parse_and_map(node, 0);
        if (irq <= 0) {
                netdev_err(ndev, "irq_of_parse_and_map failed\n");
                ret = -EINVAL;
                goto irq_map_fail;
        }

        priv = netdev_priv(ndev);
        priv->ndev = ndev;
        priv->pdev = pdev;

        priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(priv->base)) {
                ret = PTR_ERR(priv->base);
                goto init_fail;
        }
        ndev->base_addr = res->start;

        ret = platform_get_ethdev_address(p_dev, ndev);
        if (ret == -EPROBE_DEFER)
                goto init_fail;
        if (ret)
                eth_hw_addr_random(ndev);
        moxart_update_mac_address(ndev);

        spin_lock_init(&priv->txlock);

        priv->tx_buf_size = TX_BUF_SIZE;
        priv->rx_buf_size = RX_BUF_SIZE;

        priv->tx_desc_base = dma_alloc_coherent(p_dev, TX_REG_DESC_SIZE *
                                                TX_DESC_NUM, &priv->tx_base,
                                                GFP_DMA | GFP_KERNEL);
        if (!priv->tx_desc_base) {
                ret = -ENOMEM;
                goto init_fail;
        }

        priv->rx_desc_base = dma_alloc_coherent(p_dev, RX_REG_DESC_SIZE *
                                                RX_DESC_NUM, &priv->rx_base,
                                                GFP_DMA | GFP_KERNEL);
        if (!priv->rx_desc_base) {
                ret = -ENOMEM;
                goto init_fail;
        }

        priv->tx_buf_base = kmalloc_array(priv->tx_buf_size, TX_DESC_NUM,
                                          GFP_KERNEL);
        if (!priv->tx_buf_base) {
                ret = -ENOMEM;
                goto init_fail;
        }

        priv->rx_buf_base = kmalloc_array(priv->rx_buf_size, RX_DESC_NUM,
                                          GFP_KERNEL);
        if (!priv->rx_buf_base) {
                ret = -ENOMEM;
                goto init_fail;
        }

        platform_set_drvdata(pdev, ndev);

        ret = devm_request_irq(p_dev, irq, moxart_mac_interrupt, 0,
                               pdev->name, ndev);
        if (ret) {
                netdev_err(ndev, "devm_request_irq failed\n");
                goto init_fail;
        }

        ndev->netdev_ops = &moxart_netdev_ops;
        netif_napi_add_weight(ndev, &priv->napi, moxart_rx_poll, RX_DESC_NUM);
        ndev->priv_flags |= IFF_UNICAST_FLT;
        ndev->irq = irq;

        SET_NETDEV_DEV(ndev, &pdev->dev);

        ret = register_netdev(ndev);
        if (ret)
                goto init_fail;

        netdev_dbg(ndev, "%s: IRQ=%d address=%pM\n",
                   __func__, ndev->irq, ndev->dev_addr);

        return 0;

init_fail:
        netdev_err(ndev, "init failed\n");
        moxart_mac_free_memory(ndev);
irq_map_fail:
        free_netdev(ndev);
        return ret;
}

static void moxart_remove(struct platform_device *pdev)
{
        struct net_device *ndev = platform_get_drvdata(pdev);

        unregister_netdev(ndev);
        devm_free_irq(&pdev->dev, ndev->irq, ndev);
        moxart_mac_free_memory(ndev);
        free_netdev(ndev);
}

static const struct of_device_id moxart_mac_match[] = {
        { .compatible = "moxa,moxart-mac" },
        { }
};
MODULE_DEVICE_TABLE(of, moxart_mac_match);

static struct platform_driver moxart_mac_driver = {
        .probe  = moxart_mac_probe,
        .remove = moxart_remove,
        .driver = {
                .name           = "moxart-ethernet",
                .of_match_table = moxart_mac_match,
        },
};
module_platform_driver(moxart_mac_driver);

MODULE_DESCRIPTION("MOXART RTL8201CP Ethernet driver");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");