/*
 * Copyright(c) 2015 EZchip Technologies.
 *
 * 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.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 */

#include <linux/module.h>
#include <linux/etherdevice.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_net.h>
#include <linux/of_platform.h>
#include "nps_enet.h"

#define DRV_NAME                        "nps_mgt_enet"

static void nps_enet_clean_rx_fifo(struct net_device *ndev, u32 frame_len)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        u32 i, len = DIV_ROUND_UP(frame_len, sizeof(u32));

        /* Empty Rx FIFO buffer by reading all words */
        for (i = 0; i < len; i++)
                nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
}

static void nps_enet_read_rx_fifo(struct net_device *ndev,
                                  unsigned char *dst, u32 length)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        s32 i, last = length & (sizeof(u32) - 1);
        u32 *reg = (u32 *)dst, len = length / sizeof(u32);
        bool dst_is_aligned = IS_ALIGNED((unsigned long)dst, sizeof(u32));

        /* In case dst is not aligned we need an intermediate buffer */
        if (dst_is_aligned)
                for (i = 0; i < len; i++, reg++)
                        *reg = nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
        else { /* !dst_is_aligned */
                for (i = 0; i < len; i++, reg++) {
                        u32 buf = nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
                        put_unaligned(buf, reg);
                }
        }

        /* copy last bytes (if any) */
        if (last) {
                u32 buf = nps_enet_reg_get(priv, NPS_ENET_REG_RX_BUF);
                memcpy((u8*)reg, &buf, last);
        }
}

static u32 nps_enet_rx_handler(struct net_device *ndev)
{
        u32 frame_len, err = 0;
        u32 work_done = 0;
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct sk_buff *skb;
        struct nps_enet_rx_ctl rx_ctrl;

        rx_ctrl.value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
        frame_len = rx_ctrl.nr;

        /* Check if we got RX */
        if (!rx_ctrl.cr)
                return work_done;

        /* If we got here there is a work for us */
        work_done++;

        /* Check Rx error */
        if (rx_ctrl.er) {
                ndev->stats.rx_errors++;
                err = 1;
        }

        /* Check Rx CRC error */
        if (rx_ctrl.crc) {
                ndev->stats.rx_crc_errors++;
                ndev->stats.rx_dropped++;
                err = 1;
        }

        /* Check Frame length Min 64b */
        if (unlikely(frame_len < ETH_ZLEN)) {
                ndev->stats.rx_length_errors++;
                ndev->stats.rx_dropped++;
                err = 1;
        }

        if (err)
                goto rx_irq_clean;

        /* Skb allocation */
        skb = netdev_alloc_skb_ip_align(ndev, frame_len);
        if (unlikely(!skb)) {
                ndev->stats.rx_errors++;
                ndev->stats.rx_dropped++;
                goto rx_irq_clean;
        }

        /* Copy frame from Rx fifo into the skb */
        nps_enet_read_rx_fifo(ndev, skb->data, frame_len);

        skb_put(skb, frame_len);
        skb->protocol = eth_type_trans(skb, ndev);
        skb->ip_summed = CHECKSUM_UNNECESSARY;

        ndev->stats.rx_packets++;
        ndev->stats.rx_bytes += frame_len;
        netif_receive_skb(skb);

        goto rx_irq_frame_done;

rx_irq_clean:
        /* Clean Rx fifo */
        nps_enet_clean_rx_fifo(ndev, frame_len);

rx_irq_frame_done:
        /* Ack Rx ctrl register */
        nps_enet_reg_set(priv, NPS_ENET_REG_RX_CTL, 0);

        return work_done;
}

static void nps_enet_tx_handler(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_tx_ctl tx_ctrl;

        tx_ctrl.value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);

        /* Check if we got TX */
        if (!priv->tx_packet_sent || tx_ctrl.ct)
                return;

        /* Ack Tx ctrl register */
        nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, 0);

        /* Check Tx transmit error */
        if (unlikely(tx_ctrl.et)) {
                ndev->stats.tx_errors++;
        } else {
                ndev->stats.tx_packets++;
                ndev->stats.tx_bytes += tx_ctrl.nt;
        }

        dev_kfree_skb(priv->tx_skb);
        priv->tx_packet_sent = false;

        if (netif_queue_stopped(ndev))
                netif_wake_queue(ndev);
}

/**
 * nps_enet_poll - NAPI poll handler.
 * @napi:       Pointer to napi_struct structure.
 * @budget:     How many frames to process on one call.
 *
 * returns:     Number of processed frames
 */
static int nps_enet_poll(struct napi_struct *napi, int budget)
{
        struct net_device *ndev = napi->dev;
        struct nps_enet_priv *priv = netdev_priv(ndev);
        u32 work_done;

        nps_enet_tx_handler(ndev);
        work_done = nps_enet_rx_handler(ndev);
        if (work_done < budget) {
                struct nps_enet_buf_int_enable buf_int_enable;

                napi_complete(napi);
                buf_int_enable.rx_rdy = NPS_ENET_ENABLE;
                buf_int_enable.tx_done = NPS_ENET_ENABLE;
                nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
                                 buf_int_enable.value);
        }

        return work_done;
}

/**
 * nps_enet_irq_handler - Global interrupt handler for ENET.
 * @irq:                irq number.
 * @dev_instance:       device instance.
 *
 * returns: IRQ_HANDLED for all cases.
 *
 * EZchip ENET has 2 interrupt causes, and depending on bits raised in
 * CTRL registers we may tell what is a reason for interrupt to fire up.
 * We got one for RX and the other for TX (completion).
 */
static irqreturn_t nps_enet_irq_handler(s32 irq, void *dev_instance)
{
        struct net_device *ndev = dev_instance;
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_rx_ctl rx_ctrl;
        struct nps_enet_tx_ctl tx_ctrl;

        rx_ctrl.value = nps_enet_reg_get(priv, NPS_ENET_REG_RX_CTL);
        tx_ctrl.value = nps_enet_reg_get(priv, NPS_ENET_REG_TX_CTL);

        if ((!tx_ctrl.ct && priv->tx_packet_sent) || rx_ctrl.cr)
                if (likely(napi_schedule_prep(&priv->napi))) {
                        nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);
                        __napi_schedule(&priv->napi);
                }

        return IRQ_HANDLED;
}

static void nps_enet_set_hw_mac_address(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_ge_mac_cfg_1 ge_mac_cfg_1;
        struct nps_enet_ge_mac_cfg_2 *ge_mac_cfg_2 = &priv->ge_mac_cfg_2;

        /* set MAC address in HW */
        ge_mac_cfg_1.octet_0 = ndev->dev_addr[0];
        ge_mac_cfg_1.octet_1 = ndev->dev_addr[1];
        ge_mac_cfg_1.octet_2 = ndev->dev_addr[2];
        ge_mac_cfg_1.octet_3 = ndev->dev_addr[3];
        ge_mac_cfg_2->octet_4 = ndev->dev_addr[4];
        ge_mac_cfg_2->octet_5 = ndev->dev_addr[5];

        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_1,
                         ge_mac_cfg_1.value);

        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
                         ge_mac_cfg_2->value);
}

/**
 * nps_enet_hw_reset - Reset the network device.
 * @ndev:       Pointer to the network device.
 *
 * This function reset the PCS and TX fifo.
 * The programming model is to set the relevant reset bits
 * wait for some time for this to propagate and then unset
 * the reset bits. This way we ensure that reset procedure
 * is done successfully by device.
 */
static void nps_enet_hw_reset(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_ge_rst ge_rst;
        struct nps_enet_phase_fifo_ctl phase_fifo_ctl;

        ge_rst.value = 0;
        phase_fifo_ctl.value = 0;
        /* Pcs reset sequence*/
        ge_rst.gmac_0 = NPS_ENET_ENABLE;
        nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst.value);
        usleep_range(10, 20);
        ge_rst.value = 0;
        nps_enet_reg_set(priv, NPS_ENET_REG_GE_RST, ge_rst.value);

        /* Tx fifo reset sequence */
        phase_fifo_ctl.rst = NPS_ENET_ENABLE;
        phase_fifo_ctl.init = NPS_ENET_ENABLE;
        nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
                         phase_fifo_ctl.value);
        usleep_range(10, 20);
        phase_fifo_ctl.value = 0;
        nps_enet_reg_set(priv, NPS_ENET_REG_PHASE_FIFO_CTL,
                         phase_fifo_ctl.value);
}

static void nps_enet_hw_enable_control(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_ge_mac_cfg_0 ge_mac_cfg_0;
        struct nps_enet_buf_int_enable buf_int_enable;
        struct nps_enet_ge_mac_cfg_2 *ge_mac_cfg_2 = &priv->ge_mac_cfg_2;
        struct nps_enet_ge_mac_cfg_3 *ge_mac_cfg_3 = &priv->ge_mac_cfg_3;
        s32 max_frame_length;

        ge_mac_cfg_0.value = 0;
        buf_int_enable.value = 0;
        /* Enable Rx and Tx statistics */
        ge_mac_cfg_2->stat_en = NPS_ENET_GE_MAC_CFG_2_STAT_EN;

        /* Discard packets with different MAC address */
        ge_mac_cfg_2->disc_da = NPS_ENET_ENABLE;

        /* Discard multicast packets */
        ge_mac_cfg_2->disc_mc = NPS_ENET_ENABLE;

        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2,
                         ge_mac_cfg_2->value);

        /* Discard Packets bigger than max frame length */
        max_frame_length = ETH_HLEN + ndev->mtu + ETH_FCS_LEN;
        if (max_frame_length <= NPS_ENET_MAX_FRAME_LENGTH)
                ge_mac_cfg_3->max_len = max_frame_length;

        /* Enable interrupts */
        buf_int_enable.rx_rdy = NPS_ENET_ENABLE;
        buf_int_enable.tx_done = NPS_ENET_ENABLE;
        nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE,
                         buf_int_enable.value);

        /* Write device MAC address to HW */
        nps_enet_set_hw_mac_address(ndev);

        /* Rx and Tx HW features */
        ge_mac_cfg_0.tx_pad_en = NPS_ENET_ENABLE;
        ge_mac_cfg_0.tx_crc_en = NPS_ENET_ENABLE;
        ge_mac_cfg_0.rx_crc_strip = NPS_ENET_ENABLE;

        /* IFG configuration */
        ge_mac_cfg_0.rx_ifg = NPS_ENET_GE_MAC_CFG_0_RX_IFG;
        ge_mac_cfg_0.tx_ifg = NPS_ENET_GE_MAC_CFG_0_TX_IFG;

        /* preamble configuration */
        ge_mac_cfg_0.rx_pr_check_en = NPS_ENET_ENABLE;
        ge_mac_cfg_0.tx_pr_len = NPS_ENET_GE_MAC_CFG_0_TX_PR_LEN;

        /* enable flow control frames */
        ge_mac_cfg_0.tx_fc_en = NPS_ENET_ENABLE;
        ge_mac_cfg_0.rx_fc_en = NPS_ENET_ENABLE;
        ge_mac_cfg_0.tx_fc_retr = NPS_ENET_GE_MAC_CFG_0_TX_FC_RETR;
        ge_mac_cfg_3->cf_drop = NPS_ENET_ENABLE;

        /* Enable Rx and Tx */
        ge_mac_cfg_0.rx_en = NPS_ENET_ENABLE;
        ge_mac_cfg_0.tx_en = NPS_ENET_ENABLE;

        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_3,
                         ge_mac_cfg_3->value);
        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0,
                         ge_mac_cfg_0.value);
}

static void nps_enet_hw_disable_control(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);

        /* Disable interrupts */
        nps_enet_reg_set(priv, NPS_ENET_REG_BUF_INT_ENABLE, 0);

        /* Disable Rx and Tx */
        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_0, 0);
}

static void nps_enet_send_frame(struct net_device *ndev,
                                struct sk_buff *skb)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_tx_ctl tx_ctrl;
        short length = skb->len;
        u32 i, len = DIV_ROUND_UP(length, sizeof(u32));
        u32 *src = (void *)skb->data;
        bool src_is_aligned = IS_ALIGNED((unsigned long)src, sizeof(u32));

        tx_ctrl.value = 0;
        /* In case src is not aligned we need an intermediate buffer */
        if (src_is_aligned)
                for (i = 0; i < len; i++, src++)
                        nps_enet_reg_set(priv, NPS_ENET_REG_TX_BUF, *src);
        else /* !src_is_aligned */
                for (i = 0; i < len; i++, src++)
                        nps_enet_reg_set(priv, NPS_ENET_REG_TX_BUF,
                                         get_unaligned(src));

        /* Write the length of the Frame */
        tx_ctrl.nt = length;

        /* Indicate SW is done */
        priv->tx_packet_sent = true;
        tx_ctrl.ct = NPS_ENET_ENABLE;

        /* Send Frame */
        nps_enet_reg_set(priv, NPS_ENET_REG_TX_CTL, tx_ctrl.value);
}

/**
 * nps_enet_set_mac_address - Set the MAC address for this device.
 * @ndev:       Pointer to net_device structure.
 * @p:          6 byte Address to be written as MAC address.
 *
 * This function copies the HW address from the sockaddr structure to the
 * net_device structure and updates the address in HW.
 *
 * returns:     -EBUSY if the net device is busy or 0 if the address is set
 *              successfully.
 */
static s32 nps_enet_set_mac_address(struct net_device *ndev, void *p)
{
        struct sockaddr *addr = p;
        s32 res;

        if (netif_running(ndev))
                return -EBUSY;

        res = eth_mac_addr(ndev, p);
        if (!res) {
                ether_addr_copy(ndev->dev_addr, addr->sa_data);
                nps_enet_set_hw_mac_address(ndev);
        }

        return res;
}

/**
 * nps_enet_set_rx_mode - Change the receive filtering mode.
 * @ndev:       Pointer to the network device.
 *
 * This function enables/disables promiscuous mode
 */
static void nps_enet_set_rx_mode(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        struct nps_enet_ge_mac_cfg_2 ge_mac_cfg_2;

        ge_mac_cfg_2.value = priv->ge_mac_cfg_2.value;

        if (ndev->flags & IFF_PROMISC) {
                ge_mac_cfg_2.disc_da = NPS_ENET_DISABLE;
                ge_mac_cfg_2.disc_mc = NPS_ENET_DISABLE;
        } else {
                ge_mac_cfg_2.disc_da = NPS_ENET_ENABLE;
                ge_mac_cfg_2.disc_mc = NPS_ENET_ENABLE;
        }

        nps_enet_reg_set(priv, NPS_ENET_REG_GE_MAC_CFG_2, ge_mac_cfg_2.value);
}

/**
 * nps_enet_open - Open the network device.
 * @ndev:       Pointer to the network device.
 *
 * returns: 0, on success or non-zero error value on failure.
 *
 * This function sets the MAC address, requests and enables an IRQ
 * for the ENET device and starts the Tx queue.
 */
static s32 nps_enet_open(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);
        s32 err;

        /* Reset private variables */
        priv->tx_packet_sent = false;
        priv->ge_mac_cfg_2.value = 0;
        priv->ge_mac_cfg_3.value = 0;

        /* ge_mac_cfg_3 default values */
        priv->ge_mac_cfg_3.rx_ifg_th = NPS_ENET_GE_MAC_CFG_3_RX_IFG_TH;
        priv->ge_mac_cfg_3.max_len = NPS_ENET_GE_MAC_CFG_3_MAX_LEN;

        /* Disable HW device */
        nps_enet_hw_disable_control(ndev);

        /* irq Rx allocation */
        err = request_irq(priv->irq, nps_enet_irq_handler,
                          0, "enet-rx-tx", ndev);
        if (err)
                return err;

        napi_enable(&priv->napi);

        /* Enable HW device */
        nps_enet_hw_reset(ndev);
        nps_enet_hw_enable_control(ndev);

        netif_start_queue(ndev);

        return 0;
}

/**
 * nps_enet_stop - Close the network device.
 * @ndev:       Pointer to the network device.
 *
 * This function stops the Tx queue, disables interrupts for the ENET device.
 */
static s32 nps_enet_stop(struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);

        napi_disable(&priv->napi);
        netif_stop_queue(ndev);
        nps_enet_hw_disable_control(ndev);
        free_irq(priv->irq, ndev);

        return 0;
}

/**
 * nps_enet_start_xmit - Starts the data transmission.
 * @skb:        sk_buff pointer that contains data to be Transmitted.
 * @ndev:       Pointer to net_device structure.
 *
 * returns: NETDEV_TX_OK, on success
 *              NETDEV_TX_BUSY, if any of the descriptors are not free.
 *
 * This function is invoked from upper layers to initiate transmission.
 */
static netdev_tx_t nps_enet_start_xmit(struct sk_buff *skb,
                                       struct net_device *ndev)
{
        struct nps_enet_priv *priv = netdev_priv(ndev);

        /* This driver handles one frame at a time  */
        netif_stop_queue(ndev);

        priv->tx_skb = skb;

        nps_enet_send_frame(ndev, skb);

        return NETDEV_TX_OK;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void nps_enet_poll_controller(struct net_device *ndev)
{
        disable_irq(ndev->irq);
        nps_enet_irq_handler(ndev->irq, ndev);
        enable_irq(ndev->irq);
}
#endif

static const struct net_device_ops nps_netdev_ops = {
        .ndo_open               = nps_enet_open,
        .ndo_stop               = nps_enet_stop,
        .ndo_start_xmit         = nps_enet_start_xmit,
        .ndo_set_mac_address    = nps_enet_set_mac_address,
        .ndo_set_rx_mode        = nps_enet_set_rx_mode,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller    = nps_enet_poll_controller,
#endif
};

static s32 nps_enet_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct net_device *ndev;
        struct nps_enet_priv *priv;
        s32 err = 0;
        const char *mac_addr;
        struct resource *res_regs;

        if (!dev->of_node)
                return -ENODEV;

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

        platform_set_drvdata(pdev, ndev);
        SET_NETDEV_DEV(ndev, dev);
        priv = netdev_priv(ndev);

        /* The EZ NET specific entries in the device structure. */
        ndev->netdev_ops = &nps_netdev_ops;
        ndev->watchdog_timeo = (400 * HZ / 1000);
        /* FIXME :: no multicast support yet */
        ndev->flags &= ~IFF_MULTICAST;

        res_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        priv->regs_base = devm_ioremap_resource(dev, res_regs);
        if (IS_ERR(priv->regs_base)) {
                err = PTR_ERR(priv->regs_base);
                goto out_netdev;
        }
        dev_dbg(dev, "Registers base address is 0x%p\n", priv->regs_base);

        /* set kernel MAC address to dev */
        mac_addr = of_get_mac_address(dev->of_node);
        if (mac_addr)
                ether_addr_copy(ndev->dev_addr, mac_addr);
        else
                eth_hw_addr_random(ndev);

        /* Get IRQ number */
        priv->irq = platform_get_irq(pdev, 0);
        if (!priv->irq) {
                dev_err(dev, "failed to retrieve <irq Rx-Tx> value from device tree\n");
                err = -ENODEV;
                goto out_netdev;
        }

        netif_napi_add(ndev, &priv->napi, nps_enet_poll,
                       NPS_ENET_NAPI_POLL_WEIGHT);

        /* Register the driver. Should be the last thing in probe */
        err = register_netdev(ndev);
        if (err) {
                dev_err(dev, "Failed to register ndev for %s, err = 0x%08x\n",
                        ndev->name, (s32)err);
                goto out_netif_api;
        }

        dev_info(dev, "(rx/tx=%d)\n", priv->irq);
        return 0;

out_netif_api:
        netif_napi_del(&priv->napi);
out_netdev:
        if (err)
                free_netdev(ndev);

        return err;
}

static s32 nps_enet_remove(struct platform_device *pdev)
{
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct nps_enet_priv *priv = netdev_priv(ndev);

        unregister_netdev(ndev);
        free_netdev(ndev);
        netif_napi_del(&priv->napi);

        return 0;
}

static const struct of_device_id nps_enet_dt_ids[] = {
        { .compatible = "ezchip,nps-mgt-enet" },
        { /* Sentinel */ }
};

static struct platform_driver nps_enet_driver = {
        .probe = nps_enet_probe,
        .remove = nps_enet_remove,
        .driver = {
                .name = DRV_NAME,
                .of_match_table  = nps_enet_dt_ids,
        },
};

module_platform_driver(nps_enet_driver);

MODULE_AUTHOR("EZchip Semiconductor");
MODULE_LICENSE("GPL v2");