// SPDX-License-Identifier: GPL-2.0
/*
 * Lantiq / Intel PMAC driver for XRX200 SoCs
 *
 * Copyright (C) 2010 Lantiq Deutschland
 * Copyright (C) 2012 John Crispin <john@phrozen.org>
 * Copyright (C) 2017 - 2018 Hauke Mehrtens <hauke@hauke-m.de>
 */

#include <linux/etherdevice.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/delay.h>

#include <linux/if_vlan.h>

#include <linux/of_net.h>
#include <linux/of_platform.h>

#include <xway_dma.h>

/* DMA */
#define XRX200_DMA_DATA_LEN     (SZ_64K - 1)
#define XRX200_DMA_RX           0
#define XRX200_DMA_TX           1
#define XRX200_DMA_BURST_LEN    8

#define XRX200_DMA_PACKET_COMPLETE      0
#define XRX200_DMA_PACKET_IN_PROGRESS   1

/* cpu port mac */
#define PMAC_RX_IPG             0x0024
#define PMAC_RX_IPG_MASK        0xf

#define PMAC_HD_CTL             0x0000
/* Add Ethernet header to packets from DMA to PMAC */
#define PMAC_HD_CTL_ADD         BIT(0)
/* Add VLAN tag to Packets from DMA to PMAC */
#define PMAC_HD_CTL_TAG         BIT(1)
/* Add CRC to packets from DMA to PMAC */
#define PMAC_HD_CTL_AC          BIT(2)
/* Add status header to packets from PMAC to DMA */
#define PMAC_HD_CTL_AS          BIT(3)
/* Remove CRC from packets from PMAC to DMA */
#define PMAC_HD_CTL_RC          BIT(4)
/* Remove Layer-2 header from packets from PMAC to DMA */
#define PMAC_HD_CTL_RL2         BIT(5)
/* Status header is present from DMA to PMAC */
#define PMAC_HD_CTL_RXSH        BIT(6)
/* Add special tag from PMAC to switch */
#define PMAC_HD_CTL_AST         BIT(7)
/* Remove specail Tag from PMAC to DMA */
#define PMAC_HD_CTL_RST         BIT(8)
/* Check CRC from DMA to PMAC */
#define PMAC_HD_CTL_CCRC        BIT(9)
/* Enable reaction to Pause frames in the PMAC */
#define PMAC_HD_CTL_FC          BIT(10)

struct xrx200_chan {
        int tx_free;

        struct napi_struct napi;
        struct ltq_dma_channel dma;

        union {
                struct sk_buff *skb[LTQ_DESC_NUM];
                void *rx_buff[LTQ_DESC_NUM];
        };

        struct sk_buff *skb_head;
        struct sk_buff *skb_tail;

        struct xrx200_priv *priv;
};

struct xrx200_priv {
        struct clk *clk;

        struct xrx200_chan chan_tx;
        struct xrx200_chan chan_rx;

        u16 rx_buf_size;
        u16 rx_skb_size;

        struct net_device *net_dev;
        struct device *dev;

        __iomem void *pmac_reg;
};

static u32 xrx200_pmac_r32(struct xrx200_priv *priv, u32 offset)
{
        return __raw_readl(priv->pmac_reg + offset);
}

static void xrx200_pmac_w32(struct xrx200_priv *priv, u32 val, u32 offset)
{
        __raw_writel(val, priv->pmac_reg + offset);
}

static void xrx200_pmac_mask(struct xrx200_priv *priv, u32 clear, u32 set,
                             u32 offset)
{
        u32 val = xrx200_pmac_r32(priv, offset);

        val &= ~(clear);
        val |= set;
        xrx200_pmac_w32(priv, val, offset);
}

static int xrx200_max_frame_len(int mtu)
{
        return VLAN_ETH_HLEN + mtu;
}

static int xrx200_buffer_size(int mtu)
{
        return round_up(xrx200_max_frame_len(mtu), 4 * XRX200_DMA_BURST_LEN);
}

static int xrx200_skb_size(u16 buf_size)
{
        return SKB_DATA_ALIGN(buf_size + NET_SKB_PAD + NET_IP_ALIGN) +
                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
}

/* drop all the packets from the DMA ring */
static void xrx200_flush_dma(struct xrx200_chan *ch)
{
        int i;

        for (i = 0; i < LTQ_DESC_NUM; i++) {
                struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->dma.desc];

                if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) != LTQ_DMA_C)
                        break;

                desc->ctl = LTQ_DMA_OWN | LTQ_DMA_RX_OFFSET(NET_IP_ALIGN) |
                            ch->priv->rx_buf_size;
                ch->dma.desc++;
                ch->dma.desc %= LTQ_DESC_NUM;
        }
}

static int xrx200_open(struct net_device *net_dev)
{
        struct xrx200_priv *priv = netdev_priv(net_dev);

        napi_enable(&priv->chan_tx.napi);
        ltq_dma_open(&priv->chan_tx.dma);
        ltq_dma_enable_irq(&priv->chan_tx.dma);

        napi_enable(&priv->chan_rx.napi);
        ltq_dma_open(&priv->chan_rx.dma);
        /* The boot loader does not always deactivate the receiving of frames
         * on the ports and then some packets queue up in the PPE buffers.
         * They already passed the PMAC so they do not have the tags
         * configured here. Read the these packets here and drop them.
         * The HW should have written them into memory after 10us
         */
        usleep_range(20, 40);
        xrx200_flush_dma(&priv->chan_rx);
        ltq_dma_enable_irq(&priv->chan_rx.dma);

        netif_wake_queue(net_dev);

        return 0;
}

static int xrx200_close(struct net_device *net_dev)
{
        struct xrx200_priv *priv = netdev_priv(net_dev);

        netif_stop_queue(net_dev);

        napi_disable(&priv->chan_rx.napi);
        ltq_dma_close(&priv->chan_rx.dma);

        napi_disable(&priv->chan_tx.napi);
        ltq_dma_close(&priv->chan_tx.dma);

        return 0;
}

static int xrx200_alloc_buf(struct xrx200_chan *ch, void *(*alloc)(unsigned int size))
{
        void *buf = ch->rx_buff[ch->dma.desc];
        struct xrx200_priv *priv = ch->priv;
        dma_addr_t mapping;
        int ret = 0;

        ch->rx_buff[ch->dma.desc] = alloc(priv->rx_skb_size);
        if (!ch->rx_buff[ch->dma.desc]) {
                ch->rx_buff[ch->dma.desc] = buf;
                ret = -ENOMEM;
                goto skip;
        }

        mapping = dma_map_single(priv->dev, ch->rx_buff[ch->dma.desc],
                                 priv->rx_buf_size, DMA_FROM_DEVICE);
        if (unlikely(dma_mapping_error(priv->dev, mapping))) {
                skb_free_frag(ch->rx_buff[ch->dma.desc]);
                ch->rx_buff[ch->dma.desc] = buf;
                ret = -ENOMEM;
                goto skip;
        }

        ch->dma.desc_base[ch->dma.desc].addr = mapping + NET_SKB_PAD + NET_IP_ALIGN;
        /* Make sure the address is written before we give it to HW */
        wmb();
skip:
        ch->dma.desc_base[ch->dma.desc].ctl =
                LTQ_DMA_OWN | LTQ_DMA_RX_OFFSET(NET_IP_ALIGN) | priv->rx_buf_size;

        return ret;
}

static int xrx200_hw_receive(struct xrx200_chan *ch)
{
        struct xrx200_priv *priv = ch->priv;
        struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->dma.desc];
        void *buf = ch->rx_buff[ch->dma.desc];
        u32 ctl = desc->ctl;
        int len = (ctl & LTQ_DMA_SIZE_MASK);
        struct net_device *net_dev = priv->net_dev;
        struct sk_buff *skb;
        int ret;

        ret = xrx200_alloc_buf(ch, napi_alloc_frag);

        ch->dma.desc++;
        ch->dma.desc %= LTQ_DESC_NUM;

        if (ret) {
                net_dev->stats.rx_dropped++;
                netdev_err(net_dev, "failed to allocate new rx buffer\n");
                return ret;
        }

        skb = build_skb(buf, priv->rx_skb_size);
        if (!skb) {
                skb_free_frag(buf);
                net_dev->stats.rx_dropped++;
                return -ENOMEM;
        }

        skb_reserve(skb, NET_SKB_PAD);
        skb_put(skb, len);

        /* add buffers to skb via skb->frag_list */
        if (ctl & LTQ_DMA_SOP) {
                ch->skb_head = skb;
                ch->skb_tail = skb;
                skb_reserve(skb, NET_IP_ALIGN);
        } else if (ch->skb_head) {
                if (ch->skb_head == ch->skb_tail)
                        skb_shinfo(ch->skb_tail)->frag_list = skb;
                else
                        ch->skb_tail->next = skb;
                ch->skb_tail = skb;
                ch->skb_head->len += skb->len;
                ch->skb_head->data_len += skb->len;
                ch->skb_head->truesize += skb->truesize;
        }

        if (ctl & LTQ_DMA_EOP) {
                ch->skb_head->protocol = eth_type_trans(ch->skb_head, net_dev);
                net_dev->stats.rx_packets++;
                net_dev->stats.rx_bytes += ch->skb_head->len;
                netif_receive_skb(ch->skb_head);
                ch->skb_head = NULL;
                ch->skb_tail = NULL;
                ret = XRX200_DMA_PACKET_COMPLETE;
        } else {
                ret = XRX200_DMA_PACKET_IN_PROGRESS;
        }

        return ret;
}

static int xrx200_poll_rx(struct napi_struct *napi, int budget)
{
        struct xrx200_chan *ch = container_of(napi,
                                struct xrx200_chan, napi);
        int rx = 0;
        int ret;

        while (rx < budget) {
                struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->dma.desc];

                if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) == LTQ_DMA_C) {
                        ret = xrx200_hw_receive(ch);
                        if (ret == XRX200_DMA_PACKET_IN_PROGRESS)
                                continue;
                        if (ret != XRX200_DMA_PACKET_COMPLETE)
                                break;
                        rx++;
                } else {
                        break;
                }
        }

        if (rx < budget) {
                if (napi_complete_done(&ch->napi, rx))
                        ltq_dma_enable_irq(&ch->dma);
        }

        return rx;
}

static int xrx200_tx_housekeeping(struct napi_struct *napi, int budget)
{
        struct xrx200_chan *ch = container_of(napi,
                                struct xrx200_chan, napi);
        struct net_device *net_dev = ch->priv->net_dev;
        int pkts = 0;
        int bytes = 0;

        netif_tx_lock(net_dev);
        while (pkts < budget) {
                struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->tx_free];

                if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) == LTQ_DMA_C) {
                        struct sk_buff *skb = ch->skb[ch->tx_free];

                        pkts++;
                        bytes += skb->len;
                        ch->skb[ch->tx_free] = NULL;
                        consume_skb(skb);
                        memset(&ch->dma.desc_base[ch->tx_free], 0,
                               sizeof(struct ltq_dma_desc));
                        ch->tx_free++;
                        ch->tx_free %= LTQ_DESC_NUM;
                } else {
                        break;
                }
        }

        net_dev->stats.tx_packets += pkts;
        net_dev->stats.tx_bytes += bytes;
        netdev_completed_queue(ch->priv->net_dev, pkts, bytes);

        netif_tx_unlock(net_dev);
        if (netif_queue_stopped(net_dev))
                netif_wake_queue(net_dev);

        if (pkts < budget) {
                if (napi_complete_done(&ch->napi, pkts))
                        ltq_dma_enable_irq(&ch->dma);
        }

        return pkts;
}

static netdev_tx_t xrx200_start_xmit(struct sk_buff *skb,
                                     struct net_device *net_dev)
{
        struct xrx200_priv *priv = netdev_priv(net_dev);
        struct xrx200_chan *ch = &priv->chan_tx;
        struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->dma.desc];
        u32 byte_offset;
        dma_addr_t mapping;
        int len;

        skb->dev = net_dev;
        if (skb_put_padto(skb, ETH_ZLEN)) {
                net_dev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        len = skb->len;

        if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) || ch->skb[ch->dma.desc]) {
                netdev_err(net_dev, "tx ring full\n");
                netif_stop_queue(net_dev);
                return NETDEV_TX_BUSY;
        }

        ch->skb[ch->dma.desc] = skb;

        mapping = dma_map_single(priv->dev, skb->data, len, DMA_TO_DEVICE);
        if (unlikely(dma_mapping_error(priv->dev, mapping)))
                goto err_drop;

        /* dma needs to start on a burst length value aligned address */
        byte_offset = mapping % (XRX200_DMA_BURST_LEN * 4);

        desc->addr = mapping - byte_offset;
        /* Make sure the address is written before we give it to HW */
        wmb();
        desc->ctl = LTQ_DMA_OWN | LTQ_DMA_SOP | LTQ_DMA_EOP |
                LTQ_DMA_TX_OFFSET(byte_offset) | (len & LTQ_DMA_SIZE_MASK);
        ch->dma.desc++;
        ch->dma.desc %= LTQ_DESC_NUM;
        if (ch->dma.desc == ch->tx_free)
                netif_stop_queue(net_dev);

        netdev_sent_queue(net_dev, len);

        return NETDEV_TX_OK;

err_drop:
        dev_kfree_skb(skb);
        net_dev->stats.tx_dropped++;
        net_dev->stats.tx_errors++;
        return NETDEV_TX_OK;
}

static int
xrx200_change_mtu(struct net_device *net_dev, int new_mtu)
{
        struct xrx200_priv *priv = netdev_priv(net_dev);
        struct xrx200_chan *ch_rx = &priv->chan_rx;
        int old_mtu = net_dev->mtu;
        bool running = false;
        void *buff;
        int curr_desc;
        int ret = 0;

        WRITE_ONCE(net_dev->mtu, new_mtu);
        priv->rx_buf_size = xrx200_buffer_size(new_mtu);
        priv->rx_skb_size = xrx200_skb_size(priv->rx_buf_size);

        if (new_mtu <= old_mtu)
                return ret;

        running = netif_running(net_dev);
        if (running) {
                napi_disable(&ch_rx->napi);
                ltq_dma_close(&ch_rx->dma);
        }

        xrx200_poll_rx(&ch_rx->napi, LTQ_DESC_NUM);
        curr_desc = ch_rx->dma.desc;

        for (ch_rx->dma.desc = 0; ch_rx->dma.desc < LTQ_DESC_NUM;
             ch_rx->dma.desc++) {
                buff = ch_rx->rx_buff[ch_rx->dma.desc];
                ret = xrx200_alloc_buf(ch_rx, netdev_alloc_frag);
                if (ret) {
                        WRITE_ONCE(net_dev->mtu, old_mtu);
                        priv->rx_buf_size = xrx200_buffer_size(old_mtu);
                        priv->rx_skb_size = xrx200_skb_size(priv->rx_buf_size);
                        break;
                }
                skb_free_frag(buff);
        }

        ch_rx->dma.desc = curr_desc;
        if (running) {
                napi_enable(&ch_rx->napi);
                ltq_dma_open(&ch_rx->dma);
                ltq_dma_enable_irq(&ch_rx->dma);
        }

        return ret;
}

static const struct net_device_ops xrx200_netdev_ops = {
        .ndo_open               = xrx200_open,
        .ndo_stop               = xrx200_close,
        .ndo_start_xmit         = xrx200_start_xmit,
        .ndo_change_mtu         = xrx200_change_mtu,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};

static irqreturn_t xrx200_dma_irq(int irq, void *ptr)
{
        struct xrx200_chan *ch = ptr;

        if (napi_schedule_prep(&ch->napi)) {
                ltq_dma_disable_irq(&ch->dma);
                __napi_schedule(&ch->napi);
        }

        ltq_dma_ack_irq(&ch->dma);

        return IRQ_HANDLED;
}

static int xrx200_dma_init(struct xrx200_priv *priv)
{
        struct xrx200_chan *ch_rx = &priv->chan_rx;
        struct xrx200_chan *ch_tx = &priv->chan_tx;
        int ret = 0;
        int i;

        ltq_dma_init_port(DMA_PORT_ETOP, XRX200_DMA_BURST_LEN,
                          XRX200_DMA_BURST_LEN);

        ch_rx->dma.nr = XRX200_DMA_RX;
        ch_rx->dma.dev = priv->dev;
        ch_rx->priv = priv;

        ltq_dma_alloc_rx(&ch_rx->dma);
        for (ch_rx->dma.desc = 0; ch_rx->dma.desc < LTQ_DESC_NUM;
             ch_rx->dma.desc++) {
                ret = xrx200_alloc_buf(ch_rx, netdev_alloc_frag);
                if (ret)
                        goto rx_free;
        }
        ch_rx->dma.desc = 0;
        ret = devm_request_irq(priv->dev, ch_rx->dma.irq, xrx200_dma_irq, 0,
                               "xrx200_net_rx", &priv->chan_rx);
        if (ret) {
                dev_err(priv->dev, "failed to request RX irq %d\n",
                        ch_rx->dma.irq);
                goto rx_ring_free;
        }

        ch_tx->dma.nr = XRX200_DMA_TX;
        ch_tx->dma.dev = priv->dev;
        ch_tx->priv = priv;

        ltq_dma_alloc_tx(&ch_tx->dma);
        ret = devm_request_irq(priv->dev, ch_tx->dma.irq, xrx200_dma_irq, 0,
                               "xrx200_net_tx", &priv->chan_tx);
        if (ret) {
                dev_err(priv->dev, "failed to request TX irq %d\n",
                        ch_tx->dma.irq);
                goto tx_free;
        }

        return ret;

tx_free:
        ltq_dma_free(&ch_tx->dma);

rx_ring_free:
        /* free the allocated RX ring */
        for (i = 0; i < LTQ_DESC_NUM; i++) {
                if (priv->chan_rx.skb[i])
                        skb_free_frag(priv->chan_rx.rx_buff[i]);
        }

rx_free:
        ltq_dma_free(&ch_rx->dma);
        return ret;
}

static void xrx200_hw_cleanup(struct xrx200_priv *priv)
{
        int i;

        ltq_dma_free(&priv->chan_tx.dma);
        ltq_dma_free(&priv->chan_rx.dma);

        /* free the allocated RX ring */
        for (i = 0; i < LTQ_DESC_NUM; i++)
                skb_free_frag(priv->chan_rx.rx_buff[i]);
}

static int xrx200_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct xrx200_priv *priv;
        struct net_device *net_dev;
        int err;

        /* alloc the network device */
        net_dev = devm_alloc_etherdev(dev, sizeof(struct xrx200_priv));
        if (!net_dev)
                return -ENOMEM;

        priv = netdev_priv(net_dev);
        priv->net_dev = net_dev;
        priv->dev = dev;

        net_dev->netdev_ops = &xrx200_netdev_ops;
        SET_NETDEV_DEV(net_dev, dev);
        net_dev->min_mtu = ETH_ZLEN;
        net_dev->max_mtu = XRX200_DMA_DATA_LEN - xrx200_max_frame_len(0);
        priv->rx_buf_size = xrx200_buffer_size(ETH_DATA_LEN);
        priv->rx_skb_size = xrx200_skb_size(priv->rx_buf_size);

        /* load the memory ranges */
        priv->pmac_reg = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
        if (IS_ERR(priv->pmac_reg))
                return PTR_ERR(priv->pmac_reg);

        priv->chan_rx.dma.irq = platform_get_irq_byname(pdev, "rx");
        if (priv->chan_rx.dma.irq < 0)
                return -ENOENT;
        priv->chan_tx.dma.irq = platform_get_irq_byname(pdev, "tx");
        if (priv->chan_tx.dma.irq < 0)
                return -ENOENT;

        /* get the clock */
        priv->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(priv->clk)) {
                dev_err(dev, "failed to get clock\n");
                return PTR_ERR(priv->clk);
        }

        err = of_get_ethdev_address(np, net_dev);
        if (err)
                eth_hw_addr_random(net_dev);

        /* bring up the dma engine and IP core */
        err = xrx200_dma_init(priv);
        if (err)
                return err;

        /* enable clock gate */
        err = clk_prepare_enable(priv->clk);
        if (err)
                goto err_uninit_dma;

        /* set IPG to 12 */
        xrx200_pmac_mask(priv, PMAC_RX_IPG_MASK, 0xb, PMAC_RX_IPG);

        /* enable status header, enable CRC */
        xrx200_pmac_mask(priv, 0,
                         PMAC_HD_CTL_RST | PMAC_HD_CTL_AST | PMAC_HD_CTL_RXSH |
                         PMAC_HD_CTL_AS | PMAC_HD_CTL_AC | PMAC_HD_CTL_RC,
                         PMAC_HD_CTL);

        /* setup NAPI */
        netif_napi_add(net_dev, &priv->chan_rx.napi, xrx200_poll_rx);
        netif_napi_add_tx(net_dev, &priv->chan_tx.napi,
                          xrx200_tx_housekeeping);

        platform_set_drvdata(pdev, priv);

        err = register_netdev(net_dev);
        if (err)
                goto err_unprepare_clk;

        return 0;

err_unprepare_clk:
        clk_disable_unprepare(priv->clk);

err_uninit_dma:
        xrx200_hw_cleanup(priv);

        return err;
}

static void xrx200_remove(struct platform_device *pdev)
{
        struct xrx200_priv *priv = platform_get_drvdata(pdev);
        struct net_device *net_dev = priv->net_dev;

        /* free stack related instances */
        netif_stop_queue(net_dev);
        netif_napi_del(&priv->chan_tx.napi);
        netif_napi_del(&priv->chan_rx.napi);

        /* remove the actual device */
        unregister_netdev(net_dev);

        /* release the clock */
        clk_disable_unprepare(priv->clk);

        /* shut down hardware */
        xrx200_hw_cleanup(priv);
}

static const struct of_device_id xrx200_match[] = {
        { .compatible = "lantiq,xrx200-net" },
        {},
};
MODULE_DEVICE_TABLE(of, xrx200_match);

static struct platform_driver xrx200_driver = {
        .probe = xrx200_probe,
        .remove = xrx200_remove,
        .driver = {
                .name = "lantiq,xrx200-net",
                .of_match_table = xrx200_match,
        },
};

module_platform_driver(xrx200_driver);

MODULE_AUTHOR("John Crispin <john@phrozen.org>");
MODULE_DESCRIPTION("Lantiq SoC XRX200 ethernet");
MODULE_LICENSE("GPL");