// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Faraday FTGMAC100 Gigabit Ethernet
 *
 * (C) Copyright 2009-2011 Faraday Technology
 * Po-Yu Chuang <ratbert@faraday-tech.com>
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/of.h>
#include <linux/of_mdio.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/crc32.h>
#include <linux/if_vlan.h>
#include <linux/of_net.h>
#include <net/ip.h>
#include <net/ncsi.h>

#include "ftgmac100.h"

#define DRV_NAME        "ftgmac100"

/* Arbitrary values, I am not sure the HW has limits */
#define MAX_RX_QUEUE_ENTRIES    1024
#define MAX_TX_QUEUE_ENTRIES    1024
#define MIN_RX_QUEUE_ENTRIES    32
#define MIN_TX_QUEUE_ENTRIES    32

/* Defaults */
#define DEF_RX_QUEUE_ENTRIES    128
#define DEF_TX_QUEUE_ENTRIES    128

#define MAX_PKT_SIZE            1536
#define RX_BUF_SIZE             MAX_PKT_SIZE    /* must be smaller than 0x3fff */

/* Min number of tx ring entries before stopping queue */
#define TX_THRESHOLD            (MAX_SKB_FRAGS + 1)

#define FTGMAC_100MHZ           100000000
#define FTGMAC_25MHZ            25000000

struct ftgmac100 {
        /* Registers */
        struct resource *res;
        void __iomem *base;

        /* Rx ring */
        unsigned int rx_q_entries;
        struct ftgmac100_rxdes *rxdes;
        dma_addr_t rxdes_dma;
        struct sk_buff **rx_skbs;
        unsigned int rx_pointer;
        u32 rxdes0_edorr_mask;

        /* Tx ring */
        unsigned int tx_q_entries;
        struct ftgmac100_txdes *txdes;
        dma_addr_t txdes_dma;
        struct sk_buff **tx_skbs;
        unsigned int tx_clean_pointer;
        unsigned int tx_pointer;
        u32 txdes0_edotr_mask;

        /* Used to signal the reset task of ring change request */
        unsigned int new_rx_q_entries;
        unsigned int new_tx_q_entries;

        /* Scratch page to use when rx skb alloc fails */
        void *rx_scratch;
        dma_addr_t rx_scratch_dma;

        /* Component structures */
        struct net_device *netdev;
        struct device *dev;
        struct ncsi_dev *ndev;
        struct napi_struct napi;
        struct work_struct reset_task;
        struct mii_bus *mii_bus;
        struct clk *clk;

        /* AST2500/AST2600 RMII ref clock gate */
        struct clk *rclk;

        /* Link management */
        int cur_speed;
        int cur_duplex;
        bool use_ncsi;

        /* Multicast filter settings */
        u32 maht0;
        u32 maht1;

        /* Flow control settings */
        bool tx_pause;
        bool rx_pause;
        bool aneg_pause;

        /* Misc */
        bool need_mac_restart;
        bool is_aspeed;
};

static int ftgmac100_reset_mac(struct ftgmac100 *priv, u32 maccr)
{
        struct net_device *netdev = priv->netdev;
        int i;

        /* NOTE: reset clears all registers */
        iowrite32(maccr, priv->base + FTGMAC100_OFFSET_MACCR);
        iowrite32(maccr | FTGMAC100_MACCR_SW_RST,
                  priv->base + FTGMAC100_OFFSET_MACCR);
        for (i = 0; i < 200; i++) {
                unsigned int maccr;

                maccr = ioread32(priv->base + FTGMAC100_OFFSET_MACCR);
                if (!(maccr & FTGMAC100_MACCR_SW_RST))
                        return 0;

                udelay(1);
        }

        netdev_err(netdev, "Hardware reset failed\n");
        return -EIO;
}

static int ftgmac100_reset_and_config_mac(struct ftgmac100 *priv)
{
        u32 maccr = 0;

        switch (priv->cur_speed) {
        case SPEED_10:
        case 0: /* no link */
                break;

        case SPEED_100:
                maccr |= FTGMAC100_MACCR_FAST_MODE;
                break;

        case SPEED_1000:
                maccr |= FTGMAC100_MACCR_GIGA_MODE;
                break;
        default:
                netdev_err(priv->netdev, "Unknown speed %d !\n",
                           priv->cur_speed);
                break;
        }

        /* (Re)initialize the queue pointers */
        priv->rx_pointer = 0;
        priv->tx_clean_pointer = 0;
        priv->tx_pointer = 0;

        /* The doc says reset twice with 10us interval */
        if (ftgmac100_reset_mac(priv, maccr))
                return -EIO;
        usleep_range(10, 1000);
        return ftgmac100_reset_mac(priv, maccr);
}

static void ftgmac100_write_mac_addr(struct ftgmac100 *priv, const u8 *mac)
{
        unsigned int maddr = mac[0] << 8 | mac[1];
        unsigned int laddr = mac[2] << 24 | mac[3] << 16 | mac[4] << 8 | mac[5];

        iowrite32(maddr, priv->base + FTGMAC100_OFFSET_MAC_MADR);
        iowrite32(laddr, priv->base + FTGMAC100_OFFSET_MAC_LADR);
}

static void ftgmac100_initial_mac(struct ftgmac100 *priv)
{
        u8 mac[ETH_ALEN];
        unsigned int m;
        unsigned int l;
        void *addr;

        addr = device_get_mac_address(priv->dev, mac, ETH_ALEN);
        if (addr) {
                ether_addr_copy(priv->netdev->dev_addr, mac);
                dev_info(priv->dev, "Read MAC address %pM from device tree\n",
                         mac);
                return;
        }

        m = ioread32(priv->base + FTGMAC100_OFFSET_MAC_MADR);
        l = ioread32(priv->base + FTGMAC100_OFFSET_MAC_LADR);

        mac[0] = (m >> 8) & 0xff;
        mac[1] = m & 0xff;
        mac[2] = (l >> 24) & 0xff;
        mac[3] = (l >> 16) & 0xff;
        mac[4] = (l >> 8) & 0xff;
        mac[5] = l & 0xff;

        if (is_valid_ether_addr(mac)) {
                ether_addr_copy(priv->netdev->dev_addr, mac);
                dev_info(priv->dev, "Read MAC address %pM from chip\n", mac);
        } else {
                eth_hw_addr_random(priv->netdev);
                dev_info(priv->dev, "Generated random MAC address %pM\n",
                         priv->netdev->dev_addr);
        }
}

static int ftgmac100_set_mac_addr(struct net_device *dev, void *p)
{
        int ret;

        ret = eth_prepare_mac_addr_change(dev, p);
        if (ret < 0)
                return ret;

        eth_commit_mac_addr_change(dev, p);
        ftgmac100_write_mac_addr(netdev_priv(dev), dev->dev_addr);

        return 0;
}

static void ftgmac100_config_pause(struct ftgmac100 *priv)
{
        u32 fcr = FTGMAC100_FCR_PAUSE_TIME(16);

        /* Throttle tx queue when receiving pause frames */
        if (priv->rx_pause)
                fcr |= FTGMAC100_FCR_FC_EN;

        /* Enables sending pause frames when the RX queue is past a
         * certain threshold.
         */
        if (priv->tx_pause)
                fcr |= FTGMAC100_FCR_FCTHR_EN;

        iowrite32(fcr, priv->base + FTGMAC100_OFFSET_FCR);
}

static void ftgmac100_init_hw(struct ftgmac100 *priv)
{
        u32 reg, rfifo_sz, tfifo_sz;

        /* Clear stale interrupts */
        reg = ioread32(priv->base + FTGMAC100_OFFSET_ISR);
        iowrite32(reg, priv->base + FTGMAC100_OFFSET_ISR);

        /* Setup RX ring buffer base */
        iowrite32(priv->rxdes_dma, priv->base + FTGMAC100_OFFSET_RXR_BADR);

        /* Setup TX ring buffer base */
        iowrite32(priv->txdes_dma, priv->base + FTGMAC100_OFFSET_NPTXR_BADR);

        /* Configure RX buffer size */
        iowrite32(FTGMAC100_RBSR_SIZE(RX_BUF_SIZE),
                  priv->base + FTGMAC100_OFFSET_RBSR);

        /* Set RX descriptor autopoll */
        iowrite32(FTGMAC100_APTC_RXPOLL_CNT(1),
                  priv->base + FTGMAC100_OFFSET_APTC);

        /* Write MAC address */
        ftgmac100_write_mac_addr(priv, priv->netdev->dev_addr);

        /* Write multicast filter */
        iowrite32(priv->maht0, priv->base + FTGMAC100_OFFSET_MAHT0);
        iowrite32(priv->maht1, priv->base + FTGMAC100_OFFSET_MAHT1);

        /* Configure descriptor sizes and increase burst sizes according
         * to values in Aspeed SDK. The FIFO arbitration is enabled and
         * the thresholds set based on the recommended values in the
         * AST2400 specification.
         */
        iowrite32(FTGMAC100_DBLAC_RXDES_SIZE(2) |   /* 2*8 bytes RX descs */
                  FTGMAC100_DBLAC_TXDES_SIZE(2) |   /* 2*8 bytes TX descs */
                  FTGMAC100_DBLAC_RXBURST_SIZE(3) | /* 512 bytes max RX bursts */
                  FTGMAC100_DBLAC_TXBURST_SIZE(3) | /* 512 bytes max TX bursts */
                  FTGMAC100_DBLAC_RX_THR_EN |       /* Enable fifo threshold arb */
                  FTGMAC100_DBLAC_RXFIFO_HTHR(6) |  /* 6/8 of FIFO high threshold */
                  FTGMAC100_DBLAC_RXFIFO_LTHR(2),   /* 2/8 of FIFO low threshold */
                  priv->base + FTGMAC100_OFFSET_DBLAC);

        /* Interrupt mitigation configured for 1 interrupt/packet. HW interrupt
         * mitigation doesn't seem to provide any benefit with NAPI so leave
         * it at that.
         */
        iowrite32(FTGMAC100_ITC_RXINT_THR(1) |
                  FTGMAC100_ITC_TXINT_THR(1),
                  priv->base + FTGMAC100_OFFSET_ITC);

        /* Configure FIFO sizes in the TPAFCR register */
        reg = ioread32(priv->base + FTGMAC100_OFFSET_FEAR);
        rfifo_sz = reg & 0x00000007;
        tfifo_sz = (reg >> 3) & 0x00000007;
        reg = ioread32(priv->base + FTGMAC100_OFFSET_TPAFCR);
        reg &= ~0x3f000000;
        reg |= (tfifo_sz << 27);
        reg |= (rfifo_sz << 24);
        iowrite32(reg, priv->base + FTGMAC100_OFFSET_TPAFCR);
}

static void ftgmac100_start_hw(struct ftgmac100 *priv)
{
        u32 maccr = ioread32(priv->base + FTGMAC100_OFFSET_MACCR);

        /* Keep the original GMAC and FAST bits */
        maccr &= (FTGMAC100_MACCR_FAST_MODE | FTGMAC100_MACCR_GIGA_MODE);

        /* Add all the main enable bits */
        maccr |= FTGMAC100_MACCR_TXDMA_EN       |
                 FTGMAC100_MACCR_RXDMA_EN       |
                 FTGMAC100_MACCR_TXMAC_EN       |
                 FTGMAC100_MACCR_RXMAC_EN       |
                 FTGMAC100_MACCR_CRC_APD        |
                 FTGMAC100_MACCR_PHY_LINK_LEVEL |
                 FTGMAC100_MACCR_RX_RUNT        |
                 FTGMAC100_MACCR_RX_BROADPKT;

        /* Add other bits as needed */
        if (priv->cur_duplex == DUPLEX_FULL)
                maccr |= FTGMAC100_MACCR_FULLDUP;
        if (priv->netdev->flags & IFF_PROMISC)
                maccr |= FTGMAC100_MACCR_RX_ALL;
        if (priv->netdev->flags & IFF_ALLMULTI)
                maccr |= FTGMAC100_MACCR_RX_MULTIPKT;
        else if (netdev_mc_count(priv->netdev))
                maccr |= FTGMAC100_MACCR_HT_MULTI_EN;

        /* Vlan filtering enabled */
        if (priv->netdev->features & NETIF_F_HW_VLAN_CTAG_RX)
                maccr |= FTGMAC100_MACCR_RM_VLAN;

        /* Hit the HW */
        iowrite32(maccr, priv->base + FTGMAC100_OFFSET_MACCR);
}

static void ftgmac100_stop_hw(struct ftgmac100 *priv)
{
        iowrite32(0, priv->base + FTGMAC100_OFFSET_MACCR);
}

static void ftgmac100_calc_mc_hash(struct ftgmac100 *priv)
{
        struct netdev_hw_addr *ha;

        priv->maht1 = 0;
        priv->maht0 = 0;
        netdev_for_each_mc_addr(ha, priv->netdev) {
                u32 crc_val = ether_crc_le(ETH_ALEN, ha->addr);

                crc_val = (~(crc_val >> 2)) & 0x3f;
                if (crc_val >= 32)
                        priv->maht1 |= 1ul << (crc_val - 32);
                else
                        priv->maht0 |= 1ul << (crc_val);
        }
}

static void ftgmac100_set_rx_mode(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        /* Setup the hash filter */
        ftgmac100_calc_mc_hash(priv);

        /* Interface down ? that's all there is to do */
        if (!netif_running(netdev))
                return;

        /* Update the HW */
        iowrite32(priv->maht0, priv->base + FTGMAC100_OFFSET_MAHT0);
        iowrite32(priv->maht1, priv->base + FTGMAC100_OFFSET_MAHT1);

        /* Reconfigure MACCR */
        ftgmac100_start_hw(priv);
}

static int ftgmac100_alloc_rx_buf(struct ftgmac100 *priv, unsigned int entry,
                                  struct ftgmac100_rxdes *rxdes, gfp_t gfp)
{
        struct net_device *netdev = priv->netdev;
        struct sk_buff *skb;
        dma_addr_t map;
        int err = 0;

        skb = netdev_alloc_skb_ip_align(netdev, RX_BUF_SIZE);
        if (unlikely(!skb)) {
                if (net_ratelimit())
                        netdev_warn(netdev, "failed to allocate rx skb\n");
                err = -ENOMEM;
                map = priv->rx_scratch_dma;
        } else {
                map = dma_map_single(priv->dev, skb->data, RX_BUF_SIZE,
                                     DMA_FROM_DEVICE);
                if (unlikely(dma_mapping_error(priv->dev, map))) {
                        if (net_ratelimit())
                                netdev_err(netdev, "failed to map rx page\n");
                        dev_kfree_skb_any(skb);
                        map = priv->rx_scratch_dma;
                        skb = NULL;
                        err = -ENOMEM;
                }
        }

        /* Store skb */
        priv->rx_skbs[entry] = skb;

        /* Store DMA address into RX desc */
        rxdes->rxdes3 = cpu_to_le32(map);

        /* Ensure the above is ordered vs clearing the OWN bit */
        dma_wmb();

        /* Clean status (which resets own bit) */
        if (entry == (priv->rx_q_entries - 1))
                rxdes->rxdes0 = cpu_to_le32(priv->rxdes0_edorr_mask);
        else
                rxdes->rxdes0 = 0;

        return err;
}

static unsigned int ftgmac100_next_rx_pointer(struct ftgmac100 *priv,
                                              unsigned int pointer)
{
        return (pointer + 1) & (priv->rx_q_entries - 1);
}

static void ftgmac100_rx_packet_error(struct ftgmac100 *priv, u32 status)
{
        struct net_device *netdev = priv->netdev;

        if (status & FTGMAC100_RXDES0_RX_ERR)
                netdev->stats.rx_errors++;

        if (status & FTGMAC100_RXDES0_CRC_ERR)
                netdev->stats.rx_crc_errors++;

        if (status & (FTGMAC100_RXDES0_FTL |
                      FTGMAC100_RXDES0_RUNT |
                      FTGMAC100_RXDES0_RX_ODD_NB))
                netdev->stats.rx_length_errors++;
}

static bool ftgmac100_rx_packet(struct ftgmac100 *priv, int *processed)
{
        struct net_device *netdev = priv->netdev;
        struct ftgmac100_rxdes *rxdes;
        struct sk_buff *skb;
        unsigned int pointer, size;
        u32 status, csum_vlan;
        dma_addr_t map;

        /* Grab next RX descriptor */
        pointer = priv->rx_pointer;
        rxdes = &priv->rxdes[pointer];

        /* Grab descriptor status */
        status = le32_to_cpu(rxdes->rxdes0);

        /* Do we have a packet ? */
        if (!(status & FTGMAC100_RXDES0_RXPKT_RDY))
                return false;

        /* Order subsequent reads with the test for the ready bit */
        dma_rmb();

        /* We don't cope with fragmented RX packets */
        if (unlikely(!(status & FTGMAC100_RXDES0_FRS) ||
                     !(status & FTGMAC100_RXDES0_LRS)))
                goto drop;

        /* Grab received size and csum vlan field in the descriptor */
        size = status & FTGMAC100_RXDES0_VDBC;
        csum_vlan = le32_to_cpu(rxdes->rxdes1);

        /* Any error (other than csum offload) flagged ? */
        if (unlikely(status & RXDES0_ANY_ERROR)) {
                /* Correct for incorrect flagging of runt packets
                 * with vlan tags... Just accept a runt packet that
                 * has been flagged as vlan and whose size is at
                 * least 60 bytes.
                 */
                if ((status & FTGMAC100_RXDES0_RUNT) &&
                    (csum_vlan & FTGMAC100_RXDES1_VLANTAG_AVAIL) &&
                    (size >= 60))
                        status &= ~FTGMAC100_RXDES0_RUNT;

                /* Any error still in there ? */
                if (status & RXDES0_ANY_ERROR) {
                        ftgmac100_rx_packet_error(priv, status);
                        goto drop;
                }
        }

        /* If the packet had no skb (failed to allocate earlier)
         * then try to allocate one and skip
         */
        skb = priv->rx_skbs[pointer];
        if (!unlikely(skb)) {
                ftgmac100_alloc_rx_buf(priv, pointer, rxdes, GFP_ATOMIC);
                goto drop;
        }

        if (unlikely(status & FTGMAC100_RXDES0_MULTICAST))
                netdev->stats.multicast++;

        /* If the HW found checksum errors, bounce it to software.
         *
         * If we didn't, we need to see if the packet was recognized
         * by HW as one of the supported checksummed protocols before
         * we accept the HW test results.
         */
        if (netdev->features & NETIF_F_RXCSUM) {
                u32 err_bits = FTGMAC100_RXDES1_TCP_CHKSUM_ERR |
                        FTGMAC100_RXDES1_UDP_CHKSUM_ERR |
                        FTGMAC100_RXDES1_IP_CHKSUM_ERR;
                if ((csum_vlan & err_bits) ||
                    !(csum_vlan & FTGMAC100_RXDES1_PROT_MASK))
                        skb->ip_summed = CHECKSUM_NONE;
                else
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
        }

        /* Transfer received size to skb */
        skb_put(skb, size);

        /* Extract vlan tag */
        if ((netdev->features & NETIF_F_HW_VLAN_CTAG_RX) &&
            (csum_vlan & FTGMAC100_RXDES1_VLANTAG_AVAIL))
                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
                                       csum_vlan & 0xffff);

        /* Tear down DMA mapping, do necessary cache management */
        map = le32_to_cpu(rxdes->rxdes3);

#if defined(CONFIG_ARM) && !defined(CONFIG_ARM_DMA_USE_IOMMU)
        /* When we don't have an iommu, we can save cycles by not
         * invalidating the cache for the part of the packet that
         * wasn't received.
         */
        dma_unmap_single(priv->dev, map, size, DMA_FROM_DEVICE);
#else
        dma_unmap_single(priv->dev, map, RX_BUF_SIZE, DMA_FROM_DEVICE);
#endif


        /* Resplenish rx ring */
        ftgmac100_alloc_rx_buf(priv, pointer, rxdes, GFP_ATOMIC);
        priv->rx_pointer = ftgmac100_next_rx_pointer(priv, pointer);

        skb->protocol = eth_type_trans(skb, netdev);

        netdev->stats.rx_packets++;
        netdev->stats.rx_bytes += size;

        /* push packet to protocol stack */
        if (skb->ip_summed == CHECKSUM_NONE)
                netif_receive_skb(skb);
        else
                napi_gro_receive(&priv->napi, skb);

        (*processed)++;
        return true;

 drop:
        /* Clean rxdes0 (which resets own bit) */
        rxdes->rxdes0 = cpu_to_le32(status & priv->rxdes0_edorr_mask);
        priv->rx_pointer = ftgmac100_next_rx_pointer(priv, pointer);
        netdev->stats.rx_dropped++;
        return true;
}

static u32 ftgmac100_base_tx_ctlstat(struct ftgmac100 *priv,
                                     unsigned int index)
{
        if (index == (priv->tx_q_entries - 1))
                return priv->txdes0_edotr_mask;
        else
                return 0;
}

static unsigned int ftgmac100_next_tx_pointer(struct ftgmac100 *priv,
                                              unsigned int pointer)
{
        return (pointer + 1) & (priv->tx_q_entries - 1);
}

static u32 ftgmac100_tx_buf_avail(struct ftgmac100 *priv)
{
        /* Returns the number of available slots in the TX queue
         *
         * This always leaves one free slot so we don't have to
         * worry about empty vs. full, and this simplifies the
         * test for ftgmac100_tx_buf_cleanable() below
         */
        return (priv->tx_clean_pointer - priv->tx_pointer - 1) &
                (priv->tx_q_entries - 1);
}

static bool ftgmac100_tx_buf_cleanable(struct ftgmac100 *priv)
{
        return priv->tx_pointer != priv->tx_clean_pointer;
}

static void ftgmac100_free_tx_packet(struct ftgmac100 *priv,
                                     unsigned int pointer,
                                     struct sk_buff *skb,
                                     struct ftgmac100_txdes *txdes,
                                     u32 ctl_stat)
{
        dma_addr_t map = le32_to_cpu(txdes->txdes3);
        size_t len;

        if (ctl_stat & FTGMAC100_TXDES0_FTS) {
                len = skb_headlen(skb);
                dma_unmap_single(priv->dev, map, len, DMA_TO_DEVICE);
        } else {
                len = FTGMAC100_TXDES0_TXBUF_SIZE(ctl_stat);
                dma_unmap_page(priv->dev, map, len, DMA_TO_DEVICE);
        }

        /* Free SKB on last segment */
        if (ctl_stat & FTGMAC100_TXDES0_LTS)
                dev_kfree_skb(skb);
        priv->tx_skbs[pointer] = NULL;
}

static bool ftgmac100_tx_complete_packet(struct ftgmac100 *priv)
{
        struct net_device *netdev = priv->netdev;
        struct ftgmac100_txdes *txdes;
        struct sk_buff *skb;
        unsigned int pointer;
        u32 ctl_stat;

        pointer = priv->tx_clean_pointer;
        txdes = &priv->txdes[pointer];

        ctl_stat = le32_to_cpu(txdes->txdes0);
        if (ctl_stat & FTGMAC100_TXDES0_TXDMA_OWN)
                return false;

        skb = priv->tx_skbs[pointer];
        netdev->stats.tx_packets++;
        netdev->stats.tx_bytes += skb->len;
        ftgmac100_free_tx_packet(priv, pointer, skb, txdes, ctl_stat);
        txdes->txdes0 = cpu_to_le32(ctl_stat & priv->txdes0_edotr_mask);

        priv->tx_clean_pointer = ftgmac100_next_tx_pointer(priv, pointer);

        return true;
}

static void ftgmac100_tx_complete(struct ftgmac100 *priv)
{
        struct net_device *netdev = priv->netdev;

        /* Process all completed packets */
        while (ftgmac100_tx_buf_cleanable(priv) &&
               ftgmac100_tx_complete_packet(priv))
                ;

        /* Restart queue if needed */
        smp_mb();
        if (unlikely(netif_queue_stopped(netdev) &&
                     ftgmac100_tx_buf_avail(priv) >= TX_THRESHOLD)) {
                struct netdev_queue *txq;

                txq = netdev_get_tx_queue(netdev, 0);
                __netif_tx_lock(txq, smp_processor_id());
                if (netif_queue_stopped(netdev) &&
                    ftgmac100_tx_buf_avail(priv) >= TX_THRESHOLD)
                        netif_wake_queue(netdev);
                __netif_tx_unlock(txq);
        }
}

static bool ftgmac100_prep_tx_csum(struct sk_buff *skb, u32 *csum_vlan)
{
        if (skb->protocol == cpu_to_be16(ETH_P_IP)) {
                u8 ip_proto = ip_hdr(skb)->protocol;

                *csum_vlan |= FTGMAC100_TXDES1_IP_CHKSUM;
                switch(ip_proto) {
                case IPPROTO_TCP:
                        *csum_vlan |= FTGMAC100_TXDES1_TCP_CHKSUM;
                        return true;
                case IPPROTO_UDP:
                        *csum_vlan |= FTGMAC100_TXDES1_UDP_CHKSUM;
                        return true;
                case IPPROTO_IP:
                        return true;
                }
        }
        return skb_checksum_help(skb) == 0;
}

static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
                                             struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        struct ftgmac100_txdes *txdes, *first;
        unsigned int pointer, nfrags, len, i, j;
        u32 f_ctl_stat, ctl_stat, csum_vlan;
        dma_addr_t map;

        /* The HW doesn't pad small frames */
        if (eth_skb_pad(skb)) {
                netdev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        /* Reject oversize packets */
        if (unlikely(skb->len > MAX_PKT_SIZE)) {
                if (net_ratelimit())
                        netdev_dbg(netdev, "tx packet too big\n");
                goto drop;
        }

        /* Do we have a limit on #fragments ? I yet have to get a reply
         * from Aspeed. If there's one I haven't hit it.
         */
        nfrags = skb_shinfo(skb)->nr_frags;

        /* Setup HW checksumming */
        csum_vlan = 0;
        if (skb->ip_summed == CHECKSUM_PARTIAL &&
            !ftgmac100_prep_tx_csum(skb, &csum_vlan))
                goto drop;

        /* Add VLAN tag */
        if (skb_vlan_tag_present(skb)) {
                csum_vlan |= FTGMAC100_TXDES1_INS_VLANTAG;
                csum_vlan |= skb_vlan_tag_get(skb) & 0xffff;
        }

        /* Get header len */
        len = skb_headlen(skb);

        /* Map the packet head */
        map = dma_map_single(priv->dev, skb->data, len, DMA_TO_DEVICE);
        if (dma_mapping_error(priv->dev, map)) {
                if (net_ratelimit())
                        netdev_err(netdev, "map tx packet head failed\n");
                goto drop;
        }

        /* Grab the next free tx descriptor */
        pointer = priv->tx_pointer;
        txdes = first = &priv->txdes[pointer];

        /* Setup it up with the packet head. Don't write the head to the
         * ring just yet
         */
        priv->tx_skbs[pointer] = skb;
        f_ctl_stat = ftgmac100_base_tx_ctlstat(priv, pointer);
        f_ctl_stat |= FTGMAC100_TXDES0_TXDMA_OWN;
        f_ctl_stat |= FTGMAC100_TXDES0_TXBUF_SIZE(len);
        f_ctl_stat |= FTGMAC100_TXDES0_FTS;
        if (nfrags == 0)
                f_ctl_stat |= FTGMAC100_TXDES0_LTS;
        txdes->txdes3 = cpu_to_le32(map);
        txdes->txdes1 = cpu_to_le32(csum_vlan);

        /* Next descriptor */
        pointer = ftgmac100_next_tx_pointer(priv, pointer);

        /* Add the fragments */
        for (i = 0; i < nfrags; i++) {
                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

                len = skb_frag_size(frag);

                /* Map it */
                map = skb_frag_dma_map(priv->dev, frag, 0, len,
                                       DMA_TO_DEVICE);
                if (dma_mapping_error(priv->dev, map))
                        goto dma_err;

                /* Setup descriptor */
                priv->tx_skbs[pointer] = skb;
                txdes = &priv->txdes[pointer];
                ctl_stat = ftgmac100_base_tx_ctlstat(priv, pointer);
                ctl_stat |= FTGMAC100_TXDES0_TXDMA_OWN;
                ctl_stat |= FTGMAC100_TXDES0_TXBUF_SIZE(len);
                if (i == (nfrags - 1))
                        ctl_stat |= FTGMAC100_TXDES0_LTS;
                txdes->txdes0 = cpu_to_le32(ctl_stat);
                txdes->txdes1 = 0;
                txdes->txdes3 = cpu_to_le32(map);

                /* Next one */
                pointer = ftgmac100_next_tx_pointer(priv, pointer);
        }

        /* Order the previous packet and descriptor udpates
         * before setting the OWN bit on the first descriptor.
         */
        dma_wmb();
        first->txdes0 = cpu_to_le32(f_ctl_stat);

        /* Update next TX pointer */
        priv->tx_pointer = pointer;

        /* If there isn't enough room for all the fragments of a new packet
         * in the TX ring, stop the queue. The sequence below is race free
         * vs. a concurrent restart in ftgmac100_poll()
         */
        if (unlikely(ftgmac100_tx_buf_avail(priv) < TX_THRESHOLD)) {
                netif_stop_queue(netdev);
                /* Order the queue stop with the test below */
                smp_mb();
                if (ftgmac100_tx_buf_avail(priv) >= TX_THRESHOLD)
                        netif_wake_queue(netdev);
        }

        /* Poke transmitter to read the updated TX descriptors */
        iowrite32(1, priv->base + FTGMAC100_OFFSET_NPTXPD);

        return NETDEV_TX_OK;

 dma_err:
        if (net_ratelimit())
                netdev_err(netdev, "map tx fragment failed\n");

        /* Free head */
        pointer = priv->tx_pointer;
        ftgmac100_free_tx_packet(priv, pointer, skb, first, f_ctl_stat);
        first->txdes0 = cpu_to_le32(f_ctl_stat & priv->txdes0_edotr_mask);

        /* Then all fragments */
        for (j = 0; j < i; j++) {
                pointer = ftgmac100_next_tx_pointer(priv, pointer);
                txdes = &priv->txdes[pointer];
                ctl_stat = le32_to_cpu(txdes->txdes0);
                ftgmac100_free_tx_packet(priv, pointer, skb, txdes, ctl_stat);
                txdes->txdes0 = cpu_to_le32(ctl_stat & priv->txdes0_edotr_mask);
        }

        /* This cannot be reached if we successfully mapped the
         * last fragment, so we know ftgmac100_free_tx_packet()
         * hasn't freed the skb yet.
         */
 drop:
        /* Drop the packet */
        dev_kfree_skb_any(skb);
        netdev->stats.tx_dropped++;

        return NETDEV_TX_OK;
}

static void ftgmac100_free_buffers(struct ftgmac100 *priv)
{
        int i;

        /* Free all RX buffers */
        for (i = 0; i < priv->rx_q_entries; i++) {
                struct ftgmac100_rxdes *rxdes = &priv->rxdes[i];
                struct sk_buff *skb = priv->rx_skbs[i];
                dma_addr_t map = le32_to_cpu(rxdes->rxdes3);

                if (!skb)
                        continue;

                priv->rx_skbs[i] = NULL;
                dma_unmap_single(priv->dev, map, RX_BUF_SIZE, DMA_FROM_DEVICE);
                dev_kfree_skb_any(skb);
        }

        /* Free all TX buffers */
        for (i = 0; i < priv->tx_q_entries; i++) {
                struct ftgmac100_txdes *txdes = &priv->txdes[i];
                struct sk_buff *skb = priv->tx_skbs[i];

                if (!skb)
                        continue;
                ftgmac100_free_tx_packet(priv, i, skb, txdes,
                                         le32_to_cpu(txdes->txdes0));
        }
}

static void ftgmac100_free_rings(struct ftgmac100 *priv)
{
        /* Free skb arrays */
        kfree(priv->rx_skbs);
        kfree(priv->tx_skbs);

        /* Free descriptors */
        if (priv->rxdes)
                dma_free_coherent(priv->dev, MAX_RX_QUEUE_ENTRIES *
                                  sizeof(struct ftgmac100_rxdes),
                                  priv->rxdes, priv->rxdes_dma);
        priv->rxdes = NULL;

        if (priv->txdes)
                dma_free_coherent(priv->dev, MAX_TX_QUEUE_ENTRIES *
                                  sizeof(struct ftgmac100_txdes),
                                  priv->txdes, priv->txdes_dma);
        priv->txdes = NULL;

        /* Free scratch packet buffer */
        if (priv->rx_scratch)
                dma_free_coherent(priv->dev, RX_BUF_SIZE,
                                  priv->rx_scratch, priv->rx_scratch_dma);
}

static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
{
        /* Allocate skb arrays */
        priv->rx_skbs = kcalloc(MAX_RX_QUEUE_ENTRIES, sizeof(void *),
                                GFP_KERNEL);
        if (!priv->rx_skbs)
                return -ENOMEM;
        priv->tx_skbs = kcalloc(MAX_TX_QUEUE_ENTRIES, sizeof(void *),
                                GFP_KERNEL);
        if (!priv->tx_skbs)
                return -ENOMEM;

        /* Allocate descriptors */
        priv->rxdes = dma_alloc_coherent(priv->dev,
                                         MAX_RX_QUEUE_ENTRIES * sizeof(struct ftgmac100_rxdes),
                                         &priv->rxdes_dma, GFP_KERNEL);
        if (!priv->rxdes)
                return -ENOMEM;
        priv->txdes = dma_alloc_coherent(priv->dev,
                                         MAX_TX_QUEUE_ENTRIES * sizeof(struct ftgmac100_txdes),
                                         &priv->txdes_dma, GFP_KERNEL);
        if (!priv->txdes)
                return -ENOMEM;

        /* Allocate scratch packet buffer */
        priv->rx_scratch = dma_alloc_coherent(priv->dev,
                                              RX_BUF_SIZE,
                                              &priv->rx_scratch_dma,
                                              GFP_KERNEL);
        if (!priv->rx_scratch)
                return -ENOMEM;

        return 0;
}

static void ftgmac100_init_rings(struct ftgmac100 *priv)
{
        struct ftgmac100_rxdes *rxdes = NULL;
        struct ftgmac100_txdes *txdes = NULL;
        int i;

        /* Update entries counts */
        priv->rx_q_entries = priv->new_rx_q_entries;
        priv->tx_q_entries = priv->new_tx_q_entries;

        if (WARN_ON(priv->rx_q_entries < MIN_RX_QUEUE_ENTRIES))
                return;

        /* Initialize RX ring */
        for (i = 0; i < priv->rx_q_entries; i++) {
                rxdes = &priv->rxdes[i];
                rxdes->rxdes0 = 0;
                rxdes->rxdes3 = cpu_to_le32(priv->rx_scratch_dma);
        }
        /* Mark the end of the ring */
        rxdes->rxdes0 |= cpu_to_le32(priv->rxdes0_edorr_mask);

        if (WARN_ON(priv->tx_q_entries < MIN_RX_QUEUE_ENTRIES))
                return;

        /* Initialize TX ring */
        for (i = 0; i < priv->tx_q_entries; i++) {
                txdes = &priv->txdes[i];
                txdes->txdes0 = 0;
        }
        txdes->txdes0 |= cpu_to_le32(priv->txdes0_edotr_mask);
}

static int ftgmac100_alloc_rx_buffers(struct ftgmac100 *priv)
{
        int i;

        for (i = 0; i < priv->rx_q_entries; i++) {
                struct ftgmac100_rxdes *rxdes = &priv->rxdes[i];

                if (ftgmac100_alloc_rx_buf(priv, i, rxdes, GFP_KERNEL))
                        return -ENOMEM;
        }
        return 0;
}

static void ftgmac100_adjust_link(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        struct phy_device *phydev = netdev->phydev;
        bool tx_pause, rx_pause;
        int new_speed;

        /* We store "no link" as speed 0 */
        if (!phydev->link)
                new_speed = 0;
        else
                new_speed = phydev->speed;

        /* Grab pause settings from PHY if configured to do so */
        if (priv->aneg_pause) {
                rx_pause = tx_pause = phydev->pause;
                if (phydev->asym_pause)
                        tx_pause = !rx_pause;
        } else {
                rx_pause = priv->rx_pause;
                tx_pause = priv->tx_pause;
        }

        /* Link hasn't changed, do nothing */
        if (phydev->speed == priv->cur_speed &&
            phydev->duplex == priv->cur_duplex &&
            rx_pause == priv->rx_pause &&
            tx_pause == priv->tx_pause)
                return;

        /* Print status if we have a link or we had one and just lost it,
         * don't print otherwise.
         */
        if (new_speed || priv->cur_speed)
                phy_print_status(phydev);

        priv->cur_speed = new_speed;
        priv->cur_duplex = phydev->duplex;
        priv->rx_pause = rx_pause;
        priv->tx_pause = tx_pause;

        /* Link is down, do nothing else */
        if (!new_speed)
                return;

        /* Disable all interrupts */
        iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);

        /* Reset the adapter asynchronously */
        schedule_work(&priv->reset_task);
}

static int ftgmac100_mii_probe(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        struct platform_device *pdev = to_platform_device(priv->dev);
        struct device_node *np = pdev->dev.of_node;
        struct phy_device *phydev;
        phy_interface_t phy_intf;
        int err;

        /* Default to RGMII. It's a gigabit part after all */
        err = of_get_phy_mode(np, &phy_intf);
        if (err)
                phy_intf = PHY_INTERFACE_MODE_RGMII;

        /* Aspeed only supports these. I don't know about other IP
         * block vendors so I'm going to just let them through for
         * now. Note that this is only a warning if for some obscure
         * reason the DT really means to lie about it or it's a newer
         * part we don't know about.
         *
         * On the Aspeed SoC there are additionally straps and SCU
         * control bits that could tell us what the interface is
         * (or allow us to configure it while the IP block is held
         * in reset). For now I chose to keep this driver away from
         * those SoC specific bits and assume the device-tree is
         * right and the SCU has been configured properly by pinmux
         * or the firmware.
         */
        if (priv->is_aspeed && !(phy_interface_mode_is_rgmii(phy_intf))) {
                netdev_warn(netdev,
                            "Unsupported PHY mode %s !\n",
                            phy_modes(phy_intf));
        }

        phydev = phy_find_first(priv->mii_bus);
        if (!phydev) {
                netdev_info(netdev, "%s: no PHY found\n", netdev->name);
                return -ENODEV;
        }

        phydev = phy_connect(netdev, phydev_name(phydev),
                             &ftgmac100_adjust_link, phy_intf);

        if (IS_ERR(phydev)) {
                netdev_err(netdev, "%s: Could not attach to PHY\n", netdev->name);
                return PTR_ERR(phydev);
        }

        /* Indicate that we support PAUSE frames (see comment in
         * Documentation/networking/phy.rst)
         */
        phy_support_asym_pause(phydev);

        /* Display what we found */
        phy_attached_info(phydev);

        return 0;
}

static int ftgmac100_mdiobus_read(struct mii_bus *bus, int phy_addr, int regnum)
{
        struct net_device *netdev = bus->priv;
        struct ftgmac100 *priv = netdev_priv(netdev);
        unsigned int phycr;
        int i;

        phycr = ioread32(priv->base + FTGMAC100_OFFSET_PHYCR);

        /* preserve MDC cycle threshold */
        phycr &= FTGMAC100_PHYCR_MDC_CYCTHR_MASK;

        phycr |= FTGMAC100_PHYCR_PHYAD(phy_addr) |
                 FTGMAC100_PHYCR_REGAD(regnum) |
                 FTGMAC100_PHYCR_MIIRD;

        iowrite32(phycr, priv->base + FTGMAC100_OFFSET_PHYCR);

        for (i = 0; i < 10; i++) {
                phycr = ioread32(priv->base + FTGMAC100_OFFSET_PHYCR);

                if ((phycr & FTGMAC100_PHYCR_MIIRD) == 0) {
                        int data;

                        data = ioread32(priv->base + FTGMAC100_OFFSET_PHYDATA);
                        return FTGMAC100_PHYDATA_MIIRDATA(data);
                }

                udelay(100);
        }

        netdev_err(netdev, "mdio read timed out\n");
        return -EIO;
}

static int ftgmac100_mdiobus_write(struct mii_bus *bus, int phy_addr,
                                   int regnum, u16 value)
{
        struct net_device *netdev = bus->priv;
        struct ftgmac100 *priv = netdev_priv(netdev);
        unsigned int phycr;
        int data;
        int i;

        phycr = ioread32(priv->base + FTGMAC100_OFFSET_PHYCR);

        /* preserve MDC cycle threshold */
        phycr &= FTGMAC100_PHYCR_MDC_CYCTHR_MASK;

        phycr |= FTGMAC100_PHYCR_PHYAD(phy_addr) |
                 FTGMAC100_PHYCR_REGAD(regnum) |
                 FTGMAC100_PHYCR_MIIWR;

        data = FTGMAC100_PHYDATA_MIIWDATA(value);

        iowrite32(data, priv->base + FTGMAC100_OFFSET_PHYDATA);
        iowrite32(phycr, priv->base + FTGMAC100_OFFSET_PHYCR);

        for (i = 0; i < 10; i++) {
                phycr = ioread32(priv->base + FTGMAC100_OFFSET_PHYCR);

                if ((phycr & FTGMAC100_PHYCR_MIIWR) == 0)
                        return 0;

                udelay(100);
        }

        netdev_err(netdev, "mdio write timed out\n");
        return -EIO;
}

static void ftgmac100_get_drvinfo(struct net_device *netdev,
                                  struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
        strlcpy(info->bus_info, dev_name(&netdev->dev), sizeof(info->bus_info));
}

static void ftgmac100_get_ringparam(struct net_device *netdev,
                                    struct ethtool_ringparam *ering)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        memset(ering, 0, sizeof(*ering));
        ering->rx_max_pending = MAX_RX_QUEUE_ENTRIES;
        ering->tx_max_pending = MAX_TX_QUEUE_ENTRIES;
        ering->rx_pending = priv->rx_q_entries;
        ering->tx_pending = priv->tx_q_entries;
}

static int ftgmac100_set_ringparam(struct net_device *netdev,
                                   struct ethtool_ringparam *ering)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        if (ering->rx_pending > MAX_RX_QUEUE_ENTRIES ||
            ering->tx_pending > MAX_TX_QUEUE_ENTRIES ||
            ering->rx_pending < MIN_RX_QUEUE_ENTRIES ||
            ering->tx_pending < MIN_TX_QUEUE_ENTRIES ||
            !is_power_of_2(ering->rx_pending) ||
            !is_power_of_2(ering->tx_pending))
                return -EINVAL;

        priv->new_rx_q_entries = ering->rx_pending;
        priv->new_tx_q_entries = ering->tx_pending;
        if (netif_running(netdev))
                schedule_work(&priv->reset_task);

        return 0;
}

static void ftgmac100_get_pauseparam(struct net_device *netdev,
                                     struct ethtool_pauseparam *pause)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        pause->autoneg = priv->aneg_pause;
        pause->tx_pause = priv->tx_pause;
        pause->rx_pause = priv->rx_pause;
}

static int ftgmac100_set_pauseparam(struct net_device *netdev,
                                    struct ethtool_pauseparam *pause)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        struct phy_device *phydev = netdev->phydev;

        priv->aneg_pause = pause->autoneg;
        priv->tx_pause = pause->tx_pause;
        priv->rx_pause = pause->rx_pause;

        if (phydev)
                phy_set_asym_pause(phydev, pause->rx_pause, pause->tx_pause);

        if (netif_running(netdev)) {
                if (!(phydev && priv->aneg_pause))
                        ftgmac100_config_pause(priv);
        }

        return 0;
}

static const struct ethtool_ops ftgmac100_ethtool_ops = {
        .get_drvinfo            = ftgmac100_get_drvinfo,
        .get_link               = ethtool_op_get_link,
        .get_link_ksettings     = phy_ethtool_get_link_ksettings,
        .set_link_ksettings     = phy_ethtool_set_link_ksettings,
        .nway_reset             = phy_ethtool_nway_reset,
        .get_ringparam          = ftgmac100_get_ringparam,
        .set_ringparam          = ftgmac100_set_ringparam,
        .get_pauseparam         = ftgmac100_get_pauseparam,
        .set_pauseparam         = ftgmac100_set_pauseparam,
};

static irqreturn_t ftgmac100_interrupt(int irq, void *dev_id)
{
        struct net_device *netdev = dev_id;
        struct ftgmac100 *priv = netdev_priv(netdev);
        unsigned int status, new_mask = FTGMAC100_INT_BAD;

        /* Fetch and clear interrupt bits, process abnormal ones */
        status = ioread32(priv->base + FTGMAC100_OFFSET_ISR);
        iowrite32(status, priv->base + FTGMAC100_OFFSET_ISR);
        if (unlikely(status & FTGMAC100_INT_BAD)) {

                /* RX buffer unavailable */
                if (status & FTGMAC100_INT_NO_RXBUF)
                        netdev->stats.rx_over_errors++;

                /* received packet lost due to RX FIFO full */
                if (status & FTGMAC100_INT_RPKT_LOST)
                        netdev->stats.rx_fifo_errors++;

                /* sent packet lost due to excessive TX collision */
                if (status & FTGMAC100_INT_XPKT_LOST)
                        netdev->stats.tx_fifo_errors++;

                /* AHB error -> Reset the chip */
                if (status & FTGMAC100_INT_AHB_ERR) {
                        if (net_ratelimit())
                                netdev_warn(netdev,
                                           "AHB bus error ! Resetting chip.\n");
                        iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);
                        schedule_work(&priv->reset_task);
                        return IRQ_HANDLED;
                }

                /* We may need to restart the MAC after such errors, delay
                 * this until after we have freed some Rx buffers though
                 */
                priv->need_mac_restart = true;

                /* Disable those errors until we restart */
                new_mask &= ~status;
        }

        /* Only enable "bad" interrupts while NAPI is on */
        iowrite32(new_mask, priv->base + FTGMAC100_OFFSET_IER);

        /* Schedule NAPI bh */
        napi_schedule_irqoff(&priv->napi);

        return IRQ_HANDLED;
}

static bool ftgmac100_check_rx(struct ftgmac100 *priv)
{
        struct ftgmac100_rxdes *rxdes = &priv->rxdes[priv->rx_pointer];

        /* Do we have a packet ? */
        return !!(rxdes->rxdes0 & cpu_to_le32(FTGMAC100_RXDES0_RXPKT_RDY));
}

static int ftgmac100_poll(struct napi_struct *napi, int budget)
{
        struct ftgmac100 *priv = container_of(napi, struct ftgmac100, napi);
        int work_done = 0;
        bool more;

        /* Handle TX completions */
        if (ftgmac100_tx_buf_cleanable(priv))
                ftgmac100_tx_complete(priv);

        /* Handle RX packets */
        do {
                more = ftgmac100_rx_packet(priv, &work_done);
        } while (more && work_done < budget);


        /* The interrupt is telling us to kick the MAC back to life
         * after an RX overflow
         */
        if (unlikely(priv->need_mac_restart)) {
                ftgmac100_start_hw(priv);
                priv->need_mac_restart = false;

                /* Re-enable "bad" interrupts */
                iowrite32(FTGMAC100_INT_BAD,
                          priv->base + FTGMAC100_OFFSET_IER);
        }

        /* As long as we are waiting for transmit packets to be
         * completed we keep NAPI going
         */
        if (ftgmac100_tx_buf_cleanable(priv))
                work_done = budget;

        if (work_done < budget) {
                /* We are about to re-enable all interrupts. However
                 * the HW has been latching RX/TX packet interrupts while
                 * they were masked. So we clear them first, then we need
                 * to re-check if there's something to process
                 */
                iowrite32(FTGMAC100_INT_RXTX,
                          priv->base + FTGMAC100_OFFSET_ISR);

                /* Push the above (and provides a barrier vs. subsequent
                 * reads of the descriptor).
                 */
                ioread32(priv->base + FTGMAC100_OFFSET_ISR);

                /* Check RX and TX descriptors for more work to do */
                if (ftgmac100_check_rx(priv) ||
                    ftgmac100_tx_buf_cleanable(priv))
                        return budget;

                /* deschedule NAPI */
                napi_complete(napi);

                /* enable all interrupts */
                iowrite32(FTGMAC100_INT_ALL,
                          priv->base + FTGMAC100_OFFSET_IER);
        }

        return work_done;
}

static int ftgmac100_init_all(struct ftgmac100 *priv, bool ignore_alloc_err)
{
        int err = 0;

        /* Re-init descriptors (adjust queue sizes) */
        ftgmac100_init_rings(priv);

        /* Realloc rx descriptors */
        err = ftgmac100_alloc_rx_buffers(priv);
        if (err && !ignore_alloc_err)
                return err;

        /* Reinit and restart HW */
        ftgmac100_init_hw(priv);
        ftgmac100_config_pause(priv);
        ftgmac100_start_hw(priv);

        /* Re-enable the device */
        napi_enable(&priv->napi);
        netif_start_queue(priv->netdev);

        /* Enable all interrupts */
        iowrite32(FTGMAC100_INT_ALL, priv->base + FTGMAC100_OFFSET_IER);

        return err;
}

static void ftgmac100_reset_task(struct work_struct *work)
{
        struct ftgmac100 *priv = container_of(work, struct ftgmac100,
                                              reset_task);
        struct net_device *netdev = priv->netdev;
        int err;

        netdev_dbg(netdev, "Resetting NIC...\n");

        /* Lock the world */
        rtnl_lock();
        if (netdev->phydev)
                mutex_lock(&netdev->phydev->lock);
        if (priv->mii_bus)
                mutex_lock(&priv->mii_bus->mdio_lock);


        /* Check if the interface is still up */
        if (!netif_running(netdev))
                goto bail;

        /* Stop the network stack */
        netif_trans_update(netdev);
        napi_disable(&priv->napi);
        netif_tx_disable(netdev);

        /* Stop and reset the MAC */
        ftgmac100_stop_hw(priv);
        err = ftgmac100_reset_and_config_mac(priv);
        if (err) {
                /* Not much we can do ... it might come back... */
                netdev_err(netdev, "attempting to continue...\n");
        }

        /* Free all rx and tx buffers */
        ftgmac100_free_buffers(priv);

        /* Setup everything again and restart chip */
        ftgmac100_init_all(priv, true);

        netdev_dbg(netdev, "Reset done !\n");
 bail:
        if (priv->mii_bus)
                mutex_unlock(&priv->mii_bus->mdio_lock);
        if (netdev->phydev)
                mutex_unlock(&netdev->phydev->lock);
        rtnl_unlock();
}

static int ftgmac100_open(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        int err;

        /* Allocate ring buffers  */
        err = ftgmac100_alloc_rings(priv);
        if (err) {
                netdev_err(netdev, "Failed to allocate descriptors\n");
                return err;
        }

        /* When using NC-SI we force the speed to 100Mbit/s full duplex,
         *
         * Otherwise we leave it set to 0 (no link), the link
         * message from the PHY layer will handle setting it up to
         * something else if needed.
         */
        if (priv->use_ncsi) {
                priv->cur_duplex = DUPLEX_FULL;
                priv->cur_speed = SPEED_100;
        } else {
                priv->cur_duplex = 0;
                priv->cur_speed = 0;
        }

        /* Reset the hardware */
        err = ftgmac100_reset_and_config_mac(priv);
        if (err)
                goto err_hw;

        /* Initialize NAPI */
        netif_napi_add(netdev, &priv->napi, ftgmac100_poll, 64);

        /* Grab our interrupt */
        err = request_irq(netdev->irq, ftgmac100_interrupt, 0, netdev->name, netdev);
        if (err) {
                netdev_err(netdev, "failed to request irq %d\n", netdev->irq);
                goto err_irq;
        }

        /* Start things up */
        err = ftgmac100_init_all(priv, false);
        if (err) {
                netdev_err(netdev, "Failed to allocate packet buffers\n");
                goto err_alloc;
        }

        if (netdev->phydev) {
                /* If we have a PHY, start polling */
                phy_start(netdev->phydev);
        } else if (priv->use_ncsi) {
                /* If using NC-SI, set our carrier on and start the stack */
                netif_carrier_on(netdev);

                /* Start the NCSI device */
                err = ncsi_start_dev(priv->ndev);
                if (err)
                        goto err_ncsi;
        }

        return 0;

 err_ncsi:
        napi_disable(&priv->napi);
        netif_stop_queue(netdev);
 err_alloc:
        ftgmac100_free_buffers(priv);
        free_irq(netdev->irq, netdev);
 err_irq:
        netif_napi_del(&priv->napi);
 err_hw:
        iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);
        ftgmac100_free_rings(priv);
        return err;
}

static int ftgmac100_stop(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        /* Note about the reset task: We are called with the rtnl lock
         * held, so we are synchronized against the core of the reset
         * task. We must not try to synchronously cancel it otherwise
         * we can deadlock. But since it will test for netif_running()
         * which has already been cleared by the net core, we don't
         * anything special to do.
         */

        /* disable all interrupts */
        iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);

        netif_stop_queue(netdev);
        napi_disable(&priv->napi);
        netif_napi_del(&priv->napi);
        if (netdev->phydev)
                phy_stop(netdev->phydev);
        else if (priv->use_ncsi)
                ncsi_stop_dev(priv->ndev);

        ftgmac100_stop_hw(priv);
        free_irq(netdev->irq, netdev);
        ftgmac100_free_buffers(priv);
        ftgmac100_free_rings(priv);

        return 0;
}

static void ftgmac100_tx_timeout(struct net_device *netdev, unsigned int txqueue)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        /* Disable all interrupts */
        iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);

        /* Do the reset outside of interrupt context */
        schedule_work(&priv->reset_task);
}

static int ftgmac100_set_features(struct net_device *netdev,
                                  netdev_features_t features)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        netdev_features_t changed = netdev->features ^ features;

        if (!netif_running(netdev))
                return 0;

        /* Update the vlan filtering bit */
        if (changed & NETIF_F_HW_VLAN_CTAG_RX) {
                u32 maccr;

                maccr = ioread32(priv->base + FTGMAC100_OFFSET_MACCR);
                if (priv->netdev->features & NETIF_F_HW_VLAN_CTAG_RX)
                        maccr |= FTGMAC100_MACCR_RM_VLAN;
                else
                        maccr &= ~FTGMAC100_MACCR_RM_VLAN;
                iowrite32(maccr, priv->base + FTGMAC100_OFFSET_MACCR);
        }

        return 0;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static void ftgmac100_poll_controller(struct net_device *netdev)
{
        unsigned long flags;

        local_irq_save(flags);
        ftgmac100_interrupt(netdev->irq, netdev);
        local_irq_restore(flags);
}
#endif

static const struct net_device_ops ftgmac100_netdev_ops = {
        .ndo_open               = ftgmac100_open,
        .ndo_stop               = ftgmac100_stop,
        .ndo_start_xmit         = ftgmac100_hard_start_xmit,
        .ndo_set_mac_address    = ftgmac100_set_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_do_ioctl           = phy_do_ioctl,
        .ndo_tx_timeout         = ftgmac100_tx_timeout,
        .ndo_set_rx_mode        = ftgmac100_set_rx_mode,
        .ndo_set_features       = ftgmac100_set_features,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_poll_controller    = ftgmac100_poll_controller,
#endif
        .ndo_vlan_rx_add_vid    = ncsi_vlan_rx_add_vid,
        .ndo_vlan_rx_kill_vid   = ncsi_vlan_rx_kill_vid,
};

static int ftgmac100_setup_mdio(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);
        struct platform_device *pdev = to_platform_device(priv->dev);
        struct device_node *np = pdev->dev.of_node;
        struct device_node *mdio_np;
        int i, err = 0;
        u32 reg;

        /* initialize mdio bus */
        priv->mii_bus = mdiobus_alloc();
        if (!priv->mii_bus)
                return -EIO;

        if (of_device_is_compatible(np, "aspeed,ast2400-mac") ||
            of_device_is_compatible(np, "aspeed,ast2500-mac")) {
                /* The AST2600 has a separate MDIO controller */

                /* For the AST2400 and AST2500 this driver only supports the
                 * old MDIO interface
                 */
                reg = ioread32(priv->base + FTGMAC100_OFFSET_REVR);
                reg &= ~FTGMAC100_REVR_NEW_MDIO_INTERFACE;
                iowrite32(reg, priv->base + FTGMAC100_OFFSET_REVR);
        }

        priv->mii_bus->name = "ftgmac100_mdio";
        snprintf(priv->mii_bus->id, MII_BUS_ID_SIZE, "%s-%d",
                 pdev->name, pdev->id);
        priv->mii_bus->parent = priv->dev;
        priv->mii_bus->priv = priv->netdev;
        priv->mii_bus->read = ftgmac100_mdiobus_read;
        priv->mii_bus->write = ftgmac100_mdiobus_write;

        for (i = 0; i < PHY_MAX_ADDR; i++)
                priv->mii_bus->irq[i] = PHY_POLL;

        mdio_np = of_get_child_by_name(np, "mdio");

        err = of_mdiobus_register(priv->mii_bus, mdio_np);
        if (err) {
                dev_err(priv->dev, "Cannot register MDIO bus!\n");
                goto err_register_mdiobus;
        }

        of_node_put(mdio_np);

        return 0;

err_register_mdiobus:
        mdiobus_free(priv->mii_bus);
        return err;
}

static void ftgmac100_phy_disconnect(struct net_device *netdev)
{
        if (!netdev->phydev)
                return;

        phy_disconnect(netdev->phydev);
}

static void ftgmac100_destroy_mdio(struct net_device *netdev)
{
        struct ftgmac100 *priv = netdev_priv(netdev);

        if (!priv->mii_bus)
                return;

        mdiobus_unregister(priv->mii_bus);
        mdiobus_free(priv->mii_bus);
}

static void ftgmac100_ncsi_handler(struct ncsi_dev *nd)
{
        if (unlikely(nd->state != ncsi_dev_state_functional))
                return;

        netdev_dbg(nd->dev, "NCSI interface %s\n",
                   nd->link_up ? "up" : "down");
}

static int ftgmac100_setup_clk(struct ftgmac100 *priv)
{
        struct clk *clk;
        int rc;

        clk = devm_clk_get(priv->dev, NULL /* MACCLK */);
        if (IS_ERR(clk))
                return PTR_ERR(clk);
        priv->clk = clk;
        rc = clk_prepare_enable(priv->clk);
        if (rc)
                return rc;

        /* Aspeed specifies a 100MHz clock is required for up to
         * 1000Mbit link speeds. As NCSI is limited to 100Mbit, 25MHz
         * is sufficient
         */
        rc = clk_set_rate(priv->clk, priv->use_ncsi ? FTGMAC_25MHZ :
                          FTGMAC_100MHZ);
        if (rc)
                goto cleanup_clk;

        /* RCLK is for RMII, typically used for NCSI. Optional because it's not
         * necessary if it's the AST2400 MAC, or the MAC is configured for
         * RGMII, or the controller is not an ASPEED-based controller.
         */
        priv->rclk = devm_clk_get_optional(priv->dev, "RCLK");
        rc = clk_prepare_enable(priv->rclk);
        if (!rc)
                return 0;

cleanup_clk:
        clk_disable_unprepare(priv->clk);

        return rc;
}

static int ftgmac100_probe(struct platform_device *pdev)
{
        struct resource *res;
        int irq;
        struct net_device *netdev;
        struct ftgmac100 *priv;
        struct device_node *np;
        int err = 0;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENXIO;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        /* setup net_device */
        netdev = alloc_etherdev(sizeof(*priv));
        if (!netdev) {
                err = -ENOMEM;
                goto err_alloc_etherdev;
        }

        SET_NETDEV_DEV(netdev, &pdev->dev);

        netdev->ethtool_ops = &ftgmac100_ethtool_ops;
        netdev->netdev_ops = &ftgmac100_netdev_ops;
        netdev->watchdog_timeo = 5 * HZ;

        platform_set_drvdata(pdev, netdev);

        /* setup private data */
        priv = netdev_priv(netdev);
        priv->netdev = netdev;
        priv->dev = &pdev->dev;
        INIT_WORK(&priv->reset_task, ftgmac100_reset_task);

        /* map io memory */
        priv->res = request_mem_region(res->start, resource_size(res),
                                       dev_name(&pdev->dev));
        if (!priv->res) {
                dev_err(&pdev->dev, "Could not reserve memory region\n");
                err = -ENOMEM;
                goto err_req_mem;
        }

        priv->base = ioremap(res->start, resource_size(res));
        if (!priv->base) {
                dev_err(&pdev->dev, "Failed to ioremap ethernet registers\n");
                err = -EIO;
                goto err_ioremap;
        }

        netdev->irq = irq;

        /* Enable pause */
        priv->tx_pause = true;
        priv->rx_pause = true;
        priv->aneg_pause = true;

        /* MAC address from chip or random one */
        ftgmac100_initial_mac(priv);

        np = pdev->dev.of_node;
        if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac") ||
                   of_device_is_compatible(np, "aspeed,ast2500-mac") ||
                   of_device_is_compatible(np, "aspeed,ast2600-mac"))) {
                priv->rxdes0_edorr_mask = BIT(30);
                priv->txdes0_edotr_mask = BIT(30);
                priv->is_aspeed = true;
                /* Disable ast2600 problematic HW arbitration */
                if (of_device_is_compatible(np, "aspeed,ast2600-mac")) {
                        iowrite32(FTGMAC100_TM_DEFAULT,
                                  priv->base + FTGMAC100_OFFSET_TM);
                }
        } else {
                priv->rxdes0_edorr_mask = BIT(15);
                priv->txdes0_edotr_mask = BIT(15);
        }

        if (np && of_get_property(np, "use-ncsi", NULL)) {
                if (!IS_ENABLED(CONFIG_NET_NCSI)) {
                        dev_err(&pdev->dev, "NCSI stack not enabled\n");
                        err = -EINVAL;
                        goto err_phy_connect;
                }

                dev_info(&pdev->dev, "Using NCSI interface\n");
                priv->use_ncsi = true;
                priv->ndev = ncsi_register_dev(netdev, ftgmac100_ncsi_handler);
                if (!priv->ndev) {
                        err = -EINVAL;
                        goto err_phy_connect;
                }
        } else if (np && of_get_property(np, "phy-handle", NULL)) {
                struct phy_device *phy;

                /* Support "mdio"/"phy" child nodes for ast2400/2500 with
                 * an embedded MDIO controller. Automatically scan the DTS for
                 * available PHYs and register them.
                 */
                if (of_device_is_compatible(np, "aspeed,ast2400-mac") ||
                    of_device_is_compatible(np, "aspeed,ast2500-mac")) {
                        err = ftgmac100_setup_mdio(netdev);
                        if (err)
                                goto err_setup_mdio;
                }

                phy = of_phy_get_and_connect(priv->netdev, np,
                                             &ftgmac100_adjust_link);
                if (!phy) {
                        dev_err(&pdev->dev, "Failed to connect to phy\n");
                        err = -EINVAL;
                        goto err_phy_connect;
                }

                /* Indicate that we support PAUSE frames (see comment in
                 * Documentation/networking/phy.rst)
                 */
                phy_support_asym_pause(phy);

                /* Display what we found */
                phy_attached_info(phy);
        } else if (np && !of_get_child_by_name(np, "mdio")) {
                /* Support legacy ASPEED devicetree descriptions that decribe a
                 * MAC with an embedded MDIO controller but have no "mdio"
                 * child node. Automatically scan the MDIO bus for available
                 * PHYs.
                 */
                priv->use_ncsi = false;
                err = ftgmac100_setup_mdio(netdev);
                if (err)
                        goto err_setup_mdio;

                err = ftgmac100_mii_probe(netdev);
                if (err) {
                        dev_err(priv->dev, "MII probe failed!\n");
                        goto err_ncsi_dev;
                }

        }

        if (priv->is_aspeed) {
                err = ftgmac100_setup_clk(priv);
                if (err)
                        goto err_phy_connect;
        }

        /* Default ring sizes */
        priv->rx_q_entries = priv->new_rx_q_entries = DEF_RX_QUEUE_ENTRIES;
        priv->tx_q_entries = priv->new_tx_q_entries = DEF_TX_QUEUE_ENTRIES;

        /* Base feature set */
        netdev->hw_features = NETIF_F_RXCSUM | NETIF_F_HW_CSUM |
                NETIF_F_GRO | NETIF_F_SG | NETIF_F_HW_VLAN_CTAG_RX |
                NETIF_F_HW_VLAN_CTAG_TX;

        if (priv->use_ncsi)
                netdev->hw_features |= NETIF_F_HW_VLAN_CTAG_FILTER;

        /* AST2400  doesn't have working HW checksum generation */
        if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac")))
                netdev->hw_features &= ~NETIF_F_HW_CSUM;
        if (np && of_get_property(np, "no-hw-checksum", NULL))
                netdev->hw_features &= ~(NETIF_F_HW_CSUM | NETIF_F_RXCSUM);
        netdev->features |= netdev->hw_features;

        /* register network device */
        err = register_netdev(netdev);
        if (err) {
                dev_err(&pdev->dev, "Failed to register netdev\n");
                goto err_register_netdev;
        }

        netdev_info(netdev, "irq %d, mapped at %p\n", netdev->irq, priv->base);

        return 0;

err_register_netdev:
        clk_disable_unprepare(priv->rclk);
        clk_disable_unprepare(priv->clk);
err_phy_connect:
        ftgmac100_phy_disconnect(netdev);
err_ncsi_dev:
        if (priv->ndev)
                ncsi_unregister_dev(priv->ndev);
        ftgmac100_destroy_mdio(netdev);
err_setup_mdio:
        iounmap(priv->base);
err_ioremap:
        release_resource(priv->res);
err_req_mem:
        free_netdev(netdev);
err_alloc_etherdev:
        return err;
}

static int ftgmac100_remove(struct platform_device *pdev)
{
        struct net_device *netdev;
        struct ftgmac100 *priv;

        netdev = platform_get_drvdata(pdev);
        priv = netdev_priv(netdev);

        if (priv->ndev)
                ncsi_unregister_dev(priv->ndev);
        unregister_netdev(netdev);

        clk_disable_unprepare(priv->rclk);
        clk_disable_unprepare(priv->clk);

        /* There's a small chance the reset task will have been re-queued,
         * during stop, make sure it's gone before we free the structure.
         */
        cancel_work_sync(&priv->reset_task);

        ftgmac100_phy_disconnect(netdev);
        ftgmac100_destroy_mdio(netdev);

        iounmap(priv->base);
        release_resource(priv->res);

        netif_napi_del(&priv->napi);
        free_netdev(netdev);
        return 0;
}

static const struct of_device_id ftgmac100_of_match[] = {
        { .compatible = "faraday,ftgmac100" },
        { }
};
MODULE_DEVICE_TABLE(of, ftgmac100_of_match);

static struct platform_driver ftgmac100_driver = {
        .probe  = ftgmac100_probe,
        .remove = ftgmac100_remove,
        .driver = {
                .name           = DRV_NAME,
                .of_match_table = ftgmac100_of_match,
        },
};
module_platform_driver(ftgmac100_driver);

MODULE_AUTHOR("Po-Yu Chuang <ratbert@faraday-tech.com>");
MODULE_DESCRIPTION("FTGMAC100 driver");
MODULE_LICENSE("GPL");