// SPDX-License-Identifier: GPL-2.0
/*  Atheros AR71xx built-in ethernet mac driver
 *
 *  Copyright (C) 2019 Oleksij Rempel <o.rempel@pengutronix.de>
 *
 *  List of authors contributed to this driver before mainlining:
 *  Alexander Couzens <lynxis@fe80.eu>
 *  Christian Lamparter <chunkeey@gmail.com>
 *  Chuanhong Guo <gch981213@gmail.com>
 *  Daniel F. Dickinson <cshored@thecshore.com>
 *  David Bauer <mail@david-bauer.net>
 *  Felix Fietkau <nbd@nbd.name>
 *  Gabor Juhos <juhosg@freemail.hu>
 *  Hauke Mehrtens <hauke@hauke-m.de>
 *  Johann Neuhauser <johann@it-neuhauser.de>
 *  John Crispin <john@phrozen.org>
 *  Jo-Philipp Wich <jo@mein.io>
 *  Koen Vandeputte <koen.vandeputte@ncentric.com>
 *  Lucian Cristian <lucian.cristian@gmail.com>
 *  Matt Merhar <mattmerhar@protonmail.com>
 *  Milan Krstic <milan.krstic@gmail.com>
 *  Petr Štetiar <ynezz@true.cz>
 *  Rosen Penev <rosenp@gmail.com>
 *  Stephen Walker <stephendwalker+github@gmail.com>
 *  Vittorio Gambaletta <openwrt@vittgam.net>
 *  Weijie Gao <hackpascal@gmail.com>
 *  Imre Kaloz <kaloz@openwrt.org>
 */

#include <linux/if_vlan.h>
#include <linux/mfd/syscon.h>
#include <linux/of_mdio.h>
#include <linux/of_net.h>
#include <linux/of_platform.h>
#include <linux/phylink.h>
#include <linux/regmap.h>
#include <linux/reset.h>
#include <linux/clk.h>
#include <linux/io.h>

/* For our NAPI weight bigger does *NOT* mean better - it means more
 * D-cache misses and lots more wasted cycles than we'll ever
 * possibly gain from saving instructions.
 */
#define AG71XX_NAPI_WEIGHT      32
#define AG71XX_OOM_REFILL       (1 + HZ / 10)

#define AG71XX_INT_ERR  (AG71XX_INT_RX_BE | AG71XX_INT_TX_BE)
#define AG71XX_INT_TX   (AG71XX_INT_TX_PS)
#define AG71XX_INT_RX   (AG71XX_INT_RX_PR | AG71XX_INT_RX_OF)

#define AG71XX_INT_POLL (AG71XX_INT_RX | AG71XX_INT_TX)
#define AG71XX_INT_INIT (AG71XX_INT_ERR | AG71XX_INT_POLL)

#define AG71XX_TX_MTU_LEN       1540

#define AG71XX_TX_RING_SPLIT            512
#define AG71XX_TX_RING_DS_PER_PKT       DIV_ROUND_UP(AG71XX_TX_MTU_LEN, \
                                                     AG71XX_TX_RING_SPLIT)
#define AG71XX_TX_RING_SIZE_DEFAULT     128
#define AG71XX_RX_RING_SIZE_DEFAULT     256

#define AG71XX_MDIO_RETRY       1000
#define AG71XX_MDIO_DELAY       5
#define AG71XX_MDIO_MAX_CLK     5000000

/* Register offsets */
#define AG71XX_REG_MAC_CFG1     0x0000
#define MAC_CFG1_TXE            BIT(0)  /* Tx Enable */
#define MAC_CFG1_STX            BIT(1)  /* Synchronize Tx Enable */
#define MAC_CFG1_RXE            BIT(2)  /* Rx Enable */
#define MAC_CFG1_SRX            BIT(3)  /* Synchronize Rx Enable */
#define MAC_CFG1_TFC            BIT(4)  /* Tx Flow Control Enable */
#define MAC_CFG1_RFC            BIT(5)  /* Rx Flow Control Enable */
#define MAC_CFG1_SR             BIT(31) /* Soft Reset */
#define MAC_CFG1_INIT   (MAC_CFG1_RXE | MAC_CFG1_TXE | \
                         MAC_CFG1_SRX | MAC_CFG1_STX)

#define AG71XX_REG_MAC_CFG2     0x0004
#define MAC_CFG2_FDX            BIT(0)
#define MAC_CFG2_PAD_CRC_EN     BIT(2)
#define MAC_CFG2_LEN_CHECK      BIT(4)
#define MAC_CFG2_IF_1000        BIT(9)
#define MAC_CFG2_IF_10_100      BIT(8)

#define AG71XX_REG_MAC_MFL      0x0010

#define AG71XX_REG_MII_CFG      0x0020
#define MII_CFG_CLK_DIV_4       0
#define MII_CFG_CLK_DIV_6       2
#define MII_CFG_CLK_DIV_8       3
#define MII_CFG_CLK_DIV_10      4
#define MII_CFG_CLK_DIV_14      5
#define MII_CFG_CLK_DIV_20      6
#define MII_CFG_CLK_DIV_28      7
#define MII_CFG_CLK_DIV_34      8
#define MII_CFG_CLK_DIV_42      9
#define MII_CFG_CLK_DIV_50      10
#define MII_CFG_CLK_DIV_58      11
#define MII_CFG_CLK_DIV_66      12
#define MII_CFG_CLK_DIV_74      13
#define MII_CFG_CLK_DIV_82      14
#define MII_CFG_CLK_DIV_98      15
#define MII_CFG_RESET           BIT(31)

#define AG71XX_REG_MII_CMD      0x0024
#define MII_CMD_READ            BIT(0)

#define AG71XX_REG_MII_ADDR     0x0028
#define MII_ADDR_SHIFT          8

#define AG71XX_REG_MII_CTRL     0x002c
#define AG71XX_REG_MII_STATUS   0x0030
#define AG71XX_REG_MII_IND      0x0034
#define MII_IND_BUSY            BIT(0)
#define MII_IND_INVALID         BIT(2)

#define AG71XX_REG_MAC_IFCTL    0x0038
#define MAC_IFCTL_SPEED         BIT(16)

#define AG71XX_REG_MAC_ADDR1    0x0040
#define AG71XX_REG_MAC_ADDR2    0x0044
#define AG71XX_REG_FIFO_CFG0    0x0048
#define FIFO_CFG0_WTM           BIT(0)  /* Watermark Module */
#define FIFO_CFG0_RXS           BIT(1)  /* Rx System Module */
#define FIFO_CFG0_RXF           BIT(2)  /* Rx Fabric Module */
#define FIFO_CFG0_TXS           BIT(3)  /* Tx System Module */
#define FIFO_CFG0_TXF           BIT(4)  /* Tx Fabric Module */
#define FIFO_CFG0_ALL   (FIFO_CFG0_WTM | FIFO_CFG0_RXS | FIFO_CFG0_RXF \
                        | FIFO_CFG0_TXS | FIFO_CFG0_TXF)
#define FIFO_CFG0_INIT  (FIFO_CFG0_ALL << FIFO_CFG0_ENABLE_SHIFT)

#define FIFO_CFG0_ENABLE_SHIFT  8

#define AG71XX_REG_FIFO_CFG1    0x004c
#define AG71XX_REG_FIFO_CFG2    0x0050
#define AG71XX_REG_FIFO_CFG3    0x0054
#define AG71XX_REG_FIFO_CFG4    0x0058
#define FIFO_CFG4_DE            BIT(0)  /* Drop Event */
#define FIFO_CFG4_DV            BIT(1)  /* RX_DV Event */
#define FIFO_CFG4_FC            BIT(2)  /* False Carrier */
#define FIFO_CFG4_CE            BIT(3)  /* Code Error */
#define FIFO_CFG4_CR            BIT(4)  /* CRC error */
#define FIFO_CFG4_LM            BIT(5)  /* Length Mismatch */
#define FIFO_CFG4_LO            BIT(6)  /* Length out of range */
#define FIFO_CFG4_OK            BIT(7)  /* Packet is OK */
#define FIFO_CFG4_MC            BIT(8)  /* Multicast Packet */
#define FIFO_CFG4_BC            BIT(9)  /* Broadcast Packet */
#define FIFO_CFG4_DR            BIT(10) /* Dribble */
#define FIFO_CFG4_LE            BIT(11) /* Long Event */
#define FIFO_CFG4_CF            BIT(12) /* Control Frame */
#define FIFO_CFG4_PF            BIT(13) /* Pause Frame */
#define FIFO_CFG4_UO            BIT(14) /* Unsupported Opcode */
#define FIFO_CFG4_VT            BIT(15) /* VLAN tag detected */
#define FIFO_CFG4_FT            BIT(16) /* Frame Truncated */
#define FIFO_CFG4_UC            BIT(17) /* Unicast Packet */
#define FIFO_CFG4_INIT  (FIFO_CFG4_DE | FIFO_CFG4_DV | FIFO_CFG4_FC | \
                         FIFO_CFG4_CE | FIFO_CFG4_CR | FIFO_CFG4_LM | \
                         FIFO_CFG4_LO | FIFO_CFG4_OK | FIFO_CFG4_MC | \
                         FIFO_CFG4_BC | FIFO_CFG4_DR | FIFO_CFG4_LE | \
                         FIFO_CFG4_CF | FIFO_CFG4_PF | FIFO_CFG4_UO | \
                         FIFO_CFG4_VT)

#define AG71XX_REG_FIFO_CFG5    0x005c
#define FIFO_CFG5_DE            BIT(0)  /* Drop Event */
#define FIFO_CFG5_DV            BIT(1)  /* RX_DV Event */
#define FIFO_CFG5_FC            BIT(2)  /* False Carrier */
#define FIFO_CFG5_CE            BIT(3)  /* Code Error */
#define FIFO_CFG5_LM            BIT(4)  /* Length Mismatch */
#define FIFO_CFG5_LO            BIT(5)  /* Length Out of Range */
#define FIFO_CFG5_OK            BIT(6)  /* Packet is OK */
#define FIFO_CFG5_MC            BIT(7)  /* Multicast Packet */
#define FIFO_CFG5_BC            BIT(8)  /* Broadcast Packet */
#define FIFO_CFG5_DR            BIT(9)  /* Dribble */
#define FIFO_CFG5_CF            BIT(10) /* Control Frame */
#define FIFO_CFG5_PF            BIT(11) /* Pause Frame */
#define FIFO_CFG5_UO            BIT(12) /* Unsupported Opcode */
#define FIFO_CFG5_VT            BIT(13) /* VLAN tag detected */
#define FIFO_CFG5_LE            BIT(14) /* Long Event */
#define FIFO_CFG5_FT            BIT(15) /* Frame Truncated */
#define FIFO_CFG5_16            BIT(16) /* unknown */
#define FIFO_CFG5_17            BIT(17) /* unknown */
#define FIFO_CFG5_SF            BIT(18) /* Short Frame */
#define FIFO_CFG5_BM            BIT(19) /* Byte Mode */
#define FIFO_CFG5_INIT  (FIFO_CFG5_DE | FIFO_CFG5_DV | FIFO_CFG5_FC | \
                         FIFO_CFG5_CE | FIFO_CFG5_LO | FIFO_CFG5_OK | \
                         FIFO_CFG5_MC | FIFO_CFG5_BC | FIFO_CFG5_DR | \
                         FIFO_CFG5_CF | FIFO_CFG5_PF | FIFO_CFG5_VT | \
                         FIFO_CFG5_LE | FIFO_CFG5_FT | FIFO_CFG5_16 | \
                         FIFO_CFG5_17 | FIFO_CFG5_SF)

#define AG71XX_REG_TX_CTRL      0x0180
#define TX_CTRL_TXE             BIT(0)  /* Tx Enable */

#define AG71XX_REG_TX_DESC      0x0184
#define AG71XX_REG_TX_STATUS    0x0188
#define TX_STATUS_PS            BIT(0)  /* Packet Sent */
#define TX_STATUS_UR            BIT(1)  /* Tx Underrun */
#define TX_STATUS_BE            BIT(3)  /* Bus Error */

#define AG71XX_REG_RX_CTRL      0x018c
#define RX_CTRL_RXE             BIT(0)  /* Rx Enable */

#define AG71XX_DMA_RETRY        10
#define AG71XX_DMA_DELAY        1

#define AG71XX_REG_RX_DESC      0x0190
#define AG71XX_REG_RX_STATUS    0x0194
#define RX_STATUS_PR            BIT(0)  /* Packet Received */
#define RX_STATUS_OF            BIT(2)  /* Rx Overflow */
#define RX_STATUS_BE            BIT(3)  /* Bus Error */

#define AG71XX_REG_INT_ENABLE   0x0198
#define AG71XX_REG_INT_STATUS   0x019c
#define AG71XX_INT_TX_PS        BIT(0)
#define AG71XX_INT_TX_UR        BIT(1)
#define AG71XX_INT_TX_BE        BIT(3)
#define AG71XX_INT_RX_PR        BIT(4)
#define AG71XX_INT_RX_OF        BIT(6)
#define AG71XX_INT_RX_BE        BIT(7)

#define AG71XX_REG_FIFO_DEPTH   0x01a8
#define AG71XX_REG_RX_SM        0x01b0
#define AG71XX_REG_TX_SM        0x01b4

#define ETH_SWITCH_HEADER_LEN   2

#define AG71XX_DEFAULT_MSG_ENABLE       \
        (NETIF_MSG_DRV                  \
        | NETIF_MSG_PROBE               \
        | NETIF_MSG_LINK                \
        | NETIF_MSG_TIMER               \
        | NETIF_MSG_IFDOWN              \
        | NETIF_MSG_IFUP                \
        | NETIF_MSG_RX_ERR              \
        | NETIF_MSG_TX_ERR)

#define DESC_EMPTY              BIT(31)
#define DESC_MORE               BIT(24)
#define DESC_PKTLEN_M           0xfff
struct ag71xx_desc {
        u32 data;
        u32 ctrl;
        u32 next;
        u32 pad;
} __aligned(4);

#define AG71XX_DESC_SIZE        roundup(sizeof(struct ag71xx_desc), \
                                        L1_CACHE_BYTES)

struct ag71xx_buf {
        union {
                struct {
                        struct sk_buff *skb;
                        unsigned int len;
                } tx;
                struct {
                        dma_addr_t dma_addr;
                        void *rx_buf;
                } rx;
        };
};

struct ag71xx_ring {
        /* "Hot" fields in the data path. */
        unsigned int curr;
        unsigned int dirty;

        /* "Cold" fields - not used in the data path. */
        struct ag71xx_buf *buf;
        u16 order;
        u16 desc_split;
        dma_addr_t descs_dma;
        u8 *descs_cpu;
};

enum ag71xx_type {
        AR7100,
        AR7240,
        AR9130,
        AR9330,
        AR9340,
        QCA9530,
        QCA9550,
};

struct ag71xx_dcfg {
        u32 max_frame_len;
        const u32 *fifodata;
        u16 desc_pktlen_mask;
        bool tx_hang_workaround;
        enum ag71xx_type type;
};

struct ag71xx {
        /* Critical data related to the per-packet data path are clustered
         * early in this structure to help improve the D-cache footprint.
         */
        struct ag71xx_ring rx_ring ____cacheline_aligned;
        struct ag71xx_ring tx_ring ____cacheline_aligned;

        u16 rx_buf_size;
        u8 rx_buf_offset;

        struct net_device *ndev;
        struct platform_device *pdev;
        struct napi_struct napi;
        u32 msg_enable;
        const struct ag71xx_dcfg *dcfg;

        /* From this point onwards we're not looking at per-packet fields. */
        void __iomem *mac_base;

        struct ag71xx_desc *stop_desc;
        dma_addr_t stop_desc_dma;

        phy_interface_t phy_if_mode;
        struct phylink *phylink;
        struct phylink_config phylink_config;

        struct delayed_work restart_work;
        struct timer_list oom_timer;

        struct reset_control *mac_reset;

        u32 fifodata[3];
        int mac_idx;

        struct reset_control *mdio_reset;
        struct mii_bus *mii_bus;
        struct clk *clk_mdio;
        struct clk *clk_eth;
};

static int ag71xx_desc_empty(struct ag71xx_desc *desc)
{
        return (desc->ctrl & DESC_EMPTY) != 0;
}

static struct ag71xx_desc *ag71xx_ring_desc(struct ag71xx_ring *ring, int idx)
{
        return (struct ag71xx_desc *)&ring->descs_cpu[idx * AG71XX_DESC_SIZE];
}

static int ag71xx_ring_size_order(int size)
{
        return fls(size - 1);
}

static bool ag71xx_is(struct ag71xx *ag, enum ag71xx_type type)
{
        return ag->dcfg->type == type;
}

static void ag71xx_wr(struct ag71xx *ag, unsigned int reg, u32 value)
{
        iowrite32(value, ag->mac_base + reg);
        /* flush write */
        (void)ioread32(ag->mac_base + reg);
}

static u32 ag71xx_rr(struct ag71xx *ag, unsigned int reg)
{
        return ioread32(ag->mac_base + reg);
}

static void ag71xx_sb(struct ag71xx *ag, unsigned int reg, u32 mask)
{
        void __iomem *r;

        r = ag->mac_base + reg;
        iowrite32(ioread32(r) | mask, r);
        /* flush write */
        (void)ioread32(r);
}

static void ag71xx_cb(struct ag71xx *ag, unsigned int reg, u32 mask)
{
        void __iomem *r;

        r = ag->mac_base + reg;
        iowrite32(ioread32(r) & ~mask, r);
        /* flush write */
        (void)ioread32(r);
}

static void ag71xx_int_enable(struct ag71xx *ag, u32 ints)
{
        ag71xx_sb(ag, AG71XX_REG_INT_ENABLE, ints);
}

static void ag71xx_int_disable(struct ag71xx *ag, u32 ints)
{
        ag71xx_cb(ag, AG71XX_REG_INT_ENABLE, ints);
}

static int ag71xx_mdio_wait_busy(struct ag71xx *ag)
{
        struct net_device *ndev = ag->ndev;
        int i;

        for (i = 0; i < AG71XX_MDIO_RETRY; i++) {
                u32 busy;

                udelay(AG71XX_MDIO_DELAY);

                busy = ag71xx_rr(ag, AG71XX_REG_MII_IND);
                if (!busy)
                        return 0;

                udelay(AG71XX_MDIO_DELAY);
        }

        netif_err(ag, link, ndev, "MDIO operation timed out\n");

        return -ETIMEDOUT;
}

static int ag71xx_mdio_mii_read(struct mii_bus *bus, int addr, int reg)
{
        struct ag71xx *ag = bus->priv;
        int err, val;

        err = ag71xx_mdio_wait_busy(ag);
        if (err)
                return err;

        ag71xx_wr(ag, AG71XX_REG_MII_ADDR,
                  ((addr & 0x1f) << MII_ADDR_SHIFT) | (reg & 0xff));
        /* enable read mode */
        ag71xx_wr(ag, AG71XX_REG_MII_CMD, MII_CMD_READ);

        err = ag71xx_mdio_wait_busy(ag);
        if (err)
                return err;

        val = ag71xx_rr(ag, AG71XX_REG_MII_STATUS);
        /* disable read mode */
        ag71xx_wr(ag, AG71XX_REG_MII_CMD, 0);

        netif_dbg(ag, link, ag->ndev, "mii_read: addr=%04x, reg=%04x, value=%04x\n",
                  addr, reg, val);

        return val;
}

static int ag71xx_mdio_mii_write(struct mii_bus *bus, int addr, int reg,
                                 u16 val)
{
        struct ag71xx *ag = bus->priv;

        netif_dbg(ag, link, ag->ndev, "mii_write: addr=%04x, reg=%04x, value=%04x\n",
                  addr, reg, val);

        ag71xx_wr(ag, AG71XX_REG_MII_ADDR,
                  ((addr & 0x1f) << MII_ADDR_SHIFT) | (reg & 0xff));
        ag71xx_wr(ag, AG71XX_REG_MII_CTRL, val);

        return ag71xx_mdio_wait_busy(ag);
}

static const u32 ar71xx_mdio_div_table[] = {
        4, 4, 6, 8, 10, 14, 20, 28,
};

static const u32 ar7240_mdio_div_table[] = {
        2, 2, 4, 6, 8, 12, 18, 26, 32, 40, 48, 56, 62, 70, 78, 96,
};

static const u32 ar933x_mdio_div_table[] = {
        4, 4, 6, 8, 10, 14, 20, 28, 34, 42, 50, 58, 66, 74, 82, 98,
};

static int ag71xx_mdio_get_divider(struct ag71xx *ag, u32 *div)
{
        unsigned long ref_clock;
        const u32 *table;
        int ndivs, i;

        ref_clock = clk_get_rate(ag->clk_mdio);
        if (!ref_clock)
                return -EINVAL;

        if (ag71xx_is(ag, AR9330) || ag71xx_is(ag, AR9340)) {
                table = ar933x_mdio_div_table;
                ndivs = ARRAY_SIZE(ar933x_mdio_div_table);
        } else if (ag71xx_is(ag, AR7240)) {
                table = ar7240_mdio_div_table;
                ndivs = ARRAY_SIZE(ar7240_mdio_div_table);
        } else {
                table = ar71xx_mdio_div_table;
                ndivs = ARRAY_SIZE(ar71xx_mdio_div_table);
        }

        for (i = 0; i < ndivs; i++) {
                unsigned long t;

                t = ref_clock / table[i];
                if (t <= AG71XX_MDIO_MAX_CLK) {
                        *div = i;
                        return 0;
                }
        }

        return -ENOENT;
}

static int ag71xx_mdio_reset(struct mii_bus *bus)
{
        struct ag71xx *ag = bus->priv;
        int err;
        u32 t;

        err = ag71xx_mdio_get_divider(ag, &t);
        if (err)
                return err;

        ag71xx_wr(ag, AG71XX_REG_MII_CFG, t | MII_CFG_RESET);
        usleep_range(100, 200);

        ag71xx_wr(ag, AG71XX_REG_MII_CFG, t);
        usleep_range(100, 200);

        return 0;
}

static int ag71xx_mdio_probe(struct ag71xx *ag)
{
        struct device *dev = &ag->pdev->dev;
        struct net_device *ndev = ag->ndev;
        static struct mii_bus *mii_bus;
        struct device_node *np, *mnp;
        int err;

        np = dev->of_node;
        ag->mii_bus = NULL;

        ag->clk_mdio = devm_clk_get(dev, "mdio");
        if (IS_ERR(ag->clk_mdio)) {
                netif_err(ag, probe, ndev, "Failed to get mdio clk.\n");
                return PTR_ERR(ag->clk_mdio);
        }

        err = clk_prepare_enable(ag->clk_mdio);
        if (err) {
                netif_err(ag, probe, ndev, "Failed to enable mdio clk.\n");
                return err;
        }

        mii_bus = devm_mdiobus_alloc(dev);
        if (!mii_bus) {
                err = -ENOMEM;
                goto mdio_err_put_clk;
        }

        ag->mdio_reset = of_reset_control_get_exclusive(np, "mdio");
        if (IS_ERR(ag->mdio_reset)) {
                netif_err(ag, probe, ndev, "Failed to get reset mdio.\n");
                err = PTR_ERR(ag->mdio_reset);
                goto mdio_err_put_clk;
        }

        mii_bus->name = "ag71xx_mdio";
        mii_bus->read = ag71xx_mdio_mii_read;
        mii_bus->write = ag71xx_mdio_mii_write;
        mii_bus->reset = ag71xx_mdio_reset;
        mii_bus->priv = ag;
        mii_bus->parent = dev;
        snprintf(mii_bus->id, MII_BUS_ID_SIZE, "%s.%d", np->name, ag->mac_idx);

        if (!IS_ERR(ag->mdio_reset)) {
                reset_control_assert(ag->mdio_reset);
                msleep(100);
                reset_control_deassert(ag->mdio_reset);
                msleep(200);
        }

        mnp = of_get_child_by_name(np, "mdio");
        err = of_mdiobus_register(mii_bus, mnp);
        of_node_put(mnp);
        if (err)
                goto mdio_err_put_clk;

        ag->mii_bus = mii_bus;

        return 0;

mdio_err_put_clk:
        clk_disable_unprepare(ag->clk_mdio);
        return err;
}

static void ag71xx_mdio_remove(struct ag71xx *ag)
{
        if (ag->mii_bus)
                mdiobus_unregister(ag->mii_bus);
        clk_disable_unprepare(ag->clk_mdio);
}

static void ag71xx_hw_stop(struct ag71xx *ag)
{
        /* disable all interrupts and stop the rx/tx engine */
        ag71xx_wr(ag, AG71XX_REG_INT_ENABLE, 0);
        ag71xx_wr(ag, AG71XX_REG_RX_CTRL, 0);
        ag71xx_wr(ag, AG71XX_REG_TX_CTRL, 0);
}

static bool ag71xx_check_dma_stuck(struct ag71xx *ag)
{
        unsigned long timestamp;
        u32 rx_sm, tx_sm, rx_fd;

        timestamp = netdev_get_tx_queue(ag->ndev, 0)->trans_start;
        if (likely(time_before(jiffies, timestamp + HZ / 10)))
                return false;

        if (!netif_carrier_ok(ag->ndev))
                return false;

        rx_sm = ag71xx_rr(ag, AG71XX_REG_RX_SM);
        if ((rx_sm & 0x7) == 0x3 && ((rx_sm >> 4) & 0x7) == 0x6)
                return true;

        tx_sm = ag71xx_rr(ag, AG71XX_REG_TX_SM);
        rx_fd = ag71xx_rr(ag, AG71XX_REG_FIFO_DEPTH);
        if (((tx_sm >> 4) & 0x7) == 0 && ((rx_sm & 0x7) == 0) &&
            ((rx_sm >> 4) & 0x7) == 0 && rx_fd == 0)
                return true;

        return false;
}

static int ag71xx_tx_packets(struct ag71xx *ag, bool flush)
{
        struct ag71xx_ring *ring = &ag->tx_ring;
        int sent = 0, bytes_compl = 0, n = 0;
        struct net_device *ndev = ag->ndev;
        int ring_mask, ring_size;
        bool dma_stuck = false;

        ring_mask = BIT(ring->order) - 1;
        ring_size = BIT(ring->order);

        netif_dbg(ag, tx_queued, ndev, "processing TX ring\n");

        while (ring->dirty + n != ring->curr) {
                struct ag71xx_desc *desc;
                struct sk_buff *skb;
                unsigned int i;

                i = (ring->dirty + n) & ring_mask;
                desc = ag71xx_ring_desc(ring, i);
                skb = ring->buf[i].tx.skb;

                if (!flush && !ag71xx_desc_empty(desc)) {
                        if (ag->dcfg->tx_hang_workaround &&
                            ag71xx_check_dma_stuck(ag)) {
                                schedule_delayed_work(&ag->restart_work,
                                                      HZ / 2);
                                dma_stuck = true;
                        }
                        break;
                }

                if (flush)
                        desc->ctrl |= DESC_EMPTY;

                n++;
                if (!skb)
                        continue;

                dev_kfree_skb_any(skb);
                ring->buf[i].tx.skb = NULL;

                bytes_compl += ring->buf[i].tx.len;

                sent++;
                ring->dirty += n;

                while (n > 0) {
                        ag71xx_wr(ag, AG71XX_REG_TX_STATUS, TX_STATUS_PS);
                        n--;
                }
        }

        netif_dbg(ag, tx_done, ndev, "%d packets sent out\n", sent);

        if (!sent)
                return 0;

        ag->ndev->stats.tx_bytes += bytes_compl;
        ag->ndev->stats.tx_packets += sent;

        netdev_completed_queue(ag->ndev, sent, bytes_compl);
        if ((ring->curr - ring->dirty) < (ring_size * 3) / 4)
                netif_wake_queue(ag->ndev);

        if (!dma_stuck)
                cancel_delayed_work(&ag->restart_work);

        return sent;
}

static void ag71xx_dma_wait_stop(struct ag71xx *ag)
{
        struct net_device *ndev = ag->ndev;
        int i;

        for (i = 0; i < AG71XX_DMA_RETRY; i++) {
                u32 rx, tx;

                mdelay(AG71XX_DMA_DELAY);

                rx = ag71xx_rr(ag, AG71XX_REG_RX_CTRL) & RX_CTRL_RXE;
                tx = ag71xx_rr(ag, AG71XX_REG_TX_CTRL) & TX_CTRL_TXE;
                if (!rx && !tx)
                        return;
        }

        netif_err(ag, hw, ndev, "DMA stop operation timed out\n");
}

static void ag71xx_dma_reset(struct ag71xx *ag)
{
        struct net_device *ndev = ag->ndev;
        u32 val;
        int i;

        /* stop RX and TX */
        ag71xx_wr(ag, AG71XX_REG_RX_CTRL, 0);
        ag71xx_wr(ag, AG71XX_REG_TX_CTRL, 0);

        /* give the hardware some time to really stop all rx/tx activity
         * clearing the descriptors too early causes random memory corruption
         */
        ag71xx_dma_wait_stop(ag);

        /* clear descriptor addresses */
        ag71xx_wr(ag, AG71XX_REG_TX_DESC, ag->stop_desc_dma);
        ag71xx_wr(ag, AG71XX_REG_RX_DESC, ag->stop_desc_dma);

        /* clear pending RX/TX interrupts */
        for (i = 0; i < 256; i++) {
                ag71xx_wr(ag, AG71XX_REG_RX_STATUS, RX_STATUS_PR);
                ag71xx_wr(ag, AG71XX_REG_TX_STATUS, TX_STATUS_PS);
        }

        /* clear pending errors */
        ag71xx_wr(ag, AG71XX_REG_RX_STATUS, RX_STATUS_BE | RX_STATUS_OF);
        ag71xx_wr(ag, AG71XX_REG_TX_STATUS, TX_STATUS_BE | TX_STATUS_UR);

        val = ag71xx_rr(ag, AG71XX_REG_RX_STATUS);
        if (val)
                netif_err(ag, hw, ndev, "unable to clear DMA Rx status: %08x\n",
                          val);

        val = ag71xx_rr(ag, AG71XX_REG_TX_STATUS);

        /* mask out reserved bits */
        val &= ~0xff000000;

        if (val)
                netif_err(ag, hw, ndev, "unable to clear DMA Tx status: %08x\n",
                          val);
}

static void ag71xx_hw_setup(struct ag71xx *ag)
{
        u32 init = MAC_CFG1_INIT;

        /* setup MAC configuration registers */
        ag71xx_wr(ag, AG71XX_REG_MAC_CFG1, init);

        ag71xx_sb(ag, AG71XX_REG_MAC_CFG2,
                  MAC_CFG2_PAD_CRC_EN | MAC_CFG2_LEN_CHECK);

        /* setup max frame length to zero */
        ag71xx_wr(ag, AG71XX_REG_MAC_MFL, 0);

        /* setup FIFO configuration registers */
        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG0, FIFO_CFG0_INIT);
        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG1, ag->fifodata[0]);
        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG2, ag->fifodata[1]);
        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG4, FIFO_CFG4_INIT);
        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG5, FIFO_CFG5_INIT);
}

static unsigned int ag71xx_max_frame_len(unsigned int mtu)
{
        return ETH_SWITCH_HEADER_LEN + ETH_HLEN + VLAN_HLEN + mtu + ETH_FCS_LEN;
}

static void ag71xx_hw_set_macaddr(struct ag71xx *ag, unsigned char *mac)
{
        u32 t;

        t = (((u32)mac[5]) << 24) | (((u32)mac[4]) << 16)
          | (((u32)mac[3]) << 8) | ((u32)mac[2]);

        ag71xx_wr(ag, AG71XX_REG_MAC_ADDR1, t);

        t = (((u32)mac[1]) << 24) | (((u32)mac[0]) << 16);
        ag71xx_wr(ag, AG71XX_REG_MAC_ADDR2, t);
}

static void ag71xx_fast_reset(struct ag71xx *ag)
{
        struct net_device *dev = ag->ndev;
        u32 rx_ds;
        u32 mii_reg;

        ag71xx_hw_stop(ag);

        mii_reg = ag71xx_rr(ag, AG71XX_REG_MII_CFG);
        rx_ds = ag71xx_rr(ag, AG71XX_REG_RX_DESC);

        ag71xx_tx_packets(ag, true);

        reset_control_assert(ag->mac_reset);
        usleep_range(10, 20);
        reset_control_deassert(ag->mac_reset);
        usleep_range(10, 20);

        ag71xx_dma_reset(ag);
        ag71xx_hw_setup(ag);
        ag->tx_ring.curr = 0;
        ag->tx_ring.dirty = 0;
        netdev_reset_queue(ag->ndev);

        /* setup max frame length */
        ag71xx_wr(ag, AG71XX_REG_MAC_MFL,
                  ag71xx_max_frame_len(ag->ndev->mtu));

        ag71xx_wr(ag, AG71XX_REG_RX_DESC, rx_ds);
        ag71xx_wr(ag, AG71XX_REG_TX_DESC, ag->tx_ring.descs_dma);
        ag71xx_wr(ag, AG71XX_REG_MII_CFG, mii_reg);

        ag71xx_hw_set_macaddr(ag, dev->dev_addr);
}

static void ag71xx_hw_start(struct ag71xx *ag)
{
        /* start RX engine */
        ag71xx_wr(ag, AG71XX_REG_RX_CTRL, RX_CTRL_RXE);

        /* enable interrupts */
        ag71xx_wr(ag, AG71XX_REG_INT_ENABLE, AG71XX_INT_INIT);

        netif_wake_queue(ag->ndev);
}

static void ag71xx_mac_config(struct phylink_config *config, unsigned int mode,
                              const struct phylink_link_state *state)
{
        struct ag71xx *ag = netdev_priv(to_net_dev(config->dev));

        if (phylink_autoneg_inband(mode))
                return;

        if (!ag71xx_is(ag, AR7100) && !ag71xx_is(ag, AR9130))
                ag71xx_fast_reset(ag);

        if (ag->tx_ring.desc_split) {
                ag->fifodata[2] &= 0xffff;
                ag->fifodata[2] |= ((2048 - ag->tx_ring.desc_split) / 4) << 16;
        }

        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG3, ag->fifodata[2]);
}

static void ag71xx_mac_validate(struct phylink_config *config,
                            unsigned long *supported,
                            struct phylink_link_state *state)
{
        struct ag71xx *ag = netdev_priv(to_net_dev(config->dev));
        __ETHTOOL_DECLARE_LINK_MODE_MASK(mask) = { 0, };

        switch (state->interface) {
        case PHY_INTERFACE_MODE_NA:
                break;
        case PHY_INTERFACE_MODE_MII:
                if ((ag71xx_is(ag, AR9330) && ag->mac_idx == 0) ||
                    ag71xx_is(ag, AR9340) ||
                    ag71xx_is(ag, QCA9530) ||
                    (ag71xx_is(ag, QCA9550) && ag->mac_idx == 1))
                        break;
                goto unsupported;
        case PHY_INTERFACE_MODE_GMII:
                if ((ag71xx_is(ag, AR9330) && ag->mac_idx == 1) ||
                    (ag71xx_is(ag, AR9340) && ag->mac_idx == 1) ||
                    (ag71xx_is(ag, QCA9530) && ag->mac_idx == 1))
                        break;
                goto unsupported;
        case PHY_INTERFACE_MODE_SGMII:
                if (ag71xx_is(ag, QCA9550) && ag->mac_idx == 0)
                        break;
                goto unsupported;
        case PHY_INTERFACE_MODE_RMII:
                if (ag71xx_is(ag, AR9340) && ag->mac_idx == 0)
                        break;
                goto unsupported;
        case PHY_INTERFACE_MODE_RGMII:
                if ((ag71xx_is(ag, AR9340) && ag->mac_idx == 0) ||
                    (ag71xx_is(ag, QCA9550) && ag->mac_idx == 1))
                        break;
                goto unsupported;
        default:
                goto unsupported;
        }

        phylink_set(mask, MII);

        phylink_set(mask, Autoneg);
        phylink_set(mask, 10baseT_Half);
        phylink_set(mask, 10baseT_Full);
        phylink_set(mask, 100baseT_Half);
        phylink_set(mask, 100baseT_Full);

        if (state->interface == PHY_INTERFACE_MODE_NA ||
            state->interface == PHY_INTERFACE_MODE_SGMII ||
            state->interface == PHY_INTERFACE_MODE_RGMII ||
            state->interface == PHY_INTERFACE_MODE_GMII) {
                phylink_set(mask, 1000baseT_Full);
                phylink_set(mask, 1000baseX_Full);
        }

        bitmap_and(supported, supported, mask,
                   __ETHTOOL_LINK_MODE_MASK_NBITS);
        bitmap_and(state->advertising, state->advertising, mask,
                   __ETHTOOL_LINK_MODE_MASK_NBITS);

        return;
unsupported:
        bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
}

static void ag71xx_mac_pcs_get_state(struct phylink_config *config,
                                     struct phylink_link_state *state)
{
        state->link = 0;
}

static void ag71xx_mac_an_restart(struct phylink_config *config)
{
        /* Not Supported */
}

static void ag71xx_mac_link_down(struct phylink_config *config,
                                 unsigned int mode, phy_interface_t interface)
{
        struct ag71xx *ag = netdev_priv(to_net_dev(config->dev));

        ag71xx_hw_stop(ag);
}

static void ag71xx_mac_link_up(struct phylink_config *config,
                               struct phy_device *phy,
                               unsigned int mode, phy_interface_t interface,
                               int speed, int duplex,
                               bool tx_pause, bool rx_pause)
{
        struct ag71xx *ag = netdev_priv(to_net_dev(config->dev));
        u32 cfg2;
        u32 ifctl;
        u32 fifo5;

        cfg2 = ag71xx_rr(ag, AG71XX_REG_MAC_CFG2);
        cfg2 &= ~(MAC_CFG2_IF_1000 | MAC_CFG2_IF_10_100 | MAC_CFG2_FDX);
        cfg2 |= duplex ? MAC_CFG2_FDX : 0;

        ifctl = ag71xx_rr(ag, AG71XX_REG_MAC_IFCTL);
        ifctl &= ~(MAC_IFCTL_SPEED);

        fifo5 = ag71xx_rr(ag, AG71XX_REG_FIFO_CFG5);
        fifo5 &= ~FIFO_CFG5_BM;

        switch (speed) {
        case SPEED_1000:
                cfg2 |= MAC_CFG2_IF_1000;
                fifo5 |= FIFO_CFG5_BM;
                break;
        case SPEED_100:
                cfg2 |= MAC_CFG2_IF_10_100;
                ifctl |= MAC_IFCTL_SPEED;
                break;
        case SPEED_10:
                cfg2 |= MAC_CFG2_IF_10_100;
                break;
        default:
                return;
        }

        ag71xx_wr(ag, AG71XX_REG_MAC_CFG2, cfg2);
        ag71xx_wr(ag, AG71XX_REG_FIFO_CFG5, fifo5);
        ag71xx_wr(ag, AG71XX_REG_MAC_IFCTL, ifctl);

        ag71xx_hw_start(ag);
}

static const struct phylink_mac_ops ag71xx_phylink_mac_ops = {

        .validate = ag71xx_mac_validate,
        .mac_pcs_get_state = ag71xx_mac_pcs_get_state,
        .mac_an_restart = ag71xx_mac_an_restart,
        .mac_config = ag71xx_mac_config,
        .mac_link_down = ag71xx_mac_link_down,
        .mac_link_up = ag71xx_mac_link_up,
};

static int ag71xx_phylink_setup(struct ag71xx *ag)
{
        struct phylink *phylink;

        ag->phylink_config.dev = &ag->ndev->dev;
        ag->phylink_config.type = PHYLINK_NETDEV;

        phylink = phylink_create(&ag->phylink_config, ag->pdev->dev.fwnode,
                                 ag->phy_if_mode, &ag71xx_phylink_mac_ops);
        if (IS_ERR(phylink))
                return PTR_ERR(phylink);

        ag->phylink = phylink;
        return 0;
}

static void ag71xx_ring_tx_clean(struct ag71xx *ag)
{
        struct ag71xx_ring *ring = &ag->tx_ring;
        int ring_mask = BIT(ring->order) - 1;
        u32 bytes_compl = 0, pkts_compl = 0;
        struct net_device *ndev = ag->ndev;

        while (ring->curr != ring->dirty) {
                struct ag71xx_desc *desc;
                u32 i = ring->dirty & ring_mask;

                desc = ag71xx_ring_desc(ring, i);
                if (!ag71xx_desc_empty(desc)) {
                        desc->ctrl = 0;
                        ndev->stats.tx_errors++;
                }

                if (ring->buf[i].tx.skb) {
                        bytes_compl += ring->buf[i].tx.len;
                        pkts_compl++;
                        dev_kfree_skb_any(ring->buf[i].tx.skb);
                }
                ring->buf[i].tx.skb = NULL;
                ring->dirty++;
        }

        /* flush descriptors */
        wmb();

        netdev_completed_queue(ndev, pkts_compl, bytes_compl);
}

static void ag71xx_ring_tx_init(struct ag71xx *ag)
{
        struct ag71xx_ring *ring = &ag->tx_ring;
        int ring_size = BIT(ring->order);
        int ring_mask = ring_size - 1;
        int i;

        for (i = 0; i < ring_size; i++) {
                struct ag71xx_desc *desc = ag71xx_ring_desc(ring, i);

                desc->next = (u32)(ring->descs_dma +
                        AG71XX_DESC_SIZE * ((i + 1) & ring_mask));

                desc->ctrl = DESC_EMPTY;
                ring->buf[i].tx.skb = NULL;
        }

        /* flush descriptors */
        wmb();

        ring->curr = 0;
        ring->dirty = 0;
        netdev_reset_queue(ag->ndev);
}

static void ag71xx_ring_rx_clean(struct ag71xx *ag)
{
        struct ag71xx_ring *ring = &ag->rx_ring;
        int ring_size = BIT(ring->order);
        int i;

        if (!ring->buf)
                return;

        for (i = 0; i < ring_size; i++)
                if (ring->buf[i].rx.rx_buf) {
                        dma_unmap_single(&ag->pdev->dev,
                                         ring->buf[i].rx.dma_addr,
                                         ag->rx_buf_size, DMA_FROM_DEVICE);
                        skb_free_frag(ring->buf[i].rx.rx_buf);
                }
}

static int ag71xx_buffer_size(struct ag71xx *ag)
{
        return ag->rx_buf_size +
               SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
}

static bool ag71xx_fill_rx_buf(struct ag71xx *ag, struct ag71xx_buf *buf,
                               int offset,
                               void *(*alloc)(unsigned int size))
{
        struct ag71xx_ring *ring = &ag->rx_ring;
        struct ag71xx_desc *desc;
        void *data;

        desc = ag71xx_ring_desc(ring, buf - &ring->buf[0]);

        data = alloc(ag71xx_buffer_size(ag));
        if (!data)
                return false;

        buf->rx.rx_buf = data;
        buf->rx.dma_addr = dma_map_single(&ag->pdev->dev, data, ag->rx_buf_size,
                                          DMA_FROM_DEVICE);
        desc->data = (u32)buf->rx.dma_addr + offset;
        return true;
}

static int ag71xx_ring_rx_init(struct ag71xx *ag)
{
        struct ag71xx_ring *ring = &ag->rx_ring;
        struct net_device *ndev = ag->ndev;
        int ring_mask = BIT(ring->order) - 1;
        int ring_size = BIT(ring->order);
        unsigned int i;
        int ret;

        ret = 0;
        for (i = 0; i < ring_size; i++) {
                struct ag71xx_desc *desc = ag71xx_ring_desc(ring, i);

                desc->next = (u32)(ring->descs_dma +
                        AG71XX_DESC_SIZE * ((i + 1) & ring_mask));

                netif_dbg(ag, rx_status, ndev, "RX desc at %p, next is %08x\n",
                          desc, desc->next);
        }

        for (i = 0; i < ring_size; i++) {
                struct ag71xx_desc *desc = ag71xx_ring_desc(ring, i);

                if (!ag71xx_fill_rx_buf(ag, &ring->buf[i], ag->rx_buf_offset,
                                        netdev_alloc_frag)) {
                        ret = -ENOMEM;
                        break;
                }

                desc->ctrl = DESC_EMPTY;
        }

        /* flush descriptors */
        wmb();

        ring->curr = 0;
        ring->dirty = 0;

        return ret;
}

static int ag71xx_ring_rx_refill(struct ag71xx *ag)
{
        struct ag71xx_ring *ring = &ag->rx_ring;
        int ring_mask = BIT(ring->order) - 1;
        int offset = ag->rx_buf_offset;
        unsigned int count;

        count = 0;
        for (; ring->curr - ring->dirty > 0; ring->dirty++) {
                struct ag71xx_desc *desc;
                unsigned int i;

                i = ring->dirty & ring_mask;
                desc = ag71xx_ring_desc(ring, i);

                if (!ring->buf[i].rx.rx_buf &&
                    !ag71xx_fill_rx_buf(ag, &ring->buf[i], offset,
                                        napi_alloc_frag))
                        break;

                desc->ctrl = DESC_EMPTY;
                count++;
        }

        /* flush descriptors */
        wmb();

        netif_dbg(ag, rx_status, ag->ndev, "%u rx descriptors refilled\n",
                  count);

        return count;
}

static int ag71xx_rings_init(struct ag71xx *ag)
{
        struct ag71xx_ring *tx = &ag->tx_ring;
        struct ag71xx_ring *rx = &ag->rx_ring;
        int ring_size, tx_size;

        ring_size = BIT(tx->order) + BIT(rx->order);
        tx_size = BIT(tx->order);

        tx->buf = kcalloc(ring_size, sizeof(*tx->buf), GFP_KERNEL);
        if (!tx->buf)
                return -ENOMEM;

        tx->descs_cpu = dma_alloc_coherent(&ag->pdev->dev,
                                           ring_size * AG71XX_DESC_SIZE,
                                           &tx->descs_dma, GFP_KERNEL);
        if (!tx->descs_cpu) {
                kfree(tx->buf);
                tx->buf = NULL;
                return -ENOMEM;
        }

        rx->buf = &tx->buf[tx_size];
        rx->descs_cpu = ((void *)tx->descs_cpu) + tx_size * AG71XX_DESC_SIZE;
        rx->descs_dma = tx->descs_dma + tx_size * AG71XX_DESC_SIZE;

        ag71xx_ring_tx_init(ag);
        return ag71xx_ring_rx_init(ag);
}

static void ag71xx_rings_free(struct ag71xx *ag)
{
        struct ag71xx_ring *tx = &ag->tx_ring;
        struct ag71xx_ring *rx = &ag->rx_ring;
        int ring_size;

        ring_size = BIT(tx->order) + BIT(rx->order);

        if (tx->descs_cpu)
                dma_free_coherent(&ag->pdev->dev, ring_size * AG71XX_DESC_SIZE,
                                  tx->descs_cpu, tx->descs_dma);

        kfree(tx->buf);

        tx->descs_cpu = NULL;
        rx->descs_cpu = NULL;
        tx->buf = NULL;
        rx->buf = NULL;
}

static void ag71xx_rings_cleanup(struct ag71xx *ag)
{
        ag71xx_ring_rx_clean(ag);
        ag71xx_ring_tx_clean(ag);
        ag71xx_rings_free(ag);

        netdev_reset_queue(ag->ndev);
}

static void ag71xx_hw_init(struct ag71xx *ag)
{
        ag71xx_hw_stop(ag);

        ag71xx_sb(ag, AG71XX_REG_MAC_CFG1, MAC_CFG1_SR);
        usleep_range(20, 30);

        reset_control_assert(ag->mac_reset);
        msleep(100);
        reset_control_deassert(ag->mac_reset);
        msleep(200);

        ag71xx_hw_setup(ag);

        ag71xx_dma_reset(ag);
}

static int ag71xx_hw_enable(struct ag71xx *ag)
{
        int ret;

        ret = ag71xx_rings_init(ag);
        if (ret)
                return ret;

        napi_enable(&ag->napi);
        ag71xx_wr(ag, AG71XX_REG_TX_DESC, ag->tx_ring.descs_dma);
        ag71xx_wr(ag, AG71XX_REG_RX_DESC, ag->rx_ring.descs_dma);
        netif_start_queue(ag->ndev);

        return 0;
}

static void ag71xx_hw_disable(struct ag71xx *ag)
{
        netif_stop_queue(ag->ndev);

        ag71xx_hw_stop(ag);
        ag71xx_dma_reset(ag);

        napi_disable(&ag->napi);
        del_timer_sync(&ag->oom_timer);

        ag71xx_rings_cleanup(ag);
}

static int ag71xx_open(struct net_device *ndev)
{
        struct ag71xx *ag = netdev_priv(ndev);
        unsigned int max_frame_len;
        int ret;

        ret = phylink_of_phy_connect(ag->phylink, ag->pdev->dev.of_node, 0);
        if (ret) {
                netif_err(ag, link, ndev, "phylink_of_phy_connect filed with err: %i\n",
                          ret);
                goto err;
        }

        max_frame_len = ag71xx_max_frame_len(ndev->mtu);
        ag->rx_buf_size =
                SKB_DATA_ALIGN(max_frame_len + NET_SKB_PAD + NET_IP_ALIGN);

        /* setup max frame length */
        ag71xx_wr(ag, AG71XX_REG_MAC_MFL, max_frame_len);
        ag71xx_hw_set_macaddr(ag, ndev->dev_addr);

        ret = ag71xx_hw_enable(ag);
        if (ret)
                goto err;

        phylink_start(ag->phylink);

        return 0;

err:
        ag71xx_rings_cleanup(ag);
        return ret;
}

static int ag71xx_stop(struct net_device *ndev)
{
        struct ag71xx *ag = netdev_priv(ndev);

        phylink_stop(ag->phylink);
        phylink_disconnect_phy(ag->phylink);
        ag71xx_hw_disable(ag);

        return 0;
}

static int ag71xx_fill_dma_desc(struct ag71xx_ring *ring, u32 addr, int len)
{
        int i, ring_mask, ndesc, split;
        struct ag71xx_desc *desc;

        ring_mask = BIT(ring->order) - 1;
        ndesc = 0;
        split = ring->desc_split;

        if (!split)
                split = len;

        while (len > 0) {
                unsigned int cur_len = len;

                i = (ring->curr + ndesc) & ring_mask;
                desc = ag71xx_ring_desc(ring, i);

                if (!ag71xx_desc_empty(desc))
                        return -1;

                if (cur_len > split) {
                        cur_len = split;

                        /*  TX will hang if DMA transfers <= 4 bytes,
                         * make sure next segment is more than 4 bytes long.
                         */
                        if (len <= split + 4)
                                cur_len -= 4;
                }

                desc->data = addr;
                addr += cur_len;
                len -= cur_len;

                if (len > 0)
                        cur_len |= DESC_MORE;

                /* prevent early tx attempt of this descriptor */
                if (!ndesc)
                        cur_len |= DESC_EMPTY;

                desc->ctrl = cur_len;
                ndesc++;
        }

        return ndesc;
}

static netdev_tx_t ag71xx_hard_start_xmit(struct sk_buff *skb,
                                          struct net_device *ndev)
{
        int i, n, ring_min, ring_mask, ring_size;
        struct ag71xx *ag = netdev_priv(ndev);
        struct ag71xx_ring *ring;
        struct ag71xx_desc *desc;
        dma_addr_t dma_addr;

        ring = &ag->tx_ring;
        ring_mask = BIT(ring->order) - 1;
        ring_size = BIT(ring->order);

        if (skb->len <= 4) {
                netif_dbg(ag, tx_err, ndev, "packet len is too small\n");
                goto err_drop;
        }

        dma_addr = dma_map_single(&ag->pdev->dev, skb->data, skb->len,
                                  DMA_TO_DEVICE);

        i = ring->curr & ring_mask;
        desc = ag71xx_ring_desc(ring, i);

        /* setup descriptor fields */
        n = ag71xx_fill_dma_desc(ring, (u32)dma_addr,
                                 skb->len & ag->dcfg->desc_pktlen_mask);
        if (n < 0)
                goto err_drop_unmap;

        i = (ring->curr + n - 1) & ring_mask;
        ring->buf[i].tx.len = skb->len;
        ring->buf[i].tx.skb = skb;

        netdev_sent_queue(ndev, skb->len);

        skb_tx_timestamp(skb);

        desc->ctrl &= ~DESC_EMPTY;
        ring->curr += n;

        /* flush descriptor */
        wmb();

        ring_min = 2;
        if (ring->desc_split)
                ring_min *= AG71XX_TX_RING_DS_PER_PKT;

        if (ring->curr - ring->dirty >= ring_size - ring_min) {
                netif_dbg(ag, tx_err, ndev, "tx queue full\n");
                netif_stop_queue(ndev);
        }

        netif_dbg(ag, tx_queued, ndev, "packet injected into TX queue\n");

        /* enable TX engine */
        ag71xx_wr(ag, AG71XX_REG_TX_CTRL, TX_CTRL_TXE);

        return NETDEV_TX_OK;

err_drop_unmap:
        dma_unmap_single(&ag->pdev->dev, dma_addr, skb->len, DMA_TO_DEVICE);

err_drop:
        ndev->stats.tx_dropped++;

        dev_kfree_skb(skb);
        return NETDEV_TX_OK;
}

static void ag71xx_oom_timer_handler(struct timer_list *t)
{
        struct ag71xx *ag = from_timer(ag, t, oom_timer);

        napi_schedule(&ag->napi);
}

static void ag71xx_tx_timeout(struct net_device *ndev, unsigned int txqueue)
{
        struct ag71xx *ag = netdev_priv(ndev);

        netif_err(ag, tx_err, ndev, "tx timeout\n");

        schedule_delayed_work(&ag->restart_work, 1);
}

static void ag71xx_restart_work_func(struct work_struct *work)
{
        struct ag71xx *ag = container_of(work, struct ag71xx,
                                         restart_work.work);

        rtnl_lock();
        ag71xx_hw_disable(ag);
        ag71xx_hw_enable(ag);

        phylink_stop(ag->phylink);
        phylink_start(ag->phylink);

        rtnl_unlock();
}

static int ag71xx_rx_packets(struct ag71xx *ag, int limit)
{
        struct net_device *ndev = ag->ndev;
        int ring_mask, ring_size, done = 0;
        unsigned int pktlen_mask, offset;
        struct sk_buff *next, *skb;
        struct ag71xx_ring *ring;
        struct list_head rx_list;

        ring = &ag->rx_ring;
        pktlen_mask = ag->dcfg->desc_pktlen_mask;
        offset = ag->rx_buf_offset;
        ring_mask = BIT(ring->order) - 1;
        ring_size = BIT(ring->order);

        netif_dbg(ag, rx_status, ndev, "rx packets, limit=%d, curr=%u, dirty=%u\n",
                  limit, ring->curr, ring->dirty);

        INIT_LIST_HEAD(&rx_list);

        while (done < limit) {
                unsigned int i = ring->curr & ring_mask;
                struct ag71xx_desc *desc = ag71xx_ring_desc(ring, i);
                int pktlen;
                int err = 0;

                if (ag71xx_desc_empty(desc))
                        break;

                if ((ring->dirty + ring_size) == ring->curr) {
                        WARN_ONCE(1, "RX out of ring");
                        break;
                }

                ag71xx_wr(ag, AG71XX_REG_RX_STATUS, RX_STATUS_PR);

                pktlen = desc->ctrl & pktlen_mask;
                pktlen -= ETH_FCS_LEN;

                dma_unmap_single(&ag->pdev->dev, ring->buf[i].rx.dma_addr,
                                 ag->rx_buf_size, DMA_FROM_DEVICE);

                ndev->stats.rx_packets++;
                ndev->stats.rx_bytes += pktlen;

                skb = build_skb(ring->buf[i].rx.rx_buf, ag71xx_buffer_size(ag));
                if (!skb) {
                        skb_free_frag(ring->buf[i].rx.rx_buf);
                        goto next;
                }

                skb_reserve(skb, offset);
                skb_put(skb, pktlen);

                if (err) {
                        ndev->stats.rx_dropped++;
                        kfree_skb(skb);
                } else {
                        skb->dev = ndev;
                        skb->ip_summed = CHECKSUM_NONE;
                        list_add_tail(&skb->list, &rx_list);
                }

next:
                ring->buf[i].rx.rx_buf = NULL;
                done++;

                ring->curr++;
        }

        ag71xx_ring_rx_refill(ag);

        list_for_each_entry_safe(skb, next, &rx_list, list)
                skb->protocol = eth_type_trans(skb, ndev);
        netif_receive_skb_list(&rx_list);

        netif_dbg(ag, rx_status, ndev, "rx finish, curr=%u, dirty=%u, done=%d\n",
                  ring->curr, ring->dirty, done);

        return done;
}

static int ag71xx_poll(struct napi_struct *napi, int limit)
{
        struct ag71xx *ag = container_of(napi, struct ag71xx, napi);
        struct ag71xx_ring *rx_ring = &ag->rx_ring;
        int rx_ring_size = BIT(rx_ring->order);
        struct net_device *ndev = ag->ndev;
        int tx_done, rx_done;
        u32 status;

        tx_done = ag71xx_tx_packets(ag, false);

        netif_dbg(ag, rx_status, ndev, "processing RX ring\n");
        rx_done = ag71xx_rx_packets(ag, limit);

        if (!rx_ring->buf[rx_ring->dirty % rx_ring_size].rx.rx_buf)
                goto oom;

        status = ag71xx_rr(ag, AG71XX_REG_RX_STATUS);
        if (unlikely(status & RX_STATUS_OF)) {
                ag71xx_wr(ag, AG71XX_REG_RX_STATUS, RX_STATUS_OF);
                ndev->stats.rx_fifo_errors++;

                /* restart RX */
                ag71xx_wr(ag, AG71XX_REG_RX_CTRL, RX_CTRL_RXE);
        }

        if (rx_done < limit) {
                if (status & RX_STATUS_PR)
                        goto more;

                status = ag71xx_rr(ag, AG71XX_REG_TX_STATUS);
                if (status & TX_STATUS_PS)
                        goto more;

                netif_dbg(ag, rx_status, ndev, "disable polling mode, rx=%d, tx=%d,limit=%d\n",
                          rx_done, tx_done, limit);

                napi_complete(napi);

                /* enable interrupts */
                ag71xx_int_enable(ag, AG71XX_INT_POLL);
                return rx_done;
        }

more:
        netif_dbg(ag, rx_status, ndev, "stay in polling mode, rx=%d, tx=%d, limit=%d\n",
                  rx_done, tx_done, limit);
        return limit;

oom:
        netif_err(ag, rx_err, ndev, "out of memory\n");

        mod_timer(&ag->oom_timer, jiffies + AG71XX_OOM_REFILL);
        napi_complete(napi);
        return 0;
}

static irqreturn_t ag71xx_interrupt(int irq, void *dev_id)
{
        struct net_device *ndev = dev_id;
        struct ag71xx *ag;
        u32 status;

        ag = netdev_priv(ndev);
        status = ag71xx_rr(ag, AG71XX_REG_INT_STATUS);

        if (unlikely(!status))
                return IRQ_NONE;

        if (unlikely(status & AG71XX_INT_ERR)) {
                if (status & AG71XX_INT_TX_BE) {
                        ag71xx_wr(ag, AG71XX_REG_TX_STATUS, TX_STATUS_BE);
                        netif_err(ag, intr, ndev, "TX BUS error\n");
                }
                if (status & AG71XX_INT_RX_BE) {
                        ag71xx_wr(ag, AG71XX_REG_RX_STATUS, RX_STATUS_BE);
                        netif_err(ag, intr, ndev, "RX BUS error\n");
                }
        }

        if (likely(status & AG71XX_INT_POLL)) {
                ag71xx_int_disable(ag, AG71XX_INT_POLL);
                netif_dbg(ag, intr, ndev, "enable polling mode\n");
                napi_schedule(&ag->napi);
        }

        return IRQ_HANDLED;
}

static int ag71xx_change_mtu(struct net_device *ndev, int new_mtu)
{
        struct ag71xx *ag = netdev_priv(ndev);

        ndev->mtu = new_mtu;
        ag71xx_wr(ag, AG71XX_REG_MAC_MFL,
                  ag71xx_max_frame_len(ndev->mtu));

        return 0;
}

static const struct net_device_ops ag71xx_netdev_ops = {
        .ndo_open               = ag71xx_open,
        .ndo_stop               = ag71xx_stop,
        .ndo_start_xmit         = ag71xx_hard_start_xmit,
        .ndo_do_ioctl           = phy_do_ioctl,
        .ndo_tx_timeout         = ag71xx_tx_timeout,
        .ndo_change_mtu         = ag71xx_change_mtu,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};

static const u32 ar71xx_addr_ar7100[] = {
        0x19000000, 0x1a000000,
};

static int ag71xx_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        const struct ag71xx_dcfg *dcfg;
        struct net_device *ndev;
        struct resource *res;
        const void *mac_addr;
        int tx_size, err, i;
        struct ag71xx *ag;

        if (!np)
                return -ENODEV;

        ndev = devm_alloc_etherdev(&pdev->dev, sizeof(*ag));
        if (!ndev)
                return -ENOMEM;

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

        dcfg = of_device_get_match_data(&pdev->dev);
        if (!dcfg)
                return -EINVAL;

        ag = netdev_priv(ndev);
        ag->mac_idx = -1;
        for (i = 0; i < ARRAY_SIZE(ar71xx_addr_ar7100); i++) {
                if (ar71xx_addr_ar7100[i] == res->start)
                        ag->mac_idx = i;
        }

        if (ag->mac_idx < 0) {
                netif_err(ag, probe, ndev, "unknown mac idx\n");
                return -EINVAL;
        }

        ag->clk_eth = devm_clk_get(&pdev->dev, "eth");
        if (IS_ERR(ag->clk_eth)) {
                netif_err(ag, probe, ndev, "Failed to get eth clk.\n");
                return PTR_ERR(ag->clk_eth);
        }

        SET_NETDEV_DEV(ndev, &pdev->dev);

        ag->pdev = pdev;
        ag->ndev = ndev;
        ag->dcfg = dcfg;
        ag->msg_enable = netif_msg_init(-1, AG71XX_DEFAULT_MSG_ENABLE);
        memcpy(ag->fifodata, dcfg->fifodata, sizeof(ag->fifodata));

        ag->mac_reset = devm_reset_control_get(&pdev->dev, "mac");
        if (IS_ERR(ag->mac_reset)) {
                netif_err(ag, probe, ndev, "missing mac reset\n");
                err = PTR_ERR(ag->mac_reset);
                goto err_free;
        }

        ag->mac_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
        if (!ag->mac_base) {
                err = -ENOMEM;
                goto err_free;
        }

        ndev->irq = platform_get_irq(pdev, 0);
        err = devm_request_irq(&pdev->dev, ndev->irq, ag71xx_interrupt,
                               0x0, dev_name(&pdev->dev), ndev);
        if (err) {
                netif_err(ag, probe, ndev, "unable to request IRQ %d\n",
                          ndev->irq);
                goto err_free;
        }

        ndev->netdev_ops = &ag71xx_netdev_ops;

        INIT_DELAYED_WORK(&ag->restart_work, ag71xx_restart_work_func);
        timer_setup(&ag->oom_timer, ag71xx_oom_timer_handler, 0);

        tx_size = AG71XX_TX_RING_SIZE_DEFAULT;
        ag->rx_ring.order = ag71xx_ring_size_order(AG71XX_RX_RING_SIZE_DEFAULT);

        ndev->min_mtu = 68;
        ndev->max_mtu = dcfg->max_frame_len - ag71xx_max_frame_len(0);

        ag->rx_buf_offset = NET_SKB_PAD;
        if (!ag71xx_is(ag, AR7100) && !ag71xx_is(ag, AR9130))
                ag->rx_buf_offset += NET_IP_ALIGN;

        if (ag71xx_is(ag, AR7100)) {
                ag->tx_ring.desc_split = AG71XX_TX_RING_SPLIT;
                tx_size *= AG71XX_TX_RING_DS_PER_PKT;
        }
        ag->tx_ring.order = ag71xx_ring_size_order(tx_size);

        ag->stop_desc = dmam_alloc_coherent(&pdev->dev,
                                            sizeof(struct ag71xx_desc),
                                            &ag->stop_desc_dma, GFP_KERNEL);
        if (!ag->stop_desc) {
                err = -ENOMEM;
                goto err_free;
        }

        ag->stop_desc->data = 0;
        ag->stop_desc->ctrl = 0;
        ag->stop_desc->next = (u32)ag->stop_desc_dma;

        mac_addr = of_get_mac_address(np);
        if (!IS_ERR(mac_addr))
                memcpy(ndev->dev_addr, mac_addr, ETH_ALEN);
        if (IS_ERR(mac_addr) || !is_valid_ether_addr(ndev->dev_addr)) {
                netif_err(ag, probe, ndev, "invalid MAC address, using random address\n");
                eth_random_addr(ndev->dev_addr);
        }

        err = of_get_phy_mode(np, &ag->phy_if_mode);
        if (err) {
                netif_err(ag, probe, ndev, "missing phy-mode property in DT\n");
                goto err_free;
        }

        netif_napi_add(ndev, &ag->napi, ag71xx_poll, AG71XX_NAPI_WEIGHT);

        err = clk_prepare_enable(ag->clk_eth);
        if (err) {
                netif_err(ag, probe, ndev, "Failed to enable eth clk.\n");
                goto err_free;
        }

        ag71xx_wr(ag, AG71XX_REG_MAC_CFG1, 0);

        ag71xx_hw_init(ag);

        err = ag71xx_mdio_probe(ag);
        if (err)
                goto err_put_clk;

        platform_set_drvdata(pdev, ndev);

        err = ag71xx_phylink_setup(ag);
        if (err) {
                netif_err(ag, probe, ndev, "failed to setup phylink (%d)\n", err);
                goto err_mdio_remove;
        }

        err = register_netdev(ndev);
        if (err) {
                netif_err(ag, probe, ndev, "unable to register net device\n");
                platform_set_drvdata(pdev, NULL);
                goto err_mdio_remove;
        }

        netif_info(ag, probe, ndev, "Atheros AG71xx at 0x%08lx, irq %d, mode:%s\n",
                   (unsigned long)ag->mac_base, ndev->irq,
                   phy_modes(ag->phy_if_mode));

        return 0;

err_mdio_remove:
        ag71xx_mdio_remove(ag);
err_put_clk:
        clk_disable_unprepare(ag->clk_eth);
err_free:
        free_netdev(ndev);
        return err;
}

static int ag71xx_remove(struct platform_device *pdev)
{
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct ag71xx *ag;

        if (!ndev)
                return 0;

        ag = netdev_priv(ndev);
        unregister_netdev(ndev);
        ag71xx_mdio_remove(ag);
        clk_disable_unprepare(ag->clk_eth);
        platform_set_drvdata(pdev, NULL);

        return 0;
}

static const u32 ar71xx_fifo_ar7100[] = {
        0x0fff0000, 0x00001fff, 0x00780fff,
};

static const u32 ar71xx_fifo_ar9130[] = {
        0x0fff0000, 0x00001fff, 0x008001ff,
};

static const u32 ar71xx_fifo_ar9330[] = {
        0x0010ffff, 0x015500aa, 0x01f00140,
};

static const struct ag71xx_dcfg ag71xx_dcfg_ar7100 = {
        .type = AR7100,
        .fifodata = ar71xx_fifo_ar7100,
        .max_frame_len = 1540,
        .desc_pktlen_mask = SZ_4K - 1,
        .tx_hang_workaround = false,
};

static const struct ag71xx_dcfg ag71xx_dcfg_ar7240 = {
        .type = AR7240,
        .fifodata = ar71xx_fifo_ar7100,
        .max_frame_len = 1540,
        .desc_pktlen_mask = SZ_4K - 1,
        .tx_hang_workaround = true,
};

static const struct ag71xx_dcfg ag71xx_dcfg_ar9130 = {
        .type = AR9130,
        .fifodata = ar71xx_fifo_ar9130,
        .max_frame_len = 1540,
        .desc_pktlen_mask = SZ_4K - 1,
        .tx_hang_workaround = false,
};

static const struct ag71xx_dcfg ag71xx_dcfg_ar9330 = {
        .type = AR9330,
        .fifodata = ar71xx_fifo_ar9330,
        .max_frame_len = 1540,
        .desc_pktlen_mask = SZ_4K - 1,
        .tx_hang_workaround = true,
};

static const struct ag71xx_dcfg ag71xx_dcfg_ar9340 = {
        .type = AR9340,
        .fifodata = ar71xx_fifo_ar9330,
        .max_frame_len = SZ_16K - 1,
        .desc_pktlen_mask = SZ_16K - 1,
        .tx_hang_workaround = true,
};

static const struct ag71xx_dcfg ag71xx_dcfg_qca9530 = {
        .type = QCA9530,
        .fifodata = ar71xx_fifo_ar9330,
        .max_frame_len = SZ_16K - 1,
        .desc_pktlen_mask = SZ_16K - 1,
        .tx_hang_workaround = true,
};

static const struct ag71xx_dcfg ag71xx_dcfg_qca9550 = {
        .type = QCA9550,
        .fifodata = ar71xx_fifo_ar9330,
        .max_frame_len = 1540,
        .desc_pktlen_mask = SZ_16K - 1,
        .tx_hang_workaround = true,
};

static const struct of_device_id ag71xx_match[] = {
        { .compatible = "qca,ar7100-eth", .data = &ag71xx_dcfg_ar7100 },
        { .compatible = "qca,ar7240-eth", .data = &ag71xx_dcfg_ar7240 },
        { .compatible = "qca,ar7241-eth", .data = &ag71xx_dcfg_ar7240 },
        { .compatible = "qca,ar7242-eth", .data = &ag71xx_dcfg_ar7240 },
        { .compatible = "qca,ar9130-eth", .data = &ag71xx_dcfg_ar9130 },
        { .compatible = "qca,ar9330-eth", .data = &ag71xx_dcfg_ar9330 },
        { .compatible = "qca,ar9340-eth", .data = &ag71xx_dcfg_ar9340 },
        { .compatible = "qca,qca9530-eth", .data = &ag71xx_dcfg_qca9530 },
        { .compatible = "qca,qca9550-eth", .data = &ag71xx_dcfg_qca9550 },
        { .compatible = "qca,qca9560-eth", .data = &ag71xx_dcfg_qca9550 },
        {}
};

static struct platform_driver ag71xx_driver = {
        .probe          = ag71xx_probe,
        .remove         = ag71xx_remove,
        .driver = {
                .name   = "ag71xx",
                .of_match_table = ag71xx_match,
        }
};

module_platform_driver(ag71xx_driver);
MODULE_LICENSE("GPL v2");