// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * meth.c -- O2 Builtin 10/100 Ethernet driver
 *
 * Copyright (C) 2001-2003 Ilya Volynets
 */
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/interrupt.h>

#include <linux/in.h>
#include <linux/in6.h>
#include <linux/device.h> /* struct device, et al */
#include <linux/netdevice.h>   /* struct device, and other headers */
#include <linux/etherdevice.h> /* eth_type_trans */
#include <linux/ip.h>          /* struct iphdr */
#include <linux/tcp.h>         /* struct tcphdr */
#include <linux/skbuff.h>
#include <linux/mii.h>         /* MII definitions */
#include <linux/crc32.h>

#include <asm/ip32/mace.h>
#include <asm/ip32/ip32_ints.h>

#include <asm/io.h>

#include "meth.h"

#ifndef MFE_DEBUG
#define MFE_DEBUG 0
#endif

#if MFE_DEBUG>=1
#define DPRINTK(str,args...) printk(KERN_DEBUG "meth: %s: " str, __func__ , ## args)
#define MFE_RX_DEBUG 2
#else
#define DPRINTK(str,args...)
#define MFE_RX_DEBUG 0
#endif


static const char *meth_str="SGI O2 Fast Ethernet";

/* The maximum time waited (in jiffies) before assuming a Tx failed. (400ms) */
#define TX_TIMEOUT (400*HZ/1000)

static int timeout = TX_TIMEOUT;
module_param(timeout, int, 0);

/*
 * Maximum number of multicast addresses to filter (vs. Rx-all-multicast).
 * MACE Ethernet uses a 64 element hash table based on the Ethernet CRC.
 */
#define METH_MCF_LIMIT 32

/*
 * This structure is private to each device. It is used to pass
 * packets in and out, so there is place for a packet
 */
struct meth_private {
        struct platform_device *pdev;

        /* in-memory copy of MAC Control register */
        u64 mac_ctrl;

        /* in-memory copy of DMA Control register */
        unsigned long dma_ctrl;
        /* address of PHY, used by mdio_* functions, initialized in mdio_probe */
        unsigned long phy_addr;
        tx_packet *tx_ring;
        dma_addr_t tx_ring_dma;
        struct sk_buff *tx_skbs[TX_RING_ENTRIES];
        dma_addr_t tx_skb_dmas[TX_RING_ENTRIES];
        unsigned long tx_read, tx_write, tx_count;

        rx_packet *rx_ring[RX_RING_ENTRIES];
        dma_addr_t rx_ring_dmas[RX_RING_ENTRIES];
        struct sk_buff *rx_skbs[RX_RING_ENTRIES];
        unsigned long rx_write;

        /* Multicast filter. */
        u64 mcast_filter;

        spinlock_t meth_lock;
};

static void meth_tx_timeout(struct net_device *dev, unsigned int txqueue);
static irqreturn_t meth_interrupt(int irq, void *dev_id);

/* global, initialized in ip32-setup.c */
char o2meth_eaddr[8]={0,0,0,0,0,0,0,0};

static inline void load_eaddr(struct net_device *dev)
{
        int i;
        u64 macaddr;

        DPRINTK("Loading MAC Address: %pM\n", dev->dev_addr);
        macaddr = 0;
        for (i = 0; i < 6; i++)
                macaddr |= (u64)dev->dev_addr[i] << ((5 - i) * 8);

        mace->eth.mac_addr = macaddr;
}

/*
 * Waits for BUSY status of mdio bus to clear
 */
#define WAIT_FOR_PHY(___rval)                                   \
        while ((___rval = mace->eth.phy_data) & MDIO_BUSY) {    \
                udelay(25);                                     \
        }
/*read phy register, return value read */
static unsigned long mdio_read(struct meth_private *priv, unsigned long phyreg)
{
        unsigned long rval;
        WAIT_FOR_PHY(rval);
        mace->eth.phy_regs = (priv->phy_addr << 5) | (phyreg & 0x1f);
        udelay(25);
        mace->eth.phy_trans_go = 1;
        udelay(25);
        WAIT_FOR_PHY(rval);
        return rval & MDIO_DATA_MASK;
}

static int mdio_probe(struct meth_private *priv)
{
        int i;
        unsigned long p2, p3, flags;
        /* check if phy is detected already */
        if(priv->phy_addr>=0&&priv->phy_addr<32)
                return 0;
        spin_lock_irqsave(&priv->meth_lock, flags);
        for (i=0;i<32;++i){
                priv->phy_addr=i;
                p2=mdio_read(priv,2);
                p3=mdio_read(priv,3);
#if MFE_DEBUG>=2
                switch ((p2<<12)|(p3>>4)){
                case PHY_QS6612X:
                        DPRINTK("PHY is QS6612X\n");
                        break;
                case PHY_ICS1889:
                        DPRINTK("PHY is ICS1889\n");
                        break;
                case PHY_ICS1890:
                        DPRINTK("PHY is ICS1890\n");
                        break;
                case PHY_DP83840:
                        DPRINTK("PHY is DP83840\n");
                        break;
                }
#endif
                if(p2!=0xffff&&p2!=0x0000){
                        DPRINTK("PHY code: %x\n",(p2<<12)|(p3>>4));
                        break;
                }
        }
        spin_unlock_irqrestore(&priv->meth_lock, flags);
        if(priv->phy_addr<32) {
                return 0;
        }
        DPRINTK("Oopsie! PHY is not known!\n");
        priv->phy_addr=-1;
        return -ENODEV;
}

static void meth_check_link(struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);
        unsigned long mii_advertising = mdio_read(priv, 4);
        unsigned long mii_partner = mdio_read(priv, 5);
        unsigned long negotiated = mii_advertising & mii_partner;
        unsigned long duplex, speed;

        if (mii_partner == 0xffff)
                return;

        speed = (negotiated & 0x0380) ? METH_100MBIT : 0;
        duplex = ((negotiated & 0x0100) || (negotiated & 0x01C0) == 0x0040) ?
                 METH_PHY_FDX : 0;

        if ((priv->mac_ctrl & METH_PHY_FDX) ^ duplex) {
                DPRINTK("Setting %s-duplex\n", duplex ? "full" : "half");
                if (duplex)
                        priv->mac_ctrl |= METH_PHY_FDX;
                else
                        priv->mac_ctrl &= ~METH_PHY_FDX;
                mace->eth.mac_ctrl = priv->mac_ctrl;
        }

        if ((priv->mac_ctrl & METH_100MBIT) ^ speed) {
                DPRINTK("Setting %dMbs mode\n", speed ? 100 : 10);
                if (duplex)
                        priv->mac_ctrl |= METH_100MBIT;
                else
                        priv->mac_ctrl &= ~METH_100MBIT;
                mace->eth.mac_ctrl = priv->mac_ctrl;
        }
}


static int meth_init_tx_ring(struct meth_private *priv)
{
        /* Init TX ring */
        priv->tx_ring = dma_alloc_coherent(&priv->pdev->dev,
                        TX_RING_BUFFER_SIZE, &priv->tx_ring_dma, GFP_ATOMIC);
        if (!priv->tx_ring)
                return -ENOMEM;

        priv->tx_count = priv->tx_read = priv->tx_write = 0;
        mace->eth.tx_ring_base = priv->tx_ring_dma;
        /* Now init skb save area */
        memset(priv->tx_skbs, 0, sizeof(priv->tx_skbs));
        memset(priv->tx_skb_dmas, 0, sizeof(priv->tx_skb_dmas));
        return 0;
}

static int meth_init_rx_ring(struct meth_private *priv)
{
        int i;

        for (i = 0; i < RX_RING_ENTRIES; i++) {
                priv->rx_skbs[i] = alloc_skb(METH_RX_BUFF_SIZE, 0);
                /* 8byte status vector + 3quad padding + 2byte padding,
                 * to put data on 64bit aligned boundary */
                skb_reserve(priv->rx_skbs[i],METH_RX_HEAD);
                priv->rx_ring[i]=(rx_packet*)(priv->rx_skbs[i]->head);
                /* I'll need to re-sync it after each RX */
                priv->rx_ring_dmas[i] =
                        dma_map_single(&priv->pdev->dev, priv->rx_ring[i],
                                       METH_RX_BUFF_SIZE, DMA_FROM_DEVICE);
                mace->eth.rx_fifo = priv->rx_ring_dmas[i];
        }
        priv->rx_write = 0;
        return 0;
}
static void meth_free_tx_ring(struct meth_private *priv)
{
        int i;

        /* Remove any pending skb */
        for (i = 0; i < TX_RING_ENTRIES; i++) {
                dev_kfree_skb(priv->tx_skbs[i]);
                priv->tx_skbs[i] = NULL;
        }
        dma_free_coherent(&priv->pdev->dev, TX_RING_BUFFER_SIZE, priv->tx_ring,
                          priv->tx_ring_dma);
}

/* Presumes RX DMA engine is stopped, and RX fifo ring is reset */
static void meth_free_rx_ring(struct meth_private *priv)
{
        int i;

        for (i = 0; i < RX_RING_ENTRIES; i++) {
                dma_unmap_single(&priv->pdev->dev, priv->rx_ring_dmas[i],
                                 METH_RX_BUFF_SIZE, DMA_FROM_DEVICE);
                priv->rx_ring[i] = 0;
                priv->rx_ring_dmas[i] = 0;
                kfree_skb(priv->rx_skbs[i]);
        }
}

int meth_reset(struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);

        /* Reset card */
        mace->eth.mac_ctrl = SGI_MAC_RESET;
        udelay(1);
        mace->eth.mac_ctrl = 0;
        udelay(25);

        /* Load ethernet address */
        load_eaddr(dev);
        /* Should load some "errata", but later */

        /* Check for device */
        if (mdio_probe(priv) < 0) {
                DPRINTK("Unable to find PHY\n");
                return -ENODEV;
        }

        /* Initial mode: 10 | Half-duplex | Accept normal packets */
        priv->mac_ctrl = METH_ACCEPT_MCAST | METH_DEFAULT_IPG;
        if (dev->flags & IFF_PROMISC)
                priv->mac_ctrl |= METH_PROMISC;
        mace->eth.mac_ctrl = priv->mac_ctrl;

        /* Autonegotiate speed and duplex mode */
        meth_check_link(dev);

        /* Now set dma control, but don't enable DMA, yet */
        priv->dma_ctrl = (4 << METH_RX_OFFSET_SHIFT) |
                         (RX_RING_ENTRIES << METH_RX_DEPTH_SHIFT);
        mace->eth.dma_ctrl = priv->dma_ctrl;

        return 0;
}

/*============End Helper Routines=====================*/

/*
 * Open and close
 */
static int meth_open(struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);
        int ret;

        priv->phy_addr = -1;    /* No PHY is known yet... */

        /* Initialize the hardware */
        ret = meth_reset(dev);
        if (ret < 0)
                return ret;

        /* Allocate the ring buffers */
        ret = meth_init_tx_ring(priv);
        if (ret < 0)
                return ret;
        ret = meth_init_rx_ring(priv);
        if (ret < 0)
                goto out_free_tx_ring;

        ret = request_irq(dev->irq, meth_interrupt, 0, meth_str, dev);
        if (ret) {
                printk(KERN_ERR "%s: Can't get irq %d\n", dev->name, dev->irq);
                goto out_free_rx_ring;
        }

        /* Start DMA */
        priv->dma_ctrl |= METH_DMA_TX_EN | /*METH_DMA_TX_INT_EN |*/
                          METH_DMA_RX_EN | METH_DMA_RX_INT_EN;
        mace->eth.dma_ctrl = priv->dma_ctrl;

        DPRINTK("About to start queue\n");
        netif_start_queue(dev);

        return 0;

out_free_rx_ring:
        meth_free_rx_ring(priv);
out_free_tx_ring:
        meth_free_tx_ring(priv);

        return ret;
}

static int meth_release(struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);

        DPRINTK("Stopping queue\n");
        netif_stop_queue(dev); /* can't transmit any more */
        /* shut down DMA */
        priv->dma_ctrl &= ~(METH_DMA_TX_EN | METH_DMA_TX_INT_EN |
                            METH_DMA_RX_EN | METH_DMA_RX_INT_EN);
        mace->eth.dma_ctrl = priv->dma_ctrl;
        free_irq(dev->irq, dev);
        meth_free_tx_ring(priv);
        meth_free_rx_ring(priv);

        return 0;
}

/*
 * Receive a packet: retrieve, encapsulate and pass over to upper levels
 */
static void meth_rx(struct net_device* dev, unsigned long int_status)
{
        struct sk_buff *skb;
        unsigned long status, flags;
        struct meth_private *priv = netdev_priv(dev);
        unsigned long fifo_rptr = (int_status & METH_INT_RX_RPTR_MASK) >> 8;

        spin_lock_irqsave(&priv->meth_lock, flags);
        priv->dma_ctrl &= ~METH_DMA_RX_INT_EN;
        mace->eth.dma_ctrl = priv->dma_ctrl;
        spin_unlock_irqrestore(&priv->meth_lock, flags);

        if (int_status & METH_INT_RX_UNDERFLOW) {
                fifo_rptr = (fifo_rptr - 1) & 0x0f;
        }
        while (priv->rx_write != fifo_rptr) {
                dma_unmap_single(&priv->pdev->dev,
                                 priv->rx_ring_dmas[priv->rx_write],
                                 METH_RX_BUFF_SIZE, DMA_FROM_DEVICE);
                status = priv->rx_ring[priv->rx_write]->status.raw;
#if MFE_DEBUG
                if (!(status & METH_RX_ST_VALID)) {
                        DPRINTK("Not received? status=%016lx\n",status);
                }
#endif
                if ((!(status & METH_RX_STATUS_ERRORS)) && (status & METH_RX_ST_VALID)) {
                        int len = (status & 0xffff) - 4; /* omit CRC */
                        /* length sanity check */
                        if (len < 60 || len > 1518) {
                                printk(KERN_DEBUG "%s: bogus packet size: %ld, status=%#2Lx.\n",
                                       dev->name, priv->rx_write,
                                       priv->rx_ring[priv->rx_write]->status.raw);
                                dev->stats.rx_errors++;
                                dev->stats.rx_length_errors++;
                                skb = priv->rx_skbs[priv->rx_write];
                        } else {
                                skb = alloc_skb(METH_RX_BUFF_SIZE, GFP_ATOMIC);
                                if (!skb) {
                                        /* Ouch! No memory! Drop packet on the floor */
                                        DPRINTK("No mem: dropping packet\n");
                                        dev->stats.rx_dropped++;
                                        skb = priv->rx_skbs[priv->rx_write];
                                } else {
                                        struct sk_buff *skb_c = priv->rx_skbs[priv->rx_write];
                                        /* 8byte status vector + 3quad padding + 2byte padding,
                                         * to put data on 64bit aligned boundary */
                                        skb_reserve(skb, METH_RX_HEAD);
                                        /* Write metadata, and then pass to the receive level */
                                        skb_put(skb_c, len);
                                        priv->rx_skbs[priv->rx_write] = skb;
                                        skb_c->protocol = eth_type_trans(skb_c, dev);
                                        dev->stats.rx_packets++;
                                        dev->stats.rx_bytes += len;
                                        netif_rx(skb_c);
                                }
                        }
                } else {
                        dev->stats.rx_errors++;
                        skb=priv->rx_skbs[priv->rx_write];
#if MFE_DEBUG>0
                        printk(KERN_WARNING "meth: RX error: status=0x%016lx\n",status);
                        if(status&METH_RX_ST_RCV_CODE_VIOLATION)
                                printk(KERN_WARNING "Receive Code Violation\n");
                        if(status&METH_RX_ST_CRC_ERR)
                                printk(KERN_WARNING "CRC error\n");
                        if(status&METH_RX_ST_INV_PREAMBLE_CTX)
                                printk(KERN_WARNING "Invalid Preamble Context\n");
                        if(status&METH_RX_ST_LONG_EVT_SEEN)
                                printk(KERN_WARNING "Long Event Seen...\n");
                        if(status&METH_RX_ST_BAD_PACKET)
                                printk(KERN_WARNING "Bad Packet\n");
                        if(status&METH_RX_ST_CARRIER_EVT_SEEN)
                                printk(KERN_WARNING "Carrier Event Seen\n");
#endif
                }
                priv->rx_ring[priv->rx_write] = (rx_packet*)skb->head;
                priv->rx_ring[priv->rx_write]->status.raw = 0;
                priv->rx_ring_dmas[priv->rx_write] =
                        dma_map_single(&priv->pdev->dev,
                                       priv->rx_ring[priv->rx_write],
                                       METH_RX_BUFF_SIZE, DMA_FROM_DEVICE);
                mace->eth.rx_fifo = priv->rx_ring_dmas[priv->rx_write];
                ADVANCE_RX_PTR(priv->rx_write);
        }
        spin_lock_irqsave(&priv->meth_lock, flags);
        /* In case there was underflow, and Rx DMA was disabled */
        priv->dma_ctrl |= METH_DMA_RX_INT_EN | METH_DMA_RX_EN;
        mace->eth.dma_ctrl = priv->dma_ctrl;
        mace->eth.int_stat = METH_INT_RX_THRESHOLD;
        spin_unlock_irqrestore(&priv->meth_lock, flags);
}

static int meth_tx_full(struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);

        return priv->tx_count >= TX_RING_ENTRIES - 1;
}

static void meth_tx_cleanup(struct net_device* dev, unsigned long int_status)
{
        struct meth_private *priv = netdev_priv(dev);
        unsigned long status, flags;
        struct sk_buff *skb;
        unsigned long rptr = (int_status&TX_INFO_RPTR) >> 16;

        spin_lock_irqsave(&priv->meth_lock, flags);

        /* Stop DMA notification */
        priv->dma_ctrl &= ~(METH_DMA_TX_INT_EN);
        mace->eth.dma_ctrl = priv->dma_ctrl;

        while (priv->tx_read != rptr) {
                skb = priv->tx_skbs[priv->tx_read];
                status = priv->tx_ring[priv->tx_read].header.raw;
#if MFE_DEBUG>=1
                if (priv->tx_read == priv->tx_write)
                        DPRINTK("Auchi! tx_read=%d,tx_write=%d,rptr=%d?\n", priv->tx_read, priv->tx_write,rptr);
#endif
                if (status & METH_TX_ST_DONE) {
                        if (status & METH_TX_ST_SUCCESS){
                                dev->stats.tx_packets++;
                                dev->stats.tx_bytes += skb->len;
                        } else {
                                dev->stats.tx_errors++;
#if MFE_DEBUG>=1
                                DPRINTK("TX error: status=%016lx <",status);
                                if(status & METH_TX_ST_SUCCESS)
                                        printk(" SUCCESS");
                                if(status & METH_TX_ST_TOOLONG)
                                        printk(" TOOLONG");
                                if(status & METH_TX_ST_UNDERRUN)
                                        printk(" UNDERRUN");
                                if(status & METH_TX_ST_EXCCOLL)
                                        printk(" EXCCOLL");
                                if(status & METH_TX_ST_DEFER)
                                        printk(" DEFER");
                                if(status & METH_TX_ST_LATECOLL)
                                        printk(" LATECOLL");
                                printk(" >\n");
#endif
                        }
                } else {
                        DPRINTK("RPTR points us here, but packet not done?\n");
                        break;
                }
                dev_consume_skb_irq(skb);
                priv->tx_skbs[priv->tx_read] = NULL;
                priv->tx_ring[priv->tx_read].header.raw = 0;
                priv->tx_read = (priv->tx_read+1)&(TX_RING_ENTRIES-1);
                priv->tx_count--;
        }

        /* wake up queue if it was stopped */
        if (netif_queue_stopped(dev) && !meth_tx_full(dev)) {
                netif_wake_queue(dev);
        }

        mace->eth.int_stat = METH_INT_TX_EMPTY | METH_INT_TX_PKT;
        spin_unlock_irqrestore(&priv->meth_lock, flags);
}

static void meth_error(struct net_device* dev, unsigned status)
{
        struct meth_private *priv = netdev_priv(dev);
        unsigned long flags;

        printk(KERN_WARNING "meth: error status: 0x%08x\n",status);
        /* check for errors too... */
        if (status & (METH_INT_TX_LINK_FAIL))
                printk(KERN_WARNING "meth: link failure\n");
        /* Should I do full reset in this case? */
        if (status & (METH_INT_MEM_ERROR))
                printk(KERN_WARNING "meth: memory error\n");
        if (status & (METH_INT_TX_ABORT))
                printk(KERN_WARNING "meth: aborted\n");
        if (status & (METH_INT_RX_OVERFLOW))
                printk(KERN_WARNING "meth: Rx overflow\n");
        if (status & (METH_INT_RX_UNDERFLOW)) {
                printk(KERN_WARNING "meth: Rx underflow\n");
                spin_lock_irqsave(&priv->meth_lock, flags);
                mace->eth.int_stat = METH_INT_RX_UNDERFLOW;
                /* more underflow interrupts will be delivered,
                 * effectively throwing us into an infinite loop.
                 *  Thus I stop processing Rx in this case. */
                priv->dma_ctrl &= ~METH_DMA_RX_EN;
                mace->eth.dma_ctrl = priv->dma_ctrl;
                DPRINTK("Disabled meth Rx DMA temporarily\n");
                spin_unlock_irqrestore(&priv->meth_lock, flags);
        }
        mace->eth.int_stat = METH_INT_ERROR;
}

/*
 * The typical interrupt entry point
 */
static irqreturn_t meth_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = (struct net_device *)dev_id;
        struct meth_private *priv = netdev_priv(dev);
        unsigned long status;

        status = mace->eth.int_stat;
        while (status & 0xff) {
                /* First handle errors - if we get Rx underflow,
                 * Rx DMA will be disabled, and Rx handler will reenable
                 * it. I don't think it's possible to get Rx underflow,
                 * without getting Rx interrupt */
                if (status & METH_INT_ERROR) {
                        meth_error(dev, status);
                }
                if (status & (METH_INT_TX_EMPTY | METH_INT_TX_PKT)) {
                        /* a transmission is over: free the skb */
                        meth_tx_cleanup(dev, status);
                }
                if (status & METH_INT_RX_THRESHOLD) {
                        if (!(priv->dma_ctrl & METH_DMA_RX_INT_EN))
                                break;
                        /* send it to meth_rx for handling */
                        meth_rx(dev, status);
                }
                status = mace->eth.int_stat;
        }

        return IRQ_HANDLED;
}

/*
 * Transmits packets that fit into TX descriptor (are <=120B)
 */
static void meth_tx_short_prepare(struct meth_private *priv,
                                  struct sk_buff *skb)
{
        tx_packet *desc = &priv->tx_ring[priv->tx_write];
        int len = (skb->len < ETH_ZLEN) ? ETH_ZLEN : skb->len;

        desc->header.raw = METH_TX_CMD_INT_EN | (len-1) | ((128-len) << 16);
        /* maybe I should set whole thing to 0 first... */
        skb_copy_from_linear_data(skb, desc->data.dt + (120 - len), skb->len);
        if (skb->len < len)
                memset(desc->data.dt + 120 - len + skb->len, 0, len-skb->len);
}
#define TX_CATBUF1 BIT(25)
static void meth_tx_1page_prepare(struct meth_private *priv,
                                  struct sk_buff *skb)
{
        tx_packet *desc = &priv->tx_ring[priv->tx_write];
        void *buffer_data = (void *)(((unsigned long)skb->data + 7) & ~7);
        int unaligned_len = (int)((unsigned long)buffer_data - (unsigned long)skb->data);
        int buffer_len = skb->len - unaligned_len;
        dma_addr_t catbuf;

        desc->header.raw = METH_TX_CMD_INT_EN | TX_CATBUF1 | (skb->len - 1);

        /* unaligned part */
        if (unaligned_len) {
                skb_copy_from_linear_data(skb, desc->data.dt + (120 - unaligned_len),
                              unaligned_len);
                desc->header.raw |= (128 - unaligned_len) << 16;
        }

        /* first page */
        catbuf = dma_map_single(&priv->pdev->dev, buffer_data, buffer_len,
                                DMA_TO_DEVICE);
        desc->data.cat_buf[0].form.start_addr = catbuf >> 3;
        desc->data.cat_buf[0].form.len = buffer_len - 1;
}
#define TX_CATBUF2 BIT(26)
static void meth_tx_2page_prepare(struct meth_private *priv,
                                  struct sk_buff *skb)
{
        tx_packet *desc = &priv->tx_ring[priv->tx_write];
        void *buffer1_data = (void *)(((unsigned long)skb->data + 7) & ~7);
        void *buffer2_data = (void *)PAGE_ALIGN((unsigned long)skb->data);
        int unaligned_len = (int)((unsigned long)buffer1_data - (unsigned long)skb->data);
        int buffer1_len = (int)((unsigned long)buffer2_data - (unsigned long)buffer1_data);
        int buffer2_len = skb->len - buffer1_len - unaligned_len;
        dma_addr_t catbuf1, catbuf2;

        desc->header.raw = METH_TX_CMD_INT_EN | TX_CATBUF1 | TX_CATBUF2| (skb->len - 1);
        /* unaligned part */
        if (unaligned_len){
                skb_copy_from_linear_data(skb, desc->data.dt + (120 - unaligned_len),
                              unaligned_len);
                desc->header.raw |= (128 - unaligned_len) << 16;
        }

        /* first page */
        catbuf1 = dma_map_single(&priv->pdev->dev, buffer1_data, buffer1_len,
                                 DMA_TO_DEVICE);
        desc->data.cat_buf[0].form.start_addr = catbuf1 >> 3;
        desc->data.cat_buf[0].form.len = buffer1_len - 1;
        /* second page */
        catbuf2 = dma_map_single(&priv->pdev->dev, buffer2_data, buffer2_len,
                                 DMA_TO_DEVICE);
        desc->data.cat_buf[1].form.start_addr = catbuf2 >> 3;
        desc->data.cat_buf[1].form.len = buffer2_len - 1;
}

static void meth_add_to_tx_ring(struct meth_private *priv, struct sk_buff *skb)
{
        /* Remember the skb, so we can free it at interrupt time */
        priv->tx_skbs[priv->tx_write] = skb;
        if (skb->len <= 120) {
                /* Whole packet fits into descriptor */
                meth_tx_short_prepare(priv, skb);
        } else if (PAGE_ALIGN((unsigned long)skb->data) !=
                   PAGE_ALIGN((unsigned long)skb->data + skb->len - 1)) {
                /* Packet crosses page boundary */
                meth_tx_2page_prepare(priv, skb);
        } else {
                /* Packet is in one page */
                meth_tx_1page_prepare(priv, skb);
        }
        priv->tx_write = (priv->tx_write + 1) & (TX_RING_ENTRIES - 1);
        mace->eth.tx_info = priv->tx_write;
        priv->tx_count++;
}

/*
 * Transmit a packet (called by the kernel)
 */
static netdev_tx_t meth_tx(struct sk_buff *skb, struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);
        unsigned long flags;

        spin_lock_irqsave(&priv->meth_lock, flags);
        /* Stop DMA notification */
        priv->dma_ctrl &= ~(METH_DMA_TX_INT_EN);
        mace->eth.dma_ctrl = priv->dma_ctrl;

        meth_add_to_tx_ring(priv, skb);
        netif_trans_update(dev); /* save the timestamp */

        /* If TX ring is full, tell the upper layer to stop sending packets */
        if (meth_tx_full(dev)) {
                printk(KERN_DEBUG "TX full: stopping\n");
                netif_stop_queue(dev);
        }

        /* Restart DMA notification */
        priv->dma_ctrl |= METH_DMA_TX_INT_EN;
        mace->eth.dma_ctrl = priv->dma_ctrl;

        spin_unlock_irqrestore(&priv->meth_lock, flags);

        return NETDEV_TX_OK;
}

/*
 * Deal with a transmit timeout.
 */
static void meth_tx_timeout(struct net_device *dev, unsigned int txqueue)
{
        struct meth_private *priv = netdev_priv(dev);
        unsigned long flags;

        printk(KERN_WARNING "%s: transmit timed out\n", dev->name);

        /* Protect against concurrent rx interrupts */
        spin_lock_irqsave(&priv->meth_lock,flags);

        /* Try to reset the interface. */
        meth_reset(dev);

        dev->stats.tx_errors++;

        /* Clear all rings */
        meth_free_tx_ring(priv);
        meth_free_rx_ring(priv);
        meth_init_tx_ring(priv);
        meth_init_rx_ring(priv);

        /* Restart dma */
        priv->dma_ctrl |= METH_DMA_TX_EN | METH_DMA_RX_EN | METH_DMA_RX_INT_EN;
        mace->eth.dma_ctrl = priv->dma_ctrl;

        /* Enable interrupt */
        spin_unlock_irqrestore(&priv->meth_lock, flags);

        netif_trans_update(dev); /* prevent tx timeout */
        netif_wake_queue(dev);
}

/*
 * Ioctl commands
 */
static int meth_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
{
        /* XXX Not yet implemented */
        switch(cmd) {
        case SIOCGMIIPHY:
        case SIOCGMIIREG:
        case SIOCSMIIREG:
        default:
                return -EOPNOTSUPP;
        }
}

static void meth_set_rx_mode(struct net_device *dev)
{
        struct meth_private *priv = netdev_priv(dev);
        unsigned long flags;

        netif_stop_queue(dev);
        spin_lock_irqsave(&priv->meth_lock, flags);
        priv->mac_ctrl &= ~METH_PROMISC;

        if (dev->flags & IFF_PROMISC) {
                priv->mac_ctrl |= METH_PROMISC;
                priv->mcast_filter = 0xffffffffffffffffUL;
        } else if ((netdev_mc_count(dev) > METH_MCF_LIMIT) ||
                   (dev->flags & IFF_ALLMULTI)) {
                priv->mac_ctrl |= METH_ACCEPT_AMCAST;
                priv->mcast_filter = 0xffffffffffffffffUL;
        } else {
                struct netdev_hw_addr *ha;
                priv->mac_ctrl |= METH_ACCEPT_MCAST;

                netdev_for_each_mc_addr(ha, dev)
                        set_bit((ether_crc(ETH_ALEN, ha->addr) >> 26),
                                (volatile unsigned long *)&priv->mcast_filter);
        }

        /* Write the changes to the chip registers. */
        mace->eth.mac_ctrl = priv->mac_ctrl;
        mace->eth.mcast_filter = priv->mcast_filter;

        /* Done! */
        spin_unlock_irqrestore(&priv->meth_lock, flags);
        netif_wake_queue(dev);
}

static const struct net_device_ops meth_netdev_ops = {
        .ndo_open               = meth_open,
        .ndo_stop               = meth_release,
        .ndo_start_xmit         = meth_tx,
        .ndo_eth_ioctl          = meth_ioctl,
        .ndo_tx_timeout         = meth_tx_timeout,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_set_rx_mode        = meth_set_rx_mode,
};

/*
 * The init function.
 */
static int meth_probe(struct platform_device *pdev)
{
        struct net_device *dev;
        struct meth_private *priv;
        int err;

        dev = alloc_etherdev(sizeof(struct meth_private));
        if (!dev)
                return -ENOMEM;

        dev->netdev_ops         = &meth_netdev_ops;
        dev->watchdog_timeo     = timeout;
        dev->irq                = MACE_ETHERNET_IRQ;
        dev->base_addr          = (unsigned long)&mace->eth;
        eth_hw_addr_set(dev, o2meth_eaddr);

        priv = netdev_priv(dev);
        priv->pdev = pdev;
        spin_lock_init(&priv->meth_lock);
        SET_NETDEV_DEV(dev, &pdev->dev);

        err = register_netdev(dev);
        if (err) {
                free_netdev(dev);
                return err;
        }

        printk(KERN_INFO "%s: SGI MACE Ethernet rev. %d\n",
               dev->name, (unsigned int)(mace->eth.mac_ctrl >> 29));
        return 0;
}

static void meth_remove(struct platform_device *pdev)
{
        struct net_device *dev = platform_get_drvdata(pdev);

        unregister_netdev(dev);
        free_netdev(dev);
}

static struct platform_driver meth_driver = {
        .probe  = meth_probe,
        .remove = meth_remove,
        .driver = {
                .name   = "meth",
        }
};

module_platform_driver(meth_driver);

MODULE_AUTHOR("Ilya Volynets <ilya@theIlya.com>");
MODULE_DESCRIPTION("SGI O2 Builtin Fast Ethernet driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:meth");