/*
 * atari_nfeth.c - ARAnyM ethernet card driver for GNU/Linux
 *
 * Copyright (c) 2005 Milan Jurik, Petr Stehlik of ARAnyM dev team
 *
 * Based on ARAnyM driver for FreeMiNT written by Standa Opichal
 *
 * This software may be used and distributed according to the terms of
 * the GNU General Public License (GPL), incorporated herein by reference.
 */

#define DRV_VERSION     "0.3"
#define DRV_RELDATE     "10/12/2005"

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <asm/natfeat.h>
#include <asm/virtconvert.h>

enum {
        GET_VERSION = 0,/* no parameters, return NFAPI_VERSION in d0 */
        XIF_INTLEVEL,   /* no parameters, return Interrupt Level in d0 */
        XIF_IRQ,        /* acknowledge interrupt from host */
        XIF_START,      /* (ethX), called on 'ifup', start receiver thread */
        XIF_STOP,       /* (ethX), called on 'ifdown', stop the thread */
        XIF_READLENGTH, /* (ethX), return size of network data block to read */
        XIF_READBLOCK,  /* (ethX, buffer, size), read block of network data */
        XIF_WRITEBLOCK, /* (ethX, buffer, size), write block of network data */
        XIF_GET_MAC,    /* (ethX, buffer, size), return MAC HW addr in buffer */
        XIF_GET_IPHOST, /* (ethX, buffer, size), return IP address of host */
        XIF_GET_IPATARI,/* (ethX, buffer, size), return IP address of atari */
        XIF_GET_NETMASK /* (ethX, buffer, size), return IP netmask */
};

#define MAX_UNIT        8

/* These identify the driver base version and may not be removed. */
static const char version[] __maybe_unused =
        KERN_INFO KBUILD_MODNAME ".c:v" DRV_VERSION " " DRV_RELDATE
        " S.Opichal, M.Jurik, P.Stehlik\n"
        KERN_INFO " http://aranym.org/\n";

MODULE_AUTHOR("Milan Jurik");
MODULE_DESCRIPTION("Atari NFeth driver");
MODULE_LICENSE("GPL");


static long nfEtherID;
static int nfEtherIRQ;

struct nfeth_private {
        int ethX;
};

static struct net_device *nfeth_dev[MAX_UNIT];

static int nfeth_open(struct net_device *dev)
{
        struct nfeth_private *priv = netdev_priv(dev);
        int res;

        res = nf_call(nfEtherID + XIF_START, priv->ethX);
        netdev_dbg(dev, "%s: %d\n", __func__, res);

        /* Ready for data */
        netif_start_queue(dev);

        return 0;
}

static int nfeth_stop(struct net_device *dev)
{
        struct nfeth_private *priv = netdev_priv(dev);

        /* No more data */
        netif_stop_queue(dev);

        nf_call(nfEtherID + XIF_STOP, priv->ethX);

        return 0;
}

/*
 * Read a packet out of the adapter and pass it to the upper layers
 */
static inline void recv_packet(struct net_device *dev)
{
        struct nfeth_private *priv = netdev_priv(dev);
        unsigned short pktlen;
        struct sk_buff *skb;

        /* read packet length (excluding 32 bit crc) */
        pktlen = nf_call(nfEtherID + XIF_READLENGTH, priv->ethX);

        netdev_dbg(dev, "%s: %u\n", __func__, pktlen);

        if (!pktlen) {
                netdev_dbg(dev, "%s: pktlen == 0\n", __func__);
                dev->stats.rx_errors++;
                return;
        }

        skb = dev_alloc_skb(pktlen + 2);
        if (!skb) {
                netdev_dbg(dev, "%s: out of mem (buf_alloc failed)\n",
                           __func__);
                dev->stats.rx_dropped++;
                return;
        }

        skb->dev = dev;
        skb_reserve(skb, 2);            /* 16 Byte align  */
        skb_put(skb, pktlen);           /* make room */
        nf_call(nfEtherID + XIF_READBLOCK, priv->ethX, virt_to_phys(skb->data),
                pktlen);

        skb->protocol = eth_type_trans(skb, dev);
        netif_rx(skb);
        dev->stats.rx_packets++;
        dev->stats.rx_bytes += pktlen;

        /* and enqueue packet */
        return;
}

static irqreturn_t nfeth_interrupt(int irq, void *dev_id)
{
        int i, m, mask;

        mask = nf_call(nfEtherID + XIF_IRQ, 0);
        for (i = 0, m = 1; i < MAX_UNIT; m <<= 1, i++) {
                if (mask & m && nfeth_dev[i]) {
                        recv_packet(nfeth_dev[i]);
                        nf_call(nfEtherID + XIF_IRQ, m);
                }
        }
        return IRQ_HANDLED;
}

static int nfeth_xmit(struct sk_buff *skb, struct net_device *dev)
{
        unsigned int len;
        char *data, shortpkt[ETH_ZLEN];
        struct nfeth_private *priv = netdev_priv(dev);

        data = skb->data;
        len = skb->len;
        if (len < ETH_ZLEN) {
                memset(shortpkt, 0, ETH_ZLEN);
                memcpy(shortpkt, data, len);
                data = shortpkt;
                len = ETH_ZLEN;
        }

        netdev_dbg(dev, "%s: send %u bytes\n", __func__, len);
        nf_call(nfEtherID + XIF_WRITEBLOCK, priv->ethX, virt_to_phys(data),
                len);

        dev->stats.tx_packets++;
        dev->stats.tx_bytes += len;

        dev_kfree_skb(skb);
        return 0;
}

static void nfeth_tx_timeout(struct net_device *dev, unsigned int txqueue)
{
        dev->stats.tx_errors++;
        netif_wake_queue(dev);
}

static const struct net_device_ops nfeth_netdev_ops = {
        .ndo_open               = nfeth_open,
        .ndo_stop               = nfeth_stop,
        .ndo_start_xmit         = nfeth_xmit,
        .ndo_tx_timeout         = nfeth_tx_timeout,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_set_mac_address    = eth_mac_addr,
};

static struct net_device * __init nfeth_probe(int unit)
{
        struct net_device *dev;
        struct nfeth_private *priv;
        char mac[ETH_ALEN], host_ip[32], local_ip[32];
        int err;

        if (!nf_call(nfEtherID + XIF_GET_MAC, unit, virt_to_phys(mac),
                     ETH_ALEN))
                return NULL;

        dev = alloc_etherdev(sizeof(struct nfeth_private));
        if (!dev)
                return NULL;

        dev->irq = nfEtherIRQ;
        dev->netdev_ops = &nfeth_netdev_ops;

        eth_hw_addr_set(dev, mac);

        priv = netdev_priv(dev);
        priv->ethX = unit;

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

        nf_call(nfEtherID + XIF_GET_IPHOST, unit,
                virt_to_phys(host_ip), sizeof(host_ip));
        nf_call(nfEtherID + XIF_GET_IPATARI, unit,
                virt_to_phys(local_ip), sizeof(local_ip));

        netdev_info(dev, KBUILD_MODNAME " addr:%s (%s) HWaddr:%pM\n", host_ip,
                    local_ip, mac);

        return dev;
}

static int __init nfeth_init(void)
{
        long ver;
        int error, i;

        nfEtherID = nf_get_id("ETHERNET");
        if (!nfEtherID)
                return -ENODEV;

        ver = nf_call(nfEtherID + GET_VERSION);
        pr_info("API %lu\n", ver);

        nfEtherIRQ = nf_call(nfEtherID + XIF_INTLEVEL);
        error = request_irq(nfEtherIRQ, nfeth_interrupt, IRQF_SHARED,
                            "eth emu", nfeth_interrupt);
        if (error) {
                pr_err("request for irq %d failed %d", nfEtherIRQ, error);
                return error;
        }

        for (i = 0; i < MAX_UNIT; i++)
                nfeth_dev[i] = nfeth_probe(i);

        return 0;
}

static void __exit nfeth_cleanup(void)
{
        int i;

        for (i = 0; i < MAX_UNIT; i++) {
                if (nfeth_dev[i]) {
                        unregister_netdev(nfeth_dev[i]);
                        free_netdev(nfeth_dev[i]);
                }
        }
        free_irq(nfEtherIRQ, nfeth_interrupt);
}

module_init(nfeth_init);
module_exit(nfeth_cleanup);