/*
 * Davicom DM96xx USB 10/100Mbps ethernet devices
 *
 * Peter Korsgaard <jacmet@sunsite.dk>
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2.  This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

//#define DEBUG

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/stddef.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/crc32.h>
#include <linux/usb/usbnet.h>
#include <linux/slab.h>

/* datasheet:
 http://ptm2.cc.utu.fi/ftp/network/cards/DM9601/From_NET/DM9601-DS-P01-930914.pdf
*/

/* control requests */
#define DM_READ_REGS    0x00
#define DM_WRITE_REGS   0x01
#define DM_READ_MEMS    0x02
#define DM_WRITE_REG    0x03
#define DM_WRITE_MEMS   0x05
#define DM_WRITE_MEM    0x07

/* registers */
#define DM_NET_CTRL     0x00
#define DM_RX_CTRL      0x05
#define DM_SHARED_CTRL  0x0b
#define DM_SHARED_ADDR  0x0c
#define DM_SHARED_DATA  0x0d    /* low + high */
#define DM_PHY_ADDR     0x10    /* 6 bytes */
#define DM_MCAST_ADDR   0x16    /* 8 bytes */
#define DM_GPR_CTRL     0x1e
#define DM_GPR_DATA     0x1f
#define DM_CHIP_ID      0x2c
#define DM_MODE_CTRL    0x91    /* only on dm9620 */

/* chip id values */
#define ID_DM9601       0
#define ID_DM9620       1

#define DM_MAX_MCAST    64
#define DM_MCAST_SIZE   8
#define DM_EEPROM_LEN   256
#define DM_TX_OVERHEAD  2       /* 2 byte header */
#define DM_RX_OVERHEAD  7       /* 3 byte header + 4 byte crc tail */
#define DM_TIMEOUT      1000

static int dm_read(struct usbnet *dev, u8 reg, u16 length, void *data)
{
        int err;
        err = usbnet_read_cmd(dev, DM_READ_REGS,
                               USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                               0, reg, data, length);
        if(err != length && err >= 0)
                err = -EINVAL;
        return err;
}

static int dm_read_reg(struct usbnet *dev, u8 reg, u8 *value)
{
        return dm_read(dev, reg, 1, value);
}

static int dm_write(struct usbnet *dev, u8 reg, u16 length, void *data)
{
        int err;
        err = usbnet_write_cmd(dev, DM_WRITE_REGS,
                                USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                0, reg, data, length);

        if (err >= 0 && err < length)
                err = -EINVAL;
        return err;
}

static int dm_write_reg(struct usbnet *dev, u8 reg, u8 value)
{
        return usbnet_write_cmd(dev, DM_WRITE_REG,
                                USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                                value, reg, NULL, 0);
}

static void dm_write_async(struct usbnet *dev, u8 reg, u16 length,
                           const void *data)
{
        usbnet_write_cmd_async(dev, DM_WRITE_REGS,
                               USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                               0, reg, data, length);
}

static void dm_write_reg_async(struct usbnet *dev, u8 reg, u8 value)
{
        usbnet_write_cmd_async(dev, DM_WRITE_REG,
                               USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                               value, reg, NULL, 0);
}

static int dm_read_shared_word(struct usbnet *dev, int phy, u8 reg, __le16 *value)
{
        int ret, i;

        mutex_lock(&dev->phy_mutex);

        dm_write_reg(dev, DM_SHARED_ADDR, phy ? (reg | 0x40) : reg);
        dm_write_reg(dev, DM_SHARED_CTRL, phy ? 0xc : 0x4);

        for (i = 0; i < DM_TIMEOUT; i++) {
                u8 tmp = 0;

                udelay(1);
                ret = dm_read_reg(dev, DM_SHARED_CTRL, &tmp);
                if (ret < 0)
                        goto out;

                /* ready */
                if ((tmp & 1) == 0)
                        break;
        }

        if (i == DM_TIMEOUT) {
                netdev_err(dev->net, "%s read timed out!\n", phy ? "phy" : "eeprom");
                ret = -EIO;
                goto out;
        }

        dm_write_reg(dev, DM_SHARED_CTRL, 0x0);
        ret = dm_read(dev, DM_SHARED_DATA, 2, value);

        netdev_dbg(dev->net, "read shared %d 0x%02x returned 0x%04x, %d\n",
                   phy, reg, *value, ret);

 out:
        mutex_unlock(&dev->phy_mutex);
        return ret;
}

static int dm_write_shared_word(struct usbnet *dev, int phy, u8 reg, __le16 value)
{
        int ret, i;

        mutex_lock(&dev->phy_mutex);

        ret = dm_write(dev, DM_SHARED_DATA, 2, &value);
        if (ret < 0)
                goto out;

        dm_write_reg(dev, DM_SHARED_ADDR, phy ? (reg | 0x40) : reg);
        dm_write_reg(dev, DM_SHARED_CTRL, phy ? 0x1a : 0x12);

        for (i = 0; i < DM_TIMEOUT; i++) {
                u8 tmp = 0;

                udelay(1);
                ret = dm_read_reg(dev, DM_SHARED_CTRL, &tmp);
                if (ret < 0)
                        goto out;

                /* ready */
                if ((tmp & 1) == 0)
                        break;
        }

        if (i == DM_TIMEOUT) {
                netdev_err(dev->net, "%s write timed out!\n", phy ? "phy" : "eeprom");
                ret = -EIO;
                goto out;
        }

        dm_write_reg(dev, DM_SHARED_CTRL, 0x0);

out:
        mutex_unlock(&dev->phy_mutex);
        return ret;
}

static int dm_read_eeprom_word(struct usbnet *dev, u8 offset, void *value)
{
        return dm_read_shared_word(dev, 0, offset, value);
}



static int dm9601_get_eeprom_len(struct net_device *dev)
{
        return DM_EEPROM_LEN;
}

static int dm9601_get_eeprom(struct net_device *net,
                             struct ethtool_eeprom *eeprom, u8 * data)
{
        struct usbnet *dev = netdev_priv(net);
        __le16 *ebuf = (__le16 *) data;
        int i;

        /* access is 16bit */
        if ((eeprom->offset % 2) || (eeprom->len % 2))
                return -EINVAL;

        for (i = 0; i < eeprom->len / 2; i++) {
                if (dm_read_eeprom_word(dev, eeprom->offset / 2 + i,
                                        &ebuf[i]) < 0)
                        return -EINVAL;
        }
        return 0;
}

static int dm9601_mdio_read(struct net_device *netdev, int phy_id, int loc)
{
        struct usbnet *dev = netdev_priv(netdev);

        __le16 res;
        int err;

        if (phy_id) {
                netdev_dbg(dev->net, "Only internal phy supported\n");
                return 0;
        }

        err = dm_read_shared_word(dev, 1, loc, &res);
        if (err < 0) {
                netdev_err(dev->net, "MDIO read error: %d\n", err);
                return 0;
        }

        netdev_dbg(dev->net,
                   "dm9601_mdio_read() phy_id=0x%02x, loc=0x%02x, returns=0x%04x\n",
                   phy_id, loc, le16_to_cpu(res));

        return le16_to_cpu(res);
}

static void dm9601_mdio_write(struct net_device *netdev, int phy_id, int loc,
                              int val)
{
        struct usbnet *dev = netdev_priv(netdev);
        __le16 res = cpu_to_le16(val);

        if (phy_id) {
                netdev_dbg(dev->net, "Only internal phy supported\n");
                return;
        }

        netdev_dbg(dev->net, "dm9601_mdio_write() phy_id=0x%02x, loc=0x%02x, val=0x%04x\n",
                   phy_id, loc, val);

        dm_write_shared_word(dev, 1, loc, res);
}

static const struct ethtool_ops dm9601_ethtool_ops = {
        .get_drvinfo    = usbnet_get_drvinfo,
        .get_link       = usbnet_get_link,
        .get_msglevel   = usbnet_get_msglevel,
        .set_msglevel   = usbnet_set_msglevel,
        .get_eeprom_len = dm9601_get_eeprom_len,
        .get_eeprom     = dm9601_get_eeprom,
        .nway_reset     = usbnet_nway_reset,
        .get_link_ksettings     = usbnet_get_link_ksettings_mii,
        .set_link_ksettings     = usbnet_set_link_ksettings_mii,
};

static void dm9601_set_multicast(struct net_device *net)
{
        struct usbnet *dev = netdev_priv(net);
        /* We use the 20 byte dev->data for our 8 byte filter buffer
         * to avoid allocating memory that is tricky to free later */
        u8 *hashes = (u8 *) & dev->data;
        u8 rx_ctl = 0x31;

        memset(hashes, 0x00, DM_MCAST_SIZE);
        hashes[DM_MCAST_SIZE - 1] |= 0x80;      /* broadcast address */

        if (net->flags & IFF_PROMISC) {
                rx_ctl |= 0x02;
        } else if (net->flags & IFF_ALLMULTI ||
                   netdev_mc_count(net) > DM_MAX_MCAST) {
                rx_ctl |= 0x08;
        } else if (!netdev_mc_empty(net)) {
                struct netdev_hw_addr *ha;

                netdev_for_each_mc_addr(ha, net) {
                        u32 crc = ether_crc(ETH_ALEN, ha->addr) >> 26;
                        hashes[crc >> 3] |= 1 << (crc & 0x7);
                }
        }

        dm_write_async(dev, DM_MCAST_ADDR, DM_MCAST_SIZE, hashes);
        dm_write_reg_async(dev, DM_RX_CTRL, rx_ctl);
}

static void __dm9601_set_mac_address(struct usbnet *dev)
{
        dm_write_async(dev, DM_PHY_ADDR, ETH_ALEN, dev->net->dev_addr);
}

static int dm9601_set_mac_address(struct net_device *net, void *p)
{
        struct sockaddr *addr = p;
        struct usbnet *dev = netdev_priv(net);

        if (!is_valid_ether_addr(addr->sa_data)) {
                dev_err(&net->dev, "not setting invalid mac address %pM\n",
                                                                addr->sa_data);
                return -EINVAL;
        }

        eth_hw_addr_set(net, addr->sa_data);
        __dm9601_set_mac_address(dev);

        return 0;
}

static const struct net_device_ops dm9601_netdev_ops = {
        .ndo_open               = usbnet_open,
        .ndo_stop               = usbnet_stop,
        .ndo_start_xmit         = usbnet_start_xmit,
        .ndo_tx_timeout         = usbnet_tx_timeout,
        .ndo_change_mtu         = usbnet_change_mtu,
        .ndo_get_stats64        = dev_get_tstats64,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_eth_ioctl          = usbnet_mii_ioctl,
        .ndo_set_rx_mode        = dm9601_set_multicast,
        .ndo_set_mac_address    = dm9601_set_mac_address,
};

static int dm9601_bind(struct usbnet *dev, struct usb_interface *intf)
{
        int ret;
        u8 mac[ETH_ALEN], id;

        ret = usbnet_get_endpoints(dev, intf);
        if (ret)
                goto out;

        dev->net->netdev_ops = &dm9601_netdev_ops;
        dev->net->ethtool_ops = &dm9601_ethtool_ops;
        dev->net->hard_header_len += DM_TX_OVERHEAD;
        dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;

        /* dm9620/21a require room for 4 byte padding, even in dm9601
         * mode, so we need +1 to be able to receive full size
         * ethernet frames.
         */
        dev->rx_urb_size = dev->net->mtu + ETH_HLEN + DM_RX_OVERHEAD + 1;

        dev->mii.dev = dev->net;
        dev->mii.mdio_read = dm9601_mdio_read;
        dev->mii.mdio_write = dm9601_mdio_write;
        dev->mii.phy_id_mask = 0x1f;
        dev->mii.reg_num_mask = 0x1f;

        /* reset */
        dm_write_reg(dev, DM_NET_CTRL, 1);
        udelay(20);

        /* read MAC */
        if (dm_read(dev, DM_PHY_ADDR, ETH_ALEN, mac) < 0) {
                printk(KERN_ERR "Error reading MAC address\n");
                ret = -ENODEV;
                goto out;
        }

        /*
         * Overwrite the auto-generated address only with good ones.
         */
        if (is_valid_ether_addr(mac))
                eth_hw_addr_set(dev->net, mac);
        else {
                printk(KERN_WARNING
                        "dm9601: No valid MAC address in EEPROM, using %pM\n",
                        dev->net->dev_addr);
                __dm9601_set_mac_address(dev);
        }

        if (dm_read_reg(dev, DM_CHIP_ID, &id) < 0) {
                netdev_err(dev->net, "Error reading chip ID\n");
                ret = -ENODEV;
                goto out;
        }

        /* put dm9620 devices in dm9601 mode */
        if (id == ID_DM9620) {
                u8 mode;

                if (dm_read_reg(dev, DM_MODE_CTRL, &mode) < 0) {
                        netdev_err(dev->net, "Error reading MODE_CTRL\n");
                        ret = -ENODEV;
                        goto out;
                }
                dm_write_reg(dev, DM_MODE_CTRL, mode & 0x7f);
        }

        /* power up phy */
        dm_write_reg(dev, DM_GPR_CTRL, 1);
        dm_write_reg(dev, DM_GPR_DATA, 0);

        /* receive broadcast packets */
        dm9601_set_multicast(dev->net);

        dm9601_mdio_write(dev->net, dev->mii.phy_id, MII_BMCR, BMCR_RESET);
        dm9601_mdio_write(dev->net, dev->mii.phy_id, MII_ADVERTISE,
                          ADVERTISE_ALL | ADVERTISE_CSMA | ADVERTISE_PAUSE_CAP);
        mii_nway_restart(&dev->mii);

out:
        return ret;
}

static int dm9601_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
        u8 status;
        int len;

        /* format:
           b1: rx status
           b2: packet length (incl crc) low
           b3: packet length (incl crc) high
           b4..n-4: packet data
           bn-3..bn: ethernet crc
         */

        if (unlikely(skb->len < DM_RX_OVERHEAD)) {
                dev_err(&dev->udev->dev, "unexpected tiny rx frame\n");
                return 0;
        }

        status = skb->data[0];
        len = (skb->data[1] | (skb->data[2] << 8)) - 4;

        if (unlikely(status & 0xbf)) {
                if (status & 0x01) dev->net->stats.rx_fifo_errors++;
                if (status & 0x02) dev->net->stats.rx_crc_errors++;
                if (status & 0x04) dev->net->stats.rx_frame_errors++;
                if (status & 0x20) dev->net->stats.rx_missed_errors++;
                if (status & 0x90) dev->net->stats.rx_length_errors++;
                return 0;
        }

        skb_pull(skb, 3);
        skb_trim(skb, len);

        return 1;
}

static struct sk_buff *dm9601_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
                                       gfp_t flags)
{
        int len, pad;

        /* format:
           b1: packet length low
           b2: packet length high
           b3..n: packet data
        */

        len = skb->len + DM_TX_OVERHEAD;

        /* workaround for dm962x errata with tx fifo getting out of
         * sync if a USB bulk transfer retry happens right after a
         * packet with odd / maxpacket length by adding up to 3 bytes
         * padding.
         */
        while ((len & 1) || !(len % dev->maxpacket))
                len++;

        len -= DM_TX_OVERHEAD; /* hw header doesn't count as part of length */
        pad = len - skb->len;

        if (skb_headroom(skb) < DM_TX_OVERHEAD || skb_tailroom(skb) < pad) {
                struct sk_buff *skb2;

                skb2 = skb_copy_expand(skb, DM_TX_OVERHEAD, pad, flags);
                dev_kfree_skb_any(skb);
                skb = skb2;
                if (!skb)
                        return NULL;
        }

        __skb_push(skb, DM_TX_OVERHEAD);

        if (pad) {
                memset(skb->data + skb->len, 0, pad);
                __skb_put(skb, pad);
        }

        skb->data[0] = len;
        skb->data[1] = len >> 8;

        return skb;
}

static void dm9601_status(struct usbnet *dev, struct urb *urb)
{
        int link;
        u8 *buf;

        /* format:
           b0: net status
           b1: tx status 1
           b2: tx status 2
           b3: rx status
           b4: rx overflow
           b5: rx count
           b6: tx count
           b7: gpr
        */

        if (urb->actual_length < 8)
                return;

        buf = urb->transfer_buffer;

        link = !!(buf[0] & 0x40);
        if (netif_carrier_ok(dev->net) != link) {
                usbnet_link_change(dev, link, 1);
                netdev_dbg(dev->net, "Link Status is: %d\n", link);
        }
}

static int dm9601_link_reset(struct usbnet *dev)
{
        struct ethtool_cmd ecmd = { .cmd = ETHTOOL_GSET };

        mii_check_media(&dev->mii, 1, 1);
        mii_ethtool_gset(&dev->mii, &ecmd);

        netdev_dbg(dev->net, "link_reset() speed: %u duplex: %d\n",
                   ethtool_cmd_speed(&ecmd), ecmd.duplex);

        return 0;
}

static const struct driver_info dm9601_info = {
        .description    = "Davicom DM96xx USB 10/100 Ethernet",
        .flags          = FLAG_ETHER | FLAG_LINK_INTR,
        .bind           = dm9601_bind,
        .rx_fixup       = dm9601_rx_fixup,
        .tx_fixup       = dm9601_tx_fixup,
        .status         = dm9601_status,
        .link_reset     = dm9601_link_reset,
        .reset          = dm9601_link_reset,
};

static const struct usb_device_id products[] = {
        {
         USB_DEVICE(0x07aa, 0x9601),    /* Corega FEther USB-TXC */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x9601),    /* Davicom USB-100 */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x6688),    /* ZT6688 USB NIC */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x0268),    /* ShanTou ST268 USB NIC */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x8515),    /* ADMtek ADM8515 USB NIC */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
        USB_DEVICE(0x0a47, 0x9601),     /* Hirose USB-100 */
        .driver_info = (unsigned long)&dm9601_info,
         },
        {
        USB_DEVICE(0x0fe6, 0x8101),     /* DM9601 USB to Fast Ethernet Adapter */
        .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x9000),    /* DM9000E */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x9620),    /* DM9620 USB to Fast Ethernet Adapter */
         .driver_info = (unsigned long)&dm9601_info,
         },
        {
         USB_DEVICE(0x0a46, 0x9621),    /* DM9621A USB to Fast Ethernet Adapter */
         .driver_info = (unsigned long)&dm9601_info,
        },
        {
         USB_DEVICE(0x0a46, 0x9622),    /* DM9622 USB to Fast Ethernet Adapter */
         .driver_info = (unsigned long)&dm9601_info,
        },
        {
         USB_DEVICE(0x0a46, 0x0269),    /* DM962OA USB to Fast Ethernet Adapter */
         .driver_info = (unsigned long)&dm9601_info,
        },
        {
         USB_DEVICE(0x0a46, 0x1269),    /* DM9621A USB to Fast Ethernet Adapter */
         .driver_info = (unsigned long)&dm9601_info,
        },
        {
         USB_DEVICE(0x0586, 0x3427),    /* ZyXEL Keenetic Plus DSL xDSL modem */
         .driver_info = (unsigned long)&dm9601_info,
        },
        {},                     // END
};

MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver dm9601_driver = {
        .name = "dm9601",
        .id_table = products,
        .probe = usbnet_probe,
        .disconnect = usbnet_disconnect,
        .suspend = usbnet_suspend,
        .resume = usbnet_resume,
        .disable_hub_initiated_lpm = 1,
};

module_usb_driver(dm9601_driver);

MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
MODULE_DESCRIPTION("Davicom DM96xx USB 10/100 ethernet devices");
MODULE_LICENSE("GPL");