/*
 * MOSCHIP MCS7830 based (7730/7830/7832) USB 2.0 Ethernet Devices
 *
 * based on usbnet.c, asix.c and the vendor provided mcs7830 driver
 *
 * Copyright (C) 2010 Andreas Mohr <andi@lisas.de>
 * Copyright (C) 2006 Arnd Bergmann <arnd@arndb.de>
 * Copyright (C) 2003-2005 David Hollis <dhollis@davehollis.com>
 * Copyright (C) 2005 Phil Chang <pchang23@sbcglobal.net>
 * Copyright (c) 2002-2003 TiVo Inc.
 *
 * Definitions gathered from MOSCHIP, Data Sheet_7830DA.pdf (thanks!).
 *
 * 2010-12-19: add 7832 USB PID ("functionality same as MCS7830"),
 *             per active notification by manufacturer
 *
 * TODO:
 * - support HIF_REG_CONFIG_SLEEPMODE/HIF_REG_CONFIG_TXENABLE (via autopm?)
 * - implement ethtool_ops get_pauseparam/set_pauseparam
 *   via HIF_REG_PAUSE_THRESHOLD (>= revision C only!)
 * - implement get_eeprom/[set_eeprom]
 * - switch PHY on/off on ifup/ifdown (perhaps in usbnet.c, via MII)
 * - mcs7830_get_regs() handling is weird: for rev 2 we return 32 regs,
 *   can access only ~ 24, remaining user buffer is uninitialized garbage
 * - anything else?
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

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

/* requests */
#define MCS7830_RD_BMREQ        (USB_DIR_IN  | USB_TYPE_VENDOR | \
                                 USB_RECIP_DEVICE)
#define MCS7830_WR_BMREQ        (USB_DIR_OUT | USB_TYPE_VENDOR | \
                                 USB_RECIP_DEVICE)
#define MCS7830_RD_BREQ         0x0E
#define MCS7830_WR_BREQ         0x0D

#define MCS7830_CTRL_TIMEOUT    1000
#define MCS7830_MAX_MCAST       64

#define MCS7830_VENDOR_ID       0x9710
#define MCS7832_PRODUCT_ID      0x7832
#define MCS7830_PRODUCT_ID      0x7830
#define MCS7730_PRODUCT_ID      0x7730

#define SITECOM_VENDOR_ID       0x0DF6
#define LN_030_PRODUCT_ID       0x0021

#define MCS7830_MII_ADVERTISE   (ADVERTISE_PAUSE_CAP | ADVERTISE_100FULL | \
                                 ADVERTISE_100HALF | ADVERTISE_10FULL | \
                                 ADVERTISE_10HALF | ADVERTISE_CSMA)

/* HIF_REG_XX corresponding index value */
enum {
        HIF_REG_MULTICAST_HASH                  = 0x00,
        HIF_REG_PACKET_GAP1                     = 0x08,
        HIF_REG_PACKET_GAP2                     = 0x09,
        HIF_REG_PHY_DATA                        = 0x0a,
        HIF_REG_PHY_CMD1                        = 0x0c,
           HIF_REG_PHY_CMD1_READ                = 0x40,
           HIF_REG_PHY_CMD1_WRITE               = 0x20,
           HIF_REG_PHY_CMD1_PHYADDR             = 0x01,
        HIF_REG_PHY_CMD2                        = 0x0d,
           HIF_REG_PHY_CMD2_PEND_FLAG_BIT       = 0x80,
           HIF_REG_PHY_CMD2_READY_FLAG_BIT      = 0x40,
        HIF_REG_CONFIG                          = 0x0e,
        /* hmm, spec sez: "R/W", "Except bit 3" (likely TXENABLE). */
           HIF_REG_CONFIG_CFG                   = 0x80,
           HIF_REG_CONFIG_SPEED100              = 0x40,
           HIF_REG_CONFIG_FULLDUPLEX_ENABLE     = 0x20,
           HIF_REG_CONFIG_RXENABLE              = 0x10,
           HIF_REG_CONFIG_TXENABLE              = 0x08,
           HIF_REG_CONFIG_SLEEPMODE             = 0x04,
           HIF_REG_CONFIG_ALLMULTICAST          = 0x02,
           HIF_REG_CONFIG_PROMISCUOUS           = 0x01,
        HIF_REG_ETHERNET_ADDR                   = 0x0f,
        HIF_REG_FRAME_DROP_COUNTER              = 0x15, /* 0..ff; reset: 0 */
        HIF_REG_PAUSE_THRESHOLD                 = 0x16,
           HIF_REG_PAUSE_THRESHOLD_DEFAULT      = 0,
};

/* Trailing status byte in Ethernet Rx frame */
enum {
        MCS7830_RX_SHORT_FRAME          = 0x01, /* < 64 bytes */
        MCS7830_RX_LENGTH_ERROR         = 0x02, /* framelen != Ethernet length field */
        MCS7830_RX_ALIGNMENT_ERROR      = 0x04, /* non-even number of nibbles */
        MCS7830_RX_CRC_ERROR            = 0x08,
        MCS7830_RX_LARGE_FRAME          = 0x10, /* > 1518 bytes */
        MCS7830_RX_FRAME_CORRECT        = 0x20, /* frame is correct */
        /* [7:6] reserved */
};

struct mcs7830_data {
        u8 multi_filter[8];
        u8 config;
};

static const char driver_name[] = "MOSCHIP usb-ethernet driver";

static int mcs7830_get_reg(struct usbnet *dev, u16 index, u16 size, void *data)
{
        return usbnet_read_cmd(dev, MCS7830_RD_BREQ, MCS7830_RD_BMREQ,
                                0x0000, index, data, size);
}

static int mcs7830_set_reg(struct usbnet *dev, u16 index, u16 size, const void *data)
{
        return usbnet_write_cmd(dev, MCS7830_WR_BREQ, MCS7830_WR_BMREQ,
                                0x0000, index, data, size);
}

static void mcs7830_set_reg_async(struct usbnet *dev, u16 index, u16 size, void *data)
{
        usbnet_write_cmd_async(dev, MCS7830_WR_BREQ, MCS7830_WR_BMREQ,
                                0x0000, index, data, size);
}

static int mcs7830_hif_get_mac_address(struct usbnet *dev, unsigned char *addr)
{
        int ret = mcs7830_get_reg(dev, HIF_REG_ETHERNET_ADDR, ETH_ALEN, addr);
        if (ret < 0)
                return ret;
        return 0;
}

static int mcs7830_hif_set_mac_address(struct usbnet *dev, unsigned char *addr)
{
        int ret = mcs7830_set_reg(dev, HIF_REG_ETHERNET_ADDR, ETH_ALEN, addr);

        if (ret < 0)
                return ret;
        return 0;
}

static int mcs7830_set_mac_address(struct net_device *netdev, void *p)
{
        int ret;
        struct usbnet *dev = netdev_priv(netdev);
        struct sockaddr *addr = p;

        if (netif_running(netdev))
                return -EBUSY;

        if (!is_valid_ether_addr(addr->sa_data))
                return -EADDRNOTAVAIL;

        ret = mcs7830_hif_set_mac_address(dev, addr->sa_data);

        if (ret < 0)
                return ret;

        /* it worked --> adopt it on netdev side */
        memcpy(netdev->dev_addr, addr->sa_data, netdev->addr_len);

        return 0;
}

static int mcs7830_read_phy(struct usbnet *dev, u8 index)
{
        int ret;
        int i;
        __le16 val;

        u8 cmd[2] = {
                HIF_REG_PHY_CMD1_READ | HIF_REG_PHY_CMD1_PHYADDR,
                HIF_REG_PHY_CMD2_PEND_FLAG_BIT | index,
        };

        mutex_lock(&dev->phy_mutex);
        /* write the MII command */
        ret = mcs7830_set_reg(dev, HIF_REG_PHY_CMD1, 2, cmd);
        if (ret < 0)
                goto out;

        /* wait for the data to become valid, should be within < 1ms */
        for (i = 0; i < 10; i++) {
                ret = mcs7830_get_reg(dev, HIF_REG_PHY_CMD1, 2, cmd);
                if ((ret < 0) || (cmd[1] & HIF_REG_PHY_CMD2_READY_FLAG_BIT))
                        break;
                ret = -EIO;
                msleep(1);
        }
        if (ret < 0)
                goto out;

        /* read actual register contents */
        ret = mcs7830_get_reg(dev, HIF_REG_PHY_DATA, 2, &val);
        if (ret < 0)
                goto out;
        ret = le16_to_cpu(val);
        dev_dbg(&dev->udev->dev, "read PHY reg %02x: %04x (%d tries)\n",
                index, val, i);
out:
        mutex_unlock(&dev->phy_mutex);
        return ret;
}

static int mcs7830_write_phy(struct usbnet *dev, u8 index, u16 val)
{
        int ret;
        int i;
        __le16 le_val;

        u8 cmd[2] = {
                HIF_REG_PHY_CMD1_WRITE | HIF_REG_PHY_CMD1_PHYADDR,
                HIF_REG_PHY_CMD2_PEND_FLAG_BIT | (index & 0x1F),
        };

        mutex_lock(&dev->phy_mutex);

        /* write the new register contents */
        le_val = cpu_to_le16(val);
        ret = mcs7830_set_reg(dev, HIF_REG_PHY_DATA, 2, &le_val);
        if (ret < 0)
                goto out;

        /* write the MII command */
        ret = mcs7830_set_reg(dev, HIF_REG_PHY_CMD1, 2, cmd);
        if (ret < 0)
                goto out;

        /* wait for the command to be accepted by the PHY */
        for (i = 0; i < 10; i++) {
                ret = mcs7830_get_reg(dev, HIF_REG_PHY_CMD1, 2, cmd);
                if ((ret < 0) || (cmd[1] & HIF_REG_PHY_CMD2_READY_FLAG_BIT))
                        break;
                ret = -EIO;
                msleep(1);
        }
        if (ret < 0)
                goto out;

        ret = 0;
        dev_dbg(&dev->udev->dev, "write PHY reg %02x: %04x (%d tries)\n",
                index, val, i);
out:
        mutex_unlock(&dev->phy_mutex);
        return ret;
}

/*
 * This algorithm comes from the original mcs7830 version 1.4 driver,
 * not sure if it is needed.
 */
static int mcs7830_set_autoneg(struct usbnet *dev, int ptrUserPhyMode)
{
        int ret;
        /* Enable all media types */
        ret = mcs7830_write_phy(dev, MII_ADVERTISE, MCS7830_MII_ADVERTISE);

        /* First reset BMCR */
        if (!ret)
                ret = mcs7830_write_phy(dev, MII_BMCR, 0x0000);
        /* Enable Auto Neg */
        if (!ret)
                ret = mcs7830_write_phy(dev, MII_BMCR, BMCR_ANENABLE);
        /* Restart Auto Neg (Keep the Enable Auto Neg Bit Set) */
        if (!ret)
                ret = mcs7830_write_phy(dev, MII_BMCR,
                                BMCR_ANENABLE | BMCR_ANRESTART  );
        return ret;
}


/*
 * if we can read register 22, the chip revision is C or higher
 */
static int mcs7830_get_rev(struct usbnet *dev)
{
        u8 dummy[2];
        int ret;
        ret = mcs7830_get_reg(dev, HIF_REG_FRAME_DROP_COUNTER, 2, dummy);
        if (ret > 0)
                return 2; /* Rev C or later */
        return 1; /* earlier revision */
}

/*
 * On rev. C we need to set the pause threshold
 */
static void mcs7830_rev_C_fixup(struct usbnet *dev)
{
        u8 pause_threshold = HIF_REG_PAUSE_THRESHOLD_DEFAULT;
        int retry;

        for (retry = 0; retry < 2; retry++) {
                if (mcs7830_get_rev(dev) == 2) {
                        dev_info(&dev->udev->dev, "applying rev.C fixup\n");
                        mcs7830_set_reg(dev, HIF_REG_PAUSE_THRESHOLD,
                                        1, &pause_threshold);
                }
                msleep(1);
        }
}

static int mcs7830_mdio_read(struct net_device *netdev, int phy_id,
                             int location)
{
        struct usbnet *dev = netdev_priv(netdev);
        return mcs7830_read_phy(dev, location);
}

static void mcs7830_mdio_write(struct net_device *netdev, int phy_id,
                                int location, int val)
{
        struct usbnet *dev = netdev_priv(netdev);
        mcs7830_write_phy(dev, location, val);
}

static int mcs7830_ioctl(struct net_device *net, struct ifreq *rq, int cmd)
{
        struct usbnet *dev = netdev_priv(net);
        return generic_mii_ioctl(&dev->mii, if_mii(rq), cmd, NULL);
}

static inline struct mcs7830_data *mcs7830_get_data(struct usbnet *dev)
{
        return (struct mcs7830_data *)&dev->data;
}

static void mcs7830_hif_update_multicast_hash(struct usbnet *dev)
{
        struct mcs7830_data *data = mcs7830_get_data(dev);
        mcs7830_set_reg_async(dev, HIF_REG_MULTICAST_HASH,
                                sizeof data->multi_filter,
                                data->multi_filter);
}

static void mcs7830_hif_update_config(struct usbnet *dev)
{
        /* implementation specific to data->config
           (argument needs to be heap-based anyway - USB DMA!) */
        struct mcs7830_data *data = mcs7830_get_data(dev);
        mcs7830_set_reg_async(dev, HIF_REG_CONFIG, 1, &data->config);
}

static void mcs7830_data_set_multicast(struct net_device *net)
{
        struct usbnet *dev = netdev_priv(net);
        struct mcs7830_data *data = mcs7830_get_data(dev);

        memset(data->multi_filter, 0, sizeof data->multi_filter);

        data->config = HIF_REG_CONFIG_TXENABLE;

        /* this should not be needed, but it doesn't work otherwise */
        data->config |= HIF_REG_CONFIG_ALLMULTICAST;

        if (net->flags & IFF_PROMISC) {
                data->config |= HIF_REG_CONFIG_PROMISCUOUS;
        } else if (net->flags & IFF_ALLMULTI ||
                   netdev_mc_count(net) > MCS7830_MAX_MCAST) {
                data->config |= HIF_REG_CONFIG_ALLMULTICAST;
        } else if (netdev_mc_empty(net)) {
                /* just broadcast and directed */
        } else {
                /* We use the 20 byte dev->data
                 * for our 8 byte filter buffer
                 * to avoid allocating memory that
                 * is tricky to free later */
                struct netdev_hw_addr *ha;
                u32 crc_bits;

                /* Build the multicast hash filter. */
                netdev_for_each_mc_addr(ha, net) {
                        crc_bits = ether_crc(ETH_ALEN, ha->addr) >> 26;
                        data->multi_filter[crc_bits >> 3] |= 1 << (crc_bits & 7);
                }
        }
}

static int mcs7830_apply_base_config(struct usbnet *dev)
{
        int ret;

        /* re-configure known MAC (suspend case etc.) */
        ret = mcs7830_hif_set_mac_address(dev, dev->net->dev_addr);
        if (ret) {
                dev_info(&dev->udev->dev, "Cannot set MAC address\n");
                goto out;
        }

        /* Set up PHY */
        ret = mcs7830_set_autoneg(dev, 0);
        if (ret) {
                dev_info(&dev->udev->dev, "Cannot set autoneg\n");
                goto out;
        }

        mcs7830_hif_update_multicast_hash(dev);
        mcs7830_hif_update_config(dev);

        mcs7830_rev_C_fixup(dev);
        ret = 0;
out:
        return ret;
}

/* credits go to asix_set_multicast */
static void mcs7830_set_multicast(struct net_device *net)
{
        struct usbnet *dev = netdev_priv(net);

        mcs7830_data_set_multicast(net);

        mcs7830_hif_update_multicast_hash(dev);
        mcs7830_hif_update_config(dev);
}

static int mcs7830_get_regs_len(struct net_device *net)
{
        struct usbnet *dev = netdev_priv(net);

        switch (mcs7830_get_rev(dev)) {
        case 1:
                return 21;
        case 2:
                return 32;
        }
        return 0;
}

static void mcs7830_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *drvinfo)
{
        usbnet_get_drvinfo(net, drvinfo);
}

static void mcs7830_get_regs(struct net_device *net, struct ethtool_regs *regs, void *data)
{
        struct usbnet *dev = netdev_priv(net);

        regs->version = mcs7830_get_rev(dev);
        mcs7830_get_reg(dev, 0, regs->len, data);
}

static const struct ethtool_ops mcs7830_ethtool_ops = {
        .get_drvinfo            = mcs7830_get_drvinfo,
        .get_regs_len           = mcs7830_get_regs_len,
        .get_regs               = mcs7830_get_regs,

        /* common usbnet calls */
        .get_link               = usbnet_get_link,
        .get_msglevel           = usbnet_get_msglevel,
        .set_msglevel           = usbnet_set_msglevel,
        .get_settings           = usbnet_get_settings,
        .set_settings           = usbnet_set_settings,
        .nway_reset             = usbnet_nway_reset,
};

static const struct net_device_ops mcs7830_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_validate_addr      = eth_validate_addr,
        .ndo_do_ioctl           = mcs7830_ioctl,
        .ndo_set_rx_mode        = mcs7830_set_multicast,
        .ndo_set_mac_address    = mcs7830_set_mac_address,
};

static int mcs7830_bind(struct usbnet *dev, struct usb_interface *udev)
{
        struct net_device *net = dev->net;
        int ret;
        int retry;

        /* Initial startup: Gather MAC address setting from EEPROM */
        ret = -EINVAL;
        for (retry = 0; retry < 5 && ret; retry++)
                ret = mcs7830_hif_get_mac_address(dev, net->dev_addr);
        if (ret) {
                dev_warn(&dev->udev->dev, "Cannot read MAC address\n");
                goto out;
        }

        mcs7830_data_set_multicast(net);

        ret = mcs7830_apply_base_config(dev);
        if (ret)
                goto out;

        net->ethtool_ops = &mcs7830_ethtool_ops;
        net->netdev_ops = &mcs7830_netdev_ops;

        /* reserve space for the status byte on rx */
        dev->rx_urb_size = ETH_FRAME_LEN + 1;

        dev->mii.mdio_read = mcs7830_mdio_read;
        dev->mii.mdio_write = mcs7830_mdio_write;
        dev->mii.dev = net;
        dev->mii.phy_id_mask = 0x3f;
        dev->mii.reg_num_mask = 0x1f;
        dev->mii.phy_id = *((u8 *) net->dev_addr + 1);

        ret = usbnet_get_endpoints(dev, udev);
out:
        return ret;
}

/* The chip always appends a status byte that we need to strip */
static int mcs7830_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
        u8 status;

        /* This check is no longer done by usbnet */
        if (skb->len < dev->net->hard_header_len) {
                dev_err(&dev->udev->dev, "unexpected tiny rx frame\n");
                return 0;
        }

        skb_trim(skb, skb->len - 1);
        status = skb->data[skb->len];

        if (status != MCS7830_RX_FRAME_CORRECT) {
                dev_dbg(&dev->udev->dev, "rx fixup status %x\n", status);

                /* hmm, perhaps usbnet.c already sees a globally visible
                   frame error and increments rx_errors on its own already? */
                dev->net->stats.rx_errors++;

                if (status &    (MCS7830_RX_SHORT_FRAME
                                |MCS7830_RX_LENGTH_ERROR
                                |MCS7830_RX_LARGE_FRAME))
                        dev->net->stats.rx_length_errors++;
                if (status & MCS7830_RX_ALIGNMENT_ERROR)
                        dev->net->stats.rx_frame_errors++;
                if (status & MCS7830_RX_CRC_ERROR)
                        dev->net->stats.rx_crc_errors++;
        }

        return skb->len > 0;
}

static void mcs7830_status(struct usbnet *dev, struct urb *urb)
{
        u8 *buf = urb->transfer_buffer;
        bool link, link_changed;

        if (urb->actual_length < 16)
                return;

        link = !(buf[1] == 0x20);
        link_changed = netif_carrier_ok(dev->net) != link;
        if (link_changed) {
                usbnet_link_change(dev, link, 0);
                netdev_dbg(dev->net, "Link Status is: %d\n", link);
        }
}

static const struct driver_info moschip_info = {
        .description    = "MOSCHIP 7830/7832/7730 usb-NET adapter",
        .bind           = mcs7830_bind,
        .rx_fixup       = mcs7830_rx_fixup,
        .flags          = FLAG_ETHER | FLAG_LINK_INTR,
        .status         = mcs7830_status,
        .in             = 1,
        .out            = 2,
};

static const struct driver_info sitecom_info = {
        .description    = "Sitecom LN-30 usb-NET adapter",
        .bind           = mcs7830_bind,
        .rx_fixup       = mcs7830_rx_fixup,
        .flags          = FLAG_ETHER | FLAG_LINK_INTR,
        .status         = mcs7830_status,
        .in             = 1,
        .out            = 2,
};

static const struct usb_device_id products[] = {
        {
                USB_DEVICE(MCS7830_VENDOR_ID, MCS7832_PRODUCT_ID),
                .driver_info = (unsigned long) &moschip_info,
        },
        {
                USB_DEVICE(MCS7830_VENDOR_ID, MCS7830_PRODUCT_ID),
                .driver_info = (unsigned long) &moschip_info,
        },
        {
                USB_DEVICE(MCS7830_VENDOR_ID, MCS7730_PRODUCT_ID),
                .driver_info = (unsigned long) &moschip_info,
        },
        {
                USB_DEVICE(SITECOM_VENDOR_ID, LN_030_PRODUCT_ID),
                .driver_info = (unsigned long) &sitecom_info,
        },
        {},
};
MODULE_DEVICE_TABLE(usb, products);

static int mcs7830_reset_resume (struct usb_interface *intf)
{
        /* YES, this function is successful enough that ethtool -d
           does show same output pre-/post-suspend */

        struct usbnet           *dev = usb_get_intfdata(intf);

        mcs7830_apply_base_config(dev);

        usbnet_resume(intf);

        return 0;
}

static struct usb_driver mcs7830_driver = {
        .name = driver_name,
        .id_table = products,
        .probe = usbnet_probe,
        .disconnect = usbnet_disconnect,
        .suspend = usbnet_suspend,
        .resume = usbnet_resume,
        .reset_resume = mcs7830_reset_resume,
        .disable_hub_initiated_lpm = 1,
};

module_usb_driver(mcs7830_driver);

MODULE_DESCRIPTION("USB to network adapter MCS7830)");
MODULE_LICENSE("GPL");