/*
 * CoreChip-sz SR9700 one chip USB 1.1 Ethernet Devices
 *
 * Author : Liu Junliang <liujunliang_ljl@163.com>
 *
 * Based on dm9601.c
 *
 * 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.
 */

#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/usb.h>
#include <linux/usb/usbnet.h>

#include "sr9700.h"

static int sr_read(struct usbnet *dev, u8 reg, u16 length, void *data)
{
        int err;

        err = usbnet_read_cmd(dev, SR_RD_REGS, SR_REQ_RD_REG, 0, reg, data,
                              length);
        if ((err != length) && (err >= 0))
                err = -EINVAL;
        return err;
}

static int sr_write(struct usbnet *dev, u8 reg, u16 length, void *data)
{
        int err;

        err = usbnet_write_cmd(dev, SR_WR_MULTIPLE_REGS, SR_REQ_WR_REG, 0, reg, data,
                               length);
        if ((err >= 0) && (err < length))
                err = -EINVAL;
        return err;
}

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

static int sr_write_reg(struct usbnet *dev, u8 reg, u8 value)
{
        return usbnet_write_cmd(dev, SR_WR_SINGLE_REG, SR_REQ_WR_REG,
                                value, reg, NULL, 0);
}

static void sr_write_async(struct usbnet *dev, u8 reg, u16 length,
                           const void *data)
{
        usbnet_write_cmd_async(dev, SR_WR_MULTIPLE_REGS, SR_REQ_WR_REG,
                               0, reg, data, length);
}

static void sr_write_reg_async(struct usbnet *dev, u8 reg, u8 value)
{
        usbnet_write_cmd_async(dev, SR_WR_SINGLE_REG, SR_REQ_WR_REG,
                               value, reg, NULL, 0);
}

static int wait_eeprom_ready(struct usbnet *dev)
{
        int i;

        for (i = 0; i < SR_EEPROM_TIMEOUT; i++) {
                u8 tmp = 0;
                int ret;

                udelay(1);
                ret = sr_read_reg(dev, SR_EPCR, &tmp);
                if (ret < 0)
                        return ret;

                /* ready */
                if (!(tmp & EPCR_ERRE))
                        return 0;
        }

        netdev_err(dev->net, "eeprom write timed out!\n");

        return -EIO;
}

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

        mutex_lock(&dev->phy_mutex);

        sr_write_reg(dev, SR_EPAR, reg);
        sr_write_reg(dev, SR_EPCR, EPCR_ERPRR);

        ret = wait_eeprom_ready(dev);
        if (ret < 0)
                goto out_unlock;

        sr_write_reg(dev, SR_EPCR, 0x0);
        ret = sr_read(dev, SR_EPDR, 2, value);

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

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

static int __maybe_unused sr_write_eeprom_word(struct usbnet *dev, u8 reg,
                                               __le16 value)
{
        int ret;

        mutex_lock(&dev->phy_mutex);

        ret = sr_write(dev, SR_EPDR, 2, &value);
        if (ret < 0)
                goto out_unlock;

        sr_write_reg(dev, SR_EPAR, reg);
        sr_write_reg(dev, SR_EPCR, EPCR_WEP | EPCR_ERPRW);

        ret = wait_eeprom_ready(dev);
        if (ret < 0)
                goto out_unlock;

        sr_write_reg(dev, SR_EPCR, 0x0);

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

static int sr9700_get_eeprom_len(struct net_device *netdev)
{
        return SR_EEPROM_LEN;
}

static int sr9700_get_eeprom(struct net_device *netdev,
                             struct ethtool_eeprom *eeprom, u8 *data)
{
        struct usbnet *dev = netdev_priv(netdev);
        __le16 *buf = (__le16 *)data;
        int ret = 0;
        int i;

        /* access is 16bit */
        if ((eeprom->offset & 0x01) || (eeprom->len & 0x01))
                return -EINVAL;

        for (i = 0; i < eeprom->len / 2; i++) {
                ret = sr_read_eeprom_word(dev, eeprom->offset / 2 + i, buf + i);
                if (ret < 0)
                        break;
        }

        return ret;
}

static void sr9700_handle_link_change(struct net_device *netdev, bool link)
{
        if (netif_carrier_ok(netdev) != link) {
                if (link) {
                        netif_carrier_on(netdev);
                        netdev_info(netdev, "link up, 10Mbps, half-duplex\n");
                } else {
                        netif_carrier_off(netdev);
                        netdev_info(netdev, "link down\n");
                }
        }
}

static u32 sr9700_get_link(struct net_device *netdev)
{
        struct usbnet *dev = netdev_priv(netdev);
        u8 value = 0;
        u32 link = 0;

        sr_read_reg(dev, SR_NSR, &value);
        link = !!(value & NSR_LINKST);

        sr9700_handle_link_change(netdev, link);

        return link;
}

/*
 * The device supports only 10Mbps half-duplex operation. It implements the
 * DM9601 speed/duplex status registers, but as the values are always the same,
 * using them would add unnecessary complexity.
 */
static int sr9700_get_link_ksettings(struct net_device *dev,
                                     struct ethtool_link_ksettings *cmd)
{
        ethtool_link_ksettings_zero_link_mode(cmd, supported);
        ethtool_link_ksettings_add_link_mode(cmd, supported, 10baseT_Half);
        ethtool_link_ksettings_add_link_mode(cmd, supported, TP);

        ethtool_link_ksettings_zero_link_mode(cmd, advertising);
        ethtool_link_ksettings_add_link_mode(cmd, advertising, 10baseT_Half);
        ethtool_link_ksettings_add_link_mode(cmd, advertising, TP);

        cmd->base.speed = SPEED_10;
        cmd->base.duplex = DUPLEX_HALF;
        cmd->base.port = PORT_TP;
        cmd->base.phy_address = 0;
        cmd->base.autoneg = AUTONEG_DISABLE;

        return 0;
}

static const struct ethtool_ops sr9700_ethtool_ops = {
        .get_drvinfo    = usbnet_get_drvinfo,
        .get_link       = sr9700_get_link,
        .get_msglevel   = usbnet_get_msglevel,
        .set_msglevel   = usbnet_set_msglevel,
        .get_eeprom_len = sr9700_get_eeprom_len,
        .get_eeprom     = sr9700_get_eeprom,
        .get_link_ksettings     = sr9700_get_link_ksettings,
};

static void sr9700_set_multicast(struct net_device *netdev)
{
        struct usbnet *dev = netdev_priv(netdev);
        /* rx_ctl setting : enable, disable_long, disable_crc */
        u8 rx_ctl = RCR_RXEN | RCR_DIS_CRC | RCR_DIS_LONG;

        if (netdev->flags & IFF_PROMISC)
                rx_ctl |= RCR_PRMSC;
        else if (netdev->flags & IFF_ALLMULTI || !netdev_mc_empty(netdev))
                /* The chip has no multicast filter */
                rx_ctl |= RCR_ALL;

        sr_write_reg_async(dev, SR_RCR, rx_ctl);
}

static int sr9700_set_mac_address(struct net_device *netdev, void *p)
{
        struct usbnet *dev = netdev_priv(netdev);
        struct sockaddr *addr = p;

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

        eth_hw_addr_set(netdev, addr->sa_data);
        sr_write_async(dev, SR_PAR, ETH_ALEN, netdev->dev_addr);

        return 0;
}

static const struct net_device_ops sr9700_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_set_rx_mode        = sr9700_set_multicast,
        .ndo_set_mac_address    = sr9700_set_mac_address,
};

static int sr9700_bind(struct usbnet *dev, struct usb_interface *intf)
{
        struct net_device *netdev;
        u8 addr[ETH_ALEN];
        int ret;

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

        netdev = dev->net;

        netdev->netdev_ops = &sr9700_netdev_ops;
        netdev->ethtool_ops = &sr9700_ethtool_ops;
        netdev->hard_header_len += SR_TX_OVERHEAD;
        dev->hard_mtu = netdev->mtu + netdev->hard_header_len;
        /* bulkin buffer is preferably not less than 3K */
        dev->rx_urb_size = 3072;

        sr_write_reg(dev, SR_NCR, NCR_RST);
        udelay(20);

        /* read MAC
         * After Chip Power on, the Chip will reload the MAC from
         * EEPROM automatically to PAR. In case there is no EEPROM externally,
         * a default MAC address is stored in PAR for making chip work properly.
         */
        if (sr_read(dev, SR_PAR, ETH_ALEN, addr) < 0) {
                netdev_err(netdev, "Error reading MAC address\n");
                ret = -ENODEV;
                goto out;
        }
        eth_hw_addr_set(netdev, addr);

        /* power up and reset phy */
        sr_write_reg(dev, SR_PRR, PRR_PHY_RST);
        /* at least 10ms, here 20ms for safe */
        msleep(20);
        sr_write_reg(dev, SR_PRR, 0);
        /* at least 1ms, here 2ms for reading right register */
        udelay(2 * 1000);

        /* receive broadcast packets */
        sr9700_set_multicast(netdev);

out:
        return ret;
}

static int sr9700_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
        struct sk_buff *sr_skb;
        int len;

        /* skb content (packets) format :
         *                    p1            p2            p3    ......    pn
         *                 /      \
         *            /                \
         *        /                            \
         *  /                                        \
         * p1b1 p1b2 p1b3 p1b4 ...... p1b(n-4) p1b(n-3)...p1bn
         *
         * p1 : packet 1
         * p1b1 : packet 1 byte 1
         *
         * b1: rx status
         * b2: packet length (incl crc) low
         * b3: packet length (incl crc) high
         * b4..n-4: packet data
         * bn-3..bn: ethernet packet crc
         */
        if (unlikely(skb->len < SR_RX_OVERHEAD)) {
                netdev_err(dev->net, "unexpected tiny rx frame\n");
                return 0;
        }

        /* one skb may contains multiple packets */
        while (skb->len > SR_RX_OVERHEAD) {
                if (skb->data[0] != RSR_MF)
                        return 0;

                /* ignore the CRC length */
                len = (skb->data[1] | (skb->data[2] << 8)) - 4;

                if (len > ETH_FRAME_LEN || len > skb->len || len < 0)
                        return 0;

                /* the last packet of current skb */
                if (skb->len == (len + SR_RX_OVERHEAD)) {
                        skb_pull(skb, 3);
                        skb->len = len;
                        skb_set_tail_pointer(skb, len);
                        return 2;
                }

                sr_skb = netdev_alloc_skb_ip_align(dev->net, len);
                if (!sr_skb)
                        return 0;

                skb_put(sr_skb, len);
                memcpy(sr_skb->data, skb->data + 3, len);
                usbnet_skb_return(dev, sr_skb);

                skb_pull(skb, len + SR_RX_OVERHEAD);
        }

        return 0;
}

static struct sk_buff *sr9700_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
                                       gfp_t flags)
{
        int len;

        /* SR9700 can only send out one ethernet packet at once.
         *
         * b1 b2 b3 b4 ...... b(n-4) b(n-3)...bn
         *
         * b1: rx status
         * b2: packet length (incl crc) low
         * b3: packet length (incl crc) high
         * b4..n-4: packet data
         * bn-3..bn: ethernet packet crc
         */

        len = skb->len;

        if (skb_cow_head(skb, SR_TX_OVERHEAD)) {
                dev_kfree_skb_any(skb);
                return NULL;
        }

        __skb_push(skb, SR_TX_OVERHEAD);

        /* usbnet adds padding if length is a multiple of packet size
         * if so, adjust length value in header
         */
        if ((skb->len % dev->maxpacket) == 0)
                len++;

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

        return skb;
}

static void sr9700_status(struct usbnet *dev, struct urb *urb)
{
        bool link;
        u8 *buf;

        /* format:
           b1: net status
           b2: tx status 1
           b3: tx status 2
           b4: rx status
           b5: rx overflow
           b6: rx count
           b7: tx count
           b8: gpr
        */

        if (urb->actual_length < 8)
                return;

        buf = urb->transfer_buffer;

        link = !!(buf[0] & NSR_LINKST);
        sr9700_handle_link_change(dev->net, link);
}

static const struct driver_info sr9700_driver_info = {
        .description    = "CoreChip SR9700 USB Ethernet",
        .flags          = FLAG_ETHER,
        .bind           = sr9700_bind,
        .rx_fixup       = sr9700_rx_fixup,
        .tx_fixup       = sr9700_tx_fixup,
        .status         = sr9700_status,
};

static const struct usb_device_id products[] = {
        {
                USB_DEVICE(0x0fe6, 0x9700),     /* SR9700 device */
                .driver_info = (unsigned long)&sr9700_driver_info,
        },
        {
                /* SR9700 with virtual driver CD-ROM - interface 0 is the CD-ROM device */
                USB_DEVICE_INTERFACE_NUMBER(0x0fe6, 0x9702, 1),
                .driver_info = (unsigned long)&sr9700_driver_info,
        },
        {},                     /* END */
};

MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver sr9700_usb_driver = {
        .name           = "sr9700",
        .id_table       = products,
        .probe          = usbnet_probe,
        .disconnect     = usbnet_disconnect,
        .suspend        = usbnet_suspend,
        .resume         = usbnet_resume,
        .disable_hub_initiated_lpm = 1,
};

module_usb_driver(sr9700_usb_driver);

MODULE_AUTHOR("liujl <liujunliang_ljl@163.com>");
MODULE_DESCRIPTION("SR9700 one chip USB 1.1 USB to Ethernet device from http://www.corechip-sz.com/");
MODULE_LICENSE("GPL");