// SPDX-License-Identifier: GPL-2.0+
/*
 * Clean ups from Moschip version and a few ioctl implementations by:
 *      Paul B Schroeder <pschroeder "at" uplogix "dot" com>
 *
 * Originally based on drivers/usb/serial/io_edgeport.c which is:
 *      Copyright (C) 2000 Inside Out Networks, All rights reserved.
 *      Copyright (C) 2001-2002 Greg Kroah-Hartman <greg@kroah.com>
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>

#define DRIVER_DESC "Moschip 7840/7820 USB Serial Driver"

/*
 * 16C50 UART register defines
 */

#define LCR_BITS_5             0x00     /* 5 bits/char */
#define LCR_BITS_6             0x01     /* 6 bits/char */
#define LCR_BITS_7             0x02     /* 7 bits/char */
#define LCR_BITS_8             0x03     /* 8 bits/char */
#define LCR_BITS_MASK          0x03     /* Mask for bits/char field */

#define LCR_STOP_1             0x00     /* 1 stop bit */
#define LCR_STOP_1_5           0x04     /* 1.5 stop bits (if 5   bits/char) */
#define LCR_STOP_2             0x04     /* 2 stop bits   (if 6-8 bits/char) */
#define LCR_STOP_MASK          0x04     /* Mask for stop bits field */

#define LCR_PAR_NONE           0x00     /* No parity */
#define LCR_PAR_ODD            0x08     /* Odd parity */
#define LCR_PAR_EVEN           0x18     /* Even parity */
#define LCR_PAR_MARK           0x28     /* Force parity bit to 1 */
#define LCR_PAR_SPACE          0x38     /* Force parity bit to 0 */
#define LCR_PAR_MASK           0x38     /* Mask for parity field */

#define LCR_SET_BREAK          0x40     /* Set Break condition */
#define LCR_DL_ENABLE          0x80     /* Enable access to divisor latch */

#define MCR_DTR                0x01     /* Assert DTR */
#define MCR_RTS                0x02     /* Assert RTS */
#define MCR_OUT1               0x04     /* Loopback only: Sets state of RI */
#define MCR_MASTER_IE          0x08     /* Enable interrupt outputs */
#define MCR_LOOPBACK           0x10     /* Set internal (digital) loopback mode */
#define MCR_XON_ANY            0x20     /* Enable any char to exit XOFF mode */

#define MOS7840_MSR_CTS        0x10     /* Current state of CTS */
#define MOS7840_MSR_DSR        0x20     /* Current state of DSR */
#define MOS7840_MSR_RI         0x40     /* Current state of RI */
#define MOS7840_MSR_CD         0x80     /* Current state of CD */

/*
 * Defines used for sending commands to port
 */

#define MOS_WDR_TIMEOUT         5000    /* default urb timeout */

/* Requests */
#define MCS_RD_RTYPE    0xC0
#define MCS_WR_RTYPE    0x40
#define MCS_RDREQ       0x0D
#define MCS_WRREQ       0x0E
#define VENDOR_READ_LENGTH      (0x01)

#define ZLP_REG1  0x3A          /* Zero_Flag_Reg1    58 */
#define ZLP_REG5  0x3E          /* Zero_Flag_Reg5    62 */

/*
 * Vendor id and device id defines
 *
 * NOTE: Do not add new defines, add entries directly to the id_table instead.
 */
#define USB_VENDOR_ID_BANDB              0x0856
#define BANDB_DEVICE_ID_USO9ML2_2        0xAC22
#define BANDB_DEVICE_ID_USO9ML2_2P       0xBC00
#define BANDB_DEVICE_ID_USO9ML2_4        0xAC24
#define BANDB_DEVICE_ID_USO9ML2_4P       0xBC01
#define BANDB_DEVICE_ID_US9ML2_2         0xAC29
#define BANDB_DEVICE_ID_US9ML2_4         0xAC30
#define BANDB_DEVICE_ID_USPTL4_2         0xAC31
#define BANDB_DEVICE_ID_USPTL4_4         0xAC32
#define BANDB_DEVICE_ID_USOPTL4_2        0xAC42
#define BANDB_DEVICE_ID_USOPTL4_2P       0xBC02
#define BANDB_DEVICE_ID_USOPTL4_4        0xAC44
#define BANDB_DEVICE_ID_USOPTL4_4P       0xBC03

/* Interrupt Routine Defines    */

#define SERIAL_IIR_RLS      0x06
#define SERIAL_IIR_MS       0x00

/*
 *  Emulation of the bit mask on the LINE STATUS REGISTER.
 */
#define SERIAL_LSR_DR       0x0001
#define SERIAL_LSR_OE       0x0002
#define SERIAL_LSR_PE       0x0004
#define SERIAL_LSR_FE       0x0008
#define SERIAL_LSR_BI       0x0010

#define MOS_MSR_DELTA_CTS   0x10
#define MOS_MSR_DELTA_DSR   0x20
#define MOS_MSR_DELTA_RI    0x40
#define MOS_MSR_DELTA_CD    0x80

/* Serial Port register Address */
#define INTERRUPT_ENABLE_REGISTER  ((__u16)(0x01))
#define FIFO_CONTROL_REGISTER      ((__u16)(0x02))
#define LINE_CONTROL_REGISTER      ((__u16)(0x03))
#define MODEM_CONTROL_REGISTER     ((__u16)(0x04))
#define LINE_STATUS_REGISTER       ((__u16)(0x05))
#define MODEM_STATUS_REGISTER      ((__u16)(0x06))
#define SCRATCH_PAD_REGISTER       ((__u16)(0x07))
#define DIVISOR_LATCH_LSB          ((__u16)(0x00))
#define DIVISOR_LATCH_MSB          ((__u16)(0x01))

#define CLK_MULTI_REGISTER         ((__u16)(0x02))
#define CLK_START_VALUE_REGISTER   ((__u16)(0x03))
#define GPIO_REGISTER              ((__u16)(0x07))

#define SERIAL_LCR_DLAB            ((__u16)(0x0080))

/*
 * URB POOL related defines
 */
#define NUM_URBS                        16      /* URB Count */
#define URB_TRANSFER_BUFFER_SIZE        32      /* URB Size  */

/* LED on/off milliseconds*/
#define LED_ON_MS       500
#define LED_OFF_MS      500

enum mos7840_flag {
        MOS7840_FLAG_LED_BUSY,
};

#define MCS_PORT_MASK   GENMASK(2, 0)
#define MCS_PORTS(nr)   ((nr) & MCS_PORT_MASK)
#define MCS_LED         BIT(3)

#define MCS_DEVICE(vid, pid, flags) \
                USB_DEVICE((vid), (pid)), .driver_info = (flags)

static const struct usb_device_id id_table[] = {
        { MCS_DEVICE(0x0557, 0x2011, MCS_PORTS(4)) },   /* ATEN UC2324 */
        { MCS_DEVICE(0x0557, 0x7820, MCS_PORTS(2)) },   /* ATEN UC2322 */
        { MCS_DEVICE(0x110a, 0x2210, MCS_PORTS(2)) },   /* Moxa UPort 2210 */
        { MCS_DEVICE(0x9710, 0x7810, MCS_PORTS(1) | MCS_LED) }, /* ASIX MCS7810 */
        { MCS_DEVICE(0x9710, 0x7820, MCS_PORTS(2)) },   /* MosChip MCS7820 */
        { MCS_DEVICE(0x9710, 0x7840, MCS_PORTS(4)) },   /* MosChip MCS7840 */
        { MCS_DEVICE(0x9710, 0x7843, MCS_PORTS(3)) },   /* ASIX MCS7840 3 port */
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USO9ML2_2) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USO9ML2_2P) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USO9ML2_4) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USO9ML2_4P) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_US9ML2_2) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_US9ML2_4) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USPTL4_2) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USPTL4_4) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USOPTL4_2) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USOPTL4_2P) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USOPTL4_4) },
        { USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USOPTL4_4P) },
        {}                      /* terminating entry */
};
MODULE_DEVICE_TABLE(usb, id_table);

/* This structure holds all of the local port information */

struct moschip_port {
        int port_num;           /*Actual port number in the device(1,2,etc) */
        struct urb *read_urb;   /* read URB for this port */
        __u8 shadowLCR;         /* last LCR value received */
        __u8 shadowMCR;         /* last MCR value received */
        struct usb_serial_port *port;   /* loop back to the owner of this object */

        /* Offsets */
        __u8 SpRegOffset;
        __u8 ControlRegOffset;
        __u8 DcrRegOffset;

        spinlock_t pool_lock;
        struct urb *write_urb_pool[NUM_URBS];
        char busy[NUM_URBS];
        bool read_urb_busy;

        /* For device(s) with LED indicator */
        bool has_led;
        struct timer_list led_timer1;   /* Timer for LED on */
        struct timer_list led_timer2;   /* Timer for LED off */
        struct urb *led_urb;
        struct usb_ctrlrequest *led_dr;

        unsigned long flags;
};

/*
 * mos7840_set_reg_sync
 *      To set the Control register by calling usb_fill_control_urb function
 *      by passing usb_sndctrlpipe function as parameter.
 */

static int mos7840_set_reg_sync(struct usb_serial_port *port, __u16 reg,
                                __u16 val)
{
        struct usb_device *dev = port->serial->dev;
        val = val & 0x00ff;
        dev_dbg(&port->dev, "mos7840_set_reg_sync offset is %x, value %x\n", reg, val);

        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0), MCS_WRREQ,
                               MCS_WR_RTYPE, val, reg, NULL, 0,
                               MOS_WDR_TIMEOUT);
}

/*
 * mos7840_get_reg_sync
 *      To set the Uart register by calling usb_fill_control_urb function by
 *      passing usb_rcvctrlpipe function as parameter.
 */

static int mos7840_get_reg_sync(struct usb_serial_port *port, __u16 reg,
                                __u16 *val)
{
        struct usb_device *dev = port->serial->dev;
        int ret = 0;
        u8 *buf;

        buf = kmalloc(VENDOR_READ_LENGTH, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), MCS_RDREQ,
                              MCS_RD_RTYPE, 0, reg, buf, VENDOR_READ_LENGTH,
                              MOS_WDR_TIMEOUT);
        if (ret < VENDOR_READ_LENGTH) {
                if (ret >= 0)
                        ret = -EIO;
                goto out;
        }

        *val = buf[0];
        dev_dbg(&port->dev, "%s offset is %x, return val %x\n", __func__, reg, *val);
out:
        kfree(buf);
        return ret;
}

/*
 * mos7840_set_uart_reg
 *      To set the Uart register by calling usb_fill_control_urb function by
 *      passing usb_sndctrlpipe function as parameter.
 */

static int mos7840_set_uart_reg(struct usb_serial_port *port, __u16 reg,
                                __u16 val)
{

        struct usb_device *dev = port->serial->dev;
        val = val & 0x00ff;
        /* For the UART control registers, the application number need
           to be Or'ed */
        if (port->serial->num_ports == 2 && port->port_number != 0)
                val |= ((__u16)port->port_number + 2) << 8;
        else
                val |= ((__u16)port->port_number + 1) << 8;
        dev_dbg(&port->dev, "%s application number is %x\n", __func__, val);
        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0), MCS_WRREQ,
                               MCS_WR_RTYPE, val, reg, NULL, 0,
                               MOS_WDR_TIMEOUT);

}

/*
 * mos7840_get_uart_reg
 *      To set the Control register by calling usb_fill_control_urb function
 *      by passing usb_rcvctrlpipe function as parameter.
 */
static int mos7840_get_uart_reg(struct usb_serial_port *port, __u16 reg,
                                __u16 *val)
{
        struct usb_device *dev = port->serial->dev;
        int ret = 0;
        __u16 Wval;
        u8 *buf;

        buf = kmalloc(VENDOR_READ_LENGTH, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /* Wval  is same as application number */
        if (port->serial->num_ports == 2 && port->port_number != 0)
                Wval = ((__u16)port->port_number + 2) << 8;
        else
                Wval = ((__u16)port->port_number + 1) << 8;
        dev_dbg(&port->dev, "%s application number is %x\n", __func__, Wval);
        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), MCS_RDREQ,
                              MCS_RD_RTYPE, Wval, reg, buf, VENDOR_READ_LENGTH,
                              MOS_WDR_TIMEOUT);
        if (ret < VENDOR_READ_LENGTH) {
                if (ret >= 0)
                        ret = -EIO;
                goto out;
        }
        *val = buf[0];
out:
        kfree(buf);
        return ret;
}

static void mos7840_dump_serial_port(struct usb_serial_port *port,
                                     struct moschip_port *mos7840_port)
{

        dev_dbg(&port->dev, "SpRegOffset is %2x\n", mos7840_port->SpRegOffset);
        dev_dbg(&port->dev, "ControlRegOffset is %2x\n", mos7840_port->ControlRegOffset);
        dev_dbg(&port->dev, "DCRRegOffset is %2x\n", mos7840_port->DcrRegOffset);

}

/************************************************************************/
/************************************************************************/
/*            U S B  C A L L B A C K   F U N C T I O N S                */
/*            U S B  C A L L B A C K   F U N C T I O N S                */
/************************************************************************/
/************************************************************************/

static void mos7840_set_led_callback(struct urb *urb)
{
        switch (urb->status) {
        case 0:
                /* Success */
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                /* This urb is terminated, clean up */
                dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
                        __func__, urb->status);
                break;
        default:
                dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
                        __func__, urb->status);
        }
}

static void mos7840_set_led_async(struct moschip_port *mcs, __u16 wval,
                                __u16 reg)
{
        struct usb_device *dev = mcs->port->serial->dev;
        struct usb_ctrlrequest *dr = mcs->led_dr;

        dr->bRequestType = MCS_WR_RTYPE;
        dr->bRequest = MCS_WRREQ;
        dr->wValue = cpu_to_le16(wval);
        dr->wIndex = cpu_to_le16(reg);
        dr->wLength = cpu_to_le16(0);

        usb_fill_control_urb(mcs->led_urb, dev, usb_sndctrlpipe(dev, 0),
                (unsigned char *)dr, NULL, 0, mos7840_set_led_callback, NULL);

        usb_submit_urb(mcs->led_urb, GFP_ATOMIC);
}

static void mos7840_set_led_sync(struct usb_serial_port *port, __u16 reg,
                                __u16 val)
{
        struct usb_device *dev = port->serial->dev;

        usb_control_msg(dev, usb_sndctrlpipe(dev, 0), MCS_WRREQ, MCS_WR_RTYPE,
                        val, reg, NULL, 0, MOS_WDR_TIMEOUT);
}

static void mos7840_led_off(struct timer_list *t)
{
        struct moschip_port *mcs = timer_container_of(mcs, t, led_timer1);

        /* Turn off LED */
        mos7840_set_led_async(mcs, 0x0300, MODEM_CONTROL_REGISTER);
        mod_timer(&mcs->led_timer2,
                                jiffies + msecs_to_jiffies(LED_OFF_MS));
}

static void mos7840_led_flag_off(struct timer_list *t)
{
        struct moschip_port *mcs = timer_container_of(mcs, t, led_timer2);

        clear_bit_unlock(MOS7840_FLAG_LED_BUSY, &mcs->flags);
}

static void mos7840_led_activity(struct usb_serial_port *port)
{
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);

        if (test_and_set_bit_lock(MOS7840_FLAG_LED_BUSY, &mos7840_port->flags))
                return;

        mos7840_set_led_async(mos7840_port, 0x0301, MODEM_CONTROL_REGISTER);
        mod_timer(&mos7840_port->led_timer1,
                                jiffies + msecs_to_jiffies(LED_ON_MS));
}

/*****************************************************************************
 * mos7840_bulk_in_callback
 *      this is the callback function for when we have received data on the
 *      bulk in endpoint.
 *****************************************************************************/

static void mos7840_bulk_in_callback(struct urb *urb)
{
        struct moschip_port *mos7840_port = urb->context;
        struct usb_serial_port *port = mos7840_port->port;
        int retval;
        unsigned char *data;
        int status = urb->status;

        if (status) {
                dev_dbg(&urb->dev->dev, "nonzero read bulk status received: %d\n", status);
                mos7840_port->read_urb_busy = false;
                return;
        }

        data = urb->transfer_buffer;
        usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);

        if (urb->actual_length) {
                struct tty_port *tport = &mos7840_port->port->port;
                tty_insert_flip_string(tport, data, urb->actual_length);
                tty_flip_buffer_push(tport);
                port->icount.rx += urb->actual_length;
                dev_dbg(&port->dev, "icount.rx is %d:\n", port->icount.rx);
        }

        if (mos7840_port->has_led)
                mos7840_led_activity(port);

        mos7840_port->read_urb_busy = true;
        retval = usb_submit_urb(mos7840_port->read_urb, GFP_ATOMIC);

        if (retval) {
                dev_dbg(&port->dev, "usb_submit_urb(read bulk) failed, retval = %d\n", retval);
                mos7840_port->read_urb_busy = false;
        }
}

/*****************************************************************************
 * mos7840_bulk_out_data_callback
 *      this is the callback function for when we have finished sending
 *      serial data on the bulk out endpoint.
 *****************************************************************************/

static void mos7840_bulk_out_data_callback(struct urb *urb)
{
        struct moschip_port *mos7840_port = urb->context;
        struct usb_serial_port *port = mos7840_port->port;
        int status = urb->status;
        unsigned long flags;
        int i;

        spin_lock_irqsave(&mos7840_port->pool_lock, flags);
        for (i = 0; i < NUM_URBS; i++) {
                if (urb == mos7840_port->write_urb_pool[i]) {
                        mos7840_port->busy[i] = 0;
                        break;
                }
        }
        spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);

        if (status) {
                dev_dbg(&port->dev, "nonzero write bulk status received:%d\n", status);
                return;
        }

        tty_port_tty_wakeup(&port->port);

}

/************************************************************************/
/*       D R I V E R  T T Y  I N T E R F A C E  F U N C T I O N S       */
/************************************************************************/

/*****************************************************************************
 * mos7840_open
 *      this function is called by the tty driver when a port is opened
 *      If successful, we return 0
 *      Otherwise we return a negative error number.
 *****************************************************************************/

static int mos7840_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        int response;
        int j;
        struct urb *urb;
        __u16 Data;
        int status;

        usb_clear_halt(serial->dev, port->write_urb->pipe);
        usb_clear_halt(serial->dev, port->read_urb->pipe);

        /* Initialising the write urb pool */
        for (j = 0; j < NUM_URBS; ++j) {
                urb = usb_alloc_urb(0, GFP_KERNEL);
                mos7840_port->write_urb_pool[j] = urb;
                if (!urb)
                        continue;

                urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
                                                                GFP_KERNEL);
                if (!urb->transfer_buffer) {
                        usb_free_urb(urb);
                        mos7840_port->write_urb_pool[j] = NULL;
                        continue;
                }
        }

/*****************************************************************************
 * Initialize MCS7840 -- Write Init values to corresponding Registers
 *
 * Register Index
 * 1 : IER
 * 2 : FCR
 * 3 : LCR
 * 4 : MCR
 *
 * 0x08 : SP1/2 Control Reg
 *****************************************************************************/

        /* NEED to check the following Block */

        Data = 0x0;
        status = mos7840_get_reg_sync(port, mos7840_port->SpRegOffset, &Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Reading Spreg failed\n");
                goto err;
        }
        Data |= 0x80;
        status = mos7840_set_reg_sync(port, mos7840_port->SpRegOffset, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "writing Spreg failed\n");
                goto err;
        }

        Data &= ~0x80;
        status = mos7840_set_reg_sync(port, mos7840_port->SpRegOffset, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "writing Spreg failed\n");
                goto err;
        }
        /* End of block to be checked */

        Data = 0x0;
        status = mos7840_get_reg_sync(port, mos7840_port->ControlRegOffset,
                                                                        &Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Reading Controlreg failed\n");
                goto err;
        }
        Data |= 0x08;           /* Driver done bit */
        Data |= 0x20;           /* rx_disable */
        status = mos7840_set_reg_sync(port,
                                mos7840_port->ControlRegOffset, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "writing Controlreg failed\n");
                goto err;
        }
        /* do register settings here */
        /* Set all regs to the device default values. */
        /***********************************
         * First Disable all interrupts.
         ***********************************/
        Data = 0x00;
        status = mos7840_set_uart_reg(port, INTERRUPT_ENABLE_REGISTER, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "disabling interrupts failed\n");
                goto err;
        }
        /* Set FIFO_CONTROL_REGISTER to the default value */
        Data = 0x00;
        status = mos7840_set_uart_reg(port, FIFO_CONTROL_REGISTER, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing FIFO_CONTROL_REGISTER  failed\n");
                goto err;
        }

        Data = 0xcf;
        status = mos7840_set_uart_reg(port, FIFO_CONTROL_REGISTER, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing FIFO_CONTROL_REGISTER  failed\n");
                goto err;
        }

        Data = 0x03;
        status = mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);
        mos7840_port->shadowLCR = Data;

        Data = 0x0b;
        status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, Data);
        mos7840_port->shadowMCR = Data;

        Data = 0x00;
        status = mos7840_get_uart_reg(port, LINE_CONTROL_REGISTER, &Data);
        mos7840_port->shadowLCR = Data;

        Data |= SERIAL_LCR_DLAB;        /* data latch enable in LCR 0x80 */
        status = mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);

        Data = 0x0c;
        status = mos7840_set_uart_reg(port, DIVISOR_LATCH_LSB, Data);

        Data = 0x0;
        status = mos7840_set_uart_reg(port, DIVISOR_LATCH_MSB, Data);

        Data = 0x00;
        status = mos7840_get_uart_reg(port, LINE_CONTROL_REGISTER, &Data);

        Data = Data & ~SERIAL_LCR_DLAB;
        status = mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);
        mos7840_port->shadowLCR = Data;

        /* clearing Bulkin and Bulkout Fifo */
        Data = 0x0;
        status = mos7840_get_reg_sync(port, mos7840_port->SpRegOffset, &Data);

        Data = Data | 0x0c;
        status = mos7840_set_reg_sync(port, mos7840_port->SpRegOffset, Data);

        Data = Data & ~0x0c;
        status = mos7840_set_reg_sync(port, mos7840_port->SpRegOffset, Data);
        /* Finally enable all interrupts */
        Data = 0x0c;
        status = mos7840_set_uart_reg(port, INTERRUPT_ENABLE_REGISTER, Data);

        /* clearing rx_disable */
        Data = 0x0;
        status = mos7840_get_reg_sync(port, mos7840_port->ControlRegOffset,
                                                                        &Data);
        Data = Data & ~0x20;
        status = mos7840_set_reg_sync(port, mos7840_port->ControlRegOffset,
                                                                        Data);

        /* rx_negate */
        Data = 0x0;
        status = mos7840_get_reg_sync(port, mos7840_port->ControlRegOffset,
                                                                        &Data);
        Data = Data | 0x10;
        status = mos7840_set_reg_sync(port, mos7840_port->ControlRegOffset,
                                                                        Data);

        dev_dbg(&port->dev, "port number is %d\n", port->port_number);
        dev_dbg(&port->dev, "minor number is %d\n", port->minor);
        dev_dbg(&port->dev, "Bulkin endpoint is %d\n", port->bulk_in_endpointAddress);
        dev_dbg(&port->dev, "BulkOut endpoint is %d\n", port->bulk_out_endpointAddress);
        dev_dbg(&port->dev, "Interrupt endpoint is %d\n", port->interrupt_in_endpointAddress);
        dev_dbg(&port->dev, "port's number in the device is %d\n", mos7840_port->port_num);
        mos7840_port->read_urb = port->read_urb;

        /* set up our bulk in urb */
        if ((serial->num_ports == 2) && (((__u16)port->port_number % 2) != 0)) {
                usb_fill_bulk_urb(mos7840_port->read_urb,
                        serial->dev,
                        usb_rcvbulkpipe(serial->dev,
                                (port->bulk_in_endpointAddress) + 2),
                        port->bulk_in_buffer,
                        mos7840_port->read_urb->transfer_buffer_length,
                        mos7840_bulk_in_callback, mos7840_port);
        } else {
                usb_fill_bulk_urb(mos7840_port->read_urb,
                        serial->dev,
                        usb_rcvbulkpipe(serial->dev,
                                port->bulk_in_endpointAddress),
                        port->bulk_in_buffer,
                        mos7840_port->read_urb->transfer_buffer_length,
                        mos7840_bulk_in_callback, mos7840_port);
        }

        dev_dbg(&port->dev, "%s: bulkin endpoint is %d\n", __func__, port->bulk_in_endpointAddress);
        mos7840_port->read_urb_busy = true;
        response = usb_submit_urb(mos7840_port->read_urb, GFP_KERNEL);
        if (response) {
                dev_err(&port->dev, "%s - Error %d submitting control urb\n",
                        __func__, response);
                mos7840_port->read_urb_busy = false;
        }

        /* initialize our port settings */
        /* Must set to enable ints! */
        mos7840_port->shadowMCR = MCR_MASTER_IE;

        return 0;
err:
        for (j = 0; j < NUM_URBS; ++j) {
                urb = mos7840_port->write_urb_pool[j];
                if (!urb)
                        continue;
                kfree(urb->transfer_buffer);
                usb_free_urb(urb);
        }
        return status;
}

/*****************************************************************************
 * mos7840_chars_in_buffer
 *      this function is called by the tty driver when it wants to know how many
 *      bytes of data we currently have outstanding in the port (data that has
 *      been written, but hasn't made it out the port yet)
 *****************************************************************************/

static unsigned int mos7840_chars_in_buffer(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        int i;
        unsigned int chars = 0;
        unsigned long flags;

        spin_lock_irqsave(&mos7840_port->pool_lock, flags);
        for (i = 0; i < NUM_URBS; ++i) {
                if (mos7840_port->busy[i]) {
                        struct urb *urb = mos7840_port->write_urb_pool[i];
                        chars += urb->transfer_buffer_length;
                }
        }
        spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);
        dev_dbg(&port->dev, "%s - returns %u\n", __func__, chars);
        return chars;

}

/*****************************************************************************
 * mos7840_close
 *      this function is called by the tty driver when a port is closed
 *****************************************************************************/

static void mos7840_close(struct usb_serial_port *port)
{
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        int j;
        __u16 Data;

        for (j = 0; j < NUM_URBS; ++j)
                usb_kill_urb(mos7840_port->write_urb_pool[j]);

        /* Freeing Write URBs */
        for (j = 0; j < NUM_URBS; ++j) {
                if (mos7840_port->write_urb_pool[j]) {
                        kfree(mos7840_port->write_urb_pool[j]->transfer_buffer);
                        usb_free_urb(mos7840_port->write_urb_pool[j]);
                }
        }

        usb_kill_urb(mos7840_port->read_urb);
        mos7840_port->read_urb_busy = false;

        Data = 0x0;
        mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, Data);

        Data = 0x00;
        mos7840_set_uart_reg(port, INTERRUPT_ENABLE_REGISTER, Data);
}

/*****************************************************************************
 * mos7840_break
 *      this function sends a break to the port
 *****************************************************************************/
static int mos7840_break(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        unsigned char data;

        if (break_state == -1)
                data = mos7840_port->shadowLCR | LCR_SET_BREAK;
        else
                data = mos7840_port->shadowLCR & ~LCR_SET_BREAK;

        /* FIXME: no locking on shadowLCR anywhere in driver */
        mos7840_port->shadowLCR = data;
        dev_dbg(&port->dev, "%s mos7840_port->shadowLCR is %x\n", __func__, mos7840_port->shadowLCR);

        return mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER,
                                    mos7840_port->shadowLCR);
}

/*****************************************************************************
 * mos7840_write_room
 *      this function is called by the tty driver when it wants to know how many
 *      bytes of data we can accept for a specific port.
 *****************************************************************************/

static unsigned int mos7840_write_room(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        int i;
        unsigned int room = 0;
        unsigned long flags;

        spin_lock_irqsave(&mos7840_port->pool_lock, flags);
        for (i = 0; i < NUM_URBS; ++i) {
                if (!mos7840_port->busy[i])
                        room += URB_TRANSFER_BUFFER_SIZE;
        }
        spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);

        room = (room == 0) ? 0 : room - URB_TRANSFER_BUFFER_SIZE + 1;
        dev_dbg(&mos7840_port->port->dev, "%s - returns %u\n", __func__, room);
        return room;

}

/*****************************************************************************
 * mos7840_write
 *      this function is called by the tty driver when data should be written to
 *      the port.
 *      If successful, we return the number of bytes written, otherwise we
 *      return a negative error number.
 *****************************************************************************/

static int mos7840_write(struct tty_struct *tty, struct usb_serial_port *port,
                         const unsigned char *data, int count)
{
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        int status;
        int i;
        int bytes_sent = 0;
        int transfer_size;
        unsigned long flags;
        struct urb *urb;
        /* __u16 Data; */
        const unsigned char *current_position = data;

        /* try to find a free urb in the list */
        urb = NULL;

        spin_lock_irqsave(&mos7840_port->pool_lock, flags);
        for (i = 0; i < NUM_URBS; ++i) {
                if (!mos7840_port->busy[i]) {
                        mos7840_port->busy[i] = 1;
                        urb = mos7840_port->write_urb_pool[i];
                        dev_dbg(&port->dev, "URB:%d\n", i);
                        break;
                }
        }
        spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);

        if (urb == NULL) {
                dev_dbg(&port->dev, "%s - no more free urbs\n", __func__);
                goto exit;
        }

        if (urb->transfer_buffer == NULL) {
                urb->transfer_buffer = kmalloc(URB_TRANSFER_BUFFER_SIZE,
                                               GFP_ATOMIC);
                if (!urb->transfer_buffer) {
                        bytes_sent = -ENOMEM;
                        goto exit;
                }
        }
        transfer_size = min(count, URB_TRANSFER_BUFFER_SIZE);

        memcpy(urb->transfer_buffer, current_position, transfer_size);

        /* fill urb with data and submit  */
        if ((serial->num_ports == 2) && (((__u16)port->port_number % 2) != 0)) {
                usb_fill_bulk_urb(urb,
                        serial->dev,
                        usb_sndbulkpipe(serial->dev,
                                (port->bulk_out_endpointAddress) + 2),
                        urb->transfer_buffer,
                        transfer_size,
                        mos7840_bulk_out_data_callback, mos7840_port);
        } else {
                usb_fill_bulk_urb(urb,
                        serial->dev,
                        usb_sndbulkpipe(serial->dev,
                                port->bulk_out_endpointAddress),
                        urb->transfer_buffer,
                        transfer_size,
                        mos7840_bulk_out_data_callback, mos7840_port);
        }

        dev_dbg(&port->dev, "bulkout endpoint is %d\n", port->bulk_out_endpointAddress);

        if (mos7840_port->has_led)
                mos7840_led_activity(port);

        /* send it down the pipe */
        status = usb_submit_urb(urb, GFP_ATOMIC);

        if (status) {
                mos7840_port->busy[i] = 0;
                dev_err_console(port, "%s - usb_submit_urb(write bulk) failed "
                        "with status = %d\n", __func__, status);
                bytes_sent = status;
                goto exit;
        }
        bytes_sent = transfer_size;
        port->icount.tx += transfer_size;
        dev_dbg(&port->dev, "icount.tx is %d:\n", port->icount.tx);
exit:
        return bytes_sent;

}

/*****************************************************************************
 * mos7840_throttle
 *      this function is called by the tty driver when it wants to stop the data
 *      being read from the port.
 *****************************************************************************/

static void mos7840_throttle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        int status;

        /* if we are implementing XON/XOFF, send the stop character */
        if (I_IXOFF(tty)) {
                unsigned char stop_char = STOP_CHAR(tty);
                status = mos7840_write(tty, port, &stop_char, 1);
                if (status <= 0)
                        return;
        }
        /* if we are implementing RTS/CTS, toggle that line */
        if (C_CRTSCTS(tty)) {
                mos7840_port->shadowMCR &= ~MCR_RTS;
                status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER,
                                         mos7840_port->shadowMCR);
                if (status < 0)
                        return;
        }
}

/*****************************************************************************
 * mos7840_unthrottle
 *      this function is called by the tty driver when it wants to resume
 *      the data being read from the port (called after mos7840_throttle is
 *      called)
 *****************************************************************************/
static void mos7840_unthrottle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        int status;

        /* if we are implementing XON/XOFF, send the start character */
        if (I_IXOFF(tty)) {
                unsigned char start_char = START_CHAR(tty);
                status = mos7840_write(tty, port, &start_char, 1);
                if (status <= 0)
                        return;
        }

        /* if we are implementing RTS/CTS, toggle that line */
        if (C_CRTSCTS(tty)) {
                mos7840_port->shadowMCR |= MCR_RTS;
                status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER,
                                         mos7840_port->shadowMCR);
                if (status < 0)
                        return;
        }
}

static int mos7840_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        unsigned int result;
        __u16 msr;
        __u16 mcr;
        int status;

        status = mos7840_get_uart_reg(port, MODEM_STATUS_REGISTER, &msr);
        if (status < 0)
                return -EIO;
        status = mos7840_get_uart_reg(port, MODEM_CONTROL_REGISTER, &mcr);
        if (status < 0)
                return -EIO;
        result = ((mcr & MCR_DTR) ? TIOCM_DTR : 0)
            | ((mcr & MCR_RTS) ? TIOCM_RTS : 0)
            | ((mcr & MCR_LOOPBACK) ? TIOCM_LOOP : 0)
            | ((msr & MOS7840_MSR_CTS) ? TIOCM_CTS : 0)
            | ((msr & MOS7840_MSR_CD) ? TIOCM_CAR : 0)
            | ((msr & MOS7840_MSR_RI) ? TIOCM_RI : 0)
            | ((msr & MOS7840_MSR_DSR) ? TIOCM_DSR : 0);

        dev_dbg(&port->dev, "%s - 0x%04X\n", __func__, result);

        return result;
}

static int mos7840_tiocmset(struct tty_struct *tty,
                            unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        unsigned int mcr;
        int status;

        /* FIXME: What locks the port registers ? */
        mcr = mos7840_port->shadowMCR;
        if (clear & TIOCM_RTS)
                mcr &= ~MCR_RTS;
        if (clear & TIOCM_DTR)
                mcr &= ~MCR_DTR;
        if (clear & TIOCM_LOOP)
                mcr &= ~MCR_LOOPBACK;

        if (set & TIOCM_RTS)
                mcr |= MCR_RTS;
        if (set & TIOCM_DTR)
                mcr |= MCR_DTR;
        if (set & TIOCM_LOOP)
                mcr |= MCR_LOOPBACK;

        mos7840_port->shadowMCR = mcr;

        status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, mcr);
        if (status < 0) {
                dev_dbg(&port->dev, "setting MODEM_CONTROL_REGISTER Failed\n");
                return status;
        }

        return 0;
}

/*****************************************************************************
 * mos7840_calc_baud_rate_divisor
 *      this function calculates the proper baud rate divisor for the specified
 *      baud rate.
 *****************************************************************************/
static int mos7840_calc_baud_rate_divisor(struct usb_serial_port *port,
                                          int baudRate, int *divisor,
                                          __u16 *clk_sel_val)
{
        dev_dbg(&port->dev, "%s - %d\n", __func__, baudRate);

        if (baudRate <= 115200) {
                *divisor = 115200 / baudRate;
                *clk_sel_val = 0x0;
        }
        if ((baudRate > 115200) && (baudRate <= 230400)) {
                *divisor = 230400 / baudRate;
                *clk_sel_val = 0x10;
        } else if ((baudRate > 230400) && (baudRate <= 403200)) {
                *divisor = 403200 / baudRate;
                *clk_sel_val = 0x20;
        } else if ((baudRate > 403200) && (baudRate <= 460800)) {
                *divisor = 460800 / baudRate;
                *clk_sel_val = 0x30;
        } else if ((baudRate > 460800) && (baudRate <= 806400)) {
                *divisor = 806400 / baudRate;
                *clk_sel_val = 0x40;
        } else if ((baudRate > 806400) && (baudRate <= 921600)) {
                *divisor = 921600 / baudRate;
                *clk_sel_val = 0x50;
        } else if ((baudRate > 921600) && (baudRate <= 1572864)) {
                *divisor = 1572864 / baudRate;
                *clk_sel_val = 0x60;
        } else if ((baudRate > 1572864) && (baudRate <= 3145728)) {
                *divisor = 3145728 / baudRate;
                *clk_sel_val = 0x70;
        }
        return 0;
}

/*****************************************************************************
 * mos7840_send_cmd_write_baud_rate
 *      this function sends the proper command to change the baud rate of the
 *      specified port.
 *****************************************************************************/

static int mos7840_send_cmd_write_baud_rate(struct moschip_port *mos7840_port,
                                            int baudRate)
{
        struct usb_serial_port *port = mos7840_port->port;
        int divisor = 0;
        int status;
        __u16 Data;
        __u16 clk_sel_val;

        dev_dbg(&port->dev, "%s - baud = %d\n", __func__, baudRate);
        /* reset clk_uart_sel in spregOffset */
        if (baudRate > 115200) {
#ifdef HW_flow_control
                /* NOTE: need to see the pther register to modify */
                /* setting h/w flow control bit to 1 */
                Data = 0x2b;
                mos7840_port->shadowMCR = Data;
                status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER,
                                                                        Data);
                if (status < 0) {
                        dev_dbg(&port->dev, "Writing spreg failed in set_serial_baud\n");
                        return -1;
                }
#endif

        } else {
#ifdef HW_flow_control
                /* setting h/w flow control bit to 0 */
                Data = 0xb;
                mos7840_port->shadowMCR = Data;
                status = mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER,
                                                                        Data);
                if (status < 0) {
                        dev_dbg(&port->dev, "Writing spreg failed in set_serial_baud\n");
                        return -1;
                }
#endif

        }

        if (1) {                /* baudRate <= 115200) */
                clk_sel_val = 0x0;
                Data = 0x0;
                status = mos7840_calc_baud_rate_divisor(port, baudRate, &divisor,
                                                   &clk_sel_val);
                status = mos7840_get_reg_sync(port, mos7840_port->SpRegOffset,
                                                                 &Data);
                if (status < 0) {
                        dev_dbg(&port->dev, "reading spreg failed in set_serial_baud\n");
                        return -1;
                }
                Data = (Data & 0x8f) | clk_sel_val;
                status = mos7840_set_reg_sync(port, mos7840_port->SpRegOffset,
                                                                Data);
                if (status < 0) {
                        dev_dbg(&port->dev, "Writing spreg failed in set_serial_baud\n");
                        return -1;
                }
                /* Calculate the Divisor */

                if (status) {
                        dev_err(&port->dev, "%s - bad baud rate\n", __func__);
                        return status;
                }
                /* Enable access to divisor latch */
                Data = mos7840_port->shadowLCR | SERIAL_LCR_DLAB;
                mos7840_port->shadowLCR = Data;
                mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);

                /* Write the divisor */
                Data = (unsigned char)(divisor & 0xff);
                dev_dbg(&port->dev, "set_serial_baud Value to write DLL is %x\n", Data);
                mos7840_set_uart_reg(port, DIVISOR_LATCH_LSB, Data);

                Data = (unsigned char)((divisor & 0xff00) >> 8);
                dev_dbg(&port->dev, "set_serial_baud Value to write DLM is %x\n", Data);
                mos7840_set_uart_reg(port, DIVISOR_LATCH_MSB, Data);

                /* Disable access to divisor latch */
                Data = mos7840_port->shadowLCR & ~SERIAL_LCR_DLAB;
                mos7840_port->shadowLCR = Data;
                mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);

        }
        return status;
}

/*****************************************************************************
 * mos7840_change_port_settings
 *      This routine is called to set the UART on the device to match
 *      the specified new settings.
 *****************************************************************************/

static void mos7840_change_port_settings(struct tty_struct *tty,
                                         struct moschip_port *mos7840_port,
                                         const struct ktermios *old_termios)
{
        struct usb_serial_port *port = mos7840_port->port;
        int baud;
        unsigned cflag;
        __u8 lData;
        __u8 lParity;
        __u8 lStop;
        int status;
        __u16 Data;

        lData = LCR_BITS_8;
        lStop = LCR_STOP_1;
        lParity = LCR_PAR_NONE;

        cflag = tty->termios.c_cflag;

        /* Change the number of bits */
        switch (cflag & CSIZE) {
        case CS5:
                lData = LCR_BITS_5;
                break;

        case CS6:
                lData = LCR_BITS_6;
                break;

        case CS7:
                lData = LCR_BITS_7;
                break;

        default:
        case CS8:
                lData = LCR_BITS_8;
                break;
        }

        /* Change the Parity bit */
        if (cflag & PARENB) {
                if (cflag & PARODD) {
                        lParity = LCR_PAR_ODD;
                        dev_dbg(&port->dev, "%s - parity = odd\n", __func__);
                } else {
                        lParity = LCR_PAR_EVEN;
                        dev_dbg(&port->dev, "%s - parity = even\n", __func__);
                }

        } else {
                dev_dbg(&port->dev, "%s - parity = none\n", __func__);
        }

        if (cflag & CMSPAR)
                lParity = lParity | 0x20;

        /* Change the Stop bit */
        if (cflag & CSTOPB) {
                lStop = LCR_STOP_2;
                dev_dbg(&port->dev, "%s - stop bits = 2\n", __func__);
        } else {
                lStop = LCR_STOP_1;
                dev_dbg(&port->dev, "%s - stop bits = 1\n", __func__);
        }

        /* Update the LCR with the correct value */
        mos7840_port->shadowLCR &=
            ~(LCR_BITS_MASK | LCR_STOP_MASK | LCR_PAR_MASK);
        mos7840_port->shadowLCR |= (lData | lParity | lStop);

        dev_dbg(&port->dev, "%s - mos7840_port->shadowLCR is %x\n", __func__,
                mos7840_port->shadowLCR);
        /* Disable Interrupts */
        Data = 0x00;
        mos7840_set_uart_reg(port, INTERRUPT_ENABLE_REGISTER, Data);

        Data = 0x00;
        mos7840_set_uart_reg(port, FIFO_CONTROL_REGISTER, Data);

        Data = 0xcf;
        mos7840_set_uart_reg(port, FIFO_CONTROL_REGISTER, Data);

        /* Send the updated LCR value to the mos7840 */
        Data = mos7840_port->shadowLCR;

        mos7840_set_uart_reg(port, LINE_CONTROL_REGISTER, Data);

        Data = 0x00b;
        mos7840_port->shadowMCR = Data;
        mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, Data);
        Data = 0x00b;
        mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, Data);

        /* set up the MCR register and send it to the mos7840 */

        mos7840_port->shadowMCR = MCR_MASTER_IE;
        if (cflag & CBAUD)
                mos7840_port->shadowMCR |= (MCR_DTR | MCR_RTS);

        if (cflag & CRTSCTS)
                mos7840_port->shadowMCR |= (MCR_XON_ANY);
        else
                mos7840_port->shadowMCR &= ~(MCR_XON_ANY);

        Data = mos7840_port->shadowMCR;
        mos7840_set_uart_reg(port, MODEM_CONTROL_REGISTER, Data);

        /* Determine divisor based on baud rate */
        baud = tty_get_baud_rate(tty);

        if (!baud) {
                /* pick a default, any default... */
                dev_dbg(&port->dev, "%s", "Picked default baud...\n");
                baud = 9600;
        }

        dev_dbg(&port->dev, "%s - baud rate = %d\n", __func__, baud);
        status = mos7840_send_cmd_write_baud_rate(mos7840_port, baud);

        /* Enable Interrupts */
        Data = 0x0c;
        mos7840_set_uart_reg(port, INTERRUPT_ENABLE_REGISTER, Data);

        if (!mos7840_port->read_urb_busy) {
                mos7840_port->read_urb_busy = true;
                status = usb_submit_urb(mos7840_port->read_urb, GFP_KERNEL);
                if (status) {
                        dev_dbg(&port->dev, "usb_submit_urb(read bulk) failed, status = %d\n",
                            status);
                        mos7840_port->read_urb_busy = false;
                }
        }
        dev_dbg(&port->dev, "%s - mos7840_port->shadowLCR is End %x\n", __func__,
                mos7840_port->shadowLCR);
}

/*****************************************************************************
 * mos7840_set_termios
 *      this function is called by the tty driver when it wants to change
 *      the termios structure
 *****************************************************************************/

static void mos7840_set_termios(struct tty_struct *tty,
                                struct usb_serial_port *port,
                                const struct ktermios *old_termios)
{
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);
        int status;

        /* change the port settings to the new ones specified */

        mos7840_change_port_settings(tty, mos7840_port, old_termios);

        if (!mos7840_port->read_urb_busy) {
                mos7840_port->read_urb_busy = true;
                status = usb_submit_urb(mos7840_port->read_urb, GFP_KERNEL);
                if (status) {
                        dev_dbg(&port->dev, "usb_submit_urb(read bulk) failed, status = %d\n",
                            status);
                        mos7840_port->read_urb_busy = false;
                }
        }
}

/*****************************************************************************
 * mos7840_get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *          is emptied.  On bus types like RS485, the transmitter must
 *          release the bus after transmitting. This must be done when
 *          the transmit shift register is empty, not be done when the
 *          transmit holding register is empty.  This functionality
 *          allows an RS485 driver to be written in user space.
 *****************************************************************************/

static int mos7840_get_lsr_info(struct tty_struct *tty,
                                unsigned int __user *value)
{
        int count;
        unsigned int result = 0;

        count = mos7840_chars_in_buffer(tty);
        if (count == 0)
                result = TIOCSER_TEMT;

        if (copy_to_user(value, &result, sizeof(int)))
                return -EFAULT;
        return 0;
}

/*****************************************************************************
 * SerialIoctl
 *      this function handles any ioctl calls to the driver
 *****************************************************************************/

static int mos7840_ioctl(struct tty_struct *tty,
                         unsigned int cmd, unsigned long arg)
{
        struct usb_serial_port *port = tty->driver_data;
        void __user *argp = (void __user *)arg;

        switch (cmd) {
                /* return number of bytes available */

        case TIOCSERGETLSR:
                dev_dbg(&port->dev, "%s TIOCSERGETLSR\n", __func__);
                return mos7840_get_lsr_info(tty, argp);

        default:
                break;
        }
        return -ENOIOCTLCMD;
}

/*
 * Check if GPO (pin 42) is connected to GPI (pin 33) as recommended by ASIX
 * for MCS7810 by bit-banging a 16-bit word.
 *
 * Note that GPO is really RTS of the third port so this will toggle RTS of
 * port two or three on two- and four-port devices.
 */
static int mos7810_check(struct usb_serial *serial)
{
        int i, pass_count = 0;
        u8 *buf;
        __u16 data = 0, mcr_data = 0;
        __u16 test_pattern = 0x55AA;
        int res;

        buf = kmalloc(VENDOR_READ_LENGTH, GFP_KERNEL);
        if (!buf)
                return 0;       /* failed to identify 7810 */

        /* Store MCR setting */
        res = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
                MCS_RDREQ, MCS_RD_RTYPE, 0x0300, MODEM_CONTROL_REGISTER,
                buf, VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
        if (res == VENDOR_READ_LENGTH)
                mcr_data = *buf;

        for (i = 0; i < 16; i++) {
                /* Send the 1-bit test pattern out to MCS7810 test pin */
                usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                        MCS_WRREQ, MCS_WR_RTYPE,
                        (0x0300 | (((test_pattern >> i) & 0x0001) << 1)),
                        MODEM_CONTROL_REGISTER, NULL, 0, MOS_WDR_TIMEOUT);

                /* Read the test pattern back */
                res = usb_control_msg(serial->dev,
                                usb_rcvctrlpipe(serial->dev, 0), MCS_RDREQ,
                                MCS_RD_RTYPE, 0, GPIO_REGISTER, buf,
                                VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);
                if (res == VENDOR_READ_LENGTH)
                        data = *buf;

                /* If this is a MCS7810 device, both test patterns must match */
                if (((test_pattern >> i) ^ (~data >> 1)) & 0x0001)
                        break;

                pass_count++;
        }

        /* Restore MCR setting */
        usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), MCS_WRREQ,
                MCS_WR_RTYPE, 0x0300 | mcr_data, MODEM_CONTROL_REGISTER, NULL,
                0, MOS_WDR_TIMEOUT);

        kfree(buf);

        if (pass_count == 16)
                return 1;

        return 0;
}

static int mos7840_probe(struct usb_serial *serial,
                                const struct usb_device_id *id)
{
        unsigned long device_flags = id->driver_info;
        u8 *buf;

        /* Skip device-type detection if we already have device flags. */
        if (device_flags)
                goto out;

        buf = kzalloc(VENDOR_READ_LENGTH, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
                        MCS_RDREQ, MCS_RD_RTYPE, 0, GPIO_REGISTER, buf,
                        VENDOR_READ_LENGTH, MOS_WDR_TIMEOUT);

        /* For a MCS7840 device GPIO0 must be set to 1 */
        if (buf[0] & 0x01)
                device_flags = MCS_PORTS(4);
        else if (mos7810_check(serial))
                device_flags = MCS_PORTS(1) | MCS_LED;
        else
                device_flags = MCS_PORTS(2);

        kfree(buf);
out:
        usb_set_serial_data(serial, (void *)device_flags);

        return 0;
}

static int mos7840_calc_num_ports(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds)
{
        unsigned long device_flags = (unsigned long)usb_get_serial_data(serial);
        int num_ports = MCS_PORTS(device_flags);

        if (num_ports == 0 || num_ports > 4)
                return -ENODEV;

        if (epds->num_bulk_in < num_ports || epds->num_bulk_out < num_ports) {
                dev_err(&serial->interface->dev, "missing endpoints\n");
                return -ENODEV;
        }

        return num_ports;
}

static int mos7840_attach(struct usb_serial *serial)
{
        struct device *dev = &serial->interface->dev;
        int status;
        u16 val;

        /* Zero Length flag enable */
        val = 0x0f;
        status = mos7840_set_reg_sync(serial->port[0], ZLP_REG5, val);
        if (status < 0)
                dev_dbg(dev, "Writing ZLP_REG5 failed status-0x%x\n", status);
        else
                dev_dbg(dev, "ZLP_REG5 Writing success status%d\n", status);

        return status;
}

static int mos7840_port_probe(struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;
        unsigned long device_flags = (unsigned long)usb_get_serial_data(serial);
        struct moschip_port *mos7840_port;
        int status;
        int pnum;
        __u16 Data;

        /* we set up the pointers to the endpoints in the mos7840_open *
         * function, as the structures aren't created yet.             */

        pnum = port->port_number;

        dev_dbg(&port->dev, "mos7840_startup: configuring port %d\n", pnum);
        mos7840_port = kzalloc_obj(struct moschip_port);
        if (!mos7840_port)
                return -ENOMEM;

        /* Initialize all port interrupt end point to port 0 int
         * endpoint. Our device has only one interrupt end point
         * common to all port */

        mos7840_port->port = port;
        spin_lock_init(&mos7840_port->pool_lock);

        /* minor is not initialised until later by
         * usb-serial.c:get_free_serial() and cannot therefore be used
         * to index device instances */
        mos7840_port->port_num = pnum + 1;
        dev_dbg(&port->dev, "port->minor = %d\n", port->minor);
        dev_dbg(&port->dev, "mos7840_port->port_num = %d\n", mos7840_port->port_num);

        if (mos7840_port->port_num == 1) {
                mos7840_port->SpRegOffset = 0x0;
                mos7840_port->ControlRegOffset = 0x1;
                mos7840_port->DcrRegOffset = 0x4;
        } else {
                u8 phy_num = mos7840_port->port_num;

                /* Port 2 in the 2-port case uses registers of port 3 */
                if (serial->num_ports == 2)
                        phy_num = 3;

                mos7840_port->SpRegOffset = 0x8 + 2 * (phy_num - 2);
                mos7840_port->ControlRegOffset = 0x9 + 2 * (phy_num - 2);
                mos7840_port->DcrRegOffset = 0x16 + 3 * (phy_num - 2);
        }
        mos7840_dump_serial_port(port, mos7840_port);
        usb_set_serial_port_data(port, mos7840_port);

        /* enable rx_disable bit in control register */
        status = mos7840_get_reg_sync(port,
                        mos7840_port->ControlRegOffset, &Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Reading ControlReg failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "ControlReg Reading success val is %x, status%d\n", Data, status);
        Data |= 0x08;   /* setting driver done bit */
        Data |= 0x04;   /* sp1_bit to have cts change reflect in
                           modem status reg */

        /* Data |= 0x20; //rx_disable bit */
        status = mos7840_set_reg_sync(port,
                        mos7840_port->ControlRegOffset, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing ControlReg failed(rx_disable) status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "ControlReg Writing success(rx_disable) status%d\n", status);

        /* Write default values in DCR (i.e 0x01 in DCR0, 0x05 in DCR2
           and 0x24 in DCR3 */
        Data = 0x01;
        status = mos7840_set_reg_sync(port,
                        (__u16) (mos7840_port->DcrRegOffset + 0), Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing DCR0 failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "DCR0 Writing success status%d\n", status);

        Data = 0x05;
        status = mos7840_set_reg_sync(port,
                        (__u16) (mos7840_port->DcrRegOffset + 1), Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing DCR1 failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "DCR1 Writing success status%d\n", status);

        Data = 0x24;
        status = mos7840_set_reg_sync(port,
                        (__u16) (mos7840_port->DcrRegOffset + 2), Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing DCR2 failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "DCR2 Writing success status%d\n", status);

        /* write values in clkstart0x0 and clkmulti 0x20 */
        Data = 0x0;
        status = mos7840_set_reg_sync(port, CLK_START_VALUE_REGISTER, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing CLK_START_VALUE_REGISTER failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "CLK_START_VALUE_REGISTER Writing success status%d\n", status);

        Data = 0x20;
        status = mos7840_set_reg_sync(port, CLK_MULTI_REGISTER, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing CLK_MULTI_REGISTER failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "CLK_MULTI_REGISTER Writing success status%d\n", status);

        /* write value 0x0 to scratchpad register */
        Data = 0x00;
        status = mos7840_set_uart_reg(port, SCRATCH_PAD_REGISTER, Data);
        if (status < 0) {
                dev_dbg(&port->dev, "Writing SCRATCH_PAD_REGISTER failed status-0x%x\n", status);
                goto error;
        } else
                dev_dbg(&port->dev, "SCRATCH_PAD_REGISTER Writing success status%d\n", status);

        /* Zero Length flag register */
        if ((mos7840_port->port_num != 1) && (serial->num_ports == 2)) {
                Data = 0xff;
                status = mos7840_set_reg_sync(port,
                                (__u16) (ZLP_REG1 +
                                        ((__u16)mos7840_port->port_num)), Data);
                dev_dbg(&port->dev, "ZLIP offset %x\n",
                                (__u16)(ZLP_REG1 + ((__u16) mos7840_port->port_num)));
                if (status < 0) {
                        dev_dbg(&port->dev, "Writing ZLP_REG%d failed status-0x%x\n", pnum + 2, status);
                        goto error;
                } else
                        dev_dbg(&port->dev, "ZLP_REG%d Writing success status%d\n", pnum + 2, status);
        } else {
                Data = 0xff;
                status = mos7840_set_reg_sync(port,
                                (__u16) (ZLP_REG1 +
                                        ((__u16)mos7840_port->port_num) - 0x1), Data);
                dev_dbg(&port->dev, "ZLIP offset %x\n",
                                (__u16)(ZLP_REG1 + ((__u16) mos7840_port->port_num) - 0x1));
                if (status < 0) {
                        dev_dbg(&port->dev, "Writing ZLP_REG%d failed status-0x%x\n", pnum + 1, status);
                        goto error;
                } else
                        dev_dbg(&port->dev, "ZLP_REG%d Writing success status%d\n", pnum + 1, status);

        }

        mos7840_port->has_led = device_flags & MCS_LED;

        /* Initialize LED timers */
        if (mos7840_port->has_led) {
                mos7840_port->led_urb = usb_alloc_urb(0, GFP_KERNEL);
                mos7840_port->led_dr = kmalloc_obj(*mos7840_port->led_dr);
                if (!mos7840_port->led_urb || !mos7840_port->led_dr) {
                        status = -ENOMEM;
                        goto error;
                }

                timer_setup(&mos7840_port->led_timer1, mos7840_led_off, 0);
                mos7840_port->led_timer1.expires =
                        jiffies + msecs_to_jiffies(LED_ON_MS);
                timer_setup(&mos7840_port->led_timer2, mos7840_led_flag_off,
                            0);
                mos7840_port->led_timer2.expires =
                        jiffies + msecs_to_jiffies(LED_OFF_MS);

                /* Turn off LED */
                mos7840_set_led_sync(port, MODEM_CONTROL_REGISTER, 0x0300);
        }

        return 0;
error:
        kfree(mos7840_port->led_dr);
        usb_free_urb(mos7840_port->led_urb);
        kfree(mos7840_port);

        return status;
}

static void mos7840_port_remove(struct usb_serial_port *port)
{
        struct moschip_port *mos7840_port = usb_get_serial_port_data(port);

        if (mos7840_port->has_led) {
                /* Turn off LED */
                mos7840_set_led_sync(port, MODEM_CONTROL_REGISTER, 0x0300);

                timer_shutdown_sync(&mos7840_port->led_timer1);
                timer_shutdown_sync(&mos7840_port->led_timer2);

                usb_kill_urb(mos7840_port->led_urb);
                usb_free_urb(mos7840_port->led_urb);
                kfree(mos7840_port->led_dr);
        }

        kfree(mos7840_port);
}

static int mos7840_suspend(struct usb_serial *serial, pm_message_t message)
{
        struct moschip_port *mos7840_port;
        struct usb_serial_port *port;
        int i;

        for (i = 0; i < serial->num_ports; ++i) {
                port = serial->port[i];
                if (!tty_port_initialized(&port->port))
                        continue;

                mos7840_port = usb_get_serial_port_data(port);

                usb_kill_urb(mos7840_port->read_urb);
                mos7840_port->read_urb_busy = false;
        }

        return 0;
}

static int mos7840_resume(struct usb_serial *serial)
{
        struct moschip_port *mos7840_port;
        struct usb_serial_port *port;
        int res;
        int i;

        for (i = 0; i < serial->num_ports; ++i) {
                port = serial->port[i];
                if (!tty_port_initialized(&port->port))
                        continue;

                mos7840_port = usb_get_serial_port_data(port);

                mos7840_port->read_urb_busy = true;
                res = usb_submit_urb(mos7840_port->read_urb, GFP_NOIO);
                if (res)
                        mos7840_port->read_urb_busy = false;
        }

        return 0;
}

static struct usb_serial_driver moschip7840_4port_device = {
        .driver = {
                   .name = "mos7840",
                   },
        .description = DRIVER_DESC,
        .id_table = id_table,
        .num_interrupt_in = 1,
        .open = mos7840_open,
        .close = mos7840_close,
        .write = mos7840_write,
        .write_room = mos7840_write_room,
        .chars_in_buffer = mos7840_chars_in_buffer,
        .throttle = mos7840_throttle,
        .unthrottle = mos7840_unthrottle,
        .calc_num_ports = mos7840_calc_num_ports,
        .probe = mos7840_probe,
        .attach = mos7840_attach,
        .ioctl = mos7840_ioctl,
        .set_termios = mos7840_set_termios,
        .break_ctl = mos7840_break,
        .tiocmget = mos7840_tiocmget,
        .tiocmset = mos7840_tiocmset,
        .get_icount = usb_serial_generic_get_icount,
        .port_probe = mos7840_port_probe,
        .port_remove = mos7840_port_remove,
        .read_bulk_callback = mos7840_bulk_in_callback,
        .suspend = mos7840_suspend,
        .resume = mos7840_resume,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &moschip7840_4port_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");