// SPDX-License-Identifier: GPL-2.0+
/*
 *      mxuport.c - MOXA UPort series driver
 *
 *      Copyright (c) 2006 Moxa Technologies Co., Ltd.
 *      Copyright (c) 2013 Andrew Lunn <andrew@lunn.ch>
 *
 *      Supports the following Moxa USB to serial converters:
 *       2 ports : UPort 1250, UPort 1250I
 *       4 ports : UPort 1410, UPort 1450, UPort 1450I
 *       8 ports : UPort 1610-8, UPort 1650-8
 *      16 ports : UPort 1610-16, UPort 1650-16
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/firmware.h>
#include <linux/jiffies.h>
#include <linux/serial.h>
#include <linux/serial_reg.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <asm/unaligned.h>

/* Definitions for the vendor ID and device ID */
#define MX_USBSERIAL_VID        0x110A
#define MX_UPORT1250_PID        0x1250
#define MX_UPORT1251_PID        0x1251
#define MX_UPORT1410_PID        0x1410
#define MX_UPORT1450_PID        0x1450
#define MX_UPORT1451_PID        0x1451
#define MX_UPORT1618_PID        0x1618
#define MX_UPORT1658_PID        0x1658
#define MX_UPORT1613_PID        0x1613
#define MX_UPORT1653_PID        0x1653

/* Definitions for USB info */
#define HEADER_SIZE             4
#define EVENT_LENGTH            8
#define DOWN_BLOCK_SIZE         64

/* Definitions for firmware info */
#define VER_ADDR_1              0x20
#define VER_ADDR_2              0x24
#define VER_ADDR_3              0x28

/* Definitions for USB vendor request */
#define RQ_VENDOR_NONE                  0x00
#define RQ_VENDOR_SET_BAUD              0x01 /* Set baud rate */
#define RQ_VENDOR_SET_LINE              0x02 /* Set line status */
#define RQ_VENDOR_SET_CHARS             0x03 /* Set Xon/Xoff chars */
#define RQ_VENDOR_SET_RTS               0x04 /* Set RTS */
#define RQ_VENDOR_SET_DTR               0x05 /* Set DTR */
#define RQ_VENDOR_SET_XONXOFF           0x06 /* Set auto Xon/Xoff */
#define RQ_VENDOR_SET_RX_HOST_EN        0x07 /* Set RX host enable */
#define RQ_VENDOR_SET_OPEN              0x08 /* Set open/close port */
#define RQ_VENDOR_PURGE                 0x09 /* Purge Rx/Tx buffer */
#define RQ_VENDOR_SET_MCR               0x0A /* Set MCR register */
#define RQ_VENDOR_SET_BREAK             0x0B /* Set Break signal */

#define RQ_VENDOR_START_FW_DOWN         0x0C /* Start firmware download */
#define RQ_VENDOR_STOP_FW_DOWN          0x0D /* Stop firmware download */
#define RQ_VENDOR_QUERY_FW_READY        0x0E /* Query if new firmware ready */

#define RQ_VENDOR_SET_FIFO_DISABLE      0x0F /* Set fifo disable */
#define RQ_VENDOR_SET_INTERFACE         0x10 /* Set interface */
#define RQ_VENDOR_SET_HIGH_PERFOR       0x11 /* Set hi-performance */

#define RQ_VENDOR_ERASE_BLOCK           0x12 /* Erase flash block */
#define RQ_VENDOR_WRITE_PAGE            0x13 /* Write flash page */
#define RQ_VENDOR_PREPARE_WRITE         0x14 /* Prepare write flash */
#define RQ_VENDOR_CONFIRM_WRITE         0x15 /* Confirm write flash */
#define RQ_VENDOR_LOCATE                0x16 /* Locate the device */

#define RQ_VENDOR_START_ROM_DOWN        0x17 /* Start firmware download */
#define RQ_VENDOR_ROM_DATA              0x18 /* Rom file data */
#define RQ_VENDOR_STOP_ROM_DOWN         0x19 /* Stop firmware download */
#define RQ_VENDOR_FW_DATA               0x20 /* Firmware data */

#define RQ_VENDOR_RESET_DEVICE          0x23 /* Try to reset the device */
#define RQ_VENDOR_QUERY_FW_CONFIG       0x24

#define RQ_VENDOR_GET_VERSION           0x81 /* Get firmware version */
#define RQ_VENDOR_GET_PAGE              0x82 /* Read flash page */
#define RQ_VENDOR_GET_ROM_PROC          0x83 /* Get ROM process state */

#define RQ_VENDOR_GET_INQUEUE           0x84 /* Data in input buffer */
#define RQ_VENDOR_GET_OUTQUEUE          0x85 /* Data in output buffer */

#define RQ_VENDOR_GET_MSR               0x86 /* Get modem status register */

/* Definitions for UPort event type */
#define UPORT_EVENT_NONE                0 /* None */
#define UPORT_EVENT_TXBUF_THRESHOLD     1 /* Tx buffer threshold */
#define UPORT_EVENT_SEND_NEXT           2 /* Send next */
#define UPORT_EVENT_MSR                 3 /* Modem status */
#define UPORT_EVENT_LSR                 4 /* Line status */
#define UPORT_EVENT_MCR                 5 /* Modem control */

/* Definitions for serial event type */
#define SERIAL_EV_CTS                   0x0008  /* CTS changed state */
#define SERIAL_EV_DSR                   0x0010  /* DSR changed state */
#define SERIAL_EV_RLSD                  0x0020  /* RLSD changed state */

/* Definitions for modem control event type */
#define SERIAL_EV_XOFF                  0x40    /* XOFF received */

/* Definitions for line control of communication */
#define MX_WORDLENGTH_5                 5
#define MX_WORDLENGTH_6                 6
#define MX_WORDLENGTH_7                 7
#define MX_WORDLENGTH_8                 8

#define MX_PARITY_NONE                  0
#define MX_PARITY_ODD                   1
#define MX_PARITY_EVEN                  2
#define MX_PARITY_MARK                  3
#define MX_PARITY_SPACE                 4

#define MX_STOP_BITS_1                  0
#define MX_STOP_BITS_1_5                1
#define MX_STOP_BITS_2                  2

#define MX_RTS_DISABLE                  0x0
#define MX_RTS_ENABLE                   0x1
#define MX_RTS_HW                       0x2
#define MX_RTS_NO_CHANGE                0x3 /* Flag, not valid register value*/

#define MX_INT_RS232                    0
#define MX_INT_2W_RS485                 1
#define MX_INT_RS422                    2
#define MX_INT_4W_RS485                 3

/* Definitions for holding reason */
#define MX_WAIT_FOR_CTS                 0x0001
#define MX_WAIT_FOR_DSR                 0x0002
#define MX_WAIT_FOR_DCD                 0x0004
#define MX_WAIT_FOR_XON                 0x0008
#define MX_WAIT_FOR_START_TX            0x0010
#define MX_WAIT_FOR_UNTHROTTLE          0x0020
#define MX_WAIT_FOR_LOW_WATER           0x0040
#define MX_WAIT_FOR_SEND_NEXT           0x0080

#define MX_UPORT_2_PORT                 BIT(0)
#define MX_UPORT_4_PORT                 BIT(1)
#define MX_UPORT_8_PORT                 BIT(2)
#define MX_UPORT_16_PORT                BIT(3)

/* This structure holds all of the local port information */
struct mxuport_port {
        u8 mcr_state;           /* Last MCR state */
        u8 msr_state;           /* Last MSR state */
        struct mutex mutex;     /* Protects mcr_state */
        spinlock_t spinlock;    /* Protects msr_state */
};

/* Table of devices that work with this driver */
static const struct usb_device_id mxuport_idtable[] = {
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1250_PID),
          .driver_info = MX_UPORT_2_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1251_PID),
          .driver_info = MX_UPORT_2_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1410_PID),
          .driver_info = MX_UPORT_4_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1450_PID),
          .driver_info = MX_UPORT_4_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1451_PID),
          .driver_info = MX_UPORT_4_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1618_PID),
          .driver_info = MX_UPORT_8_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1658_PID),
          .driver_info = MX_UPORT_8_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1613_PID),
          .driver_info = MX_UPORT_16_PORT },
        { USB_DEVICE(MX_USBSERIAL_VID, MX_UPORT1653_PID),
          .driver_info = MX_UPORT_16_PORT },
        {}                      /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, mxuport_idtable);

/*
 * Add a four byte header containing the port number and the number of
 * bytes of data in the message. Return the number of bytes in the
 * buffer.
 */
static int mxuport_prepare_write_buffer(struct usb_serial_port *port,
                                        void *dest, size_t size)
{
        u8 *buf = dest;
        int count;

        count = kfifo_out_locked(&port->write_fifo, buf + HEADER_SIZE,
                                 size - HEADER_SIZE,
                                 &port->lock);

        put_unaligned_be16(port->port_number, buf);
        put_unaligned_be16(count, buf + 2);

        dev_dbg(&port->dev, "%s - size %zd count %d\n", __func__,
                size, count);

        return count + HEADER_SIZE;
}

/* Read the given buffer in from the control pipe. */
static int mxuport_recv_ctrl_urb(struct usb_serial *serial,
                                 u8 request, u16 value, u16 index,
                                 u8 *data, size_t size)
{
        int status;

        status = usb_control_msg(serial->dev,
                                 usb_rcvctrlpipe(serial->dev, 0),
                                 request,
                                 (USB_DIR_IN | USB_TYPE_VENDOR |
                                  USB_RECIP_DEVICE), value, index,
                                 data, size,
                                 USB_CTRL_GET_TIMEOUT);
        if (status < 0) {
                dev_err(&serial->interface->dev,
                        "%s - usb_control_msg failed (%d)\n",
                        __func__, status);
                return status;
        }

        if (status != size) {
                dev_err(&serial->interface->dev,
                        "%s - short read (%d / %zd)\n",
                        __func__, status, size);
                return -EIO;
        }

        return status;
}

/* Write the given buffer out to the control pipe.  */
static int mxuport_send_ctrl_data_urb(struct usb_serial *serial,
                                      u8 request,
                                      u16 value, u16 index,
                                      u8 *data, size_t size)
{
        int status;

        status = usb_control_msg(serial->dev,
                                 usb_sndctrlpipe(serial->dev, 0),
                                 request,
                                 (USB_DIR_OUT | USB_TYPE_VENDOR |
                                  USB_RECIP_DEVICE), value, index,
                                 data, size,
                                 USB_CTRL_SET_TIMEOUT);
        if (status < 0) {
                dev_err(&serial->interface->dev,
                        "%s - usb_control_msg failed (%d)\n",
                        __func__, status);
                return status;
        }

        return 0;
}

/* Send a vendor request without any data */
static int mxuport_send_ctrl_urb(struct usb_serial *serial,
                                 u8 request, u16 value, u16 index)
{
        return mxuport_send_ctrl_data_urb(serial, request, value, index,
                                          NULL, 0);
}

/*
 * mxuport_throttle - throttle function of driver
 *
 * This function is called by the tty driver when it wants to stop the
 * data being read from the port. Since all the data comes over one
 * bulk in endpoint, we cannot stop submitting urbs by setting
 * port->throttle. Instead tell the device to stop sending us data for
 * the port.
 */
static void mxuport_throttle(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;

        dev_dbg(&port->dev, "%s\n", __func__);

        mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_RX_HOST_EN,
                              0, port->port_number);
}

/*
 * mxuport_unthrottle - unthrottle function of driver
 *
 * This function is called by the tty driver when it wants to resume
 * the data being read from the port. Tell the device it can resume
 * sending us received data from the port.
 */
static void mxuport_unthrottle(struct tty_struct *tty)
{

        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;

        dev_dbg(&port->dev, "%s\n", __func__);

        mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_RX_HOST_EN,
                              1, port->port_number);
}

/*
 * Processes one chunk of data received for a port.  Mostly a copy of
 * usb_serial_generic_process_read_urb().
 */
static void mxuport_process_read_urb_data(struct usb_serial_port *port,
                                          char *data, int size)
{
        int i;

        if (port->sysrq) {
                for (i = 0; i < size; i++, data++) {
                        if (!usb_serial_handle_sysrq_char(port, *data))
                                tty_insert_flip_char(&port->port, *data,
                                                     TTY_NORMAL);
                }
        } else {
                tty_insert_flip_string(&port->port, data, size);
        }
        tty_flip_buffer_push(&port->port);
}

static void mxuport_msr_event(struct usb_serial_port *port, u8 buf[4])
{
        struct mxuport_port *mxport = usb_get_serial_port_data(port);
        u8 rcv_msr_hold = buf[2] & 0xF0;
        u16 rcv_msr_event = get_unaligned_be16(buf);
        unsigned long flags;

        if (rcv_msr_event == 0)
                return;

        /* Update MSR status */
        spin_lock_irqsave(&mxport->spinlock, flags);

        dev_dbg(&port->dev, "%s - current MSR status = 0x%x\n",
                __func__, mxport->msr_state);

        if (rcv_msr_hold & UART_MSR_CTS) {
                mxport->msr_state |= UART_MSR_CTS;
                dev_dbg(&port->dev, "%s - CTS high\n", __func__);
        } else {
                mxport->msr_state &= ~UART_MSR_CTS;
                dev_dbg(&port->dev, "%s - CTS low\n", __func__);
        }

        if (rcv_msr_hold & UART_MSR_DSR) {
                mxport->msr_state |= UART_MSR_DSR;
                dev_dbg(&port->dev, "%s - DSR high\n", __func__);
        } else {
                mxport->msr_state &= ~UART_MSR_DSR;
                dev_dbg(&port->dev, "%s - DSR low\n", __func__);
        }

        if (rcv_msr_hold & UART_MSR_DCD) {
                mxport->msr_state |= UART_MSR_DCD;
                dev_dbg(&port->dev, "%s - DCD high\n", __func__);
        } else {
                mxport->msr_state &= ~UART_MSR_DCD;
                dev_dbg(&port->dev, "%s - DCD low\n", __func__);
        }
        spin_unlock_irqrestore(&mxport->spinlock, flags);

        if (rcv_msr_event &
            (SERIAL_EV_CTS | SERIAL_EV_DSR | SERIAL_EV_RLSD)) {

                if (rcv_msr_event & SERIAL_EV_CTS) {
                        port->icount.cts++;
                        dev_dbg(&port->dev, "%s - CTS change\n", __func__);
                }

                if (rcv_msr_event & SERIAL_EV_DSR) {
                        port->icount.dsr++;
                        dev_dbg(&port->dev, "%s - DSR change\n", __func__);
                }

                if (rcv_msr_event & SERIAL_EV_RLSD) {
                        port->icount.dcd++;
                        dev_dbg(&port->dev, "%s - DCD change\n", __func__);
                }
                wake_up_interruptible(&port->port.delta_msr_wait);
        }
}

static void mxuport_lsr_event(struct usb_serial_port *port, u8 buf[4])
{
        u8 lsr_event = buf[2];

        if (lsr_event & UART_LSR_BI) {
                port->icount.brk++;
                dev_dbg(&port->dev, "%s - break error\n", __func__);
        }

        if (lsr_event & UART_LSR_FE) {
                port->icount.frame++;
                dev_dbg(&port->dev, "%s - frame error\n", __func__);
        }

        if (lsr_event & UART_LSR_PE) {
                port->icount.parity++;
                dev_dbg(&port->dev, "%s - parity error\n", __func__);
        }

        if (lsr_event & UART_LSR_OE) {
                port->icount.overrun++;
                dev_dbg(&port->dev, "%s - overrun error\n", __func__);
        }
}

/*
 * When something interesting happens, modem control lines XON/XOFF
 * etc, the device sends an event. Process these events.
 */
static void mxuport_process_read_urb_event(struct usb_serial_port *port,
                                           u8 buf[4], u32 event)
{
        dev_dbg(&port->dev, "%s - receive event : %04x\n", __func__, event);

        switch (event) {
        case UPORT_EVENT_SEND_NEXT:
                /*
                 * Sent as part of the flow control on device buffers.
                 * Not currently used.
                 */
                break;
        case UPORT_EVENT_MSR:
                mxuport_msr_event(port, buf);
                break;
        case UPORT_EVENT_LSR:
                mxuport_lsr_event(port, buf);
                break;
        case UPORT_EVENT_MCR:
                /*
                 * Event to indicate a change in XON/XOFF from the
                 * peer.  Currently not used. We just continue
                 * sending the device data and it will buffer it if
                 * needed. This event could be used for flow control
                 * between the host and the device.
                 */
                break;
        default:
                dev_dbg(&port->dev, "Unexpected event\n");
                break;
        }
}

/*
 * One URB can contain data for multiple ports. Demultiplex the data,
 * checking the port exists, is opened and the message is valid.
 */
static void mxuport_process_read_urb_demux_data(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct usb_serial *serial = port->serial;
        u8 *data = urb->transfer_buffer;
        u8 *end = data + urb->actual_length;
        struct usb_serial_port *demux_port;
        u8 *ch;
        u16 rcv_port;
        u16 rcv_len;

        while (data < end) {
                if (data + HEADER_SIZE > end) {
                        dev_warn(&port->dev, "%s - message with short header\n",
                                 __func__);
                        return;
                }

                rcv_port = get_unaligned_be16(data);
                if (rcv_port >= serial->num_ports) {
                        dev_warn(&port->dev, "%s - message for invalid port\n",
                                 __func__);
                        return;
                }

                demux_port = serial->port[rcv_port];
                rcv_len = get_unaligned_be16(data + 2);
                if (!rcv_len || data + HEADER_SIZE + rcv_len > end) {
                        dev_warn(&port->dev, "%s - short data\n", __func__);
                        return;
                }

                if (tty_port_initialized(&demux_port->port)) {
                        ch = data + HEADER_SIZE;
                        mxuport_process_read_urb_data(demux_port, ch, rcv_len);
                } else {
                        dev_dbg(&demux_port->dev, "%s - data for closed port\n",
                                __func__);
                }
                data += HEADER_SIZE + rcv_len;
        }
}

/*
 * One URB can contain events for multiple ports. Demultiplex the event,
 * checking the port exists, and is opened.
 */
static void mxuport_process_read_urb_demux_event(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct usb_serial *serial = port->serial;
        u8 *data = urb->transfer_buffer;
        u8 *end = data + urb->actual_length;
        struct usb_serial_port *demux_port;
        u8 *ch;
        u16 rcv_port;
        u16 rcv_event;

        while (data < end) {
                if (data + EVENT_LENGTH > end) {
                        dev_warn(&port->dev, "%s - message with short event\n",
                                 __func__);
                        return;
                }

                rcv_port = get_unaligned_be16(data);
                if (rcv_port >= serial->num_ports) {
                        dev_warn(&port->dev, "%s - message for invalid port\n",
                                 __func__);
                        return;
                }

                demux_port = serial->port[rcv_port];
                if (tty_port_initialized(&demux_port->port)) {
                        ch = data + HEADER_SIZE;
                        rcv_event = get_unaligned_be16(data + 2);
                        mxuport_process_read_urb_event(demux_port, ch,
                                                       rcv_event);
                } else {
                        dev_dbg(&demux_port->dev,
                                "%s - event for closed port\n", __func__);
                }
                data += EVENT_LENGTH;
        }
}

/*
 * This is called when we have received data on the bulk in
 * endpoint. Depending on which port it was received on, it can
 * contain serial data or events.
 */
static void mxuport_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct usb_serial *serial = port->serial;

        if (port == serial->port[0])
                mxuport_process_read_urb_demux_data(urb);

        if (port == serial->port[1])
                mxuport_process_read_urb_demux_event(urb);
}

/*
 * Ask the device how many bytes it has queued to be sent out. If
 * there are none, return true.
 */
static bool mxuport_tx_empty(struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;
        bool is_empty = true;
        u32 txlen;
        u8 *len_buf;
        int err;

        len_buf = kzalloc(4, GFP_KERNEL);
        if (!len_buf)
                goto out;

        err = mxuport_recv_ctrl_urb(serial, RQ_VENDOR_GET_OUTQUEUE, 0,
                                    port->port_number, len_buf, 4);
        if (err < 0)
                goto out;

        txlen = get_unaligned_be32(len_buf);
        dev_dbg(&port->dev, "%s - tx len = %u\n", __func__, txlen);

        if (txlen != 0)
                is_empty = false;

out:
        kfree(len_buf);
        return is_empty;
}

static int mxuport_set_mcr(struct usb_serial_port *port, u8 mcr_state)
{
        struct usb_serial *serial = port->serial;
        int err;

        dev_dbg(&port->dev, "%s - %02x\n", __func__, mcr_state);

        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_MCR,
                                    mcr_state, port->port_number);
        if (err)
                dev_err(&port->dev, "%s - failed to change MCR\n", __func__);

        return err;
}

static int mxuport_set_dtr(struct usb_serial_port *port, int on)
{
        struct mxuport_port *mxport = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        int err;

        mutex_lock(&mxport->mutex);

        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_DTR,
                                    !!on, port->port_number);
        if (!err) {
                if (on)
                        mxport->mcr_state |= UART_MCR_DTR;
                else
                        mxport->mcr_state &= ~UART_MCR_DTR;
        }

        mutex_unlock(&mxport->mutex);

        return err;
}

static int mxuport_set_rts(struct usb_serial_port *port, u8 state)
{
        struct mxuport_port *mxport = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        int err;
        u8 mcr_state;

        mutex_lock(&mxport->mutex);
        mcr_state = mxport->mcr_state;

        switch (state) {
        case MX_RTS_DISABLE:
                mcr_state &= ~UART_MCR_RTS;
                break;
        case MX_RTS_ENABLE:
                mcr_state |= UART_MCR_RTS;
                break;
        case MX_RTS_HW:
                /*
                 * Do not update mxport->mcr_state when doing hardware
                 * flow control.
                 */
                break;
        default:
                /*
                 * Should not happen, but somebody might try passing
                 * MX_RTS_NO_CHANGE, which is not valid.
                 */
                err = -EINVAL;
                goto out;
        }
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_RTS,
                                    state, port->port_number);
        if (!err)
                mxport->mcr_state = mcr_state;

out:
        mutex_unlock(&mxport->mutex);

        return err;
}

static void mxuport_dtr_rts(struct usb_serial_port *port, int on)
{
        struct mxuport_port *mxport = usb_get_serial_port_data(port);
        u8 mcr_state;
        int err;

        mutex_lock(&mxport->mutex);
        mcr_state = mxport->mcr_state;

        if (on)
                mcr_state |= (UART_MCR_RTS | UART_MCR_DTR);
        else
                mcr_state &= ~(UART_MCR_RTS | UART_MCR_DTR);

        err = mxuport_set_mcr(port, mcr_state);
        if (!err)
                mxport->mcr_state = mcr_state;

        mutex_unlock(&mxport->mutex);
}

static int mxuport_tiocmset(struct tty_struct *tty, unsigned int set,
                            unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct mxuport_port *mxport = usb_get_serial_port_data(port);
        int err;
        u8 mcr_state;

        mutex_lock(&mxport->mutex);
        mcr_state = mxport->mcr_state;

        if (set & TIOCM_RTS)
                mcr_state |= UART_MCR_RTS;

        if (set & TIOCM_DTR)
                mcr_state |= UART_MCR_DTR;

        if (clear & TIOCM_RTS)
                mcr_state &= ~UART_MCR_RTS;

        if (clear & TIOCM_DTR)
                mcr_state &= ~UART_MCR_DTR;

        err = mxuport_set_mcr(port, mcr_state);
        if (!err)
                mxport->mcr_state = mcr_state;

        mutex_unlock(&mxport->mutex);

        return err;
}

static int mxuport_tiocmget(struct tty_struct *tty)
{
        struct mxuport_port *mxport;
        struct usb_serial_port *port = tty->driver_data;
        unsigned int result;
        unsigned long flags;
        unsigned int msr;
        unsigned int mcr;

        mxport = usb_get_serial_port_data(port);

        mutex_lock(&mxport->mutex);
        spin_lock_irqsave(&mxport->spinlock, flags);

        msr = mxport->msr_state;
        mcr = mxport->mcr_state;

        spin_unlock_irqrestore(&mxport->spinlock, flags);
        mutex_unlock(&mxport->mutex);

        result = (((mcr & UART_MCR_DTR) ? TIOCM_DTR : 0) |      /* 0x002 */
                  ((mcr & UART_MCR_RTS) ? TIOCM_RTS : 0) |      /* 0x004 */
                  ((msr & UART_MSR_CTS) ? TIOCM_CTS : 0) |      /* 0x020 */
                  ((msr & UART_MSR_DCD) ? TIOCM_CAR : 0) |      /* 0x040 */
                  ((msr & UART_MSR_RI) ? TIOCM_RI : 0) |        /* 0x080 */
                  ((msr & UART_MSR_DSR) ? TIOCM_DSR : 0));      /* 0x100 */

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

        return result;
}

static int mxuport_set_termios_flow(struct tty_struct *tty,
                                    struct ktermios *old_termios,
                                    struct usb_serial_port *port,
                                    struct usb_serial *serial)
{
        u8 xon = START_CHAR(tty);
        u8 xoff = STOP_CHAR(tty);
        int enable;
        int err;
        u8 *buf;
        u8 rts;

        buf = kmalloc(2, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /* S/W flow control settings */
        if (I_IXOFF(tty) || I_IXON(tty)) {
                enable = 1;
                buf[0] = xon;
                buf[1] = xoff;

                err = mxuport_send_ctrl_data_urb(serial, RQ_VENDOR_SET_CHARS,
                                                 0, port->port_number,
                                                 buf, 2);
                if (err)
                        goto out;

                dev_dbg(&port->dev, "%s - XON = 0x%02x, XOFF = 0x%02x\n",
                        __func__, xon, xoff);
        } else {
                enable = 0;
        }

        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_XONXOFF,
                                    enable, port->port_number);
        if (err)
                goto out;

        rts = MX_RTS_NO_CHANGE;

        /* H/W flow control settings */
        if (!old_termios ||
            C_CRTSCTS(tty) != (old_termios->c_cflag & CRTSCTS)) {
                if (C_CRTSCTS(tty))
                        rts = MX_RTS_HW;
                else
                        rts = MX_RTS_ENABLE;
        }

        if (C_BAUD(tty)) {
                if (old_termios && (old_termios->c_cflag & CBAUD) == B0) {
                        /* Raise DTR and RTS */
                        if (C_CRTSCTS(tty))
                                rts = MX_RTS_HW;
                        else
                                rts = MX_RTS_ENABLE;
                        mxuport_set_dtr(port, 1);
                }
        } else {
                /* Drop DTR and RTS */
                rts = MX_RTS_DISABLE;
                mxuport_set_dtr(port, 0);
        }

        if (rts != MX_RTS_NO_CHANGE)
                err = mxuport_set_rts(port, rts);

out:
        kfree(buf);
        return err;
}

static void mxuport_set_termios(struct tty_struct *tty,
                                struct usb_serial_port *port,
                                struct ktermios *old_termios)
{
        struct usb_serial *serial = port->serial;
        u8 *buf;
        u8 data_bits;
        u8 stop_bits;
        u8 parity;
        int baud;
        int err;

        if (old_termios &&
            !tty_termios_hw_change(&tty->termios, old_termios) &&
            tty->termios.c_iflag == old_termios->c_iflag) {
                dev_dbg(&port->dev, "%s - nothing to change\n", __func__);
                return;
        }

        buf = kmalloc(4, GFP_KERNEL);
        if (!buf)
                return;

        /* Set data bit of termios */
        switch (C_CSIZE(tty)) {
        case CS5:
                data_bits = MX_WORDLENGTH_5;
                break;
        case CS6:
                data_bits = MX_WORDLENGTH_6;
                break;
        case CS7:
                data_bits = MX_WORDLENGTH_7;
                break;
        case CS8:
        default:
                data_bits = MX_WORDLENGTH_8;
                break;
        }

        /* Set parity of termios */
        if (C_PARENB(tty)) {
                if (C_CMSPAR(tty)) {
                        if (C_PARODD(tty))
                                parity = MX_PARITY_MARK;
                        else
                                parity = MX_PARITY_SPACE;
                } else {
                        if (C_PARODD(tty))
                                parity = MX_PARITY_ODD;
                        else
                                parity = MX_PARITY_EVEN;
                }
        } else {
                parity = MX_PARITY_NONE;
        }

        /* Set stop bit of termios */
        if (C_CSTOPB(tty))
                stop_bits = MX_STOP_BITS_2;
        else
                stop_bits = MX_STOP_BITS_1;

        buf[0] = data_bits;
        buf[1] = parity;
        buf[2] = stop_bits;
        buf[3] = 0;

        err = mxuport_send_ctrl_data_urb(serial, RQ_VENDOR_SET_LINE,
                                         0, port->port_number, buf, 4);
        if (err)
                goto out;

        err = mxuport_set_termios_flow(tty, old_termios, port, serial);
        if (err)
                goto out;

        baud = tty_get_baud_rate(tty);
        if (!baud)
                baud = 9600;

        /* Note: Little Endian */
        put_unaligned_le32(baud, buf);

        err = mxuport_send_ctrl_data_urb(serial, RQ_VENDOR_SET_BAUD,
                                         0, port->port_number,
                                         buf, 4);
        if (err)
                goto out;

        dev_dbg(&port->dev, "baud_rate  : %d\n", baud);
        dev_dbg(&port->dev, "data_bits  : %d\n", data_bits);
        dev_dbg(&port->dev, "parity     : %d\n", parity);
        dev_dbg(&port->dev, "stop_bits  : %d\n", stop_bits);

out:
        kfree(buf);
}

/*
 * Determine how many ports this device has dynamically.  It will be
 * called after the probe() callback is called, but before attach().
 */
static int mxuport_calc_num_ports(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds)
{
        unsigned long features = (unsigned long)usb_get_serial_data(serial);
        int num_ports;
        int i;

        if (features & MX_UPORT_2_PORT) {
                num_ports = 2;
        } else if (features & MX_UPORT_4_PORT) {
                num_ports = 4;
        } else if (features & MX_UPORT_8_PORT) {
                num_ports = 8;
        } else if (features & MX_UPORT_16_PORT) {
                num_ports = 16;
        } else {
                dev_warn(&serial->interface->dev,
                                "unknown device, assuming two ports\n");
                num_ports = 2;
        }

        /*
         * Setup bulk-out endpoint multiplexing. All ports share the same
         * bulk-out endpoint.
         */
        BUILD_BUG_ON(ARRAY_SIZE(epds->bulk_out) < 16);

        for (i = 1; i < num_ports; ++i)
                epds->bulk_out[i] = epds->bulk_out[0];

        epds->num_bulk_out = num_ports;

        return num_ports;
}

/* Get the version of the firmware currently running. */
static int mxuport_get_fw_version(struct usb_serial *serial, u32 *version)
{
        u8 *ver_buf;
        int err;

        ver_buf = kzalloc(4, GFP_KERNEL);
        if (!ver_buf)
                return -ENOMEM;

        /* Get firmware version from SDRAM */
        err = mxuport_recv_ctrl_urb(serial, RQ_VENDOR_GET_VERSION, 0, 0,
                                    ver_buf, 4);
        if (err != 4) {
                err = -EIO;
                goto out;
        }

        *version = (ver_buf[0] << 16) | (ver_buf[1] << 8) | ver_buf[2];
        err = 0;
out:
        kfree(ver_buf);
        return err;
}

/* Given a firmware blob, download it to the device. */
static int mxuport_download_fw(struct usb_serial *serial,
                               const struct firmware *fw_p)

{
        u8 *fw_buf;
        size_t txlen;
        size_t fwidx;
        int err;

        fw_buf = kmalloc(DOWN_BLOCK_SIZE, GFP_KERNEL);
        if (!fw_buf)
                return -ENOMEM;

        dev_dbg(&serial->interface->dev, "Starting firmware download...\n");
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_START_FW_DOWN, 0, 0);
        if (err)
                goto out;

        fwidx = 0;
        do {
                txlen = min_t(size_t, (fw_p->size - fwidx), DOWN_BLOCK_SIZE);

                memcpy(fw_buf, &fw_p->data[fwidx], txlen);
                err = mxuport_send_ctrl_data_urb(serial, RQ_VENDOR_FW_DATA,
                                                 0, 0, fw_buf, txlen);
                if (err) {
                        mxuport_send_ctrl_urb(serial, RQ_VENDOR_STOP_FW_DOWN,
                                              0, 0);
                        goto out;
                }

                fwidx += txlen;
                usleep_range(1000, 2000);

        } while (fwidx < fw_p->size);

        msleep(1000);
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_STOP_FW_DOWN, 0, 0);
        if (err)
                goto out;

        msleep(1000);
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_QUERY_FW_READY, 0, 0);

out:
        kfree(fw_buf);
        return err;
}

static int mxuport_probe(struct usb_serial *serial,
                         const struct usb_device_id *id)
{
        u16 productid = le16_to_cpu(serial->dev->descriptor.idProduct);
        const struct firmware *fw_p = NULL;
        u32 version;
        int local_ver;
        char buf[32];
        int err;

        /* Load our firmware */
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_QUERY_FW_CONFIG, 0, 0);
        if (err) {
                mxuport_send_ctrl_urb(serial, RQ_VENDOR_RESET_DEVICE, 0, 0);
                return err;
        }

        err = mxuport_get_fw_version(serial, &version);
        if (err < 0)
                return err;

        dev_dbg(&serial->interface->dev, "Device firmware version v%x.%x.%x\n",
                (version & 0xff0000) >> 16,
                (version & 0xff00) >> 8,
                (version & 0xff));

        snprintf(buf, sizeof(buf) - 1, "moxa/moxa-%04x.fw", productid);

        err = request_firmware(&fw_p, buf, &serial->interface->dev);
        if (err) {
                dev_warn(&serial->interface->dev, "Firmware %s not found\n",
                         buf);

                /* Use the firmware already in the device */
                err = 0;
        } else {
                local_ver = ((fw_p->data[VER_ADDR_1] << 16) |
                             (fw_p->data[VER_ADDR_2] << 8) |
                             fw_p->data[VER_ADDR_3]);
                dev_dbg(&serial->interface->dev,
                        "Available firmware version v%x.%x.%x\n",
                        fw_p->data[VER_ADDR_1], fw_p->data[VER_ADDR_2],
                        fw_p->data[VER_ADDR_3]);
                if (local_ver > version) {
                        err = mxuport_download_fw(serial, fw_p);
                        if (err)
                                goto out;
                        err  = mxuport_get_fw_version(serial, &version);
                        if (err < 0)
                                goto out;
                }
        }

        dev_info(&serial->interface->dev,
                 "Using device firmware version v%x.%x.%x\n",
                 (version & 0xff0000) >> 16,
                 (version & 0xff00) >> 8,
                 (version & 0xff));

        /*
         * Contains the features of this hardware. Store away for
         * later use, eg, number of ports.
         */
        usb_set_serial_data(serial, (void *)id->driver_info);
out:
        if (fw_p)
                release_firmware(fw_p);
        return err;
}


static int mxuport_port_probe(struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;
        struct mxuport_port *mxport;
        int err;

        mxport = devm_kzalloc(&port->dev, sizeof(struct mxuport_port),
                              GFP_KERNEL);
        if (!mxport)
                return -ENOMEM;

        mutex_init(&mxport->mutex);
        spin_lock_init(&mxport->spinlock);

        /* Set the port private data */
        usb_set_serial_port_data(port, mxport);

        /* Set FIFO (Enable) */
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_FIFO_DISABLE,
                                    0, port->port_number);
        if (err)
                return err;

        /* Set transmission mode (Hi-Performance) */
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_HIGH_PERFOR,
                                    0, port->port_number);
        if (err)
                return err;

        /* Set interface (RS-232) */
        return mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_INTERFACE,
                                     MX_INT_RS232,
                                     port->port_number);
}

static int mxuport_attach(struct usb_serial *serial)
{
        struct usb_serial_port *port0 = serial->port[0];
        struct usb_serial_port *port1 = serial->port[1];
        int err;

        /*
         * All data from the ports is received on the first bulk in
         * endpoint, with a multiplex header. The second bulk in is
         * used for events.
         *
         * Start to read from the device.
         */
        err = usb_serial_generic_submit_read_urbs(port0, GFP_KERNEL);
        if (err)
                return err;

        err = usb_serial_generic_submit_read_urbs(port1, GFP_KERNEL);
        if (err) {
                usb_serial_generic_close(port0);
                return err;
        }

        return 0;
}

static void mxuport_release(struct usb_serial *serial)
{
        struct usb_serial_port *port0 = serial->port[0];
        struct usb_serial_port *port1 = serial->port[1];

        usb_serial_generic_close(port1);
        usb_serial_generic_close(port0);
}

static int mxuport_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct mxuport_port *mxport = usb_get_serial_port_data(port);
        struct usb_serial *serial = port->serial;
        int err;

        /* Set receive host (enable) */
        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_RX_HOST_EN,
                                    1, port->port_number);
        if (err)
                return err;

        err = mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_OPEN,
                                    1, port->port_number);
        if (err) {
                mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_RX_HOST_EN,
                                      0, port->port_number);
                return err;
        }

        /* Initial port termios */
        if (tty)
                mxuport_set_termios(tty, port, NULL);

        /*
         * TODO: use RQ_VENDOR_GET_MSR, once we know what it
         * returns.
         */
        mxport->msr_state = 0;

        return err;
}

static void mxuport_close(struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;

        mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_OPEN, 0,
                              port->port_number);

        mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_RX_HOST_EN, 0,
                              port->port_number);
}

/* Send a break to the port. */
static void mxuport_break_ctl(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;
        int enable;

        if (break_state == -1) {
                enable = 1;
                dev_dbg(&port->dev, "%s - sending break\n", __func__);
        } else {
                enable = 0;
                dev_dbg(&port->dev, "%s - clearing break\n", __func__);
        }

        mxuport_send_ctrl_urb(serial, RQ_VENDOR_SET_BREAK,
                              enable, port->port_number);
}

static int mxuport_resume(struct usb_serial *serial)
{
        struct usb_serial_port *port;
        int c = 0;
        int i;
        int r;

        for (i = 0; i < 2; i++) {
                port = serial->port[i];

                r = usb_serial_generic_submit_read_urbs(port, GFP_NOIO);
                if (r < 0)
                        c++;
        }

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

                r = usb_serial_generic_write_start(port, GFP_NOIO);
                if (r < 0)
                        c++;
        }

        return c ? -EIO : 0;
}

static struct usb_serial_driver mxuport_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "mxuport",
        },
        .description            = "MOXA UPort",
        .id_table               = mxuport_idtable,
        .num_bulk_in            = 2,
        .num_bulk_out           = 1,
        .probe                  = mxuport_probe,
        .port_probe             = mxuport_port_probe,
        .attach                 = mxuport_attach,
        .release                = mxuport_release,
        .calc_num_ports         = mxuport_calc_num_ports,
        .open                   = mxuport_open,
        .close                  = mxuport_close,
        .set_termios            = mxuport_set_termios,
        .break_ctl              = mxuport_break_ctl,
        .tx_empty               = mxuport_tx_empty,
        .tiocmiwait             = usb_serial_generic_tiocmiwait,
        .get_icount             = usb_serial_generic_get_icount,
        .throttle               = mxuport_throttle,
        .unthrottle             = mxuport_unthrottle,
        .tiocmget               = mxuport_tiocmget,
        .tiocmset               = mxuport_tiocmset,
        .dtr_rts                = mxuport_dtr_rts,
        .process_read_urb       = mxuport_process_read_urb,
        .prepare_write_buffer   = mxuport_prepare_write_buffer,
        .resume                 = mxuport_resume,
};

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

module_usb_serial_driver(serial_drivers, mxuport_idtable);

MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
MODULE_AUTHOR("<support@moxa.com>");
MODULE_LICENSE("GPL");