// SPDX-License-Identifier: GPL-2.0
/*
 * Prolific PL2303 USB to serial adaptor driver
 *
 * Copyright (C) 2001-2007 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2003 IBM Corp.
 *
 * Original driver for 2.2.x by anonymous
 *
 * See Documentation/usb/usb-serial.txt for more information on using this
 * driver
 */

#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/serial.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <asm/unaligned.h>
#include "pl2303.h"


#define PL2303_QUIRK_UART_STATE_IDX0            BIT(0)
#define PL2303_QUIRK_LEGACY                     BIT(1)
#define PL2303_QUIRK_ENDPOINT_HACK              BIT(2)

static const struct usb_device_id id_table[] = {
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID),
                .driver_info = PL2303_QUIRK_ENDPOINT_HACK },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ2) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_DCU11) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ3) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_CHILITAG) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_PHAROS) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_ALDIGA) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_MMX) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_GPRS) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_HCR331) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_MOTOROLA) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_ZTEK) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_TB) },
        { USB_DEVICE(IODATA_VENDOR_ID, IODATA_PRODUCT_ID) },
        { USB_DEVICE(IODATA_VENDOR_ID, IODATA_PRODUCT_ID_RSAQ5) },
        { USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_ID),
                .driver_info = PL2303_QUIRK_ENDPOINT_HACK },
        { USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_UC485),
                .driver_info = PL2303_QUIRK_ENDPOINT_HACK },
        { USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_UC232B),
                .driver_info = PL2303_QUIRK_ENDPOINT_HACK },
        { USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_ID2) },
        { USB_DEVICE(ATEN_VENDOR_ID2, ATEN_PRODUCT_ID) },
        { USB_DEVICE(ELCOM_VENDOR_ID, ELCOM_PRODUCT_ID) },
        { USB_DEVICE(ELCOM_VENDOR_ID, ELCOM_PRODUCT_ID_UCSGT) },
        { USB_DEVICE(ITEGNO_VENDOR_ID, ITEGNO_PRODUCT_ID) },
        { USB_DEVICE(ITEGNO_VENDOR_ID, ITEGNO_PRODUCT_ID_2080) },
        { USB_DEVICE(MA620_VENDOR_ID, MA620_PRODUCT_ID) },
        { USB_DEVICE(RATOC_VENDOR_ID, RATOC_PRODUCT_ID) },
        { USB_DEVICE(TRIPP_VENDOR_ID, TRIPP_PRODUCT_ID) },
        { USB_DEVICE(RADIOSHACK_VENDOR_ID, RADIOSHACK_PRODUCT_ID) },
        { USB_DEVICE(DCU10_VENDOR_ID, DCU10_PRODUCT_ID) },
        { USB_DEVICE(SITECOM_VENDOR_ID, SITECOM_PRODUCT_ID) },
        { USB_DEVICE(ALCATEL_VENDOR_ID, ALCATEL_PRODUCT_ID) },
        { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_SX1),
                .driver_info = PL2303_QUIRK_UART_STATE_IDX0 },
        { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_X65),
                .driver_info = PL2303_QUIRK_UART_STATE_IDX0 },
        { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_X75),
                .driver_info = PL2303_QUIRK_UART_STATE_IDX0 },
        { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_EF81),
                .driver_info = PL2303_QUIRK_ENDPOINT_HACK },
        { USB_DEVICE(BENQ_VENDOR_ID, BENQ_PRODUCT_ID_S81) }, /* Benq/Siemens S81 */
        { USB_DEVICE(SYNTECH_VENDOR_ID, SYNTECH_PRODUCT_ID) },
        { USB_DEVICE(NOKIA_CA42_VENDOR_ID, NOKIA_CA42_PRODUCT_ID) },
        { USB_DEVICE(CA_42_CA42_VENDOR_ID, CA_42_CA42_PRODUCT_ID) },
        { USB_DEVICE(SAGEM_VENDOR_ID, SAGEM_PRODUCT_ID) },
        { USB_DEVICE(LEADTEK_VENDOR_ID, LEADTEK_9531_PRODUCT_ID) },
        { USB_DEVICE(SPEEDDRAGON_VENDOR_ID, SPEEDDRAGON_PRODUCT_ID) },
        { USB_DEVICE(DATAPILOT_U2_VENDOR_ID, DATAPILOT_U2_PRODUCT_ID) },
        { USB_DEVICE(BELKIN_VENDOR_ID, BELKIN_PRODUCT_ID) },
        { USB_DEVICE(ALCOR_VENDOR_ID, ALCOR_PRODUCT_ID),
                .driver_info = PL2303_QUIRK_ENDPOINT_HACK },
        { USB_DEVICE(WS002IN_VENDOR_ID, WS002IN_PRODUCT_ID) },
        { USB_DEVICE(COREGA_VENDOR_ID, COREGA_PRODUCT_ID) },
        { USB_DEVICE(YCCABLE_VENDOR_ID, YCCABLE_PRODUCT_ID) },
        { USB_DEVICE(SUPERIAL_VENDOR_ID, SUPERIAL_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LD220_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LD220TA_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LD960_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LD960TA_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LCM220_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LCM960_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LM920_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_LM940_PRODUCT_ID) },
        { USB_DEVICE(HP_VENDOR_ID, HP_TD620_PRODUCT_ID) },
        { USB_DEVICE(CRESSI_VENDOR_ID, CRESSI_EDY_PRODUCT_ID) },
        { USB_DEVICE(ZEAGLE_VENDOR_ID, ZEAGLE_N2ITION3_PRODUCT_ID) },
        { USB_DEVICE(SONY_VENDOR_ID, SONY_QN3USB_PRODUCT_ID) },
        { USB_DEVICE(SANWA_VENDOR_ID, SANWA_PRODUCT_ID) },
        { USB_DEVICE(ADLINK_VENDOR_ID, ADLINK_ND6530_PRODUCT_ID) },
        { USB_DEVICE(SMART_VENDOR_ID, SMART_PRODUCT_ID) },
        { USB_DEVICE(AT_VENDOR_ID, AT_VTKIT3_PRODUCT_ID) },
        { }                                     /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table);

#define SET_LINE_REQUEST_TYPE           0x21
#define SET_LINE_REQUEST                0x20

#define SET_CONTROL_REQUEST_TYPE        0x21
#define SET_CONTROL_REQUEST             0x22
#define CONTROL_DTR                     0x01
#define CONTROL_RTS                     0x02

#define BREAK_REQUEST_TYPE              0x21
#define BREAK_REQUEST                   0x23
#define BREAK_ON                        0xffff
#define BREAK_OFF                       0x0000

#define GET_LINE_REQUEST_TYPE           0xa1
#define GET_LINE_REQUEST                0x21

#define VENDOR_WRITE_REQUEST_TYPE       0x40
#define VENDOR_WRITE_REQUEST            0x01

#define VENDOR_READ_REQUEST_TYPE        0xc0
#define VENDOR_READ_REQUEST             0x01

#define UART_STATE_INDEX                8
#define UART_STATE_MSR_MASK             0x8b
#define UART_STATE_TRANSIENT_MASK       0x74
#define UART_DCD                        0x01
#define UART_DSR                        0x02
#define UART_BREAK_ERROR                0x04
#define UART_RING                       0x08
#define UART_FRAME_ERROR                0x10
#define UART_PARITY_ERROR               0x20
#define UART_OVERRUN_ERROR              0x40
#define UART_CTS                        0x80

#define PL2303_FLOWCTRL_MASK            0xf0

static void pl2303_set_break(struct usb_serial_port *port, bool enable);

enum pl2303_type {
        TYPE_01,        /* Type 0 and 1 (difference unknown) */
        TYPE_HX,        /* HX version of the pl2303 chip */
        TYPE_COUNT
};

struct pl2303_type_data {
        speed_t max_baud_rate;
        unsigned long quirks;
        unsigned int no_autoxonxoff:1;
};

struct pl2303_serial_private {
        const struct pl2303_type_data *type;
        unsigned long quirks;
};

struct pl2303_private {
        spinlock_t lock;
        u8 line_control;
        u8 line_status;

        u8 line_settings[7];
};

static const struct pl2303_type_data pl2303_type_data[TYPE_COUNT] = {
        [TYPE_01] = {
                .max_baud_rate          = 1228800,
                .quirks                 = PL2303_QUIRK_LEGACY,
                .no_autoxonxoff         = true,
        },
        [TYPE_HX] = {
                .max_baud_rate          = 12000000,
        },
};

static int pl2303_vendor_read(struct usb_serial *serial, u16 value,
                                                        unsigned char buf[1])
{
        struct device *dev = &serial->interface->dev;
        int res;

        res = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
                        VENDOR_READ_REQUEST, VENDOR_READ_REQUEST_TYPE,
                        value, 0, buf, 1, 100);
        if (res != 1) {
                dev_err(dev, "%s - failed to read [%04x]: %d\n", __func__,
                                                                value, res);
                if (res >= 0)
                        res = -EIO;

                return res;
        }

        dev_dbg(dev, "%s - [%04x] = %02x\n", __func__, value, buf[0]);

        return 0;
}

static int pl2303_vendor_write(struct usb_serial *serial, u16 value, u16 index)
{
        struct device *dev = &serial->interface->dev;
        int res;

        dev_dbg(dev, "%s - [%04x] = %02x\n", __func__, value, index);

        res = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                        VENDOR_WRITE_REQUEST, VENDOR_WRITE_REQUEST_TYPE,
                        value, index, NULL, 0, 100);
        if (res) {
                dev_err(dev, "%s - failed to write [%04x]: %d\n", __func__,
                                                                value, res);
                return res;
        }

        return 0;
}

static int pl2303_update_reg(struct usb_serial *serial, u8 reg, u8 mask, u8 val)
{
        int ret = 0;
        u8 *buf;

        buf = kmalloc(1, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        ret = pl2303_vendor_read(serial, reg | 0x80, buf);
        if (ret)
                goto out_free;

        *buf &= ~mask;
        *buf |= val & mask;

        ret = pl2303_vendor_write(serial, reg, *buf);
out_free:
        kfree(buf);

        return ret;
}

static int pl2303_probe(struct usb_serial *serial,
                                        const struct usb_device_id *id)
{
        usb_set_serial_data(serial, (void *)id->driver_info);

        return 0;
}

/*
 * Use interrupt endpoint from first interface if available.
 *
 * This is needed due to the looney way its endpoints are set up.
 */
static int pl2303_endpoint_hack(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds)
{
        struct usb_interface *interface = serial->interface;
        struct usb_device *dev = serial->dev;
        struct device *ddev = &interface->dev;
        struct usb_host_interface *iface_desc;
        struct usb_endpoint_descriptor *endpoint;
        unsigned int i;

        if (interface == dev->actconfig->interface[0])
                return 0;

        /* check out the endpoints of the other interface */
        iface_desc = dev->actconfig->interface[0]->cur_altsetting;

        for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                endpoint = &iface_desc->endpoint[i].desc;

                if (!usb_endpoint_is_int_in(endpoint))
                        continue;

                dev_dbg(ddev, "found interrupt in on separate interface\n");
                if (epds->num_interrupt_in < ARRAY_SIZE(epds->interrupt_in))
                        epds->interrupt_in[epds->num_interrupt_in++] = endpoint;
        }

        return 0;
}

static int pl2303_calc_num_ports(struct usb_serial *serial,
                                        struct usb_serial_endpoints *epds)
{
        unsigned long quirks = (unsigned long)usb_get_serial_data(serial);
        struct device *dev = &serial->interface->dev;
        int ret;

        if (quirks & PL2303_QUIRK_ENDPOINT_HACK) {
                ret = pl2303_endpoint_hack(serial, epds);
                if (ret)
                        return ret;
        }

        if (epds->num_interrupt_in < 1) {
                dev_err(dev, "required interrupt-in endpoint missing\n");
                return -ENODEV;
        }

        return 1;
}

static int pl2303_startup(struct usb_serial *serial)
{
        struct pl2303_serial_private *spriv;
        enum pl2303_type type = TYPE_01;
        unsigned char *buf;

        spriv = kzalloc(sizeof(*spriv), GFP_KERNEL);
        if (!spriv)
                return -ENOMEM;

        buf = kmalloc(1, GFP_KERNEL);
        if (!buf) {
                kfree(spriv);
                return -ENOMEM;
        }

        if (serial->dev->descriptor.bDeviceClass == 0x02)
                type = TYPE_01;         /* type 0 */
        else if (serial->dev->descriptor.bMaxPacketSize0 == 0x40)
                type = TYPE_HX;
        else if (serial->dev->descriptor.bDeviceClass == 0x00)
                type = TYPE_01;         /* type 1 */
        else if (serial->dev->descriptor.bDeviceClass == 0xFF)
                type = TYPE_01;         /* type 1 */
        dev_dbg(&serial->interface->dev, "device type: %d\n", type);

        spriv->type = &pl2303_type_data[type];
        spriv->quirks = (unsigned long)usb_get_serial_data(serial);
        spriv->quirks |= spriv->type->quirks;

        usb_set_serial_data(serial, spriv);

        pl2303_vendor_read(serial, 0x8484, buf);
        pl2303_vendor_write(serial, 0x0404, 0);
        pl2303_vendor_read(serial, 0x8484, buf);
        pl2303_vendor_read(serial, 0x8383, buf);
        pl2303_vendor_read(serial, 0x8484, buf);
        pl2303_vendor_write(serial, 0x0404, 1);
        pl2303_vendor_read(serial, 0x8484, buf);
        pl2303_vendor_read(serial, 0x8383, buf);
        pl2303_vendor_write(serial, 0, 1);
        pl2303_vendor_write(serial, 1, 0);
        if (spriv->quirks & PL2303_QUIRK_LEGACY)
                pl2303_vendor_write(serial, 2, 0x24);
        else
                pl2303_vendor_write(serial, 2, 0x44);

        kfree(buf);

        return 0;
}

static void pl2303_release(struct usb_serial *serial)
{
        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);

        kfree(spriv);
}

static int pl2303_port_probe(struct usb_serial_port *port)
{
        struct pl2303_private *priv;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        spin_lock_init(&priv->lock);

        usb_set_serial_port_data(port, priv);

        port->port.drain_delay = 256;

        return 0;
}

static int pl2303_port_remove(struct usb_serial_port *port)
{
        struct pl2303_private *priv = usb_get_serial_port_data(port);

        kfree(priv);

        return 0;
}

static int pl2303_set_control_lines(struct usb_serial_port *port, u8 value)
{
        struct usb_device *dev = port->serial->dev;
        int retval;

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

        retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                 SET_CONTROL_REQUEST, SET_CONTROL_REQUEST_TYPE,
                                 value, 0, NULL, 0, 100);
        if (retval)
                dev_err(&port->dev, "%s - failed: %d\n", __func__, retval);

        return retval;
}

/*
 * Returns the nearest supported baud rate that can be set directly without
 * using divisors.
 */
static speed_t pl2303_get_supported_baud_rate(speed_t baud)
{
        static const speed_t baud_sup[] = {
                75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600,
                14400, 19200, 28800, 38400, 57600, 115200, 230400, 460800,
                614400, 921600, 1228800, 2457600, 3000000, 6000000
        };

        unsigned i;

        for (i = 0; i < ARRAY_SIZE(baud_sup); ++i) {
                if (baud_sup[i] > baud)
                        break;
        }

        if (i == ARRAY_SIZE(baud_sup))
                baud = baud_sup[i - 1];
        else if (i > 0 && (baud_sup[i] - baud) > (baud - baud_sup[i - 1]))
                baud = baud_sup[i - 1];
        else
                baud = baud_sup[i];

        return baud;
}

/*
 * NOTE: If unsupported baud rates are set directly, the PL2303 seems to
 *       use 9600 baud.
 */
static speed_t pl2303_encode_baud_rate_direct(unsigned char buf[4],
                                                                speed_t baud)
{
        put_unaligned_le32(baud, buf);

        return baud;
}

static speed_t pl2303_encode_baud_rate_divisor(unsigned char buf[4],
                                                                speed_t baud)
{
        unsigned int baseline, mantissa, exponent;

        /*
         * Apparently the formula is:
         *   baudrate = 12M * 32 / (mantissa * 4^exponent)
         * where
         *   mantissa = buf[8:0]
         *   exponent = buf[11:9]
         */
        baseline = 12000000 * 32;
        mantissa = baseline / baud;
        if (mantissa == 0)
                mantissa = 1;   /* Avoid dividing by zero if baud > 32*12M. */
        exponent = 0;
        while (mantissa >= 512) {
                if (exponent < 7) {
                        mantissa >>= 2; /* divide by 4 */
                        exponent++;
                } else {
                        /* Exponent is maxed. Trim mantissa and leave. */
                        mantissa = 511;
                        break;
                }
        }

        buf[3] = 0x80;
        buf[2] = 0;
        buf[1] = exponent << 1 | mantissa >> 8;
        buf[0] = mantissa & 0xff;

        /* Calculate and return the exact baud rate. */
        baud = (baseline / mantissa) >> (exponent << 1);

        return baud;
}

static void pl2303_encode_baud_rate(struct tty_struct *tty,
                                        struct usb_serial_port *port,
                                        u8 buf[4])
{
        struct usb_serial *serial = port->serial;
        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
        speed_t baud_sup;
        speed_t baud;

        baud = tty_get_baud_rate(tty);
        dev_dbg(&port->dev, "baud requested = %u\n", baud);
        if (!baud)
                return;

        if (spriv->type->max_baud_rate)
                baud = min_t(speed_t, baud, spriv->type->max_baud_rate);
        /*
         * Use direct method for supported baud rates, otherwise use divisors.
         */
        baud_sup = pl2303_get_supported_baud_rate(baud);

        if (baud == baud_sup)
                baud = pl2303_encode_baud_rate_direct(buf, baud);
        else
                baud = pl2303_encode_baud_rate_divisor(buf, baud);

        /* Save resulting baud rate */
        tty_encode_baud_rate(tty, baud, baud);
        dev_dbg(&port->dev, "baud set = %u\n", baud);
}

static int pl2303_get_line_request(struct usb_serial_port *port,
                                                        unsigned char buf[7])
{
        struct usb_device *udev = port->serial->dev;
        int ret;

        ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
                                GET_LINE_REQUEST, GET_LINE_REQUEST_TYPE,
                                0, 0, buf, 7, 100);
        if (ret != 7) {
                dev_err(&port->dev, "%s - failed: %d\n", __func__, ret);

                if (ret >= 0)
                        ret = -EIO;

                return ret;
        }

        dev_dbg(&port->dev, "%s - %7ph\n", __func__, buf);

        return 0;
}

static int pl2303_set_line_request(struct usb_serial_port *port,
                                                        unsigned char buf[7])
{
        struct usb_device *udev = port->serial->dev;
        int ret;

        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                SET_LINE_REQUEST, SET_LINE_REQUEST_TYPE,
                                0, 0, buf, 7, 100);
        if (ret < 0) {
                dev_err(&port->dev, "%s - failed: %d\n", __func__, ret);
                return ret;
        }

        dev_dbg(&port->dev, "%s - %7ph\n", __func__, buf);

        return 0;
}

static bool pl2303_termios_change(const struct ktermios *a, const struct ktermios *b)
{
        bool ixon_change;

        ixon_change = ((a->c_iflag ^ b->c_iflag) & (IXON | IXANY)) ||
                        a->c_cc[VSTART] != b->c_cc[VSTART] ||
                        a->c_cc[VSTOP] != b->c_cc[VSTOP];

        return tty_termios_hw_change(a, b) || ixon_change;
}

static bool pl2303_enable_xonxoff(struct tty_struct *tty, const struct pl2303_type_data *type)
{
        if (!I_IXON(tty) || I_IXANY(tty))
                return false;

        if (START_CHAR(tty) != 0x11 || STOP_CHAR(tty) != 0x13)
                return false;

        if (type->no_autoxonxoff)
                return false;

        return true;
}

static void pl2303_set_termios(struct tty_struct *tty,
                struct usb_serial_port *port, struct ktermios *old_termios)
{
        struct usb_serial *serial = port->serial;
        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
        struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned char *buf;
        int ret;
        u8 control;

        if (old_termios && !pl2303_termios_change(&tty->termios, old_termios))
                return;

        buf = kzalloc(7, GFP_KERNEL);
        if (!buf) {
                /* Report back no change occurred */
                if (old_termios)
                        tty->termios = *old_termios;
                return;
        }

        pl2303_get_line_request(port, buf);

        switch (C_CSIZE(tty)) {
        case CS5:
                buf[6] = 5;
                break;
        case CS6:
                buf[6] = 6;
                break;
        case CS7:
                buf[6] = 7;
                break;
        default:
        case CS8:
                buf[6] = 8;
        }
        dev_dbg(&port->dev, "data bits = %d\n", buf[6]);

        /* For reference buf[0]:buf[3] baud rate value */
        pl2303_encode_baud_rate(tty, port, &buf[0]);

        /* For reference buf[4]=0 is 1 stop bits */
        /* For reference buf[4]=1 is 1.5 stop bits */
        /* For reference buf[4]=2 is 2 stop bits */
        if (C_CSTOPB(tty)) {
                /*
                 * NOTE: Comply with "real" UARTs / RS232:
                 *       use 1.5 instead of 2 stop bits with 5 data bits
                 */
                if (C_CSIZE(tty) == CS5) {
                        buf[4] = 1;
                        dev_dbg(&port->dev, "stop bits = 1.5\n");
                } else {
                        buf[4] = 2;
                        dev_dbg(&port->dev, "stop bits = 2\n");
                }
        } else {
                buf[4] = 0;
                dev_dbg(&port->dev, "stop bits = 1\n");
        }

        if (C_PARENB(tty)) {
                /* For reference buf[5]=0 is none parity */
                /* For reference buf[5]=1 is odd parity */
                /* For reference buf[5]=2 is even parity */
                /* For reference buf[5]=3 is mark parity */
                /* For reference buf[5]=4 is space parity */
                if (C_PARODD(tty)) {
                        if (C_CMSPAR(tty)) {
                                buf[5] = 3;
                                dev_dbg(&port->dev, "parity = mark\n");
                        } else {
                                buf[5] = 1;
                                dev_dbg(&port->dev, "parity = odd\n");
                        }
                } else {
                        if (C_CMSPAR(tty)) {
                                buf[5] = 4;
                                dev_dbg(&port->dev, "parity = space\n");
                        } else {
                                buf[5] = 2;
                                dev_dbg(&port->dev, "parity = even\n");
                        }
                }
        } else {
                buf[5] = 0;
                dev_dbg(&port->dev, "parity = none\n");
        }

        /*
         * Some PL2303 are known to lose bytes if you change serial settings
         * even to the same values as before. Thus we actually need to filter
         * in this specific case.
         *
         * Note that the tty_termios_hw_change check above is not sufficient
         * as a previously requested baud rate may differ from the one
         * actually used (and stored in old_termios).
         *
         * NOTE: No additional locking needed for line_settings as it is
         *       only used in set_termios, which is serialised against itself.
         */
        if (!old_termios || memcmp(buf, priv->line_settings, 7)) {
                ret = pl2303_set_line_request(port, buf);
                if (!ret)
                        memcpy(priv->line_settings, buf, 7);
        }

        /* change control lines if we are switching to or from B0 */
        spin_lock_irqsave(&priv->lock, flags);
        control = priv->line_control;
        if (C_BAUD(tty) == B0)
                priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
        else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
                priv->line_control |= (CONTROL_DTR | CONTROL_RTS);
        if (control != priv->line_control) {
                control = priv->line_control;
                spin_unlock_irqrestore(&priv->lock, flags);
                pl2303_set_control_lines(port, control);
        } else {
                spin_unlock_irqrestore(&priv->lock, flags);
        }

        if (C_CRTSCTS(tty)) {
                if (spriv->quirks & PL2303_QUIRK_LEGACY)
                        pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0x40);
                else
                        pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0x60);
        } else if (pl2303_enable_xonxoff(tty, spriv->type)) {
                pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0xc0);
        } else {
                pl2303_update_reg(serial, 0, PL2303_FLOWCTRL_MASK, 0);
        }

        kfree(buf);
}

static void pl2303_dtr_rts(struct usb_serial_port *port, int on)
{
        struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        u8 control;

        spin_lock_irqsave(&priv->lock, flags);
        if (on)
                priv->line_control |= (CONTROL_DTR | CONTROL_RTS);
        else
                priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
        control = priv->line_control;
        spin_unlock_irqrestore(&priv->lock, flags);

        pl2303_set_control_lines(port, control);
}

static void pl2303_close(struct usb_serial_port *port)
{
        usb_serial_generic_close(port);
        usb_kill_urb(port->interrupt_in_urb);
        pl2303_set_break(port, false);
}

static int pl2303_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct usb_serial *serial = port->serial;
        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
        int result;

        if (spriv->quirks & PL2303_QUIRK_LEGACY) {
                usb_clear_halt(serial->dev, port->write_urb->pipe);
                usb_clear_halt(serial->dev, port->read_urb->pipe);
        } else {
                /* reset upstream data pipes */
                pl2303_vendor_write(serial, 8, 0);
                pl2303_vendor_write(serial, 9, 0);
        }

        /* Setup termios */
        if (tty)
                pl2303_set_termios(tty, port, NULL);

        result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
        if (result) {
                dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
                        result);
                return result;
        }

        result = usb_serial_generic_open(tty, port);
        if (result) {
                usb_kill_urb(port->interrupt_in_urb);
                return result;
        }

        return 0;
}

static int pl2303_tiocmset(struct tty_struct *tty,
                           unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        u8 control;
        int ret;

        spin_lock_irqsave(&priv->lock, flags);
        if (set & TIOCM_RTS)
                priv->line_control |= CONTROL_RTS;
        if (set & TIOCM_DTR)
                priv->line_control |= CONTROL_DTR;
        if (clear & TIOCM_RTS)
                priv->line_control &= ~CONTROL_RTS;
        if (clear & TIOCM_DTR)
                priv->line_control &= ~CONTROL_DTR;
        control = priv->line_control;
        spin_unlock_irqrestore(&priv->lock, flags);

        ret = pl2303_set_control_lines(port, control);
        if (ret)
                return usb_translate_errors(ret);

        return 0;
}

static int pl2303_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int mcr;
        unsigned int status;
        unsigned int result;

        spin_lock_irqsave(&priv->lock, flags);
        mcr = priv->line_control;
        status = priv->line_status;
        spin_unlock_irqrestore(&priv->lock, flags);

        result = ((mcr & CONTROL_DTR)           ? TIOCM_DTR : 0)
                  | ((mcr & CONTROL_RTS)        ? TIOCM_RTS : 0)
                  | ((status & UART_CTS)        ? TIOCM_CTS : 0)
                  | ((status & UART_DSR)        ? TIOCM_DSR : 0)
                  | ((status & UART_RING)       ? TIOCM_RI  : 0)
                  | ((status & UART_DCD)        ? TIOCM_CD  : 0);

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

        return result;
}

static int pl2303_carrier_raised(struct usb_serial_port *port)
{
        struct pl2303_private *priv = usb_get_serial_port_data(port);

        if (priv->line_status & UART_DCD)
                return 1;

        return 0;
}

static int pl2303_get_serial(struct tty_struct *tty,
                        struct serial_struct *ss)
{
        struct usb_serial_port *port = tty->driver_data;

        ss->type = PORT_16654;
        ss->line = port->minor;
        ss->port = port->port_number;
        ss->baud_base = 460800;
        return 0;
}

static void pl2303_set_break(struct usb_serial_port *port, bool enable)
{
        struct usb_serial *serial = port->serial;
        u16 state;
        int result;

        if (enable)
                state = BREAK_ON;
        else
                state = BREAK_OFF;

        dev_dbg(&port->dev, "%s - turning break %s\n", __func__,
                        state == BREAK_OFF ? "off" : "on");

        result = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
                                 BREAK_REQUEST, BREAK_REQUEST_TYPE, state,
                                 0, NULL, 0, 100);
        if (result)
                dev_err(&port->dev, "error sending break = %d\n", result);
}

static void pl2303_break_ctl(struct tty_struct *tty, int state)
{
        struct usb_serial_port *port = tty->driver_data;

        pl2303_set_break(port, state);
}

static void pl2303_update_line_status(struct usb_serial_port *port,
                                      unsigned char *data,
                                      unsigned int actual_length)
{
        struct usb_serial *serial = port->serial;
        struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
        struct pl2303_private *priv = usb_get_serial_port_data(port);
        struct tty_struct *tty;
        unsigned long flags;
        unsigned int status_idx = UART_STATE_INDEX;
        u8 status;
        u8 delta;

        if (spriv->quirks & PL2303_QUIRK_UART_STATE_IDX0)
                status_idx = 0;

        if (actual_length < status_idx + 1)
                return;

        status = data[status_idx];

        /* Save off the uart status for others to look at */
        spin_lock_irqsave(&priv->lock, flags);
        delta = priv->line_status ^ status;
        priv->line_status = status;
        spin_unlock_irqrestore(&priv->lock, flags);

        if (status & UART_BREAK_ERROR)
                usb_serial_handle_break(port);

        if (delta & UART_STATE_MSR_MASK) {
                if (delta & UART_CTS)
                        port->icount.cts++;
                if (delta & UART_DSR)
                        port->icount.dsr++;
                if (delta & UART_RING)
                        port->icount.rng++;
                if (delta & UART_DCD) {
                        port->icount.dcd++;
                        tty = tty_port_tty_get(&port->port);
                        if (tty) {
                                usb_serial_handle_dcd_change(port, tty,
                                                        status & UART_DCD);
                                tty_kref_put(tty);
                        }
                }

                wake_up_interruptible(&port->port.delta_msr_wait);
        }
}

static void pl2303_read_int_callback(struct urb *urb)
{
        struct usb_serial_port *port =  urb->context;
        unsigned char *data = urb->transfer_buffer;
        unsigned int actual_length = urb->actual_length;
        int status = urb->status;
        int retval;

        switch (status) {
        case 0:
                /* success */
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                /* this urb is terminated, clean up */
                dev_dbg(&port->dev, "%s - urb shutting down with status: %d\n",
                        __func__, status);
                return;
        default:
                dev_dbg(&port->dev, "%s - nonzero urb status received: %d\n",
                        __func__, status);
                goto exit;
        }

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

        pl2303_update_line_status(port, data, actual_length);

exit:
        retval = usb_submit_urb(urb, GFP_ATOMIC);
        if (retval) {
                dev_err(&port->dev,
                        "%s - usb_submit_urb failed with result %d\n",
                        __func__, retval);
        }
}

static void pl2303_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned char *data = urb->transfer_buffer;
        char tty_flag = TTY_NORMAL;
        unsigned long flags;
        u8 line_status;
        int i;

        /* update line status */
        spin_lock_irqsave(&priv->lock, flags);
        line_status = priv->line_status;

        priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
        spin_unlock_irqrestore(&priv->lock, flags);

        if (!urb->actual_length)
                return;

        /*
         * Break takes precedence over parity, which takes precedence over
         * framing errors.
         */
        if (line_status & UART_BREAK_ERROR)
                tty_flag = TTY_BREAK;
        else if (line_status & UART_PARITY_ERROR)
                tty_flag = TTY_PARITY;
        else if (line_status & UART_FRAME_ERROR)
                tty_flag = TTY_FRAME;

        if (tty_flag != TTY_NORMAL)
                dev_dbg(&port->dev, "%s - tty_flag = %d\n", __func__,
                                                                tty_flag);
        /* overrun is special, not associated with a char */
        if (line_status & UART_OVERRUN_ERROR)
                tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);

        if (port->port.console && port->sysrq) {
                for (i = 0; i < urb->actual_length; ++i)
                        if (!usb_serial_handle_sysrq_char(port, data[i]))
                                tty_insert_flip_char(&port->port, data[i],
                                                tty_flag);
        } else {
                tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag,
                                                        urb->actual_length);
        }

        tty_flip_buffer_push(&port->port);
}

static struct usb_serial_driver pl2303_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "pl2303",
        },
        .id_table =             id_table,
        .num_bulk_in =          1,
        .num_bulk_out =         1,
        .num_interrupt_in =     0,      /* see pl2303_calc_num_ports */
        .bulk_in_size =         256,
        .bulk_out_size =        256,
        .open =                 pl2303_open,
        .close =                pl2303_close,
        .dtr_rts =              pl2303_dtr_rts,
        .carrier_raised =       pl2303_carrier_raised,
        .get_serial =           pl2303_get_serial,
        .break_ctl =            pl2303_break_ctl,
        .set_termios =          pl2303_set_termios,
        .tiocmget =             pl2303_tiocmget,
        .tiocmset =             pl2303_tiocmset,
        .tiocmiwait =           usb_serial_generic_tiocmiwait,
        .process_read_urb =     pl2303_process_read_urb,
        .read_int_callback =    pl2303_read_int_callback,
        .probe =                pl2303_probe,
        .calc_num_ports =       pl2303_calc_num_ports,
        .attach =               pl2303_startup,
        .release =              pl2303_release,
        .port_probe =           pl2303_port_probe,
        .port_remove =          pl2303_port_remove,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &pl2303_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION("Prolific PL2303 USB to serial adaptor driver");
MODULE_LICENSE("GPL v2");