// SPDX-License-Identifier: GPL-2.0+
/*
 * Belkin USB Serial Adapter Driver
 *
 *  Copyright (C) 2000          William Greathouse (wgreathouse@smva.com)
 *  Copyright (C) 2000-2001     Greg Kroah-Hartman (greg@kroah.com)
 *  Copyright (C) 2010          Johan Hovold (jhovold@gmail.com)
 *
 *  This program is largely derived from work by the linux-usb group
 *  and associated source files.  Please see the usb/serial files for
 *  individual credits and copyrights.
 *
 * See Documentation/usb/usb-serial.rst for more information on using this
 * driver
 *
 * TODO:
 * -- Add true modem control line query capability.  Currently we track the
 *    states reported by the interrupt and the states we request.
 * -- Add support for flush commands
 */

#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/spinlock.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include "belkin_sa.h"

#define DRIVER_AUTHOR "William Greathouse <wgreathouse@smva.com>"
#define DRIVER_DESC "USB Belkin Serial converter driver"

/* function prototypes for a Belkin USB Serial Adapter F5U103 */
static int belkin_sa_port_probe(struct usb_serial_port *port);
static void belkin_sa_port_remove(struct usb_serial_port *port);
static int  belkin_sa_open(struct tty_struct *tty,
                        struct usb_serial_port *port);
static void belkin_sa_close(struct usb_serial_port *port);
static void belkin_sa_read_int_callback(struct urb *urb);
static void belkin_sa_process_read_urb(struct urb *urb);
static void belkin_sa_set_termios(struct tty_struct *tty,
                                  struct usb_serial_port *port,
                                  const struct ktermios *old_termios);
static int belkin_sa_break_ctl(struct tty_struct *tty, int break_state);
static int  belkin_sa_tiocmget(struct tty_struct *tty);
static int  belkin_sa_tiocmset(struct tty_struct *tty,
                                        unsigned int set, unsigned int clear);


static const struct usb_device_id id_table[] = {
        { USB_DEVICE(BELKIN_SA_VID, BELKIN_SA_PID) },
        { USB_DEVICE(BELKIN_OLD_VID, BELKIN_OLD_PID) },
        { USB_DEVICE(PERACOM_VID, PERACOM_PID) },
        { USB_DEVICE(GOHUBS_VID, GOHUBS_PID) },
        { USB_DEVICE(GOHUBS_VID, HANDYLINK_PID) },
        { USB_DEVICE(BELKIN_DOCKSTATION_VID, BELKIN_DOCKSTATION_PID) },
        { }     /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, id_table);

/* All of the device info needed for the serial converters */
static struct usb_serial_driver belkin_device = {
        .driver = {
                .name =         "belkin",
        },
        .description =          "Belkin / Peracom / GoHubs USB Serial Adapter",
        .id_table =             id_table,
        .num_ports =            1,
        .open =                 belkin_sa_open,
        .close =                belkin_sa_close,
        .read_int_callback =    belkin_sa_read_int_callback,
        .process_read_urb =     belkin_sa_process_read_urb,
        .set_termios =          belkin_sa_set_termios,
        .break_ctl =            belkin_sa_break_ctl,
        .tiocmget =             belkin_sa_tiocmget,
        .tiocmset =             belkin_sa_tiocmset,
        .port_probe =           belkin_sa_port_probe,
        .port_remove =          belkin_sa_port_remove,
};

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

struct belkin_sa_private {
        spinlock_t              lock;
        unsigned long           control_state;
        unsigned char           last_lsr;
        unsigned char           last_msr;
        int                     bad_flow_control;
};


/*
 * ***************************************************************************
 * Belkin USB Serial Adapter F5U103 specific driver functions
 * ***************************************************************************
 */

#define WDR_TIMEOUT 5000 /* default urb timeout */

/* assumes that struct usb_serial *serial is available */
#define BSA_USB_CMD(c, v) usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), \
                                            (c), BELKIN_SA_SET_REQUEST_TYPE, \
                                            (v), 0, NULL, 0, WDR_TIMEOUT)

static int belkin_sa_port_probe(struct usb_serial_port *port)
{
        struct usb_device *dev = port->serial->dev;
        struct belkin_sa_private *priv;

        priv = kmalloc_obj(struct belkin_sa_private);
        if (!priv)
                return -ENOMEM;

        spin_lock_init(&priv->lock);
        priv->control_state = 0;
        priv->last_lsr = 0;
        priv->last_msr = 0;
        /* see comments at top of file */
        priv->bad_flow_control =
                (le16_to_cpu(dev->descriptor.bcdDevice) <= 0x0206) ? 1 : 0;
        dev_info(&dev->dev, "bcdDevice: %04x, bfc: %d\n",
                                        le16_to_cpu(dev->descriptor.bcdDevice),
                                        priv->bad_flow_control);

        usb_set_serial_port_data(port, priv);

        return 0;
}

static void belkin_sa_port_remove(struct usb_serial_port *port)
{
        struct belkin_sa_private *priv;

        priv = usb_get_serial_port_data(port);
        kfree(priv);
}

static int belkin_sa_open(struct tty_struct *tty,
                                        struct usb_serial_port *port)
{
        int retval;

        retval = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
        if (retval) {
                dev_err(&port->dev, "usb_submit_urb(read int) failed\n");
                return retval;
        }

        retval = usb_serial_generic_open(tty, port);
        if (retval)
                usb_kill_urb(port->interrupt_in_urb);

        return retval;
}

static void belkin_sa_close(struct usb_serial_port *port)
{
        usb_serial_generic_close(port);
        usb_kill_urb(port->interrupt_in_urb);
}

static void belkin_sa_read_int_callback(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct belkin_sa_private *priv;
        unsigned char *data = urb->transfer_buffer;
        int retval;
        int status = urb->status;
        unsigned long flags;

        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, data);

        /* Handle known interrupt data */
        /* ignore data[0] and data[1] */

        priv = usb_get_serial_port_data(port);
        spin_lock_irqsave(&priv->lock, flags);
        priv->last_msr = data[BELKIN_SA_MSR_INDEX];

        /* Record Control Line states */
        if (priv->last_msr & BELKIN_SA_MSR_DSR)
                priv->control_state |= TIOCM_DSR;
        else
                priv->control_state &= ~TIOCM_DSR;

        if (priv->last_msr & BELKIN_SA_MSR_CTS)
                priv->control_state |= TIOCM_CTS;
        else
                priv->control_state &= ~TIOCM_CTS;

        if (priv->last_msr & BELKIN_SA_MSR_RI)
                priv->control_state |= TIOCM_RI;
        else
                priv->control_state &= ~TIOCM_RI;

        if (priv->last_msr & BELKIN_SA_MSR_CD)
                priv->control_state |= TIOCM_CD;
        else
                priv->control_state &= ~TIOCM_CD;

        priv->last_lsr = data[BELKIN_SA_LSR_INDEX];
        spin_unlock_irqrestore(&priv->lock, flags);
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 belkin_sa_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        struct belkin_sa_private *priv = usb_get_serial_port_data(port);
        unsigned char *data = urb->transfer_buffer;
        unsigned long flags;
        unsigned char status;
        char tty_flag;

        /* Update line status */
        tty_flag = TTY_NORMAL;

        spin_lock_irqsave(&priv->lock, flags);
        status = priv->last_lsr;
        priv->last_lsr &= ~BELKIN_SA_LSR_ERR;
        spin_unlock_irqrestore(&priv->lock, flags);

        if (!urb->actual_length)
                return;

        if (status & BELKIN_SA_LSR_ERR) {
                /* Break takes precedence over parity, which takes precedence
                 * over framing errors. */
                if (status & BELKIN_SA_LSR_BI)
                        tty_flag = TTY_BREAK;
                else if (status & BELKIN_SA_LSR_PE)
                        tty_flag = TTY_PARITY;
                else if (status & BELKIN_SA_LSR_FE)
                        tty_flag = TTY_FRAME;
                dev_dbg(&port->dev, "tty_flag = %d\n", tty_flag);

                /* Overrun is special, not associated with a char. */
                if (status & BELKIN_SA_LSR_OE)
                        tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
        }

        tty_insert_flip_string_fixed_flag(&port->port, data, tty_flag,
                                                        urb->actual_length);
        tty_flip_buffer_push(&port->port);
}

static void belkin_sa_set_termios(struct tty_struct *tty,
                                  struct usb_serial_port *port,
                                  const struct ktermios *old_termios)
{
        struct usb_serial *serial = port->serial;
        struct belkin_sa_private *priv = usb_get_serial_port_data(port);
        unsigned int iflag;
        unsigned int cflag;
        unsigned int old_iflag = 0;
        unsigned int old_cflag = 0;
        __u16 urb_value = 0; /* Will hold the new flags */
        unsigned long flags;
        unsigned long control_state;
        int bad_flow_control;
        speed_t baud;
        struct ktermios *termios = &tty->termios;

        iflag = termios->c_iflag;
        cflag = termios->c_cflag;

        termios->c_cflag &= ~CMSPAR;

        /* get a local copy of the current port settings */
        spin_lock_irqsave(&priv->lock, flags);
        control_state = priv->control_state;
        bad_flow_control = priv->bad_flow_control;
        spin_unlock_irqrestore(&priv->lock, flags);

        old_iflag = old_termios->c_iflag;
        old_cflag = old_termios->c_cflag;

        /* Set the baud rate */
        if ((cflag & CBAUD) != (old_cflag & CBAUD)) {
                /* reassert DTR and (maybe) RTS on transition from B0 */
                if ((old_cflag & CBAUD) == B0) {
                        control_state |= (TIOCM_DTR|TIOCM_RTS);
                        if (BSA_USB_CMD(BELKIN_SA_SET_DTR_REQUEST, 1) < 0)
                                dev_err(&port->dev, "Set DTR error\n");
                        /* don't set RTS if using hardware flow control */
                        if (!(old_cflag & CRTSCTS))
                                if (BSA_USB_CMD(BELKIN_SA_SET_RTS_REQUEST
                                                                , 1) < 0)
                                        dev_err(&port->dev, "Set RTS error\n");
                }
        }

        baud = tty_get_baud_rate(tty);
        if (baud) {
                urb_value = BELKIN_SA_BAUD(baud);
                /* Clip to maximum speed */
                if (urb_value == 0)
                        urb_value = 1;
                /* Turn it back into a resulting real baud rate */
                baud = BELKIN_SA_BAUD(urb_value);

                /* Report the actual baud rate back to the caller */
                tty_encode_baud_rate(tty, baud, baud);
                if (BSA_USB_CMD(BELKIN_SA_SET_BAUDRATE_REQUEST, urb_value) < 0)
                        dev_err(&port->dev, "Set baudrate error\n");
        } else {
                /* Disable flow control */
                if (BSA_USB_CMD(BELKIN_SA_SET_FLOW_CTRL_REQUEST,
                                                BELKIN_SA_FLOW_NONE) < 0)
                        dev_err(&port->dev, "Disable flowcontrol error\n");
                /* Drop RTS and DTR */
                control_state &= ~(TIOCM_DTR | TIOCM_RTS);
                if (BSA_USB_CMD(BELKIN_SA_SET_DTR_REQUEST, 0) < 0)
                        dev_err(&port->dev, "DTR LOW error\n");
                if (BSA_USB_CMD(BELKIN_SA_SET_RTS_REQUEST, 0) < 0)
                        dev_err(&port->dev, "RTS LOW error\n");
        }

        /* set the parity */
        if ((cflag ^ old_cflag) & (PARENB | PARODD)) {
                if (cflag & PARENB)
                        urb_value = (cflag & PARODD) ?  BELKIN_SA_PARITY_ODD
                                                : BELKIN_SA_PARITY_EVEN;
                else
                        urb_value = BELKIN_SA_PARITY_NONE;
                if (BSA_USB_CMD(BELKIN_SA_SET_PARITY_REQUEST, urb_value) < 0)
                        dev_err(&port->dev, "Set parity error\n");
        }

        /* set the number of data bits */
        if ((cflag & CSIZE) != (old_cflag & CSIZE)) {
                urb_value = BELKIN_SA_DATA_BITS(tty_get_char_size(cflag));
                if (BSA_USB_CMD(BELKIN_SA_SET_DATA_BITS_REQUEST, urb_value) < 0)
                        dev_err(&port->dev, "Set data bits error\n");
        }

        /* set the number of stop bits */
        if ((cflag & CSTOPB) != (old_cflag & CSTOPB)) {
                urb_value = (cflag & CSTOPB) ? BELKIN_SA_STOP_BITS(2)
                                                : BELKIN_SA_STOP_BITS(1);
                if (BSA_USB_CMD(BELKIN_SA_SET_STOP_BITS_REQUEST,
                                                        urb_value) < 0)
                        dev_err(&port->dev, "Set stop bits error\n");
        }

        /* Set flow control */
        if (((iflag ^ old_iflag) & (IXOFF | IXON)) ||
                ((cflag ^ old_cflag) & CRTSCTS)) {
                urb_value = 0;
                if ((iflag & IXOFF) || (iflag & IXON))
                        urb_value |= (BELKIN_SA_FLOW_OXON | BELKIN_SA_FLOW_IXON);
                else
                        urb_value &= ~(BELKIN_SA_FLOW_OXON | BELKIN_SA_FLOW_IXON);

                if (cflag & CRTSCTS)
                        urb_value |=  (BELKIN_SA_FLOW_OCTS | BELKIN_SA_FLOW_IRTS);
                else
                        urb_value &= ~(BELKIN_SA_FLOW_OCTS | BELKIN_SA_FLOW_IRTS);

                if (bad_flow_control)
                        urb_value &= ~(BELKIN_SA_FLOW_IRTS);

                if (BSA_USB_CMD(BELKIN_SA_SET_FLOW_CTRL_REQUEST, urb_value) < 0)
                        dev_err(&port->dev, "Set flow control error\n");
        }

        /* save off the modified port settings */
        spin_lock_irqsave(&priv->lock, flags);
        priv->control_state = control_state;
        spin_unlock_irqrestore(&priv->lock, flags);
}

static int belkin_sa_break_ctl(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;
        int ret;

        ret = BSA_USB_CMD(BELKIN_SA_SET_BREAK_REQUEST, break_state ? 1 : 0);
        if (ret < 0) {
                dev_err(&port->dev, "Set break_ctl %d\n", break_state);
                return ret;
        }

        return 0;
}

static int belkin_sa_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct belkin_sa_private *priv = usb_get_serial_port_data(port);
        unsigned long control_state;
        unsigned long flags;

        spin_lock_irqsave(&priv->lock, flags);
        control_state = priv->control_state;
        spin_unlock_irqrestore(&priv->lock, flags);

        return control_state;
}

static int belkin_sa_tiocmset(struct tty_struct *tty,
                               unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_serial *serial = port->serial;
        struct belkin_sa_private *priv = usb_get_serial_port_data(port);
        unsigned long control_state;
        unsigned long flags;
        int retval = 0;

        spin_lock_irqsave(&priv->lock, flags);
        control_state = priv->control_state;

        if (set & TIOCM_RTS)
                control_state |= TIOCM_RTS;
        if (set & TIOCM_DTR)
                control_state |= TIOCM_DTR;
        if (clear & TIOCM_RTS)
                control_state &= ~TIOCM_RTS;
        if (clear & TIOCM_DTR)
                control_state &= ~TIOCM_DTR;

        priv->control_state = control_state;
        spin_unlock_irqrestore(&priv->lock, flags);

        if ((set | clear) & TIOCM_RTS) {
                retval = BSA_USB_CMD(BELKIN_SA_SET_RTS_REQUEST,
                                        !!(control_state & TIOCM_RTS));
                if (retval < 0) {
                        dev_err(&port->dev, "Set RTS error %d\n", retval);
                        goto exit;
                }
        }

        if ((set | clear) & TIOCM_DTR) {
                retval = BSA_USB_CMD(BELKIN_SA_SET_DTR_REQUEST,
                                        !!(control_state & TIOCM_DTR));
                if (retval < 0) {
                        dev_err(&port->dev, "Set DTR error %d\n", retval);
                        goto exit;
                }
        }
exit:
        return retval;
}

module_usb_serial_driver(serial_drivers, id_table);

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