// SPDX-License-Identifier: GPL-2.0
/*
 * usb-serial driver for Quatech SSU-100
 *
 * based on ftdi_sio.c and the original serqt_usb.c from Quatech
 *
 */

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/serial_reg.h>

#define QT_OPEN_CLOSE_CHANNEL       0xca
#define QT_SET_GET_DEVICE           0xc2
#define QT_SET_GET_REGISTER         0xc0
#define QT_GET_SET_PREBUF_TRIG_LVL  0xcc
#define QT_SET_ATF                  0xcd
#define QT_GET_SET_UART             0xc1
#define QT_TRANSFER_IN              0xc0
#define QT_HW_FLOW_CONTROL_MASK     0xc5
#define QT_SW_FLOW_CONTROL_MASK     0xc6

#define  SERIAL_MSR_MASK            0xf0

#define  SERIAL_CRTSCTS ((UART_MCR_RTS << 8) | UART_MSR_CTS)

#define  SERIAL_EVEN_PARITY         (UART_LCR_PARITY | UART_LCR_EPAR)

#define  MAX_BAUD_RATE              460800

#define ATC_DISABLED                0x00
#define DUPMODE_BITS        0xc0
#define RR_BITS             0x03
#define LOOPMODE_BITS       0x41
#define RS232_MODE          0x00
#define RTSCTS_TO_CONNECTOR 0x40
#define CLKS_X4             0x02
#define FULLPWRBIT          0x00000080
#define NEXT_BOARD_POWER_BIT        0x00000004

#define DRIVER_DESC "Quatech SSU-100 USB to Serial Driver"

#define USB_VENDOR_ID_QUATECH   0x061d  /* Quatech VID */
#define QUATECH_SSU100  0xC020  /* SSU100 */

static const struct usb_device_id id_table[] = {
        {USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_SSU100)},
        {}                      /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, id_table);

struct ssu100_port_private {
        spinlock_t status_lock;
        u8 shadowLSR;
        u8 shadowMSR;
};

static inline int ssu100_control_msg(struct usb_device *dev,
                                     u8 request, u16 data, u16 index)
{
        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                               request, 0x40, data, index,
                               NULL, 0, 300);
}

static inline int ssu100_setdevice(struct usb_device *dev, u8 *data)
{
        u16 x = ((u16)(data[1] << 8) | (u16)(data[0]));

        return ssu100_control_msg(dev, QT_SET_GET_DEVICE, x, 0);
}


static inline int ssu100_getdevice(struct usb_device *dev, u8 *data)
{
        int ret;

        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                              QT_SET_GET_DEVICE, 0xc0, 0, 0,
                              data, 3, 300);
        if (ret < 3) {
                if (ret >= 0)
                        ret = -EIO;
        }

        return ret;
}

static inline int ssu100_getregister(struct usb_device *dev,
                                     unsigned short uart,
                                     unsigned short reg,
                                     u8 *data)
{
        int ret;

        ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                              QT_SET_GET_REGISTER, 0xc0, reg,
                              uart, data, sizeof(*data), 300);
        if (ret < (int)sizeof(*data)) {
                if (ret >= 0)
                        ret = -EIO;
        }

        return ret;
}


static inline int ssu100_setregister(struct usb_device *dev,
                                     unsigned short uart,
                                     unsigned short reg,
                                     u16 data)
{
        u16 value = (data << 8) | reg;

        return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                               QT_SET_GET_REGISTER, 0x40, value, uart,
                               NULL, 0, 300);

}

#define set_mctrl(dev, set)             update_mctrl((dev), (set), 0)
#define clear_mctrl(dev, clear) update_mctrl((dev), 0, (clear))

/* these do not deal with device that have more than 1 port */
static inline int update_mctrl(struct usb_device *dev, unsigned int set,
                               unsigned int clear)
{
        unsigned urb_value;
        int result;

        if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
                dev_dbg(&dev->dev, "%s - DTR|RTS not being set|cleared\n", __func__);
                return 0;       /* no change */
        }

        clear &= ~set;  /* 'set' takes precedence over 'clear' */
        urb_value = 0;
        if (set & TIOCM_DTR)
                urb_value |= UART_MCR_DTR;
        if (set & TIOCM_RTS)
                urb_value |= UART_MCR_RTS;

        result = ssu100_setregister(dev, 0, UART_MCR, urb_value);
        if (result < 0)
                dev_dbg(&dev->dev, "%s Error from MODEM_CTRL urb\n", __func__);

        return result;
}

static int ssu100_initdevice(struct usb_device *dev)
{
        u8 *data;
        int result = 0;

        data = kzalloc(3, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        result = ssu100_getdevice(dev, data);
        if (result < 0) {
                dev_dbg(&dev->dev, "%s - get_device failed %i\n", __func__, result);
                goto out;
        }

        data[1] &= ~FULLPWRBIT;

        result = ssu100_setdevice(dev, data);
        if (result < 0) {
                dev_dbg(&dev->dev, "%s - setdevice failed %i\n", __func__, result);
                goto out;
        }

        result = ssu100_control_msg(dev, QT_GET_SET_PREBUF_TRIG_LVL, 128, 0);
        if (result < 0) {
                dev_dbg(&dev->dev, "%s - set prebuffer level failed %i\n", __func__, result);
                goto out;
        }

        result = ssu100_control_msg(dev, QT_SET_ATF, ATC_DISABLED, 0);
        if (result < 0) {
                dev_dbg(&dev->dev, "%s - set ATFprebuffer level failed %i\n", __func__, result);
                goto out;
        }

        result = ssu100_getdevice(dev, data);
        if (result < 0) {
                dev_dbg(&dev->dev, "%s - get_device failed %i\n", __func__, result);
                goto out;
        }

        data[0] &= ~(RR_BITS | DUPMODE_BITS);
        data[0] |= CLKS_X4;
        data[1] &= ~(LOOPMODE_BITS);
        data[1] |= RS232_MODE;

        result = ssu100_setdevice(dev, data);
        if (result < 0) {
                dev_dbg(&dev->dev, "%s - setdevice failed %i\n", __func__, result);
                goto out;
        }

out:    kfree(data);
        return result;

}


static void ssu100_set_termios(struct tty_struct *tty,
                               struct usb_serial_port *port,
                               const struct ktermios *old_termios)
{
        struct usb_device *dev = port->serial->dev;
        struct ktermios *termios = &tty->termios;
        u16 baud, divisor, remainder;
        unsigned int cflag = termios->c_cflag;
        u16 urb_value = 0; /* will hold the new flags */
        int result;

        if (cflag & PARENB) {
                if (cflag & PARODD)
                        urb_value |= UART_LCR_PARITY;
                else
                        urb_value |= SERIAL_EVEN_PARITY;
        }

        urb_value |= UART_LCR_WLEN(tty_get_char_size(cflag));

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

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


        divisor = MAX_BAUD_RATE / baud;
        remainder = MAX_BAUD_RATE % baud;
        if (((remainder * 2) >= baud) && (baud != 110))
                divisor++;

        urb_value = urb_value << 8;

        result = ssu100_control_msg(dev, QT_GET_SET_UART, divisor, urb_value);
        if (result < 0)
                dev_dbg(&port->dev, "%s - set uart failed\n", __func__);

        if (cflag & CRTSCTS)
                result = ssu100_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
                                            SERIAL_CRTSCTS, 0);
        else
                result = ssu100_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
                                            0, 0);
        if (result < 0)
                dev_dbg(&port->dev, "%s - set HW flow control failed\n", __func__);

        if (I_IXOFF(tty) || I_IXON(tty)) {
                u16 x = ((u16)(START_CHAR(tty) << 8) | (u16)(STOP_CHAR(tty)));

                result = ssu100_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
                                            x, 0);
        } else
                result = ssu100_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
                                            0, 0);

        if (result < 0)
                dev_dbg(&port->dev, "%s - set SW flow control failed\n", __func__);

}


static int ssu100_open(struct tty_struct *tty, struct usb_serial_port *port)
{
        struct usb_device *dev = port->serial->dev;
        struct ssu100_port_private *priv = usb_get_serial_port_data(port);
        u8 *data;
        int result;
        unsigned long flags;

        data = kzalloc(2, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
                                 QT_OPEN_CLOSE_CHANNEL,
                                 QT_TRANSFER_IN, 0x01,
                                 0, data, 2, 300);
        if (result < 2) {
                dev_dbg(&port->dev, "%s - open failed %i\n", __func__, result);
                if (result >= 0)
                        result = -EIO;
                kfree(data);
                return result;
        }

        spin_lock_irqsave(&priv->status_lock, flags);
        priv->shadowLSR = data[0];
        priv->shadowMSR = data[1];
        spin_unlock_irqrestore(&priv->status_lock, flags);

        kfree(data);

/* set to 9600 */
        result = ssu100_control_msg(dev, QT_GET_SET_UART, 0x30, 0x0300);
        if (result < 0)
                dev_dbg(&port->dev, "%s - set uart failed\n", __func__);

        if (tty)
                ssu100_set_termios(tty, port, &tty->termios);

        return usb_serial_generic_open(tty, port);
}

static int ssu100_attach(struct usb_serial *serial)
{
        return ssu100_initdevice(serial->dev);
}

static int ssu100_port_probe(struct usb_serial_port *port)
{
        struct ssu100_port_private *priv;

        priv = kzalloc_obj(*priv);
        if (!priv)
                return -ENOMEM;

        spin_lock_init(&priv->status_lock);

        usb_set_serial_port_data(port, priv);

        return 0;
}

static void ssu100_port_remove(struct usb_serial_port *port)
{
        struct ssu100_port_private *priv;

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

static int ssu100_tiocmget(struct tty_struct *tty)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_device *dev = port->serial->dev;
        u8 *d;
        int r;

        d = kzalloc(2, GFP_KERNEL);
        if (!d)
                return -ENOMEM;

        r = ssu100_getregister(dev, 0, UART_MCR, d);
        if (r < 0)
                goto mget_out;

        r = ssu100_getregister(dev, 0, UART_MSR, d+1);
        if (r < 0)
                goto mget_out;

        r = (d[0] & UART_MCR_DTR ? TIOCM_DTR : 0) |
                (d[0] & UART_MCR_RTS ? TIOCM_RTS : 0) |
                (d[1] & UART_MSR_CTS ? TIOCM_CTS : 0) |
                (d[1] & UART_MSR_DCD ? TIOCM_CAR : 0) |
                (d[1] & UART_MSR_RI ? TIOCM_RI : 0) |
                (d[1] & UART_MSR_DSR ? TIOCM_DSR : 0);

mget_out:
        kfree(d);
        return r;
}

static int ssu100_tiocmset(struct tty_struct *tty,
                           unsigned int set, unsigned int clear)
{
        struct usb_serial_port *port = tty->driver_data;
        struct usb_device *dev = port->serial->dev;

        return update_mctrl(dev, set, clear);
}

static void ssu100_dtr_rts(struct usb_serial_port *port, int on)
{
        struct usb_device *dev = port->serial->dev;

        /* Disable flow control */
        if (!on) {
                if (ssu100_setregister(dev, 0, UART_MCR, 0) < 0)
                        dev_err(&port->dev, "error from flowcontrol urb\n");
        }
        /* drop RTS and DTR */
        if (on)
                set_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
        else
                clear_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
}

static void ssu100_update_msr(struct usb_serial_port *port, u8 msr)
{
        struct ssu100_port_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        spin_lock_irqsave(&priv->status_lock, flags);
        priv->shadowMSR = msr;
        spin_unlock_irqrestore(&priv->status_lock, flags);

        if (msr & UART_MSR_ANY_DELTA) {
                /* update input line counters */
                if (msr & UART_MSR_DCTS)
                        port->icount.cts++;
                if (msr & UART_MSR_DDSR)
                        port->icount.dsr++;
                if (msr & UART_MSR_DDCD)
                        port->icount.dcd++;
                if (msr & UART_MSR_TERI)
                        port->icount.rng++;
                wake_up_interruptible(&port->port.delta_msr_wait);
        }
}

static void ssu100_update_lsr(struct usb_serial_port *port, u8 lsr,
                              char *tty_flag)
{
        struct ssu100_port_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;

        spin_lock_irqsave(&priv->status_lock, flags);
        priv->shadowLSR = lsr;
        spin_unlock_irqrestore(&priv->status_lock, flags);

        *tty_flag = TTY_NORMAL;
        if (lsr & UART_LSR_BRK_ERROR_BITS) {
                /* we always want to update icount, but we only want to
                 * update tty_flag for one case */
                if (lsr & UART_LSR_BI) {
                        port->icount.brk++;
                        *tty_flag = TTY_BREAK;
                        usb_serial_handle_break(port);
                }
                if (lsr & UART_LSR_PE) {
                        port->icount.parity++;
                        if (*tty_flag == TTY_NORMAL)
                                *tty_flag = TTY_PARITY;
                }
                if (lsr & UART_LSR_FE) {
                        port->icount.frame++;
                        if (*tty_flag == TTY_NORMAL)
                                *tty_flag = TTY_FRAME;
                }
                if (lsr & UART_LSR_OE) {
                        port->icount.overrun++;
                        tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
                }
        }

}

static void ssu100_process_read_urb(struct urb *urb)
{
        struct usb_serial_port *port = urb->context;
        char *packet = urb->transfer_buffer;
        char flag = TTY_NORMAL;
        u32 len = urb->actual_length;
        int i;
        char *ch;

        if ((len >= 4) &&
            (packet[0] == 0x1b) && (packet[1] == 0x1b) &&
            ((packet[2] == 0x00) || (packet[2] == 0x01))) {
                if (packet[2] == 0x00)
                        ssu100_update_lsr(port, packet[3], &flag);
                if (packet[2] == 0x01)
                        ssu100_update_msr(port, packet[3]);

                len -= 4;
                ch = packet + 4;
        } else
                ch = packet;

        if (!len)
                return; /* status only */

        if (port->sysrq) {
                for (i = 0; i < len; i++, ch++) {
                        if (!usb_serial_handle_sysrq_char(port, *ch))
                                tty_insert_flip_char(&port->port, *ch, flag);
                }
        } else {
                tty_insert_flip_string_fixed_flag(&port->port, ch, flag, len);
        }

        tty_flip_buffer_push(&port->port);
}

static struct usb_serial_driver ssu100_device = {
        .driver = {
                .name = "ssu100",
        },
        .description         = DRIVER_DESC,
        .id_table            = id_table,
        .num_ports           = 1,
        .open                = ssu100_open,
        .attach              = ssu100_attach,
        .port_probe          = ssu100_port_probe,
        .port_remove         = ssu100_port_remove,
        .dtr_rts             = ssu100_dtr_rts,
        .process_read_urb    = ssu100_process_read_urb,
        .tiocmget            = ssu100_tiocmget,
        .tiocmset            = ssu100_tiocmset,
        .tiocmiwait          = usb_serial_generic_tiocmiwait,
        .get_icount          = usb_serial_generic_get_icount,
        .set_termios         = ssu100_set_termios,
};

static struct usb_serial_driver * const serial_drivers[] = {
        &ssu100_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL v2");