// 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_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/serial_reg.h>
#include <linux/uaccess.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(sizeof(*priv), GFP_KERNEL);
	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");