/*
 * ark3116
 * - implements a driver for the arkmicro ark3116 chipset (vendor=0x6547,
 *   productid=0x0232) (used in a datacable called KQ-U8A)
 *
 * - based on code by krisfx -> thanks !!
 *   (see http://www.linuxquestions.org/questions/showthread.php?p=2184457#post2184457)
 *
 *  - based on logs created by usbsnoopy
 *
 *  Author   : Simon Schulz [ark3116_driver<AT>auctionant.de]
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>


static int debug;

static struct usb_device_id id_table [] = {
	{ USB_DEVICE(0x6547, 0x0232) },
	{ },
};
MODULE_DEVICE_TABLE(usb, id_table);

struct ark3116_private {
	spinlock_t lock;
	u8 termios_initialized;
};

static inline void ARK3116_SND(struct usb_serial *serial, int seq,
			       __u8 request, __u8 requesttype,
			       __u16 value, __u16 index)
{
	int result;
	result = usb_control_msg(serial->dev,
				 usb_sndctrlpipe(serial->dev,0),
				 request, requesttype, value, index,
				 NULL,0x00, 1000);
	dbg("%03d > ok",seq);
}

static inline void ARK3116_RCV(struct usb_serial *serial, int seq,
			       __u8 request, __u8 requesttype,
			       __u16 value, __u16 index, __u8 expected,
			       char *buf)
{
	int result;
	result = usb_control_msg(serial->dev,
			      usb_rcvctrlpipe(serial->dev,0),
			      request, requesttype, value, index,
			      buf, 0x0000001, 1000);
	if (result)
		dbg("%03d < %d bytes [0x%02X]",seq, result, buf[0]);
	else
		dbg("%03d < 0 bytes", seq);
}


static inline void ARK3116_RCV_QUIET(struct usb_serial *serial,
				     __u8 request, __u8 requesttype,
				     __u16 value, __u16 index, char *buf)
{
	usb_control_msg(serial->dev,
			usb_rcvctrlpipe(serial->dev,0),
			request, requesttype, value, index,
			buf, 0x0000001, 1000);
}


static int ark3116_attach(struct usb_serial *serial)
{
	char *buf;
	struct ark3116_private *priv;
	int i;

	for (i = 0; i < serial->num_ports; ++i) {
		priv = kmalloc (sizeof (struct ark3116_private), GFP_KERNEL);
		if (!priv)
			goto cleanup;
		memset (priv, 0x00, sizeof (struct ark3116_private));
		spin_lock_init(&priv->lock);

		usb_set_serial_port_data(serial->port[i], priv);
	}

	buf = kmalloc(1, GFP_KERNEL);
	if (!buf) {
		dbg("error kmalloc -> out of mem ?");
		goto cleanup;
	}

	/* 3 */
	ARK3116_SND(serial, 3,0xFE,0x40,0x0008,0x0002);
	ARK3116_SND(serial, 4,0xFE,0x40,0x0008,0x0001);
	ARK3116_SND(serial, 5,0xFE,0x40,0x0000,0x0008);
	ARK3116_SND(serial, 6,0xFE,0x40,0x0000,0x000B);

	/* <-- seq7 */
	ARK3116_RCV(serial, 7,0xFE,0xC0,0x0000,0x0003, 0x00, buf);
	ARK3116_SND(serial, 8,0xFE,0x40,0x0080,0x0003);
	ARK3116_SND(serial, 9,0xFE,0x40,0x001A,0x0000);
	ARK3116_SND(serial,10,0xFE,0x40,0x0000,0x0001);
	ARK3116_SND(serial,11,0xFE,0x40,0x0000,0x0003);

	/* <-- seq12 */
	ARK3116_RCV(serial,12,0xFE,0xC0,0x0000,0x0004, 0x00, buf);
	ARK3116_SND(serial,13,0xFE,0x40,0x0000,0x0004);

	/* 14 */
	ARK3116_RCV(serial,14,0xFE,0xC0,0x0000,0x0004, 0x00, buf);
	ARK3116_SND(serial,15,0xFE,0x40,0x0000,0x0004);

	/* 16 */
	ARK3116_RCV(serial,16,0xFE,0xC0,0x0000,0x0004, 0x00, buf);
	/* --> seq17 */
	ARK3116_SND(serial,17,0xFE,0x40,0x0001,0x0004);

	/* <-- seq18 */
	ARK3116_RCV(serial,18,0xFE,0xC0,0x0000,0x0004, 0x01, buf);

	/* --> seq19 */
	ARK3116_SND(serial,19,0xFE,0x40,0x0003,0x0004);


	/* <-- seq20 */
	/* seems like serial port status info (RTS, CTS,...) */
	/* returns modem control line status ?! */
	ARK3116_RCV(serial,20,0xFE,0xC0,0x0000,0x0006, 0xFF, buf);

	/* set 9600 baud & do some init ?! */
	ARK3116_SND(serial,147,0xFE,0x40,0x0083,0x0003);
	ARK3116_SND(serial,148,0xFE,0x40,0x0038,0x0000);
	ARK3116_SND(serial,149,0xFE,0x40,0x0001,0x0001);
	ARK3116_SND(serial,150,0xFE,0x40,0x0003,0x0003);
	ARK3116_RCV(serial,151,0xFE,0xC0,0x0000,0x0004,0x03, buf);
	ARK3116_SND(serial,152,0xFE,0x40,0x0000,0x0003);
	ARK3116_RCV(serial,153,0xFE,0xC0,0x0000,0x0003,0x00, buf);
	ARK3116_SND(serial,154,0xFE,0x40,0x0003,0x0003);

	kfree(buf);
	return(0);

cleanup:
	for (--i; i>=0; --i)
		usb_set_serial_port_data(serial->port[i], NULL);
	return -ENOMEM;
}

static void ark3116_set_termios(struct usb_serial_port *port,
				struct termios *old_termios)
{
	struct usb_serial *serial = port->serial;
	struct ark3116_private *priv = usb_get_serial_port_data(port);
	unsigned int cflag = port->tty->termios->c_cflag;
	unsigned long flags;
	int baud;
	int ark3116_baud;
	char *buf;
	char config;

	config = 0;

	dbg("%s - port %d", __FUNCTION__, port->number);

	if ((!port->tty) || (!port->tty->termios)) {
		dbg("%s - no tty structures", __FUNCTION__);
		return;
	}

	spin_lock_irqsave(&priv->lock, flags);
	if (!priv->termios_initialized) {
		*(port->tty->termios) = tty_std_termios;
		port->tty->termios->c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
		priv->termios_initialized = 1;
	}
	spin_unlock_irqrestore(&priv->lock, flags);

	cflag = port->tty->termios->c_cflag;

	/* check that they really want us to change something: */
	if (old_termios) {
		if ((cflag == old_termios->c_cflag) &&
		    (RELEVANT_IFLAG(port->tty->termios->c_iflag) ==
		     RELEVANT_IFLAG(old_termios->c_iflag))) {
			dbg("%s - nothing to change...", __FUNCTION__);
			return;
		}
	}

	buf = kmalloc(1, GFP_KERNEL);
	if (!buf) {
		dbg("error kmalloc");
		return;
	}

	/* set data bit count (8/7/6/5) */
	if (cflag & CSIZE){
		switch (cflag & CSIZE){
		case CS5:
			config |= 0x00;
			dbg("setting CS5");
			break;
		case CS6:
			config |= 0x01;
			dbg("setting CS6");
			break;
		case CS7:
			config |= 0x02;
			dbg("setting CS7");
			break;
		default:
			err ("CSIZE was set but not CS5-CS8, using CS8!");
		case CS8:
			config |= 0x03;
			dbg("setting CS8");
			break;
		}
	}

	/* set parity (NONE,EVEN,ODD) */
	if (cflag & PARENB){
		if (cflag & PARODD) {
			config |= 0x08;
			dbg("setting parity to ODD");
		} else {
			config |= 0x18;
			dbg("setting parity to EVEN");
		}
	} else {
		dbg("setting parity to NONE");
	}

	/* SET STOPBIT (1/2) */
	if (cflag & CSTOPB) {
		config |= 0x04;
		dbg ("setting 2 stop bits");
	} else {
		dbg ("setting 1 stop bit");
	}


	/* set baudrate: */
	baud = 0;
	switch (cflag & CBAUD){
		case B0:
			err("can't set 0baud, using 9600 instead");
			break;
		case B75:	baud = 75;	break;
		case B150:	baud = 150;	break;
		case B300:	baud = 300;	break;
		case B600:	baud = 600;	break;
		case B1200:	baud = 1200;	break;
		case B1800:	baud = 1800;	break;
		case B2400:	baud = 2400;	break;
		case B4800:	baud = 4800;	break;
		case B9600:	baud = 9600;	break;
		case B19200:	baud = 19200;	break;
		case B38400:	baud = 38400;	break;
		case B57600:	baud = 57600;	break;
		case B115200:	baud = 115200;	break;
		case B230400:	baud = 230400;	break;
		case B460800:	baud = 460800;	break;
		default:
			dbg("does not support the baudrate requested (fix it)");
			break;
	}

	/* set 9600 as default (if given baudrate is invalid for example) */
	if (baud == 0)
		baud = 9600;

	/*
	 * found by try'n'error, be careful, maybe there are other options
	 * for multiplicator etc!
	 */
	if (baud == 460800)
		/* strange, for 460800 the formula is wrong
		 * (dont use round(), then 9600baud is wrong) */
		ark3116_baud = 7;
	else
		ark3116_baud = 3000000 / baud;

	/* ? */
	ARK3116_RCV(serial,0,0xFE,0xC0,0x0000,0x0003, 0x03, buf);
	/* offset = buf[0]; */
	/* offset = 0x03; */
	/* dbg("using 0x%04X as target for 0x0003:",0x0080+offset); */


	/* set baudrate */
	dbg("setting baudrate to %d (->reg=%d)",baud,ark3116_baud);
	ARK3116_SND(serial,147,0xFE,0x40,0x0083,0x0003);
	ARK3116_SND(serial,148,0xFE,0x40,(ark3116_baud & 0x00FF)   ,0x0000);
	ARK3116_SND(serial,149,0xFE,0x40,(ark3116_baud & 0xFF00)>>8,0x0001);
	ARK3116_SND(serial,150,0xFE,0x40,0x0003,0x0003);

	/* ? */
	ARK3116_RCV(serial,151,0xFE,0xC0,0x0000,0x0004,0x03, buf);
	ARK3116_SND(serial,152,0xFE,0x40,0x0000,0x0003);

	/* set data bit count, stop bit count & parity: */
	dbg("updating bit count, stop bit or parity (cfg=0x%02X)", config);
	ARK3116_RCV(serial,153,0xFE,0xC0,0x0000,0x0003,0x00, buf);
	ARK3116_SND(serial,154,0xFE,0x40,config,0x0003);

	if (cflag & CRTSCTS)
		dbg("CRTSCTS not supported by chipset ?!");

	/* TEST ARK3116_SND(154,0xFE,0x40,0xFFFF, 0x0006); */

	kfree(buf);
	return;
}

static int ark3116_open(struct usb_serial_port *port, struct file *filp)
{
	struct termios tmp_termios;
	struct usb_serial *serial = port->serial;
	char *buf;
	int result = 0;

	dbg("%s -  port %d", __FUNCTION__, port->number);

	buf = kmalloc(1, GFP_KERNEL);
	if (!buf) {
		dbg("error kmalloc -> out of mem ?");
		return -ENOMEM;
	}

	result = usb_serial_generic_open(port, filp);
	if (result)
		return result;

	/* open */
	ARK3116_RCV(serial,111,0xFE,0xC0,0x0000,0x0003, 0x02, buf);

	ARK3116_SND(serial,112,0xFE,0x40,0x0082,0x0003);
	ARK3116_SND(serial,113,0xFE,0x40,0x001A,0x0000);
	ARK3116_SND(serial,114,0xFE,0x40,0x0000,0x0001);
	ARK3116_SND(serial,115,0xFE,0x40,0x0002,0x0003);

	ARK3116_RCV(serial,116,0xFE,0xC0,0x0000,0x0004, 0x03, buf);
	ARK3116_SND(serial,117,0xFE,0x40,0x0002,0x0004);

	ARK3116_RCV(serial,118,0xFE,0xC0,0x0000,0x0004, 0x02, buf);
	ARK3116_SND(serial,119,0xFE,0x40,0x0000,0x0004);

	ARK3116_RCV(serial,120,0xFE,0xC0,0x0000,0x0004, 0x00, buf);

	ARK3116_SND(serial,121,0xFE,0x40,0x0001,0x0004);

	ARK3116_RCV(serial,122,0xFE,0xC0,0x0000,0x0004, 0x01, buf);

	ARK3116_SND(serial,123,0xFE,0x40,0x0003,0x0004);

	/* returns different values (control lines ?!) */
	ARK3116_RCV(serial,124,0xFE,0xC0,0x0000,0x0006, 0xFF, buf);

	/* initialise termios: */
	if (port->tty)
		ark3116_set_termios(port, &tmp_termios);

	kfree(buf);

	return result;

}

static int ark3116_ioctl(struct usb_serial_port *port, struct file *file,
			 unsigned int cmd, unsigned long arg)
{
	dbg("ioctl not supported yet...");
	return -ENOIOCTLCMD;
}

static int ark3116_tiocmget(struct usb_serial_port *port, struct file *file)
{
	struct usb_serial *serial = port->serial;
	char *buf;
	char temp;

	/* seems like serial port status info (RTS, CTS,...) is stored
	 * in reg(?) 0x0006
	 * pcb connection point 11 = GND -> sets bit4 of response
	 * pcb connection point  7 = GND -> sets bit6 of response
	 */

	buf = kmalloc(1, GFP_KERNEL);
	if (!buf) {
		dbg("error kmalloc");
		return -ENOMEM;
	}

	/* read register: */
	ARK3116_RCV_QUIET(serial,0xFE,0xC0,0x0000,0x0006,buf);
	temp = buf[0];
	kfree(buf);

	/* i do not really know if bit4=CTS and bit6=DSR... was just a
	 * quick guess !!
	 */
	return  (temp & (1<<4) ? TIOCM_CTS : 0) |
	        (temp & (1<<6) ? TIOCM_DSR : 0);
}

static struct usb_driver ark3116_driver = {
	.name =		"ark3116",
	.probe =	usb_serial_probe,
	.disconnect =	usb_serial_disconnect,
	.id_table =	id_table,
};

static struct usb_serial_driver ark3116_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"ark3116",
	},
	.id_table =		id_table,
	.num_interrupt_in =	1,
	.num_bulk_in =		1,
	.num_bulk_out =		1,
	.num_ports =		1,
	.attach =		ark3116_attach,
	.set_termios =		ark3116_set_termios,
	.ioctl =		ark3116_ioctl,
	.tiocmget =		ark3116_tiocmget,
	.open =			ark3116_open,
};

static int __init ark3116_init(void)
{
	int retval;

	retval = usb_serial_register(&ark3116_device);
	if (retval)
		return retval;
	retval = usb_register(&ark3116_driver);
	if (retval)
		usb_serial_deregister(&ark3116_device);
	return retval;
}

static void __exit ark3116_exit(void)
{
	usb_deregister(&ark3116_driver);
	usb_serial_deregister(&ark3116_device);
}

module_init(ark3116_init);
module_exit(ark3116_exit);
MODULE_LICENSE("GPL");

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");