/*
   * linux/drivers/char/pcmcia/synclink_cs.c
   *

   * $Id: synclink_cs.c,v 4.34 2005/09/08 13:20:54 paulkf Exp $

   *
   * Device driver for Microgate SyncLink PC Card
   * multiprotocol serial adapter.
   *
   * written by Paul Fulghum for Microgate Corporation
   * paulkf@microgate.com
   *
   * Microgate and SyncLink are trademarks of Microgate Corporation
   *
   * This code is released under the GNU General Public License (GPL)
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #define VERSION(ver,rel,seq) (((ver)<<16) | ((rel)<<8) | (seq))
  #if defined(__i386__)
  #  define BREAKPOINT() asm("   int $3");
  #else
  #  define BREAKPOINT() { }
  #endif
  
  #define MAX_DEVICE_COUNT 4

  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/signal.h>
  #include <linux/sched.h>
  #include <linux/timer.h>
  #include <linux/time.h>
  #include <linux/interrupt.h>

  #include <linux/tty.h>
  #include <linux/tty_flip.h>
  #include <linux/serial.h>
  #include <linux/major.h>
  #include <linux/string.h>
  #include <linux/fcntl.h>
  #include <linux/ptrace.h>
  #include <linux/ioport.h>
  #include <linux/mm.h>

  #include <linux/seq_file.h>

  #include <linux/slab.h>
  #include <linux/netdevice.h>
  #include <linux/vmalloc.h>
  #include <linux/init.h>

  #include <linux/delay.h>
  #include <linux/ioctl.h>

  #include <linux/synclink.h>

  #include <asm/io.h>
  #include <asm/irq.h>
  #include <asm/dma.h>
  #include <linux/bitops.h>
  #include <asm/types.h>
  #include <linux/termios.h>
  #include <linux/workqueue.h>
  #include <linux/hdlc.h>

  #include <pcmcia/cistpl.h>
  #include <pcmcia/cisreg.h>
  #include <pcmcia/ds.h>

  #if defined(CONFIG_HDLC) || (defined(CONFIG_HDLC_MODULE) && defined(CONFIG_SYNCLINK_CS_MODULE))
  #define SYNCLINK_GENERIC_HDLC 1
  #else
  #define SYNCLINK_GENERIC_HDLC 0

  #endif
  
  #define GET_USER(error,value,addr) error = get_user(value,addr)
  #define COPY_FROM_USER(error,dest,src,size) error = copy_from_user(dest,src,size) ? -EFAULT : 0
  #define PUT_USER(error,value,addr) error = put_user(value,addr)
  #define COPY_TO_USER(error,dest,src,size) error = copy_to_user(dest,src,size) ? -EFAULT : 0
  
  #include <asm/uaccess.h>

  static MGSL_PARAMS default_params = {
  	MGSL_MODE_HDLC,			/* unsigned long mode */
  	0,				/* unsigned char loopback; */
  	HDLC_FLAG_UNDERRUN_ABORT15,	/* unsigned short flags; */
  	HDLC_ENCODING_NRZI_SPACE,	/* unsigned char encoding; */
  	0,				/* unsigned long clock_speed; */
  	0xff,				/* unsigned char addr_filter; */
  	HDLC_CRC_16_CCITT,		/* unsigned short crc_type; */
  	HDLC_PREAMBLE_LENGTH_8BITS,	/* unsigned char preamble_length; */
  	HDLC_PREAMBLE_PATTERN_NONE,	/* unsigned char preamble; */
  	9600,				/* unsigned long data_rate; */
  	8,				/* unsigned char data_bits; */
  	1,				/* unsigned char stop_bits; */
  	ASYNC_PARITY_NONE		/* unsigned char parity; */
  };

  typedef struct {

  	int count;
  	unsigned char status;
  	char data[1];
  } RXBUF;
  
  /* The queue of BH actions to be performed */
  
  #define BH_RECEIVE  1
  #define BH_TRANSMIT 2
  #define BH_STATUS   4
  
  #define IO_PIN_SHUTDOWN_LIMIT 100
  
  #define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
  
  struct _input_signal_events {

  	int	ri_up;

  	int	ri_down;
  	int	dsr_up;
  	int	dsr_down;
  	int	dcd_up;
  	int	dcd_down;
  	int	cts_up;
  	int	cts_down;
  };
  
  
  /*
   * Device instance data structure
   */

  typedef struct _mgslpc_info {

  	struct tty_port		port;

  	void *if_ptr;	/* General purpose pointer (used by SPPP) */
  	int			magic;

  	int			line;

  	struct mgsl_icount	icount;

  	int			timeout;
  	int			x_char;		/* xon/xoff character */

  	unsigned char		read_status_mask;

  	unsigned char		ignore_status_mask;

  
  	unsigned char *tx_buf;
  	int            tx_put;
  	int            tx_get;
  	int            tx_count;
  
  	/* circular list of fixed length rx buffers */
  
  	unsigned char  *rx_buf;        /* memory allocated for all rx buffers */
  	int            rx_buf_total_size; /* size of memory allocated for rx buffers */
  	int            rx_put;         /* index of next empty rx buffer */
  	int            rx_get;         /* index of next full rx buffer */
  	int            rx_buf_size;    /* size in bytes of single rx buffer */
  	int            rx_buf_count;   /* total number of rx buffers */
  	int            rx_frame_count; /* number of full rx buffers */

  	wait_queue_head_t	status_event_wait_q;
  	wait_queue_head_t	event_wait_q;
  	struct timer_list	tx_timer;	/* HDLC transmit timeout timer */
  	struct _mgslpc_info	*next_device;	/* device list link */
  
  	unsigned short imra_value;
  	unsigned short imrb_value;
  	unsigned char  pim_value;
  
  	spinlock_t lock;
  	struct work_struct task;		/* task structure for scheduling bh */
  
  	u32 max_frame_size;
  
  	u32 pending_bh;

  	bool bh_running;
  	bool bh_requested;

  	int dcd_chkcount; /* check counts to prevent */
  	int cts_chkcount; /* too many IRQs if a signal */
  	int dsr_chkcount; /* is floating */
  	int ri_chkcount;

  	bool rx_enabled;
  	bool rx_overflow;

  	bool tx_enabled;
  	bool tx_active;
  	bool tx_aborting;

  	u32 idle_mode;
  
  	int if_mode; /* serial interface selection (RS-232, v.35 etc) */
  
  	char device_name[25];		/* device instance name */
  
  	unsigned int io_base;	/* base I/O address of adapter */
  	unsigned int irq_level;

  	MGSL_PARAMS params;		/* communications parameters */
  
  	unsigned char serial_signals;	/* current serial signal states */

  	bool irq_occurred;		/* for diagnostics use */

  	char testing_irq;
  	unsigned int init_error;	/* startup error (DIAGS)	*/

  	char *flag_buf;

  	bool drop_rts_on_tx_done;

  
  	struct	_input_signal_events	input_signal_events;
  
  	/* PCMCIA support */

  	struct pcmcia_device	*p_dev;

  	int		      stop;
  
  	/* SPPP/Cisco HDLC device parts */
  	int netcount;

  	spinlock_t netlock;

  #if SYNCLINK_GENERIC_HDLC

  	struct net_device *netdev;
  #endif
  
  } MGSLPC_INFO;
  
  #define MGSLPC_MAGIC 0x5402
  
  /*
   * The size of the serial xmit buffer is 1 page, or 4096 bytes
   */
  #define TXBUFSIZE 4096

  #define CHA     0x00   /* channel A offset */
  #define CHB     0x40   /* channel B offset */
  
  /*
   *  FIXME: PPC has PVR defined in asm/reg.h.  For now we just undef it.
   */
  #undef PVR
  
  #define RXFIFO  0
  #define TXFIFO  0
  #define STAR    0x20
  #define CMDR    0x20
  #define RSTA    0x21
  #define PRE     0x21
  #define MODE    0x22
  #define TIMR    0x23
  #define XAD1    0x24
  #define XAD2    0x25
  #define RAH1    0x26
  #define RAH2    0x27
  #define DAFO    0x27
  #define RAL1    0x28
  #define RFC     0x28
  #define RHCR    0x29
  #define RAL2    0x29
  #define RBCL    0x2a
  #define XBCL    0x2a
  #define RBCH    0x2b
  #define XBCH    0x2b
  #define CCR0    0x2c
  #define CCR1    0x2d
  #define CCR2    0x2e
  #define CCR3    0x2f
  #define VSTR    0x34
  #define BGR     0x34
  #define RLCR    0x35
  #define AML     0x36
  #define AMH     0x37
  #define GIS     0x38
  #define IVA     0x38
  #define IPC     0x39
  #define ISR     0x3a
  #define IMR     0x3a
  #define PVR     0x3c
  #define PIS     0x3d
  #define PIM     0x3d
  #define PCR     0x3e
  #define CCR4    0x3f

  // IMR/ISR

  #define IRQ_BREAK_ON    BIT15   // rx break detected
  #define IRQ_DATAOVERRUN BIT14	// receive data overflow
  #define IRQ_ALLSENT     BIT13	// all sent
  #define IRQ_UNDERRUN    BIT12	// transmit data underrun
  #define IRQ_TIMER       BIT11	// timer interrupt
  #define IRQ_CTS         BIT10	// CTS status change
  #define IRQ_TXREPEAT    BIT9	// tx message repeat
  #define IRQ_TXFIFO      BIT8	// transmit pool ready
  #define IRQ_RXEOM       BIT7	// receive message end
  #define IRQ_EXITHUNT    BIT6	// receive frame start
  #define IRQ_RXTIME      BIT6    // rx char timeout
  #define IRQ_DCD         BIT2	// carrier detect status change
  #define IRQ_OVERRUN     BIT1	// receive frame overflow
  #define IRQ_RXFIFO      BIT0	// receive pool full

  // STAR

  #define XFW   BIT6		// transmit FIFO write enable
  #define CEC   BIT2		// command executing
  #define CTS   BIT1		// CTS state

  #define PVR_DTR      BIT0
  #define PVR_DSR      BIT1
  #define PVR_RI       BIT2
  #define PVR_AUTOCTS  BIT3
  #define PVR_RS232    0x20   /* 0010b */
  #define PVR_V35      0xe0   /* 1110b */
  #define PVR_RS422    0x40   /* 0100b */

  
  /* Register access functions */

  #define write_reg(info, reg, val) outb((val),(info)->io_base + (reg))
  #define read_reg(info, reg) inb((info)->io_base + (reg))

  #define read_reg16(info, reg) inw((info)->io_base + (reg))

  #define write_reg16(info, reg, val) outw((val), (info)->io_base + (reg))

  #define set_reg_bits(info, reg, mask) \

  	write_reg(info, (reg), \

  		 (unsigned char) (read_reg(info, (reg)) | (mask)))

  #define clear_reg_bits(info, reg, mask) \

  	write_reg(info, (reg), \

  		 (unsigned char) (read_reg(info, (reg)) & ~(mask)))

  /*
   * interrupt enable/disable routines

   */
  static void irq_disable(MGSLPC_INFO *info, unsigned char channel, unsigned short mask)

  {
  	if (channel == CHA) {
  		info->imra_value |= mask;
  		write_reg16(info, CHA + IMR, info->imra_value);
  	} else {
  		info->imrb_value |= mask;
  		write_reg16(info, CHB + IMR, info->imrb_value);
  	}
  }

  static void irq_enable(MGSLPC_INFO *info, unsigned char channel, unsigned short mask)

  {
  	if (channel == CHA) {
  		info->imra_value &= ~mask;
  		write_reg16(info, CHA + IMR, info->imra_value);
  	} else {
  		info->imrb_value &= ~mask;
  		write_reg16(info, CHB + IMR, info->imrb_value);
  	}
  }
  
  #define port_irq_disable(info, mask) \

  	{ info->pim_value |= (mask); write_reg(info, PIM, info->pim_value); }

  
  #define port_irq_enable(info, mask) \

  	{ info->pim_value &= ~(mask); write_reg(info, PIM, info->pim_value); }

  
  static void rx_start(MGSLPC_INFO *info);
  static void rx_stop(MGSLPC_INFO *info);

  static void tx_start(MGSLPC_INFO *info, struct tty_struct *tty);

  static void tx_stop(MGSLPC_INFO *info);
  static void tx_set_idle(MGSLPC_INFO *info);
  
  static void get_signals(MGSLPC_INFO *info);
  static void set_signals(MGSLPC_INFO *info);
  
  static void reset_device(MGSLPC_INFO *info);
  
  static void hdlc_mode(MGSLPC_INFO *info);
  static void async_mode(MGSLPC_INFO *info);
  
  static void tx_timeout(unsigned long context);

  static int carrier_raised(struct tty_port *port);

  static void dtr_rts(struct tty_port *port, int onoff);

  #if SYNCLINK_GENERIC_HDLC

  #define dev_to_port(D) (dev_to_hdlc(D)->priv)
  static void hdlcdev_tx_done(MGSLPC_INFO *info);
  static void hdlcdev_rx(MGSLPC_INFO *info, char *buf, int size);
  static int  hdlcdev_init(MGSLPC_INFO *info);
  static void hdlcdev_exit(MGSLPC_INFO *info);
  #endif
  
  static void trace_block(MGSLPC_INFO *info,const char* data, int count, int xmit);

  static bool register_test(MGSLPC_INFO *info);
  static bool irq_test(MGSLPC_INFO *info);

  static int adapter_test(MGSLPC_INFO *info);
  
  static int claim_resources(MGSLPC_INFO *info);
  static void release_resources(MGSLPC_INFO *info);

  static int mgslpc_add_device(MGSLPC_INFO *info);

  static void mgslpc_remove_device(MGSLPC_INFO *info);

  static bool rx_get_frame(MGSLPC_INFO *info, struct tty_struct *tty);

  static void rx_reset_buffers(MGSLPC_INFO *info);
  static int  rx_alloc_buffers(MGSLPC_INFO *info);
  static void rx_free_buffers(MGSLPC_INFO *info);

  static irqreturn_t mgslpc_isr(int irq, void *dev_id);

  
  /*
   * Bottom half interrupt handlers
   */

  static void bh_handler(struct work_struct *work);

  static void bh_transmit(MGSLPC_INFO *info, struct tty_struct *tty);

  static void bh_status(MGSLPC_INFO *info);
  
  /*
   * ioctl handlers
   */

  static int tiocmget(struct tty_struct *tty);

  static int tiocmset(struct tty_struct *tty,
  					unsigned int set, unsigned int clear);

  static int get_stats(MGSLPC_INFO *info, struct mgsl_icount __user *user_icount);
  static int get_params(MGSLPC_INFO *info, MGSL_PARAMS __user *user_params);

  static int set_params(MGSLPC_INFO *info, MGSL_PARAMS __user *new_params, struct tty_struct *tty);

  static int get_txidle(MGSLPC_INFO *info, int __user *idle_mode);
  static int set_txidle(MGSLPC_INFO *info, int idle_mode);

  static int set_txenable(MGSLPC_INFO *info, int enable, struct tty_struct *tty);

  static int tx_abort(MGSLPC_INFO *info);
  static int set_rxenable(MGSLPC_INFO *info, int enable);
  static int wait_events(MGSLPC_INFO *info, int __user *mask);
  
  static MGSLPC_INFO *mgslpc_device_list = NULL;
  static int mgslpc_device_count = 0;
  
  /*
   * Set this param to non-zero to load eax with the
   * .text section address and breakpoint on module load.
   * This is useful for use with gdb and add-symbol-file command.
   */

  static bool break_on_load;

  
  /*
   * Driver major number, defaults to zero to get auto
   * assigned major number. May be forced as module parameter.
   */
  static int ttymajor=0;
  
  static int debug_level = 0;
  static int maxframe[MAX_DEVICE_COUNT] = {0,};

  
  module_param(break_on_load, bool, 0);
  module_param(ttymajor, int, 0);
  module_param(debug_level, int, 0);
  module_param_array(maxframe, int, NULL, 0);

  
  MODULE_LICENSE("GPL");
  
  static char *driver_name = "SyncLink PC Card driver";

  static char *driver_version = "$Revision: 4.34 $";

  
  static struct tty_driver *serial_driver;
  
  /* number of characters left in xmit buffer before we ask for more */
  #define WAKEUP_CHARS 256

  static void mgslpc_change_params(MGSLPC_INFO *info, struct tty_struct *tty);

  static void mgslpc_wait_until_sent(struct tty_struct *tty, int timeout);
  
  /* PCMCIA prototypes */

  static int mgslpc_config(struct pcmcia_device *link);

  static void mgslpc_release(u_long arg);

  static void mgslpc_detach(struct pcmcia_device *p_dev);

  /*
   * 1st function defined in .text section. Calling this function in
   * init_module() followed by a breakpoint allows a remote debugger
   * (gdb) to get the .text address for the add-symbol-file command.
   * This allows remote debugging of dynamically loadable modules.
   */
  static void* mgslpc_get_text_ptr(void)
  {
  	return mgslpc_get_text_ptr;
  }
  
  /**
   * line discipline callback wrappers
   *
   * The wrappers maintain line discipline references
   * while calling into the line discipline.
   *

   * ldisc_receive_buf  - pass receive data to line discipline
   */

  static void ldisc_receive_buf(struct tty_struct *tty,
  			      const __u8 *data, char *flags, int count)
  {
  	struct tty_ldisc *ld;
  	if (!tty)
  		return;
  	ld = tty_ldisc_ref(tty);
  	if (ld) {

  		if (ld->ops->receive_buf)
  			ld->ops->receive_buf(tty, data, flags, count);

  		tty_ldisc_deref(ld);
  	}
  }

  static const struct tty_port_operations mgslpc_port_ops = {
  	.carrier_raised = carrier_raised,

  	.dtr_rts = dtr_rts

  };

  static int mgslpc_probe(struct pcmcia_device *link)

  {

  	MGSLPC_INFO *info;
  	int ret;
  
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("mgslpc_attach
  ");
  
  	info = kzalloc(sizeof(MGSLPC_INFO), GFP_KERNEL);
  	if (!info) {
  		printk("Error can't allocate device instance data
  ");
  		return -ENOMEM;
  	}
  
  	info->magic = MGSLPC_MAGIC;
  	tty_port_init(&info->port);
  	info->port.ops = &mgslpc_port_ops;
  	INIT_WORK(&info->task, bh_handler);
  	info->max_frame_size = 4096;
  	info->port.close_delay = 5*HZ/10;
  	info->port.closing_wait = 30*HZ;
  	init_waitqueue_head(&info->status_event_wait_q);
  	init_waitqueue_head(&info->event_wait_q);
  	spin_lock_init(&info->lock);
  	spin_lock_init(&info->netlock);
  	memcpy(&info->params,&default_params,sizeof(MGSL_PARAMS));
  	info->idle_mode = HDLC_TXIDLE_FLAGS;
  	info->imra_value = 0xffff;
  	info->imrb_value = 0xffff;
  	info->pim_value = 0xff;
  
  	info->p_dev = link;
  	link->priv = info;
  
  	/* Initialize the struct pcmcia_device structure */
  
  	ret = mgslpc_config(link);
  	if (ret != 0)
  		goto failed;
  
  	ret = mgslpc_add_device(info);
  	if (ret != 0)
  		goto failed_release;
  
  	return 0;

  
  failed_release:

  	mgslpc_release((u_long)link);

  failed:

  	tty_port_destroy(&info->port);
  	kfree(info);
  	return ret;

  }
  
  /* Card has been inserted.
   */

  static int mgslpc_ioprobe(struct pcmcia_device *p_dev, void *priv_data)

  {

  	return pcmcia_request_io(p_dev);

  }

  static int mgslpc_config(struct pcmcia_device *link)

  {

  	MGSLPC_INFO *info = link->priv;
  	int ret;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("mgslpc_config(0x%p)
  ", link);

  	link->config_flags |= CONF_ENABLE_IRQ | CONF_AUTO_SET_IO;

  	ret = pcmcia_loop_config(link, mgslpc_ioprobe, NULL);
  	if (ret != 0)
  		goto failed;

  	link->config_index = 8;
  	link->config_regs = PRESENT_OPTION;

  	ret = pcmcia_request_irq(link, mgslpc_isr);
  	if (ret)
  		goto failed;
  	ret = pcmcia_enable_device(link);
  	if (ret)
  		goto failed;

  	info->io_base = link->resource[0]->start;
  	info->irq_level = link->irq;
  	return 0;

  failed:

  	mgslpc_release((u_long)link);
  	return -ENODEV;

  }
  
  /* Card has been removed.
   * Unregister device and release PCMCIA configuration.
   * If device is open, postpone until it is closed.
   */
  static void mgslpc_release(u_long arg)
  {

  	struct pcmcia_device *link = (struct pcmcia_device *)arg;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("mgslpc_release(0x%p)
  ", link);

  	pcmcia_disable_device(link);

  }

  static void mgslpc_detach(struct pcmcia_device *link)

  {

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("mgslpc_detach(0x%p)
  ", link);

  	((MGSLPC_INFO *)link->priv)->stop = 1;
  	mgslpc_release((u_long)link);

  	mgslpc_remove_device((MGSLPC_INFO *)link->priv);

  }

  static int mgslpc_suspend(struct pcmcia_device *link)

  {

  	MGSLPC_INFO *info = link->priv;

  	info->stop = 1;

  
  	return 0;
  }

  static int mgslpc_resume(struct pcmcia_device *link)

  {

  	MGSLPC_INFO *info = link->priv;

  	info->stop = 0;
  
  	return 0;
  }

  static inline bool mgslpc_paranoia_check(MGSLPC_INFO *info,

  					char *name, const char *routine)
  {
  #ifdef MGSLPC_PARANOIA_CHECK
  	static const char *badmagic =
  		"Warning: bad magic number for mgsl struct (%s) in %s
  ";
  	static const char *badinfo =
  		"Warning: null mgslpc_info for (%s) in %s
  ";
  
  	if (!info) {
  		printk(badinfo, name, routine);

  		return true;

  	}
  	if (info->magic != MGSLPC_MAGIC) {
  		printk(badmagic, name, routine);

  		return true;

  	}
  #else
  	if (!info)

  		return true;

  #endif

  	return false;

  }
  
  
  #define CMD_RXFIFO      BIT7	// release current rx FIFO
  #define CMD_RXRESET     BIT6	// receiver reset
  #define CMD_RXFIFO_READ BIT5
  #define CMD_START_TIMER BIT4
  #define CMD_TXFIFO      BIT3	// release current tx FIFO
  #define CMD_TXEOM       BIT1	// transmit end message
  #define CMD_TXRESET     BIT0	// transmit reset

  static bool wait_command_complete(MGSLPC_INFO *info, unsigned char channel)

  {
  	int i = 0;

  	/* wait for command completion */

  	while (read_reg(info, (unsigned char)(channel+STAR)) & BIT2) {
  		udelay(1);
  		if (i++ == 1000)

  			return false;

  	}

  	return true;

  }

  static void issue_command(MGSLPC_INFO *info, unsigned char channel, unsigned char cmd)

  {
  	wait_command_complete(info, channel);
  	write_reg(info, (unsigned char) (channel + CMDR), cmd);
  }
  
  static void tx_pause(struct tty_struct *tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (mgslpc_paranoia_check(info, tty->name, "tx_pause"))
  		return;
  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("tx_pause(%s)
  ", info->device_name);

  	spin_lock_irqsave(&info->lock, flags);

  	if (info->tx_enabled)

  		tx_stop(info);
  	spin_unlock_irqrestore(&info->lock, flags);

  }
  
  static void tx_release(struct tty_struct *tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (mgslpc_paranoia_check(info, tty->name, "tx_release"))
  		return;
  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("tx_release(%s)
  ", info->device_name);

  	spin_lock_irqsave(&info->lock, flags);

  	if (!info->tx_enabled)

  		tx_start(info, tty);
  	spin_unlock_irqrestore(&info->lock, flags);

  }
  
  /* Return next bottom half action to perform.
   * or 0 if nothing to do.
   */
  static int bh_action(MGSLPC_INFO *info)
  {
  	unsigned long flags;
  	int rc = 0;

  	spin_lock_irqsave(&info->lock, flags);

  
  	if (info->pending_bh & BH_RECEIVE) {
  		info->pending_bh &= ~BH_RECEIVE;
  		rc = BH_RECEIVE;
  	} else if (info->pending_bh & BH_TRANSMIT) {
  		info->pending_bh &= ~BH_TRANSMIT;
  		rc = BH_TRANSMIT;
  	} else if (info->pending_bh & BH_STATUS) {
  		info->pending_bh &= ~BH_STATUS;
  		rc = BH_STATUS;
  	}
  
  	if (!rc) {
  		/* Mark BH routine as complete */

  		info->bh_running = false;
  		info->bh_requested = false;

  	}

  	spin_unlock_irqrestore(&info->lock, flags);

  	return rc;
  }

  static void bh_handler(struct work_struct *work)

  {

  	MGSLPC_INFO *info = container_of(work, MGSLPC_INFO, task);

  	struct tty_struct *tty;

  	int action;

  	if (debug_level >= DEBUG_LEVEL_BH)

  		printk("%s(%d):bh_handler(%s) entry
  ",

  			__FILE__,__LINE__,info->device_name);

  	info->bh_running = true;

  	tty = tty_port_tty_get(&info->port);

  
  	while((action = bh_action(info)) != 0) {

  		/* Process work item */

  		if (debug_level >= DEBUG_LEVEL_BH)
  			printk("%s(%d):bh_handler() work item action=%d
  ",

  				__FILE__,__LINE__,action);
  
  		switch (action) {

  		case BH_RECEIVE:

  			while(rx_get_frame(info, tty));

  			break;
  		case BH_TRANSMIT:

  			bh_transmit(info, tty);

  			break;
  		case BH_STATUS:
  			bh_status(info);
  			break;
  		default:
  			/* unknown work item ID */
  			printk("Unknown work item ID=%08X!
  ", action);
  			break;
  		}
  	}

  	tty_kref_put(tty);

  	if (debug_level >= DEBUG_LEVEL_BH)

  		printk("%s(%d):bh_handler(%s) exit
  ",

  			__FILE__,__LINE__,info->device_name);
  }

  static void bh_transmit(MGSLPC_INFO *info, struct tty_struct *tty)

  {

  	if (debug_level >= DEBUG_LEVEL_BH)
  		printk("bh_transmit() entry on %s
  ", info->device_name);

  	if (tty)

  		tty_wakeup(tty);

  }

  static void bh_status(MGSLPC_INFO *info)

  {
  	info->ri_chkcount = 0;
  	info->dsr_chkcount = 0;
  	info->dcd_chkcount = 0;
  	info->cts_chkcount = 0;
  }

  /* eom: non-zero = end of frame */

  static void rx_ready_hdlc(MGSLPC_INFO *info, int eom)
  {
  	unsigned char data[2];
  	unsigned char fifo_count, read_count, i;
  	RXBUF *buf = (RXBUF*)(info->rx_buf + (info->rx_put * info->rx_buf_size));
  
  	if (debug_level >= DEBUG_LEVEL_ISR)

  		printk("%s(%d):rx_ready_hdlc(eom=%d)
  ", __FILE__, __LINE__, eom);

  	if (!info->rx_enabled)
  		return;
  
  	if (info->rx_frame_count >= info->rx_buf_count) {
  		/* no more free buffers */
  		issue_command(info, CHA, CMD_RXRESET);
  		info->pending_bh |= BH_RECEIVE;

  		info->rx_overflow = true;

  		info->icount.buf_overrun++;
  		return;
  	}
  
  	if (eom) {

  		/* end of frame, get FIFO count from RBCL register */

  		fifo_count = (unsigned char)(read_reg(info, CHA+RBCL) & 0x1f);
  		if (fifo_count == 0)

  			fifo_count = 32;
  	} else
  		fifo_count = 32;

  	do {
  		if (fifo_count == 1) {
  			read_count = 1;
  			data[0] = read_reg(info, CHA + RXFIFO);
  		} else {
  			read_count = 2;
  			*((unsigned short *) data) = read_reg16(info, CHA + RXFIFO);
  		}
  		fifo_count -= read_count;
  		if (!fifo_count && eom)
  			buf->status = data[--read_count];
  
  		for (i = 0; i < read_count; i++) {
  			if (buf->count >= info->max_frame_size) {
  				/* frame too large, reset receiver and reset current buffer */
  				issue_command(info, CHA, CMD_RXRESET);
  				buf->count = 0;
  				return;
  			}
  			*(buf->data + buf->count) = data[i];
  			buf->count++;
  		}
  	} while (fifo_count);
  
  	if (eom) {
  		info->pending_bh |= BH_RECEIVE;
  		info->rx_frame_count++;
  		info->rx_put++;
  		if (info->rx_put >= info->rx_buf_count)
  			info->rx_put = 0;
  	}
  	issue_command(info, CHA, CMD_RXFIFO);
  }

  static void rx_ready_async(MGSLPC_INFO *info, int tcd)

  {

  	struct tty_port *port = &info->port;

  	unsigned char data, status, flag;

  	int fifo_count;

  	int work = 0;

  	struct mgsl_icount *icount = &info->icount;

  
  	if (tcd) {

  		/* early termination, get FIFO count from RBCL register */

  		fifo_count = (unsigned char)(read_reg(info, CHA+RBCL) & 0x1f);
  
  		/* Zero fifo count could mean 0 or 32 bytes available.
  		 * If BIT5 of STAR is set then at least 1 byte is available.
  		 */
  		if (!fifo_count && (read_reg(info,CHA+STAR) & BIT5))
  			fifo_count = 32;
  	} else
  		fifo_count = 32;

  	tty_buffer_request_room(port, fifo_count);

  	/* Flush received async data to receive data buffer. */

  	while (fifo_count) {
  		data   = read_reg(info, CHA + RXFIFO);
  		status = read_reg(info, CHA + RXFIFO);
  		fifo_count -= 2;

  		icount->rx++;

  		flag = TTY_NORMAL;

  
  		// if no frameing/crc error then save data
  		// BIT7:parity error
  		// BIT6:framing error
  
  		if (status & (BIT7 + BIT6)) {

  			if (status & BIT7)

  				icount->parity++;
  			else
  				icount->frame++;
  
  			/* discard char if tty control flags say so */
  			if (status & info->ignore_status_mask)
  				continue;

  			status &= info->read_status_mask;
  
  			if (status & BIT7)

  				flag = TTY_PARITY;

  			else if (status & BIT6)

  				flag = TTY_FRAME;

  		}

  		work += tty_insert_flip_char(port, data, flag);

  	}
  	issue_command(info, CHA, CMD_RXFIFO);
  
  	if (debug_level >= DEBUG_LEVEL_ISR) {

  		printk("%s(%d):rx_ready_async",
  			__FILE__,__LINE__);

  		printk("%s(%d):rx=%d brk=%d parity=%d frame=%d overrun=%d
  ",
  			__FILE__,__LINE__,icount->rx,icount->brk,
  			icount->parity,icount->frame,icount->overrun);
  	}

  	if (work)

  		tty_flip_buffer_push(port);

  }

  static void tx_done(MGSLPC_INFO *info, struct tty_struct *tty)

  {
  	if (!info->tx_active)
  		return;

  	info->tx_active = false;
  	info->tx_aborting = false;

  
  	if (info->params.mode == MGSL_MODE_ASYNC)
  		return;
  
  	info->tx_count = info->tx_put = info->tx_get = 0;

  	del_timer(&info->tx_timer);

  	if (info->drop_rts_on_tx_done) {
  		get_signals(info);
  		if (info->serial_signals & SerialSignal_RTS) {
  			info->serial_signals &= ~SerialSignal_RTS;
  			set_signals(info);
  		}

  		info->drop_rts_on_tx_done = false;

  	}

  #if SYNCLINK_GENERIC_HDLC

  	if (info->netcount)
  		hdlcdev_tx_done(info);

  	else

  #endif
  	{

  		if (tty && (tty->stopped || tty->hw_stopped)) {

  			tx_stop(info);
  			return;
  		}
  		info->pending_bh |= BH_TRANSMIT;
  	}
  }

  static void tx_ready(MGSLPC_INFO *info, struct tty_struct *tty)

  {
  	unsigned char fifo_count = 32;
  	int c;
  
  	if (debug_level >= DEBUG_LEVEL_ISR)

  		printk("%s(%d):tx_ready(%s)
  ", __FILE__, __LINE__, info->device_name);

  
  	if (info->params.mode == MGSL_MODE_HDLC) {
  		if (!info->tx_active)
  			return;
  	} else {

  		if (tty && (tty->stopped || tty->hw_stopped)) {

  			tx_stop(info);
  			return;
  		}
  		if (!info->tx_count)

  			info->tx_active = false;

  	}
  
  	if (!info->tx_count)
  		return;
  
  	while (info->tx_count && fifo_count) {
  		c = min(2, min_t(int, fifo_count, min(info->tx_count, TXBUFSIZE - info->tx_get)));

  		if (c == 1) {
  			write_reg(info, CHA + TXFIFO, *(info->tx_buf + info->tx_get));
  		} else {
  			write_reg16(info, CHA + TXFIFO,
  					  *((unsigned short*)(info->tx_buf + info->tx_get)));
  		}
  		info->tx_count -= c;
  		info->tx_get = (info->tx_get + c) & (TXBUFSIZE - 1);
  		fifo_count -= c;
  	}
  
  	if (info->params.mode == MGSL_MODE_ASYNC) {
  		if (info->tx_count < WAKEUP_CHARS)
  			info->pending_bh |= BH_TRANSMIT;
  		issue_command(info, CHA, CMD_TXFIFO);
  	} else {
  		if (info->tx_count)
  			issue_command(info, CHA, CMD_TXFIFO);
  		else
  			issue_command(info, CHA, CMD_TXFIFO + CMD_TXEOM);
  	}
  }

  static void cts_change(MGSLPC_INFO *info, struct tty_struct *tty)

  {
  	get_signals(info);
  	if ((info->cts_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
  		irq_disable(info, CHB, IRQ_CTS);
  	info->icount.cts++;
  	if (info->serial_signals & SerialSignal_CTS)
  		info->input_signal_events.cts_up++;
  	else
  		info->input_signal_events.cts_down++;
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);

  	if (tty && tty_port_cts_enabled(&info->port)) {

  		if (tty->hw_stopped) {

  			if (info->serial_signals & SerialSignal_CTS) {
  				if (debug_level >= DEBUG_LEVEL_ISR)
  					printk("CTS tx start...");

  				tty->hw_stopped = 0;

  				tx_start(info, tty);

  				info->pending_bh |= BH_TRANSMIT;
  				return;
  			}
  		} else {
  			if (!(info->serial_signals & SerialSignal_CTS)) {
  				if (debug_level >= DEBUG_LEVEL_ISR)
  					printk("CTS tx stop...");

  				tty->hw_stopped = 1;

  				tx_stop(info);
  			}
  		}
  	}
  	info->pending_bh |= BH_STATUS;
  }

  static void dcd_change(MGSLPC_INFO *info, struct tty_struct *tty)

  {
  	get_signals(info);
  	if ((info->dcd_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
  		irq_disable(info, CHB, IRQ_DCD);
  	info->icount.dcd++;
  	if (info->serial_signals & SerialSignal_DCD) {
  		info->input_signal_events.dcd_up++;
  	}
  	else
  		info->input_signal_events.dcd_down++;

  #if SYNCLINK_GENERIC_HDLC

  	if (info->netcount) {
  		if (info->serial_signals & SerialSignal_DCD)
  			netif_carrier_on(info->netdev);
  		else
  			netif_carrier_off(info->netdev);
  	}

  #endif
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);

  	if (tty_port_check_carrier(&info->port)) {

  		if (debug_level >= DEBUG_LEVEL_ISR)
  			printk("%s CD now %s...", info->device_name,
  			       (info->serial_signals & SerialSignal_DCD) ? "on" : "off");
  		if (info->serial_signals & SerialSignal_DCD)

  			wake_up_interruptible(&info->port.open_wait);

  		else {
  			if (debug_level >= DEBUG_LEVEL_ISR)
  				printk("doing serial hangup...");

  			if (tty)
  				tty_hangup(tty);

  		}
  	}
  	info->pending_bh |= BH_STATUS;
  }
  
  static void dsr_change(MGSLPC_INFO *info)
  {
  	get_signals(info);
  	if ((info->dsr_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
  		port_irq_disable(info, PVR_DSR);
  	info->icount.dsr++;
  	if (info->serial_signals & SerialSignal_DSR)
  		info->input_signal_events.dsr_up++;
  	else
  		info->input_signal_events.dsr_down++;
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  	info->pending_bh |= BH_STATUS;
  }
  
  static void ri_change(MGSLPC_INFO *info)
  {
  	get_signals(info);
  	if ((info->ri_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
  		port_irq_disable(info, PVR_RI);
  	info->icount.rng++;
  	if (info->serial_signals & SerialSignal_RI)
  		info->input_signal_events.ri_up++;
  	else
  		info->input_signal_events.ri_down++;
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);
  	info->pending_bh |= BH_STATUS;
  }
  
  /* Interrupt service routine entry point.

   *

   * Arguments:

   *

   * irq     interrupt number that caused interrupt
   * dev_id  device ID supplied during interrupt registration

   */

  static irqreturn_t mgslpc_isr(int dummy, void *dev_id)

  {

  	MGSLPC_INFO *info = dev_id;

  	struct tty_struct *tty;

  	unsigned short isr;
  	unsigned char gis, pis;
  	int count=0;

  	if (debug_level >= DEBUG_LEVEL_ISR)

  		printk("mgslpc_isr(%d) entry.
  ", info->irq_level);

  	if (!(info->p_dev->_locked))

  		return IRQ_HANDLED;

  	tty = tty_port_tty_get(&info->port);

  	spin_lock(&info->lock);
  
  	while ((gis = read_reg(info, CHA + GIS))) {

  		if (debug_level >= DEBUG_LEVEL_ISR)

  			printk("mgslpc_isr %s gis=%04X
  ", info->device_name,gis);
  
  		if ((gis & 0x70) || count > 1000) {
  			printk("synclink_cs:hardware failed or ejected
  ");
  			break;
  		}
  		count++;

  		if (gis & (BIT1 | BIT0)) {

  			isr = read_reg16(info, CHB + ISR);
  			if (isr & IRQ_DCD)

  				dcd_change(info, tty);

  			if (isr & IRQ_CTS)

  				cts_change(info, tty);

  		}

  		if (gis & (BIT3 | BIT2))

  		{
  			isr = read_reg16(info, CHA + ISR);
  			if (isr & IRQ_TIMER) {

  				info->irq_occurred = true;

  				irq_disable(info, CHA, IRQ_TIMER);
  			}

  			/* receive IRQs */

  			if (isr & IRQ_EXITHUNT) {
  				info->icount.exithunt++;
  				wake_up_interruptible(&info->event_wait_q);
  			}
  			if (isr & IRQ_BREAK_ON) {
  				info->icount.brk++;

  				if (info->port.flags & ASYNC_SAK)
  					do_SAK(tty);

  			}
  			if (isr & IRQ_RXTIME) {
  				issue_command(info, CHA, CMD_RXFIFO_READ);
  			}

  			if (isr & (IRQ_RXEOM | IRQ_RXFIFO)) {

  				if (info->params.mode == MGSL_MODE_HDLC)

  					rx_ready_hdlc(info, isr & IRQ_RXEOM);

  				else

  					rx_ready_async(info, isr & IRQ_RXEOM);

  			}

  			/* transmit IRQs */

  			if (isr & IRQ_UNDERRUN) {
  				if (info->tx_aborting)
  					info->icount.txabort++;
  				else
  					info->icount.txunder++;

  				tx_done(info, tty);

  			}
  			else if (isr & IRQ_ALLSENT) {
  				info->icount.txok++;

  				tx_done(info, tty);

  			}
  			else if (isr & IRQ_TXFIFO)

  				tx_ready(info, tty);

  		}
  		if (gis & BIT7) {
  			pis = read_reg(info, CHA + PIS);
  			if (pis & BIT1)
  				dsr_change(info);
  			if (pis & BIT2)
  				ri_change(info);
  		}
  	}

  
  	/* Request bottom half processing if there's something

  	 * for it to do and the bh is not already running
  	 */
  
  	if (info->pending_bh && !info->bh_running && !info->bh_requested) {

  		if (debug_level >= DEBUG_LEVEL_ISR)

  			printk("%s(%d):%s queueing bh task.
  ",
  				__FILE__,__LINE__,info->device_name);
  		schedule_work(&info->task);

  		info->bh_requested = true;

  	}
  
  	spin_unlock(&info->lock);

  	tty_kref_put(tty);

  
  	if (debug_level >= DEBUG_LEVEL_ISR)

  		printk("%s(%d):mgslpc_isr(%d)exit.
  ",

  		       __FILE__, __LINE__, info->irq_level);

  
  	return IRQ_HANDLED;
  }
  
  /* Initialize and start device.
   */

  static int startup(MGSLPC_INFO * info, struct tty_struct *tty)

  {
  	int retval = 0;

  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("%s(%d):startup(%s)
  ", __FILE__, __LINE__, info->device_name);

  	if (tty_port_initialized(&info->port))

  		return 0;

  	if (!info->tx_buf) {
  		/* allocate a page of memory for a transmit buffer */
  		info->tx_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
  		if (!info->tx_buf) {
  			printk(KERN_ERR"%s(%d):%s can't allocate transmit buffer
  ",

  				__FILE__, __LINE__, info->device_name);

  			return -ENOMEM;
  		}
  	}
  
  	info->pending_bh = 0;

  	memset(&info->icount, 0, sizeof(info->icount));

  	setup_timer(&info->tx_timer, tx_timeout, (unsigned long)info);

  
  	/* Allocate and claim adapter resources */
  	retval = claim_resources(info);

  	/* perform existence check and diagnostics */

  	if (!retval)

  		retval = adapter_test(info);

  	if (retval) {
  		if (capable(CAP_SYS_ADMIN) && tty)

  			set_bit(TTY_IO_ERROR, &tty->flags);

  		release_resources(info);

  		return retval;
  	}

  
  	/* program hardware for current parameters */

  	mgslpc_change_params(info, tty);

  	if (tty)
  		clear_bit(TTY_IO_ERROR, &tty->flags);

  	tty_port_set_initialized(&info->port, 1);

  	return 0;
  }
  
  /* Called by mgslpc_close() and mgslpc_hangup() to shutdown hardware
   */

  static void shutdown(MGSLPC_INFO * info, struct tty_struct *tty)

  {
  	unsigned long flags;

  	if (!tty_port_initialized(&info->port))

  		return;
  
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_shutdown(%s)
  ",

  			 __FILE__, __LINE__, info->device_name);

  
  	/* clear status wait queue because status changes */
  	/* can't happen after shutting down the hardware */
  	wake_up_interruptible(&info->status_event_wait_q);
  	wake_up_interruptible(&info->event_wait_q);

  	del_timer_sync(&info->tx_timer);

  
  	if (info->tx_buf) {
  		free_page((unsigned long) info->tx_buf);
  		info->tx_buf = NULL;
  	}

  	spin_lock_irqsave(&info->lock, flags);

  
  	rx_stop(info);
  	tx_stop(info);
  
  	/* TODO:disable interrupts instead of reset to preserve signal states */
  	reset_device(info);

  	if (!tty || C_HUPCL(tty)) {

  		info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);

  		set_signals(info);
  	}

  	spin_unlock_irqrestore(&info->lock, flags);

  	release_resources(info);

  	if (tty)
  		set_bit(TTY_IO_ERROR, &tty->flags);

  	tty_port_set_initialized(&info->port, 0);

  }

  static void mgslpc_program_hw(MGSLPC_INFO *info, struct tty_struct *tty)

  {
  	unsigned long flags;

  	spin_lock_irqsave(&info->lock, flags);

  	rx_stop(info);
  	tx_stop(info);
  	info->tx_count = info->tx_put = info->tx_get = 0;

  	if (info->params.mode == MGSL_MODE_HDLC || info->netcount)
  		hdlc_mode(info);
  	else
  		async_mode(info);

  	set_signals(info);

  	info->dcd_chkcount = 0;
  	info->cts_chkcount = 0;
  	info->ri_chkcount = 0;
  	info->dsr_chkcount = 0;
  
  	irq_enable(info, CHB, IRQ_DCD | IRQ_CTS);
  	port_irq_enable(info, (unsigned char) PVR_DSR | PVR_RI);
  	get_signals(info);

  	if (info->netcount || (tty && C_CREAD(tty)))

  		rx_start(info);

  	spin_unlock_irqrestore(&info->lock, flags);

  }
  
  /* Reconfigure adapter based on new parameters
   */

  static void mgslpc_change_params(MGSLPC_INFO *info, struct tty_struct *tty)

  {
  	unsigned cflag;
  	int bits_per_char;

  	if (!tty)

  		return;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_change_params(%s)
  ",

  			 __FILE__, __LINE__, info->device_name);

  	cflag = tty->termios.c_cflag;

  	/* if B0 rate (hangup) specified then negate RTS and DTR */
  	/* otherwise assert RTS and DTR */

  	if (cflag & CBAUD)

  		info->serial_signals |= SerialSignal_RTS | SerialSignal_DTR;

  	else

  		info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);

  	/* byte size and parity */

  	switch (cflag & CSIZE) {
  	case CS5: info->params.data_bits = 5; break;
  	case CS6: info->params.data_bits = 6; break;
  	case CS7: info->params.data_bits = 7; break;
  	case CS8: info->params.data_bits = 8; break;
  	default:  info->params.data_bits = 7; break;
  	}

  	if (cflag & CSTOPB)
  		info->params.stop_bits = 2;
  	else
  		info->params.stop_bits = 1;
  
  	info->params.parity = ASYNC_PARITY_NONE;
  	if (cflag & PARENB) {
  		if (cflag & PARODD)
  			info->params.parity = ASYNC_PARITY_ODD;
  		else
  			info->params.parity = ASYNC_PARITY_EVEN;
  #ifdef CMSPAR
  		if (cflag & CMSPAR)
  			info->params.parity = ASYNC_PARITY_SPACE;
  #endif
  	}
  
  	/* calculate number of jiffies to transmit a full
  	 * FIFO (32 bytes) at specified data rate
  	 */

  	bits_per_char = info->params.data_bits +

  			info->params.stop_bits + 1;
  
  	/* if port data rate is set to 460800 or less then
  	 * allow tty settings to override, otherwise keep the
  	 * current data rate.
  	 */
  	if (info->params.data_rate <= 460800) {

  		info->params.data_rate = tty_get_baud_rate(tty);

  	}

  	if (info->params.data_rate) {

  		info->timeout = (32*HZ*bits_per_char) /

  				info->params.data_rate;
  	}
  	info->timeout += HZ/50;		/* Add .02 seconds of slop */

  	tty_port_set_cts_flow(&info->port, cflag & CRTSCTS);

  	tty_port_set_check_carrier(&info->port, ~cflag & CLOCAL);

  
  	/* process tty input control flags */

  	info->read_status_mask = 0;

  	if (I_INPCK(tty))

  		info->read_status_mask |= BIT7 | BIT6;

  	if (I_IGNPAR(tty))

  		info->ignore_status_mask |= BIT7 | BIT6;

  	mgslpc_program_hw(info, tty);

  }
  
  /* Add a character to the transmit buffer
   */

  static int mgslpc_put_char(struct tty_struct *tty, unsigned char ch)

  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;
  
  	if (debug_level >= DEBUG_LEVEL_INFO) {

  		printk("%s(%d):mgslpc_put_char(%d) on %s
  ",
  			__FILE__, __LINE__, ch, info->device_name);

  	}
  
  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_put_char"))

  		return 0;

  	if (!info->tx_buf)

  		return 0;

  	spin_lock_irqsave(&info->lock, flags);

  	if (info->params.mode == MGSL_MODE_ASYNC || !info->tx_active) {
  		if (info->tx_count < TXBUFSIZE - 1) {
  			info->tx_buf[info->tx_put++] = ch;
  			info->tx_put &= TXBUFSIZE-1;
  			info->tx_count++;
  		}
  	}

  	spin_unlock_irqrestore(&info->lock, flags);

  	return 1;

  }
  
  /* Enable transmitter so remaining characters in the
   * transmit buffer are sent.
   */
  static void mgslpc_flush_chars(struct tty_struct *tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("%s(%d):mgslpc_flush_chars() entry on %s tx_count=%d
  ",
  			__FILE__, __LINE__, info->device_name, info->tx_count);

  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_flush_chars"))
  		return;
  
  	if (info->tx_count <= 0 || tty->stopped ||
  	    tty->hw_stopped || !info->tx_buf)
  		return;
  
  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("%s(%d):mgslpc_flush_chars() entry on %s starting transmitter
  ",
  			__FILE__, __LINE__, info->device_name);

  	spin_lock_irqsave(&info->lock, flags);

  	if (!info->tx_active)

  		tx_start(info, tty);
  	spin_unlock_irqrestore(&info->lock, flags);

  }
  
  /* Send a block of data

   *

   * Arguments:

   *

   * tty        pointer to tty information structure
   * buf	      pointer to buffer containing send data
   * count      size of send data in bytes

   *

   * Returns: number of characters written
   */
  static int mgslpc_write(struct tty_struct * tty,
  			const unsigned char *buf, int count)
  {
  	int c, ret = 0;
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("%s(%d):mgslpc_write(%s) count=%d
  ",
  			__FILE__, __LINE__, info->device_name, count);

  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_write") ||

  		!info->tx_buf)

  		goto cleanup;
  
  	if (info->params.mode == MGSL_MODE_HDLC) {
  		if (count > TXBUFSIZE) {
  			ret = -EIO;
  			goto cleanup;
  		}
  		if (info->tx_active)
  			goto cleanup;
  		else if (info->tx_count)
  			goto start;
  	}
  
  	for (;;) {
  		c = min(count,
  			min(TXBUFSIZE - info->tx_count - 1,
  			    TXBUFSIZE - info->tx_put));
  		if (c <= 0)
  			break;

  		memcpy(info->tx_buf + info->tx_put, buf, c);

  		spin_lock_irqsave(&info->lock, flags);

  		info->tx_put = (info->tx_put + c) & (TXBUFSIZE-1);
  		info->tx_count += c;

  		spin_unlock_irqrestore(&info->lock, flags);

  
  		buf += c;
  		count -= c;
  		ret += c;
  	}
  start:

  	if (info->tx_count && !tty->stopped && !tty->hw_stopped) {
  		spin_lock_irqsave(&info->lock, flags);

  		if (!info->tx_active)

  			tx_start(info, tty);
  		spin_unlock_irqrestore(&info->lock, flags);
  	}

  cleanup:

  	if (debug_level >= DEBUG_LEVEL_INFO)

  		printk("%s(%d):mgslpc_write(%s) returning=%d
  ",
  			__FILE__, __LINE__, info->device_name, ret);

  	return ret;
  }
  
  /* Return the count of free bytes in transmit buffer
   */
  static int mgslpc_write_room(struct tty_struct *tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	int ret;

  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_write_room"))
  		return 0;
  
  	if (info->params.mode == MGSL_MODE_HDLC) {
  		/* HDLC (frame oriented) mode */
  		if (info->tx_active)
  			return 0;
  		else
  			return HDLC_MAX_FRAME_SIZE;
  	} else {
  		ret = TXBUFSIZE - info->tx_count - 1;
  		if (ret < 0)
  			ret = 0;
  	}

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_write_room(%s)=%d
  ",

  			 __FILE__, __LINE__, info->device_name, ret);

  	return ret;
  }
  
  /* Return the count of bytes in transmit buffer
   */
  static int mgslpc_chars_in_buffer(struct tty_struct *tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	int rc;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_chars_in_buffer(%s)
  ",

  			 __FILE__, __LINE__, info->device_name);

  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_chars_in_buffer"))
  		return 0;

  	if (info->params.mode == MGSL_MODE_HDLC)
  		rc = info->tx_active ? info->max_frame_size : 0;
  	else
  		rc = info->tx_count;
  
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_chars_in_buffer(%s)=%d
  ",

  			 __FILE__, __LINE__, info->device_name, rc);

  	return rc;
  }
  
  /* Discard all data in the send buffer
   */
  static void mgslpc_flush_buffer(struct tty_struct *tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_flush_buffer(%s) entry
  ",

  			 __FILE__, __LINE__, info->device_name);

  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_flush_buffer"))
  		return;

  	spin_lock_irqsave(&info->lock, flags);

  	info->tx_count = info->tx_put = info->tx_get = 0;

  	del_timer(&info->tx_timer);

  	spin_unlock_irqrestore(&info->lock, flags);

  
  	wake_up_interruptible(&tty->write_wait);
  	tty_wakeup(tty);
  }
  
  /* Send a high-priority XON/XOFF character
   */
  static void mgslpc_send_xchar(struct tty_struct *tty, char ch)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;
  
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_send_xchar(%s,%d)
  ",

  			 __FILE__, __LINE__, info->device_name, ch);

  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_send_xchar"))
  		return;
  
  	info->x_char = ch;
  	if (ch) {

  		spin_lock_irqsave(&info->lock, flags);

  		if (!info->tx_enabled)

  			tx_start(info, tty);
  		spin_unlock_irqrestore(&info->lock, flags);

  	}
  }
  
  /* Signal remote device to throttle send data (our receive data)
   */
  static void mgslpc_throttle(struct tty_struct * tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_throttle(%s) entry
  ",

  			 __FILE__, __LINE__, info->device_name);

  
  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_throttle"))
  		return;

  	if (I_IXOFF(tty))
  		mgslpc_send_xchar(tty, STOP_CHAR(tty));

  	if (C_CRTSCTS(tty)) {

  		spin_lock_irqsave(&info->lock, flags);

  		info->serial_signals &= ~SerialSignal_RTS;

  		set_signals(info);
  		spin_unlock_irqrestore(&info->lock, flags);

  	}
  }
  
  /* Signal remote device to stop throttling send data (our receive data)
   */
  static void mgslpc_unthrottle(struct tty_struct * tty)
  {
  	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
  	unsigned long flags;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):mgslpc_unthrottle(%s) entry
  ",

  			 __FILE__, __LINE__, info->device_name);

  
  	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_unthrottle"))
  		return;

  	if (I_IXOFF(tty)) {
  		if (info->x_char)
  			info->x_char = 0;
  		else
  			mgslpc_send_xchar(tty, START_CHAR(tty));
  	}

  	if (C_CRTSCTS(tty)) {

  		spin_lock_irqsave(&info->lock, flags);

  		info->serial_signals |= SerialSignal_RTS;

  		set_signals(info);
  		spin_unlock_irqrestore(&info->lock, flags);

  	}
  }
  
  /* get the current serial statistics
   */
  static int get_stats(MGSLPC_INFO * info, struct mgsl_icount __user *user_icount)
  {
  	int err;
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("get_params(%s)
  ", info->device_name);

  	if (!user_icount) {
  		memset(&info->icount, 0, sizeof(info->icount));
  	} else {
  		COPY_TO_USER(err, user_icount, &info->icount, sizeof(struct mgsl_icount));
  		if (err)
  			return -EFAULT;
  	}

  	return 0;
  }
  
  /* get the current serial parameters
   */
  static int get_params(MGSLPC_INFO * info, MGSL_PARAMS __user *user_params)
  {
  	int err;
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("get_params(%s)
  ", info->device_name);
  	COPY_TO_USER(err,user_params, &info->params, sizeof(MGSL_PARAMS));
  	if (err)
  		return -EFAULT;
  	return 0;
  }
  
  /* set the serial parameters

   *

   * Arguments:

   *

   *	info		pointer to device instance data
   *	new_params	user buffer containing new serial params

   *
   * Returns:	0 if success, otherwise error code
   */

  static int set_params(MGSLPC_INFO * info, MGSL_PARAMS __user *new_params, struct tty_struct *tty)

  {

  	unsigned long flags;

  	MGSL_PARAMS tmp_params;
  	int err;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("%s(%d):set_params %s
  ", __FILE__,__LINE__,

  			info->device_name);

  	COPY_FROM_USER(err,&tmp_params, new_params, sizeof(MGSL_PARAMS));
  	if (err) {

  		if (debug_level >= DEBUG_LEVEL_INFO)
  			printk("%s(%d):set_params(%s) user buffer copy failed
  ",
  				__FILE__, __LINE__, info->device_name);

  		return -EFAULT;
  	}

  	spin_lock_irqsave(&info->lock, flags);

  	memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));

  	spin_unlock_irqrestore(&info->lock, flags);

  	mgslpc_change_params(info, tty);

  	return 0;
  }
  
  static int get_txidle(MGSLPC_INFO * info, int __user *idle_mode)
  {
  	int err;
  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("get_txidle(%s)=%d
  ", info->device_name, info->idle_mode);
  	COPY_TO_USER(err,idle_mode, &info->idle_mode, sizeof(int));
  	if (err)
  		return -EFAULT;
  	return 0;
  }
  
  static int set_txidle(MGSLPC_INFO * info, int idle_mode)
  {

  	unsigned long flags;

  	if (debug_level >= DEBUG_LEVEL_INFO)
  		printk("set_txidle(%s,%d)
  ", info->device_name, idle_mode);

  	spin_lock_irqsave(&info->lock, flags);