/*
 * $Id: synclinkmp.c,v 4.38 2005/07/15 13:29:44 paulkf Exp $
 *
 * Device driver for Microgate SyncLink Multiport
 * high speed multiprotocol serial adapter.
 *
 * written by Paul Fulghum for Microgate Corporation
 * paulkf@microgate.com
 *
 * Microgate and SyncLink are trademarks of Microgate Corporation
 *
 * Derived from serial.c written by Theodore Ts'o and Linus Torvalds
 * 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_DEVICES 12

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

#if defined(CONFIG_HDLC) || (defined(CONFIG_HDLC_MODULE) && defined(CONFIG_SYNCLINKMP_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; */
};

/* size in bytes of DMA data buffers */
#define SCABUFSIZE      1024
#define SCA_MEM_SIZE    0x40000
#define SCA_BASE_SIZE   512
#define SCA_REG_SIZE    16
#define SCA_MAX_PORTS   4
#define SCAMAXDESC      128

#define BUFFERLISTSIZE  4096

/* SCA-I style DMA buffer descriptor */
typedef struct _SCADESC
{
        u16     next;           /* lower l6 bits of next descriptor addr */
        u16     buf_ptr;        /* lower 16 bits of buffer addr */
        u8      buf_base;       /* upper 8 bits of buffer addr */
        u8      pad1;
        u16     length;         /* length of buffer */
        u8      status;         /* status of buffer */
        u8      pad2;
} SCADESC, *PSCADESC;

typedef struct _SCADESC_EX
{
        /* device driver bookkeeping section */
        char    *virt_addr;     /* virtual address of data buffer */
        u16     phys_entry;     /* lower 16-bits of physical address of this descriptor */
} SCADESC_EX, *PSCADESC_EX;

/* 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

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 _synclinkmp_info {
        void *if_ptr;                           /* General purpose pointer (used by SPPP) */
        int                     magic;
        struct tty_port         port;
        int                     line;
        unsigned short          close_delay;
        unsigned short          closing_wait;   /* time to wait before closing */

        struct mgsl_icount      icount;

        int                     timeout;
        int                     x_char;         /* xon/xoff character */
        u16                     read_status_mask1;  /* break detection (SR1 indications) */
        u16                     read_status_mask2;  /* parity/framing/overun (SR2 indications) */
        unsigned char           ignore_status_mask1;  /* break detection (SR1 indications) */
        unsigned char           ignore_status_mask2;  /* parity/framing/overun (SR2 indications) */
        unsigned char           *tx_buf;
        int                     tx_put;
        int                     tx_get;
        int                     tx_count;

        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 _synclinkmp_info *next_device;   /* device list link */
        struct timer_list       status_timer;   /* input signal status check timer */

        spinlock_t lock;                /* spinlock for synchronizing with ISR */
        struct work_struct task;                        /* task structure for scheduling bh */

        u32 max_frame_size;                     /* as set by device config */

        u32 pending_bh;

        bool bh_running;                                /* Protection from multiple */
        int isr_overflow;
        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;

        char *buffer_list;                      /* virtual address of Rx & Tx buffer lists */
        unsigned long buffer_list_phys;

        unsigned int rx_buf_count;              /* count of total allocated Rx buffers */
        SCADESC *rx_buf_list;                   /* list of receive buffer entries */
        SCADESC_EX rx_buf_list_ex[SCAMAXDESC]; /* list of receive buffer entries */
        unsigned int current_rx_buf;

        unsigned int tx_buf_count;              /* count of total allocated Tx buffers */
        SCADESC *tx_buf_list;           /* list of transmit buffer entries */
        SCADESC_EX tx_buf_list_ex[SCAMAXDESC]; /* list of transmit buffer entries */
        unsigned int last_tx_buf;

        unsigned char *tmp_rx_buf;
        unsigned int tmp_rx_buf_count;

        bool rx_enabled;
        bool rx_overflow;

        bool tx_enabled;
        bool tx_active;
        u32 idle_mode;

        unsigned char ie0_value;
        unsigned char ie1_value;
        unsigned char ie2_value;
        unsigned char ctrlreg_value;
        unsigned char old_signals;

        char device_name[25];                   /* device instance name */

        int port_count;
        int adapter_num;
        int port_num;

        struct _synclinkmp_info *port_array[SCA_MAX_PORTS];

        unsigned int bus_type;                  /* expansion bus type (ISA,EISA,PCI) */

        unsigned int irq_level;                 /* interrupt level */
        unsigned long irq_flags;
        bool irq_requested;                     /* true if IRQ requested */

        MGSL_PARAMS params;                     /* communications parameters */

        unsigned char serial_signals;           /* current serial signal states */

        bool irq_occurred;                      /* for diagnostics use */
        unsigned int init_error;                /* Initialization startup error */

        u32 last_mem_alloc;
        unsigned char* memory_base;             /* shared memory address (PCI only) */
        u32 phys_memory_base;
        int shared_mem_requested;

        unsigned char* sca_base;                /* HD64570 SCA Memory address */
        u32 phys_sca_base;
        u32 sca_offset;
        bool sca_base_requested;

        unsigned char* lcr_base;                /* local config registers (PCI only) */
        u32 phys_lcr_base;
        u32 lcr_offset;
        int lcr_mem_requested;

        unsigned char* statctrl_base;           /* status/control register memory */
        u32 phys_statctrl_base;
        u32 statctrl_offset;
        bool sca_statctrl_requested;

        u32 misc_ctrl_value;
        char *flag_buf;
        bool drop_rts_on_tx_done;

        struct  _input_signal_events    input_signal_events;

        /* SPPP/Cisco HDLC device parts */
        int netcount;
        spinlock_t netlock;

#if SYNCLINK_GENERIC_HDLC
        struct net_device *netdev;
#endif

} SLMP_INFO;

#define MGSL_MAGIC 0x5401

/*
 * define serial signal status change macros
 */
#define MISCSTATUS_DCD_LATCHED  (SerialSignal_DCD<<8)   /* indicates change in DCD */
#define MISCSTATUS_RI_LATCHED   (SerialSignal_RI<<8)    /* indicates change in RI */
#define MISCSTATUS_CTS_LATCHED  (SerialSignal_CTS<<8)   /* indicates change in CTS */
#define MISCSTATUS_DSR_LATCHED  (SerialSignal_DSR<<8)   /* change in DSR */

/* Common Register macros */
#define LPR     0x00
#define PABR0   0x02
#define PABR1   0x03
#define WCRL    0x04
#define WCRM    0x05
#define WCRH    0x06
#define DPCR    0x08
#define DMER    0x09
#define ISR0    0x10
#define ISR1    0x11
#define ISR2    0x12
#define IER0    0x14
#define IER1    0x15
#define IER2    0x16
#define ITCR    0x18
#define INTVR   0x1a
#define IMVR    0x1c

/* MSCI Register macros */
#define TRB     0x20
#define TRBL    0x20
#define TRBH    0x21
#define SR0     0x22
#define SR1     0x23
#define SR2     0x24
#define SR3     0x25
#define FST     0x26
#define IE0     0x28
#define IE1     0x29
#define IE2     0x2a
#define FIE     0x2b
#define CMD     0x2c
#define MD0     0x2e
#define MD1     0x2f
#define MD2     0x30
#define CTL     0x31
#define SA0     0x32
#define SA1     0x33
#define IDL     0x34
#define TMC     0x35
#define RXS     0x36
#define TXS     0x37
#define TRC0    0x38
#define TRC1    0x39
#define RRC     0x3a
#define CST0    0x3c
#define CST1    0x3d

/* Timer Register Macros */
#define TCNT    0x60
#define TCNTL   0x60
#define TCNTH   0x61
#define TCONR   0x62
#define TCONRL  0x62
#define TCONRH  0x63
#define TMCS    0x64
#define TEPR    0x65

/* DMA Controller Register macros */
#define DARL    0x80
#define DARH    0x81
#define DARB    0x82
#define BAR     0x80
#define BARL    0x80
#define BARH    0x81
#define BARB    0x82
#define SAR     0x84
#define SARL    0x84
#define SARH    0x85
#define SARB    0x86
#define CPB     0x86
#define CDA     0x88
#define CDAL    0x88
#define CDAH    0x89
#define EDA     0x8a
#define EDAL    0x8a
#define EDAH    0x8b
#define BFL     0x8c
#define BFLL    0x8c
#define BFLH    0x8d
#define BCR     0x8e
#define BCRL    0x8e
#define BCRH    0x8f
#define DSR     0x90
#define DMR     0x91
#define FCT     0x93
#define DIR     0x94
#define DCMD    0x95

/* combine with timer or DMA register address */
#define TIMER0  0x00
#define TIMER1  0x08
#define TIMER2  0x10
#define TIMER3  0x18
#define RXDMA   0x00
#define TXDMA   0x20

/* SCA Command Codes */
#define NOOP            0x00
#define TXRESET         0x01
#define TXENABLE        0x02
#define TXDISABLE       0x03
#define TXCRCINIT       0x04
#define TXCRCEXCL       0x05
#define TXEOM           0x06
#define TXABORT         0x07
#define MPON            0x08
#define TXBUFCLR        0x09
#define RXRESET         0x11
#define RXENABLE        0x12
#define RXDISABLE       0x13
#define RXCRCINIT       0x14
#define RXREJECT        0x15
#define SEARCHMP        0x16
#define RXCRCEXCL       0x17
#define RXCRCCALC       0x18
#define CHRESET         0x21
#define HUNT            0x31

/* DMA command codes */
#define SWABORT         0x01
#define FEICLEAR        0x02

/* IE0 */
#define TXINTE          BIT7
#define RXINTE          BIT6
#define TXRDYE          BIT1
#define RXRDYE          BIT0

/* IE1 & SR1 */
#define UDRN    BIT7
#define IDLE    BIT6
#define SYNCD   BIT4
#define FLGD    BIT4
#define CCTS    BIT3
#define CDCD    BIT2
#define BRKD    BIT1
#define ABTD    BIT1
#define GAPD    BIT1
#define BRKE    BIT0
#define IDLD    BIT0

/* IE2 & SR2 */
#define EOM     BIT7
#define PMP     BIT6
#define SHRT    BIT6
#define PE      BIT5
#define ABT     BIT5
#define FRME    BIT4
#define RBIT    BIT4
#define OVRN    BIT3
#define CRCE    BIT2


/*
 * Global linked list of SyncLink devices
 */
static SLMP_INFO *synclinkmp_device_list = NULL;
static int synclinkmp_adapter_count = -1;
static int synclinkmp_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 = 0;

/*
 * Driver major number, defaults to zero to get auto
 * assigned major number. May be forced as module parameter.
 */
static int ttymajor = 0;

/*
 * Array of user specified options for ISA adapters.
 */
static int debug_level = 0;
static int maxframe[MAX_DEVICES] = {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);

static char *driver_name = "SyncLink MultiPort driver";
static char *driver_version = "$Revision: 4.38 $";

static int synclinkmp_init_one(struct pci_dev *dev,const struct pci_device_id *ent);
static void synclinkmp_remove_one(struct pci_dev *dev);

static struct pci_device_id synclinkmp_pci_tbl[] = {
        { PCI_VENDOR_ID_MICROGATE, PCI_DEVICE_ID_MICROGATE_SCA, PCI_ANY_ID, PCI_ANY_ID, },
        { 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, synclinkmp_pci_tbl);

MODULE_LICENSE("GPL");

static struct pci_driver synclinkmp_pci_driver = {
        .name           = "synclinkmp",
        .id_table       = synclinkmp_pci_tbl,
        .probe          = synclinkmp_init_one,
        .remove         = synclinkmp_remove_one,
};


static struct tty_driver *serial_driver;

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256


/* tty callbacks */

static int  open(struct tty_struct *tty, struct file * filp);
static void close(struct tty_struct *tty, struct file * filp);
static void hangup(struct tty_struct *tty);
static void set_termios(struct tty_struct *tty, struct ktermios *old_termios);

static int  write(struct tty_struct *tty, const unsigned char *buf, int count);
static int put_char(struct tty_struct *tty, unsigned char ch);
static void send_xchar(struct tty_struct *tty, char ch);
static void wait_until_sent(struct tty_struct *tty, int timeout);
static int  write_room(struct tty_struct *tty);
static void flush_chars(struct tty_struct *tty);
static void flush_buffer(struct tty_struct *tty);
static void tx_hold(struct tty_struct *tty);
static void tx_release(struct tty_struct *tty);

static int  ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
static int  chars_in_buffer(struct tty_struct *tty);
static void throttle(struct tty_struct * tty);
static void unthrottle(struct tty_struct * tty);
static int set_break(struct tty_struct *tty, int break_state);

#if SYNCLINK_GENERIC_HDLC
#define dev_to_port(D) (dev_to_hdlc(D)->priv)
static void hdlcdev_tx_done(SLMP_INFO *info);
static void hdlcdev_rx(SLMP_INFO *info, char *buf, int size);
static int  hdlcdev_init(SLMP_INFO *info);
static void hdlcdev_exit(SLMP_INFO *info);
#endif

/* ioctl handlers */

static int  get_stats(SLMP_INFO *info, struct mgsl_icount __user *user_icount);
static int  get_params(SLMP_INFO *info, MGSL_PARAMS __user *params);
static int  set_params(SLMP_INFO *info, MGSL_PARAMS __user *params);
static int  get_txidle(SLMP_INFO *info, int __user *idle_mode);
static int  set_txidle(SLMP_INFO *info, int idle_mode);
static int  tx_enable(SLMP_INFO *info, int enable);
static int  tx_abort(SLMP_INFO *info);
static int  rx_enable(SLMP_INFO *info, int enable);
static int  modem_input_wait(SLMP_INFO *info,int arg);
static int  wait_mgsl_event(SLMP_INFO *info, int __user *mask_ptr);
static int  tiocmget(struct tty_struct *tty);
static int  tiocmset(struct tty_struct *tty,
                        unsigned int set, unsigned int clear);
static int  set_break(struct tty_struct *tty, int break_state);

static int  add_device(SLMP_INFO *info);
static int  device_init(int adapter_num, struct pci_dev *pdev);
static int  claim_resources(SLMP_INFO *info);
static void release_resources(SLMP_INFO *info);

static int  startup(SLMP_INFO *info);
static int  block_til_ready(struct tty_struct *tty, struct file * filp,SLMP_INFO *info);
static int carrier_raised(struct tty_port *port);
static void shutdown(SLMP_INFO *info);
static void program_hw(SLMP_INFO *info);
static void change_params(SLMP_INFO *info);

static bool init_adapter(SLMP_INFO *info);
static bool register_test(SLMP_INFO *info);
static bool irq_test(SLMP_INFO *info);
static bool loopback_test(SLMP_INFO *info);
static int  adapter_test(SLMP_INFO *info);
static bool memory_test(SLMP_INFO *info);

static void reset_adapter(SLMP_INFO *info);
static void reset_port(SLMP_INFO *info);
static void async_mode(SLMP_INFO *info);
static void hdlc_mode(SLMP_INFO *info);

static void rx_stop(SLMP_INFO *info);
static void rx_start(SLMP_INFO *info);
static void rx_reset_buffers(SLMP_INFO *info);
static void rx_free_frame_buffers(SLMP_INFO *info, unsigned int first, unsigned int last);
static bool rx_get_frame(SLMP_INFO *info);

static void tx_start(SLMP_INFO *info);
static void tx_stop(SLMP_INFO *info);
static void tx_load_fifo(SLMP_INFO *info);
static void tx_set_idle(SLMP_INFO *info);
static void tx_load_dma_buffer(SLMP_INFO *info, const char *buf, unsigned int count);

static void get_signals(SLMP_INFO *info);
static void set_signals(SLMP_INFO *info);
static void enable_loopback(SLMP_INFO *info, int enable);
static void set_rate(SLMP_INFO *info, u32 data_rate);

static int  bh_action(SLMP_INFO *info);
static void bh_handler(struct work_struct *work);
static void bh_receive(SLMP_INFO *info);
static void bh_transmit(SLMP_INFO *info);
static void bh_status(SLMP_INFO *info);
static void isr_timer(SLMP_INFO *info);
static void isr_rxint(SLMP_INFO *info);
static void isr_rxrdy(SLMP_INFO *info);
static void isr_txint(SLMP_INFO *info);
static void isr_txrdy(SLMP_INFO *info);
static void isr_rxdmaok(SLMP_INFO *info);
static void isr_rxdmaerror(SLMP_INFO *info);
static void isr_txdmaok(SLMP_INFO *info);
static void isr_txdmaerror(SLMP_INFO *info);
static void isr_io_pin(SLMP_INFO *info, u16 status);

static int  alloc_dma_bufs(SLMP_INFO *info);
static void free_dma_bufs(SLMP_INFO *info);
static int  alloc_buf_list(SLMP_INFO *info);
static int  alloc_frame_bufs(SLMP_INFO *info, SCADESC *list, SCADESC_EX *list_ex,int count);
static int  alloc_tmp_rx_buf(SLMP_INFO *info);
static void free_tmp_rx_buf(SLMP_INFO *info);

static void load_pci_memory(SLMP_INFO *info, char* dest, const char* src, unsigned short count);
static void trace_block(SLMP_INFO *info, const char* data, int count, int xmit);
static void tx_timeout(unsigned long context);
static void status_timeout(unsigned long context);

static unsigned char read_reg(SLMP_INFO *info, unsigned char addr);
static void write_reg(SLMP_INFO *info, unsigned char addr, unsigned char val);
static u16 read_reg16(SLMP_INFO *info, unsigned char addr);
static void write_reg16(SLMP_INFO *info, unsigned char addr, u16 val);
static unsigned char read_status_reg(SLMP_INFO * info);
static void write_control_reg(SLMP_INFO * info);


static unsigned char rx_active_fifo_level = 16; // rx request FIFO activation level in bytes
static unsigned char tx_active_fifo_level = 16; // tx request FIFO activation level in bytes
static unsigned char tx_negate_fifo_level = 32; // tx request FIFO negation level in bytes

static u32 misc_ctrl_value = 0x007e4040;
static u32 lcr1_brdr_value = 0x00800028;

static u32 read_ahead_count = 8;

/* DPCR, DMA Priority Control
 *
 * 07..05  Not used, must be 0
 * 04      BRC, bus release condition: 0=all transfers complete
 *              1=release after 1 xfer on all channels
 * 03      CCC, channel change condition: 0=every cycle
 *              1=after each channel completes all xfers
 * 02..00  PR<2..0>, priority 100=round robin
 *
 * 00000100 = 0x00
 */
static unsigned char dma_priority = 0x04;

// Number of bytes that can be written to shared RAM
// in a single write operation
static u32 sca_pci_load_interval = 64;

/*
 * 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* synclinkmp_get_text_ptr(void);
static void* synclinkmp_get_text_ptr(void) {return synclinkmp_get_text_ptr;}

static inline int sanity_check(SLMP_INFO *info,
                               char *name, const char *routine)
{
#ifdef SANITY_CHECK
        static const char *badmagic =
                "Warning: bad magic number for synclinkmp_struct (%s) in %s\n";
        static const char *badinfo =
                "Warning: null synclinkmp_struct for (%s) in %s\n";

        if (!info) {
                printk(badinfo, name, routine);
                return 1;
        }
        if (info->magic != MGSL_MAGIC) {
                printk(badmagic, name, routine);
                return 1;
        }
#else
        if (!info)
                return 1;
#endif
        return 0;
}

/**
 * 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);
        }
}

/* tty callbacks */

static int install(struct tty_driver *driver, struct tty_struct *tty)
{
        SLMP_INFO *info;
        int line = tty->index;

        if (line >= synclinkmp_device_count) {
                printk("%s(%d): open with invalid line #%d.\n",
                        __FILE__,__LINE__,line);
                return -ENODEV;
        }

        info = synclinkmp_device_list;
        while (info && info->line != line)
                info = info->next_device;
        if (sanity_check(info, tty->name, "open"))
                return -ENODEV;
        if (info->init_error) {
                printk("%s(%d):%s device is not allocated, init error=%d\n",
                        __FILE__, __LINE__, info->device_name,
                        info->init_error);
                return -ENODEV;
        }

        tty->driver_data = info;

        return tty_port_install(&info->port, driver, tty);
}

/* Called when a port is opened.  Init and enable port.
 */
static int open(struct tty_struct *tty, struct file *filp)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;
        int retval;

        info->port.tty = tty;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s open(), old ref count = %d\n",
                         __FILE__,__LINE__,tty->driver->name, info->port.count);

        info->port.low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;

        spin_lock_irqsave(&info->netlock, flags);
        if (info->netcount) {
                retval = -EBUSY;
                spin_unlock_irqrestore(&info->netlock, flags);
                goto cleanup;
        }
        info->port.count++;
        spin_unlock_irqrestore(&info->netlock, flags);

        if (info->port.count == 1) {
                /* 1st open on this device, init hardware */
                retval = startup(info);
                if (retval < 0)
                        goto cleanup;
        }

        retval = block_til_ready(tty, filp, info);
        if (retval) {
                if (debug_level >= DEBUG_LEVEL_INFO)
                        printk("%s(%d):%s block_til_ready() returned %d\n",
                                 __FILE__,__LINE__, info->device_name, retval);
                goto cleanup;
        }

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s open() success\n",
                         __FILE__,__LINE__, info->device_name);
        retval = 0;

cleanup:
        if (retval) {
                if (tty->count == 1)
                        info->port.tty = NULL; /* tty layer will release tty struct */
                if(info->port.count)
                        info->port.count--;
        }

        return retval;
}

/* Called when port is closed. Wait for remaining data to be
 * sent. Disable port and free resources.
 */
static void close(struct tty_struct *tty, struct file *filp)
{
        SLMP_INFO * info = tty->driver_data;

        if (sanity_check(info, tty->name, "close"))
                return;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s close() entry, count=%d\n",
                         __FILE__,__LINE__, info->device_name, info->port.count);

        if (tty_port_close_start(&info->port, tty, filp) == 0)
                goto cleanup;

        mutex_lock(&info->port.mutex);
        if (info->port.flags & ASYNC_INITIALIZED)
                wait_until_sent(tty, info->timeout);

        flush_buffer(tty);
        tty_ldisc_flush(tty);
        shutdown(info);
        mutex_unlock(&info->port.mutex);

        tty_port_close_end(&info->port, tty);
        info->port.tty = NULL;
cleanup:
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s close() exit, count=%d\n", __FILE__,__LINE__,
                        tty->driver->name, info->port.count);
}

/* Called by tty_hangup() when a hangup is signaled.
 * This is the same as closing all open descriptors for the port.
 */
static void hangup(struct tty_struct *tty)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s hangup()\n",
                         __FILE__,__LINE__, info->device_name );

        if (sanity_check(info, tty->name, "hangup"))
                return;

        mutex_lock(&info->port.mutex);
        flush_buffer(tty);
        shutdown(info);

        spin_lock_irqsave(&info->port.lock, flags);
        info->port.count = 0;
        info->port.flags &= ~ASYNC_NORMAL_ACTIVE;
        info->port.tty = NULL;
        spin_unlock_irqrestore(&info->port.lock, flags);
        mutex_unlock(&info->port.mutex);

        wake_up_interruptible(&info->port.open_wait);
}

/* Set new termios settings
 */
static void set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s set_termios()\n", __FILE__,__LINE__,
                        tty->driver->name );

        change_params(info);

        /* Handle transition to B0 status */
        if ((old_termios->c_cflag & CBAUD) && !C_BAUD(tty)) {
                info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
                spin_lock_irqsave(&info->lock,flags);
                set_signals(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }

        /* Handle transition away from B0 status */
        if (!(old_termios->c_cflag & CBAUD) && C_BAUD(tty)) {
                info->serial_signals |= SerialSignal_DTR;
                if (!C_CRTSCTS(tty) || !test_bit(TTY_THROTTLED, &tty->flags))
                        info->serial_signals |= SerialSignal_RTS;
                spin_lock_irqsave(&info->lock,flags);
                set_signals(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }

        /* Handle turning off CRTSCTS */
        if (old_termios->c_cflag & CRTSCTS && !C_CRTSCTS(tty)) {
                tty->hw_stopped = 0;
                tx_release(tty);
        }
}

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

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s write() count=%d\n",
                       __FILE__,__LINE__,info->device_name,count);

        if (sanity_check(info, tty->name, "write"))
                goto cleanup;

        if (!info->tx_buf)
                goto cleanup;

        if (info->params.mode == MGSL_MODE_HDLC) {
                if (count > info->max_frame_size) {
                        ret = -EIO;
                        goto cleanup;
                }
                if (info->tx_active)
                        goto cleanup;
                if (info->tx_count) {
                        /* send accumulated data from send_char() calls */
                        /* as frame and wait before accepting more data. */
                        tx_load_dma_buffer(info, info->tx_buf, info->tx_count);
                        goto start;
                }
                ret = info->tx_count = count;
                tx_load_dma_buffer(info, buf, count);
                goto start;
        }

        for (;;) {
                c = min_t(int, count,
                        min(info->max_frame_size - info->tx_count - 1,
                            info->max_frame_size - 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 += c;
                if (info->tx_put >= info->max_frame_size)
                        info->tx_put -= info->max_frame_size;
                info->tx_count += c;
                spin_unlock_irqrestore(&info->lock,flags);

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

        if (info->params.mode == MGSL_MODE_HDLC) {
                if (count) {
                        ret = info->tx_count = 0;
                        goto cleanup;
                }
                tx_load_dma_buffer(info, info->tx_buf, info->tx_count);
        }
start:
        if (info->tx_count && !tty->stopped && !tty->hw_stopped) {
                spin_lock_irqsave(&info->lock,flags);
                if (!info->tx_active)
                        tx_start(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }

cleanup:
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk( "%s(%d):%s write() returning=%d\n",
                        __FILE__,__LINE__,info->device_name,ret);
        return ret;
}

/* Add a character to the transmit buffer.
 */
static int put_char(struct tty_struct *tty, unsigned char ch)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;
        int ret = 0;

        if ( debug_level >= DEBUG_LEVEL_INFO ) {
                printk( "%s(%d):%s put_char(%d)\n",
                        __FILE__,__LINE__,info->device_name,ch);
        }

        if (sanity_check(info, tty->name, "put_char"))
                return 0;

        if (!info->tx_buf)
                return 0;

        spin_lock_irqsave(&info->lock,flags);

        if ( (info->params.mode != MGSL_MODE_HDLC) ||
             !info->tx_active ) {

                if (info->tx_count < info->max_frame_size - 1) {
                        info->tx_buf[info->tx_put++] = ch;
                        if (info->tx_put >= info->max_frame_size)
                                info->tx_put -= info->max_frame_size;
                        info->tx_count++;
                        ret = 1;
                }
        }

        spin_unlock_irqrestore(&info->lock,flags);
        return ret;
}

/* Send a high-priority XON/XOFF character
 */
static void send_xchar(struct tty_struct *tty, char ch)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s send_xchar(%d)\n",
                         __FILE__,__LINE__, info->device_name, ch );

        if (sanity_check(info, tty->name, "send_xchar"))
                return;

        info->x_char = ch;
        if (ch) {
                /* Make sure transmit interrupts are on */
                spin_lock_irqsave(&info->lock,flags);
                if (!info->tx_enabled)
                        tx_start(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }
}

/* Wait until the transmitter is empty.
 */
static void wait_until_sent(struct tty_struct *tty, int timeout)
{
        SLMP_INFO * info = tty->driver_data;
        unsigned long orig_jiffies, char_time;

        if (!info )
                return;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s wait_until_sent() entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (sanity_check(info, tty->name, "wait_until_sent"))
                return;

        if (!test_bit(ASYNCB_INITIALIZED, &info->port.flags))
                goto exit;

        orig_jiffies = jiffies;

        /* Set check interval to 1/5 of estimated time to
         * send a character, and make it at least 1. The check
         * interval should also be less than the timeout.
         * Note: use tight timings here to satisfy the NIST-PCTS.
         */

        if ( info->params.data_rate ) {
                char_time = info->timeout/(32 * 5);
                if (!char_time)
                        char_time++;
        } else
                char_time = 1;

        if (timeout)
                char_time = min_t(unsigned long, char_time, timeout);

        if ( info->params.mode == MGSL_MODE_HDLC ) {
                while (info->tx_active) {
                        msleep_interruptible(jiffies_to_msecs(char_time));
                        if (signal_pending(current))
                                break;
                        if (timeout && time_after(jiffies, orig_jiffies + timeout))
                                break;
                }
        } else {
                /*
                 * TODO: determine if there is something similar to USC16C32
                 *       TXSTATUS_ALL_SENT status
                 */
                while ( info->tx_active && info->tx_enabled) {
                        msleep_interruptible(jiffies_to_msecs(char_time));
                        if (signal_pending(current))
                                break;
                        if (timeout && time_after(jiffies, orig_jiffies + timeout))
                                break;
                }
        }

exit:
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s wait_until_sent() exit\n",
                         __FILE__,__LINE__, info->device_name );
}

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

        if (sanity_check(info, tty->name, "write_room"))
                return 0;

        if (info->params.mode == MGSL_MODE_HDLC) {
                ret = (info->tx_active) ? 0 : HDLC_MAX_FRAME_SIZE;
        } else {
                ret = info->max_frame_size - info->tx_count - 1;
                if (ret < 0)
                        ret = 0;
        }

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s write_room()=%d\n",
                       __FILE__, __LINE__, info->device_name, ret);

        return ret;
}

/* enable transmitter and send remaining buffered characters
 */
static void flush_chars(struct tty_struct *tty)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):%s flush_chars() entry tx_count=%d\n",
                        __FILE__,__LINE__,info->device_name,info->tx_count);

        if (sanity_check(info, tty->name, "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):%s flush_chars() entry, starting transmitter\n",
                        __FILE__,__LINE__,info->device_name );

        spin_lock_irqsave(&info->lock,flags);

        if (!info->tx_active) {
                if ( (info->params.mode == MGSL_MODE_HDLC) &&
                        info->tx_count ) {
                        /* operating in synchronous (frame oriented) mode */
                        /* copy data from circular tx_buf to */
                        /* transmit DMA buffer. */
                        tx_load_dma_buffer(info,
                                 info->tx_buf,info->tx_count);
                }
                tx_start(info);
        }

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

/* Discard all data in the send buffer
 */
static void flush_buffer(struct tty_struct *tty)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s flush_buffer() entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (sanity_check(info, tty->name, "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);

        tty_wakeup(tty);
}

/* throttle (stop) transmitter
 */
static void tx_hold(struct tty_struct *tty)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (sanity_check(info, tty->name, "tx_hold"))
                return;

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("%s(%d):%s tx_hold()\n",
                        __FILE__,__LINE__,info->device_name);

        spin_lock_irqsave(&info->lock,flags);
        if (info->tx_enabled)
                tx_stop(info);
        spin_unlock_irqrestore(&info->lock,flags);
}

/* release (start) transmitter
 */
static void tx_release(struct tty_struct *tty)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (sanity_check(info, tty->name, "tx_release"))
                return;

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("%s(%d):%s tx_release()\n",
                        __FILE__,__LINE__,info->device_name);

        spin_lock_irqsave(&info->lock,flags);
        if (!info->tx_enabled)
                tx_start(info);
        spin_unlock_irqrestore(&info->lock,flags);
}

/* Service an IOCTL request
 *
 * Arguments:
 *
 *      tty     pointer to tty instance data
 *      cmd     IOCTL command code
 *      arg     command argument/context
 *
 * Return Value:        0 if success, otherwise error code
 */
static int ioctl(struct tty_struct *tty,
                 unsigned int cmd, unsigned long arg)
{
        SLMP_INFO *info = tty->driver_data;
        void __user *argp = (void __user *)arg;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s ioctl() cmd=%08X\n", __FILE__,__LINE__,
                        info->device_name, cmd );

        if (sanity_check(info, tty->name, "ioctl"))
                return -ENODEV;

        if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
            (cmd != TIOCMIWAIT)) {
                if (tty->flags & (1 << TTY_IO_ERROR))
                    return -EIO;
        }

        switch (cmd) {
        case MGSL_IOCGPARAMS:
                return get_params(info, argp);
        case MGSL_IOCSPARAMS:
                return set_params(info, argp);
        case MGSL_IOCGTXIDLE:
                return get_txidle(info, argp);
        case MGSL_IOCSTXIDLE:
                return set_txidle(info, (int)arg);
        case MGSL_IOCTXENABLE:
                return tx_enable(info, (int)arg);
        case MGSL_IOCRXENABLE:
                return rx_enable(info, (int)arg);
        case MGSL_IOCTXABORT:
                return tx_abort(info);
        case MGSL_IOCGSTATS:
                return get_stats(info, argp);
        case MGSL_IOCWAITEVENT:
                return wait_mgsl_event(info, argp);
        case MGSL_IOCLOOPTXDONE:
                return 0; // TODO: Not supported, need to document
                /* Wait for modem input (DCD,RI,DSR,CTS) change
                 * as specified by mask in arg (TIOCM_RNG/DSR/CD/CTS)
                 */
        case TIOCMIWAIT:
                return modem_input_wait(info,(int)arg);
                
                /*
                 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
                 * Return: write counters to the user passed counter struct
                 * NB: both 1->0 and 0->1 transitions are counted except for
                 *     RI where only 0->1 is counted.
                 */
        default:
                return -ENOIOCTLCMD;
        }
        return 0;
}

static int get_icount(struct tty_struct *tty,
                                struct serial_icounter_struct *icount)
{
        SLMP_INFO *info = tty->driver_data;
        struct mgsl_icount cnow;        /* kernel counter temps */
        unsigned long flags;

        spin_lock_irqsave(&info->lock,flags);
        cnow = info->icount;
        spin_unlock_irqrestore(&info->lock,flags);

        icount->cts = cnow.cts;
        icount->dsr = cnow.dsr;
        icount->rng = cnow.rng;
        icount->dcd = cnow.dcd;
        icount->rx = cnow.rx;
        icount->tx = cnow.tx;
        icount->frame = cnow.frame;
        icount->overrun = cnow.overrun;
        icount->parity = cnow.parity;
        icount->brk = cnow.brk;
        icount->buf_overrun = cnow.buf_overrun;

        return 0;
}

/*
 * /proc fs routines....
 */

static inline void line_info(struct seq_file *m, SLMP_INFO *info)
{
        char    stat_buf[30];
        unsigned long flags;

        seq_printf(m, "%s: SCABase=%08x Mem=%08X StatusControl=%08x LCR=%08X\n"
                       "\tIRQ=%d MaxFrameSize=%u\n",
                info->device_name,
                info->phys_sca_base,
                info->phys_memory_base,
                info->phys_statctrl_base,
                info->phys_lcr_base,
                info->irq_level,
                info->max_frame_size );

        /* output current serial signal states */
        spin_lock_irqsave(&info->lock,flags);
        get_signals(info);
        spin_unlock_irqrestore(&info->lock,flags);

        stat_buf[0] = 0;
        stat_buf[1] = 0;
        if (info->serial_signals & SerialSignal_RTS)
                strcat(stat_buf, "|RTS");
        if (info->serial_signals & SerialSignal_CTS)
                strcat(stat_buf, "|CTS");
        if (info->serial_signals & SerialSignal_DTR)
                strcat(stat_buf, "|DTR");
        if (info->serial_signals & SerialSignal_DSR)
                strcat(stat_buf, "|DSR");
        if (info->serial_signals & SerialSignal_DCD)
                strcat(stat_buf, "|CD");
        if (info->serial_signals & SerialSignal_RI)
                strcat(stat_buf, "|RI");

        if (info->params.mode == MGSL_MODE_HDLC) {
                seq_printf(m, "\tHDLC txok:%d rxok:%d",
                              info->icount.txok, info->icount.rxok);
                if (info->icount.txunder)
                        seq_printf(m, " txunder:%d", info->icount.txunder);
                if (info->icount.txabort)
                        seq_printf(m, " txabort:%d", info->icount.txabort);
                if (info->icount.rxshort)
                        seq_printf(m, " rxshort:%d", info->icount.rxshort);
                if (info->icount.rxlong)
                        seq_printf(m, " rxlong:%d", info->icount.rxlong);
                if (info->icount.rxover)
                        seq_printf(m, " rxover:%d", info->icount.rxover);
                if (info->icount.rxcrc)
                        seq_printf(m, " rxlong:%d", info->icount.rxcrc);
        } else {
                seq_printf(m, "\tASYNC tx:%d rx:%d",
                              info->icount.tx, info->icount.rx);
                if (info->icount.frame)
                        seq_printf(m, " fe:%d", info->icount.frame);
                if (info->icount.parity)
                        seq_printf(m, " pe:%d", info->icount.parity);
                if (info->icount.brk)
                        seq_printf(m, " brk:%d", info->icount.brk);
                if (info->icount.overrun)
                        seq_printf(m, " oe:%d", info->icount.overrun);
        }

        /* Append serial signal status to end */
        seq_printf(m, " %s\n", stat_buf+1);

        seq_printf(m, "\ttxactive=%d bh_req=%d bh_run=%d pending_bh=%x\n",
         info->tx_active,info->bh_requested,info->bh_running,
         info->pending_bh);
}

/* Called to print information about devices
 */
static int synclinkmp_proc_show(struct seq_file *m, void *v)
{
        SLMP_INFO *info;

        seq_printf(m, "synclinkmp driver:%s\n", driver_version);

        info = synclinkmp_device_list;
        while( info ) {
                line_info(m, info);
                info = info->next_device;
        }
        return 0;
}

static int synclinkmp_proc_open(struct inode *inode, struct file *file)
{
        return single_open(file, synclinkmp_proc_show, NULL);
}

static const struct file_operations synclinkmp_proc_fops = {
        .owner          = THIS_MODULE,
        .open           = synclinkmp_proc_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

/* Return the count of bytes in transmit buffer
 */
static int chars_in_buffer(struct tty_struct *tty)
{
        SLMP_INFO *info = tty->driver_data;

        if (sanity_check(info, tty->name, "chars_in_buffer"))
                return 0;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s chars_in_buffer()=%d\n",
                       __FILE__, __LINE__, info->device_name, info->tx_count);

        return info->tx_count;
}

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

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s throttle() entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (sanity_check(info, tty->name, "throttle"))
                return;

        if (I_IXOFF(tty))
                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 unthrottle(struct tty_struct * tty)
{
        SLMP_INFO *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s unthrottle() entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (sanity_check(info, tty->name, "unthrottle"))
                return;

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

/* set or clear transmit break condition
 * break_state  -1=set break condition, 0=clear
 */
static int set_break(struct tty_struct *tty, int break_state)
{
        unsigned char RegValue;
        SLMP_INFO * info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s set_break(%d)\n",
                         __FILE__,__LINE__, info->device_name, break_state);

        if (sanity_check(info, tty->name, "set_break"))
                return -EINVAL;

        spin_lock_irqsave(&info->lock,flags);
        RegValue = read_reg(info, CTL);
        if (break_state == -1)
                RegValue |= BIT3;
        else
                RegValue &= ~BIT3;
        write_reg(info, CTL, RegValue);
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

#if SYNCLINK_GENERIC_HDLC

/**
 * called by generic HDLC layer when protocol selected (PPP, frame relay, etc.)
 * set encoding and frame check sequence (FCS) options
 *
 * dev       pointer to network device structure
 * encoding  serial encoding setting
 * parity    FCS setting
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_attach(struct net_device *dev, unsigned short encoding,
                          unsigned short parity)
{
        SLMP_INFO *info = dev_to_port(dev);
        unsigned char  new_encoding;
        unsigned short new_crctype;

        /* return error if TTY interface open */
        if (info->port.count)
                return -EBUSY;

        switch (encoding)
        {
        case ENCODING_NRZ:        new_encoding = HDLC_ENCODING_NRZ; break;
        case ENCODING_NRZI:       new_encoding = HDLC_ENCODING_NRZI_SPACE; break;
        case ENCODING_FM_MARK:    new_encoding = HDLC_ENCODING_BIPHASE_MARK; break;
        case ENCODING_FM_SPACE:   new_encoding = HDLC_ENCODING_BIPHASE_SPACE; break;
        case ENCODING_MANCHESTER: new_encoding = HDLC_ENCODING_BIPHASE_LEVEL; break;
        default: return -EINVAL;
        }

        switch (parity)
        {
        case PARITY_NONE:            new_crctype = HDLC_CRC_NONE; break;
        case PARITY_CRC16_PR1_CCITT: new_crctype = HDLC_CRC_16_CCITT; break;
        case PARITY_CRC32_PR1_CCITT: new_crctype = HDLC_CRC_32_CCITT; break;
        default: return -EINVAL;
        }

        info->params.encoding = new_encoding;
        info->params.crc_type = new_crctype;

        /* if network interface up, reprogram hardware */
        if (info->netcount)
                program_hw(info);

        return 0;
}

/**
 * called by generic HDLC layer to send frame
 *
 * skb  socket buffer containing HDLC frame
 * dev  pointer to network device structure
 */
static netdev_tx_t hdlcdev_xmit(struct sk_buff *skb,
                                      struct net_device *dev)
{
        SLMP_INFO *info = dev_to_port(dev);
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk(KERN_INFO "%s:hdlc_xmit(%s)\n",__FILE__,dev->name);

        /* stop sending until this frame completes */
        netif_stop_queue(dev);

        /* copy data to device buffers */
        info->tx_count = skb->len;
        tx_load_dma_buffer(info, skb->data, skb->len);

        /* update network statistics */
        dev->stats.tx_packets++;
        dev->stats.tx_bytes += skb->len;

        /* done with socket buffer, so free it */
        dev_kfree_skb(skb);

        /* save start time for transmit timeout detection */
        dev->trans_start = jiffies;

        /* start hardware transmitter if necessary */
        spin_lock_irqsave(&info->lock,flags);
        if (!info->tx_active)
                tx_start(info);
        spin_unlock_irqrestore(&info->lock,flags);

        return NETDEV_TX_OK;
}

/**
 * called by network layer when interface enabled
 * claim resources and initialize hardware
 *
 * dev  pointer to network device structure
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_open(struct net_device *dev)
{
        SLMP_INFO *info = dev_to_port(dev);
        int rc;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s:hdlcdev_open(%s)\n",__FILE__,dev->name);

        /* generic HDLC layer open processing */
        rc = hdlc_open(dev);
        if (rc)
                return rc;

        /* arbitrate between network and tty opens */
        spin_lock_irqsave(&info->netlock, flags);
        if (info->port.count != 0 || info->netcount != 0) {
                printk(KERN_WARNING "%s: hdlc_open returning busy\n", dev->name);
                spin_unlock_irqrestore(&info->netlock, flags);
                return -EBUSY;
        }
        info->netcount=1;
        spin_unlock_irqrestore(&info->netlock, flags);

        /* claim resources and init adapter */
        if ((rc = startup(info)) != 0) {
                spin_lock_irqsave(&info->netlock, flags);
                info->netcount=0;
                spin_unlock_irqrestore(&info->netlock, flags);
                return rc;
        }

        /* assert RTS and DTR, apply hardware settings */
        info->serial_signals |= SerialSignal_RTS | SerialSignal_DTR;
        program_hw(info);

        /* enable network layer transmit */
        dev->trans_start = jiffies;
        netif_start_queue(dev);

        /* inform generic HDLC layer of current DCD status */
        spin_lock_irqsave(&info->lock, flags);
        get_signals(info);
        spin_unlock_irqrestore(&info->lock, flags);
        if (info->serial_signals & SerialSignal_DCD)
                netif_carrier_on(dev);
        else
                netif_carrier_off(dev);
        return 0;
}

/**
 * called by network layer when interface is disabled
 * shutdown hardware and release resources
 *
 * dev  pointer to network device structure
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_close(struct net_device *dev)
{
        SLMP_INFO *info = dev_to_port(dev);
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s:hdlcdev_close(%s)\n",__FILE__,dev->name);

        netif_stop_queue(dev);

        /* shutdown adapter and release resources */
        shutdown(info);

        hdlc_close(dev);

        spin_lock_irqsave(&info->netlock, flags);
        info->netcount=0;
        spin_unlock_irqrestore(&info->netlock, flags);

        return 0;
}

/**
 * called by network layer to process IOCTL call to network device
 *
 * dev  pointer to network device structure
 * ifr  pointer to network interface request structure
 * cmd  IOCTL command code
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        const size_t size = sizeof(sync_serial_settings);
        sync_serial_settings new_line;
        sync_serial_settings __user *line = ifr->ifr_settings.ifs_ifsu.sync;
        SLMP_INFO *info = dev_to_port(dev);
        unsigned int flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s:hdlcdev_ioctl(%s)\n",__FILE__,dev->name);

        /* return error if TTY interface open */
        if (info->port.count)
                return -EBUSY;

        if (cmd != SIOCWANDEV)
                return hdlc_ioctl(dev, ifr, cmd);

        switch(ifr->ifr_settings.type) {
        case IF_GET_IFACE: /* return current sync_serial_settings */

                ifr->ifr_settings.type = IF_IFACE_SYNC_SERIAL;
                if (ifr->ifr_settings.size < size) {
                        ifr->ifr_settings.size = size; /* data size wanted */
                        return -ENOBUFS;
                }

                flags = info->params.flags & (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
                                              HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
                                              HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
                                              HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);

                memset(&new_line, 0, sizeof(new_line));
                switch (flags){
                case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN): new_line.clock_type = CLOCK_EXT; break;
                case (HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_INT; break;
                case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_TXINT; break;
                case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN): new_line.clock_type = CLOCK_TXFROMRX; break;
                default: new_line.clock_type = CLOCK_DEFAULT;
                }

                new_line.clock_rate = info->params.clock_speed;
                new_line.loopback   = info->params.loopback ? 1:0;

                if (copy_to_user(line, &new_line, size))
                        return -EFAULT;
                return 0;

        case IF_IFACE_SYNC_SERIAL: /* set sync_serial_settings */

                if(!capable(CAP_NET_ADMIN))
                        return -EPERM;
                if (copy_from_user(&new_line, line, size))
                        return -EFAULT;

                switch (new_line.clock_type)
                {
                case CLOCK_EXT:      flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN; break;
                case CLOCK_TXFROMRX: flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN; break;
                case CLOCK_INT:      flags = HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG;    break;
                case CLOCK_TXINT:    flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG;    break;
                case CLOCK_DEFAULT:  flags = info->params.flags &
                                             (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
                                              HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
                                              HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
                                              HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN); break;
                default: return -EINVAL;
                }

                if (new_line.loopback != 0 && new_line.loopback != 1)
                        return -EINVAL;

                info->params.flags &= ~(HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
                                        HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
                                        HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
                                        HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
                info->params.flags |= flags;

                info->params.loopback = new_line.loopback;

                if (flags & (HDLC_FLAG_RXC_BRG | HDLC_FLAG_TXC_BRG))
                        info->params.clock_speed = new_line.clock_rate;
                else
                        info->params.clock_speed = 0;

                /* if network interface up, reprogram hardware */
                if (info->netcount)
                        program_hw(info);
                return 0;

        default:
                return hdlc_ioctl(dev, ifr, cmd);
        }
}

/**
 * called by network layer when transmit timeout is detected
 *
 * dev  pointer to network device structure
 */
static void hdlcdev_tx_timeout(struct net_device *dev)
{
        SLMP_INFO *info = dev_to_port(dev);
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("hdlcdev_tx_timeout(%s)\n",dev->name);

        dev->stats.tx_errors++;
        dev->stats.tx_aborted_errors++;

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

        netif_wake_queue(dev);
}

/**
 * called by device driver when transmit completes
 * reenable network layer transmit if stopped
 *
 * info  pointer to device instance information
 */
static void hdlcdev_tx_done(SLMP_INFO *info)
{
        if (netif_queue_stopped(info->netdev))
                netif_wake_queue(info->netdev);
}

/**
 * called by device driver when frame received
 * pass frame to network layer
 *
 * info  pointer to device instance information
 * buf   pointer to buffer contianing frame data
 * size  count of data bytes in buf
 */
static void hdlcdev_rx(SLMP_INFO *info, char *buf, int size)
{
        struct sk_buff *skb = dev_alloc_skb(size);
        struct net_device *dev = info->netdev;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("hdlcdev_rx(%s)\n",dev->name);

        if (skb == NULL) {
                printk(KERN_NOTICE "%s: can't alloc skb, dropping packet\n",
                       dev->name);
                dev->stats.rx_dropped++;
                return;
        }

        memcpy(skb_put(skb, size), buf, size);

        skb->protocol = hdlc_type_trans(skb, dev);

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += size;

        netif_rx(skb);
}

static const struct net_device_ops hdlcdev_ops = {
        .ndo_open       = hdlcdev_open,
        .ndo_stop       = hdlcdev_close,
        .ndo_change_mtu = hdlc_change_mtu,
        .ndo_start_xmit = hdlc_start_xmit,
        .ndo_do_ioctl   = hdlcdev_ioctl,
        .ndo_tx_timeout = hdlcdev_tx_timeout,
};

/**
 * called by device driver when adding device instance
 * do generic HDLC initialization
 *
 * info  pointer to device instance information
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_init(SLMP_INFO *info)
{
        int rc;
        struct net_device *dev;
        hdlc_device *hdlc;

        /* allocate and initialize network and HDLC layer objects */

        dev = alloc_hdlcdev(info);
        if (!dev) {
                printk(KERN_ERR "%s:hdlc device allocation failure\n",__FILE__);
                return -ENOMEM;
        }

        /* for network layer reporting purposes only */
        dev->mem_start = info->phys_sca_base;
        dev->mem_end   = info->phys_sca_base + SCA_BASE_SIZE - 1;
        dev->irq       = info->irq_level;

        /* network layer callbacks and settings */
        dev->netdev_ops     = &hdlcdev_ops;
        dev->watchdog_timeo = 10 * HZ;
        dev->tx_queue_len   = 50;

        /* generic HDLC layer callbacks and settings */
        hdlc         = dev_to_hdlc(dev);
        hdlc->attach = hdlcdev_attach;
        hdlc->xmit   = hdlcdev_xmit;

        /* register objects with HDLC layer */
        rc = register_hdlc_device(dev);
        if (rc) {
                printk(KERN_WARNING "%s:unable to register hdlc device\n",__FILE__);
                free_netdev(dev);
                return rc;
        }

        info->netdev = dev;
        return 0;
}

/**
 * called by device driver when removing device instance
 * do generic HDLC cleanup
 *
 * info  pointer to device instance information
 */
static void hdlcdev_exit(SLMP_INFO *info)
{
        unregister_hdlc_device(info->netdev);
        free_netdev(info->netdev);
        info->netdev = NULL;
}

#endif /* CONFIG_HDLC */


/* Return next bottom half action to perform.
 * Return Value:        BH action code or 0 if nothing to do.
 */
static int bh_action(SLMP_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;
}

/* Perform bottom half processing of work items queued by ISR.
 */
static void bh_handler(struct work_struct *work)
{
        SLMP_INFO *info = container_of(work, SLMP_INFO, task);
        int action;

        if ( debug_level >= DEBUG_LEVEL_BH )

                printk( "%s(%d):%s bh_handler() entry\n",
                        __FILE__,__LINE__,info->device_name);

        info->bh_running = true;

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

                /* Process work item */
                if ( debug_level >= DEBUG_LEVEL_BH )
                        printk( "%s(%d):%s bh_handler() work item action=%d\n",
                                __FILE__,__LINE__,info->device_name, action);

                switch (action) {

                case BH_RECEIVE:
                        bh_receive(info);
                        break;
                case BH_TRANSMIT:
                        bh_transmit(info);
                        break;
                case BH_STATUS:
                        bh_status(info);
                        break;
                default:
                        /* unknown work item ID */
                        printk("%s(%d):%s Unknown work item ID=%08X!\n",
                                __FILE__,__LINE__,info->device_name,action);
                        break;
                }
        }

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):%s bh_handler() exit\n",
                        __FILE__,__LINE__,info->device_name);
}

static void bh_receive(SLMP_INFO *info)
{
        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):%s bh_receive()\n",
                        __FILE__,__LINE__,info->device_name);

        while( rx_get_frame(info) );
}

static void bh_transmit(SLMP_INFO *info)
{
        struct tty_struct *tty = info->port.tty;

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):%s bh_transmit() entry\n",
                        __FILE__,__LINE__,info->device_name);

        if (tty)
                tty_wakeup(tty);
}

static void bh_status(SLMP_INFO *info)
{
        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):%s bh_status() entry\n",
                        __FILE__,__LINE__,info->device_name);

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

static void isr_timer(SLMP_INFO * info)
{
        unsigned char timer = (info->port_num & 1) ? TIMER2 : TIMER0;

        /* IER2<7..4> = timer<3..0> interrupt enables (0=disabled) */
        write_reg(info, IER2, 0);

        /* TMCS, Timer Control/Status Register
         *
         * 07      CMF, Compare match flag (read only) 1=match
         * 06      ECMI, CMF Interrupt Enable: 0=disabled
         * 05      Reserved, must be 0
         * 04      TME, Timer Enable
         * 03..00  Reserved, must be 0
         *
         * 0000 0000
         */
        write_reg(info, (unsigned char)(timer + TMCS), 0);

        info->irq_occurred = true;

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_timer()\n",
                        __FILE__,__LINE__,info->device_name);
}

static void isr_rxint(SLMP_INFO * info)
{
        struct tty_struct *tty = info->port.tty;
        struct  mgsl_icount *icount = &info->icount;
        unsigned char status = read_reg(info, SR1) & info->ie1_value & (FLGD + IDLD + CDCD + BRKD);
        unsigned char status2 = read_reg(info, SR2) & info->ie2_value & OVRN;

        /* clear status bits */
        if (status)
                write_reg(info, SR1, status);

        if (status2)
                write_reg(info, SR2, status2);
        
        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_rxint status=%02X %02x\n",
                        __FILE__,__LINE__,info->device_name,status,status2);

        if (info->params.mode == MGSL_MODE_ASYNC) {
                if (status & BRKD) {
                        icount->brk++;

                        /* process break detection if tty control
                         * is not set to ignore it
                         */
                        if (!(status & info->ignore_status_mask1)) {
                                if (info->read_status_mask1 & BRKD) {
                                        tty_insert_flip_char(&info->port, 0, TTY_BREAK);
                                        if (tty && (info->port.flags & ASYNC_SAK))
                                                do_SAK(tty);
                                }
                        }
                }
        }
        else {
                if (status & (FLGD|IDLD)) {
                        if (status & FLGD)
                                info->icount.exithunt++;
                        else if (status & IDLD)
                                info->icount.rxidle++;
                        wake_up_interruptible(&info->event_wait_q);
                }
        }

        if (status & CDCD) {
                /* simulate a common modem status change interrupt
                 * for our handler
                 */
                get_signals( info );
                isr_io_pin(info,
                        MISCSTATUS_DCD_LATCHED|(info->serial_signals&SerialSignal_DCD));
        }
}

/*
 * handle async rx data interrupts
 */
static void isr_rxrdy(SLMP_INFO * info)
{
        u16 status;
        unsigned char DataByte;
        struct  mgsl_icount *icount = &info->icount;

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_rxrdy\n",
                        __FILE__,__LINE__,info->device_name);

        while((status = read_reg(info,CST0)) & BIT0)
        {
                int flag = 0;
                bool over = false;
                DataByte = read_reg(info,TRB);

                icount->rx++;

                if ( status & (PE + FRME + OVRN) ) {
                        printk("%s(%d):%s rxerr=%04X\n",
                                __FILE__,__LINE__,info->device_name,status);

                        /* update error statistics */
                        if (status & PE)
                                icount->parity++;
                        else if (status & FRME)
                                icount->frame++;
                        else if (status & OVRN)
                                icount->overrun++;

                        /* discard char if tty control flags say so */
                        if (status & info->ignore_status_mask2)
                                continue;

                        status &= info->read_status_mask2;

                        if (status & PE)
                                flag = TTY_PARITY;
                        else if (status & FRME)
                                flag = TTY_FRAME;
                        if (status & OVRN) {
                                /* Overrun is special, since it's
                                 * reported immediately, and doesn't
                                 * affect the current character
                                 */
                                over = true;
                        }
                }       /* end of if (error) */

                tty_insert_flip_char(&info->port, DataByte, flag);
                if (over)
                        tty_insert_flip_char(&info->port, 0, TTY_OVERRUN);
        }

        if ( debug_level >= DEBUG_LEVEL_ISR ) {
                printk("%s(%d):%s rx=%d brk=%d parity=%d frame=%d overrun=%d\n",
                        __FILE__,__LINE__,info->device_name,
                        icount->rx,icount->brk,icount->parity,
                        icount->frame,icount->overrun);
        }

        tty_flip_buffer_push(&info->port);
}

static void isr_txeom(SLMP_INFO * info, unsigned char status)
{
        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_txeom status=%02x\n",
                        __FILE__,__LINE__,info->device_name,status);

        write_reg(info, TXDMA + DIR, 0x00); /* disable Tx DMA IRQs */
        write_reg(info, TXDMA + DSR, 0xc0); /* clear IRQs and disable DMA */
        write_reg(info, TXDMA + DCMD, SWABORT); /* reset/init DMA channel */

        if (status & UDRN) {
                write_reg(info, CMD, TXRESET);
                write_reg(info, CMD, TXENABLE);
        } else
                write_reg(info, CMD, TXBUFCLR);

        /* disable and clear tx interrupts */
        info->ie0_value &= ~TXRDYE;
        info->ie1_value &= ~(IDLE + UDRN);
        write_reg16(info, IE0, (unsigned short)((info->ie1_value << 8) + info->ie0_value));
        write_reg(info, SR1, (unsigned char)(UDRN + IDLE));

        if ( info->tx_active ) {
                if (info->params.mode != MGSL_MODE_ASYNC) {
                        if (status & UDRN)
                                info->icount.txunder++;
                        else if (status & IDLE)
                                info->icount.txok++;
                }

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

                del_timer(&info->tx_timer);

                if (info->params.mode != MGSL_MODE_ASYNC && info->drop_rts_on_tx_done ) {
                        info->serial_signals &= ~SerialSignal_RTS;
                        info->drop_rts_on_tx_done = false;
                        set_signals(info);
                }

#if SYNCLINK_GENERIC_HDLC
                if (info->netcount)
                        hdlcdev_tx_done(info);
                else
#endif
                {
                        if (info->port.tty && (info->port.tty->stopped || info->port.tty->hw_stopped)) {
                                tx_stop(info);
                                return;
                        }
                        info->pending_bh |= BH_TRANSMIT;
                }
        }
}


/*
 * handle tx status interrupts
 */
static void isr_txint(SLMP_INFO * info)
{
        unsigned char status = read_reg(info, SR1) & info->ie1_value & (UDRN + IDLE + CCTS);

        /* clear status bits */
        write_reg(info, SR1, status);

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_txint status=%02x\n",
                        __FILE__,__LINE__,info->device_name,status);

        if (status & (UDRN + IDLE))
                isr_txeom(info, status);

        if (status & CCTS) {
                /* simulate a common modem status change interrupt
                 * for our handler
                 */
                get_signals( info );
                isr_io_pin(info,
                        MISCSTATUS_CTS_LATCHED|(info->serial_signals&SerialSignal_CTS));

        }
}

/*
 * handle async tx data interrupts
 */
static void isr_txrdy(SLMP_INFO * info)
{
        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_txrdy() tx_count=%d\n",
                        __FILE__,__LINE__,info->device_name,info->tx_count);

        if (info->params.mode != MGSL_MODE_ASYNC) {
                /* disable TXRDY IRQ, enable IDLE IRQ */
                info->ie0_value &= ~TXRDYE;
                info->ie1_value |= IDLE;
                write_reg16(info, IE0, (unsigned short)((info->ie1_value << 8) + info->ie0_value));
                return;
        }

        if (info->port.tty && (info->port.tty->stopped || info->port.tty->hw_stopped)) {
                tx_stop(info);
                return;
        }

        if ( info->tx_count )
                tx_load_fifo( info );
        else {
                info->tx_active = false;
                info->ie0_value &= ~TXRDYE;
                write_reg(info, IE0, info->ie0_value);
        }

        if (info->tx_count < WAKEUP_CHARS)
                info->pending_bh |= BH_TRANSMIT;
}

static void isr_rxdmaok(SLMP_INFO * info)
{
        /* BIT7 = EOT (end of transfer)
         * BIT6 = EOM (end of message/frame)
         */
        unsigned char status = read_reg(info,RXDMA + DSR) & 0xc0;

        /* clear IRQ (BIT0 must be 1 to prevent clearing DE bit) */
        write_reg(info, RXDMA + DSR, (unsigned char)(status | 1));

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_rxdmaok(), status=%02x\n",
                        __FILE__,__LINE__,info->device_name,status);

        info->pending_bh |= BH_RECEIVE;
}

static void isr_rxdmaerror(SLMP_INFO * info)
{
        /* BIT5 = BOF (buffer overflow)
         * BIT4 = COF (counter overflow)
         */
        unsigned char status = read_reg(info,RXDMA + DSR) & 0x30;

        /* clear IRQ (BIT0 must be 1 to prevent clearing DE bit) */
        write_reg(info, RXDMA + DSR, (unsigned char)(status | 1));

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_rxdmaerror(), status=%02x\n",
                        __FILE__,__LINE__,info->device_name,status);

        info->rx_overflow = true;
        info->pending_bh |= BH_RECEIVE;
}

static void isr_txdmaok(SLMP_INFO * info)
{
        unsigned char status_reg1 = read_reg(info, SR1);

        write_reg(info, TXDMA + DIR, 0x00);     /* disable Tx DMA IRQs */
        write_reg(info, TXDMA + DSR, 0xc0); /* clear IRQs and disable DMA */
        write_reg(info, TXDMA + DCMD, SWABORT); /* reset/init DMA channel */

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_txdmaok(), status=%02x\n",
                        __FILE__,__LINE__,info->device_name,status_reg1);

        /* program TXRDY as FIFO empty flag, enable TXRDY IRQ */
        write_reg16(info, TRC0, 0);
        info->ie0_value |= TXRDYE;
        write_reg(info, IE0, info->ie0_value);
}

static void isr_txdmaerror(SLMP_INFO * info)
{
        /* BIT5 = BOF (buffer overflow)
         * BIT4 = COF (counter overflow)
         */
        unsigned char status = read_reg(info,TXDMA + DSR) & 0x30;

        /* clear IRQ (BIT0 must be 1 to prevent clearing DE bit) */
        write_reg(info, TXDMA + DSR, (unsigned char)(status | 1));

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):%s isr_txdmaerror(), status=%02x\n",
                        __FILE__,__LINE__,info->device_name,status);
}

/* handle input serial signal changes
 */
static void isr_io_pin( SLMP_INFO *info, u16 status )
{
        struct  mgsl_icount *icount;

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):isr_io_pin status=%04X\n",
                        __FILE__,__LINE__,status);

        if (status & (MISCSTATUS_CTS_LATCHED | MISCSTATUS_DCD_LATCHED |
                      MISCSTATUS_DSR_LATCHED | MISCSTATUS_RI_LATCHED) ) {
                icount = &info->icount;
                /* update input line counters */
                if (status & MISCSTATUS_RI_LATCHED) {
                        icount->rng++;
                        if ( status & SerialSignal_RI )
                                info->input_signal_events.ri_up++;
                        else
                                info->input_signal_events.ri_down++;
                }
                if (status & MISCSTATUS_DSR_LATCHED) {
                        icount->dsr++;
                        if ( status & SerialSignal_DSR )
                                info->input_signal_events.dsr_up++;
                        else
                                info->input_signal_events.dsr_down++;
                }
                if (status & MISCSTATUS_DCD_LATCHED) {
                        if ((info->dcd_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT) {
                                info->ie1_value &= ~CDCD;
                                write_reg(info, IE1, info->ie1_value);
                        }
                        icount->dcd++;
                        if (status & SerialSignal_DCD) {
                                info->input_signal_events.dcd_up++;
                        } else
                                info->input_signal_events.dcd_down++;
#if SYNCLINK_GENERIC_HDLC
                        if (info->netcount) {
                                if (status & SerialSignal_DCD)
                                        netif_carrier_on(info->netdev);
                                else
                                        netif_carrier_off(info->netdev);
                        }
#endif
                }
                if (status & MISCSTATUS_CTS_LATCHED)
                {
                        if ((info->cts_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT) {
                                info->ie1_value &= ~CCTS;
                                write_reg(info, IE1, info->ie1_value);
                        }
                        icount->cts++;
                        if ( status & 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 ( (info->port.flags & ASYNC_CHECK_CD) &&
                     (status & MISCSTATUS_DCD_LATCHED) ) {
                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                printk("%s CD now %s...", info->device_name,
                                       (status & SerialSignal_DCD) ? "on" : "off");
                        if (status & SerialSignal_DCD)
                                wake_up_interruptible(&info->port.open_wait);
                        else {
                                if ( debug_level >= DEBUG_LEVEL_ISR )
                                        printk("doing serial hangup...");
                                if (info->port.tty)
                                        tty_hangup(info->port.tty);
                        }
                }

                if (tty_port_cts_enabled(&info->port) &&
                     (status & MISCSTATUS_CTS_LATCHED) ) {
                        if ( info->port.tty ) {
                                if (info->port.tty->hw_stopped) {
                                        if (status & SerialSignal_CTS) {
                                                if ( debug_level >= DEBUG_LEVEL_ISR )
                                                        printk("CTS tx start...");
                                                info->port.tty->hw_stopped = 0;
                                                tx_start(info);
                                                info->pending_bh |= BH_TRANSMIT;
                                                return;
                                        }
                                } else {
                                        if (!(status & SerialSignal_CTS)) {
                                                if ( debug_level >= DEBUG_LEVEL_ISR )
                                                        printk("CTS tx stop...");
                                                info->port.tty->hw_stopped = 1;
                                                tx_stop(info);
                                        }
                                }
                        }
                }
        }

        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
 *      regs            interrupted processor context
 */
static irqreturn_t synclinkmp_interrupt(int dummy, void *dev_id)
{
        SLMP_INFO *info = dev_id;
        unsigned char status, status0, status1=0;
        unsigned char dmastatus, dmastatus0, dmastatus1=0;
        unsigned char timerstatus0, timerstatus1=0;
        unsigned char shift;
        unsigned int i;
        unsigned short tmp;

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk(KERN_DEBUG "%s(%d): synclinkmp_interrupt(%d)entry.\n",
                        __FILE__, __LINE__, info->irq_level);

        spin_lock(&info->lock);

        for(;;) {

                /* get status for SCA0 (ports 0-1) */
                tmp = read_reg16(info, ISR0);   /* get ISR0 and ISR1 in one read */
                status0 = (unsigned char)tmp;
                dmastatus0 = (unsigned char)(tmp>>8);
                timerstatus0 = read_reg(info, ISR2);

                if ( debug_level >= DEBUG_LEVEL_ISR )
                        printk(KERN_DEBUG "%s(%d):%s status0=%02x, dmastatus0=%02x, timerstatus0=%02x\n",
                                __FILE__, __LINE__, info->device_name,
                                status0, dmastatus0, timerstatus0);

                if (info->port_count == 4) {
                        /* get status for SCA1 (ports 2-3) */
                        tmp = read_reg16(info->port_array[2], ISR0);
                        status1 = (unsigned char)tmp;
                        dmastatus1 = (unsigned char)(tmp>>8);
                        timerstatus1 = read_reg(info->port_array[2], ISR2);

                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                printk("%s(%d):%s status1=%02x, dmastatus1=%02x, timerstatus1=%02x\n",
                                        __FILE__,__LINE__,info->device_name,
                                        status1,dmastatus1,timerstatus1);
                }

                if (!status0 && !dmastatus0 && !timerstatus0 &&
                         !status1 && !dmastatus1 && !timerstatus1)
                        break;

                for(i=0; i < info->port_count ; i++) {
                        if (info->port_array[i] == NULL)
                                continue;
                        if (i < 2) {
                                status = status0;
                                dmastatus = dmastatus0;
                        } else {
                                status = status1;
                                dmastatus = dmastatus1;
                        }

                        shift = i & 1 ? 4 :0;

                        if (status & BIT0 << shift)
                                isr_rxrdy(info->port_array[i]);
                        if (status & BIT1 << shift)
                                isr_txrdy(info->port_array[i]);
                        if (status & BIT2 << shift)
                                isr_rxint(info->port_array[i]);
                        if (status & BIT3 << shift)
                                isr_txint(info->port_array[i]);

                        if (dmastatus & BIT0 << shift)
                                isr_rxdmaerror(info->port_array[i]);
                        if (dmastatus & BIT1 << shift)
                                isr_rxdmaok(info->port_array[i]);
                        if (dmastatus & BIT2 << shift)
                                isr_txdmaerror(info->port_array[i]);
                        if (dmastatus & BIT3 << shift)
                                isr_txdmaok(info->port_array[i]);
                }

                if (timerstatus0 & (BIT5 | BIT4))
                        isr_timer(info->port_array[0]);
                if (timerstatus0 & (BIT7 | BIT6))
                        isr_timer(info->port_array[1]);
                if (timerstatus1 & (BIT5 | BIT4))
                        isr_timer(info->port_array[2]);
                if (timerstatus1 & (BIT7 | BIT6))
                        isr_timer(info->port_array[3]);
        }

        for(i=0; i < info->port_count ; i++) {
                SLMP_INFO * port = info->port_array[i];

                /* Request bottom half processing if there's something
                 * for it to do and the bh is not already running.
                 *
                 * Note: startup adapter diags require interrupts.
                 * do not request bottom half processing if the
                 * device is not open in a normal mode.
                 */
                if ( port && (port->port.count || port->netcount) &&
                     port->pending_bh && !port->bh_running &&
                     !port->bh_requested ) {
                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                printk("%s(%d):%s queueing bh task.\n",
                                        __FILE__,__LINE__,port->device_name);
                        schedule_work(&port->task);
                        port->bh_requested = true;
                }
        }

        spin_unlock(&info->lock);

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk(KERN_DEBUG "%s(%d):synclinkmp_interrupt(%d)exit.\n",
                        __FILE__, __LINE__, info->irq_level);
        return IRQ_HANDLED;
}

/* Initialize and start device.
 */
static int startup(SLMP_INFO * info)
{
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("%s(%d):%s tx_releaseup()\n",__FILE__,__LINE__,info->device_name);

        if (info->port.flags & ASYNC_INITIALIZED)
                return 0;

        if (!info->tx_buf) {
                info->tx_buf = kmalloc(info->max_frame_size, GFP_KERNEL);
                if (!info->tx_buf) {
                        printk(KERN_ERR"%s(%d):%s can't allocate transmit buffer\n",
                                __FILE__,__LINE__,info->device_name);
                        return -ENOMEM;
                }
        }

        info->pending_bh = 0;

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

        /* program hardware for current parameters */
        reset_port(info);

        change_params(info);

        mod_timer(&info->status_timer, jiffies + msecs_to_jiffies(10));

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

        info->port.flags |= ASYNC_INITIALIZED;

        return 0;
}

/* Called by close() and hangup() to shutdown hardware
 */
static void shutdown(SLMP_INFO * info)
{
        unsigned long flags;

        if (!(info->port.flags & ASYNC_INITIALIZED))
                return;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s synclinkmp_shutdown()\n",
                         __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(&info->tx_timer);
        del_timer(&info->status_timer);

        kfree(info->tx_buf);
        info->tx_buf = NULL;

        spin_lock_irqsave(&info->lock,flags);

        reset_port(info);

        if (!info->port.tty || info->port.tty->termios.c_cflag & HUPCL) {
                info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
                set_signals(info);
        }

        spin_unlock_irqrestore(&info->lock,flags);

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

        info->port.flags &= ~ASYNC_INITIALIZED;
}

static void program_hw(SLMP_INFO *info)
{
        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;

        info->ie1_value |= (CDCD|CCTS);
        write_reg(info, IE1, info->ie1_value);

        get_signals(info);

        if (info->netcount || (info->port.tty && info->port.tty->termios.c_cflag & CREAD) )
                rx_start(info);

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

/* Reconfigure adapter based on new parameters
 */
static void change_params(SLMP_INFO *info)
{
        unsigned cflag;
        int bits_per_char;

        if (!info->port.tty)
                return;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s change_params()\n",
                         __FILE__,__LINE__, info->device_name );

        cflag = info->port.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;
              /* Never happens, but GCC is too dumb to figure it out */
              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(info->port.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 */

        if (cflag & CRTSCTS)
                info->port.flags |= ASYNC_CTS_FLOW;
        else
                info->port.flags &= ~ASYNC_CTS_FLOW;

        if (cflag & CLOCAL)
                info->port.flags &= ~ASYNC_CHECK_CD;
        else
                info->port.flags |= ASYNC_CHECK_CD;

        /* process tty input control flags */

        info->read_status_mask2 = OVRN;
        if (I_INPCK(info->port.tty))
                info->read_status_mask2 |= PE | FRME;
        if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
                info->read_status_mask1 |= BRKD;
        if (I_IGNPAR(info->port.tty))
                info->ignore_status_mask2 |= PE | FRME;
        if (I_IGNBRK(info->port.tty)) {
                info->ignore_status_mask1 |= BRKD;
                /* If ignoring parity and break indicators, ignore
                 * overruns too.  (For real raw support).
                 */
                if (I_IGNPAR(info->port.tty))
                        info->ignore_status_mask2 |= OVRN;
        }

        program_hw(info);
}

static int get_stats(SLMP_INFO * info, struct mgsl_icount __user *user_icount)
{
        int err;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s get_params()\n",
                         __FILE__,__LINE__, info->device_name);

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

        return 0;
}

static int get_params(SLMP_INFO * info, MGSL_PARAMS __user *user_params)
{
        int err;
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s get_params()\n",
                         __FILE__,__LINE__, info->device_name);

        mutex_lock(&info->port.mutex);
        COPY_TO_USER(err,user_params, &info->params, sizeof(MGSL_PARAMS));
        mutex_unlock(&info->port.mutex);
        if (err) {
                if ( debug_level >= DEBUG_LEVEL_INFO )
                        printk( "%s(%d):%s get_params() user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }

        return 0;
}

static int set_params(SLMP_INFO * info, MGSL_PARAMS __user *new_params)
{
        unsigned long flags;
        MGSL_PARAMS tmp_params;
        int err;

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

        mutex_lock(&info->port.mutex);
        spin_lock_irqsave(&info->lock,flags);
        memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
        spin_unlock_irqrestore(&info->lock,flags);

        change_params(info);
        mutex_unlock(&info->port.mutex);

        return 0;
}

static int get_txidle(SLMP_INFO * info, int __user *idle_mode)
{
        int err;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s get_txidle()=%d\n",
                         __FILE__,__LINE__, info->device_name, info->idle_mode);

        COPY_TO_USER(err,idle_mode, &info->idle_mode, sizeof(int));
        if (err) {
                if ( debug_level >= DEBUG_LEVEL_INFO )
                        printk( "%s(%d):%s get_txidle() user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }

        return 0;
}

static int set_txidle(SLMP_INFO * info, int idle_mode)
{
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s set_txidle(%d)\n",
                        __FILE__,__LINE__,info->device_name, idle_mode );

        spin_lock_irqsave(&info->lock,flags);
        info->idle_mode = idle_mode;
        tx_set_idle( info );
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

static int tx_enable(SLMP_INFO * info, int enable)
{
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s tx_enable(%d)\n",
                        __FILE__,__LINE__,info->device_name, enable);

        spin_lock_irqsave(&info->lock,flags);
        if ( enable ) {
                if ( !info->tx_enabled ) {
                        tx_start(info);
                }
        } else {
                if ( info->tx_enabled )
                        tx_stop(info);
        }
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

/* abort send HDLC frame
 */
static int tx_abort(SLMP_INFO * info)
{
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s tx_abort()\n",
                        __FILE__,__LINE__,info->device_name);

        spin_lock_irqsave(&info->lock,flags);
        if ( info->tx_active && info->params.mode == MGSL_MODE_HDLC ) {
                info->ie1_value &= ~UDRN;
                info->ie1_value |= IDLE;
                write_reg(info, IE1, info->ie1_value);  /* disable tx status interrupts */
                write_reg(info, SR1, (unsigned char)(IDLE + UDRN));     /* clear pending */

                write_reg(info, TXDMA + DSR, 0);                /* disable DMA channel */
                write_reg(info, TXDMA + DCMD, SWABORT); /* reset/init DMA channel */

                write_reg(info, CMD, TXABORT);
        }
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

static int rx_enable(SLMP_INFO * info, int enable)
{
        unsigned long flags;