// SPDX-License-Identifier: GPL-1.0+
/*
 * $Id: synclink.c,v 4.38 2005/11/07 16:30:34 paulkf Exp $
 *
 * Device driver for Microgate SyncLink ISA and PCI
 * high speed multiprotocol serial adapters.
 *
 * 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
 *
 * Original release 01/11/99
 *
 * This driver is primarily intended for use in synchronous
 * HDLC mode. Asynchronous mode is also provided.
 *
 * When operating in synchronous mode, each call to mgsl_write()
 * contains exactly one complete HDLC frame. Calling mgsl_put_char
 * will start assembling an HDLC frame that will not be sent until
 * mgsl_flush_chars or mgsl_write is called.
 * 
 * Synchronous receive data is reported as complete frames. To accomplish
 * this, the TTY flip buffer is bypassed (too small to hold largest
 * frame and may fragment frames) and the line discipline
 * receive entry point is called directly.
 *
 * This driver has been tested with a slightly modified ppp.c driver
 * for synchronous PPP.
 *
 * 2000/02/16
 * Added interface for syncppp.c driver (an alternate synchronous PPP
 * implementation that also supports Cisco HDLC). Each device instance
 * registers as a tty device AND a network device (if dosyncppp option
 * is set for the device). The functionality is determined by which
 * device interface is opened.
 *
 * 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.
 */

#if defined(__i386__)
#  define BREAKPOINT() asm("   int $3");
#else
#  define BREAKPOINT() { }
#endif

#define MAX_ISA_DEVICES 10
#define MAX_PCI_DEVICES 10
#define MAX_TOTAL_DEVICES 20

#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/delay.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/synclink.h>

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

#if defined(CONFIG_HDLC) || (defined(CONFIG_HDLC_MODULE) && defined(CONFIG_SYNCLINK_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 <linux/uaccess.h>

#define RCLRVALUE 0xffff

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; */
};

#define SHARED_MEM_ADDRESS_SIZE 0x40000
#define BUFFERLISTSIZE 4096
#define DMABUFFERSIZE 4096
#define MAXRXFRAMES 7

typedef struct _DMABUFFERENTRY
{
        u32 phys_addr;  /* 32-bit flat physical address of data buffer */
        volatile u16 count;     /* buffer size/data count */
        volatile u16 status;    /* Control/status field */
        volatile u16 rcc;       /* character count field */
        u16 reserved;   /* padding required by 16C32 */
        u32 link;       /* 32-bit flat link to next buffer entry */
        char *virt_addr;        /* virtual address of data buffer */
        u32 phys_entry; /* physical address of this buffer entry */
        dma_addr_t dma_addr;
} DMABUFFERENTRY, *DMAPBUFFERENTRY;

/* 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;
};

/* transmit holding buffer definitions*/
#define MAX_TX_HOLDING_BUFFERS 5
struct tx_holding_buffer {
        int     buffer_size;
        unsigned char * buffer;
};


/*
 * Device instance data structure
 */
 
struct mgsl_struct {
        int                     magic;
        struct tty_port         port;
        int                     line;
        int                     hw_version;
        
        struct mgsl_icount      icount;
        
        int                     timeout;
        int                     x_char;         /* xon/xoff character */
        u16                     read_status_mask;
        u16                     ignore_status_mask;     
        unsigned char           *xmit_buf;
        int                     xmit_head;
        int                     xmit_tail;
        int                     xmit_cnt;
        
        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 mgsl_struct      *next_device;   /* device list link */
        
        spinlock_t irq_spinlock;                /* spinlock for synchronizing with ISR */
        struct work_struct task;                /* task structure for scheduling bh */

        u32 EventMask;                  /* event trigger mask */
        u32 RecordedEvents;             /* pending events */

        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 */
        u32 buffer_list_phys;
        dma_addr_t buffer_list_dma_addr;

        unsigned int rx_buffer_count;   /* count of total allocated Rx buffers */
        DMABUFFERENTRY *rx_buffer_list; /* list of receive buffer entries */
        unsigned int current_rx_buffer;

        int num_tx_dma_buffers;         /* number of tx dma frames required */
        int tx_dma_buffers_used;
        unsigned int tx_buffer_count;   /* count of total allocated Tx buffers */
        DMABUFFERENTRY *tx_buffer_list; /* list of transmit buffer entries */
        int start_tx_dma_buffer;        /* tx dma buffer to start tx dma operation */
        int current_tx_buffer;          /* next tx dma buffer to be loaded */
        
        unsigned char *intermediate_rxbuffer;

        int num_tx_holding_buffers;     /* number of tx holding buffer allocated */
        int get_tx_holding_index;       /* next tx holding buffer for adapter to load */
        int put_tx_holding_index;       /* next tx holding buffer to store user request */
        int tx_holding_count;           /* number of tx holding buffers waiting */
        struct tx_holding_buffer tx_holding_buffers[MAX_TX_HOLDING_BUFFERS];

        bool rx_enabled;
        bool rx_overflow;
        bool rx_rcc_underrun;

        bool tx_enabled;
        bool tx_active;
        u32 idle_mode;

        u16 cmr_value;
        u16 tcsr_value;

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

        unsigned int bus_type;  /* expansion bus type (ISA,EISA,PCI) */
        unsigned char bus;              /* expansion bus number (zero based) */
        unsigned char function;         /* PCI device number */

        unsigned int io_base;           /* base I/O address of adapter */
        unsigned int io_addr_size;      /* size of the I/O address range */
        bool io_addr_requested;         /* true if I/O address requested */
        
        unsigned int irq_level;         /* interrupt level */
        unsigned long irq_flags;
        bool irq_requested;             /* true if IRQ requested */
        
        unsigned int dma_level;         /* DMA channel */
        bool dma_requested;             /* true if dma channel requested */

        u16 mbre_bit;
        u16 loopback_bits;
        u16 usc_idle_mode;

        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                 (DIAGS) */
        int     fDiagnosticsmode;       /* Driver in Diagnostic mode?                   (DIAGS) */

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

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

        u32 misc_ctrl_value;
        char *flag_buf;
        bool drop_rts_on_tx_done;

        bool loopmode_insert_requested;
        bool loopmode_send_done_requested;
        
        struct  _input_signal_events    input_signal_events;

        /* generic HDLC device parts */
        int netcount;
        spinlock_t netlock;

#if SYNCLINK_GENERIC_HDLC
        struct net_device *netdev;
#endif
};

#define MGSL_MAGIC 0x5401

/*
 * The size of the serial xmit buffer is 1 page, or 4096 bytes
 */
#ifndef SERIAL_XMIT_SIZE
#define SERIAL_XMIT_SIZE 4096
#endif

/*
 * These macros define the offsets used in calculating the
 * I/O address of the specified USC registers.
 */


#define DCPIN 2         /* Bit 1 of I/O address */
#define SDPIN 4         /* Bit 2 of I/O address */

#define DCAR 0          /* DMA command/address register */
#define CCAR SDPIN              /* channel command/address register */
#define DATAREG DCPIN + SDPIN   /* serial data register */
#define MSBONLY 0x41
#define LSBONLY 0x40

/*
 * These macros define the register address (ordinal number)
 * used for writing address/value pairs to the USC.
 */

#define CMR     0x02    /* Channel mode Register */
#define CCSR    0x04    /* Channel Command/status Register */
#define CCR     0x06    /* Channel Control Register */
#define PSR     0x08    /* Port status Register */
#define PCR     0x0a    /* Port Control Register */
#define TMDR    0x0c    /* Test mode Data Register */
#define TMCR    0x0e    /* Test mode Control Register */
#define CMCR    0x10    /* Clock mode Control Register */
#define HCR     0x12    /* Hardware Configuration Register */
#define IVR     0x14    /* Interrupt Vector Register */
#define IOCR    0x16    /* Input/Output Control Register */
#define ICR     0x18    /* Interrupt Control Register */
#define DCCR    0x1a    /* Daisy Chain Control Register */
#define MISR    0x1c    /* Misc Interrupt status Register */
#define SICR    0x1e    /* status Interrupt Control Register */
#define RDR     0x20    /* Receive Data Register */
#define RMR     0x22    /* Receive mode Register */
#define RCSR    0x24    /* Receive Command/status Register */
#define RICR    0x26    /* Receive Interrupt Control Register */
#define RSR     0x28    /* Receive Sync Register */
#define RCLR    0x2a    /* Receive count Limit Register */
#define RCCR    0x2c    /* Receive Character count Register */
#define TC0R    0x2e    /* Time Constant 0 Register */
#define TDR     0x30    /* Transmit Data Register */
#define TMR     0x32    /* Transmit mode Register */
#define TCSR    0x34    /* Transmit Command/status Register */
#define TICR    0x36    /* Transmit Interrupt Control Register */
#define TSR     0x38    /* Transmit Sync Register */
#define TCLR    0x3a    /* Transmit count Limit Register */
#define TCCR    0x3c    /* Transmit Character count Register */
#define TC1R    0x3e    /* Time Constant 1 Register */


/*
 * MACRO DEFINITIONS FOR DMA REGISTERS
 */

#define DCR     0x06    /* DMA Control Register (shared) */
#define DACR    0x08    /* DMA Array count Register (shared) */
#define BDCR    0x12    /* Burst/Dwell Control Register (shared) */
#define DIVR    0x14    /* DMA Interrupt Vector Register (shared) */    
#define DICR    0x18    /* DMA Interrupt Control Register (shared) */
#define CDIR    0x1a    /* Clear DMA Interrupt Register (shared) */
#define SDIR    0x1c    /* Set DMA Interrupt Register (shared) */

#define TDMR    0x02    /* Transmit DMA mode Register */
#define TDIAR   0x1e    /* Transmit DMA Interrupt Arm Register */
#define TBCR    0x2a    /* Transmit Byte count Register */
#define TARL    0x2c    /* Transmit Address Register (low) */
#define TARU    0x2e    /* Transmit Address Register (high) */
#define NTBCR   0x3a    /* Next Transmit Byte count Register */
#define NTARL   0x3c    /* Next Transmit Address Register (low) */
#define NTARU   0x3e    /* Next Transmit Address Register (high) */

#define RDMR    0x82    /* Receive DMA mode Register (non-shared) */
#define RDIAR   0x9e    /* Receive DMA Interrupt Arm Register */
#define RBCR    0xaa    /* Receive Byte count Register */
#define RARL    0xac    /* Receive Address Register (low) */
#define RARU    0xae    /* Receive Address Register (high) */
#define NRBCR   0xba    /* Next Receive Byte count Register */
#define NRARL   0xbc    /* Next Receive Address Register (low) */
#define NRARU   0xbe    /* Next Receive Address Register (high) */


/*
 * MACRO DEFINITIONS FOR MODEM STATUS BITS
 */

#define MODEMSTATUS_DTR 0x80
#define MODEMSTATUS_DSR 0x40
#define MODEMSTATUS_RTS 0x20
#define MODEMSTATUS_CTS 0x10
#define MODEMSTATUS_RI  0x04
#define MODEMSTATUS_DCD 0x01


/*
 * Channel Command/Address Register (CCAR) Command Codes
 */

#define RTCmd_Null                      0x0000
#define RTCmd_ResetHighestIus           0x1000
#define RTCmd_TriggerChannelLoadDma     0x2000
#define RTCmd_TriggerRxDma              0x2800
#define RTCmd_TriggerTxDma              0x3000
#define RTCmd_TriggerRxAndTxDma         0x3800
#define RTCmd_PurgeRxFifo               0x4800
#define RTCmd_PurgeTxFifo               0x5000
#define RTCmd_PurgeRxAndTxFifo          0x5800
#define RTCmd_LoadRcc                   0x6800
#define RTCmd_LoadTcc                   0x7000
#define RTCmd_LoadRccAndTcc             0x7800
#define RTCmd_LoadTC0                   0x8800
#define RTCmd_LoadTC1                   0x9000
#define RTCmd_LoadTC0AndTC1             0x9800
#define RTCmd_SerialDataLSBFirst        0xa000
#define RTCmd_SerialDataMSBFirst        0xa800
#define RTCmd_SelectBigEndian           0xb000
#define RTCmd_SelectLittleEndian        0xb800


/*
 * DMA Command/Address Register (DCAR) Command Codes
 */

#define DmaCmd_Null                     0x0000
#define DmaCmd_ResetTxChannel           0x1000
#define DmaCmd_ResetRxChannel           0x1200
#define DmaCmd_StartTxChannel           0x2000
#define DmaCmd_StartRxChannel           0x2200
#define DmaCmd_ContinueTxChannel        0x3000
#define DmaCmd_ContinueRxChannel        0x3200
#define DmaCmd_PauseTxChannel           0x4000
#define DmaCmd_PauseRxChannel           0x4200
#define DmaCmd_AbortTxChannel           0x5000
#define DmaCmd_AbortRxChannel           0x5200
#define DmaCmd_InitTxChannel            0x7000
#define DmaCmd_InitRxChannel            0x7200
#define DmaCmd_ResetHighestDmaIus       0x8000
#define DmaCmd_ResetAllChannels         0x9000
#define DmaCmd_StartAllChannels         0xa000
#define DmaCmd_ContinueAllChannels      0xb000
#define DmaCmd_PauseAllChannels         0xc000
#define DmaCmd_AbortAllChannels         0xd000
#define DmaCmd_InitAllChannels          0xf000

#define TCmd_Null                       0x0000
#define TCmd_ClearTxCRC                 0x2000
#define TCmd_SelectTicrTtsaData         0x4000
#define TCmd_SelectTicrTxFifostatus     0x5000
#define TCmd_SelectTicrIntLevel         0x6000
#define TCmd_SelectTicrdma_level                0x7000
#define TCmd_SendFrame                  0x8000
#define TCmd_SendAbort                  0x9000
#define TCmd_EnableDleInsertion         0xc000
#define TCmd_DisableDleInsertion        0xd000
#define TCmd_ClearEofEom                0xe000
#define TCmd_SetEofEom                  0xf000

#define RCmd_Null                       0x0000
#define RCmd_ClearRxCRC                 0x2000
#define RCmd_EnterHuntmode              0x3000
#define RCmd_SelectRicrRtsaData         0x4000
#define RCmd_SelectRicrRxFifostatus     0x5000
#define RCmd_SelectRicrIntLevel         0x6000
#define RCmd_SelectRicrdma_level                0x7000

/*
 * Bits for enabling and disabling IRQs in Interrupt Control Register (ICR)
 */
 
#define RECEIVE_STATUS          BIT5
#define RECEIVE_DATA            BIT4
#define TRANSMIT_STATUS         BIT3
#define TRANSMIT_DATA           BIT2
#define IO_PIN                  BIT1
#define MISC                    BIT0


/*
 * Receive status Bits in Receive Command/status Register RCSR
 */

#define RXSTATUS_SHORT_FRAME            BIT8
#define RXSTATUS_CODE_VIOLATION         BIT8
#define RXSTATUS_EXITED_HUNT            BIT7
#define RXSTATUS_IDLE_RECEIVED          BIT6
#define RXSTATUS_BREAK_RECEIVED         BIT5
#define RXSTATUS_ABORT_RECEIVED         BIT5
#define RXSTATUS_RXBOUND                BIT4
#define RXSTATUS_CRC_ERROR              BIT3
#define RXSTATUS_FRAMING_ERROR          BIT3
#define RXSTATUS_ABORT                  BIT2
#define RXSTATUS_PARITY_ERROR           BIT2
#define RXSTATUS_OVERRUN                BIT1
#define RXSTATUS_DATA_AVAILABLE         BIT0
#define RXSTATUS_ALL                    0x01f6
#define usc_UnlatchRxstatusBits(a,b) usc_OutReg( (a), RCSR, (u16)((b) & RXSTATUS_ALL) )

/*
 * Values for setting transmit idle mode in 
 * Transmit Control/status Register (TCSR)
 */
#define IDLEMODE_FLAGS                  0x0000
#define IDLEMODE_ALT_ONE_ZERO           0x0100
#define IDLEMODE_ZERO                   0x0200
#define IDLEMODE_ONE                    0x0300
#define IDLEMODE_ALT_MARK_SPACE         0x0500
#define IDLEMODE_SPACE                  0x0600
#define IDLEMODE_MARK                   0x0700
#define IDLEMODE_MASK                   0x0700

/*
 * IUSC revision identifiers
 */
#define IUSC_SL1660                     0x4d44
#define IUSC_PRE_SL1660                 0x4553

/*
 * Transmit status Bits in Transmit Command/status Register (TCSR)
 */

#define TCSR_PRESERVE                   0x0F00

#define TCSR_UNDERWAIT                  BIT11
#define TXSTATUS_PREAMBLE_SENT          BIT7
#define TXSTATUS_IDLE_SENT              BIT6
#define TXSTATUS_ABORT_SENT             BIT5
#define TXSTATUS_EOF_SENT               BIT4
#define TXSTATUS_EOM_SENT               BIT4
#define TXSTATUS_CRC_SENT               BIT3
#define TXSTATUS_ALL_SENT               BIT2
#define TXSTATUS_UNDERRUN               BIT1
#define TXSTATUS_FIFO_EMPTY             BIT0
#define TXSTATUS_ALL                    0x00fa
#define usc_UnlatchTxstatusBits(a,b) usc_OutReg( (a), TCSR, (u16)((a)->tcsr_value + ((b) & 0x00FF)) )
                                

#define MISCSTATUS_RXC_LATCHED          BIT15
#define MISCSTATUS_RXC                  BIT14
#define MISCSTATUS_TXC_LATCHED          BIT13
#define MISCSTATUS_TXC                  BIT12
#define MISCSTATUS_RI_LATCHED           BIT11
#define MISCSTATUS_RI                   BIT10
#define MISCSTATUS_DSR_LATCHED          BIT9
#define MISCSTATUS_DSR                  BIT8
#define MISCSTATUS_DCD_LATCHED          BIT7
#define MISCSTATUS_DCD                  BIT6
#define MISCSTATUS_CTS_LATCHED          BIT5
#define MISCSTATUS_CTS                  BIT4
#define MISCSTATUS_RCC_UNDERRUN         BIT3
#define MISCSTATUS_DPLL_NO_SYNC         BIT2
#define MISCSTATUS_BRG1_ZERO            BIT1
#define MISCSTATUS_BRG0_ZERO            BIT0

#define usc_UnlatchIostatusBits(a,b) usc_OutReg((a),MISR,(u16)((b) & 0xaaa0))
#define usc_UnlatchMiscstatusBits(a,b) usc_OutReg((a),MISR,(u16)((b) & 0x000f))

#define SICR_RXC_ACTIVE                 BIT15
#define SICR_RXC_INACTIVE               BIT14
#define SICR_RXC                        (BIT15|BIT14)
#define SICR_TXC_ACTIVE                 BIT13
#define SICR_TXC_INACTIVE               BIT12
#define SICR_TXC                        (BIT13|BIT12)
#define SICR_RI_ACTIVE                  BIT11
#define SICR_RI_INACTIVE                BIT10
#define SICR_RI                         (BIT11|BIT10)
#define SICR_DSR_ACTIVE                 BIT9
#define SICR_DSR_INACTIVE               BIT8
#define SICR_DSR                        (BIT9|BIT8)
#define SICR_DCD_ACTIVE                 BIT7
#define SICR_DCD_INACTIVE               BIT6
#define SICR_DCD                        (BIT7|BIT6)
#define SICR_CTS_ACTIVE                 BIT5
#define SICR_CTS_INACTIVE               BIT4
#define SICR_CTS                        (BIT5|BIT4)
#define SICR_RCC_UNDERFLOW              BIT3
#define SICR_DPLL_NO_SYNC               BIT2
#define SICR_BRG1_ZERO                  BIT1
#define SICR_BRG0_ZERO                  BIT0

void usc_DisableMasterIrqBit( struct mgsl_struct *info );
void usc_EnableMasterIrqBit( struct mgsl_struct *info );
void usc_EnableInterrupts( struct mgsl_struct *info, u16 IrqMask );
void usc_DisableInterrupts( struct mgsl_struct *info, u16 IrqMask );
void usc_ClearIrqPendingBits( struct mgsl_struct *info, u16 IrqMask );

#define usc_EnableInterrupts( a, b ) \
        usc_OutReg( (a), ICR, (u16)((usc_InReg((a),ICR) & 0xff00) + 0xc0 + (b)) )

#define usc_DisableInterrupts( a, b ) \
        usc_OutReg( (a), ICR, (u16)((usc_InReg((a),ICR) & 0xff00) + 0x80 + (b)) )

#define usc_EnableMasterIrqBit(a) \
        usc_OutReg( (a), ICR, (u16)((usc_InReg((a),ICR) & 0x0f00) + 0xb000) )

#define usc_DisableMasterIrqBit(a) \
        usc_OutReg( (a), ICR, (u16)(usc_InReg((a),ICR) & 0x7f00) )

#define usc_ClearIrqPendingBits( a, b ) usc_OutReg( (a), DCCR, 0x40 + (b) )

/*
 * Transmit status Bits in Transmit Control status Register (TCSR)
 * and Transmit Interrupt Control Register (TICR) (except BIT2, BIT0)
 */

#define TXSTATUS_PREAMBLE_SENT  BIT7
#define TXSTATUS_IDLE_SENT      BIT6
#define TXSTATUS_ABORT_SENT     BIT5
#define TXSTATUS_EOF            BIT4
#define TXSTATUS_CRC_SENT       BIT3
#define TXSTATUS_ALL_SENT       BIT2
#define TXSTATUS_UNDERRUN       BIT1
#define TXSTATUS_FIFO_EMPTY     BIT0

#define DICR_MASTER             BIT15
#define DICR_TRANSMIT           BIT0
#define DICR_RECEIVE            BIT1

#define usc_EnableDmaInterrupts(a,b) \
        usc_OutDmaReg( (a), DICR, (u16)(usc_InDmaReg((a),DICR) | (b)) )

#define usc_DisableDmaInterrupts(a,b) \
        usc_OutDmaReg( (a), DICR, (u16)(usc_InDmaReg((a),DICR) & ~(b)) )

#define usc_EnableStatusIrqs(a,b) \
        usc_OutReg( (a), SICR, (u16)(usc_InReg((a),SICR) | (b)) )

#define usc_DisablestatusIrqs(a,b) \
        usc_OutReg( (a), SICR, (u16)(usc_InReg((a),SICR) & ~(b)) )

/* Transmit status Bits in Transmit Control status Register (TCSR) */
/* and Transmit Interrupt Control Register (TICR) (except BIT2, BIT0) */


#define DISABLE_UNCONDITIONAL    0
#define DISABLE_END_OF_FRAME     1
#define ENABLE_UNCONDITIONAL     2
#define ENABLE_AUTO_CTS          3
#define ENABLE_AUTO_DCD          3
#define usc_EnableTransmitter(a,b) \
        usc_OutReg( (a), TMR, (u16)((usc_InReg((a),TMR) & 0xfffc) | (b)) )
#define usc_EnableReceiver(a,b) \
        usc_OutReg( (a), RMR, (u16)((usc_InReg((a),RMR) & 0xfffc) | (b)) )

static u16  usc_InDmaReg( struct mgsl_struct *info, u16 Port );
static void usc_OutDmaReg( struct mgsl_struct *info, u16 Port, u16 Value );
static void usc_DmaCmd( struct mgsl_struct *info, u16 Cmd );

static u16  usc_InReg( struct mgsl_struct *info, u16 Port );
static void usc_OutReg( struct mgsl_struct *info, u16 Port, u16 Value );
static void usc_RTCmd( struct mgsl_struct *info, u16 Cmd );
void usc_RCmd( struct mgsl_struct *info, u16 Cmd );
void usc_TCmd( struct mgsl_struct *info, u16 Cmd );

#define usc_TCmd(a,b) usc_OutReg((a), TCSR, (u16)((a)->tcsr_value + (b)))
#define usc_RCmd(a,b) usc_OutReg((a), RCSR, (b))

#define usc_SetTransmitSyncChars(a,s0,s1) usc_OutReg((a), TSR, (u16)(((u16)s0<<8)|(u16)s1))

static void usc_process_rxoverrun_sync( struct mgsl_struct *info );
static void usc_start_receiver( struct mgsl_struct *info );
static void usc_stop_receiver( struct mgsl_struct *info );

static void usc_start_transmitter( struct mgsl_struct *info );
static void usc_stop_transmitter( struct mgsl_struct *info );
static void usc_set_txidle( struct mgsl_struct *info );
static void usc_load_txfifo( struct mgsl_struct *info );

static void usc_enable_aux_clock( struct mgsl_struct *info, u32 DataRate );
static void usc_enable_loopback( struct mgsl_struct *info, int enable );

static void usc_get_serial_signals( struct mgsl_struct *info );
static void usc_set_serial_signals( struct mgsl_struct *info );

static void usc_reset( struct mgsl_struct *info );

static void usc_set_sync_mode( struct mgsl_struct *info );
static void usc_set_sdlc_mode( struct mgsl_struct *info );
static void usc_set_async_mode( struct mgsl_struct *info );
static void usc_enable_async_clock( struct mgsl_struct *info, u32 DataRate );

static void usc_loopback_frame( struct mgsl_struct *info );

static void mgsl_tx_timeout(struct timer_list *t);


static void usc_loopmode_cancel_transmit( struct mgsl_struct * info );
static void usc_loopmode_insert_request( struct mgsl_struct * info );
static int usc_loopmode_active( struct mgsl_struct * info);
static void usc_loopmode_send_done( struct mgsl_struct * info );

static int mgsl_ioctl_common(struct mgsl_struct *info, unsigned int cmd, unsigned long arg);

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

/*
 * Defines a BUS descriptor value for the PCI adapter
 * local bus address ranges.
 */

#define BUS_DESCRIPTOR( WrHold, WrDly, RdDly, Nwdd, Nwad, Nxda, Nrdd, Nrad ) \
(0x00400020 + \
((WrHold) << 30) + \
((WrDly)  << 28) + \
((RdDly)  << 26) + \
((Nwdd)   << 20) + \
((Nwad)   << 15) + \
((Nxda)   << 13) + \
((Nrdd)   << 11) + \
((Nrad)   <<  6) )

static void mgsl_trace_block(struct mgsl_struct *info,const char* data, int count, int xmit);

/*
 * Adapter diagnostic routines
 */
static bool mgsl_register_test( struct mgsl_struct *info );
static bool mgsl_irq_test( struct mgsl_struct *info );
static bool mgsl_dma_test( struct mgsl_struct *info );
static bool mgsl_memory_test( struct mgsl_struct *info );
static int mgsl_adapter_test( struct mgsl_struct *info );

/*
 * device and resource management routines
 */
static int mgsl_claim_resources(struct mgsl_struct *info);
static void mgsl_release_resources(struct mgsl_struct *info);
static void mgsl_add_device(struct mgsl_struct *info);
static struct mgsl_struct* mgsl_allocate_device(void);

/*
 * DMA buffer manupulation functions.
 */
static void mgsl_free_rx_frame_buffers( struct mgsl_struct *info, unsigned int StartIndex, unsigned int EndIndex );
static bool mgsl_get_rx_frame( struct mgsl_struct *info );
static bool mgsl_get_raw_rx_frame( struct mgsl_struct *info );
static void mgsl_reset_rx_dma_buffers( struct mgsl_struct *info );
static void mgsl_reset_tx_dma_buffers( struct mgsl_struct *info );
static int num_free_tx_dma_buffers(struct mgsl_struct *info);
static void mgsl_load_tx_dma_buffer( struct mgsl_struct *info, const char *Buffer, unsigned int BufferSize);
static void mgsl_load_pci_memory(char* TargetPtr, const char* SourcePtr, unsigned short count);

/*
 * DMA and Shared Memory buffer allocation and formatting
 */
static int  mgsl_allocate_dma_buffers(struct mgsl_struct *info);
static void mgsl_free_dma_buffers(struct mgsl_struct *info);
static int  mgsl_alloc_frame_memory(struct mgsl_struct *info, DMABUFFERENTRY *BufferList,int Buffercount);
static void mgsl_free_frame_memory(struct mgsl_struct *info, DMABUFFERENTRY *BufferList,int Buffercount);
static int  mgsl_alloc_buffer_list_memory(struct mgsl_struct *info);
static void mgsl_free_buffer_list_memory(struct mgsl_struct *info);
static int mgsl_alloc_intermediate_rxbuffer_memory(struct mgsl_struct *info);
static void mgsl_free_intermediate_rxbuffer_memory(struct mgsl_struct *info);
static int mgsl_alloc_intermediate_txbuffer_memory(struct mgsl_struct *info);
static void mgsl_free_intermediate_txbuffer_memory(struct mgsl_struct *info);
static bool load_next_tx_holding_buffer(struct mgsl_struct *info);
static int save_tx_buffer_request(struct mgsl_struct *info,const char *Buffer, unsigned int BufferSize);

/*
 * Bottom half interrupt handlers
 */
static void mgsl_bh_handler(struct work_struct *work);
static void mgsl_bh_receive(struct mgsl_struct *info);
static void mgsl_bh_transmit(struct mgsl_struct *info);
static void mgsl_bh_status(struct mgsl_struct *info);

/*
 * Interrupt handler routines and dispatch table.
 */
static void mgsl_isr_null( struct mgsl_struct *info );
static void mgsl_isr_transmit_data( struct mgsl_struct *info );
static void mgsl_isr_receive_data( struct mgsl_struct *info );
static void mgsl_isr_receive_status( struct mgsl_struct *info );
static void mgsl_isr_transmit_status( struct mgsl_struct *info );
static void mgsl_isr_io_pin( struct mgsl_struct *info );
static void mgsl_isr_misc( struct mgsl_struct *info );
static void mgsl_isr_receive_dma( struct mgsl_struct *info );
static void mgsl_isr_transmit_dma( struct mgsl_struct *info );

typedef void (*isr_dispatch_func)(struct mgsl_struct *);

static isr_dispatch_func UscIsrTable[7] =
{
        mgsl_isr_null,
        mgsl_isr_misc,
        mgsl_isr_io_pin,
        mgsl_isr_transmit_data,
        mgsl_isr_transmit_status,
        mgsl_isr_receive_data,
        mgsl_isr_receive_status
};

/*
 * ioctl call handlers
 */
static int tiocmget(struct tty_struct *tty);
static int tiocmset(struct tty_struct *tty,
                    unsigned int set, unsigned int clear);
static int mgsl_get_stats(struct mgsl_struct * info, struct mgsl_icount
        __user *user_icount);
static int mgsl_get_params(struct mgsl_struct * info, MGSL_PARAMS  __user *user_params);
static int mgsl_set_params(struct mgsl_struct * info, MGSL_PARAMS  __user *new_params);
static int mgsl_get_txidle(struct mgsl_struct * info, int __user *idle_mode);
static int mgsl_set_txidle(struct mgsl_struct * info, int idle_mode);
static int mgsl_txenable(struct mgsl_struct * info, int enable);
static int mgsl_txabort(struct mgsl_struct * info);
static int mgsl_rxenable(struct mgsl_struct * info, int enable);
static int mgsl_wait_event(struct mgsl_struct * info, int __user *mask);
static int mgsl_loopmode_send_done( struct mgsl_struct * info );

/* set non-zero on successful registration with PCI subsystem */
static bool pci_registered;

/*
 * Global linked list of SyncLink devices
 */
static struct mgsl_struct *mgsl_device_list;
static int mgsl_device_count;

/*
 * Set this param to non-zero to load eax with the
 * .text section address and breakpoint on module load.
 * This is useful for use with gdb and add-symbol-file command.
 */
static bool break_on_load;

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

/*
 * Array of user specified options for ISA adapters.
 */
static int io[MAX_ISA_DEVICES];
static int irq[MAX_ISA_DEVICES];
static int dma[MAX_ISA_DEVICES];
static int debug_level;
static int maxframe[MAX_TOTAL_DEVICES];
static int txdmabufs[MAX_TOTAL_DEVICES];
static int txholdbufs[MAX_TOTAL_DEVICES];
        
module_param(break_on_load, bool, 0);
module_param(ttymajor, int, 0);
module_param_hw_array(io, int, ioport, NULL, 0);
module_param_hw_array(irq, int, irq, NULL, 0);
module_param_hw_array(dma, int, dma, NULL, 0);
module_param(debug_level, int, 0);
module_param_array(maxframe, int, NULL, 0);
module_param_array(txdmabufs, int, NULL, 0);
module_param_array(txholdbufs, int, NULL, 0);

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

static int synclink_init_one (struct pci_dev *dev,
                                     const struct pci_device_id *ent);
static void synclink_remove_one (struct pci_dev *dev);

static const struct pci_device_id synclink_pci_tbl[] = {
        { PCI_VENDOR_ID_MICROGATE, PCI_DEVICE_ID_MICROGATE_USC, PCI_ANY_ID, PCI_ANY_ID, },
        { PCI_VENDOR_ID_MICROGATE, 0x0210, PCI_ANY_ID, PCI_ANY_ID, },
        { 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, synclink_pci_tbl);

MODULE_LICENSE("GPL");

static struct pci_driver synclink_pci_driver = {
        .name           = "synclink",
        .id_table       = synclink_pci_tbl,
        .probe          = synclink_init_one,
        .remove         = synclink_remove_one,
};

static struct tty_driver *serial_driver;

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


static void mgsl_change_params(struct mgsl_struct *info);
static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout);

/*
 * 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* mgsl_get_text_ptr(void)
{
        return mgsl_get_text_ptr;
}

static inline int mgsl_paranoia_check(struct mgsl_struct *info,
                                        char *name, const char *routine)
{
#ifdef MGSL_PARANOIA_CHECK
        static const char *badmagic =
                "Warning: bad magic number for mgsl struct (%s) in %s\n";
        static const char *badinfo =
                "Warning: null mgsl_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);
        }
}

/* mgsl_stop()          throttle (stop) transmitter
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_stop(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_stop"))
                return;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("mgsl_stop(%s)\n",info->device_name);    
                
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (info->tx_enabled)
                usc_stop_transmitter(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
}       /* end of mgsl_stop() */

/* mgsl_start()         release (start) transmitter
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_start(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;

        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_start"))
                return;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("mgsl_start(%s)\n",info->device_name);   
                
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (!info->tx_enabled)
                usc_start_transmitter(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
}       /* end of mgsl_start() */

/*
 * Bottom half work queue access functions
 */

/* mgsl_bh_action()     Return next bottom half action to perform.
 * Return Value:        BH action code or 0 if nothing to do.
 */
static int mgsl_bh_action(struct mgsl_struct *info)
{
        unsigned long flags;
        int rc = 0;
        
        spin_lock_irqsave(&info->irq_spinlock,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->irq_spinlock,flags);
        
        return rc;
}

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

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

        while((action = mgsl_bh_action(info)) != 0) {
        
                /* Process work item */
                if ( debug_level >= DEBUG_LEVEL_BH )
                        printk( "%s(%d):mgsl_bh_handler() work item action=%d\n",
                                __FILE__,__LINE__,action);

                switch (action) {
                
                case BH_RECEIVE:
                        mgsl_bh_receive(info);
                        break;
                case BH_TRANSMIT:
                        mgsl_bh_transmit(info);
                        break;
                case BH_STATUS:
                        mgsl_bh_status(info);
                        break;
                default:
                        /* unknown work item ID */
                        printk("Unknown work item ID=%08X!\n", action);
                        break;
                }
        }

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

static void mgsl_bh_receive(struct mgsl_struct *info)
{
        bool (*get_rx_frame)(struct mgsl_struct *info) =
                (info->params.mode == MGSL_MODE_HDLC ? mgsl_get_rx_frame : mgsl_get_raw_rx_frame);

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_receive(%s)\n",
                        __FILE__,__LINE__,info->device_name);
        
        do
        {
                if (info->rx_rcc_underrun) {
                        unsigned long flags;
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        usc_start_receiver(info);
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        return;
                }
        } while(get_rx_frame(info));
}

static void mgsl_bh_transmit(struct mgsl_struct *info)
{
        struct tty_struct *tty = info->port.tty;
        unsigned long flags;
        
        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_transmit() entry on %s\n",
                        __FILE__,__LINE__,info->device_name);

        if (tty)
                tty_wakeup(tty);

        /* if transmitter idle and loopmode_send_done_requested
         * then start echoing RxD to TxD
         */
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( !info->tx_active && info->loopmode_send_done_requested )
                usc_loopmode_send_done( info );
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
}

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

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

/* mgsl_isr_receive_status()
 * 
 *      Service a receive status interrupt. The type of status
 *      interrupt is indicated by the state of the RCSR.
 *      This is only used for HDLC mode.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_receive_status( struct mgsl_struct *info )
{
        u16 status = usc_InReg( info, RCSR );

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):mgsl_isr_receive_status status=%04X\n",
                        __FILE__,__LINE__,status);
                        
        if ( (status & RXSTATUS_ABORT_RECEIVED) && 
                info->loopmode_insert_requested &&
                usc_loopmode_active(info) )
        {
                ++info->icount.rxabort;
                info->loopmode_insert_requested = false;
 
                /* clear CMR:13 to start echoing RxD to TxD */
                info->cmr_value &= ~BIT13;
                usc_OutReg(info, CMR, info->cmr_value);
 
                /* disable received abort irq (no longer required) */
                usc_OutReg(info, RICR,
                        (usc_InReg(info, RICR) & ~RXSTATUS_ABORT_RECEIVED));
        }

        if (status & (RXSTATUS_EXITED_HUNT | RXSTATUS_IDLE_RECEIVED)) {
                if (status & RXSTATUS_EXITED_HUNT)
                        info->icount.exithunt++;
                if (status & RXSTATUS_IDLE_RECEIVED)
                        info->icount.rxidle++;
                wake_up_interruptible(&info->event_wait_q);
        }

        if (status & RXSTATUS_OVERRUN){
                info->icount.rxover++;
                usc_process_rxoverrun_sync( info );
        }

        usc_ClearIrqPendingBits( info, RECEIVE_STATUS );
        usc_UnlatchRxstatusBits( info, status );

}       /* end of mgsl_isr_receive_status() */

/* mgsl_isr_transmit_status()
 * 
 *      Service a transmit status interrupt
 *      HDLC mode :end of transmit frame
 *      Async mode:all data is sent
 *      transmit status is indicated by bits in the TCSR.
 * 
 * Arguments:           info           pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_transmit_status( struct mgsl_struct *info )
{
        u16 status = usc_InReg( info, TCSR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_transmit_status status=%04X\n",
                        __FILE__,__LINE__,status);
        
        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS );
        usc_UnlatchTxstatusBits( info, status );
        
        if ( status & (TXSTATUS_UNDERRUN | TXSTATUS_ABORT_SENT) )
        {
                /* finished sending HDLC abort. This may leave  */
                /* the TxFifo with data from the aborted frame  */
                /* so purge the TxFifo. Also shutdown the DMA   */
                /* channel in case there is data remaining in   */
                /* the DMA buffer                               */
                usc_DmaCmd( info, DmaCmd_ResetTxChannel );
                usc_RTCmd( info, RTCmd_PurgeTxFifo );
        }
 
        if ( status & TXSTATUS_EOF_SENT )
                info->icount.txok++;
        else if ( status & TXSTATUS_UNDERRUN )
                info->icount.txunder++;
        else if ( status & TXSTATUS_ABORT_SENT )
                info->icount.txabort++;
        else
                info->icount.txunder++;
                        
        info->tx_active = false;
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        del_timer(&info->tx_timer);     
        
        if ( info->drop_rts_on_tx_done ) {
                usc_get_serial_signals( info );
                if ( info->serial_signals & SerialSignal_RTS ) {
                        info->serial_signals &= ~SerialSignal_RTS;
                        usc_set_serial_signals( info );
                }
                info->drop_rts_on_tx_done = false;
        }

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

}       /* end of mgsl_isr_transmit_status() */

/* mgsl_isr_io_pin()
 * 
 *      Service an Input/Output pin interrupt. The type of
 *      interrupt is indicated by bits in the MISR
 *      
 * Arguments:           info           pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_io_pin( struct mgsl_struct *info )
{
        struct  mgsl_icount *icount;
        u16 status = usc_InReg( info, MISR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_io_pin status=%04X\n",
                        __FILE__,__LINE__,status);
                        
        usc_ClearIrqPendingBits( info, IO_PIN );
        usc_UnlatchIostatusBits( info, 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) {
                        if ((info->ri_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
                                usc_DisablestatusIrqs(info,SICR_RI);
                        icount->rng++;
                        if ( status & MISCSTATUS_RI )
                                info->input_signal_events.ri_up++;      
                        else
                                info->input_signal_events.ri_down++;    
                }
                if (status & MISCSTATUS_DSR_LATCHED) {
                        if ((info->dsr_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
                                usc_DisablestatusIrqs(info,SICR_DSR);
                        icount->dsr++;
                        if ( status & MISCSTATUS_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)
                                usc_DisablestatusIrqs(info,SICR_DCD);
                        icount->dcd++;
                        if (status & MISCSTATUS_DCD) {
                                info->input_signal_events.dcd_up++;
                        } else
                                info->input_signal_events.dcd_down++;
#if SYNCLINK_GENERIC_HDLC
                        if (info->netcount) {
                                if (status & MISCSTATUS_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)
                                usc_DisablestatusIrqs(info,SICR_CTS);
                        icount->cts++;
                        if ( status & MISCSTATUS_CTS )
                                info->input_signal_events.cts_up++;
                        else
                                info->input_signal_events.cts_down++;
                }
                wake_up_interruptible(&info->status_event_wait_q);
                wake_up_interruptible(&info->event_wait_q);

                if (tty_port_check_carrier(&info->port) &&
                     (status & MISCSTATUS_DCD_LATCHED) ) {
                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                printk("%s CD now %s...", info->device_name,
                                       (status & MISCSTATUS_DCD) ? "on" : "off");
                        if (status & MISCSTATUS_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->hw_stopped) {
                                if (status & MISCSTATUS_CTS) {
                                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                                printk("CTS tx start...");
                                        info->port.tty->hw_stopped = 0;
                                        usc_start_transmitter(info);
                                        info->pending_bh |= BH_TRANSMIT;
                                        return;
                                }
                        } else {
                                if (!(status & MISCSTATUS_CTS)) {
                                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                                printk("CTS tx stop...");
                                        if (info->port.tty)
                                                info->port.tty->hw_stopped = 1;
                                        usc_stop_transmitter(info);
                                }
                        }
                }
        }

        info->pending_bh |= BH_STATUS;
        
        /* for diagnostics set IRQ flag */
        if ( status & MISCSTATUS_TXC_LATCHED ){
                usc_OutReg( info, SICR,
                        (unsigned short)(usc_InReg(info,SICR) & ~(SICR_TXC_ACTIVE+SICR_TXC_INACTIVE)) );
                usc_UnlatchIostatusBits( info, MISCSTATUS_TXC_LATCHED );
                info->irq_occurred = true;
        }

}       /* end of mgsl_isr_io_pin() */

/* mgsl_isr_transmit_data()
 * 
 *      Service a transmit data interrupt (async mode only).
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_transmit_data( struct mgsl_struct *info )
{
        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_transmit_data xmit_cnt=%d\n",
                        __FILE__,__LINE__,info->xmit_cnt);
                        
        usc_ClearIrqPendingBits( info, TRANSMIT_DATA );
        
        if (info->port.tty->stopped || info->port.tty->hw_stopped) {
                usc_stop_transmitter(info);
                return;
        }
        
        if ( info->xmit_cnt )
                usc_load_txfifo( info );
        else
                info->tx_active = false;
                
        if (info->xmit_cnt < WAKEUP_CHARS)
                info->pending_bh |= BH_TRANSMIT;

}       /* end of mgsl_isr_transmit_data() */

/* mgsl_isr_receive_data()
 * 
 *      Service a receive data interrupt. This occurs
 *      when operating in asynchronous interrupt transfer mode.
 *      The receive data FIFO is flushed to the receive data buffers. 
 * 
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_receive_data( struct mgsl_struct *info )
{
        int Fifocount;
        u16 status;
        int work = 0;
        unsigned char DataByte;
        struct  mgsl_icount *icount = &info->icount;
        
        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_receive_data\n",
                        __FILE__,__LINE__);

        usc_ClearIrqPendingBits( info, RECEIVE_DATA );
        
        /* select FIFO status for RICR readback */
        usc_RCmd( info, RCmd_SelectRicrRxFifostatus );

        /* clear the Wordstatus bit so that status readback */
        /* only reflects the status of this byte */
        usc_OutReg( info, RICR+LSBONLY, (u16)(usc_InReg(info, RICR+LSBONLY) & ~BIT3 ));

        /* flush the receive FIFO */

        while( (Fifocount = (usc_InReg(info,RICR) >> 8)) ) {
                int flag;

                /* read one byte from RxFIFO */
                outw( (inw(info->io_base + CCAR) & 0x0780) | (RDR+LSBONLY),
                      info->io_base + CCAR );
                DataByte = inb( info->io_base + CCAR );

                /* get the status of the received byte */
                status = usc_InReg(info, RCSR);
                if ( status & (RXSTATUS_FRAMING_ERROR | RXSTATUS_PARITY_ERROR |
                                RXSTATUS_OVERRUN | RXSTATUS_BREAK_RECEIVED) )
                        usc_UnlatchRxstatusBits(info,RXSTATUS_ALL);
                
                icount->rx++;
                
                flag = 0;
                if ( status & (RXSTATUS_FRAMING_ERROR | RXSTATUS_PARITY_ERROR |
                                RXSTATUS_OVERRUN | RXSTATUS_BREAK_RECEIVED) ) {
                        printk("rxerr=%04X\n",status);
                        /* update error statistics */
                        if ( status & RXSTATUS_BREAK_RECEIVED ) {
                                status &= ~(RXSTATUS_FRAMING_ERROR | RXSTATUS_PARITY_ERROR);
                                icount->brk++;
                        } else if (status & RXSTATUS_PARITY_ERROR)
                                icount->parity++;
                        else if (status & RXSTATUS_FRAMING_ERROR)
                                icount->frame++;
                        else if (status & RXSTATUS_OVERRUN) {
                                /* must issue purge fifo cmd before */
                                /* 16C32 accepts more receive chars */
                                usc_RTCmd(info,RTCmd_PurgeRxFifo);
                                icount->overrun++;
                        }

                        /* discard char if tty control flags say so */
                        if (status & info->ignore_status_mask)
                                continue;
                                
                        status &= info->read_status_mask;
                
                        if (status & RXSTATUS_BREAK_RECEIVED) {
                                flag = TTY_BREAK;
                                if (info->port.flags & ASYNC_SAK)
                                        do_SAK(info->port.tty);
                        } else if (status & RXSTATUS_PARITY_ERROR)
                                flag = TTY_PARITY;
                        else if (status & RXSTATUS_FRAMING_ERROR)
                                flag = TTY_FRAME;
                }       /* end of if (error) */
                tty_insert_flip_char(&info->port, DataByte, flag);
                if (status & RXSTATUS_OVERRUN) {
                        /* Overrun is special, since it's
                         * reported immediately, and doesn't
                         * affect the current character
                         */
                        work += tty_insert_flip_char(&info->port, 0, TTY_OVERRUN);
                }
        }

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

/* mgsl_isr_misc()
 * 
 *      Service a miscellaneous interrupt source.
 *      
 * Arguments:           info            pointer to device extension (instance data)
 * Return Value:        None
 */
static void mgsl_isr_misc( struct mgsl_struct *info )
{
        u16 status = usc_InReg( info, MISR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_misc status=%04X\n",
                        __FILE__,__LINE__,status);
                        
        if ((status & MISCSTATUS_RCC_UNDERRUN) &&
            (info->params.mode == MGSL_MODE_HDLC)) {

                /* turn off receiver and rx DMA */
                usc_EnableReceiver(info,DISABLE_UNCONDITIONAL);
                usc_DmaCmd(info, DmaCmd_ResetRxChannel);
                usc_UnlatchRxstatusBits(info, RXSTATUS_ALL);
                usc_ClearIrqPendingBits(info, RECEIVE_DATA | RECEIVE_STATUS);
                usc_DisableInterrupts(info, RECEIVE_DATA | RECEIVE_STATUS);

                /* schedule BH handler to restart receiver */
                info->pending_bh |= BH_RECEIVE;
                info->rx_rcc_underrun = true;
        }

        usc_ClearIrqPendingBits( info, MISC );
        usc_UnlatchMiscstatusBits( info, status );

}       /* end of mgsl_isr_misc() */

/* mgsl_isr_null()
 *
 *      Services undefined interrupt vectors from the
 *      USC. (hence this function SHOULD never be called)
 * 
 * Arguments:           info            pointer to device extension (instance data)
 * Return Value:        None
 */
static void mgsl_isr_null( struct mgsl_struct *info )
{

}       /* end of mgsl_isr_null() */

/* mgsl_isr_receive_dma()
 * 
 *      Service a receive DMA channel interrupt.
 *      For this driver there are two sources of receive DMA interrupts
 *      as identified in the Receive DMA mode Register (RDMR):
 * 
 *      BIT3    EOA/EOL         End of List, all receive buffers in receive
 *                              buffer list have been filled (no more free buffers
 *                              available). The DMA controller has shut down.
 * 
 *      BIT2    EOB             End of Buffer. This interrupt occurs when a receive
 *                              DMA buffer is terminated in response to completion
 *                              of a good frame or a frame with errors. The status
 *                              of the frame is stored in the buffer entry in the
 *                              list of receive buffer entries.
 * 
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_receive_dma( struct mgsl_struct *info )
{
        u16 status;
        
        /* clear interrupt pending and IUS bit for Rx DMA IRQ */
        usc_OutDmaReg( info, CDIR, BIT9 | BIT1 );

        /* Read the receive DMA status to identify interrupt type. */
        /* This also clears the status bits. */
        status = usc_InDmaReg( info, RDMR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_receive_dma(%s) status=%04X\n",
                        __FILE__,__LINE__,info->device_name,status);
                        
        info->pending_bh |= BH_RECEIVE;
        
        if ( status & BIT3 ) {
                info->rx_overflow = true;
                info->icount.buf_overrun++;
        }

}       /* end of mgsl_isr_receive_dma() */

/* mgsl_isr_transmit_dma()
 *
 *      This function services a transmit DMA channel interrupt.
 *
 *      For this driver there is one source of transmit DMA interrupts
 *      as identified in the Transmit DMA Mode Register (TDMR):
 *
 *      BIT2  EOB       End of Buffer. This interrupt occurs when a
 *                      transmit DMA buffer has been emptied.
 *
 *      The driver maintains enough transmit DMA buffers to hold at least
 *      one max frame size transmit frame. When operating in a buffered
 *      transmit mode, there may be enough transmit DMA buffers to hold at
 *      least two or more max frame size frames. On an EOB condition,
 *      determine if there are any queued transmit buffers and copy into
 *      transmit DMA buffers if we have room.
 *
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_transmit_dma( struct mgsl_struct *info )
{
        u16 status;

        /* clear interrupt pending and IUS bit for Tx DMA IRQ */
        usc_OutDmaReg(info, CDIR, BIT8 | BIT0 );

        /* Read the transmit DMA status to identify interrupt type. */
        /* This also clears the status bits. */

        status = usc_InDmaReg( info, TDMR );

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

        if ( status & BIT2 ) {
                --info->tx_dma_buffers_used;

                /* if there are transmit frames queued,
                 *  try to load the next one
                 */
                if ( load_next_tx_holding_buffer(info) ) {
                        /* if call returns non-zero value, we have
                         * at least one free tx holding buffer
                         */
                        info->pending_bh |= BH_TRANSMIT;
                }
        }

}       /* end of mgsl_isr_transmit_dma() */

/* mgsl_interrupt()
 * 
 *      Interrupt service routine entry point.
 *      
 * Arguments:
 * 
 *      irq             interrupt number that caused interrupt
 *      dev_id          device ID supplied during interrupt registration
 *      
 * Return Value: None
 */
static irqreturn_t mgsl_interrupt(int dummy, void *dev_id)
{
        struct mgsl_struct *info = dev_id;
        u16 UscVector;
        u16 DmaVector;

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

        spin_lock(&info->irq_spinlock);

        for(;;) {
                /* Read the interrupt vectors from hardware. */
                UscVector = usc_InReg(info, IVR) >> 9;
                DmaVector = usc_InDmaReg(info, DIVR);
                
                if ( debug_level >= DEBUG_LEVEL_ISR )   
                        printk("%s(%d):%s UscVector=%08X DmaVector=%08X\n",
                                __FILE__,__LINE__,info->device_name,UscVector,DmaVector);
                        
                if ( !UscVector && !DmaVector )
                        break;
                        
                /* Dispatch interrupt vector */
                if ( UscVector )
                        (*UscIsrTable[UscVector])(info);
                else if ( (DmaVector&(BIT10|BIT9)) == BIT10)
                        mgsl_isr_transmit_dma(info);
                else
                        mgsl_isr_receive_dma(info);

                if ( info->isr_overflow ) {
                        printk(KERN_ERR "%s(%d):%s isr overflow irq=%d\n",
                                __FILE__, __LINE__, info->device_name, info->irq_level);
                        usc_DisableMasterIrqBit(info);
                        usc_DisableDmaInterrupts(info,DICR_MASTER);
                        break;
                }
        }
        
        /* Request bottom half processing if there's something 
         * for it to do and the bh is not already running
         */

        if ( info->pending_bh && !info->bh_running && !info->bh_requested ) {
                if ( debug_level >= DEBUG_LEVEL_ISR )   
                        printk("%s(%d):%s queueing bh task.\n",
                                __FILE__,__LINE__,info->device_name);
                schedule_work(&info->task);
                info->bh_requested = true;
        }

        spin_unlock(&info->irq_spinlock);
        
        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk(KERN_DEBUG "%s(%d):mgsl_interrupt(%d)exit.\n",
                        __FILE__, __LINE__, info->irq_level);

        return IRQ_HANDLED;
}       /* end of mgsl_interrupt() */

/* startup()
 * 
 *      Initialize and start device.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        0 if success, otherwise error code
 */
static int startup(struct mgsl_struct * info)
{
        int retval = 0;

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

        if (tty_port_initialized(&info->port))
                return 0;

        if (!info->xmit_buf) {
                /* allocate a page of memory for a transmit buffer */
                info->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
                if (!info->xmit_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));

        timer_setup(&info->tx_timer, mgsl_tx_timeout, 0);
        
        /* Allocate and claim adapter resources */
        retval = mgsl_claim_resources(info);
        
        /* perform existence check and diagnostics */
        if ( !retval )
                retval = mgsl_adapter_test(info);
                
        if ( retval ) {
                if (capable(CAP_SYS_ADMIN) && info->port.tty)
                        set_bit(TTY_IO_ERROR, &info->port.tty->flags);
                mgsl_release_resources(info);
                return retval;
        }

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

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

        tty_port_set_initialized(&info->port, 1);

        return 0;
}       /* end of startup() */

/* shutdown()
 *
 * Called by mgsl_close() and mgsl_hangup() to shutdown hardware
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void shutdown(struct mgsl_struct * info)
{
        unsigned long flags;

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

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_shutdown(%s)\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_sync(&info->tx_timer);

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

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_DisableMasterIrqBit(info);
        usc_stop_receiver(info);
        usc_stop_transmitter(info);
        usc_DisableInterrupts(info,RECEIVE_DATA | RECEIVE_STATUS |
                TRANSMIT_DATA | TRANSMIT_STATUS | IO_PIN | MISC );
        usc_DisableDmaInterrupts(info,DICR_MASTER + DICR_TRANSMIT + DICR_RECEIVE);

        /* Disable DMAEN (Port 7, Bit 14) */
        /* This disconnects the DMA request signal from the ISA bus */
        /* on the ISA adapter. This has no effect for the PCI adapter */
        usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT15) | BIT14));

        /* Disable INTEN (Port 6, Bit12) */
        /* This disconnects the IRQ request signal to the ISA bus */
        /* on the ISA adapter. This has no effect for the PCI adapter */
        usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT13) | BIT12));

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

        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        mgsl_release_resources(info);

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

        tty_port_set_initialized(&info->port, 0);
}       /* end of shutdown() */

static void mgsl_program_hw(struct mgsl_struct *info)
{
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        
        usc_stop_receiver(info);
        usc_stop_transmitter(info);
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        
        if (info->params.mode == MGSL_MODE_HDLC ||
            info->params.mode == MGSL_MODE_RAW ||
            info->netcount)
                usc_set_sync_mode(info);
        else
                usc_set_async_mode(info);
                
        usc_set_serial_signals(info);
        
        info->dcd_chkcount = 0;
        info->cts_chkcount = 0;
        info->ri_chkcount = 0;
        info->dsr_chkcount = 0;

        usc_EnableStatusIrqs(info,SICR_CTS+SICR_DSR+SICR_DCD+SICR_RI);
        usc_EnableInterrupts(info, IO_PIN);
        usc_get_serial_signals(info);
                
        if (info->netcount || info->port.tty->termios.c_cflag & CREAD)
                usc_start_receiver(info);
                
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
}

/* Reconfigure adapter based on new parameters
 */
static void mgsl_change_params(struct mgsl_struct *info)
{
        unsigned cflag;
        int bits_per_char;

        if (!info->port.tty)
                return;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_change_params(%s)\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 */

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

        /* process tty input control flags */
        
        info->read_status_mask = RXSTATUS_OVERRUN;
        if (I_INPCK(info->port.tty))
                info->read_status_mask |= RXSTATUS_PARITY_ERROR | RXSTATUS_FRAMING_ERROR;
        if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
                info->read_status_mask |= RXSTATUS_BREAK_RECEIVED;
        
        if (I_IGNPAR(info->port.tty))
                info->ignore_status_mask |= RXSTATUS_PARITY_ERROR | RXSTATUS_FRAMING_ERROR;
        if (I_IGNBRK(info->port.tty)) {
                info->ignore_status_mask |= RXSTATUS_BREAK_RECEIVED;
                /* If ignoring parity and break indicators, ignore 
                 * overruns too.  (For real raw support).
                 */
                if (I_IGNPAR(info->port.tty))
                        info->ignore_status_mask |= RXSTATUS_OVERRUN;
        }

        mgsl_program_hw(info);

}       /* end of mgsl_change_params() */

/* mgsl_put_char()
 * 
 *      Add a character to the transmit buffer.
 *      
 * Arguments:           tty     pointer to tty information structure
 *                      ch      character to add to transmit buffer
 *              
 * Return Value:        None
 */
static int mgsl_put_char(struct tty_struct *tty, unsigned char ch)

{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        int ret = 0;

        if (debug_level >= DEBUG_LEVEL_INFO) {
                printk(KERN_DEBUG "%s(%d):mgsl_put_char(%d) on %s\n",
                        __FILE__, __LINE__, ch, info->device_name);
        }               
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_put_char"))
                return 0;

        if (!info->xmit_buf)
                return 0;

        spin_lock_irqsave(&info->irq_spinlock, flags);
        
        if ((info->params.mode == MGSL_MODE_ASYNC ) || !info->tx_active) {
                if (info->xmit_cnt < SERIAL_XMIT_SIZE - 1) {
                        info->xmit_buf[info->xmit_head++] = ch;
                        info->xmit_head &= SERIAL_XMIT_SIZE-1;
                        info->xmit_cnt++;
                        ret = 1;
                }
        }
        spin_unlock_irqrestore(&info->irq_spinlock, flags);
        return ret;
        
}       /* end of mgsl_put_char() */

/* mgsl_flush_chars()
 * 
 *      Enable transmitter so remaining characters in the
 *      transmit buffer are sent.
 *      
 * Arguments:           tty     pointer to tty information structure
 * Return Value:        None
 */
static void mgsl_flush_chars(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
                                
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_flush_chars() entry on %s xmit_cnt=%d\n",
                        __FILE__,__LINE__,info->device_name,info->xmit_cnt);
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_flush_chars"))
                return;

        if (info->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
            !info->xmit_buf)
                return;

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

        spin_lock_irqsave(&info->irq_spinlock,flags);
        
        if (!info->tx_active) {
                if ( (info->params.mode == MGSL_MODE_HDLC ||
                        info->params.mode == MGSL_MODE_RAW) && info->xmit_cnt ) {
                        /* operating in synchronous (frame oriented) mode */
                        /* copy data from circular xmit_buf to */
                        /* transmit DMA buffer. */
                        mgsl_load_tx_dma_buffer(info,
                                 info->xmit_buf,info->xmit_cnt);
                }
                usc_start_transmitter(info);
        }
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
}       /* end of mgsl_flush_chars() */

/* mgsl_write()
 * 
 *      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 mgsl_write(struct tty_struct * tty,
                    const unsigned char *buf, int count)
{
        int     c, ret = 0;
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_write(%s) count=%d\n",
                        __FILE__,__LINE__,info->device_name,count);
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_write"))
                goto cleanup;

        if (!info->xmit_buf)
                goto cleanup;

        if ( info->params.mode == MGSL_MODE_HDLC ||
                        info->params.mode == MGSL_MODE_RAW ) {
                /* operating in synchronous (frame oriented) mode */
                if (info->tx_active) {

                        if ( info->params.mode == MGSL_MODE_HDLC ) {
                                ret = 0;
                                goto cleanup;
                        }
                        /* transmitter is actively sending data -
                         * if we have multiple transmit dma and
                         * holding buffers, attempt to queue this
                         * frame for transmission at a later time.
                         */
                        if (info->tx_holding_count >= info->num_tx_holding_buffers ) {
                                /* no tx holding buffers available */
                                ret = 0;
                                goto cleanup;
                        }

                        /* queue transmit frame request */
                        ret = count;
                        save_tx_buffer_request(info,buf,count);

                        /* if we have sufficient tx dma buffers,
                         * load the next buffered tx request
                         */
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        load_next_tx_holding_buffer(info);
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        goto cleanup;
                }
        
                /* if operating in HDLC LoopMode and the adapter  */
                /* has yet to be inserted into the loop, we can't */
                /* transmit                                       */

                if ( (info->params.flags & HDLC_FLAG_HDLC_LOOPMODE) &&
                        !usc_loopmode_active(info) )
                {
                        ret = 0;
                        goto cleanup;
                }

                if ( info->xmit_cnt ) {
                        /* Send accumulated from send_char() calls */
                        /* as frame and wait before accepting more data. */
                        ret = 0;
                        
                        /* copy data from circular xmit_buf to */
                        /* transmit DMA buffer. */
                        mgsl_load_tx_dma_buffer(info,
                                info->xmit_buf,info->xmit_cnt);
                        if ( debug_level >= DEBUG_LEVEL_INFO )
                                printk( "%s(%d):mgsl_write(%s) sync xmit_cnt flushing\n",
                                        __FILE__,__LINE__,info->device_name);
                } else {
                        if ( debug_level >= DEBUG_LEVEL_INFO )
                                printk( "%s(%d):mgsl_write(%s) sync transmit accepted\n",
                                        __FILE__,__LINE__,info->device_name);
                        ret = count;
                        info->xmit_cnt = count;
                        mgsl_load_tx_dma_buffer(info,buf,count);
                }
        } else {
                while (1) {
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        c = min_t(int, count,
                                min(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
                                    SERIAL_XMIT_SIZE - info->xmit_head));
                        if (c <= 0) {
                                spin_unlock_irqrestore(&info->irq_spinlock,flags);
                                break;
                        }
                        memcpy(info->xmit_buf + info->xmit_head, buf, c);
                        info->xmit_head = ((info->xmit_head + c) &
                                           (SERIAL_XMIT_SIZE-1));
                        info->xmit_cnt += c;
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        buf += c;
                        count -= c;
                        ret += c;
                }
        }       
        
        if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                if (!info->tx_active)
                        usc_start_transmitter(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
cleanup:        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_write(%s) returning=%d\n",
                        __FILE__,__LINE__,info->device_name,ret);
                        
        return ret;
        
}       /* end of mgsl_write() */

/* mgsl_write_room()
 *
 *      Return the count of free bytes in transmit buffer
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static int mgsl_write_room(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        int     ret;
                                
        if (mgsl_paranoia_check(info, tty->name, "mgsl_write_room"))
                return 0;
        ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;
        if (ret < 0)
                ret = 0;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_write_room(%s)=%d\n",
                         __FILE__,__LINE__, info->device_name,ret );
                         
        if ( info->params.mode == MGSL_MODE_HDLC ||
                info->params.mode == MGSL_MODE_RAW ) {
                /* operating in synchronous (frame oriented) mode */
                if ( info->tx_active )
                        return 0;
                else
                        return HDLC_MAX_FRAME_SIZE;
        }
        
        return ret;
        
}       /* end of mgsl_write_room() */

/* mgsl_chars_in_buffer()
 *
 *      Return the count of bytes in transmit buffer
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static int mgsl_chars_in_buffer(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
                         
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_chars_in_buffer(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_chars_in_buffer"))
                return 0;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_chars_in_buffer(%s)=%d\n",
                         __FILE__,__LINE__, info->device_name,info->xmit_cnt );
                         
        if ( info->params.mode == MGSL_MODE_HDLC ||
                info->params.mode == MGSL_MODE_RAW ) {
                /* operating in synchronous (frame oriented) mode */
                if ( info->tx_active )
                        return info->max_frame_size;
                else
                        return 0;
        }
                         
        return info->xmit_cnt;
}       /* end of mgsl_chars_in_buffer() */

/* mgsl_flush_buffer()
 *
 *      Discard all data in the send buffer
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_flush_buffer(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_flush_buffer(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_flush_buffer"))
                return;
                
        spin_lock_irqsave(&info->irq_spinlock,flags); 
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        del_timer(&info->tx_timer);     
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        tty_wakeup(tty);
}

/* mgsl_send_xchar()
 *
 *      Send a high-priority XON/XOFF character
 *      
 * Arguments:           tty     pointer to tty info structure
 *                      ch      character to send
 * Return Value:        None
 */
static void mgsl_send_xchar(struct tty_struct *tty, char ch)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_send_xchar(%s,%d)\n",
                         __FILE__,__LINE__, info->device_name, ch );
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_send_xchar"))
                return;

        info->x_char = ch;
        if (ch) {
                /* Make sure transmit interrupts are on */
                spin_lock_irqsave(&info->irq_spinlock,flags);
                if (!info->tx_enabled)
                        usc_start_transmitter(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
}       /* end of mgsl_send_xchar() */

/* mgsl_throttle()
 * 
 *      Signal remote device to throttle send data (our receive data)
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_throttle(struct tty_struct * tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_throttle(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (mgsl_paranoia_check(info, tty->name, "mgsl_throttle"))
                return;
        
        if (I_IXOFF(tty))
                mgsl_send_xchar(tty, STOP_CHAR(tty));

        if (C_CRTSCTS(tty)) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                info->serial_signals &= ~SerialSignal_RTS;
                usc_set_serial_signals(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
}       /* end of mgsl_throttle() */

/* mgsl_unthrottle()
 * 
 *      Signal remote device to stop throttling send data (our receive data)
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_unthrottle(struct tty_struct * tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_unthrottle(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (mgsl_paranoia_check(info, tty->name, "mgsl_unthrottle"))
                return;
        
        if (I_IXOFF(tty)) {
                if (info->x_char)
                        info->x_char = 0;
                else
                        mgsl_send_xchar(tty, START_CHAR(tty));
        }

        if (C_CRTSCTS(tty)) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                info->serial_signals |= SerialSignal_RTS;
                usc_set_serial_signals(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
        
}       /* end of mgsl_unthrottle() */

/* mgsl_get_stats()
 * 
 *      get the current serial parameters information
 *
 * Arguments:   info            pointer to device instance data
 *              user_icount     pointer to buffer to hold returned stats
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_get_stats(struct mgsl_struct * info, struct mgsl_icount __user *user_icount)
{
        int err;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_get_params(%s)\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;
        
}       /* end of mgsl_get_stats() */

/* mgsl_get_params()
 * 
 *      get the current serial parameters information
 *
 * Arguments:   info            pointer to device instance data
 *              user_params     pointer to buffer to hold returned params
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_get_params(struct mgsl_struct * info, MGSL_PARAMS __user *user_params)
{
        int err;
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_get_params(%s)\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):mgsl_get_params(%s) user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }
        
        return 0;
        
}       /* end of mgsl_get_params() */

/* mgsl_set_params()
 * 
 *      set the serial parameters
 *      
 * Arguments:
 * 
 *      info            pointer to device instance data
 *      new_params      user buffer containing new serial params
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_set_params(struct mgsl_struct * info, MGSL_PARAMS __user *new_params)
{
        unsigned long flags;
        MGSL_PARAMS tmp_params;
        int err;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_set_params %s\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):mgsl_set_params(%s) user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }
        
        mutex_lock(&info->port.mutex);
        spin_lock_irqsave(&info->irq_spinlock,flags);
        memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        mgsl_change_params(info);
        mutex_unlock(&info->port.mutex);
        
        return 0;
        
}       /* end of mgsl_set_params() */

/* mgsl_get_txidle()
 * 
 *      get the current transmit idle mode
 *
 * Arguments:   info            pointer to device instance data
 *              idle_mode       pointer to buffer to hold returned idle mode
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_get_txidle(struct mgsl_struct * info, int __user *idle_mode)
{
        int err;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_get_txidle(%s)=%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):mgsl_get_txidle(%s) user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }
        
        return 0;
        
}       /* end of mgsl_get_txidle() */

/* mgsl_set_txidle()    service ioctl to set transmit idle mode
 *      
 * Arguments:           info            pointer to device instance data
 *                      idle_mode       new idle mode
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_set_txidle(struct mgsl_struct * info, int idle_mode)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_set_txidle(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, idle_mode );
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        info->idle_mode = idle_mode;
        usc_set_txidle( info );
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_set_txidle() */

/* mgsl_txenable()
 * 
 *      enable or disable the transmitter
 *      
 * Arguments:
 * 
 *      info            pointer to device instance data
 *      enable          1 = enable, 0 = disable
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_txenable(struct mgsl_struct * info, int enable)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_txenable(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, enable);
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( enable ) {
                if ( !info->tx_enabled ) {

                        usc_start_transmitter(info);
                        /*--------------------------------------------------
                         * if HDLC/SDLC Loop mode, attempt to insert the
                         * station in the 'loop' by setting CMR:13. Upon
                         * receipt of the next GoAhead (RxAbort) sequence,
                         * the OnLoop indicator (CCSR:7) should go active
                         * to indicate that we are on the loop
                         *--------------------------------------------------*/
                        if ( info->params.flags & HDLC_FLAG_HDLC_LOOPMODE )
                                usc_loopmode_insert_request( info );
                }
        } else {
                if ( info->tx_enabled )
                        usc_stop_transmitter(info);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_txenable() */

/* mgsl_txabort()       abort send HDLC frame
 *      
 * Arguments:           info            pointer to device instance data
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_txabort(struct mgsl_struct * info)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_txabort(%s)\n", __FILE__,__LINE__,
                        info->device_name);
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( info->tx_active && info->params.mode == MGSL_MODE_HDLC )
        {
                if ( info->params.flags & HDLC_FLAG_HDLC_LOOPMODE )
                        usc_loopmode_cancel_transmit( info );
                else
                        usc_TCmd(info,TCmd_SendAbort);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_txabort() */

/* mgsl_rxenable()      enable or disable the receiver
 *      
 * Arguments:           info            pointer to device instance data
 *                      enable          1 = enable, 0 = disable
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_rxenable(struct mgsl_struct * info, int enable)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_rxenable(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, enable);
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( enable ) {
                if ( !info->rx_enabled )
                        usc_start_receiver(info);
        } else {
                if ( info->rx_enabled )
                        usc_stop_receiver(info);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_rxenable() */

/* mgsl_wait_event()    wait for specified event to occur
 *      
 * Arguments:           info    pointer to device instance data
 *                      mask    pointer to bitmask of events to wait for
 * Return Value:        0       if successful and bit mask updated with
 *                              of events triggerred,
 *                      otherwise error code
 */
static int mgsl_wait_event(struct mgsl_struct * info, int __user * mask_ptr)
{
        unsigned long flags;
        int s;
        int rc=0;
        struct mgsl_icount cprev, cnow;
        int events;
        int mask;
        struct  _input_signal_events oldsigs, newsigs;
        DECLARE_WAITQUEUE(wait, current);

        COPY_FROM_USER(rc,&mask, mask_ptr, sizeof(int));
        if (rc) {
                return  -EFAULT;
        }
                 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_wait_event(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, mask);

        spin_lock_irqsave(&info->irq_spinlock,flags);

        /* return immediately if state matches requested events */
        usc_get_serial_signals(info);
        s = info->serial_signals;
        events = mask &
                ( ((s & SerialSignal_DSR) ? MgslEvent_DsrActive:MgslEvent_DsrInactive) +
                  ((s & SerialSignal_DCD) ? MgslEvent_DcdActive:MgslEvent_DcdInactive) +
                  ((s & SerialSignal_CTS) ? MgslEvent_CtsActive:MgslEvent_CtsInactive) +
                  ((s & SerialSignal_RI)  ? MgslEvent_RiActive :MgslEvent_RiInactive) );
        if (events) {
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
                goto exit;
        }

        /* save current irq counts */
        cprev = info->icount;
        oldsigs = info->input_signal_events;
        
        /* enable hunt and idle irqs if needed */
        if (mask & (MgslEvent_ExitHuntMode + MgslEvent_IdleReceived)) {
                u16 oldreg = usc_InReg(info,RICR);
                u16 newreg = oldreg +
                         (mask & MgslEvent_ExitHuntMode ? RXSTATUS_EXITED_HUNT:0) +
                         (mask & MgslEvent_IdleReceived ? RXSTATUS_IDLE_RECEIVED:0);
                if (oldreg != newreg)
                        usc_OutReg(info, RICR, newreg);
        }
        
        set_current_state(TASK_INTERRUPTIBLE);
        add_wait_queue(&info->event_wait_q, &wait);
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        

        for(;;) {
                schedule();
                if (signal_pending(current)) {
                        rc = -ERESTARTSYS;
                        break;
                }
                        
                /* get current irq counts */
                spin_lock_irqsave(&info->irq_spinlock,flags);
                cnow = info->icount;
                newsigs = info->input_signal_events;
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);

                /* if no change, wait aborted for some reason */
                if (newsigs.dsr_up   == oldsigs.dsr_up   &&
                    newsigs.dsr_down == oldsigs.dsr_down &&
                    newsigs.dcd_up   == oldsigs.dcd_up   &&
                    newsigs.dcd_down == oldsigs.dcd_down &&
                    newsigs.cts_up   == oldsigs.cts_up   &&
                    newsigs.cts_down == oldsigs.cts_down &&
                    newsigs.ri_up    == oldsigs.ri_up    &&
                    newsigs.ri_down  == oldsigs.ri_down  &&
                    cnow.exithunt    == cprev.exithunt   &&
                    cnow.rxidle      == cprev.rxidle) {
                        rc = -EIO;
                        break;
                }

                events = mask &
                        ( (newsigs.dsr_up   != oldsigs.dsr_up   ? MgslEvent_DsrActive:0)   +
                        (newsigs.dsr_down != oldsigs.dsr_down ? MgslEvent_DsrInactive:0) +
                        (newsigs.dcd_up   != oldsigs.dcd_up   ? MgslEvent_DcdActive:0)   +
                        (newsigs.dcd_down != oldsigs.dcd_down ? MgslEvent_DcdInactive:0) +
                        (newsigs.cts_up   != oldsigs.cts_up   ? MgslEvent_CtsActive:0)   +
                        (newsigs.cts_down != oldsigs.cts_down ? MgslEvent_CtsInactive:0) +
                        (newsigs.ri_up    != oldsigs.ri_up    ? MgslEvent_RiActive:0)    +
                        (newsigs.ri_down  != oldsigs.ri_down  ? MgslEvent_RiInactive:0)  +
                        (cnow.exithunt    != cprev.exithunt   ? MgslEvent_ExitHuntMode:0) +
                          (cnow.rxidle      != cprev.rxidle     ? MgslEvent_IdleReceived:0) );
                if (events)
                        break;
                
                cprev = cnow;
                oldsigs = newsigs;
        }
        
        remove_wait_queue(&info->event_wait_q, &wait);
        set_current_state(TASK_RUNNING);

        if (mask & (MgslEvent_ExitHuntMode + MgslEvent_IdleReceived)) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                if (!waitqueue_active(&info->event_wait_q)) {
                        /* disable enable exit hunt mode/idle rcvd IRQs */
                        usc_OutReg(info, RICR, usc_InReg(info,RICR) &
                                ~(RXSTATUS_EXITED_HUNT | RXSTATUS_IDLE_RECEIVED));
                }
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
exit:
        if ( rc == 0 )
                PUT_USER(rc, events, mask_ptr);
                
        return rc;
        
}       /* end of mgsl_wait_event() */

static int modem_input_wait(struct mgsl_struct *info,int arg)
{
        unsigned long flags;
        int rc;
        struct mgsl_icount cprev, cnow;
        DECLARE_WAITQUEUE(wait, current);

        /* save current irq counts */
        spin_lock_irqsave(&info->irq_spinlock,flags);
        cprev = info->icount;
        add_wait_queue(&info->status_event_wait_q, &wait);
        set_current_state(TASK_INTERRUPTIBLE);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        for(;;) {
                schedule();
                if (signal_pending(current)) {
                        rc = -ERESTARTSYS;
                        break;
                }

                /* get new irq counts */
                spin_lock_irqsave(&info->irq_spinlock,flags);
                cnow = info->icount;
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);

                /* if no change, wait aborted for some reason */
                if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
                    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
                        rc = -EIO;
                        break;
                }

                /* check for change in caller specified modem input */
                if ((arg & TIOCM_RNG && cnow.rng != cprev.rng) ||
                    (arg & TIOCM_DSR && cnow.dsr != cprev.dsr) ||
                    (arg & TIOCM_CD  && cnow.dcd != cprev.dcd) ||
                    (arg & TIOCM_CTS && cnow.cts != cprev.cts)) {
                        rc = 0;
                        break;
                }

                cprev = cnow;
        }
        remove_wait_queue(&info->status_event_wait_q, &wait);
        set_current_state(TASK_RUNNING);
        return rc;
}

/* return the state of the serial control and status signals
 */
static int tiocmget(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned int result;
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_get_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        result = ((info->serial_signals & SerialSignal_RTS) ? TIOCM_RTS:0) +
                ((info->serial_signals & SerialSignal_DTR) ? TIOCM_DTR:0) +
                ((info->serial_signals & SerialSignal_DCD) ? TIOCM_CAR:0) +
                ((info->serial_signals & SerialSignal_RI)  ? TIOCM_RNG:0) +
                ((info->serial_signals & SerialSignal_DSR) ? TIOCM_DSR:0) +
                ((info->serial_signals & SerialSignal_CTS) ? TIOCM_CTS:0);

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s tiocmget() value=%08X\n",
                         __FILE__,__LINE__, info->device_name, result );
        return result;
}

/* set modem control signals (DTR/RTS)
 */
static int tiocmset(struct tty_struct *tty,
                                    unsigned int set, unsigned int clear)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;

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

        if (set & TIOCM_RTS)
                info->serial_signals |= SerialSignal_RTS;
        if (set & TIOCM_DTR)
                info->serial_signals |= SerialSignal_DTR;
        if (clear & TIOCM_RTS)
                info->serial_signals &= ~SerialSignal_RTS;
        if (clear & TIOCM_DTR)
                info->serial_signals &= ~SerialSignal_DTR;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_set_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        return 0;
}

/* mgsl_break()         Set or clear transmit break condition
 *
 * Arguments:           tty             pointer to tty instance data
 *                      break_state     -1=set break condition, 0=clear
 * Return Value:        error code
 */
static int mgsl_break(struct tty_struct *tty, int break_state)
{
        struct mgsl_struct * info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_break(%s,%d)\n",
                         __FILE__,__LINE__, info->device_name, break_state);
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_break"))
                return -EINVAL;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (break_state == -1)
                usc_OutReg(info,IOCR,(u16)(usc_InReg(info,IOCR) | BIT7));
        else 
                usc_OutReg(info,IOCR,(u16)(usc_InReg(info,IOCR) & ~BIT7));
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_break() */

/*
 * 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.
 */
static int msgl_get_icount(struct tty_struct *tty,
                                struct serial_icounter_struct *icount)

{
        struct mgsl_struct * info = tty->driver_data;
        struct mgsl_icount cnow;        /* kernel counter temps */
        unsigned long flags;

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

/* mgsl_ioctl() 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 mgsl_ioctl(struct tty_struct *tty,
                    unsigned int cmd, unsigned long arg)
{
        struct mgsl_struct * info = tty->driver_data;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_ioctl %s cmd=%08X\n", __FILE__,__LINE__,
                        info->device_name, cmd );
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_ioctl"))
                return -ENODEV;

        if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
            (cmd != TIOCMIWAIT)) {
                if (tty_io_error(tty))
                    return -EIO;
        }

        return mgsl_ioctl_common(info, cmd, arg);
}

static int mgsl_ioctl_common(struct mgsl_struct *info, unsigned int cmd, unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        
        switch (cmd) {
                case MGSL_IOCGPARAMS:
                        return mgsl_get_params(info, argp);
                case MGSL_IOCSPARAMS:
                        return mgsl_set_params(info, argp);
                case MGSL_IOCGTXIDLE:
                        return mgsl_get_txidle(info, argp);
                case MGSL_IOCSTXIDLE:
                        return mgsl_set_txidle(info,(int)arg);
                case MGSL_IOCTXENABLE:
                        return mgsl_txenable(info,(int)arg);
                case MGSL_IOCRXENABLE:
                        return mgsl_rxenable(info,(int)arg);
                case MGSL_IOCTXABORT:
                        return mgsl_txabort(info);
                case MGSL_IOCGSTATS:
                        return mgsl_get_stats(info, argp);
                case MGSL_IOCWAITEVENT:
                        return mgsl_wait_event(info, argp);
                case MGSL_IOCLOOPTXDONE:
                        return mgsl_loopmode_send_done(info);
                /* 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);