/*
 * Device driver for Microgate SyncLink GT serial adapters.
 *
 * written by Paul Fulghum for Microgate Corporation
 * paulkf@microgate.com
 *
 * Microgate and SyncLink are trademarks of Microgate Corporation
 *
 * This code is released under the GNU General Public License (GPL)
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * DEBUG OUTPUT DEFINITIONS
 *
 * uncomment lines below to enable specific types of debug output
 *
 * DBGINFO   information - most verbose output
 * DBGERR    serious errors
 * DBGBH     bottom half service routine debugging
 * DBGISR    interrupt service routine debugging
 * DBGDATA   output receive and transmit data
 * DBGTBUF   output transmit DMA buffers and registers
 * DBGRBUF   output receive DMA buffers and registers
 */

#define DBGINFO(fmt) if (debug_level >= DEBUG_LEVEL_INFO) printk fmt
#define DBGERR(fmt) if (debug_level >= DEBUG_LEVEL_ERROR) printk fmt
#define DBGBH(fmt) if (debug_level >= DEBUG_LEVEL_BH) printk fmt
#define DBGISR(fmt) if (debug_level >= DEBUG_LEVEL_ISR) printk fmt
#define DBGDATA(info, buf, size, label) if (debug_level >= DEBUG_LEVEL_DATA) trace_block((info), (buf), (size), (label))
/*#define DBGTBUF(info) dump_tbufs(info)*/
/*#define DBGRBUF(info) dump_rbufs(info)*/


#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/ioctl.h>
#include <linux/termios.h>
#include <linux/bitops.h>
#include <linux/workqueue.h>
#include <linux/hdlc.h>
#include <linux/synclink.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/dma.h>
#include <asm/types.h>
#include <asm/uaccess.h>

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

/*
 * module identification
 */
static char *driver_name     = "SyncLink GT";
static char *slgt_driver_name = "synclink_gt";
static char *tty_dev_prefix  = "ttySLG";
MODULE_LICENSE("GPL");
#define MGSL_MAGIC 0x5401
#define MAX_DEVICES 32

static struct pci_device_id pci_table[] = {
        {PCI_VENDOR_ID_MICROGATE, SYNCLINK_GT_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
        {PCI_VENDOR_ID_MICROGATE, SYNCLINK_GT2_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
        {PCI_VENDOR_ID_MICROGATE, SYNCLINK_GT4_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
        {PCI_VENDOR_ID_MICROGATE, SYNCLINK_AC_DEVICE_ID, PCI_ANY_ID, PCI_ANY_ID,},
        {0,}, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, pci_table);

static int  init_one(struct pci_dev *dev,const struct pci_device_id *ent);
static void remove_one(struct pci_dev *dev);
static struct pci_driver pci_driver = {
        .name           = "synclink_gt",
        .id_table       = pci_table,
        .probe          = init_one,
        .remove         = remove_one,
};

static bool pci_registered;

/*
 * module configuration and status
 */
static struct slgt_info *slgt_device_list;
static int slgt_device_count;

static int ttymajor;
static int debug_level;
static int maxframe[MAX_DEVICES];

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

MODULE_PARM_DESC(ttymajor, "TTY major device number override: 0=auto assigned");
MODULE_PARM_DESC(debug_level, "Debug syslog output: 0=disabled, 1 to 5=increasing detail");
MODULE_PARM_DESC(maxframe, "Maximum frame size used by device (4096 to 65535)");

/*
 * tty support and callbacks
 */
static struct tty_driver *serial_driver;

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

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

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

/*
 * generic HDLC support and callbacks
 */
#if SYNCLINK_GENERIC_HDLC
#define dev_to_port(D) (dev_to_hdlc(D)->priv)
static void hdlcdev_tx_done(struct slgt_info *info);
static void hdlcdev_rx(struct slgt_info *info, char *buf, int size);
static int  hdlcdev_init(struct slgt_info *info);
static void hdlcdev_exit(struct slgt_info *info);
#endif


/*
 * device specific structures, macros and functions
 */

#define SLGT_MAX_PORTS 4
#define SLGT_REG_SIZE  256

/*
 * conditional wait facility
 */
struct cond_wait {
        struct cond_wait *next;
        wait_queue_head_t q;
        wait_queue_t wait;
        unsigned int data;
};
static void init_cond_wait(struct cond_wait *w, unsigned int data);
static void add_cond_wait(struct cond_wait **head, struct cond_wait *w);
static void remove_cond_wait(struct cond_wait **head, struct cond_wait *w);
static void flush_cond_wait(struct cond_wait **head);

/*
 * DMA buffer descriptor and access macros
 */
struct slgt_desc
{
        __le16 count;
        __le16 status;
        __le32 pbuf;  /* physical address of data buffer */
        __le32 next;  /* physical address of next descriptor */

        /* driver book keeping */
        char *buf;          /* virtual  address of data buffer */
        unsigned int pdesc; /* physical address of this descriptor */
        dma_addr_t buf_dma_addr;
        unsigned short buf_count;
};

#define set_desc_buffer(a,b) (a).pbuf = cpu_to_le32((unsigned int)(b))
#define set_desc_next(a,b) (a).next   = cpu_to_le32((unsigned int)(b))
#define set_desc_count(a,b)(a).count  = cpu_to_le16((unsigned short)(b))
#define set_desc_eof(a,b)  (a).status = cpu_to_le16((b) ? (le16_to_cpu((a).status) | BIT0) : (le16_to_cpu((a).status) & ~BIT0))
#define set_desc_status(a, b) (a).status = cpu_to_le16((unsigned short)(b))
#define desc_count(a)      (le16_to_cpu((a).count))
#define desc_status(a)     (le16_to_cpu((a).status))
#define desc_complete(a)   (le16_to_cpu((a).status) & BIT15)
#define desc_eof(a)        (le16_to_cpu((a).status) & BIT2)
#define desc_crc_error(a)  (le16_to_cpu((a).status) & BIT1)
#define desc_abort(a)      (le16_to_cpu((a).status) & BIT0)
#define desc_residue(a)    ((le16_to_cpu((a).status) & 0x38) >> 3)

struct _input_signal_events {
        int ri_up;
        int ri_down;
        int dsr_up;
        int dsr_down;
        int dcd_up;
        int dcd_down;
        int cts_up;
        int cts_down;
};

/*
 * device instance data structure
 */
struct slgt_info {
        void *if_ptr;           /* General purpose pointer (used by SPPP) */
        struct tty_port port;

        struct slgt_info *next_device;  /* device list link */

        int magic;

        char device_name[25];
        struct pci_dev *pdev;

        int port_count;  /* count of ports on adapter */
        int adapter_num; /* adapter instance number */
        int port_num;    /* port instance number */

        /* array of pointers to port contexts on this adapter */
        struct slgt_info *port_array[SLGT_MAX_PORTS];

        int                     line;           /* tty line instance number */

        struct mgsl_icount      icount;

        int                     timeout;
        int                     x_char;         /* xon/xoff character */
        unsigned int            read_status_mask;
        unsigned int            ignore_status_mask;

        wait_queue_head_t       status_event_wait_q;
        wait_queue_head_t       event_wait_q;
        struct timer_list       tx_timer;
        struct timer_list       rx_timer;

        unsigned int            gpio_present;
        struct cond_wait        *gpio_wait_q;

        spinlock_t lock;        /* spinlock for synchronizing with ISR */

        struct work_struct task;
        u32 pending_bh;
        bool bh_requested;
        bool bh_running;

        int isr_overflow;
        bool irq_requested;     /* true if IRQ requested */
        bool irq_occurred;      /* for diagnostics use */

        /* device configuration */

        unsigned int bus_type;
        unsigned int irq_level;
        unsigned long irq_flags;

        unsigned char __iomem * reg_addr;  /* memory mapped registers address */
        u32 phys_reg_addr;
        bool reg_addr_requested;

        MGSL_PARAMS params;       /* communications parameters */
        u32 idle_mode;
        u32 max_frame_size;       /* as set by device config */

        unsigned int rbuf_fill_level;
        unsigned int rx_pio;
        unsigned int if_mode;
        unsigned int base_clock;
        unsigned int xsync;
        unsigned int xctrl;

        /* device status */

        bool rx_enabled;
        bool rx_restart;

        bool tx_enabled;
        bool tx_active;

        unsigned char signals;    /* serial signal states */
        int init_error;  /* initialization error */

        unsigned char *tx_buf;
        int tx_count;

        char *flag_buf;
        bool drop_rts_on_tx_done;
        struct  _input_signal_events    input_signal_events;

        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 *bufs;             /* virtual address of DMA buffer lists */
        dma_addr_t bufs_dma_addr; /* physical address of buffer descriptors */

        unsigned int rbuf_count;
        struct slgt_desc *rbufs;
        unsigned int rbuf_current;
        unsigned int rbuf_index;
        unsigned int rbuf_fill_index;
        unsigned short rbuf_fill_count;

        unsigned int tbuf_count;
        struct slgt_desc *tbufs;
        unsigned int tbuf_current;
        unsigned int tbuf_start;

        unsigned char *tmp_rbuf;
        unsigned int tmp_rbuf_count;

        /* SPPP/Cisco HDLC device parts */

        int netcount;
        spinlock_t netlock;
#if SYNCLINK_GENERIC_HDLC
        struct net_device *netdev;
#endif

};

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


#define BH_RECEIVE  1
#define BH_TRANSMIT 2
#define BH_STATUS   4
#define IO_PIN_SHUTDOWN_LIMIT 100

#define DMABUFSIZE 256
#define DESC_LIST_SIZE 4096

#define MASK_PARITY  BIT1
#define MASK_FRAMING BIT0
#define MASK_BREAK   BIT14
#define MASK_OVERRUN BIT4

#define GSR   0x00 /* global status */
#define JCR   0x04 /* JTAG control */
#define IODR  0x08 /* GPIO direction */
#define IOER  0x0c /* GPIO interrupt enable */
#define IOVR  0x10 /* GPIO value */
#define IOSR  0x14 /* GPIO interrupt status */
#define TDR   0x80 /* tx data */
#define RDR   0x80 /* rx data */
#define TCR   0x82 /* tx control */
#define TIR   0x84 /* tx idle */
#define TPR   0x85 /* tx preamble */
#define RCR   0x86 /* rx control */
#define VCR   0x88 /* V.24 control */
#define CCR   0x89 /* clock control */
#define BDR   0x8a /* baud divisor */
#define SCR   0x8c /* serial control */
#define SSR   0x8e /* serial status */
#define RDCSR 0x90 /* rx DMA control/status */
#define TDCSR 0x94 /* tx DMA control/status */
#define RDDAR 0x98 /* rx DMA descriptor address */
#define TDDAR 0x9c /* tx DMA descriptor address */
#define XSR   0x40 /* extended sync pattern */
#define XCR   0x44 /* extended control */

#define RXIDLE      BIT14
#define RXBREAK     BIT14
#define IRQ_TXDATA  BIT13
#define IRQ_TXIDLE  BIT12
#define IRQ_TXUNDER BIT11 /* HDLC */
#define IRQ_RXDATA  BIT10
#define IRQ_RXIDLE  BIT9  /* HDLC */
#define IRQ_RXBREAK BIT9  /* async */
#define IRQ_RXOVER  BIT8
#define IRQ_DSR     BIT7
#define IRQ_CTS     BIT6
#define IRQ_DCD     BIT5
#define IRQ_RI      BIT4
#define IRQ_ALL     0x3ff0
#define IRQ_MASTER  BIT0

#define slgt_irq_on(info, mask) \
        wr_reg16((info), SCR, (unsigned short)(rd_reg16((info), SCR) | (mask)))
#define slgt_irq_off(info, mask) \
        wr_reg16((info), SCR, (unsigned short)(rd_reg16((info), SCR) & ~(mask)))

static __u8  rd_reg8(struct slgt_info *info, unsigned int addr);
static void  wr_reg8(struct slgt_info *info, unsigned int addr, __u8 value);
static __u16 rd_reg16(struct slgt_info *info, unsigned int addr);
static void  wr_reg16(struct slgt_info *info, unsigned int addr, __u16 value);
static __u32 rd_reg32(struct slgt_info *info, unsigned int addr);
static void  wr_reg32(struct slgt_info *info, unsigned int addr, __u32 value);

static void  msc_set_vcr(struct slgt_info *info);

static int  startup(struct slgt_info *info);
static int  block_til_ready(struct tty_struct *tty, struct file * filp,struct slgt_info *info);
static void shutdown(struct slgt_info *info);
static void program_hw(struct slgt_info *info);
static void change_params(struct slgt_info *info);

static int  register_test(struct slgt_info *info);
static int  irq_test(struct slgt_info *info);
static int  loopback_test(struct slgt_info *info);
static int  adapter_test(struct slgt_info *info);

static void reset_adapter(struct slgt_info *info);
static void reset_port(struct slgt_info *info);
static void async_mode(struct slgt_info *info);
static void sync_mode(struct slgt_info *info);

static void rx_stop(struct slgt_info *info);
static void rx_start(struct slgt_info *info);
static void reset_rbufs(struct slgt_info *info);
static void free_rbufs(struct slgt_info *info, unsigned int first, unsigned int last);
static void rdma_reset(struct slgt_info *info);
static bool rx_get_frame(struct slgt_info *info);
static bool rx_get_buf(struct slgt_info *info);

static void tx_start(struct slgt_info *info);
static void tx_stop(struct slgt_info *info);
static void tx_set_idle(struct slgt_info *info);
static unsigned int free_tbuf_count(struct slgt_info *info);
static unsigned int tbuf_bytes(struct slgt_info *info);
static void reset_tbufs(struct slgt_info *info);
static void tdma_reset(struct slgt_info *info);
static bool tx_load(struct slgt_info *info, const char *buf, unsigned int count);

static void get_signals(struct slgt_info *info);
static void set_signals(struct slgt_info *info);
static void enable_loopback(struct slgt_info *info);
static void set_rate(struct slgt_info *info, u32 data_rate);

static int  bh_action(struct slgt_info *info);
static void bh_handler(struct work_struct *work);
static void bh_transmit(struct slgt_info *info);
static void isr_serial(struct slgt_info *info);
static void isr_rdma(struct slgt_info *info);
static void isr_txeom(struct slgt_info *info, unsigned short status);
static void isr_tdma(struct slgt_info *info);

static int  alloc_dma_bufs(struct slgt_info *info);
static void free_dma_bufs(struct slgt_info *info);
static int  alloc_desc(struct slgt_info *info);
static void free_desc(struct slgt_info *info);
static int  alloc_bufs(struct slgt_info *info, struct slgt_desc *bufs, int count);
static void free_bufs(struct slgt_info *info, struct slgt_desc *bufs, int count);

static int  alloc_tmp_rbuf(struct slgt_info *info);
static void free_tmp_rbuf(struct slgt_info *info);

static void tx_timeout(unsigned long context);
static void rx_timeout(unsigned long context);

/*
 * ioctl handlers
 */
static int  get_stats(struct slgt_info *info, struct mgsl_icount __user *user_icount);
static int  get_params(struct slgt_info *info, MGSL_PARAMS __user *params);
static int  set_params(struct slgt_info *info, MGSL_PARAMS __user *params);
static int  get_txidle(struct slgt_info *info, int __user *idle_mode);
static int  set_txidle(struct slgt_info *info, int idle_mode);
static int  tx_enable(struct slgt_info *info, int enable);
static int  tx_abort(struct slgt_info *info);
static int  rx_enable(struct slgt_info *info, int enable);
static int  modem_input_wait(struct slgt_info *info,int arg);
static int  wait_mgsl_event(struct slgt_info *info, int __user *mask_ptr);
static int  tiocmget(struct tty_struct *tty);
static int  tiocmset(struct tty_struct *tty,
                                unsigned int set, unsigned int clear);
static int set_break(struct tty_struct *tty, int break_state);
static int  get_interface(struct slgt_info *info, int __user *if_mode);
static int  set_interface(struct slgt_info *info, int if_mode);
static int  set_gpio(struct slgt_info *info, struct gpio_desc __user *gpio);
static int  get_gpio(struct slgt_info *info, struct gpio_desc __user *gpio);
static int  wait_gpio(struct slgt_info *info, struct gpio_desc __user *gpio);
static int  get_xsync(struct slgt_info *info, int __user *if_mode);
static int  set_xsync(struct slgt_info *info, int if_mode);
static int  get_xctrl(struct slgt_info *info, int __user *if_mode);
static int  set_xctrl(struct slgt_info *info, int if_mode);

/*
 * driver functions
 */
static void add_device(struct slgt_info *info);
static void device_init(int adapter_num, struct pci_dev *pdev);
static int  claim_resources(struct slgt_info *info);
static void release_resources(struct slgt_info *info);

/*
 * DEBUG OUTPUT CODE
 */
#ifndef DBGINFO
#define DBGINFO(fmt)
#endif
#ifndef DBGERR
#define DBGERR(fmt)
#endif
#ifndef DBGBH
#define DBGBH(fmt)
#endif
#ifndef DBGISR
#define DBGISR(fmt)
#endif

#ifdef DBGDATA
static void trace_block(struct slgt_info *info, const char *data, int count, const char *label)
{
        int i;
        int linecount;
        printk("%s %s data:\n",info->device_name, label);
        while(count) {
                linecount = (count > 16) ? 16 : count;
                for(i=0; i < linecount; i++)
                        printk("%02X ",(unsigned char)data[i]);
                for(;i<17;i++)
                        printk("   ");
                for(i=0;i<linecount;i++) {
                        if (data[i]>=040 && data[i]<=0176)
                                printk("%c",data[i]);
                        else
                                printk(".");
                }
                printk("\n");
                data  += linecount;
                count -= linecount;
        }
}
#else
#define DBGDATA(info, buf, size, label)
#endif

#ifdef DBGTBUF
static void dump_tbufs(struct slgt_info *info)
{
        int i;
        printk("tbuf_current=%d\n", info->tbuf_current);
        for (i=0 ; i < info->tbuf_count ; i++) {
                printk("%d: count=%04X status=%04X\n",
                        i, le16_to_cpu(info->tbufs[i].count), le16_to_cpu(info->tbufs[i].status));
        }
}
#else
#define DBGTBUF(info)
#endif

#ifdef DBGRBUF
static void dump_rbufs(struct slgt_info *info)
{
        int i;
        printk("rbuf_current=%d\n", info->rbuf_current);
        for (i=0 ; i < info->rbuf_count ; i++) {
                printk("%d: count=%04X status=%04X\n",
                        i, le16_to_cpu(info->rbufs[i].count), le16_to_cpu(info->rbufs[i].status));
        }
}
#else
#define DBGRBUF(info)
#endif

static inline int sanity_check(struct slgt_info *info, char *devname, const char *name)
{
#ifdef SANITY_CHECK
        if (!info) {
                printk("null struct slgt_info for (%s) in %s\n", devname, name);
                return 1;
        }
        if (info->magic != MGSL_MAGIC) {
                printk("bad magic number struct slgt_info (%s) in %s\n", devname, name);
                return 1;
        }
#else
        if (!info)
                return 1;
#endif
        return 0;
}

/**
 * line discipline callback wrappers
 *
 * The wrappers maintain line discipline references
 * while calling into the line discipline.
 *
 * ldisc_receive_buf  - pass receive data to line discipline
 */
static void ldisc_receive_buf(struct tty_struct *tty,
                              const __u8 *data, char *flags, int count)
{
        struct tty_ldisc *ld;
        if (!tty)
                return;
        ld = tty_ldisc_ref(tty);
        if (ld) {
                if (ld->ops->receive_buf)
                        ld->ops->receive_buf(tty, data, flags, count);
                tty_ldisc_deref(ld);
        }
}

/* tty callbacks */

static int open(struct tty_struct *tty, struct file *filp)
{
        struct slgt_info *info;
        int retval, line;
        unsigned long flags;

        line = tty->index;
        if (line >= slgt_device_count) {
                DBGERR(("%s: open with invalid line #%d.\n", driver_name, line));
                return -ENODEV;
        }

        info = slgt_device_list;
        while(info && info->line != line)
                info = info->next_device;
        if (sanity_check(info, tty->name, "open"))
                return -ENODEV;
        if (info->init_error) {
                DBGERR(("%s init error=%d\n", info->device_name, info->init_error));
                return -ENODEV;
        }

        tty->driver_data = info;
        info->port.tty = tty;

        DBGINFO(("%s open, old ref count = %d\n", info->device_name, info->port.count));

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

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

        if (info->port.count == 1) {
                /* 1st open on this device, init hardware */
                retval = startup(info);
                if (retval < 0) {
                        mutex_unlock(&info->port.mutex);
                        goto cleanup;
                }
        }
        mutex_unlock(&info->port.mutex);
        retval = block_til_ready(tty, filp, info);
        if (retval) {
                DBGINFO(("%s block_til_ready rc=%d\n", info->device_name, retval));
                goto cleanup;
        }

        retval = 0;

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

        DBGINFO(("%s open rc=%d\n", info->device_name, retval));
        return retval;
}

static void close(struct tty_struct *tty, struct file *filp)
{
        struct slgt_info *info = tty->driver_data;

        if (sanity_check(info, tty->name, "close"))
                return;
        DBGINFO(("%s close entry, count=%d\n", info->device_name, info->port.count));

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

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

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

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

static void hangup(struct tty_struct *tty)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;

        if (sanity_check(info, tty->name, "hangup"))
                return;
        DBGINFO(("%s hangup\n", info->device_name));

        flush_buffer(tty);

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

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

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

static void set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;

        DBGINFO(("%s set_termios\n", tty->driver->name));

        change_params(info);

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

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

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

static void update_tx_timer(struct slgt_info *info)
{
        /*
         * use worst case speed of 1200bps to calculate transmit timeout
         * based on data in buffers (tbuf_bytes) and FIFO (128 bytes)
         */
        if (info->params.mode == MGSL_MODE_HDLC) {
                int timeout  = (tbuf_bytes(info) * 7) + 1000;
                mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(timeout));
        }
}

static int write(struct tty_struct *tty,
                 const unsigned char *buf, int count)
{
        int ret = 0;
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;

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

        DBGINFO(("%s write count=%d\n", info->device_name, count));

        if (!info->tx_buf || (count > info->max_frame_size))
                return -EIO;

        if (!count || tty->stopped || tty->hw_stopped)
                return 0;

        spin_lock_irqsave(&info->lock, flags);

        if (info->tx_count) {
                /* send accumulated data from send_char() */
                if (!tx_load(info, info->tx_buf, info->tx_count))
                        goto cleanup;
                info->tx_count = 0;
        }

        if (tx_load(info, buf, count))
                ret = count;

cleanup:
        spin_unlock_irqrestore(&info->lock, flags);
        DBGINFO(("%s write rc=%d\n", info->device_name, ret));
        return ret;
}

static int put_char(struct tty_struct *tty, unsigned char ch)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;
        int ret = 0;

        if (sanity_check(info, tty->name, "put_char"))
                return 0;
        DBGINFO(("%s put_char(%d)\n", info->device_name, ch));
        if (!info->tx_buf)
                return 0;
        spin_lock_irqsave(&info->lock,flags);
        if (info->tx_count < info->max_frame_size) {
                info->tx_buf[info->tx_count++] = ch;
                ret = 1;
        }
        spin_unlock_irqrestore(&info->lock,flags);
        return ret;
}

static void send_xchar(struct tty_struct *tty, char ch)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;

        if (sanity_check(info, tty->name, "send_xchar"))
                return;
        DBGINFO(("%s send_xchar(%d)\n", info->device_name, ch));
        info->x_char = ch;
        if (ch) {
                spin_lock_irqsave(&info->lock,flags);
                if (!info->tx_enabled)
                        tx_start(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }
}

static void wait_until_sent(struct tty_struct *tty, int timeout)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long orig_jiffies, char_time;

        if (!info )
                return;
        if (sanity_check(info, tty->name, "wait_until_sent"))
                return;
        DBGINFO(("%s wait_until_sent entry\n", info->device_name));
        if (!(info->port.flags & ASYNC_INITIALIZED))
                goto exit;

        orig_jiffies = jiffies;

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

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

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

        while (info->tx_active) {
                msleep_interruptible(jiffies_to_msecs(char_time));
                if (signal_pending(current))
                        break;
                if (timeout && time_after(jiffies, orig_jiffies + timeout))
                        break;
        }
exit:
        DBGINFO(("%s wait_until_sent exit\n", info->device_name));
}

static int write_room(struct tty_struct *tty)
{
        struct slgt_info *info = tty->driver_data;
        int ret;

        if (sanity_check(info, tty->name, "write_room"))
                return 0;
        ret = (info->tx_active) ? 0 : HDLC_MAX_FRAME_SIZE;
        DBGINFO(("%s write_room=%d\n", info->device_name, ret));
        return ret;
}

static void flush_chars(struct tty_struct *tty)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;

        if (sanity_check(info, tty->name, "flush_chars"))
                return;
        DBGINFO(("%s flush_chars entry tx_count=%d\n", info->device_name, info->tx_count));

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

        DBGINFO(("%s flush_chars start transmit\n", info->device_name));

        spin_lock_irqsave(&info->lock,flags);
        if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
                info->tx_count = 0;
        spin_unlock_irqrestore(&info->lock,flags);
}

static void flush_buffer(struct tty_struct *tty)
{
        struct slgt_info *info = tty->driver_data;
        unsigned long flags;

        if (sanity_check(info, tty->name, "flush_buffer"))
                return;
        DBGINFO(("%s flush_buffer\n", info->device_name));

        spin_lock_irqsave(&info->lock, flags);
        info->tx_count = 0;
        spin_unlock_irqrestore(&info->lock, flags);

        tty_wakeup(tty);
}

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

        if (sanity_check(info, tty->name, "tx_hold"))
                return;
        DBGINFO(("%s tx_hold\n", info->device_name));
        spin_lock_irqsave(&info->lock,flags);
        if (info->tx_enabled && info->params.mode == MGSL_MODE_ASYNC)
                tx_stop(info);
        spin_unlock_irqrestore(&info->lock,flags);
}

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

        if (sanity_check(info, tty->name, "tx_release"))
                return;
        DBGINFO(("%s tx_release\n", info->device_name));
        spin_lock_irqsave(&info->lock, flags);
        if (info->tx_count && tx_load(info, info->tx_buf, info->tx_count))
                info->tx_count = 0;
        spin_unlock_irqrestore(&info->lock, flags);
}

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

        if (sanity_check(info, tty->name, "ioctl"))
                return -ENODEV;
        DBGINFO(("%s ioctl() cmd=%08X\n", info->device_name, cmd));

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

        switch (cmd) {
        case MGSL_IOCWAITEVENT:
                return wait_mgsl_event(info, argp);
        case TIOCMIWAIT:
                return modem_input_wait(info,(int)arg);
        case MGSL_IOCSGPIO:
                return set_gpio(info, argp);
        case MGSL_IOCGGPIO:
                return get_gpio(info, argp);
        case MGSL_IOCWAITGPIO:
                return wait_gpio(info, argp);
        case MGSL_IOCGXSYNC:
                return get_xsync(info, argp);
        case MGSL_IOCSXSYNC:
                return set_xsync(info, (int)arg);
        case MGSL_IOCGXCTRL:
                return get_xctrl(info, argp);
        case MGSL_IOCSXCTRL:
                return set_xctrl(info, (int)arg);
        }
        mutex_lock(&info->port.mutex);
        switch (cmd) {
        case MGSL_IOCGPARAMS:
                ret = get_params(info, argp);
                break;
        case MGSL_IOCSPARAMS:
                ret = set_params(info, argp);
                break;
        case MGSL_IOCGTXIDLE:
                ret = get_txidle(info, argp);
                break;
        case MGSL_IOCSTXIDLE:
                ret = set_txidle(info, (int)arg);
                break;
        case MGSL_IOCTXENABLE:
                ret = tx_enable(info, (int)arg);
                break;
        case MGSL_IOCRXENABLE:
                ret = rx_enable(info, (int)arg);
                break;
        case MGSL_IOCTXABORT:
                ret = tx_abort(info);
                break;
        case MGSL_IOCGSTATS:
                ret = get_stats(info, argp);
                break;
        case MGSL_IOCGIF:
                ret = get_interface(info, argp);
                break;
        case MGSL_IOCSIF:
                ret = set_interface(info,(int)arg);
                break;
        default:
                ret = -ENOIOCTLCMD;
        }
        mutex_unlock(&info->port.mutex);
        return ret;
}

static int get_icount(struct tty_struct *tty,
                                struct serial_icounter_struct *icount)

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

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

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

        return 0;
}

/*
 * support for 32 bit ioctl calls on 64 bit systems
 */
#ifdef CONFIG_COMPAT
static long get_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *user_params)
{
        struct MGSL_PARAMS32 tmp_params;

        DBGINFO(("%s get_params32\n", info->device_name));
        memset(&tmp_params, 0, sizeof(tmp_params));
        tmp_params.mode            = (compat_ulong_t)info->params.mode;
        tmp_params.loopback        = info->params.loopback;
        tmp_params.flags           = info->params.flags;
        tmp_params.encoding        = info->params.encoding;
        tmp_params.clock_speed     = (compat_ulong_t)info->params.clock_speed;
        tmp_params.addr_filter     = info->params.addr_filter;
        tmp_params.crc_type        = info->params.crc_type;
        tmp_params.preamble_length = info->params.preamble_length;
        tmp_params.preamble        = info->params.preamble;
        tmp_params.data_rate       = (compat_ulong_t)info->params.data_rate;
        tmp_params.data_bits       = info->params.data_bits;
        tmp_params.stop_bits       = info->params.stop_bits;
        tmp_params.parity          = info->params.parity;
        if (copy_to_user(user_params, &tmp_params, sizeof(struct MGSL_PARAMS32)))
                return -EFAULT;
        return 0;
}

static long set_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *new_params)
{
        struct MGSL_PARAMS32 tmp_params;

        DBGINFO(("%s set_params32\n", info->device_name));
        if (copy_from_user(&tmp_params, new_params, sizeof(struct MGSL_PARAMS32)))
                return -EFAULT;

        spin_lock(&info->lock);
        if (tmp_params.mode == MGSL_MODE_BASE_CLOCK) {
                info->base_clock = tmp_params.clock_speed;
        } else {
                info->params.mode            = tmp_params.mode;
                info->params.loopback        = tmp_params.loopback;
                info->params.flags           = tmp_params.flags;
                info->params.encoding        = tmp_params.encoding;
                info->params.clock_speed     = tmp_params.clock_speed;
                info->params.addr_filter     = tmp_params.addr_filter;
                info->params.crc_type        = tmp_params.crc_type;
                info->params.preamble_length = tmp_params.preamble_length;
                info->params.preamble        = tmp_params.preamble;
                info->params.data_rate       = tmp_params.data_rate;
                info->params.data_bits       = tmp_params.data_bits;
                info->params.stop_bits       = tmp_params.stop_bits;
                info->params.parity          = tmp_params.parity;
        }
        spin_unlock(&info->lock);

        program_hw(info);

        return 0;
}

static long slgt_compat_ioctl(struct tty_struct *tty,
                         unsigned int cmd, unsigned long arg)
{
        struct slgt_info *info = tty->driver_data;
        int rc = -ENOIOCTLCMD;

        if (sanity_check(info, tty->name, "compat_ioctl"))
                return -ENODEV;
        DBGINFO(("%s compat_ioctl() cmd=%08X\n", info->device_name, cmd));

        switch (cmd) {

        case MGSL_IOCSPARAMS32:
                rc = set_params32(info, compat_ptr(arg));
                break;

        case MGSL_IOCGPARAMS32:
                rc = get_params32(info, compat_ptr(arg));
                break;

        case MGSL_IOCGPARAMS:
        case MGSL_IOCSPARAMS:
        case MGSL_IOCGTXIDLE:
        case MGSL_IOCGSTATS:
        case MGSL_IOCWAITEVENT:
        case MGSL_IOCGIF:
        case MGSL_IOCSGPIO:
        case MGSL_IOCGGPIO:
        case MGSL_IOCWAITGPIO:
        case MGSL_IOCGXSYNC:
        case MGSL_IOCGXCTRL:
        case MGSL_IOCSTXIDLE:
        case MGSL_IOCTXENABLE:
        case MGSL_IOCRXENABLE:
        case MGSL_IOCTXABORT:
        case TIOCMIWAIT:
        case MGSL_IOCSIF:
        case MGSL_IOCSXSYNC:
        case MGSL_IOCSXCTRL:
                rc = ioctl(tty, cmd, arg);
                break;
        }

        DBGINFO(("%s compat_ioctl() cmd=%08X rc=%d\n", info->device_name, cmd, rc));
        return rc;
}
#else
#define slgt_compat_ioctl NULL
#endif /* ifdef CONFIG_COMPAT */

/*
 * proc fs support
 */
static inline void line_info(struct seq_file *m, struct slgt_info *info)
{
        char stat_buf[30];
        unsigned long flags;

        seq_printf(m, "%s: IO=%08X IRQ=%d MaxFrameSize=%u\n",
                      info->device_name, info->phys_reg_addr,
                      info->irq_level, info->max_frame_size);

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

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

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

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

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

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

        seq_puts(m, "synclink_gt driver\n");

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

static int synclink_gt_proc_open(struct inode *inode, struct file *file)
{
        return single_open(file, synclink_gt_proc_show, NULL);
}

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

/*
 * return count of bytes in transmit buffer
 */
static int chars_in_buffer(struct tty_struct *tty)
{
        struct slgt_info *info = tty->driver_data;
        int count;
        if (sanity_check(info, tty->name, "chars_in_buffer"))
                return 0;
        count = tbuf_bytes(info);
        DBGINFO(("%s chars_in_buffer()=%d\n", info->device_name, count));
        return count;
}

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

        if (sanity_check(info, tty->name, "throttle"))
                return;
        DBGINFO(("%s throttle\n", info->device_name));
        if (I_IXOFF(tty))
                send_xchar(tty, STOP_CHAR(tty));
        if (C_CRTSCTS(tty)) {
                spin_lock_irqsave(&info->lock,flags);
                info->signals &= ~SerialSignal_RTS;
                set_signals(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }
}

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

        if (sanity_check(info, tty->name, "unthrottle"))
                return;
        DBGINFO(("%s unthrottle\n", info->device_name));
        if (I_IXOFF(tty)) {
                if (info->x_char)
                        info->x_char = 0;
                else
                        send_xchar(tty, START_CHAR(tty));
        }
        if (C_CRTSCTS(tty)) {
                spin_lock_irqsave(&info->lock,flags);
                info->signals |= SerialSignal_RTS;
                set_signals(info);
                spin_unlock_irqrestore(&info->lock,flags);
        }
}

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

        if (sanity_check(info, tty->name, "set_break"))
                return -EINVAL;
        DBGINFO(("%s set_break(%d)\n", info->device_name, break_state));

        spin_lock_irqsave(&info->lock,flags);
        value = rd_reg16(info, TCR);
        if (break_state == -1)
                value |= BIT6;
        else
                value &= ~BIT6;
        wr_reg16(info, TCR, value);
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

#if SYNCLINK_GENERIC_HDLC

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

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

        DBGINFO(("%s hdlcdev_attach\n", info->device_name));

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

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

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

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

        return 0;
}

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

        DBGINFO(("%s hdlc_xmit\n", dev->name));

        if (!skb->len)
                return NETDEV_TX_OK;

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

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

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

        spin_lock_irqsave(&info->lock, flags);
        tx_load(info, skb->data, skb->len);
        spin_unlock_irqrestore(&info->lock, flags);

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

        return NETDEV_TX_OK;
}

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

        if (!try_module_get(THIS_MODULE))
                return -EBUSY;

        DBGINFO(("%s hdlcdev_open\n", dev->name));

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

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

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

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

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

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

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

        DBGINFO(("%s hdlcdev_close\n", dev->name));

        netif_stop_queue(dev);

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

        hdlc_close(dev);

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

        module_put(THIS_MODULE);
        return 0;
}

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

        DBGINFO(("%s hdlcdev_ioctl\n", dev->name));

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

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

        memset(&new_line, 0, sizeof(new_line));

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

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

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

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

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

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

        case IF_IFACE_SYNC_SERIAL: /* set sync_serial_settings */

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

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

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

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

                info->params.loopback = new_line.loopback;

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

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

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

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

        DBGINFO(("%s hdlcdev_tx_timeout\n", dev->name));

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

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

        netif_wake_queue(dev);
}

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

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

        DBGINFO(("%s hdlcdev_rx\n", dev->name));

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

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

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

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

        netif_rx(skb);
}

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

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

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

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

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

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

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

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

        info->netdev = dev;
        return 0;
}

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

#endif /* ifdef CONFIG_HDLC */

/*
 * get async data from rx DMA buffers
 */
static void rx_async(struct slgt_info *info)
{
        struct mgsl_icount *icount = &info->icount;
        unsigned int start, end;
        unsigned char *p;
        unsigned char status;
        struct slgt_desc *bufs = info->rbufs;
        int i, count;
        int chars = 0;
        int stat;
        unsigned char ch;

        start = end = info->rbuf_current;

        while(desc_complete(bufs[end])) {
                count = desc_count(bufs[end]) - info->rbuf_index;
                p     = bufs[end].buf + info->rbuf_index;

                DBGISR(("%s rx_async count=%d\n", info->device_name, count));
                DBGDATA(info, p, count, "rx");

                for(i=0 ; i < count; i+=2, p+=2) {
                        ch = *p;
                        icount->rx++;

                        stat = 0;

                        status = *(p + 1) & (BIT1 + BIT0);
                        if (status) {
                                if (status & BIT1)
                                        icount->parity++;
                                else if (status & BIT0)
                                        icount->frame++;
                                /* discard char if tty control flags say so */
                                if (status & info->ignore_status_mask)
                                        continue;
                                if (status & BIT1)
                                        stat = TTY_PARITY;
                                else if (status & BIT0)
                                        stat = TTY_FRAME;
                        }
                        tty_insert_flip_char(&info->port, ch, stat);
                        chars++;
                }

                if (i < count) {
                        /* receive buffer not completed */
                        info->rbuf_index += i;
                        mod_timer(&info->rx_timer, jiffies + 1);
                        break;
                }

                info->rbuf_index = 0;
                free_rbufs(info, end, end);

                if (++end == info->rbuf_count)
                        end = 0;

                /* if entire list searched then no frame available */
                if (end == start)
                        break;
        }

        if (chars)
                tty_flip_buffer_push(&info->port);
}

/*
 * return next bottom half action to perform
 */
static int bh_action(struct slgt_info *info)
{
        unsigned long flags;
        int rc;

        spin_lock_irqsave(&info->lock,flags);

        if (info->pending_bh & BH_RECEIVE) {
                info->pending_bh &= ~BH_RECEIVE;
                rc = BH_RECEIVE;
        } else if (info->pending_bh & BH_TRANSMIT) {
                info->pending_bh &= ~BH_TRANSMIT;
                rc = BH_TRANSMIT;
        } else if (info->pending_bh & BH_STATUS) {
                info->pending_bh &= ~BH_STATUS;
                rc = BH_STATUS;
        } else {
                /* Mark BH routine as complete */
                info->bh_running = false;
                info->bh_requested = false;
                rc = 0;
        }

        spin_unlock_irqrestore(&info->lock,flags);

        return rc;
}

/*
 * perform bottom half processing
 */
static void bh_handler(struct work_struct *work)
{
        struct slgt_info *info = container_of(work, struct slgt_info, task);
        int action;

        info->bh_running = true;

        while((action = bh_action(info))) {
                switch (action) {
                case BH_RECEIVE:
                        DBGBH(("%s bh receive\n", info->device_name));
                        switch(info->params.mode) {
                        case MGSL_MODE_ASYNC:
                                rx_async(info);
                                break;
                        case MGSL_MODE_HDLC:
                                while(rx_get_frame(info));
                                break;
                        case MGSL_MODE_RAW:
                        case MGSL_MODE_MONOSYNC:
                        case MGSL_MODE_BISYNC:
                        case MGSL_MODE_XSYNC:
                                while(rx_get_buf(info));
                                break;
                        }
                        /* restart receiver if rx DMA buffers exhausted */
                        if (info->rx_restart)
                                rx_start(info);
                        break;
                case BH_TRANSMIT:
                        bh_transmit(info);
                        break;
                case BH_STATUS:
                        DBGBH(("%s bh status\n", info->device_name));
                        info->ri_chkcount = 0;
                        info->dsr_chkcount = 0;
                        info->dcd_chkcount = 0;
                        info->cts_chkcount = 0;
                        break;
                default:
                        DBGBH(("%s unknown action\n", info->device_name));
                        break;
                }
        }
        DBGBH(("%s bh_handler exit\n", info->device_name));
}

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

        DBGBH(("%s bh_transmit\n", info->device_name));
        if (tty)
                tty_wakeup(tty);
}

static void dsr_change(struct slgt_info *info, unsigned short status)
{
        if (status & BIT3) {
                info->signals |= SerialSignal_DSR;
                info->input_signal_events.dsr_up++;
        } else {
                info->signals &= ~SerialSignal_DSR;
                info->input_signal_events.dsr_down++;
        }
        DBGISR(("dsr_change %s signals=%04X\n", info->device_name, info->signals));
        if ((info->dsr_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
                slgt_irq_off(info, IRQ_DSR);
                return;
        }
        info->icount.dsr++;
        wake_up_interruptible(&info->status_event_wait_q);
        wake_up_interruptible(&info->event_wait_q);
        info->pending_bh |= BH_STATUS;
}

static void cts_change(struct slgt_info *info, unsigned short status)
{
        if (status & BIT2) {
                info->signals |= SerialSignal_CTS;
                info->input_signal_events.cts_up++;
        } else {
                info->signals &= ~SerialSignal_CTS;
                info->input_signal_events.cts_down++;
        }
        DBGISR(("cts_change %s signals=%04X\n", info->device_name, info->signals));
        if ((info->cts_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
                slgt_irq_off(info, IRQ_CTS);
                return;
        }
        info->icount.cts++;
        wake_up_interruptible(&info->status_event_wait_q);
        wake_up_interruptible(&info->event_wait_q);
        info->pending_bh |= BH_STATUS;

        if (tty_port_cts_enabled(&info->port)) {
                if (info->port.tty) {
                        if (info->port.tty->hw_stopped) {
                                if (info->signals & SerialSignal_CTS) {
                                        info->port.tty->hw_stopped = 0;
                                        info->pending_bh |= BH_TRANSMIT;
                                        return;
                                }
                        } else {
                                if (!(info->signals & SerialSignal_CTS))
                                        info->port.tty->hw_stopped = 1;
                        }
                }
        }
}

static void dcd_change(struct slgt_info *info, unsigned short status)
{
        if (status & BIT1) {
                info->signals |= SerialSignal_DCD;
                info->input_signal_events.dcd_up++;
        } else {
                info->signals &= ~SerialSignal_DCD;
                info->input_signal_events.dcd_down++;
        }
        DBGISR(("dcd_change %s signals=%04X\n", info->device_name, info->signals));
        if ((info->dcd_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
                slgt_irq_off(info, IRQ_DCD);
                return;
        }
        info->icount.dcd++;
#if SYNCLINK_GENERIC_HDLC
        if (info->netcount) {
                if (info->signals & SerialSignal_DCD)
                        netif_carrier_on(info->netdev);
                else
                        netif_carrier_off(info->netdev);
        }
#endif
        wake_up_interruptible(&info->status_event_wait_q);
        wake_up_interruptible(&info->event_wait_q);
        info->pending_bh |= BH_STATUS;

        if (info->port.flags & ASYNC_CHECK_CD) {
                if (info->signals & SerialSignal_DCD)
                        wake_up_interruptible(&info->port.open_wait);
                else {
                        if (info->port.tty)
                                tty_hangup(info->port.tty);
                }
        }
}

static void ri_change(struct slgt_info *info, unsigned short status)
{
        if (status & BIT0) {
                info->signals |= SerialSignal_RI;
                info->input_signal_events.ri_up++;
        } else {
                info->signals &= ~SerialSignal_RI;
                info->input_signal_events.ri_down++;
        }
        DBGISR(("ri_change %s signals=%04X\n", info->device_name, info->signals));
        if ((info->ri_chkcount)++ == IO_PIN_SHUTDOWN_LIMIT) {
                slgt_irq_off(info, IRQ_RI);
                return;
        }
        info->icount.rng++;
        wake_up_interruptible(&info->status_event_wait_q);
        wake_up_interruptible(&info->event_wait_q);
        info->pending_bh |= BH_STATUS;
}

static void isr_rxdata(struct slgt_info *info)
{
        unsigned int count = info->rbuf_fill_count;
        unsigned int i = info->rbuf_fill_index;
        unsigned short reg;

        while (rd_reg16(info, SSR) & IRQ_RXDATA) {
                reg = rd_reg16(info, RDR);
                DBGISR(("isr_rxdata %s RDR=%04X\n", info->device_name, reg));
                if (desc_complete(info->rbufs[i])) {
                        /* all buffers full */
                        rx_stop(info);
                        info->rx_restart = 1;
                        continue;
                }
                info->rbufs[i].buf[count++] = (unsigned char)reg;
                /* async mode saves status byte to buffer for each data byte */
                if (info->params.mode == MGSL_MODE_ASYNC)
                        info->rbufs[i].buf[count++] = (unsigned char)(reg >> 8);
                if (count == info->rbuf_fill_level || (reg & BIT10)) {
                        /* buffer full or end of frame */
                        set_desc_count(info->rbufs[i], count);
                        set_desc_status(info->rbufs[i], BIT15 | (reg >> 8));
                        info->rbuf_fill_count = count = 0;
                        if (++i == info->rbuf_count)
                                i = 0;
                        info->pending_bh |= BH_RECEIVE;
                }
        }

        info->rbuf_fill_index = i;
        info->rbuf_fill_count = count;
}

static void isr_serial(struct slgt_info *info)
{
        unsigned short status = rd_reg16(info, SSR);

        DBGISR(("%s isr_serial status=%04X\n", info->device_name, status));

        wr_reg16(info, SSR, status); /* clear pending */

        info->irq_occurred = true;

        if (info->params.mode == MGSL_MODE_ASYNC) {
                if (status & IRQ_TXIDLE) {
                        if (info->tx_active)
                                isr_txeom(info, status);
                }
                if (info->rx_pio && (status & IRQ_RXDATA))
                        isr_rxdata(info);
                if ((status & IRQ_RXBREAK) && (status & RXBREAK)) {
                        info->icount.brk++;
                        /* process break detection if tty control allows */
                        if (info->port.tty) {
                                if (!(status & info->ignore_status_mask)) {
                                        if (info->read_status_mask & MASK_BREAK) {
                                                tty_insert_flip_char(&info->port, 0, TTY_BREAK);
                                                if (info->port.flags & ASYNC_SAK)
                                                        do_SAK(info->port.tty);
                                        }
                                }
                        }
                }
        } else {
                if (status & (IRQ_TXIDLE + IRQ_TXUNDER))
                        isr_txeom(info, status);
                if (info->rx_pio && (status & IRQ_RXDATA))
                        isr_rxdata(info);
                if (status & IRQ_RXIDLE) {
                        if (status & RXIDLE)
                                info->icount.rxidle++;
                        else
                                info->icount.exithunt++;
                        wake_up_interruptible(&info->event_wait_q);
                }

                if (status & IRQ_RXOVER)
                        rx_start(info);
        }

        if (status & IRQ_DSR)
                dsr_change(info, status);
        if (status & IRQ_CTS)
                cts_change(info, status);
        if (status & IRQ_DCD)
                dcd_change(info, status);
        if (status & IRQ_RI)
                ri_change(info, status);
}

static void isr_rdma(struct slgt_info *info)
{
        unsigned int status = rd_reg32(info, RDCSR);

        DBGISR(("%s isr_rdma status=%08x\n", info->device_name, status));

        /* RDCSR (rx DMA control/status)
         *
         * 31..07  reserved
         * 06      save status byte to DMA buffer
         * 05      error
         * 04      eol (end of list)
         * 03      eob (end of buffer)
         * 02      IRQ enable
         * 01      reset
         * 00      enable
         */
        wr_reg32(info, RDCSR, status);  /* clear pending */

        if (status & (BIT5 + BIT4)) {
                DBGISR(("%s isr_rdma rx_restart=1\n", info->device_name));
                info->rx_restart = true;
        }
        info->pending_bh |= BH_RECEIVE;
}

static void isr_tdma(struct slgt_info *info)
{
        unsigned int status = rd_reg32(info, TDCSR);

        DBGISR(("%s isr_tdma status=%08x\n", info->device_name, status));

        /* TDCSR (tx DMA control/status)
         *
         * 31..06  reserved
         * 05      error
         * 04      eol (end of list)
         * 03      eob (end of buffer)
         * 02      IRQ enable
         * 01      reset
         * 00      enable
         */
        wr_reg32(info, TDCSR, status);  /* clear pending */

        if (status & (BIT5 + BIT4 + BIT3)) {
                // another transmit buffer has completed
                // run bottom half to get more send data from user
                info->pending_bh |= BH_TRANSMIT;
        }
}

/*
 * return true if there are unsent tx DMA buffers, otherwise false
 *
 * if there are unsent buffers then info->tbuf_start
 * is set to index of first unsent buffer
 */
static bool unsent_tbufs(struct slgt_info *info)
{
        unsigned int i = info->tbuf_current;
        bool rc = false;

        /*
         * search backwards from last loaded buffer (precedes tbuf_current)
         * for first unsent buffer (desc_count > 0)
         */

        do {
                if (i)
                        i--;
                else
                        i = info->tbuf_count - 1;
                if (!desc_count(info->tbufs[i]))
                        break;
                info->tbuf_start = i;
                rc = true;
        } while (i != info->tbuf_current);

        return rc;
}

static void isr_txeom(struct slgt_info *info, unsigned short status)
{
        DBGISR(("%s txeom status=%04x\n", info->device_name, status));

        slgt_irq_off(info, IRQ_TXDATA + IRQ_TXIDLE + IRQ_TXUNDER);
        tdma_reset(info);
        if (status & IRQ_TXUNDER) {
                unsigned short val = rd_reg16(info, TCR);
                wr_reg16(info, TCR, (unsigned short)(val | BIT2)); /* set reset bit */
                wr_reg16(info, TCR, val); /* clear reset bit */
        }

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

                if (unsent_tbufs(info)) {
                        tx_start(info);
                        update_tx_timer(info);
                        return;
                }
                info->tx_active = false;

                del_timer(&info->tx_timer);

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

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

static void isr_gpio(struct slgt_info *info, unsigned int changed, unsigned int state)
{
        struct cond_wait *w, *prev;

        /* wake processes waiting for specific transitions */
        for (w = info->gpio_wait_q, prev = NULL ; w != NULL ; w = w->next) {
                if (w->data & changed) {
                        w->data = state;
                        wake_up_interruptible(&w->q);
                        if (prev != NULL)
                                prev->next = w->next;
                        else
                                info->gpio_wait_q = w->next;
                } else
                        prev = w;
        }
}

/* interrupt service routine
 *
 *      irq     interrupt number
 *      dev_id  device ID supplied during interrupt registration
 */
static irqreturn_t slgt_interrupt(int dummy, void *dev_id)
{
        struct slgt_info *info = dev_id;
        unsigned int gsr;
        unsigned int i;

        DBGISR(("slgt_interrupt irq=%d entry\n", info->irq_level));

        while((gsr = rd_reg32(info, GSR) & 0xffffff00)) {
                DBGISR(("%s gsr=%08x\n", info->device_name, gsr));
                info->irq_occurred = true;
                for(i=0; i < info->port_count ; i++) {
                        if (info->port_array[i] == NULL)
                                continue;
                        spin_lock(&info->port_array[i]->lock);
                        if (gsr & (BIT8 << i))
                                isr_serial(info->port_array[i]);
                        if (gsr & (BIT16 << (i*2)))
                                isr_rdma(info->port_array[i]);
                        if (gsr & (BIT17 << (i*2)))
                                isr_tdma(info->port_array[i]);
                        spin_unlock(&info->port_array[i]->lock);
                }
        }

        if (info->gpio_present) {
                unsigned int state;
                unsigned int changed;
                spin_lock(&info->lock);
                while ((changed = rd_reg32(info, IOSR)) != 0) {
                        DBGISR(("%s iosr=%08x\n", info->device_name, changed));
                        /* read latched state of GPIO signals */
                        state = rd_reg32(info, IOVR);
                        /* clear pending GPIO interrupt bits */
                        wr_reg32(info, IOSR, changed);
                        for (i=0 ; i < info->port_count ; i++) {
                                if (info->port_array[i] != NULL)
                                        isr_gpio(info->port_array[i], changed, state);
                        }
                }
                spin_unlock(&info->lock);
        }

        for(i=0; i < info->port_count ; i++) {
                struct slgt_info *port = info->port_array[i];
                if (port == NULL)
                        continue;
                spin_lock(&port->lock);
                if ((port->port.count || port->netcount) &&
                    port->pending_bh && !port->bh_running &&
                    !port->bh_requested) {
                        DBGISR(("%s bh queued\n", port->device_name));
                        schedule_work(&port->task);
                        port->bh_requested = true;
                }
                spin_unlock(&port->lock);
        }

        DBGISR(("slgt_interrupt irq=%d exit\n", info->irq_level));
        return IRQ_HANDLED;
}

static int startup(struct slgt_info *info)
{
        DBGINFO(("%s startup\n", info->device_name));

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

        if (!info->tx_buf) {
                info->tx_buf = kmalloc(info->max_frame_size, GFP_KERNEL);
                if (!info->tx_buf) {
                        DBGERR(("%s can't allocate tx buffer\n", info->device_name));
                        return -ENOMEM;
                }
        }

        info->pending_bh = 0;

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

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

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

        info->port.flags |= ASYNC_INITIALIZED;

        return 0;
}

/*
 *  called by close() and hangup() to shutdown hardware
 */
static void shutdown(struct slgt_info *info)
{
        unsigned long flags;

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

        DBGINFO(("%s shutdown\n", 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);
        del_timer_sync(&info->rx_timer);

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

        spin_lock_irqsave(&info->lock,flags);

        tx_stop(info);
        rx_stop(info);

        slgt_irq_off(info, IRQ_ALL | IRQ_MASTER);

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

        flush_cond_wait(&info->gpio_wait_q);

        spin_unlock_irqrestore(&info->lock,flags);

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

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

static void program_hw(struct slgt_info *info)
{
        unsigned long flags;

        spin_lock_irqsave(&info->lock,flags);

        rx_stop(info);
        tx_stop(info);

        if (info->params.mode != MGSL_MODE_ASYNC ||
            info->netcount)
                sync_mode(info);
        else
                async_mode(info);

        set_signals(info);

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

        slgt_irq_on(info, IRQ_DCD | IRQ_CTS | IRQ_DSR | IRQ_RI);
        get_signals(info);

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

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

/*
 * reconfigure adapter based on new parameters
 */
static void change_params(struct slgt_info *info)
{
        unsigned cflag;
        int bits_per_char;

        if (!info->port.tty)
                return;
        DBGINFO(("%s change_params\n", 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->signals |= SerialSignal_RTS | SerialSignal_DTR;
        else
                info->signals &= ~(SerialSignal_RTS | SerialSignal_DTR);

        /* byte size and parity */

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

        info->params.stop_bits = (cflag & CSTOPB) ? 2 : 1;

        if (cflag & PARENB)
                info->params.parity = (cflag & PARODD) ? ASYNC_PARITY_ODD : ASYNC_PARITY_EVEN;
        else
                info->params.parity = ASYNC_PARITY_NONE;

        /* 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;

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

        if (info->params.data_rate) {
                info->timeout = (32*HZ*bits_per_char) /
                                info->params.data_rate;
        }
        info->timeout += HZ/50;         /* Add .02 seconds of slop */

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

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

        /* process tty input control flags */

        info->read_status_mask = IRQ_RXOVER;
        if (I_INPCK(info->port.tty))
                info->read_status_mask |= MASK_PARITY | MASK_FRAMING;
        if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
                info->read_status_mask |= MASK_BREAK;
        if (I_IGNPAR(info->port.tty))
                info->ignore_status_mask |= MASK_PARITY | MASK_FRAMING;
        if (I_IGNBRK(info->port.tty)) {
                info->ignore_status_mask |= MASK_BREAK;
                /* If ignoring parity and break indicators, ignore
                 * overruns too.  (For real raw support).
                 */
                if (I_IGNPAR(info->port.tty))
                        info->ignore_status_mask |= MASK_OVERRUN;
        }

        program_hw(info);
}

static int get_stats(struct slgt_info *info, struct mgsl_icount __user *user_icount)
{
        DBGINFO(("%s get_stats\n",  info->device_name));
        if (!user_icount) {
                memset(&info->icount, 0, sizeof(info->icount));
        } else {
                if (copy_to_user(user_icount, &info->icount, sizeof(struct mgsl_icount)))
                        return -EFAULT;
        }
        return 0;
}

static int get_params(struct slgt_info *info, MGSL_PARAMS __user *user_params)
{
        DBGINFO(("%s get_params\n", info->device_name));
        if (copy_to_user(user_params, &info->params, sizeof(MGSL_PARAMS)))
                return -EFAULT;
        return 0;
}

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

        DBGINFO(("%s set_params\n", info->device_name));
        if (copy_from_user(&tmp_params, new_params, sizeof(MGSL_PARAMS)))
                return -EFAULT;

        spin_lock_irqsave(&info->lock, flags);
        if (tmp_params.mode == MGSL_MODE_BASE_CLOCK)
                info->base_clock = tmp_params.clock_speed;
        else
                memcpy(&info->params, &tmp_params, sizeof(MGSL_PARAMS));
        spin_unlock_irqrestore(&info->lock, flags);

        program_hw(info);

        return 0;
}

static int get_txidle(struct slgt_info *info, int __user *idle_mode)
{
        DBGINFO(("%s get_txidle=%d\n", info->device_name, info->idle_mode));
        if (put_user(info->idle_mode, idle_mode))
                return -EFAULT;
        return 0;
}

static int set_txidle(struct slgt_info *info, int idle_mode)
{
        unsigned long flags;
        DBGINFO(("%s set_txidle(%d)\n", info->device_name, idle_mode));
        spin_lock_irqsave(&info->lock,flags);
        info->idle_mode = idle_mode;
        if (info->params.mode != MGSL_MODE_ASYNC)
                tx_set_idle(info);
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

static int tx_enable(struct slgt_info *info, int enable)
{
        unsigned long flags;
        DBGINFO(("%s tx_enable(%d)\n", info->device_name, enable));
        spin_lock_irqsave(&info->lock,flags);
        if (enable) {
                if (!info->tx_enabled)
                        tx_start(info);
        } else {
                if (info->tx_enabled)
                        tx_stop(info);
        }
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

/*
 * abort transmit HDLC frame
 */
static int tx_abort(struct slgt_info *info)
{
        unsigned long flags;
        DBGINFO(("%s tx_abort\n", info->device_name));
        spin_lock_irqsave(&info->lock,flags);
        tdma_reset(info);
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

static int rx_enable(struct slgt_info *info, int enable)
{
        unsigned long flags;
        unsigned int rbuf_fill_level;
        DBGINFO(("%s rx_enable(%08x)\n", info->device_name, enable));
        spin_lock_irqsave(&info->lock,flags);
        /*
         * enable[31..16] = receive DMA buffer fill level
         * 0 = noop (leave fill level unchanged)
         * fill level must be multiple of 4 and <= buffer size
         */
        rbuf_fill_level = ((unsigned int)enable) >> 16;
        if (rbuf_fill_level) {
                if ((rbuf_fill_level > DMABUFSIZE) || (rbuf_fill_level % 4)) {
                        spin_unlock_irqrestore(&info->lock, flags);
                        return -EINVAL;
                }
                info->rbuf_fill_level = rbuf_fill_level;
                if (rbuf_fill_level < 128)
                        info->rx_pio = 1; /* PIO mode */
                else
                        info->rx_pio = 0; /* DMA mode */
                rx_stop(info); /* restart receiver to use new fill level */
        }

        /*
         * enable[1..0] = receiver enable command
         * 0 = disable
         * 1 = enable
         * 2 = enable or force hunt mode if already enabled
         */
        enable &= 3;
        if (enable) {
                if (!info->rx_enabled)
                        rx_start(info);
                else if (enable == 2) {
                        /* force hunt mode (write 1 to RCR[3]) */
                        wr_reg16(info, RCR, rd_reg16(info, RCR) | BIT3);
                }
        } else {
                if (info->rx_enabled)
                        rx_stop(info);
        }
        spin_unlock_irqrestore(&info->lock,flags);
        return 0;
}

/*
 *  wait for specified event to occur
 */
static int wait_mgsl_event(struct slgt_info *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);

        if (get_user(mask, mask_ptr))
                return -EFAULT;

        DBGINFO(("%s wait_mgsl_event(%d)\n", info->device_name, mask));

        spin_lock_irqsave(&info->lock,flags);

        /* return immediately if state matches requested events */
        get_signals(info);
        s = info->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->lock,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)) {
                unsigned short val = rd_reg16(info, SCR);
                if (!(val & IRQ_RXIDLE))
                        wr_reg16(info, SCR, (unsigned short)(val | IRQ_RXIDLE));
        }

        set_current_state(TASK_INTERRUPTIBLE);
        add_wait_queue(&info->event_wait_q, &wait);

        spin_unlock_irqrestore(&info->lock,flags);

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

                /* get current irq counts */
                spin_lock_irqsave(&info->lock,flags);
                cnow = info->icount;
                newsigs = info->input_signal_events;
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&info->lock,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->lock,flags);
                if (!waitqueue_active(&info->event_wait_q)) {
                        /* disable enable exit hunt mode/idle rcvd IRQs */
                        wr_reg16(info, SCR,
                                (unsigned short)(rd_reg16(info, SCR) & ~IRQ_RXIDLE));
                }
                spin_unlock_irqrestore(&info->lock,flags);
        }
exit:
        if (rc == 0)
                rc = put_user(events, mask_ptr);
        return rc;
}

static int get_interface(struct slgt_info *info, int __user *if_mode)
{
        DBGINFO(("%s get_interface=%x\n", info->device_name, info->if_mode));
        if (put_user(info->if_mode, if_mode))
                return -EFAULT;
        return 0;
}

static int set_interface(struct slgt_info *info, int if_mode)
{
        unsigned long flags;
        unsigned short val;

        DBGINFO(("%s set_interface=%x)\n", info->device_name, if_mode));
        spin_lock_irqsave(&info->lock,flags);
        info->if_mode = if_mode;

        msc_set_vcr(info);

        /* TCR (tx control) 07  1=RTS driver control */
        val = rd_reg16(info, TCR);
        if (info->if_mode & MGSL_INTERFACE_RTS_EN)
                val |= BIT7;
        else
                val &= ~BIT7;
        wr_reg16(info, TCR, val);

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

static int get_xsync(struct slgt_info *info, int __user *xsync)
{
        DBGINFO(("%s get_xsync=%x\n", info->device_name, info->xsync));
        if (put_user(info->xsync, xsync))
                return -EFAULT;
        return 0;
}

/*
 * set extended sync pattern (1 to 4 bytes) for extended sync mode
 *
 * sync pattern is contained in least significant bytes of value
 * most significant byte of sync pattern is oldest (1st sent/detected)
 */
static int set_xsync(struct slgt_info *info, int xsync)
{
        unsigned long flags;

        DBGINFO(("%s set_xsync=%x)\n", info->device_name, xsync));
        spin_lock_irqsave(&info->lock, flags);
        info->xsync = xsync;
        wr_reg32(info, XSR, xsync);
        spin_unlock_irqrestore(&info->lock, flags);
        return 0;
}

static int get_xctrl(struct slgt_info *info, int __user *xctrl)
{
        DBGINFO(("%s get_xctrl=%x\n", info->device_name, info->xctrl));
        if (put_user(info->xctrl, xctrl))
                return -EFAULT;
        return 0;
}

/*
 * set extended control options
 *
 * xctrl[31:19] reserved, must be zero
 * xctrl[18:17] extended sync pattern length in bytes
 *              00 = 1 byte  in xsr[7:0]
 *              01 = 2 bytes in xsr[15:0]
 *              10 = 3 bytes in xsr[23:0]
 *              11 = 4 bytes in xsr[31:0]
 * xctrl[16]    1 = enable terminal count, 0=disabled
 * xctrl[15:0]  receive terminal count for fixed length packets
 *              value is count minus one (0 = 1 byte packet)
 *              when terminal count is reached, receiver
 *              automatically returns to hunt mode and receive
 *              FIFO contents are flushed to DMA buffers with
 *              end of frame (EOF) status
 */
static int set_xctrl(struct slgt_info *info, int xctrl)
{
        unsigned long flags;

        DBGINFO(("%s set_xctrl=%x)\n", info->device_name, xctrl));
        spin_lock_irqsave(&info->lock, flags);
        info->xctrl = xctrl;
        wr_reg32(info, XCR, xctrl);
        spin_unlock_irqrestore(&info->lock, flags);
        return 0;
}

/*
 * set general purpose IO pin state and direction
 *
 * user_gpio fields:
 * state   each bit indicates a pin state
 * smask   set bit indicates pin state to set
 * dir     each bit indicates a pin direction (0=input, 1=output)
 * dmask   set bit indicates pin direction to set
 */
static int set_gpio(struct slgt_info *info, struct gpio_desc __user *user_gpio)
{
        unsigned long flags;
        struct gpio_desc gpio;
        __u32 data;

        if (!info->gpio_present)
                return -EINVAL;
        if (copy_from_user(&gpio, user_gpio, sizeof(gpio)))
                return -EFAULT;
        DBGINFO(("%s set_gpio state=%08x smask=%08x dir=%08x dmask=%08x\n",
                 info->device_name, gpio.state, gpio.smask,
                 gpio.dir, gpio.dmask));

        spin_lock_irqsave(&info->port_array[0]->lock, flags);
        if (gpio.dmask) {
                data = rd_reg32(info, IODR);
                data |= gpio.dmask & gpio.dir;
                data &= ~(gpio.dmask & ~gpio.dir);
                wr_reg32(info, IODR, data);
        }
        if (gpio.smask) {
                data = rd_reg32(info, IOVR);
                data |= gpio.smask & gpio.state;
                data &= ~(gpio.smask & ~gpio.state);
                wr_reg32(info, IOVR, data);
        }
        spin_unlock_irqrestore(&info->port_array[0]->lock, flags);

        return 0;
}

/*
 * get general purpose IO pin state and direction