Linux 4.4-rc8

[linux/fpc-iii.git] / net / irda / ircomm / ircomm_tty.c

/*********************************************************************
 *
 * Filename:      ircomm_tty.c
 * Version:       1.0
 * Description:   IrCOMM serial TTY driver
 * Status:        Experimental.
 * Author:        Dag Brattli <dagb@cs.uit.no>
 * Created at:    Sun Jun  6 21:00:56 1999
 * Modified at:   Wed Feb 23 00:09:02 2000
 * Modified by:   Dag Brattli <dagb@cs.uit.no>
 * Sources:       serial.c and previous IrCOMM work by Takahide Higuchi
 *
 *     Copyright (c) 1999-2000 Dag Brattli, All Rights Reserved.
 *     Copyright (c) 2000-2003 Jean Tourrilhes <jt@hpl.hp.com>
 *
 *     This program is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU General Public License as
 *     published by the Free Software Foundation; either version 2 of
 *     the License, or (at your option) any later version.
 *
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 ********************************************************************/

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/termios.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/interrupt.h>
#include <linux/device.h>               /* for MODULE_ALIAS_CHARDEV_MAJOR */

#include <asm/uaccess.h>

#include <net/irda/irda.h>
#include <net/irda/irmod.h>

#include <net/irda/ircomm_core.h>
#include <net/irda/ircomm_param.h>
#include <net/irda/ircomm_tty_attach.h>
#include <net/irda/ircomm_tty.h>

static int ircomm_tty_install(struct tty_driver *driver,
                struct tty_struct *tty);
static int  ircomm_tty_open(struct tty_struct *tty, struct file *filp);
static void ircomm_tty_close(struct tty_struct * tty, struct file *filp);
static int  ircomm_tty_write(struct tty_struct * tty,
                             const unsigned char *buf, int count);
static int  ircomm_tty_write_room(struct tty_struct *tty);
static void ircomm_tty_throttle(struct tty_struct *tty);
static void ircomm_tty_unthrottle(struct tty_struct *tty);
static int  ircomm_tty_chars_in_buffer(struct tty_struct *tty);
static void ircomm_tty_flush_buffer(struct tty_struct *tty);
static void ircomm_tty_send_xchar(struct tty_struct *tty, char ch);
static void ircomm_tty_wait_until_sent(struct tty_struct *tty, int timeout);
static void ircomm_tty_hangup(struct tty_struct *tty);
static void ircomm_tty_do_softint(struct work_struct *work);
static void ircomm_tty_shutdown(struct ircomm_tty_cb *self);
static void ircomm_tty_stop(struct tty_struct *tty);

static int ircomm_tty_data_indication(void *instance, void *sap,
                                      struct sk_buff *skb);
static int ircomm_tty_control_indication(void *instance, void *sap,
                                         struct sk_buff *skb);
static void ircomm_tty_flow_indication(void *instance, void *sap,
                                       LOCAL_FLOW cmd);
#ifdef CONFIG_PROC_FS
static const struct file_operations ircomm_tty_proc_fops;
#endif /* CONFIG_PROC_FS */
static struct tty_driver *driver;

static hashbin_t *ircomm_tty = NULL;

static const struct tty_operations ops = {
        .install         = ircomm_tty_install,
        .open            = ircomm_tty_open,
        .close           = ircomm_tty_close,
        .write           = ircomm_tty_write,
        .write_room      = ircomm_tty_write_room,
        .chars_in_buffer = ircomm_tty_chars_in_buffer,
        .flush_buffer    = ircomm_tty_flush_buffer,
        .ioctl           = ircomm_tty_ioctl,    /* ircomm_tty_ioctl.c */
        .tiocmget        = ircomm_tty_tiocmget, /* ircomm_tty_ioctl.c */
        .tiocmset        = ircomm_tty_tiocmset, /* ircomm_tty_ioctl.c */
        .throttle        = ircomm_tty_throttle,
        .unthrottle      = ircomm_tty_unthrottle,
        .send_xchar      = ircomm_tty_send_xchar,
        .set_termios     = ircomm_tty_set_termios,
        .stop            = ircomm_tty_stop,
        .start           = ircomm_tty_start,
        .hangup          = ircomm_tty_hangup,
        .wait_until_sent = ircomm_tty_wait_until_sent,
#ifdef CONFIG_PROC_FS
        .proc_fops       = &ircomm_tty_proc_fops,
#endif /* CONFIG_PROC_FS */
};

static void ircomm_port_raise_dtr_rts(struct tty_port *port, int raise)
{
        struct ircomm_tty_cb *self = container_of(port, struct ircomm_tty_cb,
                        port);
        /*
         * Here, we use to lock those two guys, but as ircomm_param_request()
         * does it itself, I don't see the point (and I see the deadlock).
         * Jean II
         */
        if (raise)
                self->settings.dte |= IRCOMM_RTS | IRCOMM_DTR;
        else
                self->settings.dte &= ~(IRCOMM_RTS | IRCOMM_DTR);

        ircomm_param_request(self, IRCOMM_DTE, TRUE);
}

static int ircomm_port_carrier_raised(struct tty_port *port)
{
        struct ircomm_tty_cb *self = container_of(port, struct ircomm_tty_cb,
                        port);
        return self->settings.dce & IRCOMM_CD;
}

static const struct tty_port_operations ircomm_port_ops = {
        .dtr_rts = ircomm_port_raise_dtr_rts,
        .carrier_raised = ircomm_port_carrier_raised,
};

/*
 * Function ircomm_tty_init()
 *
 *    Init IrCOMM TTY layer/driver
 *
 */
static int __init ircomm_tty_init(void)
{
        driver = alloc_tty_driver(IRCOMM_TTY_PORTS);
        if (!driver)
                return -ENOMEM;
        ircomm_tty = hashbin_new(HB_LOCK);
        if (ircomm_tty == NULL) {
                net_err_ratelimited("%s(), can't allocate hashbin!\n",
                                    __func__);
                put_tty_driver(driver);
                return -ENOMEM;
        }

        driver->driver_name     = "ircomm";
        driver->name            = "ircomm";
        driver->major           = IRCOMM_TTY_MAJOR;
        driver->minor_start     = IRCOMM_TTY_MINOR;
        driver->type            = TTY_DRIVER_TYPE_SERIAL;
        driver->subtype         = SERIAL_TYPE_NORMAL;
        driver->init_termios    = tty_std_termios;
        driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
        driver->flags           = TTY_DRIVER_REAL_RAW;
        tty_set_operations(driver, &ops);
        if (tty_register_driver(driver)) {
                net_err_ratelimited("%s(): Couldn't register serial driver\n",
                                    __func__);
                put_tty_driver(driver);
                return -1;
        }
        return 0;
}

static void __exit __ircomm_tty_cleanup(struct ircomm_tty_cb *self)
{
        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        ircomm_tty_shutdown(self);

        self->magic = 0;
        tty_port_destroy(&self->port);
        kfree(self);
}

/*
 * Function ircomm_tty_cleanup ()
 *
 *    Remove IrCOMM TTY layer/driver
 *
 */
static void __exit ircomm_tty_cleanup(void)
{
        int ret;

        ret = tty_unregister_driver(driver);
        if (ret) {
                net_err_ratelimited("%s(), failed to unregister driver\n",
                                    __func__);
                return;
        }

        hashbin_delete(ircomm_tty, (FREE_FUNC) __ircomm_tty_cleanup);
        put_tty_driver(driver);
}

/*
 * Function ircomm_startup (self)
 *
 *
 *
 */
static int ircomm_tty_startup(struct ircomm_tty_cb *self)
{
        notify_t notify;
        int ret = -ENODEV;

        IRDA_ASSERT(self != NULL, return -1;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);

        /* Check if already open */
        if (test_and_set_bit(ASYNCB_INITIALIZED, &self->port.flags)) {
                pr_debug("%s(), already open so break out!\n", __func__);
                return 0;
        }

        /* Register with IrCOMM */
        irda_notify_init(&notify);
        /* These callbacks we must handle ourselves */
        notify.data_indication       = ircomm_tty_data_indication;
        notify.udata_indication      = ircomm_tty_control_indication;
        notify.flow_indication       = ircomm_tty_flow_indication;

        /* Use the ircomm_tty interface for these ones */
        notify.disconnect_indication = ircomm_tty_disconnect_indication;
        notify.connect_confirm       = ircomm_tty_connect_confirm;
        notify.connect_indication    = ircomm_tty_connect_indication;
        strlcpy(notify.name, "ircomm_tty", sizeof(notify.name));
        notify.instance = self;

        if (!self->ircomm) {
                self->ircomm = ircomm_open(&notify, self->service_type,
                                           self->line);
        }
        if (!self->ircomm)
                goto err;

        self->slsap_sel = self->ircomm->slsap_sel;

        /* Connect IrCOMM link with remote device */
        ret = ircomm_tty_attach_cable(self);
        if (ret < 0) {
                net_err_ratelimited("%s(), error attaching cable!\n", __func__);
                goto err;
        }

        return 0;
err:
        clear_bit(ASYNCB_INITIALIZED, &self->port.flags);
        return ret;
}

/*
 * Function ircomm_block_til_ready (self, filp)
 *
 *
 *
 */
static int ircomm_tty_block_til_ready(struct ircomm_tty_cb *self,
                struct tty_struct *tty, struct file *filp)
{
        struct tty_port *port = &self->port;
        DECLARE_WAITQUEUE(wait, current);
        int             retval;
        int             do_clocal = 0;
        unsigned long   flags;

        /*
         * If non-blocking mode is set, or the port is not enabled,
         * then make the check up front and then exit.
         */
        if (test_bit(TTY_IO_ERROR, &tty->flags)) {
                port->flags |= ASYNC_NORMAL_ACTIVE;
                return 0;
        }

        if (filp->f_flags & O_NONBLOCK) {
                /* nonblock mode is set */
                if (tty->termios.c_cflag & CBAUD)
                        tty_port_raise_dtr_rts(port);
                port->flags |= ASYNC_NORMAL_ACTIVE;
                pr_debug("%s(), O_NONBLOCK requested!\n", __func__);
                return 0;
        }

        if (tty->termios.c_cflag & CLOCAL) {
                pr_debug("%s(), doing CLOCAL!\n", __func__);
                do_clocal = 1;
        }

        /* Wait for carrier detect and the line to become
         * free (i.e., not in use by the callout).  While we are in
         * this loop, port->count is dropped by one, so that
         * mgsl_close() knows when to free things.  We restore it upon
         * exit, either normal or abnormal.
         */

        retval = 0;
        add_wait_queue(&port->open_wait, &wait);

        pr_debug("%s(%d):block_til_ready before block on %s open_count=%d\n",
                 __FILE__, __LINE__, tty->driver->name, port->count);

        spin_lock_irqsave(&port->lock, flags);
        port->count--;
        port->blocked_open++;
        spin_unlock_irqrestore(&port->lock, flags);

        while (1) {
                if (C_BAUD(tty) && test_bit(ASYNCB_INITIALIZED, &port->flags))
                        tty_port_raise_dtr_rts(port);

                set_current_state(TASK_INTERRUPTIBLE);

                if (tty_hung_up_p(filp) ||
                    !test_bit(ASYNCB_INITIALIZED, &port->flags)) {
                        retval = (port->flags & ASYNC_HUP_NOTIFY) ?
                                        -EAGAIN : -ERESTARTSYS;
                        break;
                }

                /*
                 * Check if link is ready now. Even if CLOCAL is
                 * specified, we cannot return before the IrCOMM link is
                 * ready
                 */
                if ((do_clocal || tty_port_carrier_raised(port)) &&
                    self->state == IRCOMM_TTY_READY)
                {
                        break;
                }

                if (signal_pending(current)) {
                        retval = -ERESTARTSYS;
                        break;
                }

                pr_debug("%s(%d):block_til_ready blocking on %s open_count=%d\n",
                         __FILE__, __LINE__, tty->driver->name, port->count);

                schedule();
        }

        __set_current_state(TASK_RUNNING);
        remove_wait_queue(&port->open_wait, &wait);

        spin_lock_irqsave(&port->lock, flags);
        if (!tty_hung_up_p(filp))
                port->count++;
        port->blocked_open--;
        spin_unlock_irqrestore(&port->lock, flags);

        pr_debug("%s(%d):block_til_ready after blocking on %s open_count=%d\n",
                 __FILE__, __LINE__, tty->driver->name, port->count);

        if (!retval)
                port->flags |= ASYNC_NORMAL_ACTIVE;

        return retval;
}


static int ircomm_tty_install(struct tty_driver *driver, struct tty_struct *tty)
{
        struct ircomm_tty_cb *self;
        unsigned int line = tty->index;

        /* Check if instance already exists */
        self = hashbin_lock_find(ircomm_tty, line, NULL);
        if (!self) {
                /* No, so make new instance */
                self = kzalloc(sizeof(struct ircomm_tty_cb), GFP_KERNEL);
                if (self == NULL)
                        return -ENOMEM;

                tty_port_init(&self->port);
                self->port.ops = &ircomm_port_ops;
                self->magic = IRCOMM_TTY_MAGIC;
                self->flow = FLOW_STOP;

                self->line = line;
                INIT_WORK(&self->tqueue, ircomm_tty_do_softint);
                self->max_header_size = IRCOMM_TTY_HDR_UNINITIALISED;
                self->max_data_size = IRCOMM_TTY_DATA_UNINITIALISED;

                /* Init some important stuff */
                init_timer(&self->watchdog_timer);
                spin_lock_init(&self->spinlock);

                /*
                 * Force TTY into raw mode by default which is usually what
                 * we want for IrCOMM and IrLPT. This way applications will
                 * not have to twiddle with printcap etc.
                 *
                 * Note this is completely usafe and doesn't work properly
                 */
                tty->termios.c_iflag = 0;
                tty->termios.c_oflag = 0;

                /* Insert into hash */
                hashbin_insert(ircomm_tty, (irda_queue_t *) self, line, NULL);
        }

        tty->driver_data = self;

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

/*
 * Function ircomm_tty_open (tty, filp)
 *
 *    This routine is called when a particular tty device is opened. This
 *    routine is mandatory; if this routine is not filled in, the attempted
 *    open will fail with ENODEV.
 */
static int ircomm_tty_open(struct tty_struct *tty, struct file *filp)
{
        struct ircomm_tty_cb *self = tty->driver_data;
        unsigned long   flags;
        int ret;

        /* ++ is not atomic, so this should be protected - Jean II */
        spin_lock_irqsave(&self->port.lock, flags);
        self->port.count++;
        spin_unlock_irqrestore(&self->port.lock, flags);
        tty_port_tty_set(&self->port, tty);

        pr_debug("%s(), %s%d, count = %d\n", __func__ , tty->driver->name,
                 self->line, self->port.count);

        /* Not really used by us, but lets do it anyway */
        self->port.low_latency = (self->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;

        /* Check if this is a "normal" ircomm device, or an irlpt device */
        if (self->line < 0x10) {
                self->service_type = IRCOMM_3_WIRE | IRCOMM_9_WIRE;
                self->settings.service_type = IRCOMM_9_WIRE; /* 9 wire as default */
                /* Jan Kiszka -> add DSR/RI -> Conform to IrCOMM spec */
                self->settings.dce = IRCOMM_CTS | IRCOMM_CD | IRCOMM_DSR | IRCOMM_RI; /* Default line settings */
                pr_debug("%s(), IrCOMM device\n", __func__);
        } else {
                pr_debug("%s(), IrLPT device\n", __func__);
                self->service_type = IRCOMM_3_WIRE_RAW;
                self->settings.service_type = IRCOMM_3_WIRE_RAW; /* Default */
        }

        ret = ircomm_tty_startup(self);
        if (ret)
                return ret;

        ret = ircomm_tty_block_til_ready(self, tty, filp);
        if (ret) {
                pr_debug("%s(), returning after block_til_ready with %d\n",
                         __func__, ret);

                return ret;
        }
        return 0;
}

/*
 * Function ircomm_tty_close (tty, filp)
 *
 *    This routine is called when a particular tty device is closed.
 *
 */
static void ircomm_tty_close(struct tty_struct *tty, struct file *filp)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
        struct tty_port *port = &self->port;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        if (tty_port_close_start(port, tty, filp) == 0)
                return;

        ircomm_tty_shutdown(self);

        tty_driver_flush_buffer(tty);

        tty_port_close_end(port, tty);
        tty_port_tty_set(port, NULL);
}

/*
 * Function ircomm_tty_flush_buffer (tty)
 *
 *
 *
 */
static void ircomm_tty_flush_buffer(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        /*
         * Let do_softint() do this to avoid race condition with
         * do_softint() ;-)
         */
        schedule_work(&self->tqueue);
}

/*
 * Function ircomm_tty_do_softint (work)
 *
 *    We use this routine to give the write wakeup to the user at at a
 *    safe time (as fast as possible after write have completed). This
 *    can be compared to the Tx interrupt.
 */
static void ircomm_tty_do_softint(struct work_struct *work)
{
        struct ircomm_tty_cb *self =
                container_of(work, struct ircomm_tty_cb, tqueue);
        struct tty_struct *tty;
        unsigned long flags;
        struct sk_buff *skb, *ctrl_skb;

        if (!self || self->magic != IRCOMM_TTY_MAGIC)
                return;

        tty = tty_port_tty_get(&self->port);
        if (!tty)
                return;

        /* Unlink control buffer */
        spin_lock_irqsave(&self->spinlock, flags);

        ctrl_skb = self->ctrl_skb;
        self->ctrl_skb = NULL;

        spin_unlock_irqrestore(&self->spinlock, flags);

        /* Flush control buffer if any */
        if(ctrl_skb) {
                if(self->flow == FLOW_START)
                        ircomm_control_request(self->ircomm, ctrl_skb);
                /* Drop reference count - see ircomm_ttp_data_request(). */
                dev_kfree_skb(ctrl_skb);
        }

        if (tty->hw_stopped)
                goto put;

        /* Unlink transmit buffer */
        spin_lock_irqsave(&self->spinlock, flags);

        skb = self->tx_skb;
        self->tx_skb = NULL;

        spin_unlock_irqrestore(&self->spinlock, flags);

        /* Flush transmit buffer if any */
        if (skb) {
                ircomm_tty_do_event(self, IRCOMM_TTY_DATA_REQUEST, skb, NULL);
                /* Drop reference count - see ircomm_ttp_data_request(). */
                dev_kfree_skb(skb);
        }

        /* Check if user (still) wants to be waken up */
        tty_wakeup(tty);
put:
        tty_kref_put(tty);
}

/*
 * Function ircomm_tty_write (tty, buf, count)
 *
 *    This routine is called by the kernel to write a series of characters
 *    to the tty device. The characters may come from user space or kernel
 *    space. This routine will return the number of characters actually
 *    accepted for writing. This routine is mandatory.
 */
static int ircomm_tty_write(struct tty_struct *tty,
                            const unsigned char *buf, int count)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
        unsigned long flags;
        struct sk_buff *skb;
        int tailroom = 0;
        int len = 0;
        int size;

        pr_debug("%s(), count=%d, hw_stopped=%d\n", __func__ , count,
                 tty->hw_stopped);

        IRDA_ASSERT(self != NULL, return -1;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);

        /* We may receive packets from the TTY even before we have finished
         * our setup. Not cool.
         * The problem is that we don't know the final header and data size
         * to create the proper skb, so any skb we would create would have
         * bogus header and data size, so need care.
         * We use a bogus header size to safely detect this condition.
         * Another problem is that hw_stopped was set to 0 way before it
         * should be, so we would drop this skb. It should now be fixed.
         * One option is to not accept data until we are properly setup.
         * But, I suspect that when it happens, the ppp line discipline
         * just "drops" the data, which might screw up connect scripts.
         * The second option is to create a "safe skb", with large header
         * and small size (see ircomm_tty_open() for values).
         * We just need to make sure that when the real values get filled,
         * we don't mess up the original "safe skb" (see tx_data_size).
         * Jean II */
        if (self->max_header_size == IRCOMM_TTY_HDR_UNINITIALISED) {
                pr_debug("%s() : not initialised\n", __func__);
#ifdef IRCOMM_NO_TX_BEFORE_INIT
                /* We didn't consume anything, TTY will retry */
                return 0;
#endif
        }

        if (count < 1)
                return 0;

        /* Protect our manipulation of self->tx_skb and related */
        spin_lock_irqsave(&self->spinlock, flags);

        /* Fetch current transmit buffer */
        skb = self->tx_skb;

        /*
         * Send out all the data we get, possibly as multiple fragmented
         * frames, but this will only happen if the data is larger than the
         * max data size. The normal case however is just the opposite, and
         * this function may be called multiple times, and will then actually
         * defragment the data and send it out as one packet as soon as
         * possible, but at a safer point in time
         */
        while (count) {
                size = count;

                /* Adjust data size to the max data size */
                if (size > self->max_data_size)
                        size = self->max_data_size;

                /*
                 * Do we already have a buffer ready for transmit, or do
                 * we need to allocate a new frame
                 */
                if (skb) {
                        /*
                         * Any room for more data at the end of the current
                         * transmit buffer? Cannot use skb_tailroom, since
                         * dev_alloc_skb gives us a larger skb than we
                         * requested
                         * Note : use tx_data_size, because max_data_size
                         * may have changed and we don't want to overwrite
                         * the skb. - Jean II
                         */
                        if ((tailroom = (self->tx_data_size - skb->len)) > 0) {
                                /* Adjust data to tailroom */
                                if (size > tailroom)
                                        size = tailroom;
                        } else {
                                /*
                                 * Current transmit frame is full, so break
                                 * out, so we can send it as soon as possible
                                 */
                                break;
                        }
                } else {
                        /* Prepare a full sized frame */
                        skb = alloc_skb(self->max_data_size+
                                        self->max_header_size,
                                        GFP_ATOMIC);
                        if (!skb) {
                                spin_unlock_irqrestore(&self->spinlock, flags);
                                return -ENOBUFS;
                        }
                        skb_reserve(skb, self->max_header_size);
                        self->tx_skb = skb;
                        /* Remember skb size because max_data_size may
                         * change later on - Jean II */
                        self->tx_data_size = self->max_data_size;
                }

                /* Copy data */
                memcpy(skb_put(skb,size), buf + len, size);

                count -= size;
                len += size;
        }

        spin_unlock_irqrestore(&self->spinlock, flags);

        /*
         * Schedule a new thread which will transmit the frame as soon
         * as possible, but at a safe point in time. We do this so the
         * "user" can give us data multiple times, as PPP does (because of
         * its 256 byte tx buffer). We will then defragment and send out
         * all this data as one single packet.
         */
        schedule_work(&self->tqueue);

        return len;
}

/*
 * Function ircomm_tty_write_room (tty)
 *
 *    This routine returns the numbers of characters the tty driver will
 *    accept for queuing to be written. This number is subject to change as
 *    output buffers get emptied, or if the output flow control is acted.
 */
static int ircomm_tty_write_room(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
        unsigned long flags;
        int ret;

        IRDA_ASSERT(self != NULL, return -1;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);

#ifdef IRCOMM_NO_TX_BEFORE_INIT
        /* max_header_size tells us if the channel is initialised or not. */
        if (self->max_header_size == IRCOMM_TTY_HDR_UNINITIALISED)
                /* Don't bother us yet */
                return 0;
#endif

        /* Check if we are allowed to transmit any data.
         * hw_stopped is the regular flow control.
         * Jean II */
        if (tty->hw_stopped)
                ret = 0;
        else {
                spin_lock_irqsave(&self->spinlock, flags);
                if (self->tx_skb)
                        ret = self->tx_data_size - self->tx_skb->len;
                else
                        ret = self->max_data_size;
                spin_unlock_irqrestore(&self->spinlock, flags);
        }
        pr_debug("%s(), ret=%d\n", __func__ , ret);

        return ret;
}

/*
 * Function ircomm_tty_wait_until_sent (tty, timeout)
 *
 *    This routine waits until the device has written out all of the
 *    characters in its transmitter FIFO.
 */
static void ircomm_tty_wait_until_sent(struct tty_struct *tty, int timeout)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
        unsigned long orig_jiffies, poll_time;
        unsigned long flags;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        orig_jiffies = jiffies;

        /* Set poll time to 200 ms */
        poll_time = msecs_to_jiffies(200);
        if (timeout)
                poll_time = min_t(unsigned long, timeout, poll_time);

        spin_lock_irqsave(&self->spinlock, flags);
        while (self->tx_skb && self->tx_skb->len) {
                spin_unlock_irqrestore(&self->spinlock, flags);
                schedule_timeout_interruptible(poll_time);
                spin_lock_irqsave(&self->spinlock, flags);
                if (signal_pending(current))
                        break;
                if (timeout && time_after(jiffies, orig_jiffies + timeout))
                        break;
        }
        spin_unlock_irqrestore(&self->spinlock, flags);
        __set_current_state(TASK_RUNNING);
}

/*
 * Function ircomm_tty_throttle (tty)
 *
 *    This routine notifies the tty driver that input buffers for the line
 *    discipline are close to full, and it should somehow signal that no
 *    more characters should be sent to the tty.
 */
static void ircomm_tty_throttle(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        /* Software flow control? */
        if (I_IXOFF(tty))
                ircomm_tty_send_xchar(tty, STOP_CHAR(tty));

        /* Hardware flow control? */
        if (tty->termios.c_cflag & CRTSCTS) {
                self->settings.dte &= ~IRCOMM_RTS;
                self->settings.dte |= IRCOMM_DELTA_RTS;

                ircomm_param_request(self, IRCOMM_DTE, TRUE);
        }

        ircomm_flow_request(self->ircomm, FLOW_STOP);
}

/*
 * Function ircomm_tty_unthrottle (tty)
 *
 *    This routine notifies the tty drivers that it should signals that
 *    characters can now be sent to the tty without fear of overrunning the
 *    input buffers of the line disciplines.
 */
static void ircomm_tty_unthrottle(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        /* Using software flow control? */
        if (I_IXOFF(tty)) {
                ircomm_tty_send_xchar(tty, START_CHAR(tty));
        }

        /* Using hardware flow control? */
        if (tty->termios.c_cflag & CRTSCTS) {
                self->settings.dte |= (IRCOMM_RTS|IRCOMM_DELTA_RTS);

                ircomm_param_request(self, IRCOMM_DTE, TRUE);
                pr_debug("%s(), FLOW_START\n", __func__);
        }
        ircomm_flow_request(self->ircomm, FLOW_START);
}

/*
 * Function ircomm_tty_chars_in_buffer (tty)
 *
 *    Indicates if there are any data in the buffer
 *
 */
static int ircomm_tty_chars_in_buffer(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
        unsigned long flags;
        int len = 0;

        IRDA_ASSERT(self != NULL, return -1;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);

        spin_lock_irqsave(&self->spinlock, flags);

        if (self->tx_skb)
                len = self->tx_skb->len;

        spin_unlock_irqrestore(&self->spinlock, flags);

        return len;
}

static void ircomm_tty_shutdown(struct ircomm_tty_cb *self)
{
        unsigned long flags;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        if (!test_and_clear_bit(ASYNCB_INITIALIZED, &self->port.flags))
                return;

        ircomm_tty_detach_cable(self);

        spin_lock_irqsave(&self->spinlock, flags);

        del_timer(&self->watchdog_timer);

        /* Free parameter buffer */
        if (self->ctrl_skb) {
                dev_kfree_skb(self->ctrl_skb);
                self->ctrl_skb = NULL;
        }

        /* Free transmit buffer */
        if (self->tx_skb) {
                dev_kfree_skb(self->tx_skb);
                self->tx_skb = NULL;
        }

        if (self->ircomm) {
                ircomm_close(self->ircomm);
                self->ircomm = NULL;
        }

        spin_unlock_irqrestore(&self->spinlock, flags);
}

/*
 * Function ircomm_tty_hangup (tty)
 *
 *    This routine notifies the tty driver that it should hangup the tty
 *    device.
 *
 */
static void ircomm_tty_hangup(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;
        struct tty_port *port = &self->port;
        unsigned long   flags;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        /* ircomm_tty_flush_buffer(tty); */
        ircomm_tty_shutdown(self);

        spin_lock_irqsave(&port->lock, flags);
        port->flags &= ~ASYNC_NORMAL_ACTIVE;
        if (port->tty) {
                set_bit(TTY_IO_ERROR, &port->tty->flags);
                tty_kref_put(port->tty);
        }
        port->tty = NULL;
        port->count = 0;
        spin_unlock_irqrestore(&port->lock, flags);

        wake_up_interruptible(&port->open_wait);
}

/*
 * Function ircomm_tty_send_xchar (tty, ch)
 *
 *    This routine is used to send a high-priority XON/XOFF character to
 *    the device.
 */
static void ircomm_tty_send_xchar(struct tty_struct *tty, char ch)
{
        pr_debug("%s(), not impl\n", __func__);
}

/*
 * Function ircomm_tty_start (tty)
 *
 *    This routine notifies the tty driver that it resume sending
 *    characters to the tty device.
 */
void ircomm_tty_start(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;

        ircomm_flow_request(self->ircomm, FLOW_START);
}

/*
 * Function ircomm_tty_stop (tty)
 *
 *     This routine notifies the tty driver that it should stop outputting
 *     characters to the tty device.
 */
static void ircomm_tty_stop(struct tty_struct *tty)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) tty->driver_data;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        ircomm_flow_request(self->ircomm, FLOW_STOP);
}

/*
 * Function ircomm_check_modem_status (self)
 *
 *    Check for any changes in the DCE's line settings. This function should
 *    be called whenever the dce parameter settings changes, to update the
 *    flow control settings and other things
 */
void ircomm_tty_check_modem_status(struct ircomm_tty_cb *self)
{
        struct tty_struct *tty;
        int status;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        tty = tty_port_tty_get(&self->port);

        status = self->settings.dce;

        if (status & IRCOMM_DCE_DELTA_ANY) {
                /*wake_up_interruptible(&self->delta_msr_wait);*/
        }
        if ((self->port.flags & ASYNC_CHECK_CD) && (status & IRCOMM_DELTA_CD)) {
                pr_debug("%s(), ircomm%d CD now %s...\n", __func__ , self->line,
                         (status & IRCOMM_CD) ? "on" : "off");

                if (status & IRCOMM_CD) {
                        wake_up_interruptible(&self->port.open_wait);
                } else {
                        pr_debug("%s(), Doing serial hangup..\n", __func__);
                        if (tty)
                                tty_hangup(tty);

                        /* Hangup will remote the tty, so better break out */
                        goto put;
                }
        }
        if (tty && tty_port_cts_enabled(&self->port)) {
                if (tty->hw_stopped) {
                        if (status & IRCOMM_CTS) {
                                pr_debug("%s(), CTS tx start...\n", __func__);
                                tty->hw_stopped = 0;

                                /* Wake up processes blocked on open */
                                wake_up_interruptible(&self->port.open_wait);

                                schedule_work(&self->tqueue);
                                goto put;
                        }
                } else {
                        if (!(status & IRCOMM_CTS)) {
                                pr_debug("%s(), CTS tx stop...\n", __func__);
                                tty->hw_stopped = 1;
                        }
                }
        }
put:
        tty_kref_put(tty);
}

/*
 * Function ircomm_tty_data_indication (instance, sap, skb)
 *
 *    Handle incoming data, and deliver it to the line discipline
 *
 */
static int ircomm_tty_data_indication(void *instance, void *sap,
                                      struct sk_buff *skb)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) instance;
        struct tty_struct *tty;

        IRDA_ASSERT(self != NULL, return -1;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);
        IRDA_ASSERT(skb != NULL, return -1;);

        tty = tty_port_tty_get(&self->port);
        if (!tty) {
                pr_debug("%s(), no tty!\n", __func__);
                return 0;
        }

        /*
         * If we receive data when hardware is stopped then something is wrong.
         * We try to poll the peers line settings to check if we are up todate.
         * Devices like WinCE can do this, and since they don't send any
         * params, we can just as well declare the hardware for running.
         */
        if (tty->hw_stopped && (self->flow == FLOW_START)) {
                pr_debug("%s(), polling for line settings!\n", __func__);
                ircomm_param_request(self, IRCOMM_POLL, TRUE);

                /* We can just as well declare the hardware for running */
                ircomm_tty_send_initial_parameters(self);
                ircomm_tty_link_established(self);
        }
        tty_kref_put(tty);

        /*
         * Use flip buffer functions since the code may be called from interrupt
         * context
         */
        tty_insert_flip_string(&self->port, skb->data, skb->len);
        tty_flip_buffer_push(&self->port);

        /* No need to kfree_skb - see ircomm_ttp_data_indication() */

        return 0;
}

/*
 * Function ircomm_tty_control_indication (instance, sap, skb)
 *
 *    Parse all incoming parameters (easy!)
 *
 */
static int ircomm_tty_control_indication(void *instance, void *sap,
                                         struct sk_buff *skb)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) instance;
        int clen;

        IRDA_ASSERT(self != NULL, return -1;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return -1;);
        IRDA_ASSERT(skb != NULL, return -1;);

        clen = skb->data[0];

        irda_param_extract_all(self, skb->data+1, IRDA_MIN(skb->len-1, clen),
                               &ircomm_param_info);

        /* No need to kfree_skb - see ircomm_control_indication() */

        return 0;
}

/*
 * Function ircomm_tty_flow_indication (instance, sap, cmd)
 *
 *    This function is called by IrTTP when it wants us to slow down the
 *    transmission of data. We just mark the hardware as stopped, and wait
 *    for IrTTP to notify us that things are OK again.
 */
static void ircomm_tty_flow_indication(void *instance, void *sap,
                                       LOCAL_FLOW cmd)
{
        struct ircomm_tty_cb *self = (struct ircomm_tty_cb *) instance;
        struct tty_struct *tty;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(self->magic == IRCOMM_TTY_MAGIC, return;);

        tty = tty_port_tty_get(&self->port);

        switch (cmd) {
        case FLOW_START:
                pr_debug("%s(), hw start!\n", __func__);
                if (tty)
                        tty->hw_stopped = 0;

                /* ircomm_tty_do_softint will take care of the rest */
                schedule_work(&self->tqueue);
                break;
        default:  /* If we get here, something is very wrong, better stop */
        case FLOW_STOP:
                pr_debug("%s(), hw stopped!\n", __func__);
                if (tty)
                        tty->hw_stopped = 1;
                break;
        }

        tty_kref_put(tty);
        self->flow = cmd;
}

#ifdef CONFIG_PROC_FS
static void ircomm_tty_line_info(struct ircomm_tty_cb *self, struct seq_file *m)
{
        struct tty_struct *tty;
        char sep;

        seq_printf(m, "State: %s\n", ircomm_tty_state[self->state]);

        seq_puts(m, "Service type: ");
        if (self->service_type & IRCOMM_9_WIRE)
                seq_puts(m, "9_WIRE");
        else if (self->service_type & IRCOMM_3_WIRE)
                seq_puts(m, "3_WIRE");
        else if (self->service_type & IRCOMM_3_WIRE_RAW)
                seq_puts(m, "3_WIRE_RAW");
        else
                seq_puts(m, "No common service type!\n");
        seq_putc(m, '\n');

        seq_printf(m, "Port name: %s\n", self->settings.port_name);

        seq_printf(m, "DTE status:");
        sep = ' ';
        if (self->settings.dte & IRCOMM_RTS) {
                seq_printf(m, "%cRTS", sep);
                sep = '|';
        }
        if (self->settings.dte & IRCOMM_DTR) {
                seq_printf(m, "%cDTR", sep);
                sep = '|';
        }
        seq_putc(m, '\n');

        seq_puts(m, "DCE status:");
        sep = ' ';
        if (self->settings.dce & IRCOMM_CTS) {
                seq_printf(m, "%cCTS", sep);
                sep = '|';
        }
        if (self->settings.dce & IRCOMM_DSR) {
                seq_printf(m, "%cDSR", sep);
                sep = '|';
        }
        if (self->settings.dce & IRCOMM_CD) {
                seq_printf(m, "%cCD", sep);
                sep = '|';
        }
        if (self->settings.dce & IRCOMM_RI) {
                seq_printf(m, "%cRI", sep);
                sep = '|';
        }
        seq_putc(m, '\n');

        seq_puts(m, "Configuration: ");
        if (!self->settings.null_modem)
                seq_puts(m, "DTE <-> DCE\n");
        else
                seq_puts(m, "DTE <-> DTE (null modem emulation)\n");

        seq_printf(m, "Data rate: %d\n", self->settings.data_rate);

        seq_puts(m, "Flow control:");
        sep = ' ';
        if (self->settings.flow_control & IRCOMM_XON_XOFF_IN) {
                seq_printf(m, "%cXON_XOFF_IN", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_XON_XOFF_OUT) {
                seq_printf(m, "%cXON_XOFF_OUT", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_RTS_CTS_IN) {
                seq_printf(m, "%cRTS_CTS_IN", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_RTS_CTS_OUT) {
                seq_printf(m, "%cRTS_CTS_OUT", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_DSR_DTR_IN) {
                seq_printf(m, "%cDSR_DTR_IN", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_DSR_DTR_OUT) {
                seq_printf(m, "%cDSR_DTR_OUT", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_ENQ_ACK_IN) {
                seq_printf(m, "%cENQ_ACK_IN", sep);
                sep = '|';
        }
        if (self->settings.flow_control & IRCOMM_ENQ_ACK_OUT) {
                seq_printf(m, "%cENQ_ACK_OUT", sep);
                sep = '|';
        }
        seq_putc(m, '\n');

        seq_puts(m, "Flags:");
        sep = ' ';
        if (tty_port_cts_enabled(&self->port)) {
                seq_printf(m, "%cASYNC_CTS_FLOW", sep);
                sep = '|';
        }
        if (self->port.flags & ASYNC_CHECK_CD) {
                seq_printf(m, "%cASYNC_CHECK_CD", sep);
                sep = '|';
        }
        if (self->port.flags & ASYNC_INITIALIZED) {
                seq_printf(m, "%cASYNC_INITIALIZED", sep);
                sep = '|';
        }
        if (self->port.flags & ASYNC_LOW_LATENCY) {
                seq_printf(m, "%cASYNC_LOW_LATENCY", sep);
                sep = '|';
        }
        if (self->port.flags & ASYNC_CLOSING) {
                seq_printf(m, "%cASYNC_CLOSING", sep);
                sep = '|';
        }
        if (self->port.flags & ASYNC_NORMAL_ACTIVE) {
                seq_printf(m, "%cASYNC_NORMAL_ACTIVE", sep);
                sep = '|';
        }
        seq_putc(m, '\n');

        seq_printf(m, "Role: %s\n", self->client ? "client" : "server");
        seq_printf(m, "Open count: %d\n", self->port.count);
        seq_printf(m, "Max data size: %d\n", self->max_data_size);
        seq_printf(m, "Max header size: %d\n", self->max_header_size);

        tty = tty_port_tty_get(&self->port);
        if (tty) {
                seq_printf(m, "Hardware: %s\n",
                               tty->hw_stopped ? "Stopped" : "Running");
                tty_kref_put(tty);
        }
}

static int ircomm_tty_proc_show(struct seq_file *m, void *v)
{
        struct ircomm_tty_cb *self;
        unsigned long flags;

        spin_lock_irqsave(&ircomm_tty->hb_spinlock, flags);

        self = (struct ircomm_tty_cb *) hashbin_get_first(ircomm_tty);
        while (self != NULL) {
                if (self->magic != IRCOMM_TTY_MAGIC)
                        break;

                ircomm_tty_line_info(self, m);
                self = (struct ircomm_tty_cb *) hashbin_get_next(ircomm_tty);
        }
        spin_unlock_irqrestore(&ircomm_tty->hb_spinlock, flags);
        return 0;
}

static int ircomm_tty_proc_open(struct inode *inode, struct file *file)
{
        return single_open(file, ircomm_tty_proc_show, NULL);
}

static const struct file_operations ircomm_tty_proc_fops = {
        .owner          = THIS_MODULE,
        .open           = ircomm_tty_proc_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};
#endif /* CONFIG_PROC_FS */

MODULE_AUTHOR("Dag Brattli <dagb@cs.uit.no>");
MODULE_DESCRIPTION("IrCOMM serial TTY driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(IRCOMM_TTY_MAJOR);

module_init(ircomm_tty_init);
module_exit(ircomm_tty_cleanup);