drivers/net: Remove pointless checks for NULL prior to calling kfree()

[safe/jmp/linux-2.6] / drivers / net / irda / irport.c

/*********************************************************************
 * 
 * Filename:      irport.c
 * Version:       1.0
 * Description:   Half duplex serial port SIR driver for IrDA. 
 * Status:        Experimental.
 * Author:        Dag Brattli <dagb@cs.uit.no>
 * Created at:    Sun Aug  3 13:49:59 1997
 * Modified at:   Fri Jan 28 20:22:38 2000
 * Modified by:   Dag Brattli <dagb@cs.uit.no>
 * Sources:       serial.c by Linus Torvalds 
 * 
 *     Copyright (c) 1997, 1998, 1999-2000 Dag Brattli, All Rights Reserved.
 *     Copyright (c) 2000-2003 Jean Tourrilhes, All Rights Reserved.
 *     
 *     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, write to the Free Software 
 *     Foundation, Inc., 59 Temple Place, Suite 330, Boston, 
 *     MA 02111-1307 USA
 *
 *     This driver is ment to be a small half duplex serial driver to be
 *     used for IR-chipsets that has a UART (16550) compatibility mode. 
 *     Eventually it will replace irtty, because of irtty has some 
 *     problems that is hard to get around when we don't have control
 *     over the serial driver. This driver may also be used by FIR 
 *     drivers to handle SIR mode for them.
 *
 ********************************************************************/

#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/serial_reg.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/rtnetlink.h>
#include <linux/bitops.h>

#include <asm/system.h>
#include <asm/io.h>

#include <net/irda/irda.h>
#include <net/irda/wrapper.h>
#include "irport.h"

#define IO_EXTENT 8

/* 
 * Currently you'll need to set these values using insmod like this:
 * insmod irport io=0x3e8 irq=11
 */
static unsigned int io[]  = { ~0, ~0, ~0, ~0 };
static unsigned int irq[] = { 0, 0, 0, 0 };

static unsigned int qos_mtt_bits = 0x03;

static struct irport_cb *dev_self[] = { NULL, NULL, NULL, NULL};
static char *driver_name = "irport";

static inline void irport_write_wakeup(struct irport_cb *self);
static inline int  irport_write(int iobase, int fifo_size, __u8 *buf, int len);
static inline void irport_receive(struct irport_cb *self);

static int  irport_net_ioctl(struct net_device *dev, struct ifreq *rq, 
                             int cmd);
static inline int  irport_is_receiving(struct irport_cb *self);
static int  irport_set_dtr_rts(struct net_device *dev, int dtr, int rts);
static int  irport_raw_write(struct net_device *dev, __u8 *buf, int len);
static struct net_device_stats *irport_net_get_stats(struct net_device *dev);
static int irport_change_speed_complete(struct irda_task *task);
static void irport_timeout(struct net_device *dev);

static irqreturn_t irport_interrupt(int irq, void *dev_id,
                                    struct pt_regs *regs);
static int irport_hard_xmit(struct sk_buff *skb, struct net_device *dev);
static void irport_change_speed(void *priv, __u32 speed);
static int irport_net_open(struct net_device *dev);
static int irport_net_close(struct net_device *dev);

static struct irport_cb *
irport_open(int i, unsigned int iobase, unsigned int irq)
{
        struct net_device *dev;
        struct irport_cb *self;

        IRDA_DEBUG(1, "%s()\n", __FUNCTION__);

        /* Lock the port that we need */
        if (!request_region(iobase, IO_EXTENT, driver_name)) {
                IRDA_DEBUG(0, "%s(), can't get iobase of 0x%03x\n",
                           __FUNCTION__, iobase);
                goto err_out1;
        }

        /*
         *  Allocate new instance of the driver
         */
        dev = alloc_irdadev(sizeof(struct irport_cb));
        if (!dev) {
                IRDA_ERROR("%s(), can't allocate memory for "
                           "irda device!\n", __FUNCTION__);
                goto err_out2;
        }

        self = dev->priv;
        spin_lock_init(&self->lock);

        /* Need to store self somewhere */
        dev_self[i] = self;
        self->priv = self;
        self->index = i;

        /* Initialize IO */
        self->io.sir_base  = iobase;
        self->io.sir_ext   = IO_EXTENT;
        self->io.irq       = irq;
        self->io.fifo_size = 16;                /* 16550A and compatible */

        /* Initialize QoS for this device */
        irda_init_max_qos_capabilies(&self->qos);
        
        self->qos.baud_rate.bits = IR_9600|IR_19200|IR_38400|IR_57600|
                IR_115200;

        self->qos.min_turn_time.bits = qos_mtt_bits;
        irda_qos_bits_to_value(&self->qos);
        
        /* Bootstrap ZeroCopy Rx */
        self->rx_buff.truesize = IRDA_SKB_MAX_MTU;
        self->rx_buff.skb = __dev_alloc_skb(self->rx_buff.truesize,
                                            GFP_KERNEL);
        if (self->rx_buff.skb == NULL) {
                IRDA_ERROR("%s(), can't allocate memory for "
                           "receive buffer!\n", __FUNCTION__);
                goto err_out3;
        }
        skb_reserve(self->rx_buff.skb, 1);
        self->rx_buff.head = self->rx_buff.skb->data;
        /* No need to memset the buffer, unless you are really pedantic */

        /* Finish setup the Rx buffer descriptor */
        self->rx_buff.in_frame = FALSE;
        self->rx_buff.state = OUTSIDE_FRAME;
        self->rx_buff.data = self->rx_buff.head;

        /* Specify how much memory we want */
        self->tx_buff.truesize = 4000;
        
        /* Allocate memory if needed */
        if (self->tx_buff.truesize > 0) {
                self->tx_buff.head = (__u8 *) kmalloc(self->tx_buff.truesize, 
                                                      GFP_KERNEL);
                if (self->tx_buff.head == NULL) {
                        IRDA_ERROR("%s(), can't allocate memory for "
                                   "transmit buffer!\n", __FUNCTION__);
                        goto err_out4;
                }
                memset(self->tx_buff.head, 0, self->tx_buff.truesize);
        }       
        self->tx_buff.data = self->tx_buff.head;

        self->netdev = dev;
        /* Keep track of module usage */
        SET_MODULE_OWNER(dev);

        /* May be overridden by piggyback drivers */
        self->interrupt    = irport_interrupt;
        self->change_speed = irport_change_speed;

        /* Override the network functions we need to use */
        dev->hard_start_xmit = irport_hard_xmit;
        dev->tx_timeout      = irport_timeout;
        dev->watchdog_timeo  = HZ;  /* Allow time enough for speed change */
        dev->open            = irport_net_open;
        dev->stop            = irport_net_close;
        dev->get_stats       = irport_net_get_stats;
        dev->do_ioctl        = irport_net_ioctl;

        /* Make ifconfig display some details */
        dev->base_addr = iobase;
        dev->irq = irq;

        if (register_netdev(dev)) {
                IRDA_ERROR("%s(), register_netdev() failed!\n", __FUNCTION__);
                goto err_out5;
        }
        IRDA_MESSAGE("IrDA: Registered device %s (irport io=0x%X irq=%d)\n",
                dev->name, iobase, irq);

        return self;
 err_out5:
        kfree(self->tx_buff.head);
 err_out4:
        kfree_skb(self->rx_buff.skb);
 err_out3:
        free_netdev(dev);
        dev_self[i] = NULL;
 err_out2:
        release_region(iobase, IO_EXTENT);
 err_out1:
        return NULL;
}

static int irport_close(struct irport_cb *self)
{
        IRDA_ASSERT(self != NULL, return -1;);

        /* We are not using any dongle anymore! */
        if (self->dongle)
                irda_device_dongle_cleanup(self->dongle);
        self->dongle = NULL;
        
        /* Remove netdevice */
        unregister_netdev(self->netdev);

        /* Release the IO-port that this driver is using */
        IRDA_DEBUG(0 , "%s(), Releasing Region %03x\n", 
                   __FUNCTION__, self->io.sir_base);
        release_region(self->io.sir_base, self->io.sir_ext);

        kfree(self->tx_buff.head);
        
        if (self->rx_buff.skb)
                kfree_skb(self->rx_buff.skb);
        self->rx_buff.skb = NULL;
        
        /* Remove ourselves */
        dev_self[self->index] = NULL;
        free_netdev(self->netdev);
        
        return 0;
}

static void irport_stop(struct irport_cb *self)
{
        int iobase;

        iobase = self->io.sir_base;

        /* We can't lock, we may be called from a FIR driver - Jean II */

        /* We are not transmitting any more */
        self->transmitting = 0;

        /* Reset UART */
        outb(0, iobase+UART_MCR);
        
        /* Turn off interrupts */
        outb(0, iobase+UART_IER);
}

static void irport_start(struct irport_cb *self)
{
        int iobase;

        iobase = self->io.sir_base;

        irport_stop(self);
        
        /* We can't lock, we may be called from a FIR driver - Jean II */

        /* Initialize UART */
        outb(UART_LCR_WLEN8, iobase+UART_LCR);  /* Reset DLAB */
        outb((UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2), iobase+UART_MCR);
        
        /* Turn on interrups */
        outb(UART_IER_RLSI | UART_IER_RDI |UART_IER_THRI, iobase+UART_IER);
}

/*
 * Function irport_probe (void)
 *
 *    Start IO port 
 *
 */
int irport_probe(int iobase)
{
        IRDA_DEBUG(4, "%s(), iobase=%#x\n", __FUNCTION__, iobase);

        return 0;
}

/*
 * Function irport_get_fcr (speed)
 *
 *    Compute value of fcr
 *
 */
static inline unsigned int irport_get_fcr(__u32 speed)
{
        unsigned int fcr;    /* FIFO control reg */

        /* Enable fifos */
        fcr = UART_FCR_ENABLE_FIFO;

        /* 
         * Use trigger level 1 to avoid 3 ms. timeout delay at 9600 bps, and
         * almost 1,7 ms at 19200 bps. At speeds above that we can just forget
         * about this timeout since it will always be fast enough. 
         */
        if (speed < 38400)
                fcr |= UART_FCR_TRIGGER_1;
        else 
                //fcr |= UART_FCR_TRIGGER_14;
                fcr |= UART_FCR_TRIGGER_8;

        return(fcr);
}
 
/*
 * Function irport_change_speed (self, speed)
 *
 *    Set speed of IrDA port to specified baudrate
 *
 * This function should be called with irq off and spin-lock.
 */
static void irport_change_speed(void *priv, __u32 speed)
{
        struct irport_cb *self = (struct irport_cb *) priv;
        int iobase; 
        unsigned int fcr;    /* FIFO control reg */
        unsigned int lcr;    /* Line control reg */
        int divisor;

        IRDA_ASSERT(self != NULL, return;);
        IRDA_ASSERT(speed != 0, return;);

        IRDA_DEBUG(1, "%s(), Setting speed to: %d - iobase=%#x\n",
                    __FUNCTION__, speed, self->io.sir_base);

        /* We can't lock, we may be called from a FIR driver - Jean II */

        iobase = self->io.sir_base;
        
        /* Update accounting for new speed */
        self->io.speed = speed;

        /* Turn off interrupts */
        outb(0, iobase+UART_IER); 

        divisor = SPEED_MAX/speed;
        
        /* Get proper fifo configuration */
        fcr = irport_get_fcr(speed);

        /* IrDA ports use 8N1 */
        lcr = UART_LCR_WLEN8;
        
        outb(UART_LCR_DLAB | lcr, iobase+UART_LCR); /* Set DLAB */
        outb(divisor & 0xff,      iobase+UART_DLL); /* Set speed */
        outb(divisor >> 8,        iobase+UART_DLM);
        outb(lcr,                 iobase+UART_LCR); /* Set 8N1  */
        outb(fcr,                 iobase+UART_FCR); /* Enable FIFO's */

        /* Turn on interrups */
        /* This will generate a fatal interrupt storm.
         * People calling us will do that properly - Jean II */
        //outb(/*UART_IER_RLSI|*/UART_IER_RDI/*|UART_IER_THRI*/, iobase+UART_IER);
}

/*
 * Function __irport_change_speed (instance, state, param)
 *
 *    State machine for changing speed of the device. We do it this way since
 *    we cannot use schedule_timeout() when we are in interrupt context
 *
 */
int __irport_change_speed(struct irda_task *task)
{
        struct irport_cb *self;
        __u32 speed = (__u32) task->param;
        unsigned long flags = 0;
        int wasunlocked = 0;
        int ret = 0;

        IRDA_DEBUG(2, "%s(), <%ld>\n", __FUNCTION__, jiffies); 

        self = (struct irport_cb *) task->instance;

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

        /* Locking notes : this function may be called from irq context with
         * spinlock, via irport_write_wakeup(), or from non-interrupt without
         * spinlock (from the task timer). Yuck !
         * This is ugly, and unsafe is the spinlock is not already aquired.
         * This will be fixed when irda-task get rewritten.
         * Jean II */
        if (!spin_is_locked(&self->lock)) {
                spin_lock_irqsave(&self->lock, flags);
                wasunlocked = 1;
        }

        switch (task->state) {
        case IRDA_TASK_INIT:
        case IRDA_TASK_WAIT:
                /* Are we ready to change speed yet? */
                if (self->tx_buff.len > 0) {
                        task->state = IRDA_TASK_WAIT;

                        /* Try again later */
                        ret = msecs_to_jiffies(20);
                        break;
                }

                if (self->dongle)
                        irda_task_next_state(task, IRDA_TASK_CHILD_INIT);
                else
                        irda_task_next_state(task, IRDA_TASK_CHILD_DONE);
                break;
        case IRDA_TASK_CHILD_INIT:
                /* Go to default speed */
                self->change_speed(self->priv, 9600);

                /* Change speed of dongle */
                if (irda_task_execute(self->dongle,
                                      self->dongle->issue->change_speed, 
                                      NULL, task, (void *) speed))
                {
                        /* Dongle need more time to change its speed */
                        irda_task_next_state(task, IRDA_TASK_CHILD_WAIT);

                        /* Give dongle 1 sec to finish */
                        ret = msecs_to_jiffies(1000);
                } else
                        /* Child finished immediately */
                        irda_task_next_state(task, IRDA_TASK_CHILD_DONE);
                break;
        case IRDA_TASK_CHILD_WAIT:
                IRDA_WARNING("%s(), changing speed of dongle timed out!\n", __FUNCTION__);
                ret = -1;               
                break;
        case IRDA_TASK_CHILD_DONE:
                /* Finally we are ready to change the speed */
                self->change_speed(self->priv, speed);
                
                irda_task_next_state(task, IRDA_TASK_DONE);
                break;
        default:
                IRDA_ERROR("%s(), unknown state %d\n",
                           __FUNCTION__, task->state);
                irda_task_next_state(task, IRDA_TASK_DONE);
                ret = -1;
                break;
        }
        /* Put stuff in the state we found them - Jean II */
        if(wasunlocked) {
                spin_unlock_irqrestore(&self->lock, flags);
        }

        return ret;
}

/*
 * Function irport_change_speed_complete (task)
 *
 *    Called when the change speed operation completes
 *
 */
static int irport_change_speed_complete(struct irda_task *task)
{
        struct irport_cb *self;

        IRDA_DEBUG(1, "%s()\n", __FUNCTION__);

        self = (struct irport_cb *) task->instance;

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

        /* Finished changing speed, so we are not busy any longer */
        /* Signal network layer so it can try to send the frame */

        netif_wake_queue(self->netdev);
        
        return 0;
}

/*
 * Function irport_timeout (struct net_device *dev)
 *
 *    The networking layer thinks we timed out.
 *
 */

static void irport_timeout(struct net_device *dev)
{
        struct irport_cb *self;
        int iobase;
        int iir, lsr;
        unsigned long flags;

        self = (struct irport_cb *) dev->priv;
        IRDA_ASSERT(self != NULL, return;);
        iobase = self->io.sir_base;
        
        IRDA_WARNING("%s: transmit timed out, jiffies = %ld, trans_start = %ld\n",
                dev->name, jiffies, dev->trans_start);
        spin_lock_irqsave(&self->lock, flags);

        /* Debug what's happening... */

        /* Get interrupt status */
        lsr = inb(iobase+UART_LSR);
        /* Read interrupt register */
        iir = inb(iobase+UART_IIR);
        IRDA_DEBUG(0, "%s(), iir=%02x, lsr=%02x, iobase=%#x\n", 
                   __FUNCTION__, iir, lsr, iobase);

        IRDA_DEBUG(0, "%s(), transmitting=%d, remain=%d, done=%d\n", 
                   __FUNCTION__, self->transmitting, self->tx_buff.len,
                   self->tx_buff.data - self->tx_buff.head);

        /* Now, restart the port */
        irport_start(self);
        self->change_speed(self->priv, self->io.speed);
        /* This will re-enable irqs */
        outb(/*UART_IER_RLSI|*/UART_IER_RDI/*|UART_IER_THRI*/, iobase+UART_IER);
        dev->trans_start = jiffies;
        spin_unlock_irqrestore(&self->lock, flags);

        netif_wake_queue(dev);
}
 
/*
 * Function irport_wait_hw_transmitter_finish ()
 *
 *    Wait for the real end of HW transmission
 *
 * The UART is a strict FIFO, and we get called only when we have finished
 * pushing data to the FIFO, so the maximum amount of time we must wait
 * is only for the FIFO to drain out.
 *
 * We use a simple calibrated loop. We may need to adjust the loop
 * delay (udelay) to balance I/O traffic and latency. And we also need to
 * adjust the maximum timeout.
 * It would probably be better to wait for the proper interrupt,
 * but it doesn't seem to be available.
 *
 * We can't use jiffies or kernel timers because :
 * 1) We are called from the interrupt handler, which disable softirqs,
 * so jiffies won't be increased
 * 2) Jiffies granularity is usually very coarse (10ms), and we don't
 * want to wait that long to detect stuck hardware.
 * Jean II
 */

static void irport_wait_hw_transmitter_finish(struct irport_cb *self)
{
        int iobase;
        int count = 1000;       /* 1 ms */
        
        iobase = self->io.sir_base;

        /* Calibrated busy loop */
        while((count-- > 0) && !(inb(iobase+UART_LSR) & UART_LSR_TEMT))
                udelay(1);

        if(count == 0)
                IRDA_DEBUG(0, "%s(): stuck transmitter\n", __FUNCTION__);
}

/*
 * Function irport_hard_start_xmit (struct sk_buff *skb, struct net_device *dev)
 *
 *    Transmits the current frame until FIFO is full, then
 *    waits until the next transmitt interrupt, and continues until the
 *    frame is transmitted.
 */
static int irport_hard_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct irport_cb *self;
        unsigned long flags;
        int iobase;
        s32 speed;

        IRDA_DEBUG(1, "%s()\n", __FUNCTION__);

        IRDA_ASSERT(dev != NULL, return 0;);
        
        self = (struct irport_cb *) dev->priv;
        IRDA_ASSERT(self != NULL, return 0;);

        iobase = self->io.sir_base;

        netif_stop_queue(dev);

        /* Make sure tests & speed change are atomic */
        spin_lock_irqsave(&self->lock, flags);

        /* Check if we need to change the speed */
        speed = irda_get_next_speed(skb);
        if ((speed != self->io.speed) && (speed != -1)) {
                /* Check for empty frame */
                if (!skb->len) {
                        /*
                         * We send frames one by one in SIR mode (no
                         * pipelining), so at this point, if we were sending
                         * a previous frame, we just received the interrupt
                         * telling us it is finished (UART_IIR_THRI).
                         * Therefore, waiting for the transmitter to really
                         * finish draining the fifo won't take too long.
                         * And the interrupt handler is not expected to run.
                         * - Jean II */
                        irport_wait_hw_transmitter_finish(self);
                        /* Better go there already locked - Jean II */
                        irda_task_execute(self, __irport_change_speed, 
                                          irport_change_speed_complete, 
                                          NULL, (void *) speed);
                        dev->trans_start = jiffies;
                        spin_unlock_irqrestore(&self->lock, flags);
                        dev_kfree_skb(skb);
                        return 0;
                } else
                        self->new_speed = speed;
        }

        /* Init tx buffer */
        self->tx_buff.data = self->tx_buff.head;

        /* Copy skb to tx_buff while wrapping, stuffing and making CRC */
        self->tx_buff.len = async_wrap_skb(skb, self->tx_buff.data, 
                                           self->tx_buff.truesize);
        
        self->stats.tx_bytes += self->tx_buff.len;

        /* We are transmitting */
        self->transmitting = 1;

        /* Turn on transmit finished interrupt. Will fire immediately!  */
        outb(UART_IER_THRI, iobase+UART_IER); 

        dev->trans_start = jiffies;
        spin_unlock_irqrestore(&self->lock, flags);

        dev_kfree_skb(skb);
        
        return 0;
}
        
/*
 * Function irport_write (driver)
 *
 *    Fill Tx FIFO with transmit data
 *
 * Called only from irport_write_wakeup()
 */
static inline int irport_write(int iobase, int fifo_size, __u8 *buf, int len)
{
        int actual = 0;

        /* Fill FIFO with current frame */
        while ((actual < fifo_size) && (actual < len)) {
                /* Transmit next byte */
                outb(buf[actual], iobase+UART_TX);

                actual++;
        }
        
        return actual;
}

/*
 * Function irport_write_wakeup (tty)
 *
 *    Called by the driver when there's room for more data.  If we have
 *    more packets to send, we send them here.
 *
 * Called only from irport_interrupt()
 * Make sure this function is *not* called while we are receiving,
 * otherwise we will reset fifo and loose data :-(
 */
static inline void irport_write_wakeup(struct irport_cb *self)
{
        int actual = 0;
        int iobase;
        unsigned int fcr;

        IRDA_ASSERT(self != NULL, return;);

        IRDA_DEBUG(4, "%s()\n", __FUNCTION__);

        iobase = self->io.sir_base;

        /* Finished with frame?  */
        if (self->tx_buff.len > 0)  {
                /* Write data left in transmit buffer */
                actual = irport_write(iobase, self->io.fifo_size, 
                                      self->tx_buff.data, self->tx_buff.len);
                self->tx_buff.data += actual;
                self->tx_buff.len  -= actual;
        } else {
                /* 
                 *  Now serial buffer is almost free & we can start 
                 *  transmission of another packet. But first we must check
                 *  if we need to change the speed of the hardware
                 */
                if (self->new_speed) {
                        irport_wait_hw_transmitter_finish(self);
                        irda_task_execute(self, __irport_change_speed, 
                                          irport_change_speed_complete, 
                                          NULL, (void *) self->new_speed);
                        self->new_speed = 0;
                } else {
                        /* Tell network layer that we want more frames */
                        netif_wake_queue(self->netdev);
                }
                self->stats.tx_packets++;

                /* 
                 * Reset Rx FIFO to make sure that all reflected transmit data
                 * is discarded. This is needed for half duplex operation
                 */
                fcr = irport_get_fcr(self->io.speed);
                fcr |= UART_FCR_CLEAR_RCVR;
                outb(fcr, iobase+UART_FCR);

                /* Finished transmitting */
                self->transmitting = 0;

                /* Turn on receive interrupts */
                outb(UART_IER_RDI, iobase+UART_IER);

                IRDA_DEBUG(1, "%s() : finished Tx\n", __FUNCTION__);
        }
}

/*
 * Function irport_receive (self)
 *
 *    Receive one frame from the infrared port
 *
 * Called only from irport_interrupt()
 */
static inline void irport_receive(struct irport_cb *self) 
{
        int boguscount = 0;
        int iobase;

        IRDA_ASSERT(self != NULL, return;);

        iobase = self->io.sir_base;

        /*  
         * Receive all characters in Rx FIFO, unwrap and unstuff them. 
         * async_unwrap_char will deliver all found frames  
         */
        do {
                async_unwrap_char(self->netdev, &self->stats, &self->rx_buff, 
                                  inb(iobase+UART_RX));

                /* Make sure we don't stay here too long */
                if (boguscount++ > 32) {
                        IRDA_DEBUG(2,"%s(), breaking!\n", __FUNCTION__);
                        break;
                }
        } while (inb(iobase+UART_LSR) & UART_LSR_DR);   
}

/*
 * Function irport_interrupt (irq, dev_id, regs)
 *
 *    Interrupt handler
 */
static irqreturn_t irport_interrupt(int irq, void *dev_id,
                                    struct pt_regs *regs) 
{
        struct net_device *dev = (struct net_device *) dev_id;
        struct irport_cb *self;
        int boguscount = 0;
        int iobase;
        int iir, lsr;
        int handled = 0;

        if (!dev) {
                IRDA_WARNING("%s() irq %d for unknown device.\n", __FUNCTION__, irq);
                return IRQ_NONE;
        }
        self = (struct irport_cb *) dev->priv;

        spin_lock(&self->lock);

        iobase = self->io.sir_base;

        /* Cut'n'paste interrupt routine from serial.c
         * This version try to minimise latency and I/O operations.
         * Simplified and modified to enforce half duplex operation.
         * - Jean II */

        /* Check status even is iir reg is cleared, more robust and
         * eliminate a read on the I/O bus - Jean II */
        do {
                /* Get interrupt status ; Clear interrupt */
                lsr = inb(iobase+UART_LSR);
                
                /* Are we receiving or transmitting ? */
                if(!self->transmitting) {
                        /* Received something ? */
                        if (lsr & UART_LSR_DR)
                                irport_receive(self);
                } else {
                        /* Room in Tx fifo ? */
                        if (lsr & (UART_LSR_THRE | UART_LSR_TEMT))
                                irport_write_wakeup(self);
                }

                /* A bit hackish, but working as expected... Jean II */
                if(lsr & (UART_LSR_THRE | UART_LSR_TEMT | UART_LSR_DR))
                        handled = 1;

                /* Make sure we don't stay here to long */
                if (boguscount++ > 10) {
                        IRDA_WARNING("%s() irq handler looping : lsr=%02x\n",
                                     __FUNCTION__, lsr);
                        break;
                }

                /* Read interrupt register */
                iir = inb(iobase+UART_IIR);

                /* Enable this debug only when no other options and at low
                 * bit rates, otherwise it may cause Rx overruns (lsr=63).
                 * - Jean II */
                IRDA_DEBUG(6, "%s(), iir=%02x, lsr=%02x, iobase=%#x\n", 
                            __FUNCTION__, iir, lsr, iobase);

                /* As long as interrupt pending... */
        } while ((iir & UART_IIR_NO_INT) == 0);

        spin_unlock(&self->lock);
        return IRQ_RETVAL(handled);
}

/*
 * Function irport_net_open (dev)
 *
 *    Network device is taken up. Usually this is done by "ifconfig irda0 up" 
 *   
 */
static int irport_net_open(struct net_device *dev)
{
        struct irport_cb *self;
        int iobase;
        char hwname[16];
        unsigned long flags;

        IRDA_DEBUG(2, "%s()\n", __FUNCTION__);

        IRDA_ASSERT(dev != NULL, return -1;);
        self = (struct irport_cb *) dev->priv;

        iobase = self->io.sir_base;

        if (request_irq(self->io.irq, self->interrupt, 0, dev->name, 
                        (void *) dev)) {
                IRDA_DEBUG(0, "%s(), unable to allocate irq=%d\n",
                           __FUNCTION__, self->io.irq);
                return -EAGAIN;
        }

        spin_lock_irqsave(&self->lock, flags);
        /* Init uart */
        irport_start(self);
        /* Set 9600 bauds per default, including at the dongle */
        irda_task_execute(self, __irport_change_speed, 
                          irport_change_speed_complete, 
                          NULL, (void *) 9600);
        spin_unlock_irqrestore(&self->lock, flags);


        /* Give self a hardware name */
        sprintf(hwname, "SIR @ 0x%03x", self->io.sir_base);

        /* 
         * Open new IrLAP layer instance, now that everything should be
         * initialized properly 
         */
        self->irlap = irlap_open(dev, &self->qos, hwname);

        /* Ready to play! */

        netif_start_queue(dev);

        return 0;
}

/*
 * Function irport_net_close (self)
 *
 *    Network device is taken down. Usually this is done by 
 *    "ifconfig irda0 down" 
 */
static int irport_net_close(struct net_device *dev)
{
        struct irport_cb *self;
        int iobase;
        unsigned long flags;

        IRDA_DEBUG(4, "%s()\n", __FUNCTION__);

        IRDA_ASSERT(dev != NULL, return -1;);
        self = (struct irport_cb *) dev->priv;

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

        iobase = self->io.sir_base;

        /* Stop device */
        netif_stop_queue(dev);
        
        /* Stop and remove instance of IrLAP */
        if (self->irlap)
                irlap_close(self->irlap);
        self->irlap = NULL;

        spin_lock_irqsave(&self->lock, flags);
        irport_stop(self);
        spin_unlock_irqrestore(&self->lock, flags);

        free_irq(self->io.irq, dev);

        return 0;
}

/*
 * Function irport_is_receiving (self)
 *
 *    Returns true is we are currently receiving data
 *
 */
static inline int irport_is_receiving(struct irport_cb *self)
{
        return (self->rx_buff.state != OUTSIDE_FRAME);
}

/*
 * Function irport_set_dtr_rts (tty, dtr, rts)
 *
 *    This function can be used by dongles etc. to set or reset the status
 *    of the dtr and rts lines
 */
static int irport_set_dtr_rts(struct net_device *dev, int dtr, int rts)
{
        struct irport_cb *self = dev->priv;
        int iobase;

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

        iobase = self->io.sir_base;

        if (dtr)
                dtr = UART_MCR_DTR;
        if (rts)
                rts = UART_MCR_RTS;

        outb(dtr|rts|UART_MCR_OUT2, iobase+UART_MCR);

        return 0;
}

static int irport_raw_write(struct net_device *dev, __u8 *buf, int len)
{
        struct irport_cb *self = (struct irport_cb *) dev->priv;
        int actual = 0;
        int iobase;

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

        iobase = self->io.sir_base;

        /* Tx FIFO should be empty! */
        if (!(inb(iobase+UART_LSR) & UART_LSR_THRE)) {
                IRDA_DEBUG( 0, "%s(), failed, fifo not empty!\n", __FUNCTION__);
                return -1;
        }
        
        /* Fill FIFO with current frame */
        while (actual < len) {
                /* Transmit next byte */
                outb(buf[actual], iobase+UART_TX);
                actual++;
        }

        return actual;
}

/*
 * Function irport_net_ioctl (dev, rq, cmd)
 *
 *    Process IOCTL commands for this device
 *
 */
static int irport_net_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
{
        struct if_irda_req *irq = (struct if_irda_req *) rq;
        struct irport_cb *self;
        dongle_t *dongle;
        unsigned long flags;
        int ret = 0;

        IRDA_ASSERT(dev != NULL, return -1;);

        self = dev->priv;

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

        IRDA_DEBUG(2, "%s(), %s, (cmd=0x%X)\n", __FUNCTION__, dev->name, cmd);
        
        switch (cmd) {
        case SIOCSBANDWIDTH: /* Set bandwidth */
                if (!capable(CAP_NET_ADMIN))
                        ret = -EPERM;
                else
                        irda_task_execute(self, __irport_change_speed, NULL, 
                                          NULL, (void *) irq->ifr_baudrate);
                break;
        case SIOCSDONGLE: /* Set dongle */
                if (!capable(CAP_NET_ADMIN)) {
                        ret = -EPERM;
                        break;
                }

                /* Locking :
                 * irda_device_dongle_init() can't be locked.
                 * irda_task_execute() doesn't need to be locked.
                 * Jean II
                 */

                /* Initialize dongle */
                dongle = irda_device_dongle_init(dev, irq->ifr_dongle);
                if (!dongle)
                        break;
                
                dongle->set_mode    = NULL;
                dongle->read        = NULL;
                dongle->write       = irport_raw_write;
                dongle->set_dtr_rts = irport_set_dtr_rts;
                
                /* Now initialize the dongle!  */
                dongle->issue->open(dongle, &self->qos);
                
                /* Reset dongle */
                irda_task_execute(dongle, dongle->issue->reset, NULL, NULL, 
                                  NULL);        

                /* Make dongle available to driver only now to avoid
                 * race conditions - Jean II */
                self->dongle = dongle;
                break;
        case SIOCSMEDIABUSY: /* Set media busy */
                if (!capable(CAP_NET_ADMIN)) {
                        ret = -EPERM;
                        break;
                }

                irda_device_set_media_busy(self->netdev, TRUE);
                break;
        case SIOCGRECEIVING: /* Check if we are receiving right now */
                irq->ifr_receiving = irport_is_receiving(self);
                break;
        case SIOCSDTRRTS:
                if (!capable(CAP_NET_ADMIN)) {
                        ret = -EPERM;
                        break;
                }

                /* No real need to lock... */
                spin_lock_irqsave(&self->lock, flags);
                irport_set_dtr_rts(dev, irq->ifr_dtr, irq->ifr_rts);
                spin_unlock_irqrestore(&self->lock, flags);
                break;
        default:
                ret = -EOPNOTSUPP;
        }
        
        return ret;
}

static struct net_device_stats *irport_net_get_stats(struct net_device *dev)
{
        struct irport_cb *self = (struct irport_cb *) dev->priv;
        
        return &self->stats;
}

static int __init irport_init(void)
{
        int i;

        for (i=0; (io[i] < 2000) && (i < 4); i++) {
                if (irport_open(i, io[i], irq[i]) != NULL)
                        return 0;
        }
        /* 
         * Maybe something failed, but we can still be usable for FIR drivers 
         */
        return 0;
}

/*
 * Function irport_cleanup ()
 *
 *    Close all configured ports
 *
 */
static void __exit irport_cleanup(void)
{
        int i;

        IRDA_DEBUG( 4, "%s()\n", __FUNCTION__);

        for (i=0; i < 4; i++) {
                if (dev_self[i])
                        irport_close(dev_self[i]);
        }
}

MODULE_PARM(io, "1-4i");
MODULE_PARM_DESC(io, "Base I/O addresses");
MODULE_PARM(irq, "1-4i");
MODULE_PARM_DESC(irq, "IRQ lines");

MODULE_AUTHOR("Dag Brattli <dagb@cs.uit.no>");
MODULE_DESCRIPTION("Half duplex serial driver for IrDA SIR mode");
MODULE_LICENSE("GPL");

module_init(irport_init);
module_exit(irport_cleanup);