sir_dev.c

《linux驱动程序设计从入门到精通》一书中所有的程序代码含驱动和相应的应用程序

/*********************************************************************
 *
 *	sir_dev.c:	irda sir network device
 * 
 *	Copyright (c) 2002 Martin Diehl
 * 
 *	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.
 *
 ********************************************************************/    

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/delay.h>

#include <net/irda/irda.h>
#include <net/irda/wrapper.h>
#include <net/irda/irda_device.h>

#include "sir-dev.h"


static struct workqueue_struct *irda_sir_wq;

/* STATE MACHINE */

/* substate handler of the config-fsm to handle the cases where we want
 * to wait for transmit completion before changing the port configuration
 */

static int sirdev_tx_complete_fsm(struct sir_dev *dev)
{
	struct sir_fsm *fsm = &dev->fsm;
	unsigned next_state, delay;
	unsigned bytes_left;

	do {
		next_state = fsm->substate;	/* default: stay in current substate */
		delay = 0;

		switch(fsm->substate) {

		case SIRDEV_STATE_WAIT_XMIT:
			if (dev->drv->chars_in_buffer)
				bytes_left = dev->drv->chars_in_buffer(dev);
			else
				bytes_left = 0;
			if (!bytes_left) {
				next_state = SIRDEV_STATE_WAIT_UNTIL_SENT;
				break;
			}

			if (dev->speed > 115200)
				delay = (bytes_left*8*10000) / (dev->speed/100);
			else if (dev->speed > 0)
				delay = (bytes_left*10*10000) / (dev->speed/100);
			else
				delay = 0;
			/* expected delay (usec) until remaining bytes are sent */
			if (delay < 100) {
				udelay(delay);
				delay = 0;
				break;
			}
			/* sleep some longer delay (msec) */
			delay = (delay+999) / 1000;
			break;

		case SIRDEV_STATE_WAIT_UNTIL_SENT:
			/* block until underlaying hardware buffer are empty */
			if (dev->drv->wait_until_sent)
				dev->drv->wait_until_sent(dev);
			next_state = SIRDEV_STATE_TX_DONE;
			break;

		case SIRDEV_STATE_TX_DONE:
			return 0;

		default:
			IRDA_ERROR("%s - undefined state\n", __FUNCTION__);
			return -EINVAL;
		}
		fsm->substate = next_state;
	} while (delay == 0);
	return delay;
}

/*
 * Function sirdev_config_fsm
 *
 * State machine to handle the configuration of the device (and attached dongle, if any).
 * This handler is scheduled for execution in kIrDAd context, so we can sleep.
 * however, kIrDAd is shared by all sir_dev devices so we better don't sleep there too
 * long. Instead, for longer delays we start a timer to reschedule us later.
 * On entry, fsm->sem is always locked and the netdev xmit queue stopped.
 * Both must be unlocked/restarted on completion - but only on final exit.
 */

static void sirdev_config_fsm(struct work_struct *work)
{
	struct sir_dev *dev = container_of(work, struct sir_dev, fsm.work.work);
	struct sir_fsm *fsm = &dev->fsm;
	int next_state;
	int ret = -1;
	unsigned delay;

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

	do {
		IRDA_DEBUG(3, "%s - state=0x%04x / substate=0x%04x\n",
			__FUNCTION__, fsm->state, fsm->substate);

		next_state = fsm->state;
		delay = 0;

		switch(fsm->state) {

		case SIRDEV_STATE_DONGLE_OPEN:
			if (dev->dongle_drv != NULL) {
				ret = sirdev_put_dongle(dev);
				if (ret) {
					fsm->result = -EINVAL;
					next_state = SIRDEV_STATE_ERROR;
					break;
				}
			}

			/* Initialize dongle */
			ret = sirdev_get_dongle(dev, fsm->param);
			if (ret) {
				fsm->result = ret;
				next_state = SIRDEV_STATE_ERROR;
				break;
			}

			/* Dongles are powered through the modem control lines which
			 * were just set during open. Before resetting, let's wait for
			 * the power to stabilize. This is what some dongle drivers did
			 * in open before, while others didn't - should be safe anyway.
			 */

			delay = 50;
			fsm->substate = SIRDEV_STATE_DONGLE_RESET;
			next_state = SIRDEV_STATE_DONGLE_RESET;

			fsm->param = 9600;

			break;

		case SIRDEV_STATE_DONGLE_CLOSE:
			/* shouldn't we just treat this as success=? */
			if (dev->dongle_drv == NULL) {
				fsm->result = -EINVAL;
				next_state = SIRDEV_STATE_ERROR;
				break;
			}

			ret = sirdev_put_dongle(dev);
			if (ret) {
				fsm->result = ret;
				next_state = SIRDEV_STATE_ERROR;
				break;
			}
			next_state = SIRDEV_STATE_DONE;
			break;

		case SIRDEV_STATE_SET_DTR_RTS:
			ret = sirdev_set_dtr_rts(dev,
				(fsm->param&0x02) ? TRUE : FALSE,
				(fsm->param&0x01) ? TRUE : FALSE);
			next_state = SIRDEV_STATE_DONE;
			break;

		case SIRDEV_STATE_SET_SPEED:
			fsm->substate = SIRDEV_STATE_WAIT_XMIT;
			next_state = SIRDEV_STATE_DONGLE_CHECK;
			break;

		case SIRDEV_STATE_DONGLE_CHECK:
			ret = sirdev_tx_complete_fsm(dev);
			if (ret < 0) {
				fsm->result = ret;
				next_state = SIRDEV_STATE_ERROR;
				break;
			}
			if ((delay=ret) != 0)
				break;

			if (dev->dongle_drv) {
				fsm->substate = SIRDEV_STATE_DONGLE_RESET;
				next_state = SIRDEV_STATE_DONGLE_RESET;
			}
			else {
				dev->speed = fsm->param;
				next_state = SIRDEV_STATE_PORT_SPEED;
			}
			break;

		case SIRDEV_STATE_DONGLE_RESET:
			if (dev->dongle_drv->reset) {
				ret = dev->dongle_drv->reset(dev);
				if (ret < 0) {
					fsm->result = ret;
					next_state = SIRDEV_STATE_ERROR;
					break;
				}
			}
			else
				ret = 0;
			if ((delay=ret) == 0) {
				/* set serial port according to dongle default speed */
				if (dev->drv->set_speed)
					dev->drv->set_speed(dev, dev->speed);
				fsm->substate = SIRDEV_STATE_DONGLE_SPEED;
				next_state = SIRDEV_STATE_DONGLE_SPEED;
			}
			break;

		case SIRDEV_STATE_DONGLE_SPEED:
			if (dev->dongle_drv->reset) {
				ret = dev->dongle_drv->set_speed(dev, fsm->param);
				if (ret < 0) {
					fsm->result = ret;
					next_state = SIRDEV_STATE_ERROR;
					break;
				}
			}
			else
				ret = 0;
			if ((delay=ret) == 0)
				next_state = SIRDEV_STATE_PORT_SPEED;
			break;

		case SIRDEV_STATE_PORT_SPEED:
			/* Finally we are ready to change the serial port speed */
			if (dev->drv->set_speed)
				dev->drv->set_speed(dev, dev->speed);
			dev->new_speed = 0;
			next_state = SIRDEV_STATE_DONE;
			break;

		case SIRDEV_STATE_DONE:
			/* Signal network layer so it can send more frames */
			netif_wake_queue(dev->netdev);
			next_state = SIRDEV_STATE_COMPLETE;
			break;

		default:
			IRDA_ERROR("%s - undefined state\n", __FUNCTION__);
			fsm->result = -EINVAL;
			/* fall thru */

		case SIRDEV_STATE_ERROR:
			IRDA_ERROR("%s - error: %d\n", __FUNCTION__, fsm->result);

#if 0	/* don't enable this before we have netdev->tx_timeout to recover */
			netif_stop_queue(dev->netdev);
#else
			netif_wake_queue(dev->netdev);
#endif
			/* fall thru */

		case SIRDEV_STATE_COMPLETE:
			/* config change finished, so we are not busy any longer */
			sirdev_enable_rx(dev);
			up(&fsm->sem);
			return;
		}
		fsm->state = next_state;
	} while(!delay);

	queue_delayed_work(irda_sir_wq, &fsm->work, msecs_to_jiffies(delay));
}

/* schedule some device configuration task for execution by kIrDAd
 * on behalf of the above state machine.
 * can be called from process or interrupt/tasklet context.
 */

int sirdev_schedule_request(struct sir_dev *dev, int initial_state, unsigned param)
{
	struct sir_fsm *fsm = &dev->fsm;

	IRDA_DEBUG(2, "%s - state=0x%04x / param=%u\n", __FUNCTION__, initial_state, param);

	if (down_trylock(&fsm->sem)) {
		if (in_interrupt()  ||  in_atomic()  ||  irqs_disabled()) {
			IRDA_DEBUG(1, "%s(), state machine busy!\n", __FUNCTION__);
			return -EWOULDBLOCK;
		} else
			down(&fsm->sem);
	}

	if (fsm->state == SIRDEV_STATE_DEAD) {
		/* race with sirdev_close should never happen */
		IRDA_ERROR("%s(), instance staled!\n", __FUNCTION__);
		up(&fsm->sem);
		return -ESTALE;		/* or better EPIPE? */
	}

	netif_stop_queue(dev->netdev);
	atomic_set(&dev->enable_rx, 0);

	fsm->state = initial_state;
	fsm->param = param;
	fsm->result = 0;

	INIT_DELAYED_WORK(&fsm->work, sirdev_config_fsm);
	queue_delayed_work(irda_sir_wq, &fsm->work, 0);
	return 0;
}


/***************************************************************************/

void sirdev_enable_rx(struct sir_dev *dev)
{
	if (unlikely(atomic_read(&dev->enable_rx)))
		return;

	/* flush rx-buffer - should also help in case of problems with echo cancelation */
	dev->rx_buff.data = dev->rx_buff.head;
	dev->rx_buff.len = 0;
	dev->rx_buff.in_frame = FALSE;
	dev->rx_buff.state = OUTSIDE_FRAME;
	atomic_set(&dev->enable_rx, 1);
}

static int sirdev_is_receiving(struct sir_dev *dev)
{
	if (!atomic_read(&dev->enable_rx))
		return 0;

	return (dev->rx_buff.state != OUTSIDE_FRAME);
}

int sirdev_set_dongle(struct sir_dev *dev, IRDA_DONGLE type)
{
	int err;

	IRDA_DEBUG(3, "%s : requesting dongle %d.\n", __FUNCTION__, type);

	err = sirdev_schedule_dongle_open(dev, type);
	if (unlikely(err))
		return err;
	down(&dev->fsm.sem);		/* block until config change completed */
	err = dev->fsm.result;
	up(&dev->fsm.sem);
	return err;
}
EXPORT_SYMBOL(sirdev_set_dongle);

/* used by dongle drivers for dongle programming */

int sirdev_raw_write(struct sir_dev *dev, const char *buf, int len)
{
	unsigned long flags;
	int ret;

	if (unlikely(len > dev->tx_buff.truesize))
		return -ENOSPC;

	spin_lock_irqsave(&dev->tx_lock, flags);	/* serialize with other tx operations */
	while (dev->tx_buff.len > 0) {			/* wait until tx idle */
		spin_unlock_irqrestore(&dev->tx_lock, flags);
		msleep(10);
		spin_lock_irqsave(&dev->tx_lock, flags);
	}

	dev->tx_buff.data = dev->tx_buff.head;
	memcpy(dev->tx_buff.data, buf, len);	
	dev->tx_buff.len = len;

	ret = dev->drv->do_write(dev, dev->tx_buff.data, dev->tx_buff.len);
	if (ret > 0) {
		IRDA_DEBUG(3, "%s(), raw-tx started\n", __FUNCTION__);

		dev->tx_buff.data += ret;
		dev->tx_buff.len -= ret;
		dev->raw_tx = 1;
		ret = len;		/* all data is going to be sent */
	}
	spin_unlock_irqrestore(&dev->tx_lock, flags);
	return ret;
}
EXPORT_SYMBOL(sirdev_raw_write);

/* seems some dongle drivers may need this */

int sirdev_raw_read(struct sir_dev *dev, char *buf, int len)
{
	int count;

	if (atomic_read(&dev->enable_rx))
		return -EIO;		/* fail if we expect irda-frames */

	count = (len < dev->rx_buff.len) ? len : dev->rx_buff.len;

	if (count > 0) {
		memcpy(buf, dev->rx_buff.data, count);
		dev->rx_buff.data += count;
		dev->rx_buff.len -= count;
	}

	/* remaining stuff gets flushed when re-enabling normal rx */

	return count;
}
EXPORT_SYMBOL(sirdev_raw_read);

int sirdev_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
{
	int ret = -ENXIO;
	if (dev->drv->set_dtr_rts != 0)
		ret =  dev->drv->set_dtr_rts(dev, dtr, rts);
	return ret;
}
EXPORT_SYMBOL(sirdev_set_dtr_rts);

/**********************************************************************/

/* called from client driver - likely with bh-context - to indicate
 * it made some progress with transmission. Hence we send the next
 * chunk, if any, or complete the skb otherwise
 */

void sirdev_write_complete(struct sir_dev *dev)
{
	unsigned long flags;
	struct sk_buff *skb;
	int actual = 0;
	int err;
	
	spin_lock_irqsave(&dev->tx_lock, flags);

	IRDA_DEBUG(3, "%s() - dev->tx_buff.len = %d\n",
		   __FUNCTION__, dev->tx_buff.len);

	if (likely(dev->tx_buff.len > 0))  {
		/* Write data left in transmit buffer */
		actual = dev->drv->do_write(dev, dev->tx_buff.data, dev->tx_buff.len);

		if (likely(actual>0)) {
			dev->tx_buff.data += actual;
			dev->tx_buff.len  -= actual;
		}
		else if (unlikely(actual<0)) {
			/* could be dropped later when we have tx_timeout to recover */
			IRDA_ERROR("%s: drv->do_write failed (%d)\n",
				   __FUNCTION__, actual);
			if ((skb=dev->tx_skb) != NULL) {
				dev->tx_skb = NULL;
				dev_kfree_skb_any(skb);
				dev->stats.tx_errors++;		      
				dev->stats.tx_dropped++;		      
			}
			dev->tx_buff.len = 0;
		}
		if (dev->tx_buff.len > 0)
			goto done;	/* more data to send later */
	}

	if (unlikely(dev->raw_tx != 0)) {
		/* in raw mode we are just done now after the buffer was sent
		 * completely. Since this was requested by some dongle driver
		 * running under the control of the irda-thread we must take
		 * care here not to re-enable the queue. The queue will be
		 * restarted when the irda-thread has completed the request.
		 */

		IRDA_DEBUG(3, "%s(), raw-tx done\n", __FUNCTION__);
		dev->raw_tx = 0;
		goto done;	/* no post-frame handling in raw mode */
	}

	/* we have finished now sending this skb.
	 * update statistics and free the skb.
	 * finally we check and trigger a pending speed change, if any.
	 * if not we switch to rx mode and wake the queue for further
	 * packets.
	 * note the scheduled speed request blocks until the lower
	 * client driver and the corresponding hardware has really
	 * finished sending all data (xmit fifo drained f.e.)
	 * before the speed change gets finally done and the queue
	 * re-activated.
	 */

	IRDA_DEBUG(5, "%s(), finished with frame!\n", __FUNCTION__);
		
	if ((skb=dev->tx_skb) != NULL) {
		dev->tx_skb = NULL;
		dev->stats.tx_packets++;