static ssize_t ac_write()

in applicom.c [353:479]

• 95 lines of code
• 17 McCabe index (conditional complexity)

static ssize_t ac_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
	unsigned int NumCard;	/* Board number 1 -> 8           */
	unsigned int IndexCard;	/* Index board number 0 -> 7     */
	unsigned char TicCard;	/* Board TIC to send             */
	unsigned long flags;	/* Current priority              */
	struct st_ram_io st_loc;
	struct mailbox tmpmailbox;
#ifdef DEBUG
	int c;
#endif
	DECLARE_WAITQUEUE(wait, current);

	if (count != sizeof(struct st_ram_io) + sizeof(struct mailbox)) {
		static int warncount = 5;
		if (warncount) {
			printk(KERN_INFO "Hmmm. write() of Applicom card, length %zd != expected %zd\n",
			       count, sizeof(struct st_ram_io) + sizeof(struct mailbox));
			warncount--;
		}
		return -EINVAL;
	}

	if(copy_from_user(&st_loc, buf, sizeof(struct st_ram_io))) 
		return -EFAULT;
	
	if(copy_from_user(&tmpmailbox, &buf[sizeof(struct st_ram_io)],
			  sizeof(struct mailbox))) 
		return -EFAULT;

	NumCard = st_loc.num_card;	/* board number to send          */
	TicCard = st_loc.tic_des_from_pc;	/* tic number to send            */
	IndexCard = NumCard - 1;

	if (IndexCard >= MAX_BOARD)
		return -EINVAL;
	IndexCard = array_index_nospec(IndexCard, MAX_BOARD);

	if (!apbs[IndexCard].RamIO)
		return -EINVAL;

#ifdef DEBUG
	printk("Write to applicom card #%d. struct st_ram_io follows:",
	       IndexCard+1);

		for (c = 0; c < sizeof(struct st_ram_io);) {
		
			printk("\n%5.5X: %2.2X", c, ((unsigned char *) &st_loc)[c]);

			for (c++; c % 8 && c < sizeof(struct st_ram_io); c++) {
				printk(" %2.2X", ((unsigned char *) &st_loc)[c]);
			}
		}

		printk("\nstruct mailbox follows:");

		for (c = 0; c < sizeof(struct mailbox);) {
			printk("\n%5.5X: %2.2X", c, ((unsigned char *) &tmpmailbox)[c]);

			for (c++; c % 8 && c < sizeof(struct mailbox); c++) {
				printk(" %2.2X", ((unsigned char *) &tmpmailbox)[c]);
			}
		}

		printk("\n");
#endif

	spin_lock_irqsave(&apbs[IndexCard].mutex, flags);

	/* Test octet ready correct */
	if(readb(apbs[IndexCard].RamIO + DATA_FROM_PC_READY) > 2) { 
		Dummy = readb(apbs[IndexCard].RamIO + VERS);
		spin_unlock_irqrestore(&apbs[IndexCard].mutex, flags);
		printk(KERN_WARNING "APPLICOM driver write error board %d, DataFromPcReady = %d\n",
		       IndexCard,(int)readb(apbs[IndexCard].RamIO + DATA_FROM_PC_READY));
		DeviceErrorCount++;
		return -EIO;
	}
	
	/* Place ourselves on the wait queue */
	set_current_state(TASK_INTERRUPTIBLE);
	add_wait_queue(&apbs[IndexCard].FlagSleepSend, &wait);

	/* Check whether the card is ready for us */
	while (readb(apbs[IndexCard].RamIO + DATA_FROM_PC_READY) != 0) {
		Dummy = readb(apbs[IndexCard].RamIO + VERS);
		/* It's busy. Sleep. */

		spin_unlock_irqrestore(&apbs[IndexCard].mutex, flags);
		schedule();
		if (signal_pending(current)) {
			remove_wait_queue(&apbs[IndexCard].FlagSleepSend,
					  &wait);
			return -EINTR;
		}
		spin_lock_irqsave(&apbs[IndexCard].mutex, flags);
		set_current_state(TASK_INTERRUPTIBLE);
	}

	/* We may not have actually slept */
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&apbs[IndexCard].FlagSleepSend, &wait);

	writeb(1, apbs[IndexCard].RamIO + DATA_FROM_PC_READY);

	/* Which is best - lock down the pages with rawio and then
	   copy directly, or use bounce buffers? For now we do the latter 
	   because it works with 2.2 still */
	{
		unsigned char *from = (unsigned char *) &tmpmailbox;
		void __iomem *to = apbs[IndexCard].RamIO + RAM_FROM_PC;
		int c;

		for (c = 0; c < sizeof(struct mailbox); c++)
			writeb(*(from++), to++);
	}

	writeb(0x20, apbs[IndexCard].RamIO + TIC_OWNER_FROM_PC);
	writeb(0xff, apbs[IndexCard].RamIO + NUMCARD_OWNER_FROM_PC);
	writeb(TicCard, apbs[IndexCard].RamIO + TIC_DES_FROM_PC);
	writeb(NumCard, apbs[IndexCard].RamIO + NUMCARD_DES_FROM_PC);
	writeb(2, apbs[IndexCard].RamIO + DATA_FROM_PC_READY);
	writeb(1, apbs[IndexCard].RamIO + RAM_IT_FROM_PC);
	Dummy = readb(apbs[IndexCard].RamIO + VERS);
	spin_unlock_irqrestore(&apbs[IndexCard].mutex, flags);
	return 0;
}