lp.c

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/*
 * Generic parallel printer driver
 *
 * Copyright (C) 1992 by Jim Weigand and Linus Torvalds
 * Copyright (C) 1992,1993 by Michael K. Johnson
 * - Thanks much to Gunter Windau for pointing out to me where the error
 *   checking ought to be.
 * Copyright (C) 1993 by Nigel Gamble (added interrupt code)
 * Copyright (C) 1994 by Alan Cox (Modularised it)
 * LPCAREFUL, LPABORT, LPGETSTATUS added by Chris Metcalf, [e-mail]
 * Statistics and support for slow printers by Rob Janssen, [e-mail]
 * "lp=" command line parameters added by Grant Guenther, [e-mail]
 * lp_read (Status readback) support added by Carsten Gross,
 *                                             [e-mail]
 * Support for parport by Philip Blundell <[e-mail]>
 * Parport sharing hacking by Andrea Arcangeli
 * Fixed kernel_(to/from)_user memory copy to check for errors
 * 				by Riccardo Facchetti <[e-mail]>
 * Redesigned interrupt handling for handle printers with buggy handshake
 *				by Andrea Arcangeli, 11 May 1998
 * Full efficient handling of printer with buggy irq handshake (now I have
 * understood the meaning of the strange handshake). This is done sending new
 * characters if the interrupt is just happened, even if the printer say to
 * be still BUSY. This is needed at least with Epson Stylus Color. To enable
 * the new TRUST_IRQ mode read the `LP OPTIMIZATION' section below...
 * Fixed the irq on the rising edge of the strobe case.
 * Obsoleted the CAREFUL flag since a printer that doesn' t work with
 * CAREFUL will block a bit after in lp_check_status().
 *				Andrea Arcangeli, 15 Oct 1998
 */

/* This driver should, in theory, work with any parallel port that has an
 * appropriate low-level driver; all I/O is done through the parport
 * abstraction layer.
 *
 * If this driver is built into the kernel, you can configure it using the
 * kernel command-line.  For example:
 *
 *	lp=parport1,none,parport2	(bind lp0 to parport1, disable lp1 and
 *					 bind lp2 to parport2)
 *
 *	lp=auto				(assign lp devices to all ports that
 *				         have printers attached, as determined
 *					 by the IEEE-1284 autoprobe)
 * 
 *	lp=reset			(reset the printer during 
 *					 initialisation)
 *
 *	lp=off				(disable the printer driver entirely)
 *
 * If the driver is loaded as a module, similar functionality is available
 * using module parameters.  The equivalent of the above commands would be:
 *
 *	# insmod lp.o parport=1,none,2
 *
 *	# insmod lp.o parport=auto
 *
 *	# insmod lp.o reset=1
 */

/*
 * LP OPTIMIZATIONS
 *
 * - TRUST_IRQ flag
 * 
 * Epson Stylus Color, HP and many other new printers want the TRUST_IRQ flag
 * set when printing with interrupts. This is a long story. Such printers
 * use a broken handshake (see the timing graph below) when printing with
 * interrupts. The lp driver as default is just able to handle such bogus
 * handshake, but setting such flag cause lp to go faster and probably do
 * what such printers want (even if not documented).
 *
 * NOTE that setting the TRUST_IRQ flag in some printer can cause the irq
 * printing to fail completly. You must try, to know if your printer
 * will handle it. I suggest a graphics printing to force a major flow of
 * characters to the printer for do the test. NOTE also that the TRUST_IRQ
 * flag _should_ be fine everywhere but there is a lot of buggy hardware out
 * there, so I am forced to implement it as a not-default thing.
 * WARNING: before to do the test, be sure to have not played with the
 * `-w' parameter of tunelp!
 *
 * Note also that lp automagically warn you (with a KERN_WARNING) if it
 * detects that you could _try_ to set the TRUST_IRQ flag to speed up the
 * printing and decrease the CPU load.
 *
 * To set the TRUST_IRQ flag you can use this command:
 *
 * tunelp /dev/lp? -T on
 *
 * If you have an old tunelp executable you can (hack and) use this simple
 * C lazy proggy to set the flag in the lp driver:

-------------------------- cut here -------------------------------------
#include <fcntl.h>
#include <sys/ioctl.h>

#define	LPTRUSTIRQ  0x060f

int main(int argc, char **argv)
{
	int fd = open("/dev/lp0", O_RDONLY);
	ioctl(fd, LPTRUSTIRQ, argc - 1);
	if (argc - 1)
		printf("trusting the irq\n");
	else
		printf("untrusting the irq\n");
	return 0;
}
-------------------------- cut here -------------------------------------

 * - LP_WAIT time
 *
 * You can use this setting if your printer is fast enough and/or your
 * machine is slow enough ;-).
 *
 * tunelp /dev/lp? -w 0
 *
 * - LP_CHAR tries
 *
 * If you print with irqs probably you can decrease the CPU load a lot using
 * this setting. This is not the default because the printing is reported to
 * be jerky somewhere...
 *
 * tunelp /dev/lp? -c 1
 *
 *					11 Nov 1998, Andrea Arcangeli
 */

/* COMPATIBILITY WITH OLD KERNELS
 *
 * Under Linux 2.0 and previous versions, lp devices were bound to ports at
 * particular I/O addresses, as follows:
 *
 *	lp0		0x3bc
 *	lp1		0x378
 *	lp2		0x278
 *
 * The new driver, by default, binds lp devices to parport devices as it
 * finds them.  This means that if you only have one port, it will be bound
 * to lp0 regardless of its I/O address.  If you need the old behaviour, you
 * can force it using the parameters described above.
 */

/*
 * The new interrupt handling code take care of the buggy handshake
 * of some HP and Epson printer:
 * ___
 * ACK    _______________    ___________
 *                       |__|
 * ____
 * BUSY   _________              _______
 *                 |____________|
 *
 * I discovered this using the printer scanner that you can find at:
 *
 *	ftp://e-mind.com/pub/linux/pscan/
 *
 *					11 May 98, Andrea Arcangeli
 *
 * My printer scanner run on an Epson Stylus Color show that such printer
 * generates the irq on the _rising_ edge of the STROBE. Now lp handle
 * this case fine too.
 *
 *					15 Oct 1998, Andrea Arcangeli
 */

#include <linux/module.h>
#include <linux/init.h>

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/sched.h>
#include <linux/malloc.h>
#include <linux/fcntl.h>
#include <linux/delay.h>

#include <linux/parport.h>
#undef LP_STATS
#include <linux/lp.h>

#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/system.h>

/* if you have more than 3 printers, remember to increase LP_NO */
#define LP_NO 3

struct lp_struct lp_table[LP_NO] =
{
	[0 ... LP_NO-1] = {NULL, 0, LP_INIT_CHAR, LP_INIT_TIME, LP_INIT_WAIT,
			   NULL,
#ifdef LP_STATS
			   0, 0, {0},
#endif
			   NULL, 0, 0, 0}
};

/* Test if printer is ready */
#define	LP_READY(status)	((status) & LP_PBUSY)
/* Test if the printer is not acking the strobe */
#define	LP_NO_ACKING(status)	((status) & LP_PACK)
/* Test if the printer has error conditions */
#define LP_NO_ERROR(status)	((status) & LP_PERRORP)

#undef LP_DEBUG
#undef LP_READ_DEBUG

/* --- parport support ----------------------------------------- */

static int lp_preempt(void *handle)
{
       struct lp_struct *lps = (struct lp_struct *)handle;

       if (waitqueue_active (&lps->wait_q))
               wake_up_interruptible(&lps->wait_q);

       /* Don't actually release the port now */
       return 1;
}

#define lp_parport_release(x)	do { parport_release(lp_table[(x)].dev); } while (0);
#define lp_parport_claim(x)	do { parport_claim_or_block(lp_table[(x)].dev); } while (0);

/* --- low-level port access ----------------------------------- */

#define r_dtr(x)	(parport_read_data(lp_table[(x)].dev->port))
#define r_str(x)	(parport_read_status(lp_table[(x)].dev->port))
#define w_ctr(x,y)	do { parport_write_control(lp_table[(x)].dev->port, (y)); } while (0)
#define w_dtr(x,y)	do { parport_write_data(lp_table[(x)].dev->port, (y)); } while (0)

static __inline__ void lp_yield (int minor)
{
	if (!parport_yield_blocking (lp_table[minor].dev))
	{
		if (current->need_resched)
			schedule ();
	} else
		lp_table[minor].irq_missed = 1;
}

static __inline__ void lp_schedule(int minor, long timeout)
{
	struct pardevice *dev = lp_table[minor].dev;
	register unsigned long int timeslip = (jiffies - dev->time);
	if ((timeslip > dev->timeslice) && (dev->port->waithead != NULL)) {
		lp_parport_release(minor);
		lp_table[minor].irq_missed = 1;
		schedule_timeout(timeout);
		lp_parport_claim(minor);
	} 
	else
		schedule_timeout(timeout);
}

static int lp_reset(int minor)
{
	int retval;
	lp_parport_claim (minor);
	w_ctr(minor, LP_PSELECP);
	udelay (LP_DELAY);
	w_ctr(minor, LP_PSELECP | LP_PINITP);
	retval = r_str(minor);
	lp_parport_release (minor);
	return retval;
}

#define	lp_wait(minor)	udelay(LP_WAIT(minor))

static inline int lp_char(char lpchar, int minor)
{
	unsigned long count = 0;
#ifdef LP_STATS
	struct lp_stats *stats;
#endif

	if (signal_pending(current))
		return 0;

	for (;;)
	{
		unsigned char status;
		int irq_ok = 0;

		/*
		 * Give a chance to other pardevice to run in the meantime.
		 */
		lp_yield(minor);

		status = r_str(minor);
		if (LP_NO_ERROR(status))
		{
			if (LP_READY(status))
				break;

			/*
			 * This is a crude hack that should be well known
			 * at least by Epson device driver developers. -arca
			 */
			irq_ok = (!LP_POLLED(minor) &&
				  LP_NO_ACKING(status) &&
				  lp_table[minor].irq_detected);
			if ((LP_F(minor) & LP_TRUST_IRQ) && irq_ok)
				break;
		}
		/*
		 * NOTE: if you run with irqs you _must_ use
		 * `tunelp /dev/lp? -c 1' to be rasonable efficient!
		 */
		if (++count == LP_CHAR(minor))
		{
			if (irq_ok)
			{
				static int first_time = 1;
				/*
				 * The printer is using a buggy handshake, so
				 * revert to polling to not overload the
				 * machine and warn the user that its printer
				 * could get optimized trusting the irq. -arca
				 */
				lp_table[minor].irq_missed = 1;
				if (first_time)
				{
					first_time = 0;
					printk(KERN_WARNING "lp%d: the "
					       "printing could be optimized "
					       "using the TRUST_IRQ flag, "
					       "see the top of "
					       "linux/drivers/char/lp.c\n",
					       minor);
				}
			}
			return 0;
		}
	}

	w_dtr(minor, lpchar);

#ifdef LP_STATS
	stats = &LP_STAT(minor);
	stats->chars++;
#endif

	/* must wait before taking strobe high, and after taking strobe
	   low, according spec.  Some printers need it, others don't. */
	lp_wait(minor);

	/* control port takes strobe high */
	if (LP_POLLED(minor))
	{
		w_ctr(minor, LP_PSELECP | LP_PINITP | LP_PSTROBE);
		lp_wait(minor);
		w_ctr(minor, LP_PSELECP | LP_PINITP);
	} else {
		/*
		 * Epson Stylus Color generate the IRQ on the rising edge of
		 * strobe so clean the irq's information before playing with
		 * the strobe. -arca
		 */
		lp_table[minor].irq_detected = 0;
		lp_table[minor].irq_missed = 0;
		/*
		 * Be sure that the CPU doesn' t reorder instructions. -arca
		 */
		mb();
		w_ctr(minor, LP_PSELECP | LP_PINITP | LP_PSTROBE | LP_PINTEN);
		lp_wait(minor);
		w_ctr(minor, LP_PSELECP | LP_PINITP | LP_PINTEN);
	}

	/*
	 * Give to the printer a chance to put BUSY low. Really we could
	 * remove this because we could _guess_ that we are slower to reach
	 * again lp_char() than the printer to put BUSY low, but I' d like
	 * to remove this variable from the function I go solve
	 * when I read bug reports ;-). -arca
	 */
	lp_wait(minor);

#ifdef LP_STATS
	/* update waittime statistics */
	if (count > stats->maxwait) {
#ifdef LP_DEBUG
		printk(KERN_DEBUG "lp%d success after %d counts.\n",
		       minor, count);
#endif
		stats->maxwait = count;
	}
	count *= 256;
	wait = (count > stats->meanwait) ? count - stats->meanwait :
	    stats->meanwait - count;
	stats->meanwait = (255 * stats->meanwait + count + 128) / 256;
	stats->mdev = ((127 * stats->mdev) + wait + 64) / 128;
#endif

	return 1;
}

static void lp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct lp_struct *lp_dev = (struct lp_struct *) dev_id;

	if (waitqueue_active (&lp_dev->wait_q))
		wake_up_interruptible(&lp_dev->wait_q);

	lp_dev->irq_detected = 1;
	lp_dev->irq_missed = 0;
}

static void lp_error(int minor)
{
	if (LP_POLLED(minor) || LP_PREEMPTED(minor)) {
		current->state = TASK_INTERRUPTIBLE;
		lp_parport_release(minor);
		current->state = TASK_INTERRUPTIBLE;
		schedule_timeout(LP_TIMEOUT_POLLED);
		lp_parport_claim(minor);
		lp_table[minor].irq_missed = 1;
	}
}

static int lp_check_status(int minor)
{
	unsigned int last = lp_table[minor].last_error;
	unsigned char status = r_str(minor);
	if ((status & LP_PERRORP) && !(LP_F(minor) & LP_CAREFUL))
		/* No error. */
		last = 0;
	else if ((status & LP_POUTPA)) {
		if (last != LP_POUTPA) {
			last = LP_POUTPA;
			printk(KERN_INFO "lp%d out of paper\n", minor);
		}
	} else if (!(status & LP_PSELECD)) {
		if (last != LP_PSELECD) {
			last = LP_PSELECD;
			printk(KERN_INFO "lp%d off-line\n", minor);
		}
	} else if (!(status & LP_PERRORP)) {
		if (last != LP_PERRORP) {
			last = LP_PERRORP;
			printk(KERN_INFO "lp%d on fire\n", minor);
		}
	} else {
		last = 0; /* Come here if LP_CAREFUL is set and no
                             errors are reported. */
	}

	lp_table[minor].last_error = last;

	if (last != 0) {
		if (LP_F(minor) & LP_ABORT)
			return 1;
		lp_error(minor);
	}

	return 0;
}

static int lp_write_buf(unsigned int minor, const char *buf, int count)
{
	unsigned long copy_size;
	unsigned long total_bytes_written = 0;
	unsigned long bytes_written;
	struct lp_struct *lp = &lp_table[minor];

	if (minor >= LP_NO)
		return -ENXIO;
	if (lp->dev == NULL)
		return -ENXIO;

	lp_table[minor].last_error = 0;
	lp_table[minor].irq_detected = 0;
	lp_table[minor].irq_missed = 1;

	if (LP_POLLED(minor))
		w_ctr(minor, LP_PSELECP | LP_PINITP);
	else
		w_ctr(minor, LP_PSELECP | LP_PINITP | LP_PINTEN);

	do {
		bytes_written = 0;
		copy_size = (count <= LP_BUFFER_SIZE ? count : LP_BUFFER_SIZE);

		if (copy_from_user(lp->lp_buffer, buf, copy_size))
		{
			w_ctr(minor, LP_PSELECP | LP_PINITP);
			return -EFAULT;
		}

		while (copy_size) {
			if (lp_char(lp->lp_buffer[bytes_written], minor)) {
				--copy_size;
				++bytes_written;
#ifdef LP_STATS
				lp->runchars++;
#endif
			} else {
				int rc = total_bytes_written + bytes_written;

#ifdef LP_STATS
				if (lp->runchars > LP_STAT(minor).maxrun)
					LP_STAT(minor).maxrun = lp->runchars;
				LP_STAT(minor).sleeps++;
#endif

				if (signal_pending(current))
				{
					w_ctr(minor, LP_PSELECP | LP_PINITP);
					if (total_bytes_written + bytes_written)
						return total_bytes_written + bytes_written;