path: root/drivers/parport/share.c

/* $Id: parport_share.c,v 1.15 1998/01/11 12:06:17 philip Exp $
 * Parallel-port resource manager code.
 * 
 * Authors: David Campbell <campbell@tirian.che.curtin.edu.au>
 *          Tim Waugh <tim@cyberelk.demon.co.uk>
 *          Jose Renau <renau@acm.org>
 *          Philip Blundell <philb@gnu.org>
 *	    Andrea Arcangeli
 *
 * based on work by Grant Guenther <grant@torque.net>
 *          and Philip Blundell
 *
 * Any part of this program may be used in documents licensed under
 * the GNU Free Documentation License, Version 1.1 or any later version
 * published by the Free Software Foundation.
 */

#undef PARPORT_DEBUG_SHARING		/* undef for production */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/threads.h>
#include <linux/parport.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/kmod.h>

#include <linux/spinlock.h>
#include <asm/irq.h>

#undef PARPORT_PARANOID

#define PARPORT_DEFAULT_TIMESLICE	(HZ/5)

unsigned long parport_default_timeslice = PARPORT_DEFAULT_TIMESLICE;
int parport_default_spintime =  DEFAULT_SPIN_TIME;

static LIST_HEAD(portlist);
static DEFINE_SPINLOCK(parportlist_lock);

/* list of all allocated ports, sorted by ->number */
static LIST_HEAD(all_ports);
static DEFINE_SPINLOCK(full_list_lock);

static LIST_HEAD(drivers);

static DECLARE_MUTEX(registration_lock);

/* What you can do to a port that's gone away.. */
static void dead_write_lines (struct parport *p, unsigned char b){}
static unsigned char dead_read_lines (struct parport *p) { return 0; }
static unsigned char dead_frob_lines (struct parport *p, unsigned char b,
			     unsigned char c) { return 0; }
static void dead_onearg (struct parport *p){}
static void dead_initstate (struct pardevice *d, struct parport_state *s) { }
static void dead_state (struct parport *p, struct parport_state *s) { }
static size_t dead_write (struct parport *p, const void *b, size_t l, int f)
{ return 0; }
static size_t dead_read (struct parport *p, void *b, size_t l, int f)
{ return 0; }
static struct parport_operations dead_ops = {
	.write_data	= dead_write_lines,	/* data */
	.read_data	= dead_read_lines,

	.write_control	= dead_write_lines,	/* control */
	.read_control	= dead_read_lines,
	.frob_control	= dead_frob_lines,

	.read_status	= dead_read_lines,	/* status */

	.enable_irq	= dead_onearg,		/* enable_irq */
	.disable_irq	= dead_onearg,		/* disable_irq */

	.data_forward	= dead_onearg,		/* data_forward */
	.data_reverse	= dead_onearg,		/* data_reverse */

	.init_state	= dead_initstate,	/* init_state */
	.save_state	= dead_state,
	.restore_state	= dead_state,

	.epp_write_data	= dead_write,		/* epp */
	.epp_read_data	= dead_read,
	.epp_write_addr	= dead_write,
	.epp_read_addr	= dead_read,

	.ecp_write_data	= dead_write,		/* ecp */
	.ecp_read_data	= dead_read,
	.ecp_write_addr	= dead_write,
 
	.compat_write_data	= dead_write,	/* compat */
	.nibble_read_data	= dead_read,	/* nibble */
	.byte_read_data		= dead_read,	/* byte */

	.owner		= NULL,
};

/* Call attach(port) for each registered driver. */
static void attach_driver_chain(struct parport *port)
{
	/* caller has exclusive registration_lock */
	struct parport_driver *drv;
	list_for_each_entry(drv, &drivers, list)
		drv->attach(port);
}

/* Call detach(port) for each registered driver. */
static void detach_driver_chain(struct parport *port)
{
	struct parport_driver *drv;
	/* caller has exclusive registration_lock */
	list_for_each_entry(drv, &drivers, list)
		drv->detach (port);
}

/* Ask kmod for some lowlevel drivers. */
static void get_lowlevel_driver (void)
{
	/* There is no actual module called this: you should set
	 * up an alias for modutils. */
	request_module ("parport_lowlevel");
}

/**
 *	parport_register_driver - register a parallel port device driver
 *	@drv: structure describing the driver
 *
 *	This can be called by a parallel port device driver in order
 *	to receive notifications about ports being found in the
 *	system, as well as ports no longer available.
 *
 *	The @drv structure is allocated by the caller and must not be
 *	deallocated until after calling parport_unregister_driver().
 *
 *	The driver's attach() function may block.  The port that
 *	attach() is given will be valid for the duration of the
 *	callback, but if the driver wants to take a copy of the
 *	pointer it must call parport_get_port() to do so.  Calling
 *	parport_register_device() on that port will do this for you.
 *
 *	The driver's detach() function may block.  The port that
 *	detach() is given will be valid for the duration of the
 *	callback, but if the driver wants to take a copy of the
 *	pointer it must call parport_get_port() to do so.
 *
 *	Returns 0 on success.  Currently it always succeeds.
 **/

int parport_register_driver (struct parport_driver *drv)
{
	struct parport *port;

	if (list_empty(&portlist))
		get_lowlevel_driver ();

	down