daisy.c

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/*
 * IEEE 1284.3 Parallel port daisy chain and multiplexor code
 * 
 * Copyright (C) 1999, 2000  Tim Waugh <[e-mail]>
 *
 * 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.
 *
 * ??-12-1998: Initial implementation.
 * 31-01-1999: Make port-cloning transparent.
 * 13-02-1999: Move DeviceID technique from parport_probe.
 * 13-03-1999: Get DeviceID from non-IEEE 1284.3 devices too.
 * 22-02-2000: Count devices that are actually detected.
 *
 * 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.
 */

#include <linux/parport.h>
#include <linux/delay.h>
#include <asm/uaccess.h>

#define DEBUG /* undef me for production */

#ifdef DEBUG
#define DPRINTK(stuff...) printk (stuff)
#else
#define DPRINTK(stuff...)
#endif

static struct daisydev {
	struct daisydev *next;
	struct parport *port;
	int daisy;
	int devnum;
} *topology = NULL;

static int numdevs = 0;

/* Forward-declaration of lower-level functions. */
static int mux_present (struct parport *port);
static int num_mux_ports (struct parport *port);
static int select_port (struct parport *port);
static int assign_addrs (struct parport *port);

/* Add a device to the discovered topology. */
static void add_dev (int devnum, struct parport *port, int daisy)
{
	struct daisydev *newdev;
	newdev = kmalloc (sizeof (struct daisydev), GFP_KERNEL);
	if (newdev) {
		newdev->port = port;
		newdev->daisy = daisy;
		newdev->devnum = devnum;
		newdev->next = topology;
		if (!topology || topology->devnum >= devnum)
			topology = newdev;
		else {
			struct daisydev *prev = topology;
			while (prev->next && prev->next->devnum < devnum)
				prev = prev->next;
			newdev->next = prev->next;
			prev->next = newdev;
		}
	}
}

/* Clone a parport (actually, make an alias). */
static struct parport *clone_parport (struct parport *real, int muxport)
{
	struct parport *extra = parport_register_port (real->base,
						       real->irq,
						       real->dma,
						       real->ops);
	if (extra) {
		extra->portnum = real->portnum;
		extra->physport = real;
		extra->muxport = muxport;
	}

	return extra;
}

/* Discover the IEEE1284.3 topology on a port -- muxes and daisy chains.
 * Return value is number of devices actually detected. */
int parport_daisy_init (struct parport *port)
{
	int detected = 0;
	char *deviceid;
	static const char *th[] = { /*0*/"th", "st", "nd", "rd", "th" };
	int num_ports;
	int i;

	/* Because this is called before any other devices exist,
	 * we don't have to claim exclusive access.  */

	/* If mux present on normal port, need to create new
	 * parports for each extra port. */
	if (port->muxport < 0 && mux_present (port) &&
	    /* don't be fooled: a mux must have 2 or 4 ports. */
	    ((num_ports = num_mux_ports (port)) == 2 || num_ports == 4)) {
		/* Leave original as port zero. */
		port->muxport = 0;
		printk (KERN_INFO
			"%s: 1st (default) port of %d-way multiplexor\n",
			port->name, num_ports);
		for (i = 1; i < num_ports; i++) {
			/* Clone the port. */
			struct parport *extra = clone_parport (port, i);
			if (!extra) {
				if (signal_pending (current))
					break;

				schedule ();
				continue;
			}

			printk (KERN_INFO
				"%s: %d%s port of %d-way multiplexor on %s\n",
				extra->name, i + 1, th[i + 1], num_ports,
				port->name);

			/* Analyse that port too.  We won't recurse
			   forever because of the 'port->muxport < 0'
			   test above. */
			parport_announce_port (extra);
		}
	}

	if (port->muxport >= 0)
		select_port (port);

	parport_daisy_deselect_all (port);
	detected += assign_addrs (port);

	/* Count the potential legacy device at the end. */
	add_dev (numdevs++, port, -1);

	/* Find out the legacy device's IEEE 1284 device ID. */
	deviceid = kmalloc (1000, GFP_KERNEL);
	if (deviceid) {
		if (parport_device_id (numdevs - 1, deviceid, 1000) > 2)
			detected++;

		kfree (deviceid);
	}

	return detected;
}

/* Forget about devices on a physical port. */
void parport_daisy_fini (struct parport *port)
{
	struct daisydev *dev, *prev = topology;
	while (prev && prev->port == port) {
		topology = topology->next;
		kfree (prev);
		prev = topology;
	}

	while (prev) {
		dev = prev->next;
		if (dev && dev->port == port) {
			prev->next = dev->next;
			kfree (dev);
		}
		prev = prev->next;
	}

	/* Gaps in the numbering could be handled better.  How should
           someone enumerate through all IEEE1284.3 devices in the
           topology?. */
	if (!topology) numdevs = 0;
	return;
}

/**
 *	parport_open - find a device by canonical device number
 *	@devnum: canonical device number
 *	@name: name to associate with the device
 *	@pf: preemption callback
 *	@kf: kick callback
 *	@irqf: interrupt handler
 *	@flags: registration flags
 *	@handle: driver data
 *
 *	This function is similar to parport_register_device(), except
 *	that it locates a device by its number rather than by the port
 *	it is attached to.  See parport_find_device() and
 *	parport_find_class().
 *
 *	All parameters except for @devnum are the same as for
 *	parport_register_device().  The return value is the same as
 *	for parport_register_device().
 **/

struct pardevice *parport_open (int devnum, const char *name,
				int (*pf) (void *), void (*kf) (void *),
				void (*irqf) (int, void *, struct pt_regs *),
				int flags, void *handle)
{
	struct parport *port = parport_enumerate ();
	struct pardevice *dev;
	int portnum;
	int muxnum;
	int daisynum;

	if (parport_device_coords (devnum,  &portnum, &muxnum, &daisynum))
		return NULL;

	while (port && ((port->portnum != portnum) ||
			(port->muxport != muxnum)))
		port = port->next;

	if (!port)
		/* No corresponding parport. */
		return NULL;

	dev = parport_register_device (port, name, pf, kf,
				       irqf, flags, handle);
	if (dev)
		dev->daisy = daisynum;

	/* Check that there really is a device to select. */
	if (daisynum >= 0) {
		int selected;
		parport_claim_or_block (dev);
		selected = port->daisy;
		parport_release (dev);

		if (selected != port->daisy) {
			/* No corresponding device. */
			parport_unregister_device (dev);
			return NULL;
		}
	}

	return dev;
}

/**
 *	parport_close - close a device opened with parport_open()
 *	@dev: device to close
 *
 *	This is to parport_open() as parport_unregister_device() is to
 *	parport_register_device().
 **/

void parport_close (struct pardevice *dev)
{
	parport_unregister_device (dev);
}

/**
 *	parport_device_num - convert device coordinates
 *	@parport: parallel port number
 *	@mux: multiplexor port number (-1 for no multiplexor)
 *	@daisy: daisy chain address (-1 for no daisy chain address)
 *
 *	This tries to locate a device on the given parallel port,
 *	multiplexor port and daisy chain address, and returns its
 *	device number or -NXIO if no device with those coordinates
 *	exists.
 **/

int parport_device_num (int parport, int mux, int daisy)
{
	struct daisydev *dev = topology;

	while (dev && dev->port->portnum != parport &&
	       dev->port->muxport != mux && dev->daisy != daisy)
		dev = dev->next;

	if (!dev)
		return -ENXIO;

	return dev->devnum;
}

/**
 *	parport_device_coords - convert canonical device number
 *	@devnum: device number
 *	@parport: pointer to storage for parallel port number
 *	@mux: pointer to storage for multiplexor port number
 *	@daisy: pointer to storage for daisy chain address
 *
 *	This function converts a device number into its coordinates in
 *	terms of which parallel port in the system it is attached to,
 *	which multiplexor port it is attached to if there is a
 *	multiplexor on that port, and which daisy chain address it has
 *	if it is in a daisy chain.
 *
 *	The caller must allocate storage for @parport, @mux, and