/*
   * IEEE 1284.3 Parallel port daisy chain and multiplexor code
   * 
   * Copyright (C) 1999, 2000  Tim Waugh <tim@cyberelk.demon.co.uk>
   *
   * 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/module.h>
  #include <linux/parport.h>
  #include <linux/delay.h>

  #include <linux/slab.h>

  #include <linux/sched.h>
  
  #include <asm/current.h>
  #include <asm/uaccess.h>
  
  #undef DEBUG
  
  #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 DEFINE_SPINLOCK(topology_lock);
  
  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, **p;

  	newdev = kmalloc(sizeof(struct daisydev), GFP_KERNEL);

  	if (newdev) {
  		newdev->port = port;
  		newdev->daisy = daisy;
  		newdev->devnum = devnum;
  		spin_lock(&topology_lock);
  		for (p = &topology; *p && (*p)->devnum<devnum; p = &(*p)->next)
  			;
  		newdev->next = *p;
  		*p = newdev;
  		spin_unlock(&topology_lock);
  	}
  }
  
  /* 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;
  		real->slaves[muxport-1] = extra;
  	}
  
  	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;
  	int last_try = 0;
  
  again:
  	/* 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
  ",
  			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
  ",
  				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_daisy_init(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(1024, GFP_KERNEL);

  	if (deviceid) {

  		if (parport_device_id(numdevs - 1, deviceid, 1024) > 2)

  			detected++;

  		kfree(deviceid);

  	}
  
  	if (!detected && !last_try) {
  		/* No devices were detected.  Perhaps they are in some
                     funny state; let's try to reset them and see if
                     they wake up. */

  		parport_daisy_fini(port);
  		parport_write_control(port, PARPORT_CONTROL_SELECT);
  		udelay(50);
  		parport_write_control(port,

  				       PARPORT_CONTROL_SELECT |
  				       PARPORT_CONTROL_INIT);

  		udelay(50);

  		last_try = 1;
  		goto again;
  	}
  
  	return detected;
  }
  
  /* Forget about devices on a physical port. */

  void parport_daisy_fini(struct parport *port)

  {
  	struct daisydev **p;
  
  	spin_lock(&topology_lock);
  	p = &topology;
  	while (*p) {
  		struct daisydev *dev = *p;
  		if (dev->port != port) {
  			p = &dev->next;
  			continue;
  		}
  		*p = dev->next;
  		kfree(dev);
  	}
  
  	/* Gaps in the numbering could be handled better.  How should
             someone enumerate through all IEEE1284.3 devices in the
             topology?. */
  	if (!topology) numdevs = 0;
  	spin_unlock(&topology_lock);
  	return;
  }
  
  /**
   *	parport_open - find a device by canonical device number
   *	@devnum: canonical device number
   *	@name: name to associate with the device

   *
   *	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.
   *
   *	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)

  {
  	struct daisydev *p = topology;
  	struct parport *port;
  	struct pardevice *dev;
  	int daisy;
  
  	spin_lock(&topology_lock);
  	while (p && p->devnum != devnum)
  		p = p->next;
  
  	if (!p) {
  		spin_unlock(&topology_lock);
  		return NULL;
  	}
  
  	daisy = p->daisy;
  	port = parport_get_port(p->port);
  	spin_unlock(&topology_lock);

  	dev = parport_register_device(port, name, NULL, NULL, NULL, 0, NULL);

  	parport_put_port(port);
  	if (!dev)
  		return NULL;
  
  	dev->daisy = daisy;
  
  	/* Check that there really is a device to select. */
  	if (daisy >= 0) {
  		int selected;

  		parport_claim_or_block(dev);

  		selected = port->daisy;

  		parport_release(dev);

  		if (selected != 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);

  }

  /* Send a daisy-chain-style CPP command packet. */

  static int cpp_daisy(struct parport *port, int cmd)

  {
  	unsigned char s;

  	parport_data_forward(port);
  	parport_write_data(port, 0xaa); udelay(2);
  	parport_write_data(port, 0x55); udelay(2);
  	parport_write_data(port, 0x00); udelay(2);
  	parport_write_data(port, 0xff); udelay(2);
  	s = parport_read_status(port) & (PARPORT_STATUS_BUSY

  					  | PARPORT_STATUS_PAPEROUT
  					  | PARPORT_STATUS_SELECT
  					  | PARPORT_STATUS_ERROR);
  	if (s != (PARPORT_STATUS_BUSY
  		  | PARPORT_STATUS_PAPEROUT
  		  | PARPORT_STATUS_SELECT
  		  | PARPORT_STATUS_ERROR)) {

  		DPRINTK(KERN_DEBUG "%s: cpp_daisy: aa5500ff(%02x)
  ",

  			 port->name, s);
  		return -ENXIO;
  	}

  	parport_write_data(port, 0x87); udelay(2);
  	s = parport_read_status(port) & (PARPORT_STATUS_BUSY

  					  | PARPORT_STATUS_PAPEROUT
  					  | PARPORT_STATUS_SELECT
  					  | PARPORT_STATUS_ERROR);
  	if (s != (PARPORT_STATUS_SELECT | PARPORT_STATUS_ERROR)) {

  		DPRINTK(KERN_DEBUG "%s: cpp_daisy: aa5500ff87(%02x)
  ",

  			 port->name, s);
  		return -ENXIO;
  	}

  	parport_write_data(port, 0x78); udelay(2);
  	parport_write_data(port, cmd); udelay(2);
  	parport_frob_control(port,

  			      PARPORT_CONTROL_STROBE,
  			      PARPORT_CONTROL_STROBE);

  	udelay(1);
  	s = parport_read_status(port);
  	parport_frob_control(port, PARPORT_CONTROL_STROBE, 0);
  	udelay(1);
  	parport_write_data(port, 0xff); udelay(2);

  
  	return s;
  }
  
  /* Send a mux-style CPP command packet. */

  static int cpp_mux(struct parport *port, int cmd)

  {
  	unsigned char s;
  	int rc;

  	parport_data_forward(port);
  	parport_write_data(port, 0xaa); udelay(2);
  	parport_write_data(port, 0x55); udelay(2);
  	parport_write_data(port, 0xf0); udelay(2);
  	parport_write_data(port, 0x0f); udelay(2);
  	parport_write_data(port, 0x52); udelay(2);
  	parport_write_data(port, 0xad); udelay(2);
  	parport_write_data(port, cmd); udelay(2);

  	s = parport_read_status(port);

  	if (!(s & PARPORT_STATUS_ACK)) {

  		DPRINTK(KERN_DEBUG "%s: cpp_mux: aa55f00f52ad%02x(%02x)
  ",

  			 port->name, cmd, s);
  		return -EIO;
  	}
  
  	rc = (((s & PARPORT_STATUS_SELECT   ? 1 : 0) << 0) |
  	      ((s & PARPORT_STATUS_PAPEROUT ? 1 : 0) << 1) |
  	      ((s & PARPORT_STATUS_BUSY     ? 0 : 1) << 2) |
  	      ((s & PARPORT_STATUS_ERROR    ? 0 : 1) << 3));
  
  	return rc;
  }

  void parport_daisy_deselect_all(struct parport *port)

  {

  	cpp_daisy(port, 0x30);

  }

  int parport_daisy_select(struct parport *port, int daisy, int mode)

  {
  	switch (mode)
  	{
  		// For these modes we should switch to EPP mode:
  		case IEEE1284_MODE_EPP:
  		case IEEE1284_MODE_EPPSL:
  		case IEEE1284_MODE_EPPSWE:

  			return !(cpp_daisy(port, 0x20 + daisy) &

  				 PARPORT_STATUS_ERROR);

  
  		// For these modes we should switch to ECP mode:
  		case IEEE1284_MODE_ECP:
  		case IEEE1284_MODE_ECPRLE:
  		case IEEE1284_MODE_ECPSWE: 

  			return !(cpp_daisy(port, 0xd0 + daisy) &

  				 PARPORT_STATUS_ERROR);

  
  		// Nothing was told for BECP in Daisy chain specification.
  		// May be it's wise to use ECP?
  		case IEEE1284_MODE_BECP:
  		// Others use compat mode
  		case IEEE1284_MODE_NIBBLE:
  		case IEEE1284_MODE_BYTE:
  		case IEEE1284_MODE_COMPAT:
  		default:

  			return !(cpp_daisy(port, 0xe0 + daisy) &

  				 PARPORT_STATUS_ERROR);

  	}
  }

  static int mux_present(struct parport *port)

  {

  	return cpp_mux(port, 0x51) == 3;

  }

  static int num_mux_ports(struct parport *port)

  {

  	return cpp_mux(port, 0x58);

  }

  static int select_port(struct parport *port)

  {
  	int muxport = port->muxport;

  	return cpp_mux(port, 0x60 + muxport) == muxport;

  }

  static int assign_addrs(struct parport *port)

  {

  	unsigned char s;

  	unsigned char daisy;
  	int thisdev = numdevs;
  	int detected;
  	char *deviceid;

  	parport_data_forward(port);
  	parport_write_data(port, 0xaa); udelay(2);
  	parport_write_data(port, 0x55); udelay(2);
  	parport_write_data(port, 0x00); udelay(2);
  	parport_write_data(port, 0xff); udelay(2);
  	s = parport_read_status(port) & (PARPORT_STATUS_BUSY

  					  | PARPORT_STATUS_PAPEROUT
  					  | PARPORT_STATUS_SELECT
  					  | PARPORT_STATUS_ERROR);
  	if (s != (PARPORT_STATUS_BUSY
  		  | PARPORT_STATUS_PAPEROUT
  		  | PARPORT_STATUS_SELECT
  		  | PARPORT_STATUS_ERROR)) {

  		DPRINTK(KERN_DEBUG "%s: assign_addrs: aa5500ff(%02x)
  ",

  			 port->name, s);
  		return 0;
  	}

  	parport_write_data(port, 0x87); udelay(2);
  	s = parport_read_status(port) & (PARPORT_STATUS_BUSY

  					  | PARPORT_STATUS_PAPEROUT
  					  | PARPORT_STATUS_SELECT
  					  | PARPORT_STATUS_ERROR);
  	if (s != (PARPORT_STATUS_SELECT | PARPORT_STATUS_ERROR)) {

  		DPRINTK(KERN_DEBUG "%s: assign_addrs: aa5500ff87(%02x)
  ",

  			 port->name, s);
  		return 0;
  	}

  	parport_write_data(port, 0x78); udelay(2);
  	s = parport_read_status(port);

  	for (daisy = 0;
  	     (s & (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT))
  		     == (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT)
  		     && daisy < 4;
  	     ++daisy) {

  		parport_write_data(port, daisy);
  		udelay(2);
  		parport_frob_control(port,

  				      PARPORT_CONTROL_STROBE,
  				      PARPORT_CONTROL_STROBE);

  		udelay(1);
  		parport_frob_control(port, PARPORT_CONTROL_STROBE, 0);
  		udelay(1);

  		add_dev(numdevs++, port, daisy);

  		/* See if this device thought it was the last in the
  		 * chain. */
  		if (!(s & PARPORT_STATUS_BUSY))
  			break;

  		/* We are seeing pass through status now. We see
  		   last_dev from next device or if last_dev does not
  		   work status lines from some non-daisy chain
  		   device. */

  		s = parport_read_status(port);

  	}

  	parport_write_data(port, 0xff); udelay(2);

  	detected = numdevs - thisdev;

  	DPRINTK(KERN_DEBUG "%s: Found %d daisy-chained devices
  ", port->name,

  		 detected);
  
  	/* Ask the new devices to introduce themselves. */

  	deviceid = kmalloc(1024, GFP_KERNEL);

  	if (!deviceid) return 0;
  
  	for (daisy = 0; thisdev < numdevs; thisdev++, daisy++)

  		parport_device_id(thisdev, deviceid, 1024);

  	kfree(deviceid);

  	return detected;
  }