text: /*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (c) 2004-2005 Silicon Graphics, Inc.  All Rights Reserved.
   */
  
  
  /*
   * Cross Partition (XP) base.
   *
   *	XP provides a base from which its users can interact
   *	with XPC, yet not be dependent on XPC.
   *
   */
  
  
  #include <linux/kernel.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <asm/sn/intr.h>
  #include <asm/sn/sn_sal.h>
  #include <asm/sn/xp.h>
  
  
  /*
   * Target of nofault PIO read.
   */
  u64 xp_nofault_PIOR_target;
  
  
  /*
   * xpc_registrations[] keeps track of xpc_connect()'s done by the kernel-level
   * users of XPC.
   */
  struct xpc_registration xpc_registrations[XPC_NCHANNELS];
  
  
  /*
   * Initialize the XPC interface to indicate that XPC isn't loaded.
   */
  static enum xpc_retval xpc_notloaded(void) { return xpcNotLoaded; }
  
  struct xpc_interface xpc_interface = {
  	(void (*)(int)) xpc_notloaded,
  	(void (*)(int)) xpc_notloaded,
  	(enum xpc_retval (*)(partid_t, int, u32, void **)) xpc_notloaded,
  	(enum xpc_retval (*)(partid_t, int, void *)) xpc_notloaded,
  	(enum xpc_retval (*)(partid_t, int, void *, xpc_notify_func, void *))
  							xpc_notloaded,
  	(void (*)(partid_t, int, void *)) xpc_notloaded,
  	(enum xpc_retval (*)(partid_t, void *)) xpc_notloaded
  };
  
  
  /*
   * XPC calls this when it (the XPC module) has been loaded.
   */
  void
  xpc_set_interface(void (*connect)(int),
  		void (*disconnect)(int),
  		enum xpc_retval (*allocate)(partid_t, int, u32, void **),
  		enum xpc_retval (*send)(partid_t, int, void *),
  		enum xpc_retval (*send_notify)(partid_t, int, void *,
  						xpc_notify_func, void *),
  		void (*received)(partid_t, int, void *),
  		enum xpc_retval (*partid_to_nasids)(partid_t, void *))
  {
  	xpc_interface.connect = connect;
  	xpc_interface.disconnect = disconnect;
  	xpc_interface.allocate = allocate;
  	xpc_interface.send = send;
  	xpc_interface.send_notify = send_notify;
  	xpc_interface.received = received;
  	xpc_interface.partid_to_nasids = partid_to_nasids;
  }
  
  
  /*
   * XPC calls this when it (the XPC module) is being unloaded.
   */
  void
  xpc_clear_interface(void)
  {
  	xpc_interface.connect = (void (*)(int)) xpc_notloaded;
  	xpc_interface.disconnect = (void (*)(int)) xpc_notloaded;
  	xpc_interface.allocate = (enum xpc_retval (*)(partid_t, int, u32,
  					void **)) xpc_notloaded;
  	xpc_interface.send = (enum xpc_retval (*)(partid_t, int, void *))
  					xpc_notloaded;
  	xpc_interface.send_notify = (enum xpc_retval (*)(partid_t, int, void *,
  				    xpc_notify_func, void *)) xpc_notloaded;
  	xpc_interface.received = (void (*)(partid_t, int, void *))
  					xpc_notloaded;
  	xpc_interface.partid_to_nasids = (enum xpc_retval (*)(partid_t, void *))
  					xpc_notloaded;
  }
  
  
  /*
   * Register for automatic establishment of a channel connection whenever
   * a partition comes up.
   *
   * Arguments:
   *
   *	ch_number - channel # to register for connection.
   *	func - function to call for asynchronous notification of channel
   *	       state changes (i.e., connection, disconnection, error) and
   *	       the arrival of incoming messages.
   *      key - pointer to optional user-defined value that gets passed back
   *	      to the user on any callouts made to func.
   *	payload_size - size in bytes of the XPC message's payload area which
   *		       contains a user-defined message. The user should make
   *		       this large enough to hold their largest message.
   *	nentries - max #of XPC message entries a message queue can contain.
   *		   The actual number, which is determined when a connection
   * 		   is established and may be less then requested, will be
   *		   passed to the user via the xpcConnected callout.
   *	assigned_limit - max number of kthreads allowed to be processing
   * 			 messages (per connection) at any given instant.
   *	idle_limit - max number of kthreads allowed to be idle at any given
   * 		     instant.
   */
  enum xpc_retval
  xpc_connect(int ch_number, xpc_channel_func func, void *key, u16 payload_size,
  		u16 nentries, u32 assigned_limit, u32 idle_limit)
  {
  	struct xpc_registration *registration;
  
  
  	DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
  	DBUG_ON(payload_size == 0 || nentries == 0);
  	DBUG_ON(func == NULL);
  	DBUG_ON(assigned_limit == 0 || idle_limit > assigned_limit);
  
  	registration = &xpc_registrations[ch_number];
  
  	if (mutex_lock_interruptible(&registration->mutex) != 0) {
  		return xpcInterrupted;
  	}
  
  	/* if XPC_CHANNEL_REGISTERED(ch_number) */
  	if (registration->func != NULL) {
  		mutex_unlock(&registration->mutex);
  		return xpcAlreadyRegistered;
  	}
  
  	/* register the channel for connection */
  	registration->msg_size = XPC_MSG_SIZE(payload_size);
  	registration->nentries = nentries;
  	registration->assigned_limit = assigned_limit;
  	registration->idle_limit = idle_limit;
  	registration->key = key;
  	registration->func = func;
  
  	mutex_unlock(&registration->mutex);
  
  	xpc_interface.connect(ch_number);
  
  	return xpcSuccess;
  }
  
  
  /*
   * Remove the registration for automatic connection of the specified channel
   * when a partition comes up.
   *
   * Before returning this xpc_disconnect() will wait for all connections on the
   * specified channel have been closed/torndown. So the caller can be assured
   * that they will not be receiving any more callouts from XPC to their
   * function registered via xpc_connect().
   *
   * Arguments:
   *
   *	ch_number - channel # to unregister.
   */
  void
  xpc_disconnect(int ch_number)
  {
  	struct xpc_registration *registration;
  
  
  	DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
  
  	registration = &xpc_registrations[ch_number];
  
  	/*
  	 * We've decided not to make this a down_interruptible(), since we
  	 * figured XPC's users will just turn around and call xpc_disconnect()
  	 * again anyways, so we might as well wait, if need be.
  	 */
  	mutex_lock(&registration->mutex);
  
  	/* if !XPC_CHANNEL_REGISTERED(ch_number) */
  	if (registration->func == NULL) {
  		mutex_unlock(&registration->mutex);
  		return;
  	}
  
  	/* remove the connection registration for the specified channel */
  	registration->func = NULL;
  	registration->key = NULL;
  	registration->nentries = 0;
  	registration->msg_size = 0;
  	registration->assigned_limit = 0;
  	registration->idle_limit = 0;
  
  	xpc_interface.disconnect(ch_number);
  
  	mutex_unlock(&registration->mutex);
  
  	return;
  }
  
  
  int __init
  xp_init(void)
  {
  	int ret, ch_number;
  	u64 func_addr = *(u64 *) xp_nofault_PIOR;
  	u64 err_func_addr = *(u64 *) xp_error_PIOR;
  
  
  	if (!ia64_platform_is("sn2")) {
  		return -ENODEV;
  	}
  
  	/*
  	 * Register a nofault code region which performs a cross-partition
  	 * PIO read. If the PIO read times out, the MCA handler will consume
  	 * the error and return to a kernel-provided instruction to indicate
  	 * an error. This PIO read exists because it is guaranteed to timeout
  	 * if the destination is down (AMO operations do not timeout on at
  	 * least some CPUs on Shubs <= v1.2, which unfortunately we have to
  	 * work around).
  	 */
  	if ((ret = sn_register_nofault_code(func_addr, err_func_addr,
  						err_func_addr, 1, 1)) != 0) {
  		printk(KERN_ERR "XP: can't register nofault code, error=%d\n",
  			ret);
  	}
  	/*
  	 * Setup the nofault PIO read target. (There is no special reason why
  	 * SH_IPI_ACCESS was selected.)
  	 */
  	if (is_shub2()) {
  		xp_nofault_PIOR_target = SH2_IPI_ACCESS0;
  	} else {
  		xp_nofault_PIOR_target = SH1_IPI_ACCESS;
  	}
  
  	/* initialize the connection registration mutex */
  	for (ch_number = 0; ch_number < XPC_NCHANNELS; ch_number++) {
  		mutex_init(&xpc_registrations[ch_number].mutex);
  	}
  
  	return 0;
  }
  module_init(xp_init);
  
  
  void __exit
  xp_exit(void)
  {
  	u64 func_addr = *(u64 *) xp_nofault_PIOR;
  	u64 err_func_addr = *(u64 *) xp_error_PIOR;
  
  
  	/* unregister the PIO read nofault code region */
  	(void) sn_register_nofault_code(func_addr, err_func_addr,
  					err_func_addr, 1, 0);
  }
  module_exit(xp_exit);
  
  
  MODULE_AUTHOR("Silicon Graphics, Inc.");
  MODULE_DESCRIPTION("Cross Partition (XP) base");
  MODULE_LICENSE("GPL");
  
  EXPORT_SYMBOL(xp_nofault_PIOR);
  EXPORT_SYMBOL(xp_nofault_PIOR_target);
  EXPORT_SYMBOL(xpc_registrations);
  EXPORT_SYMBOL(xpc_interface);
  EXPORT_SYMBOL(xpc_clear_interface);
  EXPORT_SYMBOL(xpc_set_interface);
  EXPORT_SYMBOL(xpc_connect);
  EXPORT_SYMBOL(xpc_disconnect);
  
  