/*
   * Copyright (C) 1992-1997, 2000-2003 Silicon Graphics, Inc.
   * Copyright (C) 2004 Christoph Hellwig.
   *	Released under GPL v2.
   *
   * Support functions for the HUB ASIC - mostly PIO mapping related.
   */
  
  #include <linux/bitops.h>
  #include <linux/string.h>
  #include <linux/mmzone.h>
  #include <asm/sn/addrs.h>
  #include <asm/sn/arch.h>
  #include <asm/sn/hub.h>
  
  
  static int force_fire_and_forget = 1;
  
  /**
   * hub_pio_map  -  establish a HUB PIO mapping
   *
   * @hub:	hub to perform PIO mapping on
   * @widget:	widget ID to perform PIO mapping for
   * @xtalk_addr:	xtalk_address that needs to be mapped
   * @size:	size of the PIO mapping
   *
   **/
  unsigned long hub_pio_map(cnodeid_t cnode, xwidgetnum_t widget,
  			  unsigned long xtalk_addr, size_t size)
  {
  	nasid_t nasid = COMPACT_TO_NASID_NODEID(cnode);

  	unsigned i;
  
  	/* use small-window mapping if possible */
  	if ((xtalk_addr % SWIN_SIZE) + size <= SWIN_SIZE)
  		return NODE_SWIN_BASE(nasid, widget) + (xtalk_addr % SWIN_SIZE);
  
  	if ((xtalk_addr % BWIN_SIZE) + size > BWIN_SIZE) {
  		printk(KERN_WARNING "PIO mapping at hub %d widget %d addr 0x%lx"
  				" too big (%ld)
  ",
  				nasid, widget, xtalk_addr, size);
  		return 0;
  	}
  
  	xtalk_addr &= ~(BWIN_SIZE-1);
  	for (i = 0; i < HUB_NUM_BIG_WINDOW; i++) {
  		if (test_and_set_bit(i, hub_data(cnode)->h_bigwin_used))
  			continue;
  
  		/*
  		 * The code below does a PIO write to setup an ITTE entry.
  		 *
  		 * We need to prevent other CPUs from seeing our updated
  		 * memory shadow of the ITTE (in the piomap) until the ITTE
  		 * entry is actually set up; otherwise, another CPU might
  		 * attempt a PIO prematurely.
  		 *
  		 * Also, the only way we can know that an entry has been
  		 * received  by the hub and can be used by future PIO reads/
  		 * writes is by reading back the ITTE entry after writing it.
  		 *
  		 * For these two reasons, we PIO read back the ITTE entry
  		 * after we write it.
  		 */
  		IIO_ITTE_PUT(nasid, i, HUB_PIO_MAP_TO_MEM, widget, xtalk_addr);

  		(void) HUB_L(IIO_ITTE_GET(nasid, i));

  
  		return NODE_BWIN_BASE(nasid, widget) + (xtalk_addr % BWIN_SIZE);
  	}
  
  	printk(KERN_WARNING "unable to establish PIO mapping for at"
  			" hub %d widget %d addr 0x%lx
  ",
  			nasid, widget, xtalk_addr);
  	return 0;
  }
  
  
  /*
   * hub_setup_prb(nasid, prbnum, credits, conveyor)
   *
   * 	Put a PRB into fire-and-forget mode if conveyor isn't set.  Otherwise,
   * 	put it into conveyor belt mode with the specified number of credits.
   */
  static void hub_setup_prb(nasid_t nasid, int prbnum, int credits)
  {
  	iprb_t prb;
  	int prb_offset;
  
  	/*
  	 * Get the current register value.
  	 */
  	prb_offset = IIO_IOPRB(prbnum);
  	prb.iprb_regval = REMOTE_HUB_L(nasid, prb_offset);
  
  	/*
  	 * Clear out some fields.
  	 */
  	prb.iprb_ovflow = 1;
  	prb.iprb_bnakctr = 0;
  	prb.iprb_anakctr = 0;
  
  	/*
  	 * Enable or disable fire-and-forget mode.
  	 */
  	prb.iprb_ff = force_fire_and_forget ? 1 : 0;
  
  	/*
  	 * Set the appropriate number of PIO cresits for the widget.
  	 */
  	prb.iprb_xtalkctr = credits;
  
  	/*
  	 * Store the new value to the register.
  	 */
  	REMOTE_HUB_S(nasid, prb_offset, prb.iprb_regval);
  }
  
  /**
   * hub_set_piomode  -  set pio mode for a given hub
   *
   * @nasid:	physical node ID for the hub in question
   *
   * Put the hub into either "PIO conveyor belt" mode or "fire-and-forget" mode.
   * To do this, we have to make absolutely sure that no PIOs are in progress
   * so we turn off access to all widgets for the duration of the function.
   *
   * XXX - This code should really check what kind of widget we're talking
   * to.  Bridges can only handle three requests, but XG will do more.
   * How many can crossbow handle to widget 0?  We're assuming 1.
   *
   * XXX - There is a bug in the crossbow that link reset PIOs do not
   * return write responses.  The easiest solution to this problem is to
   * leave widget 0 (xbow) in fire-and-forget mode at all times.  This
   * only affects pio's to xbow registers, which should be rare.
   **/
  static void hub_set_piomode(nasid_t nasid)
  {
  	hubreg_t ii_iowa;
  	hubii_wcr_t ii_wcr;
  	unsigned i;
  
  	ii_iowa = REMOTE_HUB_L(nasid, IIO_OUTWIDGET_ACCESS);
  	REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, 0);
  
  	ii_wcr.wcr_reg_value = REMOTE_HUB_L(nasid, IIO_WCR);
  
  	if (ii_wcr.iwcr_dir_con) {
  		/*
  		 * Assume a bridge here.
  		 */
  		hub_setup_prb(nasid, 0, 3);
  	} else {
  		/*
  		 * Assume a crossbow here.
  		 */
  		hub_setup_prb(nasid, 0, 1);
  	}
  
  	/*
  	 * XXX - Here's where we should take the widget type into
  	 * when account assigning credits.
  	 */
  	for (i = HUB_WIDGET_ID_MIN; i <= HUB_WIDGET_ID_MAX; i++)
  		hub_setup_prb(nasid, i, 3);
  
  	REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, ii_iowa);
  }
  
  /*

   * hub_pio_init  -  PIO-related hub initialization

   *
   * @hub:	hubinfo structure for our hub
   */
  void hub_pio_init(cnodeid_t cnode)
  {
  	nasid_t nasid = COMPACT_TO_NASID_NODEID(cnode);
  	unsigned i;
  
  	/* initialize big window piomaps for this hub */
  	bitmap_zero(hub_data(cnode)->h_bigwin_used, HUB_NUM_BIG_WINDOW);
  	for (i = 0; i < HUB_NUM_BIG_WINDOW; i++)
  		IIO_ITTE_DISABLE(nasid, i);
  
  	hub_set_piomode(nasid);
  }