1/*
  2 * Copyright (C) 1992-1997, 2000-2003 Silicon Graphics, Inc.
  3 * Copyright (C) 2004 Christoph Hellwig.
  4 *	Released under GPL v2.
  5 *
  6 * Support functions for the HUB ASIC - mostly PIO mapping related.
  7 */
  8
  9#include <linux/bitops.h>
 10#include <linux/string.h>
 11#include <linux/mmzone.h>
 12#include <asm/sn/addrs.h>
 13#include <asm/sn/arch.h>
 14#include <asm/sn/hub.h>
 15
 16
 17static int force_fire_and_forget = 1;
 18
 19/**
 20 * hub_pio_map	-  establish a HUB PIO mapping
 21 *
 22 * @hub:	hub to perform PIO mapping on
 23 * @widget:	widget ID to perform PIO mapping for
 24 * @xtalk_addr: xtalk_address that needs to be mapped
 25 * @size:	size of the PIO mapping
 26 *
 27 **/
 28unsigned long hub_pio_map(cnodeid_t cnode, xwidgetnum_t widget,
 29			  unsigned long xtalk_addr, size_t size)
 30{
 31	nasid_t nasid = COMPACT_TO_NASID_NODEID(cnode);
 32	unsigned i;
 33
 34	/* use small-window mapping if possible */
 35	if ((xtalk_addr % SWIN_SIZE) + size <= SWIN_SIZE)
 36		return NODE_SWIN_BASE(nasid, widget) + (xtalk_addr % SWIN_SIZE);
 37
 38	if ((xtalk_addr % BWIN_SIZE) + size > BWIN_SIZE) {
 39		printk(KERN_WARNING "PIO mapping at hub %d widget %d addr 0x%lx"
 40				" too big (%ld)\n",
 41				nasid, widget, xtalk_addr, size);
 42		return 0;
 43	}
 44
 45	xtalk_addr &= ~(BWIN_SIZE-1);
 46	for (i = 0; i < HUB_NUM_BIG_WINDOW; i++) {
 47		if (test_and_set_bit(i, hub_data(cnode)->h_bigwin_used))
 48			continue;
 49
 50		/*
 51		 * The code below does a PIO write to setup an ITTE entry.
 52		 *
 53		 * We need to prevent other CPUs from seeing our updated
 54		 * memory shadow of the ITTE (in the piomap) until the ITTE
 55		 * entry is actually set up; otherwise, another CPU might
 56		 * attempt a PIO prematurely.
 57		 *
 58		 * Also, the only way we can know that an entry has been
 59		 * received  by the hub and can be used by future PIO reads/
 60		 * writes is by reading back the ITTE entry after writing it.
 61		 *
 62		 * For these two reasons, we PIO read back the ITTE entry
 63		 * after we write it.
 64		 */
 65		IIO_ITTE_PUT(nasid, i, HUB_PIO_MAP_TO_MEM, widget, xtalk_addr);
 66		(void) HUB_L(IIO_ITTE_GET(nasid, i));
 67
 68		return NODE_BWIN_BASE(nasid, widget) + (xtalk_addr % BWIN_SIZE);
 69	}
 70
 71	printk(KERN_WARNING "unable to establish PIO mapping for at"
 72			" hub %d widget %d addr 0x%lx\n",
 73			nasid, widget, xtalk_addr);
 74	return 0;
 75}
 76
 77
 78/*
 79 * hub_setup_prb(nasid, prbnum, credits, conveyor)
 80 *
 81 *	Put a PRB into fire-and-forget mode if conveyor isn't set.  Otherwise,
 82 *	put it into conveyor belt mode with the specified number of credits.
 83 */
 84static void hub_setup_prb(nasid_t nasid, int prbnum, int credits)
 85{
 86	iprb_t prb;
 87	int prb_offset;
 88
 89	/*
 90	 * Get the current register value.
 91	 */
 92	prb_offset = IIO_IOPRB(prbnum);
 93	prb.iprb_regval = REMOTE_HUB_L(nasid, prb_offset);
 94
 95	/*
 96	 * Clear out some fields.
 97	 */
 98	prb.iprb_ovflow = 1;
 99	prb.iprb_bnakctr = 0;
100	prb.iprb_anakctr = 0;
101
102	/*
103	 * Enable or disable fire-and-forget mode.
104	 */
105	prb.iprb_ff = force_fire_and_forget ? 1 : 0;
106
107	/*
108	 * Set the appropriate number of PIO credits for the widget.
109	 */
110	prb.iprb_xtalkctr = credits;
111
112	/*
113	 * Store the new value to the register.
114	 */
115	REMOTE_HUB_S(nasid, prb_offset, prb.iprb_regval);
116}
117
118/**
119 * hub_set_piomode  -  set pio mode for a given hub
120 *
121 * @nasid:	physical node ID for the hub in question
122 *
123 * Put the hub into either "PIO conveyor belt" mode or "fire-and-forget" mode.
124 * To do this, we have to make absolutely sure that no PIOs are in progress
125 * so we turn off access to all widgets for the duration of the function.
126 *
127 * XXX - This code should really check what kind of widget we're talking
128 * to.	Bridges can only handle three requests, but XG will do more.
129 * How many can crossbow handle to widget 0?  We're assuming 1.
130 *
131 * XXX - There is a bug in the crossbow that link reset PIOs do not
132 * return write responses.  The easiest solution to this problem is to
133 * leave widget 0 (xbow) in fire-and-forget mode at all times.	This
134 * only affects pio's to xbow registers, which should be rare.
135 **/
136static void hub_set_piomode(nasid_t nasid)
137{
138	hubreg_t ii_iowa;
139	hubii_wcr_t ii_wcr;
140	unsigned i;
141
142	ii_iowa = REMOTE_HUB_L(nasid, IIO_OUTWIDGET_ACCESS);
143	REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, 0);
144
145	ii_wcr.wcr_reg_value = REMOTE_HUB_L(nasid, IIO_WCR);
146
147	if (ii_wcr.iwcr_dir_con) {
148		/*
149		 * Assume a bridge here.
150		 */
151		hub_setup_prb(nasid, 0, 3);
152	} else {
153		/*
154		 * Assume a crossbow here.
155		 */
156		hub_setup_prb(nasid, 0, 1);
157	}
158
159	/*
160	 * XXX - Here's where we should take the widget type into
161	 * when account assigning credits.
162	 */
163	for (i = HUB_WIDGET_ID_MIN; i <= HUB_WIDGET_ID_MAX; i++)
164		hub_setup_prb(nasid, i, 3);
165
166	REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, ii_iowa);
167}
168
169/*
170 * hub_pio_init	 -  PIO-related hub initialization
171 *
172 * @hub:	hubinfo structure for our hub
173 */
174void hub_pio_init(cnodeid_t cnode)
175{
176	nasid_t nasid = COMPACT_TO_NASID_NODEID(cnode);
177	unsigned i;
178
179	/* initialize big window piomaps for this hub */
180	bitmap_zero(hub_data(cnode)->h_bigwin_used, HUB_NUM_BIG_WINDOW);
181	for (i = 0; i < HUB_NUM_BIG_WINDOW; i++)
182		IIO_ITTE_DISABLE(nasid, i);
183
184	hub_set_piomode(nasid);
185}