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 cresits 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}
186