1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 1992-1997, 2000-2003 Silicon Graphics, Inc.
4 * Copyright (C) 2004 Christoph Hellwig.
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
17 static 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 **/
28 unsigned 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 __raw_readq(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 */
84 static 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 **/
136 static void hub_set_piomode(nasid_t nasid)
137 {
138 u64 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 */
174 void 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 }