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/agent.h>
15#include <asm/sn/io.h>
16#include <asm/xtalk/xtalk.h>
17
18
19static int force_fire_and_forget = 1;
20
21/**
22 * hub_pio_map	-  establish a HUB PIO mapping
23 *
24 * @hub:	hub to perform PIO mapping on
25 * @widget:	widget ID to perform PIO mapping for
26 * @xtalk_addr: xtalk_address that needs to be mapped
27 * @size:	size of the PIO mapping
28 *
29 **/
30unsigned long hub_pio_map(nasid_t nasid, xwidgetnum_t widget,
31			  unsigned long xtalk_addr, size_t size)
32{
33	unsigned i;
34
35	/* use small-window mapping if possible */
36	if ((xtalk_addr % SWIN_SIZE) + size <= SWIN_SIZE)
37		return NODE_SWIN_BASE(nasid, widget) + (xtalk_addr % SWIN_SIZE);
38
39	if ((xtalk_addr % BWIN_SIZE) + size > BWIN_SIZE) {
40		printk(KERN_WARNING "PIO mapping at hub %d widget %d addr 0x%lx"
41				" too big (%ld)\n",
42				nasid, widget, xtalk_addr, size);
43		return 0;
44	}
45
46	xtalk_addr &= ~(BWIN_SIZE-1);
47	for (i = 0; i < HUB_NUM_BIG_WINDOW; i++) {
48		if (test_and_set_bit(i, hub_data(nasid)->h_bigwin_used))
49			continue;
50
51		/*
52		 * The code below does a PIO write to setup an ITTE entry.
53		 *
54		 * We need to prevent other CPUs from seeing our updated
55		 * memory shadow of the ITTE (in the piomap) until the ITTE
56		 * entry is actually set up; otherwise, another CPU might
57		 * attempt a PIO prematurely.
58		 *
59		 * Also, the only way we can know that an entry has been
60		 * received  by the hub and can be used by future PIO reads/
61		 * writes is by reading back the ITTE entry after writing it.
62		 *
63		 * For these two reasons, we PIO read back the ITTE entry
64		 * after we write it.
65		 */
66		IIO_ITTE_PUT(nasid, i, HUB_PIO_MAP_TO_MEM, widget, xtalk_addr);
67		__raw_readq(IIO_ITTE_GET(nasid, i));
68
69		return NODE_BWIN_BASE(nasid, widget) + (xtalk_addr % BWIN_SIZE);
70	}
71
72	printk(KERN_WARNING "unable to establish PIO mapping for at"
73			" hub %d widget %d addr 0x%lx\n",
74			nasid, widget, xtalk_addr);
75	return 0;
76}
77
78
79/*
80 * hub_setup_prb(nasid, prbnum, credits, conveyor)
81 *
82 *	Put a PRB into fire-and-forget mode if conveyor isn't set.  Otherwise,
83 *	put it into conveyor belt mode with the specified number of credits.
84 */
85static void hub_setup_prb(nasid_t nasid, int prbnum, int credits)
86{
87	union iprb_u prb;
88	int prb_offset;
89
90	/*
91	 * Get the current register value.
92	 */
93	prb_offset = IIO_IOPRB(prbnum);
94	prb.iprb_regval = REMOTE_HUB_L(nasid, prb_offset);
95
96	/*
97	 * Clear out some fields.
98	 */
99	prb.iprb_ovflow = 1;
100	prb.iprb_bnakctr = 0;
101	prb.iprb_anakctr = 0;
102
103	/*
104	 * Enable or disable fire-and-forget mode.
105	 */
106	prb.iprb_ff = force_fire_and_forget ? 1 : 0;
107
108	/*
109	 * Set the appropriate number of PIO credits for the widget.
110	 */
111	prb.iprb_xtalkctr = credits;
112
113	/*
114	 * Store the new value to the register.
115	 */
116	REMOTE_HUB_S(nasid, prb_offset, prb.iprb_regval);
117}
118
119/**
120 * hub_set_piomode  -  set pio mode for a given hub
121 *
122 * @nasid:	physical node ID for the hub in question
123 *
124 * Put the hub into either "PIO conveyor belt" mode or "fire-and-forget" mode.
125 * To do this, we have to make absolutely sure that no PIOs are in progress
126 * so we turn off access to all widgets for the duration of the function.
127 *
128 * XXX - This code should really check what kind of widget we're talking
129 * to.	Bridges can only handle three requests, but XG will do more.
130 * How many can crossbow handle to widget 0?  We're assuming 1.
131 *
132 * XXX - There is a bug in the crossbow that link reset PIOs do not
133 * return write responses.  The easiest solution to this problem is to
134 * leave widget 0 (xbow) in fire-and-forget mode at all times.	This
135 * only affects pio's to xbow registers, which should be rare.
136 **/
137static void hub_set_piomode(nasid_t nasid)
138{
139	u64 ii_iowa;
140	union hubii_wcr_u ii_wcr;
141	unsigned i;
142
143	ii_iowa = REMOTE_HUB_L(nasid, IIO_OUTWIDGET_ACCESS);
144	REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, 0);
145
146	ii_wcr.wcr_reg_value = REMOTE_HUB_L(nasid, IIO_WCR);
147
148	if (ii_wcr.iwcr_dir_con) {
149		/*
150		 * Assume a bridge here.
151		 */
152		hub_setup_prb(nasid, 0, 3);
153	} else {
154		/*
155		 * Assume a crossbow here.
156		 */
157		hub_setup_prb(nasid, 0, 1);
158	}
159
160	/*
161	 * XXX - Here's where we should take the widget type into
162	 * when account assigning credits.
163	 */
164	for (i = HUB_WIDGET_ID_MIN; i <= HUB_WIDGET_ID_MAX; i++)
165		hub_setup_prb(nasid, i, 3);
166
167	REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, ii_iowa);
168}
169
170/*
171 * hub_pio_init	 -  PIO-related hub initialization
172 *
173 * @hub:	hubinfo structure for our hub
174 */
175void hub_pio_init(nasid_t nasid)
176{
177	unsigned i;
178
179	/* initialize big window piomaps for this hub */
180	bitmap_zero(hub_data(nasid)->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