xref: /openbmc/linux/arch/mips/sgi-ip27/ip27-hubio.c (revision db96e058)
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 
19 static 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  **/
hub_pio_map(nasid_t nasid,xwidgetnum_t widget,unsigned long xtalk_addr,size_t size)30 unsigned 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  */
hub_setup_prb(nasid_t nasid,int prbnum,int credits)85 static 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  **/
hub_set_piomode(nasid_t nasid)137 static 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  */
hub_pio_init(nasid_t nasid)175 void 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