1 /* $NetBSD: gbus_io.c,v 1.1 2024/03/06 05:33:09 thorpej Exp $ */
2
3 /*-
4 * Copyright (c) 2024 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*
33 * Bus space implementation for the Gbus: a general 8-bit bus found
34 * on Laser / TurboLaser CPU modules.
35 */
36
37 #include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
38
39 __KERNEL_RCSID(0, "$NetBSD: gbus_io.c,v 1.1 2024/03/06 05:33:09 thorpej Exp $");
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/device.h>
44 #include <sys/endian.h>
45 #include <sys/vmem.h>
46
47 #include <sys/bus.h>
48
49 #include <alpha/gbus/gbusvar.h>
50
51 /*
52 * While physically there is one Gbus per CPU module on the system,
53 * logically there is only one (the one on the CPU module that holds
54 * the primary CPU), and this describes it.
55 */
56 static struct gbus_config {
57 paddr_t gc_sysbase; /* system base address of Gbus */
58 struct alpha_bus_space gc_st; /* the Gbus's space tag */
59 } gbus_config;
60
61 /* Adjacent bytes on the Gbus are spaced 64 bytes apart. */
62 #define GBUS_ADDR_SHIFT 6
63
64 static int
gbus_io_map(void * v,bus_addr_t addr,bus_size_t size __unused,int flags __unused,bus_space_handle_t * iohp,int acct __unused)65 gbus_io_map(
66 void *v,
67 bus_addr_t addr,
68 bus_size_t size __unused,
69 int flags __unused,
70 bus_space_handle_t *iohp,
71 int acct __unused)
72 {
73 struct gbus_config * const gc = v;
74
75 *iohp = ALPHA_PHYS_TO_K0SEG(gc->gc_sysbase + addr);
76
77 return 0;
78 }
79
80 static void
gbus_io_unmap(void * v __unused,bus_space_handle_t ioh __unused,bus_size_t size __unused,int acct __unused)81 gbus_io_unmap(
82 void *v __unused,
83 bus_space_handle_t ioh __unused,
84 bus_size_t size __unused,
85 int acct __unused)
86 {
87 /* No work to do. */
88 }
89
90 static void
gbus_io_barrier(void * v __unused,bus_space_handle_t ioh __unused,bus_size_t off __unused,bus_size_t len __unused,int flags __unused)91 gbus_io_barrier(
92 void *v __unused,
93 bus_space_handle_t ioh __unused,
94 bus_size_t off __unused,
95 bus_size_t len __unused,
96 int flags __unused)
97 {
98 if (flags & BUS_SPACE_BARRIER_READ) {
99 alpha_mb();
100 } else if (flags & BUS_SPACE_BARRIER_WRITE) {
101 alpha_wmb();
102 }
103 }
104
105 __CTASSERT(_BYTE_ORDER == _LITTLE_ENDIAN);
106
107 /*
108 * A 32-bit pointer is used here because the bus transaction is going to
109 * be 32-bit regardless, and this avoids having the compiler generate
110 * extbl / insbl / mskbl unnecessarily (or r/m/w in the write case).
111 */
112 #define GBUS_ADDR(ioh, off) \
113 (uint32_t *)((ioh) + ((off) << GBUS_ADDR_SHIFT))
114
115 static uint8_t
gbus_io_read_1(void * v __unused,bus_space_handle_t ioh,bus_size_t off)116 gbus_io_read_1(
117 void *v __unused,
118 bus_space_handle_t ioh,
119 bus_size_t off)
120 {
121 uint32_t *addr = GBUS_ADDR(ioh, off);
122
123 alpha_mb();
124 return (uint8_t)atomic_load_relaxed(addr);
125 }
126
127 static void
gbus_io_write_1(void * v __unused,bus_space_handle_t ioh,bus_size_t off,uint8_t val)128 gbus_io_write_1(
129 void *v __unused,
130 bus_space_handle_t ioh,
131 bus_size_t off,
132 uint8_t val)
133 {
134 uint32_t *addr = GBUS_ADDR(ioh, off);
135
136 atomic_store_relaxed(addr, (uint32_t)val);
137 alpha_mb();
138 }
139
140 bus_space_tag_t
gbus_io_init(paddr_t sysbase)141 gbus_io_init(paddr_t sysbase)
142 {
143 struct gbus_config * const gc = &gbus_config;
144 bus_space_tag_t t = &gc->gc_st;
145
146 if (t->abs_cookie == gc) {
147 /* Already initialized. */
148 KASSERT(gc->gc_sysbase == sysbase);
149 return t;
150 }
151
152 gc->gc_sysbase = sysbase;
153 memset(t, 0, sizeof(*t));
154
155 /*
156 * Initialize the bus space tag. We just support the bare
157 * minimum operations required by Gbus devices.
158 */
159
160 /* cookie */
161 t->abs_cookie = gc;
162
163 /* mapping/unmapping */
164 t->abs_map = gbus_io_map;
165 t->abs_unmap = gbus_io_unmap;
166
167 /* barrier */
168 t->abs_barrier = gbus_io_barrier;
169
170 /* read (single) */
171 t->abs_r_1 = gbus_io_read_1;
172
173 /* write (single) */
174 t->abs_w_1 = gbus_io_write_1;
175
176 return t;
177 }
178