1 /**
2 * \file drm_atomic.h
3 * Atomic operations used in the DRM which may or may not be provided by the OS.
4 *
5 * \author Eric Anholt <anholt@FreeBSD.org>
6 */
7
8 /*-
9 * Copyright 2004 Eric Anholt
10 * All Rights Reserved.
11 *
12 * Permission is hereby granted, free of charge, to any person obtaining a
13 * copy of this software and associated documentation files (the "Software"),
14 * to deal in the Software without restriction, including without limitation
15 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
16 * and/or sell copies of the Software, and to permit persons to whom the
17 * Software is furnished to do so, subject to the following conditions:
18 *
19 * The above copyright notice and this permission notice (including the next
20 * paragraph) shall be included in all copies or substantial portions of the
21 * Software.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
25 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
26 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
27 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
28 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
29 * OTHER DEALINGS IN THE SOFTWARE.
30 */
31
32 /* Many of these implementations are rather fake, but good enough. */
33
34 typedef u_int32_t atomic_t;
35
36 #if defined(__FreeBSD__)
37 #define atomic_set(p, v) (*(p) = (v))
38 #define atomic_read(p) (*(p))
39 #define atomic_inc(p) atomic_add_int(p, 1)
40 #define atomic_dec(p) atomic_subtract_int(p, 1)
41 #define atomic_add(n, p) atomic_add_int(p, n)
42 #define atomic_sub(n, p) atomic_subtract_int(p, n)
43
44 static __inline atomic_t
test_and_set_bit(int b,volatile void * p)45 test_and_set_bit(int b, volatile void *p)
46 {
47 int s = splhigh();
48 unsigned int m = 1<<b;
49 unsigned int r = *(volatile int *)p & m;
50 *(volatile int *)p |= m;
51 splx(s);
52 return !!r;
53 }
54
55 static __inline void
clear_bit(int b,volatile void * p)56 clear_bit(int b, volatile void *p)
57 {
58 atomic_clear_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
59 }
60
61 static __inline void
set_bit(int b,volatile void * p)62 set_bit(int b, volatile void *p)
63 {
64 atomic_set_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
65 }
66
67 static __inline int
test_bit(int b,volatile void * p)68 test_bit(int b, volatile void *p)
69 {
70 return ((volatile int *)p)[b >> 5] & (1 << (b & 0x1f));
71 }
72
73 #elif defined(__NetBSD__)
74
75 #include <sys/atomic.h>
76
77 #define atomic_set(p, v) (*((volatile uint32_t *)p) = (v))
78 #define atomic_read(p) (*(p))
79 #define atomic_inc(p) atomic_inc_uint(p)
80 #define atomic_dec(p) atomic_dec_uint(p)
81 #define atomic_add(n, p) atomic_add_int(p, n)
82 #define atomic_sub(n, p) atomic_add_int(p, -(n))
83
84 #define atomic_add_acq_int(p, v) atomic_add(v, p)
85 #define atomic_subtract_acq_int(p, v) atomic_sub(v, p)
86 #define atomic_set_int(p, bits) atomic_or_uint(p, bits)
87 #define atomic_clear_int(p, bits) atomic_and_uint(p, ~(bits))
88
89 #define atomic_cmpset_int(p, o, n) \
90 ((old == atomic_cas_uint(p, o, n)) ? 1 : 0)
91
92 #define set_bit(b, p) \
93 atomic_set_int(((volatile uint32_t *)(volatile void *)p) + (b >> 5),\
94 (1 << (b & 0x1f)))
95
96 #define clear_bit(b, p) \
97 atomic_clear_int(((volatile uint32_t *)(volatile void *)p) + (b >> 5), \
98 (1 << (b & 0x1f)))
99
100 #define test_bit(b, p) \
101 (((volatile uint32_t *)(volatile void *)p)[b >> 5] & (1 << (b & 0x1f)))
102
103 static __inline uint32_t
test_and_set_bit(int b,volatile void * p)104 test_and_set_bit(int b, volatile void *p)
105 {
106 volatile uint32_t *val;
107 uint32_t mask, old;
108
109 val = (volatile uint32_t *)p;
110 mask = 1 << b;
111
112 do {
113 old = *val;
114 if ((old & mask) != 0)
115 break;
116 } while (atomic_cas_uint(val, old, old | mask) != old);
117
118 return !!(old & mask);
119 }
120
121 #endif
122 static __inline int
find_first_zero_bit(volatile void * p,int max_)123 find_first_zero_bit(volatile void *p, int max_)
124 {
125 int b;
126 volatile int *ptr = (volatile int *)p;
127
128 for (b = 0; b < max_; b += 32) {
129 if (ptr[b >> 5] != ~0) {
130 for (;;) {
131 if ((ptr[b >> 5] & (1 << (b & 0x1f))) == 0)
132 return b;
133 b++;
134 }
135 }
136 }
137 return max_;
138 }
139