drm_atomic.h revision 152909 
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#include <sys/cdefs.h>
33__FBSDID("$FreeBSD: head/sys/dev/drm/drm_atomic.h 152909 2005-11-28 23:13:57Z anholt $");
34
35/* Many of these implementations are rather fake, but good enough. */
36
37typedef u_int32_t atomic_t;
38
39#ifdef __FreeBSD__
40#define atomic_set(p, v)	(*(p) = (v))
41#define atomic_read(p)		(*(p))
42#define atomic_inc(p)		atomic_add_int(p, 1)
43#define atomic_dec(p)		atomic_subtract_int(p, 1)
44#define atomic_add(n, p)	atomic_add_int(p, n)
45#define atomic_sub(n, p)	atomic_subtract_int(p, n)
46#else /* __FreeBSD__ */
47/* FIXME */
48#define atomic_set(p, v)	(*(p) = (v))
49#define atomic_read(p)		(*(p))
50#define atomic_inc(p)		(*(p) += 1)
51#define atomic_dec(p)		(*(p) -= 1)
52#define atomic_add(n, p)	(*(p) += (n))
53#define atomic_sub(n, p)	(*(p) -= (n))
54/* FIXME */
55#define atomic_add_int(p, v)      *(p) += v
56#define atomic_subtract_int(p, v) *(p) -= v
57#define atomic_set_int(p, bits)   *(p) |= (bits)
58#define atomic_clear_int(p, bits) *(p) &= ~(bits)
59#endif /* !__FreeBSD__ */
60
61#if !defined(__FreeBSD_version) || (__FreeBSD_version < 500000)
62#if defined(__i386__)
63/* The extra atomic functions from 5.0 haven't been merged to 4.x */
64static __inline int
65atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
66{
67	int res = exp;
68
69	__asm __volatile (
70	"	lock ;			"
71	"	cmpxchgl %1,%2 ;	"
72	"       setz	%%al ;		"
73	"	movzbl	%%al,%0 ;	"
74	"1:				"
75	"# atomic_cmpset_int"
76	: "+a" (res)			/* 0 (result) */
77	: "r" (src),			/* 1 */
78	  "m" (*(dst))			/* 2 */
79	: "memory");
80
81	return (res);
82}
83#else /* __i386__ */
84static __inline int
85atomic_cmpset_int(__volatile__ int *dst, int old, int new)
86{
87	int s = splhigh();
88	if (*dst==old) {
89		*dst = new;
90		splx(s);
91		return 1;
92	}
93	splx(s);
94	return 0;
95}
96#endif /* !__i386__ */
97#endif /* !__FreeBSD_version || __FreeBSD_version < 500000 */
98
99static __inline atomic_t
100test_and_set_bit(int b, volatile void *p)
101{
102	int s = splhigh();
103	unsigned int m = 1<<b;
104	unsigned int r = *(volatile int *)p & m;
105	*(volatile int *)p |= m;
106	splx(s);
107	return r;
108}
109
110static __inline void
111clear_bit(int b, volatile void *p)
112{
113	atomic_clear_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
114}
115
116static __inline void
117set_bit(int b, volatile void *p)
118{
119	atomic_set_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
120}
121
122static __inline int
123test_bit(int b, volatile void *p)
124{
125	return ((volatile int *)p)[b >> 5] & (1 << (b & 0x1f));
126}
127
128static __inline int
129find_first_zero_bit(volatile void *p, int max)
130{
131	int b;
132	volatile int *ptr = (volatile int *)p;
133
134	for (b = 0; b < max; b += 32) {
135		if (ptr[b >> 5] != ~0) {
136			for (;;) {
137				if ((ptr[b >> 5] & (1 << (b & 0x1f))) == 0)
138					return b;
139				b++;
140			}
141		}
142	}
143	return max;
144}
145