sys/dev/drm/drm_atomic.h

   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 #define atomic_set(p, v)        (*(p) = (v))
  37 #define atomic_read(p)          (*(p))
  38 #define atomic_inc(p)           atomic_add_int(p, 1)
  39 #define atomic_dec(p)           atomic_subtract_int(p, 1)
  40 #define atomic_add(n, p)        atomic_add_int(p, n)
  41 #define atomic_sub(n, p)        atomic_subtract_int(p, n)
  42
  43 static __inline atomic_t
  44 test_and_set_bit(int b, volatile void *p)
  45 {
  46         unsigned int m = 1<<b;
  47         unsigned int o, n;
  48
  49         do {
  50                 o = *(volatile int *)p;
  51                 n = o | m;
  52         } while (!atomic_cmpset_int(p, o, n));
  53
  54         return (o & m);
  55 }
  56
  57 static __inline void
  58 clear_bit(int b, volatile void *p)
  59 {
  60         atomic_clear_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
  61 }
  62
  63 static __inline void
  64 set_bit(int b, volatile void *p)
  65 {
  66         atomic_set_int(((volatile int *)p) + (b >> 5), 1 << (b & 0x1f));
  67 }
  68
  69 static __inline int
  70 test_bit(int b, volatile void *p)
  71 {
  72         return ((volatile int *)p)[b >> 5] & (1 << (b & 0x1f));
  73 }
  74
  75 static __inline int
  76 find_first_zero_bit(volatile void *p, int max)
  77 {
  78         int b;
  79         volatile int *ptr = (volatile int *)p;
  80
  81         for (b = 0; b < max; b += 32) {
  82                 if (ptr[b >> 5] != ~0) {
  83                         for (;;) {
  84                                 if ((ptr[b >> 5] & (1 << (b & 0x1f))) == 0)
  85                                         return b;
  86                                 b++;
  87                         }
  88                 }
  89         }
  90         return max;
  91 }