arch/arm/include/asm/bitops.h

   1 /*
   2  * Copyright 1995, Russell King.
   3  * Various bits and pieces copyrights include:
   4  *  Linus Torvalds (test_bit).
   5  * Big endian support: Copyright 2001, Nicolas Pitre
   6  *  reworked by rmk.
   7  *
   8  * bit 0 is the LSB of an "unsigned long" quantity.
   9  *
  10  * Please note that the code in this file should never be included
  11  * from user space.  Many of these are not implemented in assembler
  12  * since they would be too costly.  Also, they require privileged
  13  * instructions (which are not available from user mode) to ensure
  14  * that they are atomic.
  15  */
  16
  17 #ifndef __ASM_ARM_BITOPS_H
  18 #define __ASM_ARM_BITOPS_H
  19
  20 #ifdef __KERNEL__
  21
  22 #ifndef _LINUX_BITOPS_H
  23 #error only <linux/bitops.h> can be included directly
  24 #endif
  25
  26 #include <linux/compiler.h>
  27 #include <asm/system.h>
  28
  29 #define smp_mb__before_clear_bit()      smp_mb()
  30 #define smp_mb__after_clear_bit()       smp_mb()
  31
  32 /*
  33  * These functions are the basis of our bit ops.
  34  *
  35  * First, the atomic bitops. These use native endian.
  36  */
  37 static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
  38 {
  39         unsigned long flags;
  40         unsigned long mask = 1UL << (bit & 31);
  41
  42         p += bit >> 5;
  43
  44         raw_local_irq_save(flags);
  45         *p |= mask;
  46         raw_local_irq_restore(flags);
  47 }
  48
  49 static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
  50 {
  51         unsigned long flags;
  52         unsigned long mask = 1UL << (bit & 31);
  53
  54         p += bit >> 5;
  55
  56         raw_local_irq_save(flags);
  57         *p &= ~mask;
  58         raw_local_irq_restore(flags);
  59 }
  60
  61 static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
  62 {
  63         unsigned long flags;
  64         unsigned long mask = 1UL << (bit & 31);
  65
  66         p += bit >> 5;
  67
  68         raw_local_irq_save(flags);
  69         *p ^= mask;
  70         raw_local_irq_restore(flags);
  71 }
  72
  73 static inline int
  74 ____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
  75 {
  76         unsigned long flags;
  77         unsigned int res;
  78         unsigned long mask = 1UL << (bit & 31);
  79
  80         p += bit >> 5;
  81
  82         raw_local_irq_save(flags);
  83         res = *p;
  84         *p = res | mask;
  85         raw_local_irq_restore(flags);
  86
  87         return (res & mask) != 0;
  88 }
  89
  90 static inline int
  91 ____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
  92 {
  93         unsigned long flags;
  94         unsigned int res;
  95         unsigned long mask = 1UL << (bit & 31);
  96
  97         p += bit >> 5;
  98
  99         raw_local_irq_save(flags);
 100         res = *p;
 101         *p = res & ~mask;
 102         raw_local_irq_restore(flags);
 103
 104         return (res & mask) != 0;
 105 }
 106
 107 static inline int
 108 ____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
 109 {
 110         unsigned long flags;
 111         unsigned int res;
 112         unsigned long mask = 1UL << (bit & 31);
 113
 114         p += bit >> 5;
 115
 116         raw_local_irq_save(flags);
 117         res = *p;
 118         *p = res ^ mask;
 119         raw_local_irq_restore(flags);
 120
 121         return (res & mask) != 0;
 122 }
 123
 124 #include <asm-generic/bitops/non-atomic.h>
 125
 126 /*
 127  *  A note about Endian-ness.
 128  *  -------------------------
 129  *
 130  * When the ARM is put into big endian mode via CR15, the processor
 131  * merely swaps the order of bytes within words, thus:
 132  *
 133  *          ------------ physical data bus bits -----------
 134  *          D31 ... D24  D23 ... D16  D15 ... D8  D7 ... D0
 135  * little     byte 3       byte 2       byte 1      byte 0
 136  * big        byte 0       byte 1       byte 2      byte 3
 137  *
 138  * This means that reading a 32-bit word at address 0 returns the same
 139  * value irrespective of the endian mode bit.
 140  *
 141  * Peripheral devices should be connected with the data bus reversed in
 142  * "Big Endian" mode.  ARM Application Note 61 is applicable, and is
 143  * available from http://www.arm.com/.
 144  *
 145  * The following assumes that the data bus connectivity for big endian
 146  * mode has been followed.
 147  *
 148  * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
 149  */
 150
 151 /*
 152  * Native endian assembly bitops.  nr = 0 -> word 0 bit 0.
 153  */
 154 extern void _set_bit(int nr, volatile unsigned long * p);
 155 extern void _clear_bit(int nr, volatile unsigned long * p);
 156 extern void _change_bit(int nr, volatile unsigned long * p);
 157 extern int _test_and_set_bit(int nr, volatile unsigned long * p);
 158 extern int _test_and_clear_bit(int nr, volatile unsigned long * p);
 159 extern int _test_and_change_bit(int nr, volatile unsigned long * p);
 160
 161 /*
 162  * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
 163  */
 164 extern int _find_first_zero_bit_le(const void * p, unsigned size);
 165 extern int _find_next_zero_bit_le(const void * p, int size, int offset);
 166 extern int _find_first_bit_le(const unsigned long *p, unsigned size);
 167 extern int _find_next_bit_le(const unsigned long *p, int size, int offset);
 168
 169 /*
 170  * Big endian assembly bitops.  nr = 0 -> byte 3 bit 0.
 171  */
 172 extern int _find_first_zero_bit_be(const void * p, unsigned size);
 173 extern int _find_next_zero_bit_be(const void * p, int size, int offset);
 174 extern int _find_first_bit_be(const unsigned long *p, unsigned size);
 175 extern int _find_next_bit_be(const unsigned long *p, int size, int offset);
 176
 177 #ifndef CONFIG_SMP
 178 /*
 179  * The __* form of bitops are non-atomic and may be reordered.
 180  */
 181 #define ATOMIC_BITOP(name,nr,p)                 \
 182         (__builtin_constant_p(nr) ? ____atomic_##name(nr, p) : _##name(nr,p))
 183 #else
 184 #define ATOMIC_BITOP(name,nr,p)         _##name(nr,p)
 185 #endif
 186
 187 /*
 188  * Native endian atomic definitions.
 189  */
 190 #define set_bit(nr,p)                   ATOMIC_BITOP(set_bit,nr,p)
 191 #define clear_bit(nr,p)                 ATOMIC_BITOP(clear_bit,nr,p)
 192 #define change_bit(nr,p)                ATOMIC_BITOP(change_bit,nr,p)
 193 #define test_and_set_bit(nr,p)          ATOMIC_BITOP(test_and_set_bit,nr,p)
 194 #define test_and_clear_bit(nr,p)        ATOMIC_BITOP(test_and_clear_bit,nr,p)
 195 #define test_and_change_bit(nr,p)       ATOMIC_BITOP(test_and_change_bit,nr,p)
 196
 197 #ifndef __ARMEB__
 198 /*
 199  * These are the little endian, atomic definitions.
 200  */
 201 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_le(p,sz)
 202 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_le(p,sz,off)
 203 #define find_first_bit(p,sz)            _find_first_bit_le(p,sz)
 204 #define find_next_bit(p,sz,off)         _find_next_bit_le(p,sz,off)
 205
 206 #else
 207 /*
 208  * These are the big endian, atomic definitions.
 209  */
 210 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_be(p,sz)
 211 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_be(p,sz,off)
 212 #define find_first_bit(p,sz)            _find_first_bit_be(p,sz)
 213 #define find_next_bit(p,sz,off)         _find_next_bit_be(p,sz,off)
 214
 215 #endif
 216
 217 #if __LINUX_ARM_ARCH__ < 5
 218
 219 #include <asm-generic/bitops/ffz.h>
 220 #include <asm-generic/bitops/__fls.h>
 221 #include <asm-generic/bitops/__ffs.h>
 222 #include <asm-generic/bitops/fls.h>
 223 #include <asm-generic/bitops/ffs.h>
 224
 225 #else
 226
 227 static inline int constant_fls(int x)
 228 {
 229         int r = 32;
 230
 231         if (!x)
 232                 return 0;
 233         if (!(x & 0xffff0000u)) {
 234                 x <<= 16;
 235                 r -= 16;
 236         }
 237         if (!(x & 0xff000000u)) {
 238                 x <<= 8;
 239                 r -= 8;
 240         }
 241         if (!(x & 0xf0000000u)) {
 242                 x <<= 4;
 243                 r -= 4;
 244         }
 245         if (!(x & 0xc0000000u)) {
 246                 x <<= 2;
 247                 r -= 2;
 248         }
 249         if (!(x & 0x80000000u)) {
 250                 x <<= 1;
 251                 r -= 1;
 252         }
 253         return r;
 254 }
 255
 256 /*
 257  * On ARMv5 and above those functions can be implemented around
 258  * the clz instruction for much better code efficiency.
 259  */
 260
 261 static inline int fls(int x)
 262 {
 263         int ret;
 264
 265         if (__builtin_constant_p(x))
 266                return constant_fls(x);
 267
 268         asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
 269         ret = 32 - ret;
 270         return ret;
 271 }
 272
 273 #define __fls(x) (fls(x) - 1)
 274 #define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); })
 275 #define __ffs(x) (ffs(x) - 1)
 276 #define ffz(x) __ffs( ~(x) )
 277
 278 #endif
 279
 280 #include <asm-generic/bitops/fls64.h>
 281
 282 #include <asm-generic/bitops/sched.h>
 283 #include <asm-generic/bitops/hweight.h>
 284 #include <asm-generic/bitops/lock.h>
 285
 286 #ifdef __ARMEB__
 287
 288 static inline int find_first_zero_bit_le(const void *p, unsigned size)
 289 {
 290         return _find_first_zero_bit_le(p, size);
 291 }
 292 #define find_first_zero_bit_le find_first_zero_bit_le
 293
 294 static inline int find_next_zero_bit_le(const void *p, int size, int offset)
 295 {
 296         return _find_next_zero_bit_le(p, size, offset);
 297 }
 298 #define find_next_zero_bit_le find_next_zero_bit_le
 299
 300 static inline int find_next_bit_le(const void *p, int size, int offset)
 301 {
 302         return _find_next_bit_le(p, size, offset);
 303 }
 304 #define find_next_bit_le find_next_bit_le
 305
 306 #endif
 307
 308 #include <asm-generic/bitops/le.h>
 309
 310 /*
 311  * Ext2 is defined to use little-endian byte ordering.
 312  */
 313 #include <asm-generic/bitops/ext2-atomic-setbit.h>
 314
 315 #endif /* __KERNEL__ */
 316
 317 #endif /* _ARM_BITOPS_H */