arch/arm/include/asm/bitops.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright 1995, Russell King.
   4  * Various bits and pieces copyrights include:
   5  *  Linus Torvalds (test_bit).
   6  * Big endian support: Copyright 2001, Nicolas Pitre
   7  *  reworked by rmk.
   8  *
   9  * bit 0 is the LSB of an "unsigned long" quantity.
  10  *
  11  * Please note that the code in this file should never be included
  12  * from user space.  Many of these are not implemented in assembler
  13  * since they would be too costly.  Also, they require privileged
  14  * instructions (which are not available from user mode) to ensure
  15  * that they are atomic.
  16  */
  17
  18 #ifndef __ASM_ARM_BITOPS_H
  19 #define __ASM_ARM_BITOPS_H
  20
  21 #ifdef __KERNEL__
  22
  23 #ifndef _LINUX_BITOPS_H
  24 #error only <linux/bitops.h> can be included directly
  25 #endif
  26
  27 #include <linux/compiler.h>
  28 #include <linux/irqflags.h>
  29 #include <asm/barrier.h>
  30
  31 /*
  32  * These functions are the basis of our bit ops.
  33  *
  34  * First, the atomic bitops. These use native endian.
  35  */
  36 static inline void ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
  37 {
  38         unsigned long flags;
  39         unsigned long mask = BIT_MASK(bit);
  40
  41         p += BIT_WORD(bit);
  42
  43         raw_local_irq_save(flags);
  44         *p |= mask;
  45         raw_local_irq_restore(flags);
  46 }
  47
  48 static inline void ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
  49 {
  50         unsigned long flags;
  51         unsigned long mask = BIT_MASK(bit);
  52
  53         p += BIT_WORD(bit);
  54
  55         raw_local_irq_save(flags);
  56         *p &= ~mask;
  57         raw_local_irq_restore(flags);
  58 }
  59
  60 static inline void ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
  61 {
  62         unsigned long flags;
  63         unsigned long mask = BIT_MASK(bit);
  64
  65         p += BIT_WORD(bit);
  66
  67         raw_local_irq_save(flags);
  68         *p ^= mask;
  69         raw_local_irq_restore(flags);
  70 }
  71
  72 static inline int
  73 ____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
  74 {
  75         unsigned long flags;
  76         unsigned int res;
  77         unsigned long mask = BIT_MASK(bit);
  78
  79         p += BIT_WORD(bit);
  80
  81         raw_local_irq_save(flags);
  82         res = *p;
  83         *p = res | mask;
  84         raw_local_irq_restore(flags);
  85
  86         return (res & mask) != 0;
  87 }
  88
  89 static inline int
  90 ____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
  91 {
  92         unsigned long flags;
  93         unsigned int res;
  94         unsigned long mask = BIT_MASK(bit);
  95
  96         p += BIT_WORD(bit);
  97
  98         raw_local_irq_save(flags);
  99         res = *p;
 100         *p = res & ~mask;
 101         raw_local_irq_restore(flags);
 102
 103         return (res & mask) != 0;
 104 }
 105
 106 static inline int
 107 ____atomic_test_and_change_bit(unsigned int bit, volatile unsigned long *p)
 108 {
 109         unsigned long flags;
 110         unsigned int res;
 111         unsigned long mask = BIT_MASK(bit);
 112
 113         p += BIT_WORD(bit);
 114
 115         raw_local_irq_save(flags);
 116         res = *p;
 117         *p = res ^ mask;
 118         raw_local_irq_restore(flags);
 119
 120         return (res & mask) != 0;
 121 }
 122
 123 #include <asm-generic/bitops/non-atomic.h>
 124
 125 /*
 126  *  A note about Endian-ness.
 127  *  -------------------------
 128  *
 129  * When the ARM is put into big endian mode via CR15, the processor
 130  * merely swaps the order of bytes within words, thus:
 131  *
 132  *          ------------ physical data bus bits -----------
 133  *          D31 ... D24  D23 ... D16  D15 ... D8  D7 ... D0
 134  * little     byte 3       byte 2       byte 1      byte 0
 135  * big        byte 0       byte 1       byte 2      byte 3
 136  *
 137  * This means that reading a 32-bit word at address 0 returns the same
 138  * value irrespective of the endian mode bit.
 139  *
 140  * Peripheral devices should be connected with the data bus reversed in
 141  * "Big Endian" mode.  ARM Application Note 61 is applicable, and is
 142  * available from http://www.arm.com/.
 143  *
 144  * The following assumes that the data bus connectivity for big endian
 145  * mode has been followed.
 146  *
 147  * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
 148  */
 149
 150 /*
 151  * Native endian assembly bitops.  nr = 0 -> word 0 bit 0.
 152  */
 153 extern void _set_bit(int nr, volatile unsigned long * p);
 154 extern void _clear_bit(int nr, volatile unsigned long * p);
 155 extern void _change_bit(int nr, volatile unsigned long * p);
 156 extern int _test_and_set_bit(int nr, volatile unsigned long * p);
 157 extern int _test_and_clear_bit(int nr, volatile unsigned long * p);
 158 extern int _test_and_change_bit(int nr, volatile unsigned long * p);
 159
 160 /*
 161  * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
 162  */
 163 extern int _find_first_zero_bit_le(const unsigned long *p, unsigned size);
 164 extern int _find_next_zero_bit_le(const unsigned long *p, int size, int offset);
 165 extern int _find_first_bit_le(const unsigned long *p, unsigned size);
 166 extern int _find_next_bit_le(const unsigned long *p, int size, int offset);
 167
 168 /*
 169  * Big endian assembly bitops.  nr = 0 -> byte 3 bit 0.
 170  */
 171 extern int _find_first_zero_bit_be(const unsigned long *p, unsigned size);
 172 extern int _find_next_zero_bit_be(const unsigned long *p, int size, int offset);
 173 extern int _find_first_bit_be(const unsigned long *p, unsigned size);
 174 extern int _find_next_bit_be(const unsigned long *p, int size, int offset);
 175
 176 #ifndef CONFIG_SMP
 177 /*
 178  * The __* form of bitops are non-atomic and may be reordered.
 179  */
 180 #define ATOMIC_BITOP(name,nr,p)                 \
 181         (__builtin_constant_p(nr) ? ____atomic_##name(nr, p) : _##name(nr,p))
 182 #else
 183 #define ATOMIC_BITOP(name,nr,p)         _##name(nr,p)
 184 #endif
 185
 186 /*
 187  * Native endian atomic definitions.
 188  */
 189 #define set_bit(nr,p)                   ATOMIC_BITOP(set_bit,nr,p)
 190 #define clear_bit(nr,p)                 ATOMIC_BITOP(clear_bit,nr,p)
 191 #define change_bit(nr,p)                ATOMIC_BITOP(change_bit,nr,p)
 192 #define test_and_set_bit(nr,p)          ATOMIC_BITOP(test_and_set_bit,nr,p)
 193 #define test_and_clear_bit(nr,p)        ATOMIC_BITOP(test_and_clear_bit,nr,p)
 194 #define test_and_change_bit(nr,p)       ATOMIC_BITOP(test_and_change_bit,nr,p)
 195
 196 #ifndef __ARMEB__
 197 /*
 198  * These are the little endian, atomic definitions.
 199  */
 200 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_le(p,sz)
 201 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_le(p,sz,off)
 202 #define find_first_bit(p,sz)            _find_first_bit_le(p,sz)
 203 #define find_next_bit(p,sz,off)         _find_next_bit_le(p,sz,off)
 204
 205 #else
 206 /*
 207  * These are the big endian, atomic definitions.
 208  */
 209 #define find_first_zero_bit(p,sz)       _find_first_zero_bit_be(p,sz)
 210 #define find_next_zero_bit(p,sz,off)    _find_next_zero_bit_be(p,sz,off)
 211 #define find_first_bit(p,sz)            _find_first_bit_be(p,sz)
 212 #define find_next_bit(p,sz,off)         _find_next_bit_be(p,sz,off)
 213
 214 #endif
 215
 216 #if __LINUX_ARM_ARCH__ < 5
 217
 218 #include <asm-generic/bitops/ffz.h>
 219 #include <asm-generic/bitops/__fls.h>
 220 #include <asm-generic/bitops/__ffs.h>
 221 #include <asm-generic/bitops/fls.h>
 222 #include <asm-generic/bitops/ffs.h>
 223
 224 #else
 225
 226 static inline int constant_fls(int x)
 227 {
 228         int r = 32;
 229
 230         if (!x)
 231                 return 0;
 232         if (!(x & 0xffff0000u)) {
 233                 x <<= 16;
 234                 r -= 16;
 235         }
 236         if (!(x & 0xff000000u)) {
 237                 x <<= 8;
 238                 r -= 8;
 239         }
 240         if (!(x & 0xf0000000u)) {
 241                 x <<= 4;
 242                 r -= 4;
 243         }
 244         if (!(x & 0xc0000000u)) {
 245                 x <<= 2;
 246                 r -= 2;
 247         }
 248         if (!(x & 0x80000000u)) {
 249                 x <<= 1;
 250                 r -= 1;
 251         }
 252         return r;
 253 }
 254
 255 /*
 256  * On ARMv5 and above those functions can be implemented around the
 257  * clz instruction for much better code efficiency.  __clz returns
 258  * the number of leading zeros, zero input will return 32, and
 259  * 0x80000000 will return 0.
 260  */
 261 static inline unsigned int __clz(unsigned int x)
 262 {
 263         unsigned int ret;
 264
 265         asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
 266
 267         return ret;
 268 }
 269
 270 /*
 271  * fls() returns zero if the input is zero, otherwise returns the bit
 272  * position of the last set bit, where the LSB is 1 and MSB is 32.
 273  */
 274 static inline int fls(int x)
 275 {
 276         if (__builtin_constant_p(x))
 277                return constant_fls(x);
 278
 279         return 32 - __clz(x);
 280 }
 281
 282 /*
 283  * __fls() returns the bit position of the last bit set, where the
 284  * LSB is 0 and MSB is 31.  Zero input is undefined.
 285  */
 286 static inline unsigned long __fls(unsigned long x)
 287 {
 288         return fls(x) - 1;
 289 }
 290
 291 /*
 292  * ffs() returns zero if the input was zero, otherwise returns the bit
 293  * position of the first set bit, where the LSB is 1 and MSB is 32.
 294  */
 295 static inline int ffs(int x)
 296 {
 297         return fls(x & -x);
 298 }
 299
 300 /*
 301  * __ffs() returns the bit position of the first bit set, where the
 302  * LSB is 0 and MSB is 31.  Zero input is undefined.
 303  */
 304 static inline unsigned long __ffs(unsigned long x)
 305 {
 306         return ffs(x) - 1;
 307 }
 308
 309 #define ffz(x) __ffs( ~(x) )
 310
 311 #endif
 312
 313 #include <asm-generic/bitops/fls64.h>
 314
 315 #include <asm-generic/bitops/sched.h>
 316 #include <asm-generic/bitops/hweight.h>
 317 #include <asm-generic/bitops/lock.h>
 318
 319 #ifdef __ARMEB__
 320
 321 static inline int find_first_zero_bit_le(const void *p, unsigned size)
 322 {
 323         return _find_first_zero_bit_le(p, size);
 324 }
 325 #define find_first_zero_bit_le find_first_zero_bit_le
 326
 327 static inline int find_next_zero_bit_le(const void *p, int size, int offset)
 328 {
 329         return _find_next_zero_bit_le(p, size, offset);
 330 }
 331 #define find_next_zero_bit_le find_next_zero_bit_le
 332
 333 static inline int find_next_bit_le(const void *p, int size, int offset)
 334 {
 335         return _find_next_bit_le(p, size, offset);
 336 }
 337 #define find_next_bit_le find_next_bit_le
 338
 339 #endif
 340
 341 #include <asm-generic/bitops/find.h>
 342 #include <asm-generic/bitops/le.h>
 343
 344 /*
 345  * Ext2 is defined to use little-endian byte ordering.
 346  */
 347 #include <asm-generic/bitops/ext2-atomic-setbit.h>
 348
 349 #endif /* __KERNEL__ */
 350
 351 #endif /* _ARM_BITOPS_H */