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Linux/arch/arm/include/asm/bitops.h

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  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 */
352 

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