1 /* SPDX-License-Identifier: GPL-2.0 */ !! 1 #ifdef __KERNEL__
2 #ifndef __ASM_GENERIC_DELAY_H !! 2 #ifndef _PPC_DELAY_H
3 #define __ASM_GENERIC_DELAY_H !! 3 #define _PPC_DELAY_H
4 !! 4
5 /* Undefined functions to get compile-time err !! 5 #include <asm/param.h>
6 extern void __bad_udelay(void); !! 6
7 extern void __bad_ndelay(void); !! 7 /*
8 !! 8 * Copyright 1996, Paul Mackerras.
9 extern void __udelay(unsigned long usecs); !! 9 *
10 extern void __ndelay(unsigned long nsecs); !! 10 * This program is free software; you can redistribute it and/or
11 extern void __const_udelay(unsigned long xloop !! 11 * modify it under the terms of the GNU General Public License
12 extern void __delay(unsigned long loops); !! 12 * as published by the Free Software Foundation; either version
>> 13 * 2 of the License, or (at your option) any later version.
>> 14 */
>> 15
>> 16 extern unsigned long loops_per_jiffy;
>> 17
>> 18 extern void __delay(unsigned int loops);
13 19
14 /* 20 /*
15 * The weird n/20000 thing suppresses a "compa !! 21 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
16 * limited range of data type" warning with no !! 22 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
>> 23 *
>> 24 * The mulhwu instruction gives us loops = (a * b) / 2^32.
>> 25 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
>> 26 * because this lets us support a wide range of HZ and
>> 27 * loops_per_jiffy values without either a or b overflowing 2^32.
>> 28 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
>> 29 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
>> 30 * (which corresponds to ~3800 bogomips at HZ = 100).
>> 31 * -- paulus
17 */ 32 */
>> 33 #define __MAX_UDELAY (226050910/HZ) /* maximum udelay argument */
>> 34 #define __MAX_NDELAY (2147483647/HZ) /* maximum ndelay argument */
18 35
19 /* 0x10c7 is 2**32 / 1000000 (rounded up) */ !! 36 extern __inline__ void __udelay(unsigned int x)
20 #define udelay(n) !! 37 {
21 ({ !! 38 unsigned int loops;
22 if (__builtin_constant_p(n)) { !! 39
23 if ((n) / 20000 >= 1) !! 40 __asm__("mulhwu %0,%1,%2" : "=r" (loops) :
24 __bad_udelay( !! 41 "r" (x), "r" (loops_per_jiffy * 226));
25 else !! 42 __delay(loops);
26 __const_udelay !! 43 }
27 } else { !! 44
28 __udelay(n); !! 45 extern __inline__ void __ndelay(unsigned int x)
29 } !! 46 {
30 }) !! 47 unsigned int loops;
31 !! 48
32 /* 0x5 is 2**32 / 1000000000 (rounded up) */ !! 49 __asm__("mulhwu %0,%1,%2" : "=r" (loops) :
33 #define ndelay(n) !! 50 "r" (x), "r" (loops_per_jiffy * 5));
34 ({ !! 51 __delay(loops);
35 if (__builtin_constant_p(n)) { !! 52 }
36 if ((n) / 20000 >= 1) !! 53
37 __bad_ndelay() !! 54 extern void __bad_udelay(void); /* deliberately undefined */
38 else !! 55 extern void __bad_ndelay(void); /* deliberately undefined */
39 __const_udelay !! 56
40 } else { !! 57 #define udelay(n) (__builtin_constant_p(n)? \
41 __ndelay(n); !! 58 ((n) > __MAX_UDELAY? __bad_udelay(): __udelay((n) * (19 * HZ))) : \
42 } !! 59 __udelay((n) * (19 * HZ)))
43 }) !! 60
>> 61 #define ndelay(n) (__builtin_constant_p(n)? \
>> 62 ((n) > __MAX_NDELAY? __bad_ndelay(): __ndelay((n) * HZ)) : \
>> 63 __ndelay((n) * HZ))
44 64
45 #endif /* __ASM_GENERIC_DELAY_H */ !! 65 #endif /* defined(_PPC_DELAY_H) */
>> 66 #endif /* __KERNEL__ */
46 67
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