1 /*
2 * include/asm-xtensa/delay.h
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2001 - 2005 Tensilica Inc.
9 *
10 */
11
12 #ifndef _XTENSA_DELAY_H
13 #define _XTENSA_DELAY_H
14
15 #include <asm/timex.h>
16 #include <asm/param.h>
17
18 extern unsigned long loops_per_jiffy;
19
20 static inline void __delay(unsigned long loops)
21 {
22 if (__builtin_constant_p(loops) && loops < 2)
23 __asm__ __volatile__ ("nop");
24 else if (loops >= 2)
25 /* 2 cycles per loop. */
26 __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
27 : "+r" (loops));
28 }
29
30 /* Undefined function to get compile-time error */
31 void __bad_udelay(void);
32 void __bad_ndelay(void);
33
34 #define __MAX_UDELAY 30000
35 #define __MAX_NDELAY 30000
36
37 static inline void __udelay(unsigned long usecs)
38 {
39 unsigned long start = get_ccount();
40 unsigned long cycles = (usecs * (ccount_freq >> 15)) >> 5;
41
42 /* Note: all variables are unsigned (can wrap around)! */
43 while (((unsigned long)get_ccount()) - start < cycles)
44 cpu_relax();
45 }
46
47 static inline void udelay(unsigned long usec)
48 {
49 if (__builtin_constant_p(usec) && usec >= __MAX_UDELAY)
50 __bad_udelay();
51 else
52 __udelay(usec);
53 }
54
55 static inline void __ndelay(unsigned long nsec)
56 {
57 /*
58 * Inner shift makes sure multiplication doesn't overflow
59 * for legitimate nsec values
60 */
61 unsigned long cycles = (nsec * (ccount_freq >> 15)) >> 15;
62 __delay(cycles);
63 }
64
65 #define ndelay(n) ndelay(n)
66
67 static inline void ndelay(unsigned long nsec)
68 {
69 if (__builtin_constant_p(nsec) && nsec >= __MAX_NDELAY)
70 __bad_ndelay();
71 else
72 __ndelay(nsec);
73 }
74
75 #endif
76
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