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/processor.h>
16 #include <asm/param.h>
17 
18 extern unsigned long loops_per_jiffy;
19 
__delay(unsigned long loops)20 static inline void __delay(unsigned long loops)
21 {
22   /* 2 cycles per loop. */
23   __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
24 			: "=r" (loops) : "0" (loops));
25 }
26 
xtensa_get_ccount(void)27 static __inline__ u32 xtensa_get_ccount(void)
28 {
29 	u32 ccount;
30 	asm volatile ("rsr %0, 234; # CCOUNT\n" : "=r" (ccount));
31 	return ccount;
32 }
33 
34 /* For SMP/NUMA systems, change boot_cpu_data to something like
35  * local_cpu_data->... where local_cpu_data points to the current
36  * cpu. */
37 
udelay(unsigned long usecs)38 static __inline__ void udelay (unsigned long usecs)
39 {
40 	unsigned long start = xtensa_get_ccount();
41 	unsigned long cycles = usecs * (loops_per_jiffy / (1000000UL / HZ));
42 
43 	/* Note: all variables are unsigned (can wrap around)! */
44 	while (((unsigned long)xtensa_get_ccount()) - start < cycles)
45 		;
46 }
47 
48 #endif
49 
50