1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Precise Delay Loops for SuperH
4 *
5 * Copyright (C) 1999 Niibe Yutaka & Kaz Kojima
6 */
7
8 #include <linux/sched.h>
9 #include <linux/delay.h>
10
11 void __delay(unsigned long loops)
12 {
13 __asm__ __volatile__(
14 /*
15 * ST40-300 appears to have an issue with this code,
16 * normally taking two cycles each loop, as with all
17 * other SH variants. If however the branch and the
18 * delay slot straddle an 8 byte boundary, this increases
19 * to 3 cycles.
20 * This align directive ensures this doesn't occur.
21 */
22 ".balign 8\n\t"
23
24 "tst %0, %0\n\t"
25 "1:\t"
26 "bf/s 1b\n\t"
27 " dt %0"
28 : "=r" (loops)
29 : "" (loops)
30 : "t");
31 }
32
33 inline void __const_udelay(unsigned long xloops)
34 {
35 xloops *= 4;
36 __asm__("dmulu.l %0, %2\n\t"
37 "sts mach, %0"
38 : "=r" (xloops)
39 : "" (xloops),
40 "r" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4))
41 : "macl", "mach");
42 __delay(++xloops);
43 }
44
45 void __udelay(unsigned long usecs)
46 {
47 __const_udelay(usecs * 0x000010c6); /* 2**32 / 1000000 */
48 }
49
50 void __ndelay(unsigned long nsecs)
51 {
52 __const_udelay(nsecs * 0x00000005);
53 }
54
55
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.