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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/include/asm-arm/arch-ebsa110/system.h
3 *
4 * Copyright (C) 1996-2000 Russell King.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10#ifndef __ASM_ARCH_SYSTEM_H
11#define __ASM_ARCH_SYSTEM_H
12
13/*
14 * EBSA110 idling methodology:
15 *
16 * We can not execute the "wait for interrupt" instruction since that
17 * will stop our MCLK signal (which provides the clock for the glue
18 * logic, and therefore the timer interrupt).
19 *
20 * Instead, we spin, polling the IRQ_STAT register for the occurrence
21 * of any interrupt with core clock down to the memory clock.
22 */
23static inline void arch_idle(void)
24{
25 const char *irq_stat = (char *)0xff000000;
26
27 /* disable clock switching */
28 asm volatile ("mcr p15, 0, ip, c15, c2, 2" : : : "cc");
29
30 /* wait for an interrupt to occur */
31 while (!*irq_stat);
32
33 /* enable clock switching */
34 asm volatile ("mcr p15, 0, ip, c15, c1, 2" : : : "cc");
35}
36
37#define arch_reset(mode) cpu_reset(0x80000000)
38
39#endif