1/*
2 * Copyright 2001 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 * Copyright (c) 2003, 2004  Maciej W. Rozycki
5 *
6 * Common time service routines for MIPS machines.
7 *
8 * This program is free software; you can redistribute	it and/or modify it
9 * under  the terms of	the GNU General	 Public License as published by the
10 * Free Software Foundation;  either version 2 of the  License, or (at your
11 * option) any later version.
12 */
13#include <linux/bug.h>
14#include <linux/clockchips.h>
15#include <linux/types.h>
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/sched.h>
19#include <linux/param.h>
20#include <linux/time.h>
21#include <linux/timex.h>
22#include <linux/smp.h>
23#include <linux/spinlock.h>
24#include <linux/export.h>
25
26#include <asm/cpu-features.h>
27#include <asm/cpu-type.h>
28#include <asm/div64.h>
29#include <asm/time.h>
30
31/*
32 * forward reference
33 */
34DEFINE_SPINLOCK(rtc_lock);
35EXPORT_SYMBOL(rtc_lock);
36
37int __weak rtc_mips_set_time(unsigned long sec)
38{
39	return 0;
40}
41
42int __weak rtc_mips_set_mmss(unsigned long nowtime)
43{
44	return rtc_mips_set_time(nowtime);
45}
46
47int update_persistent_clock(struct timespec now)
48{
49	return rtc_mips_set_mmss(now.tv_sec);
50}
51
52static int null_perf_irq(void)
53{
54	return 0;
55}
56
57int (*perf_irq)(void) = null_perf_irq;
58
59EXPORT_SYMBOL(perf_irq);
60
61/*
62 * time_init() - it does the following things.
63 *
64 * 1) plat_time_init() -
65 *	a) (optional) set up RTC routines,
66 *	b) (optional) calibrate and set the mips_hpt_frequency
67 *	    (only needed if you intended to use cpu counter as timer interrupt
68 *	     source)
69 * 2) calculate a couple of cached variables for later usage
70 */
71
72unsigned int mips_hpt_frequency;
73
74/*
75 * This function exists in order to cause an error due to a duplicate
76 * definition if platform code should have its own implementation.  The hook
77 * to use instead is plat_time_init.  plat_time_init does not receive the
78 * irqaction pointer argument anymore.	This is because any function which
79 * initializes an interrupt timer now takes care of its own request_irq rsp.
80 * setup_irq calls and each clock_event_device should use its own
81 * struct irqrequest.
82 */
83void __init plat_timer_setup(void)
84{
85	BUG();
86}
87
88static __init int cpu_has_mfc0_count_bug(void)
89{
90	switch (current_cpu_type()) {
91	case CPU_R4000PC:
92	case CPU_R4000SC:
93	case CPU_R4000MC:
94		/*
95		 * V3.0 is documented as suffering from the mfc0 from count bug.
96		 * Afaik this is the last version of the R4000.	 Later versions
97		 * were marketed as R4400.
98		 */
99		return 1;
100
101	case CPU_R4400PC:
102	case CPU_R4400SC:
103	case CPU_R4400MC:
104		/*
105		 * The published errata for the R4400 up to 3.0 say the CPU
106		 * has the mfc0 from count bug.
107		 */
108		if ((current_cpu_data.processor_id & 0xff) <= 0x30)
109			return 1;
110
111		/*
112		 * we assume newer revisions are ok
113		 */
114		return 0;
115	}
116
117	return 0;
118}
119
120void __init time_init(void)
121{
122	plat_time_init();
123
124	/*
125	 * The use of the R4k timer as a clock event takes precedence;
126	 * if reading the Count register might interfere with the timer
127	 * interrupt, then we don't use the timer as a clock source.
128	 * We may still use the timer as a clock source though if the
129	 * timer interrupt isn't reliable; the interference doesn't
130	 * matter then, because we don't use the interrupt.
131	 */
132	if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug())
133		init_mips_clocksource();
134}
135