summaryrefslogtreecommitdiffstats
path: root/arch/mips/kernel/time.c
blob: c036157fb891ff7e9a76c461b5ed0873c56743b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
/*
 * Copyright 2001 MontaVista Software Inc.
 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
 * Copyright (c) 2003, 2004  Maciej W. Rozycki
 *
 * Common time service routines for MIPS machines.
 *
 * This program is free software; you can redistribute	it and/or modify it
 * under  the terms of	the GNU General	 Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */
#include <linux/bug.h>
#include <linux/clockchips.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/export.h>

#include <asm/cpu-features.h>
#include <asm/cpu-type.h>
#include <asm/div64.h>
#include <asm/time.h>

/*
 * forward reference
 */
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);

int __weak rtc_mips_set_time(unsigned long sec)
{
	return -ENODEV;
}

int __weak rtc_mips_set_mmss(unsigned long nowtime)
{
	return rtc_mips_set_time(nowtime);
}

int update_persistent_clock(struct timespec now)
{
	return rtc_mips_set_mmss(now.tv_sec);
}

static int null_perf_irq(void)
{
	return 0;
}

int (*perf_irq)(void) = null_perf_irq;

EXPORT_SYMBOL(perf_irq);

/*
 * time_init() - it does the following things.
 *
 * 1) plat_time_init() -
 *	a) (optional) set up RTC routines,
 *	b) (optional) calibrate and set the mips_hpt_frequency
 *	    (only needed if you intended to use cpu counter as timer interrupt
 *	     source)
 * 2) calculate a couple of cached variables for later usage
 */

unsigned int mips_hpt_frequency;
EXPORT_SYMBOL_GPL(mips_hpt_frequency);

/*
 * This function exists in order to cause an error due to a duplicate
 * definition if platform code should have its own implementation.  The hook
 * to use instead is plat_time_init.  plat_time_init does not receive the
 * irqaction pointer argument anymore.	This is because any function which
 * initializes an interrupt timer now takes care of its own request_irq rsp.
 * setup_irq calls and each clock_event_device should use its own
 * struct irqrequest.
 */
void __init plat_timer_setup(void)
{
	BUG();
}

static __init int cpu_has_mfc0_count_bug(void)
{
	switch (current_cpu_type()) {
	case CPU_R4000PC:
	case CPU_R4000SC:
	case CPU_R4000MC:
		/*
		 * V3.0 is documented as suffering from the mfc0 from count bug.
		 * Afaik this is the last version of the R4000.	 Later versions
		 * were marketed as R4400.
		 */
		return 1;

	case CPU_R4400PC:
	case CPU_R4400SC:
	case CPU_R4400MC:
		/*
		 * The published errata for the R4400 up to 3.0 say the CPU
		 * has the mfc0 from count bug.
		 */
		if ((current_cpu_data.processor_id & 0xff) <= 0x30)
			return 1;

		/*
		 * we assume newer revisions are ok
		 */
		return 0;
	}

	return 0;
}

void __init time_init(void)
{
	plat_time_init();

	/*
	 * The use of the R4k timer as a clock event takes precedence;
	 * if reading the Count register might interfere with the timer
	 * interrupt, then we don't use the timer as a clock source.
	 * We may still use the timer as a clock source though if the
	 * timer interrupt isn't reliable; the interference doesn't
	 * matter then, because we don't use the interrupt.
	 */
	if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug())
		init_mips_clocksource();
}