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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - arch/mips/kernel/time.c
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
6 * Common time service routines for MIPS machines.
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.
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>
26 #include <asm/cpu-features.h>
27 #include <asm/cpu-type.h>
28 #include <asm/div64.h>
34 DEFINE_SPINLOCK(rtc_lock
);
35 EXPORT_SYMBOL(rtc_lock
);
37 static int null_perf_irq(void)
42 int (*perf_irq
)(void) = null_perf_irq
;
44 EXPORT_SYMBOL(perf_irq
);
47 * time_init() - it does the following things.
49 * 1) plat_time_init() -
50 * a) (optional) set up RTC routines,
51 * b) (optional) calibrate and set the mips_hpt_frequency
52 * (only needed if you intended to use cpu counter as timer interrupt
54 * 2) calculate a couple of cached variables for later usage
57 unsigned int mips_hpt_frequency
;
58 EXPORT_SYMBOL_GPL(mips_hpt_frequency
);
60 static __init
int cpu_has_mfc0_count_bug(void)
62 switch (current_cpu_type()) {
67 * V3.0 is documented as suffering from the mfc0 from count bug.
68 * Afaik this is the last version of the R4000. Later versions
69 * were marketed as R4400.
77 * The published errata for the R4400 up to 3.0 say the CPU
78 * has the mfc0 from count bug.
80 if ((current_cpu_data
.processor_id
& 0xff) <= 0x30)
84 * we assume newer revisions are ok
92 void __init
time_init(void)
97 * The use of the R4k timer as a clock event takes precedence;
98 * if reading the Count register might interfere with the timer
99 * interrupt, then we don't use the timer as a clock source.
100 * We may still use the timer as a clock source though if the
101 * timer interrupt isn't reliable; the interference doesn't
102 * matter then, because we don't use the interrupt.
104 if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug())
105 init_mips_clocksource();