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/module.h>
26 #include <asm/cpu-features.h>
27 #include <asm/div64.h>
28 #include <asm/smtc_ipi.h>
34 DEFINE_SPINLOCK(rtc_lock
);
35 EXPORT_SYMBOL(rtc_lock
);
37 int __weak
rtc_mips_set_time(unsigned long sec
)
41 EXPORT_SYMBOL(rtc_mips_set_time
);
43 int __weak
rtc_mips_set_mmss(unsigned long nowtime
)
45 return rtc_mips_set_time(nowtime
);
48 int update_persistent_clock(struct timespec now
)
50 return rtc_mips_set_mmss(now
.tv_sec
);
54 * High precision timer functions for a R4k-compatible timer.
56 static cycle_t
c0_hpt_read(void)
58 return read_c0_count();
61 int (*mips_timer_state
)(void);
63 int null_perf_irq(void)
68 EXPORT_SYMBOL(null_perf_irq
);
70 int (*perf_irq
)(void) = null_perf_irq
;
72 EXPORT_SYMBOL(perf_irq
);
75 * time_init() - it does the following things.
77 * 1) plat_time_init() -
78 * a) (optional) set up RTC routines,
79 * b) (optional) calibrate and set the mips_hpt_frequency
80 * (only needed if you intended to use cpu counter as timer interrupt
82 * 2) calculate a couple of cached variables for later usage
85 unsigned int mips_hpt_frequency
;
87 static struct clocksource clocksource_mips
= {
90 .mask
= CLOCKSOURCE_MASK(32),
91 .flags
= CLOCK_SOURCE_IS_CONTINUOUS
,
94 void __init
clocksource_set_clock(struct clocksource
*cs
, unsigned int clock
)
99 /* Find a shift value */
100 for (shift
= 32; shift
> 0; shift
--) {
101 temp
= (u64
) NSEC_PER_SEC
<< shift
;
103 if ((temp
>> 32) == 0)
107 cs
->mult
= (u32
) temp
;
110 void __cpuinit
clockevent_set_clock(struct clock_event_device
*cd
,
116 /* Find a shift value */
117 for (shift
= 32; shift
> 0; shift
--) {
118 temp
= (u64
) clock
<< shift
;
119 do_div(temp
, NSEC_PER_SEC
);
120 if ((temp
>> 32) == 0)
124 cd
->mult
= (u32
) temp
;
127 static void __init
init_mips_clocksource(void)
129 /* Calclate a somewhat reasonable rating value */
130 clocksource_mips
.rating
= 200 + mips_hpt_frequency
/ 10000000;
132 clocksource_set_clock(&clocksource_mips
, mips_hpt_frequency
);
134 clocksource_register(&clocksource_mips
);
137 void __init __weak
plat_time_init(void)
142 * This function exists in order to cause an error due to a duplicate
143 * definition if platform code should have its own implementation. The hook
144 * to use instead is plat_time_init. plat_time_init does not receive the
145 * irqaction pointer argument anymore. This is because any function which
146 * initializes an interrupt timer now takes care of its own request_irq rsp.
147 * setup_irq calls and each clock_event_device should use its own
150 void __init
plat_timer_setup(void)
155 static __init
int cpu_has_mfc0_count_bug(void)
157 switch (current_cpu_type()) {
162 * V3.0 is documented as suffering from the mfc0 from count bug.
163 * Afaik this is the last version of the R4000. Later versions
164 * were marketed as R4400.
172 * The published errata for the R4400 upto 3.0 say the CPU
173 * has the mfc0 from count bug.
175 if ((current_cpu_data
.processor_id
& 0xff) <= 0x30)
179 * I don't have erratas for newer R4400 so be paranoid.
187 void __init
time_init(void)
191 if (mips_clockevent_init() || !cpu_has_mfc0_count_bug())
192 init_mips_clocksource();