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. See
7 * Documentation/mips/time.README.
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
14 #include <linux/bug.h>
15 #include <linux/clockchips.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/init.h>
19 #include <linux/sched.h>
20 #include <linux/param.h>
21 #include <linux/profile.h>
22 #include <linux/time.h>
23 #include <linux/timex.h>
24 #include <linux/smp.h>
25 #include <linux/kernel_stat.h>
26 #include <linux/spinlock.h>
27 #include <linux/interrupt.h>
28 #include <linux/module.h>
29 #include <linux/kallsyms.h>
31 #include <asm/bootinfo.h>
32 #include <asm/cache.h>
33 #include <asm/compiler.h>
35 #include <asm/cpu-features.h>
36 #include <asm/div64.h>
37 #include <asm/sections.h>
38 #include <asm/smtc_ipi.h>
46 DEFINE_SPINLOCK(rtc_lock);
47 EXPORT_SYMBOL(rtc_lock);
49 int __weak rtc_mips_set_time(unsigned long sec)
53 EXPORT_SYMBOL(rtc_mips_set_time);
55 int __weak rtc_mips_set_mmss(unsigned long nowtime)
57 return rtc_mips_set_time(nowtime);
60 int update_persistent_clock(struct timespec now)
62 return rtc_mips_set_mmss(now.tv_sec);
66 * Null high precision timer functions for systems lacking one.
68 static cycle_t null_hpt_read(void)
74 * High precision timer functions for a R4k-compatible timer.
76 static cycle_t c0_hpt_read(void)
78 return read_c0_count();
81 int (*mips_timer_state)(void);
83 int null_perf_irq(void)
88 EXPORT_SYMBOL(null_perf_irq);
90 int (*perf_irq)(void) = null_perf_irq;
92 EXPORT_SYMBOL(perf_irq);
95 * time_init() - it does the following things.
97 * 1) plat_time_init() -
98 * a) (optional) set up RTC routines,
99 * b) (optional) calibrate and set the mips_hpt_frequency
100 * (only needed if you intended to use cpu counter as timer interrupt
102 * 2) calculate a couple of cached variables for later usage
105 unsigned int mips_hpt_frequency;
107 static unsigned int __init calibrate_hpt(void)
109 cycle_t frequency, hpt_start, hpt_end, hpt_count, hz;
111 const int loops = HZ / 10;
116 * We want to calibrate for 0.1s, but to avoid a 64-bit
117 * division we round the number of loops up to the nearest
120 while (loops > 1 << log_2_loops)
122 i = 1 << log_2_loops;
125 * Wait for a rising edge of the timer interrupt.
127 while (mips_timer_state());
128 while (!mips_timer_state());
131 * Now see how many high precision timer ticks happen
132 * during the calculated number of periods between timer
135 hpt_start = clocksource_mips.read();
137 while (mips_timer_state());
138 while (!mips_timer_state());
140 hpt_end = clocksource_mips.read();
142 hpt_count = (hpt_end - hpt_start) & clocksource_mips.mask;
144 frequency = hpt_count * hz;
146 return frequency >> log_2_loops;
149 struct clocksource clocksource_mips = {
151 .mask = CLOCKSOURCE_MASK(32),
152 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
155 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
160 /* Find a shift value */
161 for (shift = 32; shift > 0; shift--) {
162 temp = (u64) NSEC_PER_SEC << shift;
164 if ((temp >> 32) == 0)
168 cs->mult = (u32) temp;
171 void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
177 /* Find a shift value */
178 for (shift = 32; shift > 0; shift--) {
179 temp = (u64) clock << shift;
180 do_div(temp, NSEC_PER_SEC);
181 if ((temp >> 32) == 0)
185 cd->mult = (u32) temp;
188 static void __init init_mips_clocksource(void)
190 if (!mips_hpt_frequency || clocksource_mips.read == null_hpt_read)
193 /* Calclate a somewhat reasonable rating value */
194 clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
196 clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
198 clocksource_register(&clocksource_mips);
201 void __init __weak plat_time_init(void)
206 * This function exists in order to cause an error due to a duplicate
207 * definition if platform code should have its own implementation. The hook
208 * to use instead is plat_time_init. plat_time_init does not receive the
209 * irqaction pointer argument anymore. This is because any function which
210 * initializes an interrupt timer now takes care of its own request_irq rsp.
211 * setup_irq calls and each clock_event_device should use its own
214 void __init plat_timer_setup(struct irqaction *irq)
219 void __init time_init(void)
223 /* Choose appropriate high precision timer routines. */
224 if (!cpu_has_counter && !clocksource_mips.read)
225 /* No high precision timer -- sorry. */
226 clocksource_mips.read = null_hpt_read;
227 else if (!mips_hpt_frequency && !mips_timer_state) {
228 /* A high precision timer of unknown frequency. */
229 if (!clocksource_mips.read)
230 /* No external high precision timer -- use R4k. */
231 clocksource_mips.read = c0_hpt_read;
233 /* We know counter frequency. Or we can get it. */
234 if (!clocksource_mips.read) {
235 /* No external high precision timer -- use R4k. */
236 clocksource_mips.read = c0_hpt_read;
238 if (!mips_hpt_frequency)
239 mips_hpt_frequency = calibrate_hpt();
241 /* Report the high precision timer rate for a reference. */
242 printk("Using %u.%03u MHz high precision timer.\n",
243 ((mips_hpt_frequency + 500) / 1000) / 1000,
244 ((mips_hpt_frequency + 500) / 1000) % 1000);
247 init_mips_clocksource();
248 mips_clockevent_init();