1 /* MN10300 Low level time management
3 * Copyright (C) 2007-2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 * - Derived from arch/i386/kernel/time.c
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public Licence
9 * as published by the Free Software Foundation; either version
10 * 2 of the Licence, or (at your option) any later version.
12 #include <linux/sched.h>
13 #include <linux/kernel.h>
14 #include <linux/interrupt.h>
15 #include <linux/time.h>
16 #include <linux/init.h>
17 #include <linux/smp.h>
18 #include <linux/profile.h>
19 #include <linux/cnt32_to_63.h>
20 #include <linux/clocksource.h>
21 #include <linux/clockchips.h>
23 #include <asm/div64.h>
24 #include <asm/processor.h>
25 #include <asm/intctl-regs.h>
29 static unsigned long mn10300_last_tsc; /* time-stamp counter at last time
30 * interrupt occurred */
32 static unsigned long sched_clock_multiplier;
35 * scheduler clock - returns current time in nanosec units.
37 unsigned long long sched_clock(void)
40 unsigned long long ll;
43 unsigned long tsc, tmp;
44 unsigned product[3]; /* 96-bit intermediate value */
46 /* cnt32_to_63() is not safe with preemption */
54 * - sched_clock() must be called once a minute or better or the
55 * following will go horribly wrong - see cnt32_to_63()
57 tsc64.ll = cnt32_to_63(tsc) & 0x7fffffffffffffffULL;
61 /* scale the 64-bit TSC value to a nanosecond value via a 96-bit
64 asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */
65 "mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */
67 "addc 0,%2 \n" /* result in %2:%1:%0 */
68 : "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp)
69 : "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier)
72 result.l[0] = product[1] << 16 | product[0] >> 16;
73 result.l[1] = product[2] << 16 | product[1] >> 16;
79 * initialise the scheduler clock
81 static void __init mn10300_sched_clock_init(void)
83 sched_clock_multiplier =
84 __muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK);
88 * local_timer_interrupt - Local timer interrupt handler
90 * Handle local timer interrupts for this CPU. They may have been propagated
91 * to this CPU from the CPU that actually gets them by way of an IPI.
93 irqreturn_t local_timer_interrupt(void)
95 profile_tick(CPU_PROFILING);
96 update_process_times(user_mode(get_irq_regs()));
100 #ifndef CONFIG_GENERIC_TIME
102 * advance the kernel's time keeping clocks (xtime and jiffies)
103 * - we use Timer 0 & 1 cascaded as a clock to nudge us the next time
104 * there's a need to update
106 static irqreturn_t timer_interrupt(int irq, void *dev_id)
108 unsigned tsc, elapse;
111 write_seqlock(&xtime_lock);
113 while (tsc = get_cycles(),
114 elapse = tsc - mn10300_last_tsc, /* time elapsed since last
116 elapse > MN10300_TSC_PER_HZ
118 mn10300_last_tsc += MN10300_TSC_PER_HZ;
120 /* advance the kernel's time tracking system */
124 write_sequnlock(&xtime_lock);
126 ret = local_timer_interrupt();
128 send_IPI_allbutself(LOCAL_TIMER_IPI);
133 static struct irqaction timer_irq = {
134 .handler = timer_interrupt,
135 .flags = IRQF_DISABLED | IRQF_SHARED | IRQF_TIMER,
138 #endif /* CONFIG_GENERIC_TIME */
140 #ifdef CONFIG_CSRC_MN10300
141 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
146 /* Find a shift value */
147 for (shift = 32; shift > 0; shift--) {
148 temp = (u64) NSEC_PER_SEC << shift;
150 if ((temp >> 32) == 0)
154 cs->mult = (u32) temp;
158 #if CONFIG_CEVT_MN10300
159 void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
165 /* Find a shift value */
166 for (shift = 32; shift > 0; shift--) {
167 temp = (u64) clock << shift;
168 do_div(temp, NSEC_PER_SEC);
169 if ((temp >> 32) == 0)
173 cd->mult = (u32) temp;
178 * initialise the various timers used by the main part of the kernel
180 void __init time_init(void)
182 /* we need the prescalar running to be able to use IOCLK/8
183 * - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock
184 * - IOCLK runs at Fosc rate (crystal speed)
186 TMPSCNT |= TMPSCNT_ENABLE;
188 #ifdef CONFIG_GENERIC_TIME
191 startup_timestamp_counter();
195 "timestamp counter I/O clock running at %lu.%02lu"
196 " (calibrated against RTC)\n",
197 MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100);
199 mn10300_last_tsc = read_timestamp_counter();
201 #ifdef CONFIG_GENERIC_CLOCKEVENTS
204 reload_jiffies_counter(MN10300_JC_PER_HZ - 1);
205 setup_jiffies_interrupt(TMJCIRQ, &timer_irq, CONFIG_TIMER_IRQ_LEVEL);
208 #ifdef CONFIG_MN10300_WD_TIMER
209 /* start the watchdog timer */
213 mn10300_sched_clock_init();