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>
21 #include <asm/div64.h>
22 #include <asm/processor.h>
23 #include <asm/intctl-regs.h>
26 #ifdef CONFIG_MN10300_RTC
27 unsigned long mn10300_ioclk; /* system I/O clock frequency */
28 unsigned long mn10300_iobclk; /* system I/O clock frequency */
29 unsigned long mn10300_tsc_per_HZ; /* number of ioclks per jiffy */
30 #endif /* CONFIG_MN10300_RTC */
32 static unsigned long mn10300_last_tsc; /* time-stamp counter at last time
33 * interrupt occurred */
35 static irqreturn_t timer_interrupt(int irq, void *dev_id);
37 static struct irqaction timer_irq = {
38 .handler = timer_interrupt,
39 .flags = IRQF_DISABLED | IRQF_SHARED | IRQF_TIMER,
43 static unsigned long sched_clock_multiplier;
46 * scheduler clock - returns current time in nanosec units.
48 unsigned long long sched_clock(void)
51 unsigned long long ll;
54 unsigned long tsc, tmp;
55 unsigned product[3]; /* 96-bit intermediate value */
59 tsc = 0 - get_cycles(); /* get_cycles() counts down */
62 * - sched_clock() must be called once a minute or better or the
63 * following will go horribly wrong - see cnt32_to_63()
65 tsc64.ll = cnt32_to_63(tsc) & 0x7fffffffffffffffULL;
67 /* scale the 64-bit TSC value to a nanosecond value via a 96-bit
70 asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */
71 "mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */
73 "addc 0,%2 \n" /* result in %2:%1:%0 */
74 : "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp)
75 : "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier)
78 result.l[0] = product[1] << 16 | product[0] >> 16;
79 result.l[1] = product[2] << 16 | product[1] >> 16;
85 * initialise the scheduler clock
87 static void __init mn10300_sched_clock_init(void)
89 sched_clock_multiplier =
90 __muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK);
94 * advance the kernel's time keeping clocks (xtime and jiffies)
95 * - we use Timer 0 & 1 cascaded as a clock to nudge us the next time
96 * there's a need to update
98 static irqreturn_t timer_interrupt(int irq, void *dev_id)
100 unsigned tsc, elapse;
102 write_seqlock(&xtime_lock);
104 while (tsc = get_cycles(),
105 elapse = mn10300_last_tsc - tsc, /* time elapsed since last
107 elapse > MN10300_TSC_PER_HZ
109 mn10300_last_tsc -= MN10300_TSC_PER_HZ;
111 /* advance the kernel's time tracking system */
112 profile_tick(CPU_PROFILING);
117 write_sequnlock(&xtime_lock);
119 update_process_times(user_mode(get_irq_regs()));
125 * initialise the various timers used by the main part of the kernel
127 void __init time_init(void)
129 /* we need the prescalar running to be able to use IOCLK/8
130 * - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock
131 * - IOCLK runs at Fosc rate (crystal speed)
133 TMPSCNT |= TMPSCNT_ENABLE;
135 startup_timestamp_counter();
138 "timestamp counter I/O clock running at %lu.%02lu"
139 " (calibrated against RTC)\n",
140 MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100);
142 xtime.tv_sec = get_initial_rtc_time();
145 mn10300_last_tsc = TMTSCBC;
147 /* use timer 0 & 1 cascaded to tick at as close to HZ as possible */
148 setup_irq(TMJCIRQ, &timer_irq);
150 set_intr_level(TMJCIRQ, TMJCICR_LEVEL);
152 startup_jiffies_counter();
154 #ifdef CONFIG_MN10300_WD_TIMER
155 /* start the watchdog timer */
159 mn10300_sched_clock_init();