| 1 | /* MN10300 Low level time management |
| 2 | * |
| 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 |
| 6 | * |
| 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. |
| 11 | */ |
| 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> |
| 22 | #include <asm/irq.h> |
| 23 | #include <asm/div64.h> |
| 24 | #include <asm/processor.h> |
| 25 | #include <asm/intctl-regs.h> |
| 26 | #include <asm/rtc.h> |
| 27 | #include "internal.h" |
| 28 | |
| 29 | static unsigned long mn10300_last_tsc; /* time-stamp counter at last time |
| 30 | * interrupt occurred */ |
| 31 | |
| 32 | static unsigned long sched_clock_multiplier; |
| 33 | |
| 34 | /* |
| 35 | * scheduler clock - returns current time in nanosec units. |
| 36 | */ |
| 37 | unsigned long long sched_clock(void) |
| 38 | { |
| 39 | union { |
| 40 | unsigned long long ll; |
| 41 | unsigned l[2]; |
| 42 | } tsc64, result; |
| 43 | unsigned long tmp; |
| 44 | unsigned product[3]; /* 96-bit intermediate value */ |
| 45 | |
| 46 | /* cnt32_to_63() is not safe with preemption */ |
| 47 | preempt_disable(); |
| 48 | |
| 49 | /* expand the tsc to 64-bits. |
| 50 | * - sched_clock() must be called once a minute or better or the |
| 51 | * following will go horribly wrong - see cnt32_to_63() |
| 52 | */ |
| 53 | tsc64.ll = cnt32_to_63(get_cycles()) & 0x7fffffffffffffffULL; |
| 54 | |
| 55 | preempt_enable(); |
| 56 | |
| 57 | /* scale the 64-bit TSC value to a nanosecond value via a 96-bit |
| 58 | * intermediate |
| 59 | */ |
| 60 | asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */ |
| 61 | "mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */ |
| 62 | "add %3,%1 \n" |
| 63 | "addc 0,%2 \n" /* result in %2:%1:%0 */ |
| 64 | : "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp) |
| 65 | : "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier) |
| 66 | : "cc"); |
| 67 | |
| 68 | result.l[0] = product[1] << 16 | product[0] >> 16; |
| 69 | result.l[1] = product[2] << 16 | product[1] >> 16; |
| 70 | |
| 71 | return result.ll; |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * initialise the scheduler clock |
| 76 | */ |
| 77 | static void __init mn10300_sched_clock_init(void) |
| 78 | { |
| 79 | sched_clock_multiplier = |
| 80 | __muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK); |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * local_timer_interrupt - Local timer interrupt handler |
| 85 | * |
| 86 | * Handle local timer interrupts for this CPU. They may have been propagated |
| 87 | * to this CPU from the CPU that actually gets them by way of an IPI. |
| 88 | */ |
| 89 | irqreturn_t local_timer_interrupt(void) |
| 90 | { |
| 91 | profile_tick(CPU_PROFILING); |
| 92 | update_process_times(user_mode(get_irq_regs())); |
| 93 | return IRQ_HANDLED; |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | * initialise the various timers used by the main part of the kernel |
| 98 | */ |
| 99 | void __init time_init(void) |
| 100 | { |
| 101 | /* we need the prescalar running to be able to use IOCLK/8 |
| 102 | * - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock |
| 103 | * - IOCLK runs at Fosc rate (crystal speed) |
| 104 | */ |
| 105 | TMPSCNT |= TMPSCNT_ENABLE; |
| 106 | |
| 107 | init_clocksource(); |
| 108 | |
| 109 | printk(KERN_INFO |
| 110 | "timestamp counter I/O clock running at %lu.%02lu" |
| 111 | " (calibrated against RTC)\n", |
| 112 | MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100); |
| 113 | |
| 114 | mn10300_last_tsc = read_timestamp_counter(); |
| 115 | |
| 116 | init_clockevents(); |
| 117 | |
| 118 | #ifdef CONFIG_MN10300_WD_TIMER |
| 119 | /* start the watchdog timer */ |
| 120 | watchdog_go(); |
| 121 | #endif |
| 122 | |
| 123 | mn10300_sched_clock_init(); |
| 124 | } |