From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- arch/alpha/kernel/time.c | 523 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 523 insertions(+) create mode 100644 arch/alpha/kernel/time.c (limited to 'arch/alpha/kernel/time.c') diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c new file mode 100644 index 00000000..f20d1b53 --- /dev/null +++ b/arch/alpha/kernel/time.c @@ -0,0 +1,523 @@ +/* + * linux/arch/alpha/kernel/time.c + * + * Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds + * + * This file contains the PC-specific time handling details: + * reading the RTC at bootup, etc.. + * 1994-07-02 Alan Modra + * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime + * 1995-03-26 Markus Kuhn + * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887 + * precision CMOS clock update + * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 + * "A Kernel Model for Precision Timekeeping" by Dave Mills + * 1997-01-09 Adrian Sun + * use interval timer if CONFIG_RTC=y + * 1997-10-29 John Bowman (bowman@math.ualberta.ca) + * fixed tick loss calculation in timer_interrupt + * (round system clock to nearest tick instead of truncating) + * fixed algorithm in time_init for getting time from CMOS clock + * 1999-04-16 Thorsten Kranzkowski (dl8bcu@gmx.net) + * fixed algorithm in do_gettimeofday() for calculating the precise time + * from processor cycle counter (now taking lost_ticks into account) + * 2000-08-13 Jan-Benedict Glaw + * Fixed time_init to be aware of epoches != 1900. This prevents + * booting up in 2048 for me;) Code is stolen from rtc.c. + * 2003-06-03 R. Scott Bailey + * Tighten sanity in time_init from 1% (10,000 PPM) to 250 PPM + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#include "proto.h" +#include "irq_impl.h" + +static int set_rtc_mmss(unsigned long); + +DEFINE_SPINLOCK(rtc_lock); +EXPORT_SYMBOL(rtc_lock); + +#define TICK_SIZE (tick_nsec / 1000) + +/* + * Shift amount by which scaled_ticks_per_cycle is scaled. Shifting + * by 48 gives us 16 bits for HZ while keeping the accuracy good even + * for large CPU clock rates. + */ +#define FIX_SHIFT 48 + +/* lump static variables together for more efficient access: */ +static struct { + /* cycle counter last time it got invoked */ + __u32 last_time; + /* ticks/cycle * 2^48 */ + unsigned long scaled_ticks_per_cycle; + /* partial unused tick */ + unsigned long partial_tick; +} state; + +unsigned long est_cycle_freq; + +#ifdef CONFIG_IRQ_WORK + +DEFINE_PER_CPU(u8, irq_work_pending); + +#define set_irq_work_pending_flag() __get_cpu_var(irq_work_pending) = 1 +#define test_irq_work_pending() __get_cpu_var(irq_work_pending) +#define clear_irq_work_pending() __get_cpu_var(irq_work_pending) = 0 + +void arch_irq_work_raise(void) +{ + set_irq_work_pending_flag(); +} + +#else /* CONFIG_IRQ_WORK */ + +#define test_irq_work_pending() 0 +#define clear_irq_work_pending() + +#endif /* CONFIG_IRQ_WORK */ + + +static inline __u32 rpcc(void) +{ + __u32 result; + asm volatile ("rpcc %0" : "=r"(result)); + return result; +} + +int update_persistent_clock(struct timespec now) +{ + return set_rtc_mmss(now.tv_sec); +} + +void read_persistent_clock(struct timespec *ts) +{ + unsigned int year, mon, day, hour, min, sec, epoch; + + sec = CMOS_READ(RTC_SECONDS); + min = CMOS_READ(RTC_MINUTES); + hour = CMOS_READ(RTC_HOURS); + day = CMOS_READ(RTC_DAY_OF_MONTH); + mon = CMOS_READ(RTC_MONTH); + year = CMOS_READ(RTC_YEAR); + + if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { + sec = bcd2bin(sec); + min = bcd2bin(min); + hour = bcd2bin(hour); + day = bcd2bin(day); + mon = bcd2bin(mon); + year = bcd2bin(year); + } + + /* PC-like is standard; used for year >= 70 */ + epoch = 1900; + if (year < 20) + epoch = 2000; + else if (year >= 20 && year < 48) + /* NT epoch */ + epoch = 1980; + else if (year >= 48 && year < 70) + /* Digital UNIX epoch */ + epoch = 1952; + + printk(KERN_INFO "Using epoch = %d\n", epoch); + + if ((year += epoch) < 1970) + year += 100; + + ts->tv_sec = mktime(year, mon, day, hour, min, sec); + ts->tv_nsec = 0; +} + + + +/* + * timer_interrupt() needs to keep up the real-time clock, + * as well as call the "xtime_update()" routine every clocktick + */ +irqreturn_t timer_interrupt(int irq, void *dev) +{ + unsigned long delta; + __u32 now; + long nticks; + +#ifndef CONFIG_SMP + /* Not SMP, do kernel PC profiling here. */ + profile_tick(CPU_PROFILING); +#endif + + /* + * Calculate how many ticks have passed since the last update, + * including any previous partial leftover. Save any resulting + * fraction for the next pass. + */ + now = rpcc(); + delta = now - state.last_time; + state.last_time = now; + delta = delta * state.scaled_ticks_per_cycle + state.partial_tick; + state.partial_tick = delta & ((1UL << FIX_SHIFT) - 1); + nticks = delta >> FIX_SHIFT; + + if (nticks) + xtime_update(nticks); + + if (test_irq_work_pending()) { + clear_irq_work_pending(); + irq_work_run(); + } + +#ifndef CONFIG_SMP + while (nticks--) + update_process_times(user_mode(get_irq_regs())); +#endif + + return IRQ_HANDLED; +} + +void __init +common_init_rtc(void) +{ + unsigned char x; + + /* Reset periodic interrupt frequency. */ + x = CMOS_READ(RTC_FREQ_SELECT) & 0x3f; + /* Test includes known working values on various platforms + where 0x26 is wrong; we refuse to change those. */ + if (x != 0x26 && x != 0x25 && x != 0x19 && x != 0x06) { + printk("Setting RTC_FREQ to 1024 Hz (%x)\n", x); + CMOS_WRITE(0x26, RTC_FREQ_SELECT); + } + + /* Turn on periodic interrupts. */ + x = CMOS_READ(RTC_CONTROL); + if (!(x & RTC_PIE)) { + printk("Turning on RTC interrupts.\n"); + x |= RTC_PIE; + x &= ~(RTC_AIE | RTC_UIE); + CMOS_WRITE(x, RTC_CONTROL); + } + (void) CMOS_READ(RTC_INTR_FLAGS); + + outb(0x36, 0x43); /* pit counter 0: system timer */ + outb(0x00, 0x40); + outb(0x00, 0x40); + + outb(0xb6, 0x43); /* pit counter 2: speaker */ + outb(0x31, 0x42); + outb(0x13, 0x42); + + init_rtc_irq(); +} + +unsigned int common_get_rtc_time(struct rtc_time *time) +{ + return __get_rtc_time(time); +} + +int common_set_rtc_time(struct rtc_time *time) +{ + return __set_rtc_time(time); +} + +/* Validate a computed cycle counter result against the known bounds for + the given processor core. There's too much brokenness in the way of + timing hardware for any one method to work everywhere. :-( + + Return 0 if the result cannot be trusted, otherwise return the argument. */ + +static unsigned long __init +validate_cc_value(unsigned long cc) +{ + static struct bounds { + unsigned int min, max; + } cpu_hz[] __initdata = { + [EV3_CPU] = { 50000000, 200000000 }, /* guess */ + [EV4_CPU] = { 100000000, 300000000 }, + [LCA4_CPU] = { 100000000, 300000000 }, /* guess */ + [EV45_CPU] = { 200000000, 300000000 }, + [EV5_CPU] = { 250000000, 433000000 }, + [EV56_CPU] = { 333000000, 667000000 }, + [PCA56_CPU] = { 400000000, 600000000 }, /* guess */ + [PCA57_CPU] = { 500000000, 600000000 }, /* guess */ + [EV6_CPU] = { 466000000, 600000000 }, + [EV67_CPU] = { 600000000, 750000000 }, + [EV68AL_CPU] = { 750000000, 940000000 }, + [EV68CB_CPU] = { 1000000000, 1333333333 }, + /* None of the following are shipping as of 2001-11-01. */ + [EV68CX_CPU] = { 1000000000, 1700000000 }, /* guess */ + [EV69_CPU] = { 1000000000, 1700000000 }, /* guess */ + [EV7_CPU] = { 800000000, 1400000000 }, /* guess */ + [EV79_CPU] = { 1000000000, 2000000000 }, /* guess */ + }; + + /* Allow for some drift in the crystal. 10MHz is more than enough. */ + const unsigned int deviation = 10000000; + + struct percpu_struct *cpu; + unsigned int index; + + cpu = (struct percpu_struct *)((char*)hwrpb + hwrpb->processor_offset); + index = cpu->type & 0xffffffff; + + /* If index out of bounds, no way to validate. */ + if (index >= ARRAY_SIZE(cpu_hz)) + return cc; + + /* If index contains no data, no way to validate. */ + if (cpu_hz[index].max == 0) + return cc; + + if (cc < cpu_hz[index].min - deviation + || cc > cpu_hz[index].max + deviation) + return 0; + + return cc; +} + + +/* + * Calibrate CPU clock using legacy 8254 timer/counter. Stolen from + * arch/i386/time.c. + */ + +#define CALIBRATE_LATCH 0xffff +#define TIMEOUT_COUNT 0x100000 + +static unsigned long __init +calibrate_cc_with_pit(void) +{ + int cc, count = 0; + + /* Set the Gate high, disable speaker */ + outb((inb(0x61) & ~0x02) | 0x01, 0x61); + + /* + * Now let's take care of CTC channel 2 + * + * Set the Gate high, program CTC channel 2 for mode 0, + * (interrupt on terminal count mode), binary count, + * load 5 * LATCH count, (LSB and MSB) to begin countdown. + */ + outb(0xb0, 0x43); /* binary, mode 0, LSB/MSB, Ch 2 */ + outb(CALIBRATE_LATCH & 0xff, 0x42); /* LSB of count */ + outb(CALIBRATE_LATCH >> 8, 0x42); /* MSB of count */ + + cc = rpcc(); + do { + count++; + } while ((inb(0x61) & 0x20) == 0 && count < TIMEOUT_COUNT); + cc = rpcc() - cc; + + /* Error: ECTCNEVERSET or ECPUTOOFAST. */ + if (count <= 1 || count == TIMEOUT_COUNT) + return 0; + + return ((long)cc * PIT_TICK_RATE) / (CALIBRATE_LATCH + 1); +} + +/* The Linux interpretation of the CMOS clock register contents: + When the Update-In-Progress (UIP) flag goes from 1 to 0, the + RTC registers show the second which has precisely just started. + Let's hope other operating systems interpret the RTC the same way. */ + +static unsigned long __init +rpcc_after_update_in_progress(void) +{ + do { } while (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)); + do { } while (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP); + + return rpcc(); +} + +#ifndef CONFIG_SMP +/* Until and unless we figure out how to get cpu cycle counters + in sync and keep them there, we can't use the rpcc. */ +static cycle_t read_rpcc(struct clocksource *cs) +{ + cycle_t ret = (cycle_t)rpcc(); + return ret; +} + +static struct clocksource clocksource_rpcc = { + .name = "rpcc", + .rating = 300, + .read = read_rpcc, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS +}; + +static inline void register_rpcc_clocksource(long cycle_freq) +{ + clocksource_register_hz(&clocksource_rpcc, cycle_freq); +} +#else /* !CONFIG_SMP */ +static inline void register_rpcc_clocksource(long cycle_freq) +{ +} +#endif /* !CONFIG_SMP */ + +void __init +time_init(void) +{ + unsigned int cc1, cc2; + unsigned long cycle_freq, tolerance; + long diff; + + /* Calibrate CPU clock -- attempt #1. */ + if (!est_cycle_freq) + est_cycle_freq = validate_cc_value(calibrate_cc_with_pit()); + + cc1 = rpcc(); + + /* Calibrate CPU clock -- attempt #2. */ + if (!est_cycle_freq) { + cc1 = rpcc_after_update_in_progress(); + cc2 = rpcc_after_update_in_progress(); + est_cycle_freq = validate_cc_value(cc2 - cc1); + cc1 = cc2; + } + + cycle_freq = hwrpb->cycle_freq; + if (est_cycle_freq) { + /* If the given value is within 250 PPM of what we calculated, + accept it. Otherwise, use what we found. */ + tolerance = cycle_freq / 4000; + diff = cycle_freq - est_cycle_freq; + if (diff < 0) + diff = -diff; + if ((unsigned long)diff > tolerance) { + cycle_freq = est_cycle_freq; + printk("HWRPB cycle frequency bogus. " + "Estimated %lu Hz\n", cycle_freq); + } else { + est_cycle_freq = 0; + } + } else if (! validate_cc_value (cycle_freq)) { + printk("HWRPB cycle frequency bogus, " + "and unable to estimate a proper value!\n"); + } + + /* From John Bowman : allow the values + to settle, as the Update-In-Progress bit going low isn't good + enough on some hardware. 2ms is our guess; we haven't found + bogomips yet, but this is close on a 500Mhz box. */ + __delay(1000000); + + + if (HZ > (1<<16)) { + extern void __you_loose (void); + __you_loose(); + } + + register_rpcc_clocksource(cycle_freq); + + state.last_time = cc1; + state.scaled_ticks_per_cycle + = ((unsigned long) HZ << FIX_SHIFT) / cycle_freq; + state.partial_tick = 0L; + + /* Startup the timer source. */ + alpha_mv.init_rtc(); +} + +/* + * In order to set the CMOS clock precisely, set_rtc_mmss has to be + * called 500 ms after the second nowtime has started, because when + * nowtime is written into the registers of the CMOS clock, it will + * jump to the next second precisely 500 ms later. Check the Motorola + * MC146818A or Dallas DS12887 data sheet for details. + * + * BUG: This routine does not handle hour overflow properly; it just + * sets the minutes. Usually you won't notice until after reboot! + */ + + +static int +set_rtc_mmss(unsigned long nowtime) +{ + int retval = 0; + int real_seconds, real_minutes, cmos_minutes; + unsigned char save_control, save_freq_select; + + /* irq are locally disabled here */ + spin_lock(&rtc_lock); + /* Tell the clock it's being set */ + save_control = CMOS_READ(RTC_CONTROL); + CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); + + /* Stop and reset prescaler */ + save_freq_select = CMOS_READ(RTC_FREQ_SELECT); + CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); + + cmos_minutes = CMOS_READ(RTC_MINUTES); + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) + cmos_minutes = bcd2bin(cmos_minutes); + + /* + * since we're only adjusting minutes and seconds, + * don't interfere with hour overflow. This avoids + * messing with unknown time zones but requires your + * RTC not to be off by more than 15 minutes + */ + real_seconds = nowtime % 60; + real_minutes = nowtime / 60; + if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) { + /* correct for half hour time zone */ + real_minutes += 30; + } + real_minutes %= 60; + + if (abs(real_minutes - cmos_minutes) < 30) { + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { + real_seconds = bin2bcd(real_seconds); + real_minutes = bin2bcd(real_minutes); + } + CMOS_WRITE(real_seconds,RTC_SECONDS); + CMOS_WRITE(real_minutes,RTC_MINUTES); + } else { + printk_once(KERN_NOTICE + "set_rtc_mmss: can't update from %d to %d\n", + cmos_minutes, real_minutes); + retval = -1; + } + + /* The following flags have to be released exactly in this order, + * otherwise the DS12887 (popular MC146818A clone with integrated + * battery and quartz) will not reset the oscillator and will not + * update precisely 500 ms later. You won't find this mentioned in + * the Dallas Semiconductor data sheets, but who believes data + * sheets anyway ... -- Markus Kuhn + */ + CMOS_WRITE(save_control, RTC_CONTROL); + CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); + spin_unlock(&rtc_lock); + + return retval; +} -- cgit v1.2.3