From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- arch/alpha/kernel/time.c | 458 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 458 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 0000000000..4d01c392ab --- /dev/null +++ b/arch/alpha/kernel/time.c @@ -0,0 +1,458 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/arch/alpha/kernel/time.c + * + * Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds + * + * This file contains the clocksource time handling. + * 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) + * 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 "proto.h" +#include "irq_impl.h" + +DEFINE_SPINLOCK(rtc_lock); +EXPORT_SYMBOL(rtc_lock); + +unsigned long est_cycle_freq; + +#ifdef CONFIG_IRQ_WORK + +DEFINE_PER_CPU(u8, irq_work_pending); + +#define set_irq_work_pending_flag() __this_cpu_write(irq_work_pending, 1) +#define test_irq_work_pending() __this_cpu_read(irq_work_pending) +#define clear_irq_work_pending() __this_cpu_write(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) +{ + return __builtin_alpha_rpcc(); +} + + + +/* + * The RTC as a clock_event_device primitive. + */ + +static DEFINE_PER_CPU(struct clock_event_device, cpu_ce); + +irqreturn_t +rtc_timer_interrupt(int irq, void *dev) +{ + int cpu = smp_processor_id(); + struct clock_event_device *ce = &per_cpu(cpu_ce, cpu); + + /* Don't run the hook for UNUSED or SHUTDOWN. */ + if (likely(clockevent_state_periodic(ce))) + ce->event_handler(ce); + + if (test_irq_work_pending()) { + clear_irq_work_pending(); + irq_work_run(); + } + + return IRQ_HANDLED; +} + +static int +rtc_ce_set_next_event(unsigned long evt, struct clock_event_device *ce) +{ + /* This hook is for oneshot mode, which we don't support. */ + return -EINVAL; +} + +static void __init +init_rtc_clockevent(void) +{ + int cpu = smp_processor_id(); + struct clock_event_device *ce = &per_cpu(cpu_ce, cpu); + + *ce = (struct clock_event_device){ + .name = "rtc", + .features = CLOCK_EVT_FEAT_PERIODIC, + .rating = 100, + .cpumask = cpumask_of(cpu), + .set_next_event = rtc_ce_set_next_event, + }; + + clockevents_config_and_register(ce, CONFIG_HZ, 0, 0); +} + + +/* + * The QEMU clock as a clocksource primitive. + */ + +static u64 +qemu_cs_read(struct clocksource *cs) +{ + return qemu_get_vmtime(); +} + +static struct clocksource qemu_cs = { + .name = "qemu", + .rating = 400, + .read = qemu_cs_read, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .max_idle_ns = LONG_MAX +}; + + +/* + * The QEMU alarm as a clock_event_device primitive. + */ + +static int qemu_ce_shutdown(struct clock_event_device *ce) +{ + /* The mode member of CE is updated for us in generic code. + Just make sure that the event is disabled. */ + qemu_set_alarm_abs(0); + return 0; +} + +static int +qemu_ce_set_next_event(unsigned long evt, struct clock_event_device *ce) +{ + qemu_set_alarm_rel(evt); + return 0; +} + +static irqreturn_t +qemu_timer_interrupt(int irq, void *dev) +{ + int cpu = smp_processor_id(); + struct clock_event_device *ce = &per_cpu(cpu_ce, cpu); + + ce->event_handler(ce); + return IRQ_HANDLED; +} + +static void __init +init_qemu_clockevent(void) +{ + int cpu = smp_processor_id(); + struct clock_event_device *ce = &per_cpu(cpu_ce, cpu); + + *ce = (struct clock_event_device){ + .name = "qemu", + .features = CLOCK_EVT_FEAT_ONESHOT, + .rating = 400, + .cpumask = cpumask_of(cpu), + .set_state_shutdown = qemu_ce_shutdown, + .set_state_oneshot = qemu_ce_shutdown, + .tick_resume = qemu_ce_shutdown, + .set_next_event = qemu_ce_set_next_event, + }; + + clockevents_config_and_register(ce, NSEC_PER_SEC, 1000, LONG_MAX); +} + + +void __init +common_init_rtc(void) +{ + unsigned char x, sel = 0; + + /* Reset periodic interrupt frequency. */ +#if CONFIG_HZ == 1024 || CONFIG_HZ == 1200 + 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) { + sel = RTC_REF_CLCK_32KHZ + 6; + } +#elif CONFIG_HZ == 256 || CONFIG_HZ == 128 || CONFIG_HZ == 64 || CONFIG_HZ == 32 + sel = RTC_REF_CLCK_32KHZ + __builtin_ffs(32768 / CONFIG_HZ); +#else +# error "Unknown HZ from arch/alpha/Kconfig" +#endif + if (sel) { + printk(KERN_INFO "Setting RTC_FREQ to %d Hz (%x)\n", + CONFIG_HZ, sel); + CMOS_WRITE(sel, 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(NULL); +} + + +#ifndef CONFIG_ALPHA_WTINT +/* + * The RPCC as a clocksource primitive. + * + * While we have free-running timecounters running on all CPUs, and we make + * a half-hearted attempt in init_rtc_rpcc_info to sync the timecounter + * with the wall clock, that initialization isn't kept up-to-date across + * different time counters in SMP mode. Therefore we can only use this + * method when there's only one CPU enabled. + * + * When using the WTINT PALcall, the RPCC may shift to a lower frequency, + * or stop altogether, while waiting for the interrupt. Therefore we cannot + * use this method when WTINT is in use. + */ + +static u64 read_rpcc(struct clocksource *cs) +{ + return rpcc(); +} + +static struct clocksource clocksource_rpcc = { + .name = "rpcc", + .rating = 300, + .read = read_rpcc, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS +}; +#endif /* ALPHA_WTINT */ + + +/* 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(); +} + +void __init +time_init(void) +{ + unsigned int cc1, cc2; + unsigned long cycle_freq, tolerance; + long diff; + + if (alpha_using_qemu) { + clocksource_register_hz(&qemu_cs, NSEC_PER_SEC); + init_qemu_clockevent(); + init_rtc_irq(qemu_timer_interrupt); + return; + } + + /* 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"); + } + + /* See above for restrictions on using clocksource_rpcc. */ +#ifndef CONFIG_ALPHA_WTINT + if (hwrpb->nr_processors == 1) + clocksource_register_hz(&clocksource_rpcc, cycle_freq); +#endif + + /* Startup the timer source. */ + alpha_mv.init_rtc(); + init_rtc_clockevent(); +} + +/* Initialize the clock_event_device for secondary cpus. */ +#ifdef CONFIG_SMP +void __init +init_clockevent(void) +{ + if (alpha_using_qemu) + init_qemu_clockevent(); + else + init_rtc_clockevent(); +} +#endif -- cgit v1.2.3