path: root/arch/s390/kernel/time.c

// SPDX-License-Identifier: GPL-2.0
/*
 *    Time of day based timer functions.
 *
 *  S390 version
 *    Copyright IBM Corp. 1999, 2008
 *    Author(s): Hartmut Penner (hp@de.ibm.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com),
 *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
 *
 *  Derived from "arch/i386/kernel/time.c"
 *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
 */

#define KMSG_COMPONENT "time"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kernel_stat.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <linux/stop_machine.h>
#include <linux/time.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/types.h>
#include <linux/profile.h>
#include <linux/timex.h>
#include <linux/notifier.h>
#include <linux/clockchips.h>
#include <linux/gfp.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <vdso/vsyscall.h>
#include <vdso/clocksource.h>
#include <vdso/helpers.h>
#include <asm/facility.h>
#include <asm/delay.h>
#include <asm/div64.h>
#include <asm/vdso.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/vtimer.h>
#include <asm/stp.h>
#include <asm/cio.h>
#include "entry.h"

union tod_clock tod_clock_base __section(".data");
EXPORT_SYMBOL_GPL(tod_clock_base);

u64 clock_comparator_max = -1ULL;
EXPORT_SYMBOL_GPL(clock_comparator_max);

static DEFINE_PER_CPU(struct clock_event_device, comparators);

ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
EXPORT_SYMBOL(s390_epoch_delta_notifier);

unsigned char ptff_function_mask[16];

static unsigned long lpar_offset;
static unsigned long initial_leap_seconds;
static unsigned long tod_steering_end;
static long tod_steering_delta;

/*
 * Get time offsets with PTFF
 */
void __init time_early_init(void)
{
	struct ptff_qto qto;
	struct ptff_qui qui;
	int cs;

	/* Initialize TOD steering parameters */
	tod_steering_end = tod_clock_base.tod;
	for (cs = 0; cs < CS_BASES; cs++)
		vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;

	if (!test_facility(28))
		return;

	ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF);

	/* get LPAR offset */
	if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
		lpar_offset = qto.tod_epoch_difference;

	/* get initial leap seconds */
	if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
		initial_leap_seconds = (unsigned long)
			((long) qui.old_leap * 4096000000L);
}

unsigned long long noinstr sched_clock_noinstr(void)
{
	return tod_to_ns(__get_tod_clock_monotonic());
}

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long notrace sched_clock(void)
{
	return tod_to_ns(get_tod_clock_monotonic());
}
NOKPROBE_SYMBOL(sched_clock);

static void ext_to_timespec64(union tod_clock *clk, struct timespec64 *xt)
{
	unsigned long rem, sec, nsec;

	sec = clk->us;
	rem = do_div(sec, 1000000);
	nsec = ((clk->sus + (rem << 12)) * 125) >> 9;
	xt->tv_sec = sec;
	xt->tv_nsec = nsec;
}

void clock_comparator_work(void)
{
	struct clock_event_device *cd;

	get_lowcore()->clock_comparator = clock_comparator_max;
	cd = this_cpu_ptr(&comparators);
	cd->event_handler(cd);
}

static int s390_next_event(unsigned long delta,
			   struct clock_event_device *evt)
{
	get_lowcore()->clock_comparator = get_tod_clock() + delta;
	set_clock_comparator(get_lowcore()->clock_comparator);
	return 0;
}

/*
 * Set up lowcore and control register of the current cpu to
 * enable TOD clock and clock comparator interrupts.
 */
void init_cpu_timer(void)
{
	struct clock_event_device *cd;
	int cpu;

	get_lowcore()->clock_comparator = clock_comparator_max;
	set_clock_comparator(get_lowcore()->clock_comparator);

	cpu = smp_processor_id();
	cd = &per_cpu(comparators, cpu);
	cd->name		= "comparator";
	cd->features		= CLOCK_EVT_FEAT_ONESHOT;
	cd->mult		= 16777;
	cd->shift		= 12;
	cd->min_delta_ns	= 1;
	cd->min_delta_ticks	= 1;
	cd->max_delta_ns	= LONG_MAX;
	cd->max_delta_ticks	= ULONG_MAX;
	cd->rating		= 400;
	cd->cpumask		= cpumask_of(cpu);
	cd->set_next_event	= s390_next_event;

	clockevents_register_device(cd