diff options
Diffstat (limited to 'arch/parisc/kernel/time.c')
| -rw-r--r-- | arch/parisc/kernel/time.c | 261 |
1 files changed, 105 insertions, 156 deletions
diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c index 9714fbd7c42d..c17e2249115f 100644 --- a/arch/parisc/kernel/time.c +++ b/arch/parisc/kernel/time.c @@ -1,166 +1,119 @@ // SPDX-License-Identifier: GPL-2.0 /* - * linux/arch/parisc/kernel/time.c + * Common time service routines for parisc machines. + * based on arch/loongarch/kernel/time.c * - * Copyright (C) 1991, 1992, 1995 Linus Torvalds - * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King - * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org) - * - * 1994-07-02 Alan Modra - * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime - * 1998-12-20 Updated NTP code according to technical memorandum Jan '96 - * "A Kernel Model for Precision Timekeeping" by Dave Mills + * Copyright (C) 2024 Helge Deller <deller@gmx.de> */ -#include <linux/errno.h> -#include <linux/module.h> -#include <linux/rtc.h> -#include <linux/sched.h> -#include <linux/sched/clock.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/time.h> +#include <linux/clockchips.h> +#include <linux/delay.h> +#include <linux/export.h> #include <linux/init.h> -#include <linux/smp.h> -#include <linux/profile.h> -#include <linux/clocksource.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/sched_clock.h> +#include <linux/spinlock.h> +#include <linux/rtc.h> #include <linux/platform_device.h> -#include <linux/ftrace.h> +#include <asm/processor.h> -#include <linux/uaccess.h> -#include <asm/io.h> -#include <asm/irq.h> -#include <asm/page.h> -#include <asm/param.h> -#include <asm/pdc.h> -#include <asm/led.h> +static u64 cr16_clock_freq; +static unsigned long clocktick; -#include <linux/timex.h> +int time_keeper_id; /* CPU used for timekeeping */ -int time_keeper_id __read_mostly; /* CPU used for timekeeping. */ +static DEFINE_PER_CPU(struct clock_event_device, parisc_clockevent_device); -static unsigned long clocktick __ro_after_init; /* timer cycles per tick */ +static void parisc_event_handler(struct clock_event_device *dev) +{ +} -/* - * We keep time on PA-RISC Linux by using the Interval Timer which is - * a pair of registers; one is read-only and one is write-only; both - * accessed through CR16. The read-only register is 32 or 64 bits wide, - * and increments by 1 every CPU clock tick. The architecture only - * guarantees us a rate between 0.5 and 2, but all implementations use a - * rate of 1. The write-only register is 32-bits wide. When the lowest - * 32 bits of the read-only register compare equal to the write-only - * register, it raises a maskable external interrupt. Each processor has - * an Interval Timer of its own and they are not synchronised. - * - * We want to generate an interrupt every 1/HZ seconds. So we program - * CR16 to interrupt every @clocktick cycles. The it_value in cpu_data - * is programmed with the intended time of the next tick. We can be - * held off for an arbitrarily long period of time by interrupts being - * disabled, so we may miss one or more ticks. - */ -irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id) +static int parisc_timer_next_event(unsigned long delta, struct clock_event_device *evt) { - unsigned long now; - unsigned long next_tick; - unsigned long ticks_elapsed = 0; - unsigned int cpu = smp_processor_id(); - struct cpuinfo_parisc *cpuinfo = &per_cpu(cpu_data, cpu); - - /* gcc can optimize for "read-only" case with a local clocktick */ - unsigned long cpt = clocktick; - - /* Initialize next_tick to the old expected tick time. */ - next_tick = cpuinfo->it_value; - - /* Calculate how many ticks have elapsed. */ - now = mfctl(16); - do { - ++ticks_elapsed; - next_tick += cpt; - } while (next_tick - now > cpt); - - /* Store (in CR16 cycles) up to when we are accounting right now. */ - cpuinfo->it_value = next_tick; - - /* Go do system house keeping. */ - if (IS_ENABLED(CONFIG_SMP) && (cpu != time_keeper_id)) - ticks_elapsed = 0; - legacy_timer_tick(ticks_elapsed); - - /* Skip clockticks on purpose if we know we would miss those. - * The new CR16 must be "later" than current CR16 otherwise - * itimer would not fire until CR16 wrapped - e.g 4 seconds - * later on a 1Ghz processor. We'll account for the missed - * ticks on the next timer interrupt. - * We want IT to fire modulo clocktick even if we miss/skip some. - * But those interrupts don't in fact get delivered that regularly. - * - * "next_tick - now" will always give the difference regardless - * if one or the other wrapped. If "now" is "bigger" we'll end up - * with a very large unsigned number. - */ - now = mfctl(16); - while (next_tick - now > cpt) - next_tick += cpt; - - /* Program the IT when to deliver the next interrupt. - * Only bottom 32-bits of next_tick are writable in CR16! - * Timer interrupt will be delivered at least a few hundred cycles - * after the IT fires, so if we are too close (<= 8000 cycles) to the - * next cycle, simply skip it. - */ - if (next_tick - now <= 8000) - next_tick += cpt; - mtctl(next_tick, 16); + unsigned long new_cr16; - return IRQ_HANDLED; -} + new_cr16 = mfctl(16) + delta; + mtctl(new_cr16, 16); + return 0; +} -unsigned long profile_pc(struct pt_regs *regs) +irqreturn_t timer_interrupt(int irq, void *data) { - unsigned long pc = instruction_pointer(regs); + struct clock_event_device *cd; + int cpu = smp_processor_id(); - if (regs->gr[0] & PSW_N) - pc -= 4; + cd = &per_cpu(parisc_clockevent_device, cpu); -#ifdef CONFIG_SMP - if (in_lock_functions(pc)) - pc = regs->gr[2]; -#endif + if (clockevent_state_periodic(cd)) + parisc_timer_next_event(clocktick, cd); - return pc; + if (clockevent_state_periodic(cd) || clockevent_state_oneshot(cd)) + cd->event_handler(cd); + + return IRQ_HANDLED; } -EXPORT_SYMBOL(profile_pc); +static int parisc_set_state_oneshot(struct clock_event_device *evt) +{ + parisc_timer_next_event(clocktick, evt); -/* clock source code */ + return 0; +} -static u64 notrace read_cr16(struct clocksource *cs) +static int parisc_set_state_periodic(struct clock_event_device *evt) { - return get_cycles(); + parisc_timer_next_event(clocktick, evt); + + return 0; } -static struct clocksource clocksource_cr16 = { - .name = "cr16", - .rating = 300, - .read = read_cr16, - .mask = CLOCKSOURCE_MASK(BITS_PER_LONG), - .flags = CLOCK_SOURCE_IS_CONTINUOUS, -}; +static int parisc_set_state_shutdown(struct clock_event_device *evt) +{ + return 0; +} -void start_cpu_itimer(void) +void parisc_clockevent_init(void) { unsigned int cpu = smp_processor_id(); - unsigned long next_tick = mfctl(16) + clocktick; + unsigned long min_delta = 0x600; /* XXX */ + unsigned long max_delta = (1UL << (BITS_PER_LONG - 1)); + struct clock_event_device *cd; + + cd = &per_cpu(parisc_clockevent_device, cpu); + + cd->name = "cr16_clockevent"; + cd->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_PERCPU; + + cd->irq = TIMER_IRQ; + cd->rating = 320; + cd->cpumask = cpumask_of(cpu); + cd->set_state_oneshot = parisc_set_state_oneshot; + cd->set_state_oneshot_stopped = parisc_set_state_shutdown; + cd->set_state_periodic = parisc_set_state_periodic; + cd->set_state_shutdown = parisc_set_state_shutdown; + cd->set_next_event = parisc_timer_next_event; + cd->event_handler = parisc_event_handler; + + clockevents_config_and_register(cd, cr16_clock_freq, min_delta, max_delta); +} + +unsigned long notrace profile_pc(struct pt_regs *regs) +{ + unsigned long pc = instruction_pointer(regs); - mtctl(next_tick, 16); /* kick off Interval Timer (CR16) */ + if (regs->gr[0] & PSW_N) + pc -= 4; + +#ifdef CONFIG_SMP + if (in_lock_functions(pc)) + pc = regs->gr[2]; +#endif - per_cpu(cpu_data, cpu).it_value = next_tick; + return pc; } +EXPORT_SYMBOL(profile_pc); #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC) static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm) @@ -224,12 +177,27 @@ void read_persistent_clock64(struct timespec64 *ts) } } - static u64 notrace read_cr16_sched_clock(void) { return get_cycles(); } +static u64 notrace read_cr16(struct clocksource *cs) +{ + return get_cycles(); +} + +static struct clocksource clocksource_cr16 = { + .name = "cr16", + .rating = 300, + .read = read_cr16, + .mask = CLOCKSOURCE_MASK(BITS_PER_LONG), + .flags = CLOCK_SOURCE_IS_CONTINUOUS | + CLOCK_SOURCE_VALID_FOR_HRES | + CLOCK_SOURCE_MUST_VERIFY | + CLOCK_SOURCE_VERIFY_PERCPU, +}; + /* * timer interrupt and sched_clock() initialization @@ -237,33 +205,14 @@ static u64 notrace read_cr16_sched_clock(void) void __init time_init(void) { - unsigned long cr16_hz; - - clocktick = (100 * PAGE0->mem_10msec) / HZ; - start_cpu_itimer(); /* get CPU 0 started */ - - cr16_hz = 100 * PAGE0->mem_10msec; /* Hz */ + cr16_clock_freq = 100 * PAGE0->mem_10msec; /* Hz */ + clocktick = cr16_clock_freq / HZ; /* register as sched_clock source */ - sched_clock_register(read_cr16_sched_clock, BITS_PER_LONG, cr16_hz); -} + sched_clock_register(read_cr16_sched_clock, BITS_PER_LONG, cr16_clock_freq); -static int __init init_cr16_clocksource(void) -{ - /* - * The cr16 interval timers are not synchronized across CPUs. - */ - if (num_online_cpus() > 1 && !running_on_qemu) { - clocksource_cr16.name = "cr16_unstable"; - clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE; - clocksource_cr16.rating = 0; - } + parisc_clockevent_init(); /* register at clocksource framework */ - clocksource_register_hz(&clocksource_cr16, - 100 * PAGE0->mem_10msec); - - return 0; + clocksource_register_hz(&clocksource_cr16, cr16_clock_freq); } - -device_initcall(init_cr16_clocksource); |