diff options
Diffstat (limited to 'arch/loongarch/kernel/time.c')
| -rw-r--r-- | arch/loongarch/kernel/time.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c new file mode 100644 index 000000000000..fe6823875895 --- /dev/null +++ b/arch/loongarch/kernel/time.c @@ -0,0 +1,214 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Common time service routines for LoongArch machines. + * + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited + */ +#include <linux/clockchips.h> +#include <linux/delay.h> +#include <linux/export.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/sched_clock.h> +#include <linux/spinlock.h> + +#include <asm/cpu-features.h> +#include <asm/loongarch.h> +#include <asm/time.h> + +u64 cpu_clock_freq; +EXPORT_SYMBOL(cpu_clock_freq); +u64 const_clock_freq; +EXPORT_SYMBOL(const_clock_freq); + +static DEFINE_RAW_SPINLOCK(state_lock); +static DEFINE_PER_CPU(struct clock_event_device, constant_clockevent_device); + +static void constant_event_handler(struct clock_event_device *dev) +{ +} + +irqreturn_t constant_timer_interrupt(int irq, void *data) +{ + int cpu = smp_processor_id(); + struct clock_event_device *cd; + + /* Clear Timer Interrupt */ + write_csr_tintclear(CSR_TINTCLR_TI); + cd = &per_cpu(constant_clockevent_device, cpu); + cd->event_handler(cd); + + return IRQ_HANDLED; +} + +static int constant_set_state_oneshot(struct clock_event_device *evt) +{ + unsigned long timer_config; + + raw_spin_lock(&state_lock); + + timer_config = csr_read64(LOONGARCH_CSR_TCFG); + timer_config |= CSR_TCFG_EN; + timer_config &= ~CSR_TCFG_PERIOD; + csr_write64(timer_config, LOONGARCH_CSR_TCFG); + + raw_spin_unlock(&state_lock); + + return 0; +} + +static int constant_set_state_oneshot_stopped(struct clock_event_device *evt) +{ + unsigned long timer_config; + + raw_spin_lock(&state_lock); + + timer_config = csr_read64(LOONGARCH_CSR_TCFG); + timer_config &= ~CSR_TCFG_EN; + csr_write64(timer_config, LOONGARCH_CSR_TCFG); + + raw_spin_unlock(&state_lock); + + return 0; +} + +static int constant_set_state_periodic(struct clock_event_device *evt) +{ + unsigned long period; + unsigned long timer_config; + + raw_spin_lock(&state_lock); + + period = const_clock_freq / HZ; + timer_config = period & CSR_TCFG_VAL; + timer_config |= (CSR_TCFG_PERIOD | CSR_TCFG_EN); + csr_write64(timer_config, LOONGARCH_CSR_TCFG); + + raw_spin_unlock(&state_lock); + + return 0; +} + +static int constant_set_state_shutdown(struct clock_event_device *evt) +{ + return 0; +} + +static int constant_timer_next_event(unsigned long delta, struct clock_event_device *evt) +{ + unsigned long timer_config; + + delta &= CSR_TCFG_VAL; + timer_config = delta | CSR_TCFG_EN; + csr_write64(timer_config, LOONGARCH_CSR_TCFG); + + return 0; +} + +static unsigned long __init get_loops_per_jiffy(void) +{ + unsigned long lpj = (unsigned long)const_clock_freq; + + do_div(lpj, HZ); + + return lpj; +} + +static long init_timeval; + +void sync_counter(void) +{ + /* Ensure counter begin at 0 */ + csr_write64(-init_timeval, LOONGARCH_CSR_CNTC); +} + +int constant_clockevent_init(void) +{ + unsigned int irq; + unsigned int cpu = smp_processor_id(); + unsigned long min_delta = 0x600; + unsigned long max_delta = (1UL << 48) - 1; + struct clock_event_device *cd; + static int timer_irq_installed = 0; + + irq = EXCCODE_TIMER - EXCCODE_INT_START; + + cd = &per_cpu(constant_clockevent_device, cpu); + + cd->name = "Constant"; + cd->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_PERCPU; + + cd->irq = irq; + cd->rating = 320; + cd->cpumask = cpumask_of(cpu); + cd->set_state_oneshot = constant_set_state_oneshot; + cd->set_state_oneshot_stopped = constant_set_state_oneshot_stopped; + cd->set_state_periodic = constant_set_state_periodic; + cd->set_state_shutdown = constant_set_state_shutdown; + cd->set_next_event = constant_timer_next_event; + cd->event_handler = constant_event_handler; + + clockevents_config_and_register(cd, const_clock_freq, min_delta, max_delta); + + if (timer_irq_installed) + return 0; + + timer_irq_installed = 1; + + sync_counter(); + + if (request_irq(irq, constant_timer_interrupt, IRQF_PERCPU | IRQF_TIMER, "timer", NULL)) + pr_err("Failed to request irq %d (timer)\n", irq); + + lpj_fine = get_loops_per_jiffy(); + pr_info("Constant clock event device register\n"); + + return 0; +} + +static u64 read_const_counter(struct clocksource *clk) +{ + return drdtime(); +} + +static u64 native_sched_clock(void) +{ + return read_const_counter(NULL); +} + +static struct clocksource clocksource_const = { + .name = "Constant", + .rating = 400, + .read = read_const_counter, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .vdso_clock_mode = VDSO_CLOCKMODE_CPU, +}; + +int __init constant_clocksource_init(void) +{ + int res; + unsigned long freq = const_clock_freq; + + res = clocksource_register_hz(&clocksource_const, freq); + + sched_clock_register(native_sched_clock, 64, freq); + + pr_info("Constant clock source device register\n"); + + return res; +} + +void __init time_init(void) +{ + if (!cpu_has_cpucfg) + const_clock_freq = cpu_clock_freq; + else + const_clock_freq = calc_const_freq(); + + init_timeval = drdtime() - csr_read64(LOONGARCH_CSR_CNTC); + + constant_clockevent_init(); + constant_clocksource_init(); +} |