// SPDX-License-Identifier: GPL-2.0/* * Copyright (C) 2012 Regents of the University of California * Copyright (C) 2017 SiFive */#include <linux/clocksource.h>#include <linux/clockchips.h>#include <linux/cpu.h>#include <linux/delay.h>#include <linux/irq.h>#include <linux/sched_clock.h>#include <asm/smp.h>#include <asm/sbi.h> /* * All RISC-V systems have a timer attached to every hart.  These timers can be * read by the 'rdcycle' pseudo instruction, and can use the SBI to setup * events.  In order to abstract the architecture-specific timer reading and * setting functions away from the clock event insertion code, we provide * function pointers to the clockevent subsystem that perform two basic * operations: rdtime() reads the timer on the current CPU, and * next_event(delta) sets the next timer event to 'delta' cycles in the future. * As the timers are inherently a per-cpu resource, these callbacks perform * operations on the current hart.  There is guaranteed to be exactly one timer * per hart on all RISC-V systems. */ static int riscv_clock_next_event(unsigned long delta,		struct clock_event_device *ce){	csr_set(sie, SIE_STIE);	sbi_set_timer(get_cycles64() + delta);	return 0;} static DEFINE_PER_CPU(struct clock_event_device, riscv_clock_event) = {	.name			= "riscv_timer_clockevent",	.features		= CLOCK_EVT_FEAT_ONESHOT,	.rating			= 100,	.set_next_event		= riscv_clock_next_event,}; /* * It is guaranteed that all the timers across all the harts are synchronized * within one tick of each other, so while this could technically go * backwards when hopping between CPUs, practically it won't happen. */static unsigned long long riscv_clocksource_rdtime(struct clocksource *cs){	return get_cycles64();} static u64 riscv_sched_clock(void){	return get_cycles64();} static DEFINE_PER_CPU(struct clocksource, riscv_clocksource) = {	.name		= "riscv_clocksource",	.rating		= 300,	.mask		= CLOCKSOURCE_MASK(64),	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,	.read		= riscv_clocksource_rdtime,}; static int riscv_timer_starting_cpu(unsigned int cpu){	struct clock_event_device *ce = per_cpu_ptr(&riscv_clock_event, cpu); 	ce->cpumask = cpumask_of(cpu);	clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff); 	csr_set(sie, SIE_STIE);	return 0;} static int riscv_timer_dying_cpu(unsigned int cpu){	csr_clear(sie, SIE_STIE);	return 0;} /* called directly from the low-level interrupt handler */void riscv_timer_interrupt(void){	struct clock_event_device *evdev = this_cpu_ptr(&riscv_clock_event); 	csr_clear(sie, SIE_STIE);	evdev->event_handler(evdev);} static int __init riscv_timer_init_dt(struct device_node *n){	int cpuid, hartid, error;	struct clocksource *cs; 	hartid = riscv_of_processor_hartid(n);	if (hartid < 0) {		pr_warn("Not valid hartid for node [%pOF] error = [%d]\n",			n, hartid);		return hartid;	} 	cpuid = riscv_hartid_to_cpuid(hartid);	if (cpuid < 0) {		pr_warn("Invalid cpuid for hartid [%d]\n", hartid);		return cpuid;	} 	if (cpuid != smp_processor_id())		return 0; 	pr_info("%s: Registering clocksource cpuid [%d] hartid [%d]\n",	       __func__, cpuid, hartid);	cs = per_cpu_ptr(&riscv_clocksource, cpuid);	error = clocksource_register_hz(cs, riscv_timebase);	if (error) {		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",		       error, cpuid);		return error;	} 	sched_clock_register(riscv_sched_clock, 64, riscv_timebase); 	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,			 "clockevents/riscv/timer:starting",			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);	if (error)		pr_err("cpu hp setup state failed for RISCV timer [%d]\n",		       error);	return error;} TIMER_OF_DECLARE(riscv_timer, "riscv", riscv_timer_init_dt);