// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2012 Regents of the University of California
* Copyright (C) 2017 SiFive
*
* All RISC-V systems have a timer attached to every hart. These timers can
* either be read from the "time" and "timeh" CSRs, and can use the SBI to
* setup events, or directly accessed using MMIO registers.
*/
#define pr_fmt(fmt) "riscv-timer: " fmt
#include <linux/acpi.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/sched_clock.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/limits.h>
#include <clocksource/timer-riscv.h>
#include <asm/smp.h>
#include <asm/cpufeature.h>
#include <asm/sbi.h>
#include <asm/timex.h>
static DEFINE_STATIC_KEY_FALSE(riscv_sstc_available);
static bool riscv_timer_cannot_wake_cpu;
static void riscv_clock_event_stop(void)
{
if (static_branch_likely(&riscv_sstc_available)) {
csr_write(CSR_STIMECMP, ULONG_MAX);
if (IS_ENABLED(CONFIG_32BIT))
csr_write(CSR_STIMECMPH, ULONG_MAX);
} else {
sbi_set_timer(U64_MAX);
}
}
static int riscv_clock_next_event(unsigned long delta,
struct clock_event_device *ce)
{
u64 next_tval = get_cycles64() + delta;
if (static_branch_likely(&riscv_sstc_available)) {
#if defined(CONFIG_32BIT)
csr_write(CSR_STIMECMP, next_tval & 0xFFFFFFFF);
csr_write(CSR_STIMECMPH, next_tval >> 32);
#else
csr_write(CSR_STIMECMP, next_tval);
#endif
} else
sbi_set_timer(next_tval);
return 0;
}
static int riscv_clock_shutdown(struct clock_event_device *evt)
{
riscv_clock_event_stop();
return 0;
}
static unsigned int riscv_clock_event_irq;
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,
.set_state_shutdown = riscv_clock_shutdown,
};
/*
* 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 notrace riscv_sched_clock(void)
{
return get_cycles64();
}
static struct clocksource riscv_clocksource = {
.name = "riscv_clocksource",
.rating = 400,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.read = riscv_clocksource_rdtime,
#if IS_ENABLED(CONFIG_GENERIC_GETTIMEOFDAY)
.vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER,
#else
.vdso_clock_mode = VDSO_CLOCKMODE_NONE,
#endif
};
static int riscv_timer_starting_cpu(unsigned int cpu)
{
struct clock_event_device *ce = per_cpu_ptr(&riscv_clock_event, cpu);
/* Clear timer interrupt */
riscv_clock_event_stop();
ce->cpumask = cpumask_of(cpu);
ce->irq = riscv_clock_event_irq;
if (riscv_timer_cannot_wake_cpu)
ce->features |= CLOCK_EVT_FEAT_C3STOP;
if (static_branch_likely(&riscv_sstc_available))
ce->rating = 450;
clockevents_config_and_register(ce, riscv_timebase, 100, ULONG_MAX);
enable_percpu_irq(riscv_clock_event_irq,
irq_get_trigger_type(riscv_clock_event_irq));
return 0;
}
static int riscv_timer_dying_cpu(unsigned int cpu)
{
disable_percpu_irq(riscv_clock_event_irq);
return 0;
}
void riscv_cs_get_mult_shift(u32 *mult, u32 *shift)
{
*mult = riscv_clocksource.mult;
*shift = riscv_clocksource.shift;
}
EXPORT_SYMBOL_GPL(riscv_cs_get_mult_shift);
/* called directly from the low-level interrupt handler */
static irqreturn_t riscv_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evdev = this_cpu_ptr(&riscv_clock_event);
riscv_clock_event_stop();
evdev->event_handler(evdev);
return IRQ_HANDLED;
}
static int __init riscv_timer_init_common(void)
{
int error;
struct irq_domain *domain;
struct fwnode_handle *intc_fwnode = riscv_get_intc_hwnode();
domain = irq_find_matching_fwnode(intc_fwnode, DOMAIN_BUS_ANY);
if (!domain) {
pr_err("Failed to find irq_domain for INTC node [%pfwP]\n",
intc_fwnode);
return -ENODEV;
}
riscv_clock_event_irq = irq_create_mapping(domain, RV_IRQ_TIMER);
if (!riscv_clock_event_irq) {
pr_err("Failed to map timer interrupt for node [%pfwP]\n", intc_fwnode);
return -ENODEV;
}
error = clocksource_register_hz(&riscv_clocksource, riscv_timebase);
if (error) {
pr_err("RISCV timer registration failed [%d]\n", error);
return error;
}
sched_clock_register(riscv_sched_clock, 64, riscv_timebase);
error = request_percpu_irq(riscv_clock_event_irq,
riscv_timer_interrupt,
"riscv-timer", &riscv_clock_event);
if (error) {
pr_err("registering percpu irq failed [%d]\n", error);
return error;
}
if (riscv_isa_extension_available(NULL, SSTC)) {
pr_info("Timer interrupt in S-mode is available via sstc extension\n");
static_branch_enable(&riscv_sstc_available);
}
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;
}
static int __init riscv_timer_init_dt(struct device_node *n)
{
int cpuid, error;
unsigned long hartid;
struct device_node *child;
error = riscv_of_processor_hartid(n, &hartid);
if (error < 0) {
pr_warn("Invalid hartid for node [%pOF] error = [%lu]\n",
n, hartid);
return error;
}
cpuid = riscv_hartid_to_cpuid(hartid);
if (cpuid < 0) {
pr_warn("Invalid cpuid for hartid [%lu]\n", hartid);
return cpuid;
}
if (cpuid != smp_processor_id())
return 0;
child = of_find_compatible_node(NULL, NULL, "riscv,timer");
if (child) {
riscv_timer_cannot_wake_cpu = of_property_read_bool(child,
"riscv,timer-cannot-wake-cpu");
of_node_put(child);
}
return riscv_timer_init_common();
}
TIMER_OF_DECLARE(riscv_timer, "riscv", riscv_timer_init_dt);
#ifdef CONFIG_ACPI
static int __init riscv_timer_acpi_init(struct acpi_table_header *table)
{
struct acpi_table_rhct *rhct = (struct acpi_table_rhct *)table;
riscv_timer_cannot_wake_cpu = rhct->flags & ACPI_RHCT_TIMER_CANNOT_WAKEUP_CPU;
return riscv_timer_init_common();
}
TIMER_ACPI_DECLARE(aclint_mtimer, ACPI_SIG_RHCT, riscv_timer_acpi_init);
#endif
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