// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020 Western Digital Corporation or its affiliates.
*
* Most of the M-mode (i.e. NoMMU) RISC-V systems usually have a
* CLINT MMIO timer device.
*/
#define pr_fmt(fmt) "clint: " fmt
#include <linux/bitops.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/sched_clock.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/of_irq.h>
#include <linux/smp.h>
#include <linux/timex.h>
#ifndef CONFIG_RISCV_M_MODE
#include <asm/clint.h>
#endif
#define CLINT_IPI_OFF 0
#define CLINT_TIMER_CMP_OFF 0x4000
#define CLINT_TIMER_VAL_OFF 0xbff8
/* CLINT manages IPI and Timer for RISC-V M-mode */
static u32 __iomem *clint_ipi_base;
static unsigned int clint_ipi_irq;
static u64 __iomem *clint_timer_cmp;
static u64 __iomem *clint_timer_val;
static unsigned long clint_timer_freq;
static unsigned int clint_timer_irq;
#ifdef CONFIG_RISCV_M_MODE
u64 __iomem *clint_time_val;
EXPORT_SYMBOL(clint_time_val);
#endif
#ifdef CONFIG_SMP
static void clint_send_ipi(unsigned int cpu)
{
writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu));
}
static void clint_clear_ipi(void)
{
writel(0, clint_ipi_base + cpuid_to_hartid_map(smp_processor_id()));
}
static void clint_ipi_interrupt(struct irq_desc *desc)
{
struct irq_chip *chip = irq_desc_get_chip(desc);
chained_irq_enter(chip, desc);
clint_clear_ipi();
ipi_mux_process();
chained_irq_exit(chip, desc);
}
#endif
#ifdef CONFIG_64BIT
#define clint_get_cycles() readq_relaxed(clint_timer_val)
#else
#define clint_get_cycles() readl_relaxed(clint_timer_val)
#define clint_get_cycles_hi() readl_relaxed(((u32 *)clint_timer_val) + 1)
#endif
#ifdef CONFIG_64BIT
static u64 notrace clint_get_cycles64(void)
{
return clint_get_cycles();
}
#else /* CONFIG_64BIT */
static u64 notrace clint_get_cycles64(void)
{
u32 hi, lo;
do {
hi = clint_get_cycles_hi();
lo = clint_get_cycles();
} while (hi != clint_get_cycles_hi());
return ((u64)hi << 32) | lo;
}
#endif /* CONFIG_64BIT */
static u64 clint_rdtime(struct clocksource *cs)
{
return clint_get_cycles64();
}
static struct clocksource clint_clocksource = {
.name = "clint_clocksource",
.rating = 300,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.read = clint_rdtime,
};
static int clint_clock_next_event(unsigned long delta,
struct clock_event_device *ce)
{
void __iomem *r = clint_timer_cmp +
cpuid_to_hartid_map(smp_processor_id());
csr_set(CSR_IE, IE_TIE);
writeq_relaxed(clint_get_cycles64() + delta, r);
return 0;
}
static DEFINE_PER_CPU(struct clock_event_device, clint_clock_event) = {
.name = "clint_clockevent",
.features = CLOCK_EVT_FEAT_ONESHOT,
.rating = 100,
.set_next_event = clint_clock_next_event,
};
static int clint_timer_starting_cpu(unsigned int cpu)
{
struct clock_event_device *ce = per_cpu_ptr(&clint_clock_event, cpu);
ce->cpumask = cpumask_of(cpu);
clockevents_config_and_register(ce, clint_timer_freq, 100, ULONG_MAX);
enable_percpu_irq(clint_timer_irq,
irq_get_trigger_type(clint_timer_irq));
enable_percpu_irq(clint_ipi_irq,
irq_get_trigger_type(clint_ipi_irq));
return 0;
}
static int clint_timer_dying_cpu(unsigned int cpu)
{
disable_percpu_irq(clint_timer_irq);
/*
* Don't disable IPI when CPU goes offline because
* the masking/unmasking of virtual IPIs is done
* via generic IPI-Mux
*/
return 0;
}
static irqreturn_t clint_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evdev = this_cpu_ptr(&clint_clock_event);
csr_clear(CSR_IE, IE_TIE);
evdev->event_handler(evdev);
return IRQ_HANDLED;
}
static int __init clint_timer_init_dt(struct device_node *np)
{
int rc;
u32 i, nr_irqs;
void __iomem *base;
struct of_phandle_args oirq;
/*
* Ensure that CLINT device interrupts are either RV_IRQ_TIMER or
* RV_IRQ_SOFT. If it's anything else then we ignore the device.
*/
nr_irqs = of_irq_count(np);
for (i = 0; i < nr_irqs; i++) {
if (of_irq_parse_one(np, i, &oirq)) {
pr_err("%pOFP: failed to parse irq %d.\n", np, i);
continue;
}
if ((oirq.args_count != 1) ||
(oirq.args[0] != RV_IRQ_TIMER &&
oirq.args[0] != RV_IRQ_SOFT)) {
pr_err("%pOFP: invalid irq %d (hwirq %d)\n",
np, i, oirq.args[0]);
return -ENODEV;
}
/* Find parent irq domain and map ipi irq */
if (!clint_ipi_irq &&
oirq.args[0] == RV_IRQ_SOFT &&
irq_find_host(oirq.np))
clint_ipi_irq = irq_of_parse_and_map(np, i);
/* Find parent irq domain and map timer irq */
if (!clint_timer_irq &&
oirq.args[0] == RV_IRQ_TIMER &&
irq_find_host(oirq.np))
clint_timer_irq = irq_of_parse_and_map(np, i);
}
/* If CLINT ipi or timer irq not found then fail */
if (!clint_ipi_irq || !clint_timer_irq) {
pr_err("%pOFP: ipi/timer irq not found\n", np);
return -ENODEV;
}
base = of_iomap(np, 0);
if (!base) {
pr_err("%pOFP: could not map registers\n", np);
return -ENODEV;
}
clint_ipi_base = base + CLINT_IPI_OFF;
clint_timer_cmp = base + CLINT_TIMER_CMP_OFF;
clint_timer_val = base + CLINT_TIMER_VAL_OFF;
clint_timer_freq = riscv_timebase;
#ifdef CONFIG_RISCV_M_MODE
/*
* Yes, that's an odd naming scheme. time_val is public, but hopefully
* will die in favor of something cleaner.
*/
clint_time_val = clint_timer_val;
#endif
pr_info("%pOFP: timer running at %ld Hz\n", np, clint_timer_freq);
rc = clocksource_register_hz(&clint_clocksource, clint_timer_freq);
if (rc) {
pr_err("%pOFP: clocksource register failed [%d]\n", np, rc);
goto fail_iounmap;
}
sched_clock_register(clint_get_cycles64, 64, clint_timer_freq);
rc = request_percpu_irq(clint_timer_irq, clint_timer_interrupt,
"clint-timer", &clint_clock_event);
if (rc) {
pr_err("registering percpu irq failed [%d]\n", rc);
goto fail_iounmap;
}
#ifdef CONFIG_SMP
rc = ipi_mux_create(BITS_PER_BYTE, clint_send_ipi);
if (rc <= 0) {
pr_err("unable to create muxed IPIs\n");
rc = (rc < 0) ? rc : -ENODEV;
goto fail_free_irq;
}
irq_set_chained_handler(clint_ipi_irq, clint_ipi_interrupt);
riscv_ipi_set_virq_range(rc, BITS_PER_BYTE);
clint_clear_ipi();
#endif
rc = cpuhp_setup_state(CPUHP_AP_CLINT_TIMER_STARTING,
"clockevents/clint/timer:starting",
clint_timer_starting_cpu,
clint_timer_dying_cpu);
if (rc) {
pr_err("%pOFP: cpuhp setup state failed [%d]\n", np, rc);
goto fail_free_irq;
}
return 0;
fail_free_irq:
free_percpu_irq(clint_timer_irq, &clint_clock_event);
fail_iounmap:
iounmap(base);
return rc;
}
TIMER_OF_DECLARE(clint_timer, "riscv,clint0", clint_timer_init_dt);
TIMER_OF_DECLARE(clint_timer1, "sifive,clint0", clint_timer_init_dt);
Codebase Browser
linux