1 files changed, 174 insertions, 39 deletions

diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index 431892200a08..4d7cf338824a 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -2,42 +2,78 @@
 /*
  * 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>
 
-/*
- * 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 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)
 {
-	csr_set(sie, SIE_STIE);
-	sbi_set_timer(get_cycles64() + delta);
+	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,
 };
 
 /*
@@ -50,69 +86,168 @@ static unsigned long long riscv_clocksource_rdtime(struct clocksource *cs)
 	return get_cycles64();
 }
 
-static u64 riscv_sched_clock(void)
+static u64 notrace riscv_sched_clock(void)
 {
 	return get_cycles64();
 }
 
-static DEFINE_PER_CPU(struct clocksource, riscv_clocksource) = {
+static struct clocksource riscv_clocksource = {
 	.name		= "riscv_clocksource",
-	.rating		= 300,
-	.mask		= CLOCKSOURCE_MASK(BITS_PER_LONG),
+	.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);
 
-	ce->cpumask = cpumask_of(cpu);
-	clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff);
+	/* Clear timer interrupt */
+	riscv_clock_event_stop();
 
-	csr_set(sie, SIE_STIE);
+	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)
 {
-	csr_clear(sie, SIE_STIE);
+	/*
+	 * Stop the timer when the cpu is going to be offline otherwise
+	 * the timer interrupt may be pending while performing power-down.
+	 */
+	riscv_clock_event_stop();
+	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 */
-void riscv_timer_interrupt(void)
+static irqreturn_t riscv_timer_interrupt(int irq, void *dev_id)
 {
 	struct clock_event_device *evdev = this_cpu_ptr(&riscv_clock_event);
 
-	csr_clear(sie, SIE_STIE);
+	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, hartid, error;
-	struct clocksource *cs;
+	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;
+	}
 
-	hartid = riscv_of_processor_hartid(n);
 	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;
 
-	cs = per_cpu_ptr(&riscv_clocksource, cpuid);
-	clocksource_register_hz(cs, riscv_timebase);
-
-	sched_clock_register(riscv_sched_clock,
-			BITS_PER_LONG, riscv_timebase);
+	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);
+	}
 
-	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("RISCV timer register failed [%d] for cpu = [%d]\n",
-		       error, cpuid);
-	return error;
+	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