From: Anup Patel <anup@brainfault.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Palmer Dabbelt <palmer@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>
Cc: Christoph Hellwig <hch@infradead.org>,
Atish Patra <atish.patra@wdc.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
Anup Patel <anup@brainfault.org>
Subject: [PATCH v2 2/2] clocksource: riscv_timer: Provide sched_clock
Date: Tue, 4 Dec 2018 15:59:52 +0530 [thread overview]
Message-ID: <20181204102952.21297-3-anup@brainfault.org> (raw)
In-Reply-To: <20181204102952.21297-1-anup@brainfault.org>
Currently, we don't have a sched_clock registered for RISC-V systems.
This means Linux time keeping will use jiffies (running at HZ) as the
default sched_clock.
To avoid this, we explicity provide sched_clock using RISC-V rdtime
instruction (similar to riscv_timer clocksource).
Signed-off-by: Anup Patel <anup@brainfault.org>
---
drivers/clocksource/Kconfig | 2 +-
drivers/clocksource/riscv_timer.c | 9 +++++++++
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 55c77e44bb2d..19649abd7c75 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -611,7 +611,7 @@ config ATCPIT100_TIMER
config RISCV_TIMER
bool "Timer for the RISC-V platform"
- depends on RISCV
+ depends on GENERIC_SCHED_CLOCK && RISCV
default y
select TIMER_PROBE
select TIMER_OF
diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
index 084e97dc10ed..431892200a08 100644
--- a/drivers/clocksource/riscv_timer.c
+++ b/drivers/clocksource/riscv_timer.c
@@ -8,6 +8,7 @@
#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>
@@ -49,6 +50,11 @@ 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,
@@ -97,6 +103,9 @@ static int __init riscv_timer_init_dt(struct device_node *n)
cs = per_cpu_ptr(&riscv_clocksource, cpuid);
clocksource_register_hz(cs, riscv_timebase);
+ sched_clock_register(riscv_sched_clock,
+ BITS_PER_LONG, riscv_timebase);
+
error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
"clockevents/riscv/timer:starting",
riscv_timer_starting_cpu, riscv_timer_dying_cpu);
--
2.17.1
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next prev parent reply other threads:[~2018-12-04 10:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 10:29 [PATCH v2 0/2] Provide sched_clock for riscv_timer Anup Patel
2018-12-04 10:29 ` [PATCH v2 1/2] RISC-V: Select GENERIC_SCHED_CLOCK for clocksource drivers Anup Patel
2018-12-07 17:58 ` Palmer Dabbelt
2018-12-04 10:29 ` Anup Patel [this message]
2018-12-07 17:58 ` [PATCH v2 2/2] clocksource: riscv_timer: Provide sched_clock Palmer Dabbelt
2018-12-07 17:59 ` [PATCH v2 0/2] Provide sched_clock for riscv_timer Palmer Dabbelt
2018-12-09 16:30 ` Daniel Lezcano
2018-12-10 17:31 ` Palmer Dabbelt
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