[PATCH 0/3] clocksouce/timer-clint|riscv: some improvements

[PATCH 0/3] clocksouce/timer-clint|riscv: some improvements

[Jisheng Zhang]

This series is a simple improvement for timer-clint and timer-riscv:

Add set_state_shutdown for timer-clint, this hook is used when
switching clockevent from timer-clint to another timer.

Add set_state_oneshot_stopped for both timer-clint and timer-riscv,
this hook is to avoid spurious timer interrupts when KTIME_MAX is
usd. Check commit 8fff52fd5093 ("clockevents: Introduce
CLOCK_EVT_STATE_ONESHOT_STOPPED state") for more information.

Jisheng Zhang (3):
  clocksource/drivers/timer-riscv: Add set_state_oneshot_stopped
  clocksource/drivers/timer-clint: Add set_state_shutdown
  clocksource/drivers/timer-clint: Add set_state_oneshot_stopped

 drivers/clocksource/timer-clint.c | 19 +++++++++++++++----
 drivers/clocksource/timer-riscv.c | 11 ++++++-----
 2 files changed, 21 insertions(+), 9 deletions(-)

-- 
2.43.0


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[PATCH 1/3] clocksource/drivers/timer-riscv: Add set_state_oneshot_stopped

[Jisheng Zhang]

To avoid spurious timer interrupts when KTIME_MAX is used, we need to
configure set_state_oneshot_stopped(). Although implementing this is
optional, it still affects things like power management for the extra
timer interrupt.

Check commit 8fff52fd5093 ("clockevents: Introduce
CLOCK_EVT_STATE_ONESHOT_STOPPED state") for more information.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 drivers/clocksource/timer-riscv.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index 48ce50c5f5e6..e661fc037337 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -69,11 +69,12 @@ static int riscv_clock_shutdown(struct clock_event_device *evt)
 
 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,
+	.name				= "riscv_timer_clockevent",
+	.features			= CLOCK_EVT_FEAT_ONESHOT,
+	.rating				= 100,
+	.set_next_event			= riscv_clock_next_event,
+	.set_state_shutdown		= riscv_clock_shutdown,
+	.set_state_oneshot_stopped	= riscv_clock_shutdown,
 };
 
 /*
-- 
2.43.0


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[PATCH 2/3] clocksource/drivers/timer-clint: Add set_state_shutdown

[Jisheng Zhang]

Add clocksource detach/shutdown callback to disable RISC-V timer interrupt when
switching out clockevent from clint timer to another timer.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 drivers/clocksource/timer-clint.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c
index 09fd292eb83d..56cf6c672e6d 100644
--- a/drivers/clocksource/timer-clint.c
+++ b/drivers/clocksource/timer-clint.c
@@ -119,11 +119,21 @@ static int clint_clock_next_event(unsigned long delta,
 	return 0;
 }
 
+static int clint_clock_shutdown(struct clock_event_device *evt)
+{
+	void __iomem *r = clint_timer_cmp +
+			  cpuid_to_hartid_map(smp_processor_id());
+
+	writeq_relaxed(ULONG_MAX, 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,
+	.name				= "clint_clockevent",
+	.features			= CLOCK_EVT_FEAT_ONESHOT,
+	.rating				= 100,
+	.set_next_event			= clint_clock_next_event,
+	.set_state_shutdown		= clint_clock_shutdown,
 };
 
 static int clint_timer_starting_cpu(unsigned int cpu)
-- 
2.43.0


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Re: [PATCH 2/3] clocksource/drivers/timer-clint: Add set_state_shutdown

[Samuel Holland]

Hi Jisheng,

On 2024-03-27 10:35 AM, Jisheng Zhang wrote:
> Add clocksource detach/shutdown callback to disable RISC-V timer interrupt when
> switching out clockevent from clint timer to another timer.
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  drivers/clocksource/timer-clint.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c
> index 09fd292eb83d..56cf6c672e6d 100644
> --- a/drivers/clocksource/timer-clint.c
> +++ b/drivers/clocksource/timer-clint.c
> @@ -119,11 +119,21 @@ static int clint_clock_next_event(unsigned long delta,
>  	return 0;
>  }
>  
> +static int clint_clock_shutdown(struct clock_event_device *evt)
> +{
> +	void __iomem *r = clint_timer_cmp +
> +			  cpuid_to_hartid_map(smp_processor_id());
> +
> +	writeq_relaxed(ULONG_MAX, r);

This needs to be ULLONG_MAX to produce a 64-bit value on riscv32.

Regards,
Samuel

> +	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,
> +	.name				= "clint_clockevent",
> +	.features			= CLOCK_EVT_FEAT_ONESHOT,
> +	.rating				= 100,
> +	.set_next_event			= clint_clock_next_event,
> +	.set_state_shutdown		= clint_clock_shutdown,
>  };
>  
>  static int clint_timer_starting_cpu(unsigned int cpu)


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[PATCH 3/3] clocksource/drivers/timer-clint: Add set_state_oneshot_stopped

[Jisheng Zhang]

To avoid spurious timer interrupts when KTIME_MAX is used, we need to
configure set_state_oneshot_stopped(). Although implementing this is
optional, it still affects things like power management for the extra
timer interrupt.

Check commit 8fff52fd5093 ("clockevents: Introduce
CLOCK_EVT_STATE_ONESHOT_STOPPED state") for more information.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 drivers/clocksource/timer-clint.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c
index 56cf6c672e6d..f5c04520d6b1 100644
--- a/drivers/clocksource/timer-clint.c
+++ b/drivers/clocksource/timer-clint.c
@@ -134,6 +134,7 @@ static DEFINE_PER_CPU(struct clock_event_device, clint_clock_event) = {
 	.rating				= 100,
 	.set_next_event			= clint_clock_next_event,
 	.set_state_shutdown		= clint_clock_shutdown,
+	.set_state_oneshot_stopped	= clint_clock_shutdown,
 };
 
 static int clint_timer_starting_cpu(unsigned int cpu)
-- 
2.43.0


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