[PATCH v2 1/2] clocksource: arm_arch_timer: Don't assume clock runs in suspend

[PATCH v2 1/2] clocksource: arm_arch_timer: Don't assume clock runs in suspend

[Brian Norris]

The ARM ARM specifies that the system counter "must be implemented in an
always-on power domain," and so we try to use the counter as a source of
timekeeping across suspend/resume. Unfortunately, some SoCs (e.g.,
Rockchip's RK3399) do not keep the counter ticking properly when
switched from their high-power clock to the lower-power clock used in
system suspend. Support this quirk by adding a new device tree property.

Signed-off-by: Brian Norris <briannorris@chromium.org>
---
v2:
 * add new device tree property, instead of re-using the "always-on"
   property (which has different meaning)

 Documentation/devicetree/bindings/arm/arch_timer.txt | 5 +++++
 drivers/clocksource/arm_arch_timer.c                 | 9 ++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/arm/arch_timer.txt b/Documentation/devicetree/bindings/arm/arch_timer.txt
index ef5fbe9a77c7..ad440a2b8051 100644
--- a/Documentation/devicetree/bindings/arm/arch_timer.txt
+++ b/Documentation/devicetree/bindings/arm/arch_timer.txt
@@ -38,6 +38,11 @@ to deliver its interrupts via SPIs.
   architecturally-defined reset values. Only supported for 32-bit
   systems which follow the ARMv7 architected reset values.
 
+- arm,no-tick-in-suspend : The main counter does not tick when the system is in
+  low-power system suspend on some SoCs. This behavior does not match the
+  Architecture Reference Manual's specification that the system counter "must
+  be implemented in an always-on power domain."
+
 
 Example:
 
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 73c487da6d2a..a2503db7e533 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -81,6 +81,7 @@ static struct clock_event_device __percpu *arch_timer_evt;
 static enum ppi_nr arch_timer_uses_ppi = VIRT_PPI;
 static bool arch_timer_c3stop;
 static bool arch_timer_mem_use_virtual;
+static bool arch_counter_suspend_stop;
 
 static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
 
@@ -576,7 +577,7 @@ static struct clocksource clocksource_counter = {
 	.rating	= 400,
 	.read	= arch_counter_read,
 	.mask	= CLOCKSOURCE_MASK(56),
-	.flags	= CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP,
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
 static struct cyclecounter cyclecounter = {
@@ -616,6 +617,8 @@ static void __init arch_counter_register(unsigned type)
 		arch_timer_read_counter = arch_counter_get_cntvct_mem;
 	}
 
+	if (!arch_counter_suspend_stop)
+		clocksource_counter.flags |= CLOCK_SOURCE_SUSPEND_NONSTOP;
 	start_count = arch_timer_read_counter();
 	clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 	cyclecounter.mult = clocksource_counter.mult;
@@ -907,6 +910,10 @@ static int __init arch_timer_of_init(struct device_node *np)
 	    of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
 		arch_timer_uses_ppi = PHYS_SECURE_PPI;
 
+	/* On some systems, the counter stops ticking when in suspend. */
+	arch_counter_suspend_stop = of_property_read_bool(np,
+							 "arm,no-tick-in-suspend");
+
 	return arch_timer_init();
 }
 CLOCKSOURCE_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_of_init);
-- 
2.8.0.rc3.226.g39d4020

[PATCH v2 2/2] arm64: dts: rockchip: arch counter doesn't tick in system suspend

[Brian Norris]

The "arm,no-tick-in-suspend" property was introduced to note
implementations where the system counter does not quite follow the ARM
specification that it "must be implemented in an always-on power
domain".

Particularly, RK3399's counter stops ticking when we switch from the
24MHz clock to the 32KHz clock in low-power suspend, so let's mark it as
such.

Signed-off-by: Brian Norris <briannorris@chromium.org>
---
v2: new in v2

 arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index 76b28649f0b0..401c8be8c8ac 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -174,6 +174,7 @@
 			     <GIC_PPI 14 IRQ_TYPE_LEVEL_LOW 0>,
 			     <GIC_PPI 11 IRQ_TYPE_LEVEL_LOW 0>,
 			     <GIC_PPI 10 IRQ_TYPE_LEVEL_LOW 0>;
+		arm,no-tick-in-suspend;
 	};
 
 	xin24m: xin24m {
-- 
2.8.0.rc3.226.g39d4020

[PATCH v2 1/2] clocksource: arm_arch_timer: Don't assume clock runs in suspend

[Doug Anderson]

Hi,

On Tue, Oct 4, 2016 at 11:12 AM, Brian Norris <briannorris@chromium.org> wrote:
> The ARM ARM specifies that the system counter "must be implemented in an
> always-on power domain," and so we try to use the counter as a source of
> timekeeping across suspend/resume. Unfortunately, some SoCs (e.g.,
> Rockchip's RK3399) do not keep the counter ticking properly when
> switched from their high-power clock to the lower-power clock used in
> system suspend. Support this quirk by adding a new device tree property.
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v2:
>  * add new device tree property, instead of re-using the "always-on"
>    property (which has different meaning)
>
>  Documentation/devicetree/bindings/arm/arch_timer.txt | 5 +++++
>  drivers/clocksource/arm_arch_timer.c                 | 9 ++++++++-
>  2 files changed, 13 insertions(+), 1 deletion(-)

FWIW:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

[PATCH v2 2/2] arm64: dts: rockchip: arch counter doesn't tick in system suspend

[Doug Anderson]

Hi,

On Tue, Oct 4, 2016 at 11:12 AM, Brian Norris <briannorris@chromium.org> wrote:
> The "arm,no-tick-in-suspend" property was introduced to note
> implementations where the system counter does not quite follow the ARM
> specification that it "must be implemented in an always-on power
> domain".
>
> Particularly, RK3399's counter stops ticking when we switch from the
> 24MHz clock to the 32KHz clock in low-power suspend, so let's mark it as
> such.
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v2: new in v2
>
>  arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Douglas Anderson <dianders@chromium.org>

[PATCH v2 1/2] clocksource: arm_arch_timer: Don't assume clock runs in suspend

[Marc Zyngier]

On Tue,  4 Oct 2016 11:12:09 -0700
Brian Norris <briannorris@chromium.org> wrote:

> The ARM ARM specifies that the system counter "must be implemented in an
> always-on power domain," and so we try to use the counter as a source of
> timekeeping across suspend/resume. Unfortunately, some SoCs (e.g.,
> Rockchip's RK3399) do not keep the counter ticking properly when
> switched from their high-power clock to the lower-power clock used in
> system suspend. Support this quirk by adding a new device tree property.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny.

[PATCH v2 1/2] clocksource: arm_arch_timer: Don't assume clock runs in suspend

[Daniel Lezcano]

On 04/10/2016 20:12, Brian Norris wrote:
> The ARM ARM specifies that the system counter "must be implemented in an
> always-on power domain," and so we try to use the counter as a source of
> timekeeping across suspend/resume. Unfortunately, some SoCs (e.g.,
> Rockchip's RK3399) do not keep the counter ticking properly when
> switched from their high-power clock to the lower-power clock used in
> system suspend. Support this quirk by adding a new device tree property.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---

Both patches applied for 4.10.

Thanks !

  -- Daniel

-- 
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