From: Brian Norris <briannorris@xxxxxxxxxxxx>
The 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@xxxxxxxxxxxx>
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
---
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 ef5fbe9..ad440a2 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 73c487d..a2503db 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);
--
2.7.4
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