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clocksource/drivers/arm_arch_timer: Don't assume clock runs in suspend

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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@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Brian Norris 2016-10-04 11:12:09 -07:00 committed by Daniel Lezcano
parent baa73d9e47
commit d8ec7595a0
2 changed files with 13 additions and 1 deletions
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5
Documentation/devicetree/bindings/arm/arch_timer.txt
View File

@ -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:

9
drivers/clocksource/arm_arch_timer.c
View File

@ -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);