linux-kernel - [PATCH 4.9 067/152] clocksource/drivers/arm_arch

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Date:   Mon, 10 Apr 2017 18:41:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 067/152] clocksource/drivers/arm_arch_timer: Dont assume clock runs in suspend

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Brian Norris <briannorris@...omium.org>

[ Upstream commit d8ec7595a013237f82d965dcf981571aeb41855b ]

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@...omium.org>
Reviewed-by: Douglas Anderson <dianders@...omium.org>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 Documentation/devicetree/bindings/arm/arch_timer.txt |    5 +++++
 drivers/clocksource/arm_arch_timer.c                 |    9 ++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

--- 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:
 
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -81,6 +81,7 @@ static struct clock_event_device __percp
 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_co
 	.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
 		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(str
 	    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);