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

[ 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@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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 8 insertions, 1 deletions

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);