From 194444c52edd857210b3895e83ce45c64b58e251 Mon Sep 17 00:00:00 2001 From: Marc Gonzalez Date: Fri, 9 Oct 2015 10:20:47 +0100 Subject: [PATCH] ARM: 8441/2: twd: Don't set CLOCK_EVT_FEAT_C3STOP unconditionally In 5388a6b266 ("ARM: SMP: Always enable clock event broadcast support") Russell noted that "the TWD local timers are unable to wake up the CPU when it is placed into a low power mode". However, some platforms do not stop the TWD block in low-power mode, and can thus use the TWD timer in one-shot mode, without setting up a broadcast device. Make the driver check for the "always-on" boolean property, and set the CLOCK_EVT_FEAT_C3STOP flag accordingly. Acked-by: Mark Rutland Signed-off-by: Marc Gonzalez Signed-off-by: Russell King --- Documentation/devicetree/bindings/arm/twd.txt | 5 +++++ arch/arm/kernel/smp_twd.c | 5 ++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/arm/twd.txt b/Documentation/devicetree/bindings/arm/twd.txt index 75b8610939fa..383ea19c2bf0 100644 --- a/Documentation/devicetree/bindings/arm/twd.txt +++ b/Documentation/devicetree/bindings/arm/twd.txt @@ -19,6 +19,11 @@ interrupts. - reg : Specify the base address and the size of the TWD timer register window. +Optional + +- always-on : a boolean property. If present, the timer is powered through + an always-on power domain, therefore it never loses context. + Example: twd-timer@2c000600 { diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index 662ed88bc1f9..4c1aa61149bb 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -33,6 +33,7 @@ static unsigned long twd_timer_rate; static DEFINE_PER_CPU(bool, percpu_setup_called); static struct clock_event_device __percpu *twd_evt; +static int feat_c3stop; static int twd_ppi; static int twd_shutdown(struct clock_event_device *clk) @@ -294,7 +295,7 @@ static void twd_timer_setup(void) clk->name = "local_timer"; clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | - CLOCK_EVT_FEAT_C3STOP; + feat_c3stop; clk->rating = 350; clk->set_state_shutdown = twd_shutdown; clk->set_state_periodic = twd_set_periodic; @@ -349,6 +350,8 @@ static int __init twd_local_timer_common_register(struct device_node *np) goto out_irq; twd_get_clock(np); + if (!of_property_read_bool(np, "always-on")) + feat_c3stop = CLOCK_EVT_FEAT_C3STOP; /* * Immediately configure the timer on the boot CPU, unless we need -- 2.39.5