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| author | Marc Gonzalez <marc_gonzalez@sigmadesigns.com> | 2015-10-09 09:20:47 (GMT) |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-10-09 15:22:53 (GMT) |
| commit | 194444c52edd857210b3895e83ce45c64b58e251 (patch) | |
| tree | 65e0cc031ef48d29ab39561728c75df51ef1959f | |
| parent | ff5138f3af4ed61ed42e00d7d771a0502460488f (diff) | |
| download | linux-194444c52edd857210b3895e83ce45c64b58e251.tar.xz | |
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 <mark.rutland@arm.com>
Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | Documentation/devicetree/bindings/arm/twd.txt | 5 | ||||
| -rw-r--r-- | arch/arm/kernel/smp_twd.c | 5 |
2 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/arm/twd.txt b/Documentation/devicetree/bindings/arm/twd.txt index 75b8610..383ea19 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 662ed88..4c1aa61 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 |