Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 194444c5 authored by Marc Gonzalez's avatar Marc Gonzalez Committed by Russell King
Browse files

ARM: 8441/2: twd: Don't set CLOCK_EVT_FEAT_C3STOP unconditionally 



In 5388a6b2 ("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: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarMarc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent ff5138f3

Documentation/devicetree/bindings/arm/twd.txt

+5 −0
Original line number Diff line number Diff line
@@ -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 {

arch/arm/kernel/smp_twd.c

+4 −1
Original line number Diff line number Diff line
@@ -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