sh: dyntick infrastructure.

This adds basic NO_IDLE_HZ support to the SH timer API so timers
are able to wire it up. Taken from the ARM version, as it fit in
to our API with very few changes needed.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 48308dc86e33..aa1ebc561b84 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -423,6 +423,24 @@ config SH_TIMER_IRQ
         default "140" if CPU_SUBTYPE_SH7206
         default "16"
 
+config NO_IDLE_HZ
+        bool "Dynamic tick timer"
+        help
+          Select this option if you want to disable continuous timer ticks
+          and have them programmed to occur as required. This option saves
+          power as the system can remain in idle state for longer.
+
+          By default dynamic tick is disabled during the boot, and can be
+          manually enabled with:
+
+            echo 1 > /sys/devices/system/timer/timer0/dyn_tick
+
+          Alternatively, if you want dynamic tick automatically enabled
+          during boot, pass "dyntick=enable" via the kernel command string.
+
+          Please note that dynamic tick may affect the accuracy of
+          timekeeping on some platforms depending on the implementation.
+
 config SH_PCLK_FREQ
         int "Peripheral clock frequency (in Hz)"
         default "27000000" if CPU_SUBTYPE_SH73180 || CPU_SUBTYPE_SH7343