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authorRich Felker <dalias@libc.org>2016-10-13 21:51:06 +0000
committerThomas Gleixner <tglx@linutronix.de>2016-10-20 20:10:17 +0200
commit9995f4f184613fb02ee73092b03545520a72b104 (patch)
treeacbfa2a174303da0fe1f0eb091e2f68872b32950 /drivers/clocksource/Kconfig
parenta2ce092be34c4951e23104a0bfdec08f9577fada (diff)
clocksource: Add J-Core timer/clocksource driver
At the hardware level, the J-Core PIT is integrated with the interrupt controller, but it is represented as its own device and has an independent programming interface. It provides a 12-bit countdown timer, which is not presently used, and a periodic timer. The interval length for the latter is programmable via a 32-bit throttle register whose units are determined by a bus-period register. The periodic timer is used to implement both periodic and oneshot clock event modes; in oneshot mode the interrupt handler simply disables the timer as soon as it fires. Despite its device tree node representing an interrupt for the PIT, the actual irq generated is programmable, not hard-wired. The driver is responsible for programming the PIT to generate the hardware irq number that the DT assigns to it. On SMP configurations, J-Core provides cpu-local instances of the PIT; no broadcast timer is needed. This driver supports the creation of the necessary per-cpu clock_event_device instances. A nanosecond-resolution clocksource is provided using the J-Core "RTC" registers, which give a 64-bit seconds count and 32-bit nanoseconds that wrap every second. The driver converts these to a full-range 32-bit nanoseconds count. Signed-off-by: Rich Felker <dalias@libc.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: devicetree@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Rob Herring <robh+dt@kernel.org> Link: http://lkml.kernel.org/r/b591ff12cc5ebf63d1edc98da26046f95a233814.1476393790.git.dalias@libc.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/clocksource/Kconfig')
-rw-r--r--drivers/clocksource/Kconfig10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 245190839359..e2c6e43cf8ca 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -417,6 +417,16 @@ config SYS_SUPPORTS_SH_TMU
config SYS_SUPPORTS_EM_STI
bool
+config CLKSRC_JCORE_PIT
+ bool "J-Core PIT timer driver" if COMPILE_TEST
+ depends on OF
+ depends on GENERIC_CLOCKEVENTS
+ depends on HAS_IOMEM
+ select CLKSRC_MMIO
+ help
+ This enables build of clocksource and clockevent driver for
+ the integrated PIT in the J-Core synthesizable, open source SoC.
+
config SH_TIMER_CMT
bool "Renesas CMT timer driver" if COMPILE_TEST
depends on GENERIC_CLOCKEVENTS