diff options
| -rw-r--r-- | drivers/clocksource/Kconfig | 15 | ||||
| -rw-r--r-- | drivers/clocksource/arm_arch_timer.c | 15 | ||||
| -rw-r--r-- | include/clocksource/arm_arch_timer.h | 2 |
3 files changed, 32 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index f151c6cf27c3..593485b02ee5 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -67,6 +67,21 @@ config ARM_ARCH_TIMER bool select CLKSRC_OF if OF +config ARM_ARCH_TIMER_EVTSTREAM + bool "Support for ARM architected timer event stream generation" + default y if ARM_ARCH_TIMER + help + This option enables support for event stream generation based on + the ARM architected timer. It is used for waking up CPUs executing + the wfe instruction at a frequency represented as a power-of-2 + divisor of the clock rate. + The main use of the event stream is wfe-based timeouts of userspace + locking implementations. It might also be useful for imposing timeout + on wfe to safeguard against any programming errors in case an expected + event is not generated. + This must be disabled for hardware validation purposes to detect any + hardware anomalies of missing events. + config CLKSRC_METAG_GENERIC def_bool y if METAG help diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 053d846ab5b1..d8f7eecce100 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -123,6 +123,19 @@ static int arch_timer_set_next_event_phys(unsigned long evt, return 0; } +static void arch_timer_configure_evtstream(void) +{ + int evt_stream_div, pos; + + /* Find the closest power of two to the divisor */ + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; + pos = fls(evt_stream_div); + if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) + pos--; + /* enable event stream */ + arch_timer_evtstrm_enable(min(pos, 15)); +} + static int __cpuinit arch_timer_setup(struct clock_event_device *clk) { clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; @@ -154,6 +167,8 @@ static int __cpuinit arch_timer_setup(struct clock_event_device *clk) } arch_counter_set_user_access(); + if (IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM)) + arch_timer_configure_evtstream(); return 0; } diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h index 551f7e918120..c4d0fc4855ab 100644 --- a/include/clocksource/arm_arch_timer.h +++ b/include/clocksource/arm_arch_timer.h @@ -37,6 +37,8 @@ #define ARCH_TIMER_USR_VT_ACCESS_EN (1 << 8) /* virtual timer registers */ #define ARCH_TIMER_USR_PT_ACCESS_EN (1 << 9) /* physical timer registers */ +#define ARCH_TIMER_EVT_STREAM_FREQ 10000 /* 100us */ + #ifdef CONFIG_ARM_ARCH_TIMER extern u32 arch_timer_get_rate(void); |