Le 11/01/2017 à 14:50, David Engraf a écrit : > On newer boards the TC can be read as single 32 bit value without locking. > Thus the clock can be used as reference for sched_clock which is much more > accurate than the jiffies implementation. > > Tested on a Atmel SAMA5D2 board. > > Signed-off-by: David Engraf <[email protected]>
Acked-by: Nicolas Ferre <[email protected]> Thanks, > --- > drivers/clocksource/tcb_clksrc.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/clocksource/tcb_clksrc.c > b/drivers/clocksource/tcb_clksrc.c > index d4ca996..745844e 100644 > --- a/drivers/clocksource/tcb_clksrc.c > +++ b/drivers/clocksource/tcb_clksrc.c > @@ -10,6 +10,7 @@ > #include <linux/io.h> > #include <linux/platform_device.h> > #include <linux/atmel_tc.h> > +#include <linux/sched_clock.h> > > > /* > @@ -56,11 +57,16 @@ static u64 tc_get_cycles(struct clocksource *cs) > return (upper << 16) | lower; > } > > -static u64 tc_get_cycles32(struct clocksource *cs) > +static u32 tc_get_cv32(void) > { > return __raw_readl(tcaddr + ATMEL_TC_REG(0, CV)); > } > > +static u64 tc_get_cycles32(struct clocksource *cs) > +{ > + return tc_get_cv32(); > +} > + > static struct clocksource clksrc = { > .name = "tcb_clksrc", > .rating = 200, > @@ -69,6 +75,11 @@ static struct clocksource clksrc = { > .flags = CLOCK_SOURCE_IS_CONTINUOUS, > }; > > +static u64 notrace tc_read_sched_clock(void) > +{ > + return tc_get_cv32(); > +} > + > #ifdef CONFIG_GENERIC_CLOCKEVENTS > > struct tc_clkevt_device { > @@ -339,6 +350,9 @@ static int __init tcb_clksrc_init(void) > clksrc.read = tc_get_cycles32; > /* setup ony channel 0 */ > tcb_setup_single_chan(tc, best_divisor_idx); > + > + /* register sched_clock on chips with single 32 bit counter */ > + sched_clock_register(tc_read_sched_clock, 32, divided_rate); > } else { > /* tclib will give us three clocks no matter what the > * underlying platform supports. > -- Nicolas Ferre
