On Sun, 22 Sep 2019 10:50:12 -0700 Gwendal Grignou <gwendal@xxxxxxxxxxxx> wrote: > To improve sensor timestamp precision, given EC and AP are in > different time domains, the AP needs to try to record the exact > moment an event was signalled to the AP by the EC as soon as > possible after it happens. > > First thing in the hard irq is the best place for this. > > Signed-off-by: Gwendal Grignou <gwendal@xxxxxxxxxxxx> If this is only going to be used in IIO paths, the there is a control to set which clock is used. This is really a legacy thing due to me once picking a silly default, but we may be causing confusion by having that control but it having no effect. Otherwise looks good to me. > --- > drivers/platform/chrome/cros_ec.c | 18 +++++++++++++++++- > drivers/platform/chrome/cros_ec_lpc.c | 2 ++ > include/linux/platform_data/cros_ec_proto.h | 15 +++++++++++++++ > 3 files changed, 34 insertions(+), 1 deletion(-) > > diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c > index fd77e6fa74c2..f49eb1d1e3cd 100644 > --- a/drivers/platform/chrome/cros_ec.c > +++ b/drivers/platform/chrome/cros_ec.c > @@ -31,6 +31,21 @@ static struct cros_ec_platform pd_p = { > .cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_PD_INDEX), > }; > > +s64 cros_ec_get_time_ns(void) > +{ > + return ktime_get_boottime_ns(); > +} > +EXPORT_SYMBOL(cros_ec_get_time_ns); > + > +static irqreturn_t ec_irq_handler(int irq, void *data) > +{ > + struct cros_ec_device *ec_dev = data; > + > + ec_dev->last_event_time = cros_ec_get_time_ns(); > + > + return IRQ_WAKE_THREAD; > +} > + > static irqreturn_t ec_irq_thread(int irq, void *data) > { > struct cros_ec_device *ec_dev = data; > @@ -132,7 +147,8 @@ int cros_ec_register(struct cros_ec_device *ec_dev) > } > > if (ec_dev->irq) { > - err = devm_request_threaded_irq(dev, ec_dev->irq, NULL, > + err = devm_request_threaded_irq( > + dev, ec_dev->irq, ec_irq_handler, > ec_irq_thread, IRQF_TRIGGER_LOW | IRQF_ONESHOT, > "chromeos-ec", ec_dev); > if (err) { > diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c > index 7d10d909435f..3c77496e164d 100644 > --- a/drivers/platform/chrome/cros_ec_lpc.c > +++ b/drivers/platform/chrome/cros_ec_lpc.c > @@ -313,6 +313,8 @@ static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data) > { > struct cros_ec_device *ec_dev = data; > > + ec_dev->last_event_time = cros_ec_get_time_ns(); > + > if (ec_dev->mkbp_event_supported && > cros_ec_get_next_event(ec_dev, NULL) > 0) > blocking_notifier_call_chain(&ec_dev->event_notifier, 0, > diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h > index e91e3fcb0348..ab12e28f2107 100644 > --- a/include/linux/platform_data/cros_ec_proto.h > +++ b/include/linux/platform_data/cros_ec_proto.h > @@ -121,6 +121,8 @@ struct cros_ec_command { > * @event_data: Raw payload transferred with the MKBP event. > * @event_size: Size in bytes of the event data. > * @host_event_wake_mask: Mask of host events that cause wake from suspend. > + * @last_event_time: exact time from the hard irq when we got notified of > + * a new event. > * @ec: The platform_device used by the mfd driver to interface with the > * main EC. > * @pd: The platform_device used by the mfd driver to interface with the > @@ -161,6 +163,7 @@ struct cros_ec_device { > int event_size; > u32 host_event_wake_mask; > u32 last_resume_result; > + s64 last_event_time; > > /* The platform devices used by the mfd driver */ > struct platform_device *ec; > @@ -308,4 +311,16 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev, bool *wake_event); > */ > u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev); > > +/** > + * cros_ec_get_time_ns - Return time in ns. > + * > + * This is the function used to record the time for last_event_time in struct > + * cros_ec_device during the hard irq. > + * > + * This function is probably implemented using ktime_get_boot_ns(), but it's > + * exposed here to make sure all cros_ec drivers use the same code path to get > + * the time. > + */ > +s64 cros_ec_get_time_ns(void); > + > #endif /* __LINUX_CROS_EC_PROTO_H */