Messages in this thread | | | Subject | Re: [RFC 08/11] gpiolib: cdev: Add hardware timestamp clock type | From | Jon Hunter <> | Date | Tue, 3 Aug 2021 17:42:37 +0100 |
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On 30/07/2021 03:33, Dipen Patel wrote: > > On 7/9/21 1:30 AM, Jon Hunter wrote: >> On 26/06/2021 00:55, Dipen Patel wrote: >>> This patch adds new clock type for the GPIO controller which can >>> timestamp gpio lines using hardware means. To expose such >>> functionalities to the userspace, code has been added in this patch >>> where during line create call, it checks for new clock type and if >>> requested, calls hardware timestamp related API from gpiolib.c. >>> During line change event, it retrieves timestamp in nano seconds by >>> calling gpiod_get_hw_timestamp API from gpiolib.c. At the line release, >>> it disables this functionality by calling gpiod_hw_timestamp_control. >>> >>> Signed-off-by: Dipen Patel <dipenp@nvidia.com> >>> --- >>> drivers/gpio/gpiolib-cdev.c | 65 +++++++++++++++++++++++++++++++++++-- >>> include/uapi/linux/gpio.h | 1 + >>> 2 files changed, 64 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c >>> index 1631727bf0da..9f98c727e937 100644 >>> --- a/drivers/gpio/gpiolib-cdev.c >>> +++ b/drivers/gpio/gpiolib-cdev.c >>> @@ -518,6 +518,7 @@ struct linereq { >>> GPIO_V2_LINE_DRIVE_FLAGS | \ >>> GPIO_V2_LINE_EDGE_FLAGS | \ >>> GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME | \ >>> + GPIO_V2_LINE_FLAG_EVENT_CLOCK_HARDWARE | \ >>> GPIO_V2_LINE_BIAS_FLAGS) >>> >>> static void linereq_put_event(struct linereq *lr, >>> @@ -540,9 +541,20 @@ static void linereq_put_event(struct linereq *lr, >>> >>> static u64 line_event_timestamp(struct line *line) >>> { >>> + bool block; >>> + >>> if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &line->desc->flags)) >>> return ktime_get_real_ns(); >>> >>> + if (test_bit(FLAG_EVENT_CLOCK_HARDWARE, &line->desc->flags)) { >>> + if (irq_count()) >>> + block = false; >>> + else >>> + block = true; >>> + >>> + return gpiod_get_hw_timestamp(line->desc, block); >>> + } >>> + >>> return ktime_get_ns(); >>> } >> >> Looking at line_event_timestamp() and the callers of this function, it >> appears that this should always return nanoseconds. Does >> gpiod_get_hw_timestamp() return nanoseconds? > Yes, it returns in ns to align with line_event_timestamp.
It might be worth updating the function name to gpiod_get_hw_timestamp_ns() so that this is clear.
Jon
-- nvpublic
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