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| author | Kent Gibson <warthog618@gmail.com> | 2020-10-15 01:11:56 +0200 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2020-12-05 23:22:47 +0100 |
| commit | 26d060e47e25f2c715a1b2c48fea391f67907a30 (patch) | |
| tree | 084ae8859583599fbf3f8ee1c7f9a472dc5eaaf2 /include | |
| parent | gpio: msc313: MStar MSC313 GPIO driver (diff) | |
| download | linux-26d060e47e25f2c715a1b2c48fea391f67907a30.tar.xz linux-26d060e47e25f2c715a1b2c48fea391f67907a30.zip | |
gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
Using CLOCK_REALTIME as the source for event timestamps is crucial for
some specific applications, particularly those requiring timetamps
relative to a PTP clock, so provide an option to switch the event
timestamp source from the default CLOCK_MONOTONIC to CLOCK_REALTIME.
Note that CLOCK_REALTIME was the default source clock for GPIO until
Linux 5.7 when it was changed to CLOCK_MONOTONIC due to issues with the
shifting of the realtime clock.
Providing this option maintains the CLOCK_MONOTONIC as the default,
while also providing a path forward for those dependent on the pre-5.7
behaviour.
Suggested-by: Jack Winch <sunt.un.morcov@gmail.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20201014231158.34117-2-warthog618@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/linux/gpio.h | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h index 2072c260f5d0..e4eb0b8c5cf9 100644 --- a/include/uapi/linux/gpio.h +++ b/include/uapi/linux/gpio.h @@ -65,6 +65,7 @@ struct gpiochip_info { * @GPIO_V2_LINE_FLAG_BIAS_PULL_UP: line has pull-up bias enabled * @GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN: line has pull-down bias enabled * @GPIO_V2_LINE_FLAG_BIAS_DISABLED: line has bias disabled + * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME: line events contain REALTIME timestamps */ enum gpio_v2_line_flag { GPIO_V2_LINE_FLAG_USED = _BITULL(0), @@ -78,6 +79,7 @@ enum gpio_v2_line_flag { GPIO_V2_LINE_FLAG_BIAS_PULL_UP = _BITULL(8), GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN = _BITULL(9), GPIO_V2_LINE_FLAG_BIAS_DISABLED = _BITULL(10), + GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME = _BITULL(11), }; /** @@ -270,9 +272,6 @@ enum gpio_v2_line_event_id { /** * struct gpio_v2_line_event - The actual event being pushed to userspace * @timestamp_ns: best estimate of time of event occurrence, in nanoseconds. - * The @timestamp_ns is read from %CLOCK_MONOTONIC and is intended to allow - * the accurate measurement of the time between events. It does not provide - * the wall-clock time. * @id: event identifier with value from &enum gpio_v2_line_event_id * @offset: the offset of the line that triggered the event * @seqno: the sequence number for this event in the sequence of events for @@ -280,6 +279,13 @@ enum gpio_v2_line_event_id { * @line_seqno: the sequence number for this event in the sequence of * events on this particular line * @padding: reserved for future use + * + * By default the @timestamp_ns is read from %CLOCK_MONOTONIC and is + * intended to allow the accurate measurement of the time between events. + * It does not provide the wall-clock time. + * + * If the %GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME flag is set then the + * @timestamp_ns is read from %CLOCK_REALTIME. */ struct gpio_v2_line_event { __aligned_u64 timestamp_ns; |