* [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
@ 2020-10-14 6:27 Kent Gibson
2020-10-14 6:27 ` [PATCH 1/3] " Kent Gibson
` (3 more replies)
0 siblings, 4 replies; 6+ messages in thread
From: Kent Gibson @ 2020-10-14 6:27 UTC (permalink / raw)
To: linux-kernel, linux-gpio, bgolaszewski, linus.walleij; +Cc: Kent Gibson
This patch set adds the option to select CLOCK_REALTIME as the source
clock for line events.
The first patch is the core of the change, while the remaining two update
the GPIO tools to make use of the new option.
Kent Gibson (3):
gpiolib: cdev: allow edge event timestamps to be configured as
REALTIME
tools: gpio: add support for reporting realtime event clock to lsgpio
tools: gpio: add option to report wall-clock time to gpio-event-mon
drivers/gpio/gpiolib-cdev.c | 21 ++++++++++++++++++---
drivers/gpio/gpiolib.h | 1 +
include/uapi/linux/gpio.h | 12 +++++++++---
tools/gpio/gpio-event-mon.c | 6 +++++-
tools/gpio/lsgpio.c | 4 ++++
5 files changed, 37 insertions(+), 7 deletions(-)
--
2.28.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
2020-10-14 6:27 [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Kent Gibson
@ 2020-10-14 6:27 ` Kent Gibson
2020-10-14 16:17 ` Kent Gibson
2020-10-14 6:27 ` [PATCH 2/3] tools: gpio: add support for reporting realtime event clock to lsgpio Kent Gibson
` (2 subsequent siblings)
3 siblings, 1 reply; 6+ messages in thread
From: Kent Gibson @ 2020-10-14 6:27 UTC (permalink / raw)
To: linux-kernel, linux-gpio, bgolaszewski, linus.walleij
Cc: Kent Gibson, Jack Winch
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>
---
drivers/gpio/gpiolib-cdev.c | 21 ++++++++++++++++++---
drivers/gpio/gpiolib.h | 1 +
include/uapi/linux/gpio.h | 12 +++++++++---
3 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 678de9264617..147626a78a92 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -515,6 +515,7 @@ struct linereq {
GPIO_V2_LINE_DIRECTION_FLAGS | \
GPIO_V2_LINE_DRIVE_FLAGS | \
GPIO_V2_LINE_EDGE_FLAGS | \
+ GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME | \
GPIO_V2_LINE_BIAS_FLAGS)
static void linereq_put_event(struct linereq *lr,
@@ -535,6 +536,14 @@ static void linereq_put_event(struct linereq *lr,
pr_debug_ratelimited("event FIFO is full - event dropped\n");
}
+static unsigned long line_event_timestamp(struct line *line)
+{
+ if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &line->desc->flags))
+ return ktime_get_real_ns();
+
+ return ktime_get_ns();
+
+}
static irqreturn_t edge_irq_thread(int irq, void *p)
{
struct line *line = p;
@@ -553,7 +562,7 @@ static irqreturn_t edge_irq_thread(int irq, void *p)
* which case we didn't get the timestamp from
* edge_irq_handler().
*/
- le.timestamp_ns = ktime_get_ns();
+ le.timestamp_ns = line_event_timestamp(line);
if (lr->num_lines != 1)
line->req_seqno = atomic_inc_return(&lr->seqno);
}
@@ -598,7 +607,7 @@ static irqreturn_t edge_irq_handler(int irq, void *p)
* Just store the timestamp in hardirq context so we get it as
* close in time as possible to the actual event.
*/
- line->timestamp_ns = ktime_get_ns();
+ line->timestamp_ns = line_event_timestamp(line);
if (lr->num_lines != 1)
line->req_seqno = atomic_inc_return(&lr->seqno);
@@ -673,7 +682,7 @@ static void debounce_work_func(struct work_struct *work)
memset(&le, 0, sizeof(le));
lr = line->req;
- le.timestamp_ns = ktime_get_ns();
+ le.timestamp_ns = line_event_timestamp(line);
le.offset = gpio_chip_hwgpio(line->desc);
line->line_seqno++;
le.line_seqno = line->line_seqno;
@@ -977,6 +986,9 @@ static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
assign_bit(FLAG_BIAS_DISABLE, flagsp,
flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
+
+ assign_bit(FLAG_EVENT_CLOCK_REALTIME, flagsp,
+ flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME);
}
static long linereq_get_values(struct linereq *lr, void __user *ip)
@@ -1940,6 +1952,9 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
if (test_bit(FLAG_EDGE_FALLING, &desc->flags))
info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
+ if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &desc->flags))
+ info->flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
+
debounce_period_us = READ_ONCE(desc->debounce_period_us);
if (debounce_period_us) {
info->attrs[num_attrs].id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index b674b5bb980e..2f228ffe8320 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -116,6 +116,7 @@ struct gpio_desc {
#define FLAG_BIAS_DISABLE 15 /* GPIO has pull disabled */
#define FLAG_EDGE_RISING 16 /* GPIO CDEV detects rising edge events */
#define FLAG_EDGE_FALLING 17 /* GPIO CDEV detects falling edge events */
+#define FLAG_EVENT_CLOCK_REALTIME 18 /* GPIO CDEV reports REALTIME timestamps in events */
/* Connection label */
const char *label;
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;
--
2.28.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/3] tools: gpio: add support for reporting realtime event clock to lsgpio
2020-10-14 6:27 [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Kent Gibson
2020-10-14 6:27 ` [PATCH 1/3] " Kent Gibson
@ 2020-10-14 6:27 ` Kent Gibson
2020-10-14 6:27 ` [PATCH 3/3] tools: gpio: add option to report wall-clock time to gpio-event-mon Kent Gibson
2020-10-14 7:59 ` [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Bartosz Golaszewski
3 siblings, 0 replies; 6+ messages in thread
From: Kent Gibson @ 2020-10-14 6:27 UTC (permalink / raw)
To: linux-kernel, linux-gpio, bgolaszewski, linus.walleij; +Cc: Kent Gibson
Add support for reporting if a line is configured to report realtime
timestamps in events.
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
tools/gpio/lsgpio.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c
index 5a05a454d0c9..c61d061247e1 100644
--- a/tools/gpio/lsgpio.c
+++ b/tools/gpio/lsgpio.c
@@ -65,6 +65,10 @@ struct gpio_flag flagnames[] = {
.name = "bias-disabled",
.mask = GPIO_V2_LINE_FLAG_BIAS_DISABLED,
},
+ {
+ .name = "clock-realtime",
+ .mask = GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME,
+ },
};
static void print_attributes(struct gpio_v2_line_info *info)
--
2.28.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 3/3] tools: gpio: add option to report wall-clock time to gpio-event-mon
2020-10-14 6:27 [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Kent Gibson
2020-10-14 6:27 ` [PATCH 1/3] " Kent Gibson
2020-10-14 6:27 ` [PATCH 2/3] tools: gpio: add support for reporting realtime event clock to lsgpio Kent Gibson
@ 2020-10-14 6:27 ` Kent Gibson
2020-10-14 7:59 ` [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Bartosz Golaszewski
3 siblings, 0 replies; 6+ messages in thread
From: Kent Gibson @ 2020-10-14 6:27 UTC (permalink / raw)
To: linux-kernel, linux-gpio, bgolaszewski, linus.walleij; +Cc: Kent Gibson
Add support for selecting the realtime clock for events.
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
tools/gpio/gpio-event-mon.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/tools/gpio/gpio-event-mon.c b/tools/gpio/gpio-event-mon.c
index 90c3155f05b1..cacd66ad7926 100644
--- a/tools/gpio/gpio-event-mon.c
+++ b/tools/gpio/gpio-event-mon.c
@@ -148,6 +148,7 @@ void print_usage(void)
" -s Set line as open source\n"
" -r Listen for rising edges\n"
" -f Listen for falling edges\n"
+ " -w Report the wall-clock time for events\n"
" -b <n> Debounce the line with period n microseconds\n"
" [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
" -? This helptext\n"
@@ -173,7 +174,7 @@ int main(int argc, char **argv)
memset(&config, 0, sizeof(config));
config.flags = GPIO_V2_LINE_FLAG_INPUT;
- while ((c = getopt(argc, argv, "c:n:o:b:dsrf?")) != -1) {
+ while ((c = getopt(argc, argv, "c:n:o:b:dsrfw?")) != -1) {
switch (c) {
case 'c':
loops = strtoul(optarg, NULL, 10);
@@ -204,6 +205,9 @@ int main(int argc, char **argv)
case 'f':
config.flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
break;
+ case 'w':
+ config.flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
+ break;
case '?':
print_usage();
return -1;
--
2.28.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
2020-10-14 6:27 [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Kent Gibson
` (2 preceding siblings ...)
2020-10-14 6:27 ` [PATCH 3/3] tools: gpio: add option to report wall-clock time to gpio-event-mon Kent Gibson
@ 2020-10-14 7:59 ` Bartosz Golaszewski
3 siblings, 0 replies; 6+ messages in thread
From: Bartosz Golaszewski @ 2020-10-14 7:59 UTC (permalink / raw)
To: Kent Gibson; +Cc: LKML, linux-gpio, Linus Walleij
On Wed, Oct 14, 2020 at 8:28 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> This patch set adds the option to select CLOCK_REALTIME as the source
> clock for line events.
>
> The first patch is the core of the change, while the remaining two update
> the GPIO tools to make use of the new option.
>
> Kent Gibson (3):
> gpiolib: cdev: allow edge event timestamps to be configured as
> REALTIME
> tools: gpio: add support for reporting realtime event clock to lsgpio
> tools: gpio: add option to report wall-clock time to gpio-event-mon
>
> drivers/gpio/gpiolib-cdev.c | 21 ++++++++++++++++++---
> drivers/gpio/gpiolib.h | 1 +
> include/uapi/linux/gpio.h | 12 +++++++++---
> tools/gpio/gpio-event-mon.c | 6 +++++-
> tools/gpio/lsgpio.c | 4 ++++
> 5 files changed, 37 insertions(+), 7 deletions(-)
>
> --
> 2.28.0
>
The entire series looks good to me.
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Linus: do you think this can still make it into v5.10 as an
improvement to the new uAPI or do we have to wait until the next merge
window? Will you send another PR in this cycle?
Bartosz
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
2020-10-14 6:27 ` [PATCH 1/3] " Kent Gibson
@ 2020-10-14 16:17 ` Kent Gibson
0 siblings, 0 replies; 6+ messages in thread
From: Kent Gibson @ 2020-10-14 16:17 UTC (permalink / raw)
To: linux-kernel, linux-gpio, bgolaszewski, linus.walleij; +Cc: Jack Winch
On Wed, Oct 14, 2020 at 02:27:38PM +0800, Kent Gibson wrote:
> 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.
>
[snip]
>
> static void linereq_put_event(struct linereq *lr,
> @@ -535,6 +536,14 @@ static void linereq_put_event(struct linereq *lr,
> pr_debug_ratelimited("event FIFO is full - event dropped\n");
> }
>
> +static unsigned long line_event_timestamp(struct line *line)
> +{
> + if (test_bit(FLAG_EVENT_CLOCK_REALTIME, &line->desc->flags))
> + return ktime_get_real_ns();
> +
> + return ktime_get_ns();
> +
> +}
One minor hitch - that should be returning u64, not unsigned long,
or the time gets reduced to 32bit on 32bit platforms.
It's getting late though, so I'll send out an update tomorrow.
Cheers,
Kent.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-10-14 16:17 UTC | newest]
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2020-10-14 6:27 [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Kent Gibson
2020-10-14 6:27 ` [PATCH 1/3] " Kent Gibson
2020-10-14 16:17 ` Kent Gibson
2020-10-14 6:27 ` [PATCH 2/3] tools: gpio: add support for reporting realtime event clock to lsgpio Kent Gibson
2020-10-14 6:27 ` [PATCH 3/3] tools: gpio: add option to report wall-clock time to gpio-event-mon Kent Gibson
2020-10-14 7:59 ` [PATCH 0/3] gpiolib: cdev: allow edge event timestamps to be configured as REALTIME Bartosz Golaszewski
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