Some user space applications need to read some clocks.
Each read requires moving from user space to kernel space.
This asymmetry causes the measured offset to have a significant error.
Introduce a new ioctl, which can be used to measure the offset between
multiple clocks, from variety of types: PHC, virtual PHC and system time
(CLOCK_REALTIME). The offset includes the total time that the driver needs
to read the clock timestamp. Similar to the capability already introduced
by PTP_SYS_OFFSET ioctl (read PHC and system clock), with flexibility
regard clock types and number of required clocks.
New ioctl allows the reading of a list of clocks - up to PTP_MAX_CLOCKS.
Supported clocks IDs: PHC, virtual PHC and system time (CLOCK_REALTIME).
Up to PTP_MAX_SAMPLES times (per clock) in a single ioctl read.
The ioctl returns n_clocks timestamps for each measurement:
- clock 0 timestamp or system time
- ...
- clock n timestamp or system time
Signed-off-by: Sagi Maimon <[email protected]>
---
drivers/ptp/ptp_chardev.c | 38 +++++++++++++++++++++++++++++++++-
include/linux/posix-clock.h | 10 +++++++++
include/uapi/linux/ptp_clock.h | 13 ++++++++++++
kernel/time/posix-clock.c | 6 ++++++
4 files changed, 66 insertions(+), 1 deletion(-)
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 3f7a74788802..c5318f7c1f75 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -170,7 +170,9 @@ long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
struct ptp_clock_request req;
struct ptp_clock_caps caps;
struct ptp_clock_time *pct;
- unsigned int i, pin_index;
+ struct ptp_multi_clock_get *multi_clk_get = NULL;
+
+ unsigned int i, pin_index, j;
struct ptp_pin_desc pd;
struct timespec64 ts;
int enable, err = 0;
@@ -491,6 +493,40 @@ long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
set_bit(i, tsevq->mask);
break;
+ case PTP_MULTI_CLOCK_GET:
+ multi_clk_get = memdup_user((void __user *)arg, sizeof(*multi_clk_get));
+ if (IS_ERR(multi_clk_get)) {
+ err = PTR_ERR(multi_clk_get);
+ multi_clk_get = NULL;
+ break;
+ }
+ if (multi_clk_get->n_samples > PTP_MAX_SAMPLES) {
+ err = -EINVAL;
+ break;
+ }
+ if (multi_clk_get->n_clocks > PTP_MAX_CLOCKS) {
+ err = -EINVAL;
+ break;
+ }
+ for (j = 0; j < multi_clk_get->n_samples; j++) {
+ for (i = 0; i < multi_clk_get->n_clocks; i++) {
+ if (multi_clk_get->clkid_arr[i] == CLOCK_REALTIME) {
+ ktime_get_real_ts64(&ts);
+ } else {
+ err = pc_clock_gettime_wrapper(multi_clk_get->clkid_arr[i],
+ &ts);
+ if (err)
+ goto out;
+ }
+ multi_clk_get->ts[j][i].sec = ts.tv_sec;
+ multi_clk_get->ts[j][i].nsec = ts.tv_nsec;
+ }
+ }
+ if (copy_to_user((void __user *)arg, multi_clk_get,
+ sizeof(*multi_clk_get)))
+ err = -EFAULT;
+
+ break;
default:
err = -ENOTTY;
break;
diff --git a/include/linux/posix-clock.h b/include/linux/posix-clock.h
index ef8619f48920..dd88e8d8a66c 100644
--- a/include/linux/posix-clock.h
+++ b/include/linux/posix-clock.h
@@ -135,4 +135,14 @@ int posix_clock_register(struct posix_clock *clk, struct device *dev);
*/
void posix_clock_unregister(struct posix_clock *clk);
+/**
+ * pc_clock_gettime_warrper() - retrieve time of a clock specified by clock ID
+ * @id: Clock ID.
+ * @ts: clock time stamp.
+ *
+ * Returns the current time of a clock specified by clock ID, errno in case of
+ * error
+ */
+int pc_clock_gettime_wrapper(clockid_t id, struct timespec64 *ts);
+
#endif
diff --git a/include/uapi/linux/ptp_clock.h b/include/uapi/linux/ptp_clock.h
index da700999cad4..ef21cc97e9bf 100644
--- a/include/uapi/linux/ptp_clock.h
+++ b/include/uapi/linux/ptp_clock.h
@@ -165,6 +165,18 @@ struct ptp_sys_offset_precise {
unsigned int rsv[4]; /* Reserved for future use. */
};
+#define PTP_MAX_CLOCKS 20 /* Maximum number of clocks */
+
+struct ptp_multi_clock_get {
+ unsigned int n_clocks; /* Desired number of clocks. */
+ unsigned int n_samples; /* Desired number of measurements per clock. */
+ clockid_t clkid_arr[PTP_MAX_CLOCKS]; /* list of clock IDs */
+ /*
+ * Array of list of n_clocks clocks time samples n_samples times.
+ */
+ struct ptp_clock_time ts[PTP_MAX_SAMPLES][PTP_MAX_CLOCKS];
+};
+
enum ptp_pin_function {
PTP_PF_NONE,
PTP_PF_EXTTS,
@@ -226,6 +238,7 @@ struct ptp_pin_desc {
_IOWR(PTP_CLK_MAGIC, 18, struct ptp_sys_offset_extended)
#define PTP_MASK_CLEAR_ALL _IO(PTP_CLK_MAGIC, 19)
#define PTP_MASK_EN_SINGLE _IOW(PTP_CLK_MAGIC, 20, unsigned int)
+#define PTP_MULTI_CLOCK_GET _IOWR(PTP_CLK_MAGIC, 21, struct ptp_multi_clock_get)
struct ptp_extts_event {
struct ptp_clock_time t; /* Time event occured. */
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index 9de66bbbb3d1..8df0ba79ebc2 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -284,6 +284,12 @@ static int pc_clock_gettime(clockid_t id, struct timespec64 *ts)
return err;
}
+int pc_clock_gettime_wrapper(clockid_t id, struct timespec64 *ts)
+{
+ return pc_clock_gettime(id, ts);
+}
+EXPORT_SYMBOL_GPL(pc_clock_gettime_wrapper);
+
static int pc_clock_getres(clockid_t id, struct timespec64 *ts)
{
struct posix_clock_desc cd;
--
2.26.3
On Wed, Nov 22, 2023 at 09:43:52AM +0200, Sagi Maimon wrote:
> @@ -226,6 +238,7 @@ struct ptp_pin_desc {
> _IOWR(PTP_CLK_MAGIC, 18, struct ptp_sys_offset_extended)
> #define PTP_MASK_CLEAR_ALL _IO(PTP_CLK_MAGIC, 19)
> #define PTP_MASK_EN_SINGLE _IOW(PTP_CLK_MAGIC, 20, unsigned int)
> +#define PTP_MULTI_CLOCK_GET _IOWR(PTP_CLK_MAGIC, 21, struct ptp_multi_clock_get)
I like the idea, but let's have it as a new system call.
The system call will accept a list of clockid_t.
That would allow getting CLOCK_MONOTONIC and PHC time stamps, for example.
Thanks,
Richard
On Wed, 22 Nov 2023 09:43:52 +0200 Sagi Maimon wrote:
> Some user space applications need to read some clocks.
> Each read requires moving from user space to kernel space.
> This asymmetry causes the measured offset to have a significant error.
Please CC [email protected] on v2, he was doing something similar
recently.
On Wed, Nov 22, 2023 at 08:10:58PM -0800, Jakub Kicinski wrote:
> Please CC [email protected] on v2, he was doing something similar
> recently.
+1
Thanks,
Richard