The interface to the Linux kernel for adjusting clock frequencies is
specified in scaled parts per million, where the frequency field is parts
per million with a 16 bit binary fractional field. (Equivalently it is
parts per ~65 billion).
The frequency adjustment is stored internally as a double, even though when
displaying we always display only a whole number adjustment. Thus ptp4l and
phc2sys already use the full range of frequency adjustments that can be
specified using a double type.
However, when initializing the servo we read the current clock frequency
and cast it to an integer, discarding the fractional part below a part per
billion.
Refactor the servo_create API to take a double value instead of an integer
value. Fix the clockadj_get_freq and clockadj_set_freq initialization to
avoid casting to an integer and thus rounding the value.
Signed-off-by: Jacob Keller
---
Noticed this while investigating whether we supported the full range of the
frequency adjustment.
clock.c | 10 ++
linreg.c | 2 +-
linreg.h | 2 +-
pi.c | 2 +-
pi.h | 2 +-
servo.c | 2 +-
servo.h | 2 +-
ts2phc.c | 5 +++--
8 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/clock.c b/clock.c
index d37bb87b6c03..7decd836feda 100644
--- a/clock.c
+++ b/clock.c
@@ -897,10 +897,11 @@ struct clock *clock_create(enum clock_type type, struct
config *config,
enum servo_type servo = config_get_int(config, NULL, "clock_servo");
char ts_label[IF_NAMESIZE], phc[32], *tmp;
enum timestamp_type timestamping;
- int fadj = 0, max_adj = 0, sw_ts;
int phc_index, conf_phc_index, required_modes = 0;
struct clock *c = _clock;
+ int max_adj = 0, sw_ts;
const char *uds_ifname;
+ double fadj = 0.0;
struct port *p;
unsigned char oui[OUI_LEN];
struct interface *iface;
@@ -1143,7 +1144,7 @@ struct clock *clock_create(enum clock_type type, struct
config *config,
c->time_flags = c->utc_timescale ? 0 : PTP_TIMESCALE;
if (c->clkid != CLOCK_INVALID) {
- fadj = (int) clockadj_get_freq(c->clkid);
+ fadj = clockadj_get_freq(c->clkid);
/* Due to a bug in older kernels, the reading may silently fail
and return 0. Set the frequency back to make sure fadj is
the actual frequency of the clock. */
@@ -1738,9 +1739,10 @@ struct tsproc *clock_get_tsproc(struct clock *c)
int clock_switch_phc(struct clock *c, int phc_index)
{
struct servo *servo;
- int fadj, max_adj;
clockid_t clkid;
char phc[32];
+ double fadj;
+ int max_adj;
snprintf(phc, sizeof(phc), "/dev/ptp%d", phc_index);
clkid = phc_open(phc);
@@ -1754,7 +1756,7 @@ int clock_switch_phc(struct clock *c, int phc_index)
phc_close(clkid);
return -1;
}
- fadj = (int) clockadj_get_freq(clkid);
+ fadj = clockadj_get_freq(clkid);
clockadj_set_freq(clkid, fadj);
servo = servo_create(c->config, c->servo_type, -fadj, max_adj, 0);
if (!servo) {
diff --git a/linreg.c b/linreg.c
index 8f354f4b0d0b..363636e16937 100644
--- a/linreg.c
+++ b/linreg.c
@@ -330,7 +330,7 @@ static void linreg_leap(struct servo *servo, int leap)
s->leap = leap;
}
-struct servo *linreg_servo_create(int fadj)
+struct servo *linreg_servo_create(double fadj)
{
struct linreg_servo *s;
diff --git a/linreg.h b/linreg.h
index 5c86ea76ebf2..3c48ce5d465a 100644
--- a/linreg.h
+++ b/linreg.h
@@ -21,6 +21,6 @@
#include "servo.h"
-struct servo *linreg_servo_create(int fadj);
+struct servo *linreg_servo_create(double fadj);
#endif
diff --git a/pi.c b/pi.c
index bfe50223d96a..4a96a5b1913b 100644
--- a/pi.c
+++ b/pi.c
@@ -177,7 +177,7 @@ static void pi_reset(struct servo *servo)
s->count = 0;
}
-struct servo *pi_servo_create(struct config *cfg, int fadj, int sw_ts)
+struct servo *pi_servo_create(struct config *cfg, double fadj, int sw_ts)
{
struct pi_servo *s;
diff --git a/pi.h b/pi.h
index feb3ebeb25b9..1e7eb4f3fd51 100644
--- a/pi.h
+++ b/pi.h
@@ -21,6 +21,6 @@
#include "servo.h"
-struct servo *pi_servo_create(struct config *cfg, int fadj, int sw_ts);
+struct servo *pi_servo_create(struct config *cfg, double fadj, int sw_ts);
#endif
diff --git a/servo.c b/servo.c
index 46042aa176d9..6ba7cb42c71e 100644
--- a/servo.c
+++ b/servo.c
@@ -31,7 +31,7 @@
#define NSEC_PER_SEC 10
struct servo *servo_create(struct config *cfg, enum servo_type type,
- int fadj, int max_ppb, int sw_ts)
+ double fadj, int max_ppb, int sw_ts)
{
double servo_first_step_threshold;
double servo_step_threshold;
diff --git a/servo.h b/servo.h
index 6c30d3341fa6..6cedb66ada03 100644
--- a/servo.h
+++ b/servo.h
@@ -77,7 +77,7 @@ enum servo_state {
* @return A pointer to a new servo on success, NULL
