ptp: ocp: Expose clock status drift and offset

Monitoring of clock variance could be done through checking
the offset and the drift updates that are applied to atomic
clocks.  Expose these values as attributes for the timecard.
Signed-off-by: Vadim Fedorenko <vadfed@fb.com>
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ptp/ptp_ocp.c

@@ -52,6 +52,8 @@ struct ocp_reg {
 	u32	servo_offset_i;
 	u32	servo_drift_p;
 	u32	servo_drift_i;
+	u32	status_offset;
+	u32	status_drift;
 };
 
 #define OCP_CTRL_ENABLE		BIT(0)
@@ -1935,6 +1937,36 @@ available_clock_sources_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(available_clock_sources);
 
+static ssize_t
+clock_status_drift_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct ptp_ocp *bp = dev_get_drvdata(dev);
+	u32 val;
+	int res;
+
+	val = ioread32(&bp->reg->status_drift);
+	res = (val & ~INT_MAX) ? -1 : 1;
+	res *= (val & INT_MAX);
+	return sysfs_emit(buf, "%d\n", res);
+}
+static DEVICE_ATTR_RO(clock_status_drift);
+
+static ssize_t
+clock_status_offset_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct ptp_ocp *bp = dev_get_drvdata(dev);
+	u32 val;
+	int res;
+
+	val = ioread32(&bp->reg->status_offset);
+	res = (val & ~INT_MAX) ? -1 : 1;
+	res *= (val & INT_MAX);
+	return sysfs_emit(buf, "%d\n", res);
+}
+static DEVICE_ATTR_RO(clock_status_offset);
+
 static struct attribute *timecard_attrs[] = {
 	&dev_attr_serialnum.attr,
 	&dev_attr_gnss_sync.attr,
@@ -1946,6 +1978,8 @@ static struct attribute *timecard_attrs[] = {
 	&dev_attr_sma4.attr,
 	&dev_attr_available_sma_inputs.attr,
 	&dev_attr_available_sma_outputs.attr,
+	&dev_attr_clock_status_drift.attr,
+	&dev_attr_clock_status_offset.attr,
 	&dev_attr_irig_b_mode.attr,
 	&dev_attr_utc_tai_offset.attr,
 	&dev_attr_ts_window_adjust.attr,