[Linuxptp-devel] [RFC PATCH 01/15] posix_clock_open: derive PHC index from device name if possible

[Vladimir O. <ol...@gm...>]

Currently the PHC index is retrieved only through an ethtool ioctl if
the PHC is specified as an Ethernet interface. If it's a char device
such as /dev/ptp5, the phc_index will remain unpopulated. Try to infer
it from the char device's path.

This is useful when trying to determine whether multiple clocks are in
fact the same (such as /dev/ptp3 and sw1p3), just compare their PHC
index.

Signed-off-by: Vladimir Oltean <ol...@gm...>
---
 util.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/util.c b/util.c
index 296dd59a08c1..027d694ea854 100644
--- a/util.c
+++ b/util.c
@@ -211,6 +211,16 @@ clockid_t posix_clock_open(const char *device, int *phc_index)
 	/* check if device is valid phc device */
 	clkid = phc_open(device);
 	if (clkid != CLOCK_INVALID) {
+		if (!strncmp(device, "/dev/ptp", strlen("/dev/ptp"))) {
+			int r = get_ranged_int(device + strlen("/dev/ptp"),
+					       phc_index, 0, 65535);
+			if (r) {
+				fprintf(stderr,
+					"failed to parse PHC index from %s\n",
+					device);
+				return -1;
+			}
+		}
 		return clkid;
 	}
 	/* check if device is a valid ethernet device */
-- 
2.25.1