On Wed, Aug 30, 2023 at 11:41:01PM +0200, Xabier Marquiegui wrote:

+ssize_t ptp_dmtsc_read(struct file *file, char __user *buf, size_t cnt,
+		       loff_t *offset)
+{
+	struct ptp_dmtsc_cdev_info *cdev = file->private_data;
+
+	return ptp_queue_read(cdev->pclock, buf, cnt, cdev->minor);
+}
+
+static const struct file_operations fops = {
+						.owner = THIS_MODULE,
+						.open = ptp_dmtsc_open,
+						.read = ptp_dmtsc_read,
+						.release = ptp_dmtsc_release
+						};

I'll say it again... There is no need to add a new char dev!

You will need a patch series of at least three patches, step by step:

1. Delete ptp_clock.tsevq
   Replace it will a linked list of `struct timestamp_event_queue`
   Populate the list with ONE queue in ptp_clock_register()

   This will be your first patch.
   It will have the same functionality as before.

2. Allocate a new `struct timestamp_event_queue` on posix_clock_operations.open()
   Add it into the list.
   Remove it again on posix_clock_operations.release()

   This will introduce new functionality, as all events will go to all
   consumers.

3. Introduce a new ioctl that filters events based on user preference.

Hm?

Thanks,
Richard