ptp: support ptp physical/virtual clocks conversion

Support ptp physical/virtual clocks conversion via sysfs.
There will be a new attribute n_vclocks under ptp physical
clock sysfs.

- In default, the value is 0 meaning only ptp physical clock
  is in use.
- Setting the value can create corresponding number of ptp
  virtual clocks to use. But current physical clock is guaranteed
  to stay free running.
- Setting the value back to 0 can delete virtual clocks and back
  use physical clock again.

Another new attribute max_vclocks control the maximum number of
ptp vclocks.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 853b79b6b30e..87cb55953b69 100644
--- a/drivers/ptp/ptp_private.h
+++ b/drivers/ptp/ptp_private.h
@@ -18,6 +18,7 @@
 
 #define PTP_MAX_TIMESTAMPS 128
 #define PTP_BUF_TIMESTAMPS 30
+#define PTP_DEFAULT_MAX_VCLOCKS 20
 
 struct timestamp_event_queue {
 	struct ptp_extts_event buf[PTP_MAX_TIMESTAMPS];
@@ -46,6 +47,10 @@ struct ptp_clock {
 	const struct attribute_group *pin_attr_groups[2];
 	struct kthread_worker *kworker;
 	struct kthread_delayed_work aux_work;
+	unsigned int max_vclocks;
+	unsigned int n_vclocks;
+	struct mutex n_vclocks_mux; /* protect concurrent n_vclocks access */
+	bool is_virtual_clock;
 };
 
 #define info_to_vclock(d) container_of((d), struct ptp_vclock, info)
@@ -74,6 +79,22 @@ static inline int queue_cnt(struct timestamp_event_queue *q)
 	return cnt < 0 ? PTP_MAX_TIMESTAMPS + cnt : cnt;
 }
 
+/* Check if ptp virtual clock is in use */
+static inline bool ptp_vclock_in_use(struct ptp_clock *ptp)
+{
+	bool in_use = false;
+
+	if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+		return true;
+
+	if (!ptp->is_virtual_clock && ptp->n_vclocks)
+		in_use = true;
+
+	mutex_unlock(&ptp->n_vclocks_mux);
+
+	return in_use;
+}
+
 /*
  * see ptp_chardev.c
  */