ptp: add kernel API ptp_get_vclocks_index()

Add kernel API ptp_get_vclocks_index() to get all ptp
vclocks index on pclock.

This is preparation for supporting ptp vclocks info query
through ethtool.

Signed-off-by: Yangbo Lu <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/ptp/ptp_clock.c

···
 #define PTP_PPS_EVENT PPS_CAPTUREASSERT
 #define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
 
+struct class *ptp_class;
+
 /* private globals */
 
 static dev_t ptp_devt;
-static struct class *ptp_class;
 
 static DEFINE_IDA(ptp_clocks_map);
 

drivers/ptp/ptp_private.h

···
 	return in_use;
 }
 
+extern struct class *ptp_class;
+
 /*
  * see ptp_chardev.c
  */

drivers/ptp/ptp_vclock.c

···
 	ptp_clock_unregister(vclock->clock);
 	kfree(vclock);
 }
+
+int ptp_get_vclocks_index(int pclock_index, int **vclock_index)
+{
+	char name[PTP_CLOCK_NAME_LEN] = "";
+	struct ptp_clock *ptp;
+	struct device *dev;
+	int num = 0;
+
+	if (pclock_index < 0)
+		return num;
+
+	snprintf(name, PTP_CLOCK_NAME_LEN, "ptp%d", pclock_index);
+	dev = class_find_device_by_name(ptp_class, name);
+	if (!dev)
+		return num;
+
+	ptp = dev_get_drvdata(dev);
+
+	if (mutex_lock_interruptible(&ptp->n_vclocks_mux)) {
+		put_device(dev);
+		return num;
+	}
+
+	*vclock_index = kzalloc(sizeof(int) * ptp->n_vclocks, GFP_KERNEL);
+	if (!(*vclock_index))
+		goto out;
+
+	memcpy(*vclock_index, ptp->vclock_index, sizeof(int) * ptp->n_vclocks);
+	num = ptp->n_vclocks;
+out:
+	mutex_unlock(&ptp->n_vclocks_mux);
+	put_device(dev);
+	return num;
+}
+EXPORT_SYMBOL(ptp_get_vclocks_index);

include/linux/ptp_clock_kernel.h

···
  */
 void ptp_cancel_worker_sync(struct ptp_clock *ptp);
 
+/**
+ * ptp_get_vclocks_index() - get all vclocks index on pclock, and
+ *                           caller is responsible to free memory
+ *                           of vclock_index
+ *
+ * @pclock_index: phc index of ptp pclock.
+ * @vclock_index: pointer to pointer of vclock index.
+ *
+ * return number of vclocks.
+ */
+int ptp_get_vclocks_index(int pclock_index, int **vclock_index);
+
 #else
 static inline struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 						   struct device *parent)
···
 { return -EOPNOTSUPP; }
 static inline void ptp_cancel_worker_sync(struct ptp_clock *ptp)
 { }
+static inline int ptp_get_vclocks_index(int pclock_index, int **vclock_index)
+{ return 0; }
 
 #endif