ptp: track available ptp vclocks information

Track available ptp vclocks information. Record index values
of available ptp vclocks during registering and unregistering.

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

···
 {
 	struct ptp_clock *ptp;
 	int err = 0, index, major = MAJOR(ptp_devt);
+	size_t size;
 
 	if (info->n_alarm > PTP_MAX_ALARMS)
 		return ERR_PTR(-EINVAL);
···
 	    strcmp(parent->class->name, "ptp") == 0)
 		ptp->is_virtual_clock = true;
 
-	if (!ptp->is_virtual_clock)
+	if (!ptp->is_virtual_clock) {
 		ptp->max_vclocks = PTP_DEFAULT_MAX_VCLOCKS;
+
+		size = sizeof(int) * ptp->max_vclocks;
+		ptp->vclock_index = kzalloc(size, GFP_KERNEL);
+		if (!ptp->vclock_index) {
+			err = -ENOMEM;
+			goto no_mem_for_vclocks;
+		}
+	}
 
 	err = ptp_populate_pin_groups(ptp);
 	if (err)
···
 no_pps:
 	ptp_cleanup_pin_groups(ptp);
 no_pin_groups:
+	kfree(ptp->vclock_index);
+no_mem_for_vclocks:
 	if (ptp->kworker)
 		kthread_destroy_worker(ptp->kworker);
 kworker_err:
···
 
 	ptp->defunct = 1;
 	wake_up_interruptible(&ptp->tsev_wq);
+
+	kfree(ptp->vclock_index);
 
 	if (ptp->kworker) {
 		kthread_cancel_delayed_work_sync(&ptp->aux_work);

drivers/ptp/ptp_private.h

···
 	struct kthread_delayed_work aux_work;
 	unsigned int max_vclocks;
 	unsigned int n_vclocks;
+	int *vclock_index;
 	struct mutex n_vclocks_mux; /* protect concurrent n_vclocks access */
 	bool is_virtual_clock;
 };

drivers/ptp/ptp_sysfs.c

···
 			if (!vclock)
 				goto out;
 
+			*(ptp->vclock_index + ptp->n_vclocks + i) =
+				vclock->clock->index;
+
 			dev_info(dev, "new virtual clock ptp%d\n",
 				 vclock->clock->index);
 		}
···
 		i = ptp->n_vclocks - num;
 		device_for_each_child_reverse(dev, &i,
 					      unregister_vclock);
+
+		for (i = 1; i <= ptp->n_vclocks - num; i++)
+			*(ptp->vclock_index + ptp->n_vclocks - i) = -1;
 	}
 
 	if (num == 0)
···
 				 const char *buf, size_t count)
 {
 	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	unsigned int *vclock_index;
+	int err = -EINVAL;
+	size_t size;
 	u32 max;
 
 	if (kstrtou32(buf, 0, &max) || max == 0)
···
 	if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
 		return -ERESTARTSYS;
 
-	if (max < ptp->n_vclocks) {
-		mutex_unlock(&ptp->n_vclocks_mux);
-		return -EINVAL;
+	if (max < ptp->n_vclocks)
+		goto out;
+
+	size = sizeof(int) * max;
+	vclock_index = kzalloc(size, GFP_KERNEL);
+	if (!vclock_index) {
+		err = -ENOMEM;
+		goto out;
 	}
 
+	size = sizeof(int) * ptp->n_vclocks;
+	memcpy(vclock_index, ptp->vclock_index, size);
+
+	kfree(ptp->vclock_index);
+	ptp->vclock_index = vclock_index;
 	ptp->max_vclocks = max;
 
 	mutex_unlock(&ptp->n_vclocks_mux);
 
 	return count;
+out:
+	mutex_unlock(&ptp->n_vclocks_mux);
+	return err;
 }
 static DEVICE_ATTR_RW(max_vclocks);