diff --git a/drivers/s390/scsi/zfcp_diag.c b/drivers/s390/scsi/zfcp_diag.c
index 5ef7b3288c6f..67a8f4e57db1 100644
--- a/drivers/s390/scsi/zfcp_diag.c
+++ b/drivers/s390/scsi/zfcp_diag.c
@@ -19,9 +19,6 @@
 #include "zfcp_ext.h"
 #include "zfcp_def.h"
 
-/* Max age of data in a diagnostics buffer before it needs a refresh (in ms). */
-#define ZFCP_DIAG_MAX_AGE (5 * 1000)
-
 static DECLARE_WAIT_QUEUE_HEAD(__zfcp_diag_publish_wait);
 
 /**
@@ -38,9 +35,6 @@ static DECLARE_WAIT_QUEUE_HEAD(__zfcp_diag_publish_wait);
  */
 int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
 {
-	/* set the timestamp so that the first test on age will always fail */
-	const unsigned long initial_timestamp =
-		jiffies - msecs_to_jiffies(ZFCP_DIAG_MAX_AGE);
 	struct zfcp_diag_adapter *diag;
 	struct zfcp_diag_header *hdr;
 
@@ -48,13 +42,16 @@ int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
 	if (diag == NULL)
 		return -ENOMEM;
 
+	diag->max_age = (5 * 1000); /* default value: 5 s */
+
 	/* setup header for port_data */
 	hdr = &diag->port_data.header;
 
 	spin_lock_init(&hdr->access_lock);
 	hdr->buffer = &diag->port_data.data;
 	hdr->buffer_size = sizeof(diag->port_data.data);
-	hdr->timestamp = initial_timestamp;
+	/* set the timestamp so that the first test on age will always fail */
+	hdr->timestamp = jiffies - msecs_to_jiffies(diag->max_age);
 
 	/* setup header for config_data */
 	hdr = &diag->config_data.header;
@@ -62,7 +59,8 @@ int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
 	spin_lock_init(&hdr->access_lock);
 	hdr->buffer = &diag->config_data.data;
 	hdr->buffer_size = sizeof(diag->config_data.data);
-	hdr->timestamp = initial_timestamp;
+	/* set the timestamp so that the first test on age will always fail */
+	hdr->timestamp = jiffies - msecs_to_jiffies(diag->max_age);
 
 	adapter->diagnostics = diag;
 	return 0;
@@ -240,7 +238,8 @@ static int __zfcp_diag_update_buffer(struct zfcp_adapter *const adapter,
 }
 
 static bool
-__zfcp_diag_test_buffer_age_isfresh(const struct zfcp_diag_header *const hdr)
+__zfcp_diag_test_buffer_age_isfresh(const struct zfcp_diag_adapter *const diag,
+				    const struct zfcp_diag_header *const hdr)
 	__must_hold(hdr->access_lock)
 {
 	const unsigned long now = jiffies;
@@ -252,7 +251,7 @@ __zfcp_diag_test_buffer_age_isfresh(const struct zfcp_diag_header *const hdr)
 	if (!time_after_eq(now, hdr->timestamp))
 		return false;
 
-	if (jiffies_to_msecs(now - hdr->timestamp) >= ZFCP_DIAG_MAX_AGE)
+	if (jiffies_to_msecs(now - hdr->timestamp) >= diag->max_age)
 		return false;
 
 	return true;
@@ -291,7 +290,9 @@ int zfcp_diag_update_buffer_limited(struct zfcp_adapter *const adapter,
 
 	spin_lock_irqsave(&hdr->access_lock, flags);
 
-	for (rc = 0; !__zfcp_diag_test_buffer_age_isfresh(hdr); rc = 0) {
+	for (rc = 0;
+	     !__zfcp_diag_test_buffer_age_isfresh(adapter->diagnostics, hdr);
+	     rc = 0) {
 		rc = __zfcp_diag_update_buffer(adapter, hdr, buffer_update,
 					       &flags);
 		if (rc != -EAGAIN)
diff --git a/drivers/s390/scsi/zfcp_diag.h b/drivers/s390/scsi/zfcp_diag.h
index cf2947cd8c8f..b9c93d15f67c 100644
--- a/drivers/s390/scsi/zfcp_diag.h
+++ b/drivers/s390/scsi/zfcp_diag.h
@@ -42,6 +42,8 @@ struct zfcp_diag_header {
  *			      adapter.
  * @sysfs_established: flag showing that the associated sysfs-group was created
  *		       during run of zfcp_adapter_enqueue().
+ * @max_age: maximum age of data in diagnostic buffers before they need to be
+ *	     refreshed (in ms).
  * @port_data: data retrieved using exchange port data.
  * @port_data.header: header with metadata for the cache in @port_data.data.
  * @port_data.data: cached QTCB Bottom of command exchange port data.
@@ -52,6 +54,8 @@ struct zfcp_diag_header {
 struct zfcp_diag_adapter {
 	u64	sysfs_established	:1;
 
+	unsigned long	max_age;
+
 	struct {
 		struct zfcp_diag_header		header;
 		struct fsf_qtcb_bottom_port	data;
diff --git a/drivers/s390/scsi/zfcp_sysfs.c b/drivers/s390/scsi/zfcp_sysfs.c
index ae8e9137f448..494b9fe9cc94 100644
--- a/drivers/s390/scsi/zfcp_sysfs.c
+++ b/drivers/s390/scsi/zfcp_sysfs.c
@@ -326,6 +326,50 @@ static ssize_t zfcp_sysfs_port_remove_store(struct device *dev,
 static ZFCP_DEV_ATTR(adapter, port_remove, S_IWUSR, NULL,
 		     zfcp_sysfs_port_remove_store);
 
+static ssize_t
+zfcp_sysfs_adapter_diag_max_age_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(to_ccwdev(dev));
+	ssize_t rc;
+
+	if (!adapter)
+		return -ENODEV;
+
+	/* ceil(log(2^64 - 1) / log(10)) = 20 */
+	rc = scnprintf(buf, 20 + 2, "%lu\n", adapter->diagnostics->max_age);
+
+	zfcp_ccw_adapter_put(adapter);
+	return rc;
+}
+
+static ssize_t
+zfcp_sysfs_adapter_diag_max_age_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct zfcp_adapter *adapter = zfcp_ccw_adapter_by_cdev(to_ccwdev(dev));
+	unsigned long max_age;
+	ssize_t rc;
+
+	if (!adapter)
+		return -ENODEV;
+
+	rc = kstrtoul(buf, 10, &max_age);
+	if (rc != 0)
+		goto out;
+
+	adapter->diagnostics->max_age = max_age;
+
+	rc = count;
+out:
+	zfcp_ccw_adapter_put(adapter);
+	return rc;
+}
+static ZFCP_DEV_ATTR(adapter, diag_max_age, 0644,
+		     zfcp_sysfs_adapter_diag_max_age_show,
+		     zfcp_sysfs_adapter_diag_max_age_store);
+
 static struct attribute *zfcp_adapter_attrs[] = {
 	&dev_attr_adapter_failed.attr,
 	&dev_attr_adapter_in_recovery.attr,
@@ -338,6 +382,7 @@ static struct attribute *zfcp_adapter_attrs[] = {
 	&dev_attr_adapter_lic_version.attr,
 	&dev_attr_adapter_status.attr,
 	&dev_attr_adapter_hardware_version.attr,
+	&dev_attr_adapter_diag_max_age.attr,
 	NULL
 };
 
