1 files changed, 93 insertions, 0 deletions
diff --git a/drivers/s390/scsi/zfcp_diag.c b/drivers/s390/scsi/zfcp_diag.c
new file mode 100644
index 000000000000..fa1b25f3ec3c
--- /dev/null
+++ b/drivers/s390/scsi/zfcp_diag.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * zfcp device driver
+ *
+ * Functions to handle diagnostics.
+ *
+ * Copyright IBM Corp. 2018
+ */
+
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+#include "zfcp_diag.h"
+#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)
+
+/**
+ * zfcp_diag_adapter_setup() - Setup storage for adapter diagnostics.
+ * @adapter: the adapter to setup diagnostics for.
+ *
+ * Creates the data-structures to store the diagnostics for an adapter. This
+ * overwrites whatever was stored before at &zfcp_adapter->diagnostics!
+ *
+ * Return:
+ * * 0	     - Everyting is OK
+ * * -ENOMEM - Could not allocate all/parts of the data-structures;
+ *	       &zfcp_adapter->diagnostics remains unchanged
+ */
+int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
+{
+	struct zfcp_diag_adapter *diag;
+	struct zfcp_diag_header *hdr;
+
+	diag = kzalloc(sizeof(*diag), GFP_KERNEL);
+	if (diag == NULL)
+		return -ENOMEM;
+
+	/* 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);
+	/* set the timestamp so that the first test on age will always fail */
+	hdr->timestamp = jiffies - msecs_to_jiffies(ZFCP_DIAG_MAX_AGE);
+
+	adapter->diagnostics = diag;
+	return 0;
+}
+
+/**
+ * zfcp_diag_adapter_free() - Frees all adapter diagnostics allocations.
+ * @adapter: the adapter whose diagnostic structures should be freed.
+ *
+ * Frees all data-structures in the given adapter that store diagnostics
+ * information. Can savely be called with partially setup diagnostics.
+ */
+void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter)
+{
+	kfree(adapter->diagnostics);
+	adapter->diagnostics = NULL;
+}
+
+/**
+ * zfcp_diag_update_xdata() - Update a diagnostics buffer.
+ * @hdr: the meta data to update.
+ * @data: data to use for the update.
+ * @incomplete: flag stating whether the data in @data is incomplete.
+ */
+void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
+			    const void *const data, const bool incomplete)
+{
+	const unsigned long capture_timestamp = jiffies;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hdr->access_lock, flags);
+
+	/* make sure we never go into the past with an update */
+	if (!time_after_eq(capture_timestamp, hdr->timestamp))
+		goto out;
+
+	hdr->timestamp = capture_timestamp;
+	hdr->incomplete = incomplete;
+	memcpy(hdr->buffer, data, hdr->buffer_size);
+out:
+	spin_unlock_irqrestore(&hdr->access_lock, flags);
+}