1 files changed, 91 insertions, 0 deletions
diff --git a/arch/s390/net/pnet.c b/arch/s390/net/pnet.c
new file mode 100644
index 000000000..79211bec0
--- /dev/null
+++ b/arch/s390/net/pnet.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  IBM System z PNET ID Support
+ *
+ *    Copyright IBM Corp. 2018
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/types.h>
+#include <asm/ccwgroup.h>
+#include <asm/ccwdev.h>
+#include <asm/pnet.h>
+#include <asm/ebcdic.h>
+
+#define PNETIDS_LEN		64	/* Total utility string length in bytes
+					 * to cover up to 4 PNETIDs of 16 bytes
+					 * for up to 4 device ports
+					 */
+#define MAX_PNETID_LEN		16	/* Max.length of a single port PNETID */
+#define MAX_PNETID_PORTS	(PNETIDS_LEN / MAX_PNETID_LEN)
+					/* Max. # of ports with a PNETID */
+
+/*
+ * Get the PNETIDs from a device.
+ * s390 hardware supports the definition of a so-called Physical Network
+ * Identifier (short PNETID) per network device port. These PNETIDs can be
+ * used to identify network devices that are attached to the same physical
+ * network (broadcast domain).
+ *
+ * The device can be
+ * - a ccwgroup device with all bundled subchannels having the same PNETID
+ * - a PCI attached network device
+ *
+ * Returns:
+ * 0:		PNETIDs extracted from device.
+ * -ENOMEM:	No memory to extract utility string.
+ * -EOPNOTSUPP: Device type without utility string support
+ */
+static int pnet_ids_by_device(struct device *dev, u8 *pnetids)
+{
+	memset(pnetids, 0, PNETIDS_LEN);
+	if (dev_is_ccwgroup(dev)) {
+		struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
+		u8 *util_str;
+
+		util_str = ccw_device_get_util_str(gdev->cdev[0], 0);
+		if (!util_str)
+			return -ENOMEM;
+		memcpy(pnetids, util_str, PNETIDS_LEN);
+		EBCASC(pnetids, PNETIDS_LEN);
+		kfree(util_str);
+		return 0;
+	}
+	if (dev_is_pci(dev)) {
+		struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
+
+		memcpy(pnetids, zdev->util_str, sizeof(zdev->util_str));
+		EBCASC(pnetids, sizeof(zdev->util_str));
+		return 0;
+	}
+	return -EOPNOTSUPP;
+}
+
+/*
+ * Extract the pnetid for a device port.
+ *
+ * Return 0 if a pnetid is found and -ENOENT otherwise.
+ */
+int pnet_id_by_dev_port(struct device *dev, unsigned short port, u8 *pnetid)
+{
+	u8 pnetids[MAX_PNETID_PORTS][MAX_PNETID_LEN];
+	static const u8 zero[MAX_PNETID_LEN] = { 0 };
+	int rc = 0;
+
+	if (!dev || port >= MAX_PNETID_PORTS)
+		return -ENOENT;
+
+	if (!pnet_ids_by_device(dev, (u8 *)pnetids) &&
+	    memcmp(pnetids[port], zero, MAX_PNETID_LEN))
+		memcpy(pnetid, pnetids[port], MAX_PNETID_LEN);
+	else
+		rc = -ENOENT;
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(pnet_id_by_dev_port);
+
+MODULE_DESCRIPTION("pnetid determination from utility strings");
+MODULE_LICENSE("GPL");