1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  IBM System z PNET ID Support
4 *
5 *    Copyright IBM Corp. 2018
6 */
7
8#include <linux/device.h>
9#include <linux/module.h>
10#include <linux/pci.h>
11#include <linux/types.h>
12#include <asm/ccwgroup.h>
13#include <asm/ccwdev.h>
14#include <asm/pnet.h>
15#include <asm/ebcdic.h>
16
17#define PNETIDS_LEN		64	/* Total utility string length in bytes
18					 * to cover up to 4 PNETIDs of 16 bytes
19					 * for up to 4 device ports
20					 */
21#define MAX_PNETID_LEN		16	/* Max.length of a single port PNETID */
22#define MAX_PNETID_PORTS	(PNETIDS_LEN / MAX_PNETID_LEN)
23					/* Max. # of ports with a PNETID */
24
25/*
26 * Get the PNETIDs from a device.
27 * s390 hardware supports the definition of a so-called Physical Network
28 * Identifier (short PNETID) per network device port. These PNETIDs can be
29 * used to identify network devices that are attached to the same physical
30 * network (broadcast domain).
31 *
32 * The device can be
33 * - a ccwgroup device with all bundled subchannels having the same PNETID
34 * - a PCI attached network device
35 *
36 * Returns:
37 * 0:		PNETIDs extracted from device.
38 * -ENOMEM:	No memory to extract utility string.
39 * -EOPNOTSUPP: Device type without utility string support
40 */
41static int pnet_ids_by_device(struct device *dev, u8 *pnetids)
42{
43	memset(pnetids, 0, PNETIDS_LEN);
44	if (dev_is_ccwgroup(dev)) {
45		struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
46		u8 *util_str;
47
48		util_str = ccw_device_get_util_str(gdev->cdev[0], 0);
49		if (!util_str)
50			return -ENOMEM;
51		memcpy(pnetids, util_str, PNETIDS_LEN);
52		EBCASC(pnetids, PNETIDS_LEN);
53		kfree(util_str);
54		return 0;
55	}
56	if (dev_is_pci(dev)) {
57		struct zpci_dev *zdev = to_zpci(to_pci_dev(dev));
58
59		memcpy(pnetids, zdev->util_str, sizeof(zdev->util_str));
60		EBCASC(pnetids, sizeof(zdev->util_str));
61		return 0;
62	}
63	return -EOPNOTSUPP;
64}
65
66/*
67 * Extract the pnetid for a device port.
68 *
69 * Return 0 if a pnetid is found and -ENOENT otherwise.
70 */
71int pnet_id_by_dev_port(struct device *dev, unsigned short port, u8 *pnetid)
72{
73	u8 pnetids[MAX_PNETID_PORTS][MAX_PNETID_LEN];
74	static const u8 zero[MAX_PNETID_LEN] = { 0 };
75	int rc = 0;
76
77	if (!dev || port >= MAX_PNETID_PORTS)
78		return -ENOENT;
79
80	if (!pnet_ids_by_device(dev, (u8 *)pnetids) &&
81	    memcmp(pnetids[port], zero, MAX_PNETID_LEN))
82		memcpy(pnetid, pnetids[port], MAX_PNETID_LEN);
83	else
84		rc = -ENOENT;
85
86	return rc;
87}
88EXPORT_SYMBOL_GPL(pnet_id_by_dev_port);
89
90MODULE_DESCRIPTION("pnetid determination from utility strings");
91MODULE_LICENSE("GPL");
92