pnet.c

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