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   */
pnet_ids_by_device(struct device * dev,u8 * pnetids)41  static 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   */
pnet_id_by_dev_port(struct device * dev,unsigned short port,u8 * pnetid)71  int 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  }
88  EXPORT_SYMBOL_GPL(pnet_id_by_dev_port);
89  
90  MODULE_DESCRIPTION("pnetid determination from utility strings");
91  MODULE_LICENSE("GPL");
92