1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Export the firmware instance and label associated with a PCI device to
4 * sysfs
5 *
6 * Copyright (C) 2010 Dell Inc.
7 * by Narendra K <Narendra_K@dell.com>,
8 * Jordan Hargrave <Jordan_Hargrave@dell.com>
9 *
10 * PCI Firmware Specification Revision 3.1 section 4.6.7 (DSM for Naming a
11 * PCI or PCI Express Device Under Operating Systems) defines an instance
12 * number and string name. This code retrieves them and exports them to sysfs.
13 * If the system firmware does not provide the ACPI _DSM (Device Specific
14 * Method), then the SMBIOS type 41 instance number and string is exported to
15 * sysfs.
16 *
17 * SMBIOS defines type 41 for onboard pci devices. This code retrieves
18 * the instance number and string from the type 41 record and exports
19 * it to sysfs.
20 *
21 * Please see https://linux.dell.com/files/biosdevname/ for more
22 * information.
23 */
24
25#include <linux/dmi.h>
26#include <linux/sysfs.h>
27#include <linux/pci.h>
28#include <linux/pci_ids.h>
29#include <linux/module.h>
30#include <linux/device.h>
31#include <linux/nls.h>
32#include <linux/acpi.h>
33#include <linux/pci-acpi.h>
34#include "pci.h"
35
36#ifdef CONFIG_DMI
37enum smbios_attr_enum {
38	SMBIOS_ATTR_NONE = 0,
39	SMBIOS_ATTR_LABEL_SHOW,
40	SMBIOS_ATTR_INSTANCE_SHOW,
41};
42
43static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf,
44					  enum smbios_attr_enum attribute)
45{
46	const struct dmi_device *dmi;
47	struct dmi_dev_onboard *donboard;
48	int domain_nr;
49	int bus;
50	int devfn;
51
52	domain_nr = pci_domain_nr(pdev->bus);
53	bus = pdev->bus->number;
54	devfn = pdev->devfn;
55
56	dmi = NULL;
57	while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,
58				      NULL, dmi)) != NULL) {
59		donboard = dmi->device_data;
60		if (donboard && donboard->segment == domain_nr &&
61				donboard->bus == bus &&
62				donboard->devfn == devfn) {
63			if (buf) {
64				if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)
65					return scnprintf(buf, PAGE_SIZE,
66							 "%d\n",
67							 donboard->instance);
68				else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
69					return scnprintf(buf, PAGE_SIZE,
70							 "%s\n",
71							 dmi->name);
72			}
73			return strlen(dmi->name);
74		}
75	}
76	return 0;
77}
78
79static umode_t smbios_instance_string_exist(struct kobject *kobj,
80					    struct attribute *attr, int n)
81{
82	struct device *dev;
83	struct pci_dev *pdev;
84
85	dev = kobj_to_dev(kobj);
86	pdev = to_pci_dev(dev);
87
88	return find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE) ?
89					   S_IRUGO : 0;
90}
91
92static ssize_t smbioslabel_show(struct device *dev,
93				struct device_attribute *attr, char *buf)
94{
95	struct pci_dev *pdev;
96	pdev = to_pci_dev(dev);
97
98	return find_smbios_instance_string(pdev, buf,
99					   SMBIOS_ATTR_LABEL_SHOW);
100}
101
102static ssize_t smbiosinstance_show(struct device *dev,
103				   struct device_attribute *attr, char *buf)
104{
105	struct pci_dev *pdev;
106	pdev = to_pci_dev(dev);
107
108	return find_smbios_instance_string(pdev, buf,
109					   SMBIOS_ATTR_INSTANCE_SHOW);
110}
111
112static struct device_attribute smbios_attr_label = {
113	.attr = {.name = "label", .mode = 0444},
114	.show = smbioslabel_show,
115};
116
117static struct device_attribute smbios_attr_instance = {
118	.attr = {.name = "index", .mode = 0444},
119	.show = smbiosinstance_show,
120};
121
122static struct attribute *smbios_attributes[] = {
123	&smbios_attr_label.attr,
124	&smbios_attr_instance.attr,
125	NULL,
126};
127
128static const struct attribute_group smbios_attr_group = {
129	.attrs = smbios_attributes,
130	.is_visible = smbios_instance_string_exist,
131};
132
133static int pci_create_smbiosname_file(struct pci_dev *pdev)
134{
135	return sysfs_create_group(&pdev->dev.kobj, &smbios_attr_group);
136}
137
138static void pci_remove_smbiosname_file(struct pci_dev *pdev)
139{
140	sysfs_remove_group(&pdev->dev.kobj, &smbios_attr_group);
141}
142#else
143static inline int pci_create_smbiosname_file(struct pci_dev *pdev)
144{
145	return -1;
146}
147
148static inline void pci_remove_smbiosname_file(struct pci_dev *pdev)
149{
150}
151#endif
152
153#ifdef CONFIG_ACPI
154enum acpi_attr_enum {
155	ACPI_ATTR_LABEL_SHOW,
156	ACPI_ATTR_INDEX_SHOW,
157};
158
159static void dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
160{
161	int len;
162	len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
163			      obj->buffer.length,
164			      UTF16_LITTLE_ENDIAN,
165			      buf, PAGE_SIZE - 1);
166	buf[len] = '\n';
167}
168
169static int dsm_get_label(struct device *dev, char *buf,
170			 enum acpi_attr_enum attr)
171{
172	acpi_handle handle;
173	union acpi_object *obj, *tmp;
174	int len = -1;
175
176	handle = ACPI_HANDLE(dev);
177	if (!handle)
178		return -1;
179
180	obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,
181				DSM_PCI_DEVICE_NAME, NULL);
182	if (!obj)
183		return -1;
184
185	tmp = obj->package.elements;
186	if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
187	    tmp[0].type == ACPI_TYPE_INTEGER &&
188	    (tmp[1].type == ACPI_TYPE_STRING ||
189	     tmp[1].type == ACPI_TYPE_BUFFER)) {
190		/*
191		 * The second string element is optional even when
192		 * this _DSM is implemented; when not implemented,
193		 * this entry must return a null string.
194		 */
195		if (attr == ACPI_ATTR_INDEX_SHOW) {
196			scnprintf(buf, PAGE_SIZE, "%llu\n", tmp->integer.value);
197		} else if (attr == ACPI_ATTR_LABEL_SHOW) {
198			if (tmp[1].type == ACPI_TYPE_STRING)
199				scnprintf(buf, PAGE_SIZE, "%s\n",
200					  tmp[1].string.pointer);
201			else if (tmp[1].type == ACPI_TYPE_BUFFER)
202				dsm_label_utf16s_to_utf8s(tmp + 1, buf);
203		}
204		len = strlen(buf) > 0 ? strlen(buf) : -1;
205	}
206
207	ACPI_FREE(obj);
208
209	return len;
210}
211
212static bool device_has_dsm(struct device *dev)
213{
214	acpi_handle handle;
215
216	handle = ACPI_HANDLE(dev);
217	if (!handle)
218		return false;
219
220	return !!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
221				1 << DSM_PCI_DEVICE_NAME);
222}
223
224static umode_t acpi_index_string_exist(struct kobject *kobj,
225				       struct attribute *attr, int n)
226{
227	struct device *dev;
228
229	dev = kobj_to_dev(kobj);
230
231	if (device_has_dsm(dev))
232		return S_IRUGO;
233
234	return 0;
235}
236
237static ssize_t acpilabel_show(struct device *dev,
238			      struct device_attribute *attr, char *buf)
239{
240	return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
241}
242
243static ssize_t acpiindex_show(struct device *dev,
244			      struct device_attribute *attr, char *buf)
245{
246	return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
247}
248
249static struct device_attribute acpi_attr_label = {
250	.attr = {.name = "label", .mode = 0444},
251	.show = acpilabel_show,
252};
253
254static struct device_attribute acpi_attr_index = {
255	.attr = {.name = "acpi_index", .mode = 0444},
256	.show = acpiindex_show,
257};
258
259static struct attribute *acpi_attributes[] = {
260	&acpi_attr_label.attr,
261	&acpi_attr_index.attr,
262	NULL,
263};
264
265static const struct attribute_group acpi_attr_group = {
266	.attrs = acpi_attributes,
267	.is_visible = acpi_index_string_exist,
268};
269
270static int pci_create_acpi_index_label_files(struct pci_dev *pdev)
271{
272	return sysfs_create_group(&pdev->dev.kobj, &acpi_attr_group);
273}
274
275static int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
276{
277	sysfs_remove_group(&pdev->dev.kobj, &acpi_attr_group);
278	return 0;
279}
280#else
281static inline int pci_create_acpi_index_label_files(struct pci_dev *pdev)
282{
283	return -1;
284}
285
286static inline int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
287{
288	return -1;
289}
290
291static inline bool device_has_dsm(struct device *dev)
292{
293	return false;
294}
295#endif
296
297void pci_create_firmware_label_files(struct pci_dev *pdev)
298{
299	if (device_has_dsm(&pdev->dev))
300		pci_create_acpi_index_label_files(pdev);
301	else
302		pci_create_smbiosname_file(pdev);
303}
304
305void pci_remove_firmware_label_files(struct pci_dev *pdev)
306{
307	if (device_has_dsm(&pdev->dev))
308		pci_remove_acpi_index_label_files(pdev);
309	else
310		pci_remove_smbiosname_file(pdev);
311}
312