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 | static bool device_has_acpi_name(struct device *dev) |
37 | { |
38 | #ifdef CONFIG_ACPI |
39 | acpi_handle handle = ACPI_HANDLE(dev); |
40 | |
41 | if (!handle) |
42 | return false; |
43 | |
44 | return acpi_check_dsm(handle, guid: &pci_acpi_dsm_guid, rev: 0x2, |
45 | funcs: 1 << DSM_PCI_DEVICE_NAME); |
46 | #else |
47 | return false; |
48 | #endif |
49 | } |
50 | |
51 | #ifdef CONFIG_DMI |
52 | enum smbios_attr_enum { |
53 | SMBIOS_ATTR_NONE = 0, |
54 | SMBIOS_ATTR_LABEL_SHOW, |
55 | SMBIOS_ATTR_INSTANCE_SHOW, |
56 | }; |
57 | |
58 | static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf, |
59 | enum smbios_attr_enum attribute) |
60 | { |
61 | const struct dmi_device *dmi; |
62 | struct dmi_dev_onboard *donboard; |
63 | int domain_nr = pci_domain_nr(bus: pdev->bus); |
64 | int bus = pdev->bus->number; |
65 | int devfn = pdev->devfn; |
66 | |
67 | dmi = NULL; |
68 | while ((dmi = dmi_find_device(type: DMI_DEV_TYPE_DEV_ONBOARD, |
69 | NULL, from: dmi)) != NULL) { |
70 | donboard = dmi->device_data; |
71 | if (donboard && donboard->segment == domain_nr && |
72 | donboard->bus == bus && |
73 | donboard->devfn == devfn) { |
74 | if (buf) { |
75 | if (attribute == SMBIOS_ATTR_INSTANCE_SHOW) |
76 | return sysfs_emit(buf, fmt: "%d\n" , |
77 | donboard->instance); |
78 | else if (attribute == SMBIOS_ATTR_LABEL_SHOW) |
79 | return sysfs_emit(buf, fmt: "%s\n" , |
80 | dmi->name); |
81 | } |
82 | return strlen(dmi->name); |
83 | } |
84 | } |
85 | return 0; |
86 | } |
87 | |
88 | static ssize_t smbios_label_show(struct device *dev, |
89 | struct device_attribute *attr, char *buf) |
90 | { |
91 | struct pci_dev *pdev = to_pci_dev(dev); |
92 | |
93 | return find_smbios_instance_string(pdev, buf, |
94 | attribute: SMBIOS_ATTR_LABEL_SHOW); |
95 | } |
96 | static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444, |
97 | smbios_label_show, NULL); |
98 | |
99 | static ssize_t index_show(struct device *dev, struct device_attribute *attr, |
100 | char *buf) |
101 | { |
102 | struct pci_dev *pdev = to_pci_dev(dev); |
103 | |
104 | return find_smbios_instance_string(pdev, buf, |
105 | attribute: SMBIOS_ATTR_INSTANCE_SHOW); |
106 | } |
107 | static DEVICE_ATTR_RO(index); |
108 | |
109 | static struct attribute *smbios_attrs[] = { |
110 | &dev_attr_smbios_label.attr, |
111 | &dev_attr_index.attr, |
112 | NULL, |
113 | }; |
114 | |
115 | static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a, |
116 | int n) |
117 | { |
118 | struct device *dev = kobj_to_dev(kobj); |
119 | struct pci_dev *pdev = to_pci_dev(dev); |
120 | |
121 | if (device_has_acpi_name(dev)) |
122 | return 0; |
123 | |
124 | if (!find_smbios_instance_string(pdev, NULL, attribute: SMBIOS_ATTR_NONE)) |
125 | return 0; |
126 | |
127 | return a->mode; |
128 | } |
129 | |
130 | const struct attribute_group pci_dev_smbios_attr_group = { |
131 | .attrs = smbios_attrs, |
132 | .is_visible = smbios_attr_is_visible, |
133 | }; |
134 | #endif |
135 | |
136 | #ifdef CONFIG_ACPI |
137 | enum acpi_attr_enum { |
138 | ACPI_ATTR_LABEL_SHOW, |
139 | ACPI_ATTR_INDEX_SHOW, |
140 | }; |
141 | |
142 | static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf) |
143 | { |
144 | int len; |
145 | |
146 | len = utf16s_to_utf8s(pwcs: (const wchar_t *)obj->buffer.pointer, |
147 | len: obj->buffer.length, |
148 | endian: UTF16_LITTLE_ENDIAN, |
149 | s: buf, PAGE_SIZE - 1); |
150 | buf[len++] = '\n'; |
151 | |
152 | return len; |
153 | } |
154 | |
155 | static int dsm_get_label(struct device *dev, char *buf, |
156 | enum acpi_attr_enum attr) |
157 | { |
158 | acpi_handle handle = ACPI_HANDLE(dev); |
159 | union acpi_object *obj, *tmp; |
160 | int len = 0; |
161 | |
162 | if (!handle) |
163 | return -1; |
164 | |
165 | obj = acpi_evaluate_dsm(handle, guid: &pci_acpi_dsm_guid, rev: 0x2, |
166 | DSM_PCI_DEVICE_NAME, NULL); |
167 | if (!obj) |
168 | return -1; |
169 | |
170 | tmp = obj->package.elements; |
171 | if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 && |
172 | tmp[0].type == ACPI_TYPE_INTEGER && |
173 | (tmp[1].type == ACPI_TYPE_STRING || |
174 | tmp[1].type == ACPI_TYPE_BUFFER)) { |
175 | /* |
176 | * The second string element is optional even when |
177 | * this _DSM is implemented; when not implemented, |
178 | * this entry must return a null string. |
179 | */ |
180 | if (attr == ACPI_ATTR_INDEX_SHOW) { |
181 | len = sysfs_emit(buf, fmt: "%llu\n" , tmp->integer.value); |
182 | } else if (attr == ACPI_ATTR_LABEL_SHOW) { |
183 | if (tmp[1].type == ACPI_TYPE_STRING) |
184 | len = sysfs_emit(buf, fmt: "%s\n" , |
185 | tmp[1].string.pointer); |
186 | else if (tmp[1].type == ACPI_TYPE_BUFFER) |
187 | len = dsm_label_utf16s_to_utf8s(obj: tmp + 1, buf); |
188 | } |
189 | } |
190 | |
191 | ACPI_FREE(obj); |
192 | |
193 | return len > 0 ? len : -1; |
194 | } |
195 | |
196 | static ssize_t label_show(struct device *dev, struct device_attribute *attr, |
197 | char *buf) |
198 | { |
199 | return dsm_get_label(dev, buf, attr: ACPI_ATTR_LABEL_SHOW); |
200 | } |
201 | static DEVICE_ATTR_RO(label); |
202 | |
203 | static ssize_t acpi_index_show(struct device *dev, |
204 | struct device_attribute *attr, char *buf) |
205 | { |
206 | return dsm_get_label(dev, buf, attr: ACPI_ATTR_INDEX_SHOW); |
207 | } |
208 | static DEVICE_ATTR_RO(acpi_index); |
209 | |
210 | static struct attribute *acpi_attrs[] = { |
211 | &dev_attr_label.attr, |
212 | &dev_attr_acpi_index.attr, |
213 | NULL, |
214 | }; |
215 | |
216 | static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a, |
217 | int n) |
218 | { |
219 | struct device *dev = kobj_to_dev(kobj); |
220 | |
221 | if (!device_has_acpi_name(dev)) |
222 | return 0; |
223 | |
224 | return a->mode; |
225 | } |
226 | |
227 | const struct attribute_group pci_dev_acpi_attr_group = { |
228 | .attrs = acpi_attrs, |
229 | .is_visible = acpi_attr_is_visible, |
230 | }; |
231 | #endif |
232 | |