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 
device_has_acpi_name(struct device * dev)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, &pci_acpi_dsm_guid, 0x2,
45 			      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 
find_smbios_instance_string(struct pci_dev * pdev,char * buf,enum smbios_attr_enum attribute)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(pdev->bus);
64 	int bus = pdev->bus->number;
65 	int devfn = pdev->devfn;
66 
67 	dmi = NULL;
68 	while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,
69 				      NULL, 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, "%d\n",
77 							  donboard->instance);
78 				else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
79 					return sysfs_emit(buf, "%s\n",
80 							  dmi->name);
81 			}
82 			return strlen(dmi->name);
83 		}
84 	}
85 	return 0;
86 }
87 
smbios_label_show(struct device * dev,struct device_attribute * attr,char * buf)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 					   SMBIOS_ATTR_LABEL_SHOW);
95 }
96 static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444,
97 						    smbios_label_show, NULL);
98 
index_show(struct device * dev,struct device_attribute * attr,char * buf)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 					   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 
smbios_attr_is_visible(struct kobject * kobj,struct attribute * a,int n)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, 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 
dsm_label_utf16s_to_utf8s(union acpi_object * obj,char * buf)142 static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
143 {
144 	int len;
145 
146 	len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
147 			      obj->buffer.length,
148 			      UTF16_LITTLE_ENDIAN,
149 			      buf, PAGE_SIZE - 1);
150 	buf[len++] = '\n';
151 
152 	return len;
153 }
154 
dsm_get_label(struct device * dev,char * buf,enum acpi_attr_enum attr)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, &pci_acpi_dsm_guid, 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, "%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, "%s\n",
185 						 tmp[1].string.pointer);
186 			else if (tmp[1].type == ACPI_TYPE_BUFFER)
187 				len = dsm_label_utf16s_to_utf8s(tmp + 1, buf);
188 		}
189 	}
190 
191 	ACPI_FREE(obj);
192 
193 	return len > 0 ? len : -1;
194 }
195 
label_show(struct device * dev,struct device_attribute * attr,char * buf)196 static ssize_t label_show(struct device *dev, struct device_attribute *attr,
197 			  char *buf)
198 {
199 	return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
200 }
201 static DEVICE_ATTR_RO(label);
202 
acpi_index_show(struct device * dev,struct device_attribute * attr,char * buf)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, 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 
acpi_attr_is_visible(struct kobject * kobj,struct attribute * a,int n)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