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, &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 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 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 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 }; 114 115 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 }; 141 142 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 } 154 155 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 } 195 196 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); 202 203 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 }; 215 216 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