diff options
Diffstat (limited to 'drivers/pci/pci-label.c')
| -rw-r--r-- | drivers/pci/pci-label.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c new file mode 100644 index 000000000..0c6446519 --- /dev/null +++ b/drivers/pci/pci-label.c @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Export the firmware instance and label associated with a PCI device to + * sysfs + * + * Copyright (C) 2010 Dell Inc. + * by Narendra K <Narendra_K@dell.com>, + * Jordan Hargrave <Jordan_Hargrave@dell.com> + * + * PCI Firmware Specification Revision 3.1 section 4.6.7 (DSM for Naming a + * PCI or PCI Express Device Under Operating Systems) defines an instance + * number and string name. This code retrieves them and exports them to sysfs. + * If the system firmware does not provide the ACPI _DSM (Device Specific + * Method), then the SMBIOS type 41 instance number and string is exported to + * sysfs. + * + * SMBIOS defines type 41 for onboard pci devices. This code retrieves + * the instance number and string from the type 41 record and exports + * it to sysfs. + * + * Please see https://linux.dell.com/files/biosdevname/ for more + * information. + */ + +#include <linux/dmi.h> +#include <linux/sysfs.h> +#include <linux/pci.h> +#include <linux/pci_ids.h> +#include <linux/module.h> +#include <linux/device.h> +#include <linux/nls.h> +#include <linux/acpi.h> +#include <linux/pci-acpi.h> +#include "pci.h" + +static bool device_has_acpi_name(struct device *dev) +{ +#ifdef CONFIG_ACPI + acpi_handle handle = ACPI_HANDLE(dev); + + if (!handle) + return false; + + return acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2, + 1 << DSM_PCI_DEVICE_NAME); +#else + return false; +#endif +} + +#ifdef CONFIG_DMI +enum smbios_attr_enum { + SMBIOS_ATTR_NONE = 0, + SMBIOS_ATTR_LABEL_SHOW, + SMBIOS_ATTR_INSTANCE_SHOW, +}; + +static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf, + enum smbios_attr_enum attribute) +{ + const struct dmi_device *dmi; + struct dmi_dev_onboard *donboard; + int domain_nr = pci_domain_nr(pdev->bus); + int bus = pdev->bus->number; + int devfn = pdev->devfn; + + dmi = NULL; + while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD, + NULL, dmi)) != NULL) { + donboard = dmi->device_data; + if (donboard && donboard->segment == domain_nr && + donboard->bus == bus && + donboard->devfn == devfn) { + if (buf) { + if (attribute == SMBIOS_ATTR_INSTANCE_SHOW) + return sysfs_emit(buf, "%d\n", + donboard->instance); + else if (attribute == SMBIOS_ATTR_LABEL_SHOW) + return sysfs_emit(buf, "%s\n", + dmi->name); + } + return strlen(dmi->name); + } + } + return 0; +} + +static ssize_t smbios_label_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct pci_dev *pdev = to_pci_dev(dev); + + return find_smbios_instance_string(pdev, buf, + SMBIOS_ATTR_LABEL_SHOW); +} +static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444, + smbios_label_show, NULL); + +static ssize_t index_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct pci_dev *pdev = to_pci_dev(dev); + + return find_smbios_instance_string(pdev, buf, + SMBIOS_ATTR_INSTANCE_SHOW); +} +static DEVICE_ATTR_RO(index); + +static struct attribute *smbios_attrs[] = { + &dev_attr_smbios_label.attr, + &dev_attr_index.attr, + NULL, +}; + +static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a, + int n) +{ + struct device *dev = kobj_to_dev(kobj); + struct pci_dev *pdev = to_pci_dev(dev); + + if (device_has_acpi_name(dev)) + return 0; + + if (!find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE)) + return 0; + + return a->mode; +} + +const struct attribute_group pci_dev_smbios_attr_group = { + .attrs = smbios_attrs, + .is_visible = smbios_attr_is_visible, +}; +#endif + +#ifdef CONFIG_ACPI +enum acpi_attr_enum { + ACPI_ATTR_LABEL_SHOW, + ACPI_ATTR_INDEX_SHOW, +}; + +static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf) +{ + int len; + + len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer, + obj->buffer.length, + UTF16_LITTLE_ENDIAN, + buf, PAGE_SIZE - 1); + buf[len++] = '\n'; + + return len; +} + +static int dsm_get_label(struct device *dev, char *buf, + enum acpi_attr_enum attr) +{ + acpi_handle handle = ACPI_HANDLE(dev); + union acpi_object *obj, *tmp; + int len = 0; + + if (!handle) + return -1; + + obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2, + DSM_PCI_DEVICE_NAME, NULL); + if (!obj) + return -1; + + tmp = obj->package.elements; + if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 && + tmp[0].type == ACPI_TYPE_INTEGER && + (tmp[1].type == ACPI_TYPE_STRING || + tmp[1].type == ACPI_TYPE_BUFFER)) { + /* + * The second string element is optional even when + * this _DSM is implemented; when not implemented, + * this entry must return a null string. + */ + if (attr == ACPI_ATTR_INDEX_SHOW) { + len = sysfs_emit(buf, "%llu\n", tmp->integer.value); + } else if (attr == ACPI_ATTR_LABEL_SHOW) { + if (tmp[1].type == ACPI_TYPE_STRING) + len = sysfs_emit(buf, "%s\n", + tmp[1].string.pointer); + else if (tmp[1].type == ACPI_TYPE_BUFFER) + len = dsm_label_utf16s_to_utf8s(tmp + 1, buf); + } + } + + ACPI_FREE(obj); + + return len > 0 ? len : -1; +} + +static ssize_t label_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW); +} +static DEVICE_ATTR_RO(label); + +static ssize_t acpi_index_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW); +} +static DEVICE_ATTR_RO(acpi_index); + +static struct attribute *acpi_attrs[] = { + &dev_attr_label.attr, + &dev_attr_acpi_index.attr, + NULL, +}; + +static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a, + int n) +{ + struct device *dev = kobj_to_dev(kobj); + + if (!device_has_acpi_name(dev)) + return 0; + + return a->mode; +} + +const struct attribute_group pci_dev_acpi_attr_group = { + .attrs = acpi_attrs, + .is_visible = acpi_attr_is_visible, +}; +#endif |