1 files changed, 311 insertions, 0 deletions
diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c
new file mode 100644
index 000000000..cd84cf52a
--- /dev/null
+++ b/drivers/pci/pci-label.c
@@ -0,0 +1,311 @@
+// 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"
+
+#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;
+	int bus;
+	int devfn;
+
+	domain_nr = pci_domain_nr(pdev->bus);
+	bus = pdev->bus->number;
+	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 scnprintf(buf, PAGE_SIZE,
+							 "%d\n",
+							 donboard->instance);
+				else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
+					return scnprintf(buf, PAGE_SIZE,
+							 "%s\n",
+							 dmi->name);
+			}
+			return strlen(dmi->name);
+		}
+	}
+	return 0;
+}
+
+static umode_t smbios_instance_string_exist(struct kobject *kobj,
+					    struct attribute *attr, int n)
+{
+	struct device *dev;
+	struct pci_dev *pdev;
+
+	dev = kobj_to_dev(kobj);
+	pdev = to_pci_dev(dev);
+
+	return find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE) ?
+					   S_IRUGO : 0;
+}
+
+static ssize_t smbioslabel_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev;
+	pdev = to_pci_dev(dev);
+
+	return find_smbios_instance_string(pdev, buf,
+					   SMBIOS_ATTR_LABEL_SHOW);
+}
+
+static ssize_t smbiosinstance_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev;
+	pdev = to_pci_dev(dev);
+
+	return find_smbios_instance_string(pdev, buf,
+					   SMBIOS_ATTR_INSTANCE_SHOW);
+}
+
+static struct device_attribute smbios_attr_label = {
+	.attr = {.name = "label", .mode = 0444},
+	.show = smbioslabel_show,
+};
+
+static struct device_attribute smbios_attr_instance = {
+	.attr = {.name = "index", .mode = 0444},
+	.show = smbiosinstance_show,
+};
+
+static struct attribute *smbios_attributes[] = {
+	&smbios_attr_label.attr,
+	&smbios_attr_instance.attr,
+	NULL,
+};
+
+static const struct attribute_group smbios_attr_group = {
+	.attrs = smbios_attributes,
+	.is_visible = smbios_instance_string_exist,
+};
+
+static int pci_create_smbiosname_file(struct pci_dev *pdev)
+{
+	return sysfs_create_group(&pdev->dev.kobj, &smbios_attr_group);
+}
+
+static void pci_remove_smbiosname_file(struct pci_dev *pdev)
+{
+	sysfs_remove_group(&pdev->dev.kobj, &smbios_attr_group);
+}
+#else
+static inline int pci_create_smbiosname_file(struct pci_dev *pdev)
+{
+	return -1;
+}
+
+static inline void pci_remove_smbiosname_file(struct pci_dev *pdev)
+{
+}
+#endif
+
+#ifdef CONFIG_ACPI
+enum acpi_attr_enum {
+	ACPI_ATTR_LABEL_SHOW,
+	ACPI_ATTR_INDEX_SHOW,
+};
+
+static void 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';
+}
+
+static int dsm_get_label(struct device *dev, char *buf,
+			 enum acpi_attr_enum attr)
+{
+	acpi_handle handle;
+	union acpi_object *obj, *tmp;
+	int len = -1;
+
+	handle = ACPI_HANDLE(dev);
+	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) {
+			scnprintf(buf, PAGE_SIZE, "%llu\n", tmp->integer.value);
+		} else if (attr == ACPI_ATTR_LABEL_SHOW) {
+			if (tmp[1].type == ACPI_TYPE_STRING)
+				scnprintf(buf, PAGE_SIZE, "%s\n",
+					  tmp[1].string.pointer);
+			else if (tmp[1].type == ACPI_TYPE_BUFFER)
+				dsm_label_utf16s_to_utf8s(tmp + 1, buf);
+		}
+		len = strlen(buf) > 0 ? strlen(buf) : -1;
+	}
+
+	ACPI_FREE(obj);
+
+	return len;
+}
+
+static bool device_has_dsm(struct device *dev)
+{
+	acpi_handle handle;
+
+	handle = ACPI_HANDLE(dev);
+	if (!handle)
+		return false;
+
+	return !!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
+				1 << DSM_PCI_DEVICE_NAME);
+}
+
+static umode_t acpi_index_string_exist(struct kobject *kobj,
+				       struct attribute *attr, int n)
+{
+	struct device *dev;
+
+	dev = kobj_to_dev(kobj);
+
+	if (device_has_dsm(dev))
+		return S_IRUGO;
+
+	return 0;
+}
+
+static ssize_t acpilabel_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
+}
+
+static ssize_t acpiindex_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
+}
+
+static struct device_attribute acpi_attr_label = {
+	.attr = {.name = "label", .mode = 0444},
+	.show = acpilabel_show,
+};
+
+static struct device_attribute acpi_attr_index = {
+	.attr = {.name = "acpi_index", .mode = 0444},
+	.show = acpiindex_show,
+};
+
+static struct attribute *acpi_attributes[] = {
+	&acpi_attr_label.attr,
+	&acpi_attr_index.attr,
+	NULL,
+};
+
+static const struct attribute_group acpi_attr_group = {
+	.attrs = acpi_attributes,
+	.is_visible = acpi_index_string_exist,
+};
+
+static int pci_create_acpi_index_label_files(struct pci_dev *pdev)
+{
+	return sysfs_create_group(&pdev->dev.kobj, &acpi_attr_group);
+}
+
+static int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
+{
+	sysfs_remove_group(&pdev->dev.kobj, &acpi_attr_group);
+	return 0;
+}
+#else
+static inline int pci_create_acpi_index_label_files(struct pci_dev *pdev)
+{
+	return -1;
+}
+
+static inline int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
+{
+	return -1;
+}
+
+static inline bool device_has_dsm(struct device *dev)
+{
+	return false;
+}
+#endif
+
+void pci_create_firmware_label_files(struct pci_dev *pdev)
+{
+	if (device_has_dsm(&pdev->dev))
+		pci_create_acpi_index_label_files(pdev);
+	else
+		pci_create_smbiosname_file(pdev);
+}
+
+void pci_remove_firmware_label_files(struct pci_dev *pdev)
+{
+	if (device_has_dsm(&pdev->dev))
+		pci_remove_acpi_index_label_files(pdev);
+	else
+		pci_remove_smbiosname_file(pdev);
+}