ibft: Expose iBFT acpi header via sysfs

Some ethernet adapter vendors are supplying products which support optional
(payed license) features. On some adapters this includes a hardware iscsi
initiator. The same adapters in a normal (no extra licenses) mode of
operation can be used as a software iscsi initiator. In addition, software
iscsi boot initiators are becoming a standard part of many vendors uefi
implementations. This is creating difficulties during early boot/install
determining the proper configuration method for these adapters when they
are used as a boot device.

The attached patch creates sysfs entries to expose information from the
acpi header of the ibft table. This information allows for a method to
easily determining if an ibft table was created by a ethernet card's
firmware or the system uefi/bios. In the case of a hardware initiator this
information in combination with the pci vendor and device id can be used
to ascertain any vendor specific behaviors that need to be accommodated.

Reviewed-by: Lee Duncan <[e-mail]>
Signed-off-by: David Bond <[e-mail]>
Signed-off-by: Konrad Rzeszutek Wilk <[e-mail]>

Documentation/ABI/testing/sysfs-ibft

···
 Description:	The /sys/firmware/ibft/ethernetX directory will contain
 		files that expose the iSCSI Boot Firmware Table NIC data.
 		Usually this contains the IP address, MAC, and gateway of the NIC.
+
+What:		/sys/firmware/ibft/acpi_header
+Date:		March 2016
+Contact:	David Bond <[e-mail]>
+Description:	The /sys/firmware/ibft/acpi_header directory will contain files
+		that expose the SIGNATURE, OEM_ID, and OEM_TABLE_ID fields of the
+		acpi table header of the iBFT structure.  This will allow for
+		identification of the creator of the table which is useful in
+		determining quirks associated with some adapters when used in
+		hardware vs software iscsi initiator mode.

drivers/firmware/iscsi_ibft.c

···
 	return str - buf;
 }
 
+static ssize_t ibft_attr_show_acpitbl(void *data, int type, char *buf)
+{
+	struct ibft_kobject *entry = data;
+	char *str = buf;
+
+	switch (type) {
+	case ISCSI_BOOT_ACPITBL_SIGNATURE:
+		str += sprintf_string(str, ACPI_NAME_SIZE,
+				      entry->header->header.signature);
+		break;
+	case ISCSI_BOOT_ACPITBL_OEM_ID:
+		str += sprintf_string(str, ACPI_OEM_ID_SIZE,
+				      entry->header->header.oem_id);
+		break;
+	case ISCSI_BOOT_ACPITBL_OEM_TABLE_ID:
+		str += sprintf_string(str, ACPI_OEM_TABLE_ID_SIZE,
+				      entry->header->header.oem_table_id);
+		break;
+	default:
+		break;
+	}
+
+	return str - buf;
+}
+
 static int __init ibft_check_device(void)
 {
 	int len;
···
 	return rc;
 }
 
+static umode_t __init ibft_check_acpitbl_for(void *data, int type)
+{
+
+	umode_t rc = 0;
+
+	switch (type) {
+	case ISCSI_BOOT_ACPITBL_SIGNATURE:
+	case ISCSI_BOOT_ACPITBL_OEM_ID:
+	case ISCSI_BOOT_ACPITBL_OEM_TABLE_ID:
+		rc = S_IRUGO;
+		break;
+	default:
+		break;
+	}
+
+	return rc;
+}
+
 static void ibft_kobj_release(void *data)
 {
 	kfree(data);
···
 static int __init ibft_register_kobjects(struct acpi_table_ibft *header)
 {
 	struct ibft_control *control = NULL;
+	struct iscsi_boot_kobj *boot_kobj;
+	struct ibft_kobject *ibft_kobj;
 	void *ptr, *end;
 	int rc = 0;
 	u16 offset;
···
 				break;
 		}
 	}
+	if (rc)
+		return rc;
+
+	ibft_kobj = kzalloc(sizeof(*ibft_kobj), GFP_KERNEL);
+	if (!ibft_kobj)
+		return -ENOMEM;
+
+	ibft_kobj->header = header;
+	ibft_kobj->hdr = NULL; /*for ibft_unregister*/
+
+	boot_kobj = iscsi_boot_create_acpitbl(boot_kset, 0,
+					ibft_kobj,
+					ibft_attr_show_acpitbl,
+					ibft_check_acpitbl_for,
+					ibft_kobj_release);
+	if (!boot_kobj)  {
+		kfree(ibft_kobj);
+		rc = -ENOMEM;
+	}
 
 	return rc;
 }
···
 	list_for_each_entry_safe(boot_kobj, tmp_kobj,
 				 &boot_kset->kobj_list, list) {
 		ibft_kobj = boot_kobj->data;
-		if (ibft_kobj->hdr->id == id_nic)
+		if (ibft_kobj->hdr && ibft_kobj->hdr->id == id_nic)
 			sysfs_remove_link(&boot_kobj->kobj, "device");
 	};
 }

drivers/scsi/iscsi_boot_sysfs.c

···
 	.is_visible = iscsi_boot_ini_attr_is_visible,
 };
 
+/* iBFT ACPI Table attributes */
+iscsi_boot_rd_attr(acpitbl_signature, signature, ISCSI_BOOT_ACPITBL_SIGNATURE);
+iscsi_boot_rd_attr(acpitbl_oem_id, oem_id, ISCSI_BOOT_ACPITBL_OEM_ID);
+iscsi_boot_rd_attr(acpitbl_oem_table_id, oem_table_id,
+		   ISCSI_BOOT_ACPITBL_OEM_TABLE_ID);
+
+static struct attribute *acpitbl_attrs[] = {
+	&iscsi_boot_attr_acpitbl_signature.attr,
+	&iscsi_boot_attr_acpitbl_oem_id.attr,
+	&iscsi_boot_attr_acpitbl_oem_table_id.attr,
+	NULL
+};
+
+static umode_t iscsi_boot_acpitbl_attr_is_visible(struct kobject *kobj,
+					     struct attribute *attr, int i)
+{
+	struct iscsi_boot_kobj *boot_kobj =
+			container_of(kobj, struct iscsi_boot_kobj, kobj);
+
+	if (attr ==  &iscsi_boot_attr_acpitbl_signature.attr)
+		return boot_kobj->is_visible(boot_kobj->data,
+					     ISCSI_BOOT_ACPITBL_SIGNATURE);
+	if (attr ==  &iscsi_boot_attr_acpitbl_oem_id.attr)
+		return boot_kobj->is_visible(boot_kobj->data,
+					     ISCSI_BOOT_ACPITBL_OEM_ID);
+	if (attr ==  &iscsi_boot_attr_acpitbl_oem_table_id.attr)
+		return boot_kobj->is_visible(boot_kobj->data,
+					     ISCSI_BOOT_ACPITBL_OEM_TABLE_ID);
+	return 0;
+}
+
+static struct attribute_group iscsi_boot_acpitbl_attr_group = {
+	.attrs = acpitbl_attrs,
+	.is_visible = iscsi_boot_acpitbl_attr_is_visible,
+};
+
 static struct iscsi_boot_kobj *
 iscsi_boot_create_kobj(struct iscsi_boot_kset *boot_kset,
 		       struct attribute_group *attr_group,
···
 				      is_visible, release);
 }
 EXPORT_SYMBOL_GPL(iscsi_boot_create_ethernet);
+
+/**
+ * iscsi_boot_create_acpitbl() - create boot acpi table sysfs dir
+ * @boot_kset: boot kset
+ * @index: not used
+ * @data: driver specific data
+ * @show: attr show function
+ * @is_visible: attr visibility function
+ * @release: release function
+ *
+ * Note: The boot sysfs lib will free the data passed in for the caller
+ * when all refs to the acpitbl kobject have been released.
+ */
+struct iscsi_boot_kobj *
+iscsi_boot_create_acpitbl(struct iscsi_boot_kset *boot_kset, int index,
+			   void *data,
+			   ssize_t (*show)(void *data, int type, char *buf),
+			   umode_t (*is_visible)(void *data, int type),
+			   void (*release)(void *data))
+{
+	return iscsi_boot_create_kobj(boot_kset,
+				      &iscsi_boot_acpitbl_attr_group,
+				      "acpi_header", index, data, show,
+				      is_visible, release);
+}
+EXPORT_SYMBOL_GPL(iscsi_boot_create_acpitbl);
 
 /**
  * iscsi_boot_create_kset() - creates root sysfs tree

include/linux/iscsi_boot_sysfs.h

···
 	ISCSI_BOOT_INI_END_MARKER,
 };
 
+enum iscsi_boot_acpitbl_properties_enum {
+	ISCSI_BOOT_ACPITBL_SIGNATURE,
+	ISCSI_BOOT_ACPITBL_OEM_ID,
+	ISCSI_BOOT_ACPITBL_OEM_TABLE_ID,
+};
+
 struct attribute_group;
 
 struct iscsi_boot_kobj {
···
 			 ssize_t (*show) (void *data, int type, char *buf),
 			 umode_t (*is_visible) (void *data, int type),
 			 void (*release) (void *data));
+
+struct iscsi_boot_kobj *
+iscsi_boot_create_acpitbl(struct iscsi_boot_kset *boot_kset, int index,
+			  void *data,
+			  ssize_t (*show)(void *data, int type, char *buf),
+			  umode_t (*is_visible)(void *data, int type),
+			  void (*release)(void *data));
 
 struct iscsi_boot_kset *iscsi_boot_create_kset(const char *set_name);
 struct iscsi_boot_kset *iscsi_boot_create_host_kset(unsigned int hostno);