scsi: target: core: Add configurable IEEE Company ID attribute

Implement an attribute which provides a way to set a company specific WWN
in configfs via:

  target/core/$backstore/$name/wwn/company_id

The Open Fabrics Alliance ID 001405h remains the default.

Link: https://lore.kernel.org/r/20210420185920.42431-3-s.samoylenko@yadro.com
Signed-off-by: Sergey Samoylenko <s.samoylenko@yadro.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_configfs.c

@@ -1479,6 +1479,54 @@ static ssize_t target_wwn_revision_store(struct config_item *item,
 	return count;
 }
 
+static ssize_t
+target_wwn_company_id_show(struct config_item *item,
+				char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%#08x\n",
+			to_t10_wwn(item)->company_id);
+}
+
+static ssize_t
+target_wwn_company_id_store(struct config_item *item,
+				 const char *page, size_t count)
+{
+	struct t10_wwn *t10_wwn = to_t10_wwn(item);
+	struct se_device *dev = t10_wwn->t10_dev;
+	u32 val;
+	int ret;
+
+	/*
+	 * The IEEE COMPANY_ID field should contain a 24-bit canonical
+	 * form OUI assigned by the IEEE.
+	 */
+	ret = kstrtou32(page, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val >= 0x1000000)
+		return -EOVERFLOW;
+
+	/*
+	 * Check to see if any active exports exist. If they do exist, fail
+	 * here as changing this information on the fly (underneath the
+	 * initiator side OS dependent multipath code) could cause negative
+	 * effects.
+	 */
+	if (dev->export_count) {
+		pr_err("Unable to set Company ID while %u exports exist\n",
+		       dev->export_count);
+		return -EINVAL;
+	}
+
+	t10_wwn->company_id = val;
+
+	pr_debug("Target_Core_ConfigFS: Set IEEE Company ID: %#08x\n",
+		 t10_wwn->company_id);
+
+	return count;
+}
+
 /*
  * VPD page 0x80 Unit serial
  */
@@ -1625,6 +1673,7 @@ DEF_DEV_WWN_ASSOC_SHOW(vpd_assoc_scsi_target_device, 0x20);
 CONFIGFS_ATTR(target_wwn_, vendor_id);
 CONFIGFS_ATTR(target_wwn_, product_id);
 CONFIGFS_ATTR(target_wwn_, revision);
+CONFIGFS_ATTR(target_wwn_, company_id);
 CONFIGFS_ATTR(target_wwn_, vpd_unit_serial);
 CONFIGFS_ATTR_RO(target_wwn_, vpd_protocol_identifier);
 CONFIGFS_ATTR_RO(target_wwn_, vpd_assoc_logical_unit);
@@ -1635,6 +1684,7 @@ static struct configfs_attribute *target_core_dev_wwn_attrs[] = {
 	&target_wwn_attr_vendor_id,
 	&target_wwn_attr_product_id,
 	&target_wwn_attr_revision,
+	&target_wwn_attr_company_id,
 	&target_wwn_attr_vpd_unit_serial,
 	&target_wwn_attr_vpd_protocol_identifier,
 	&target_wwn_attr_vpd_assoc_logical_unit,

drivers/target/target_core_device.c

@@ -773,6 +773,11 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
 	spin_lock_init(&dev->t10_alua.lba_map_lock);
 
 	dev->t10_wwn.t10_dev = dev;
+	/*
+	 * Use OpenFabrics IEEE Company ID: 00 14 05
+	 */
+	dev->t10_wwn.company_id = 0x001405;
+
 	dev->t10_alua.t10_dev = dev;
 
 	dev->dev_attrib.da_dev = dev;

drivers/target/target_core_spc.c

@@ -136,20 +136,20 @@ void spc_gen_naa_6h_vendor_specific(struct se_device *dev,
 				    unsigned char *buf)
 {
 	unsigned char *p = &dev->t10_wwn.unit_serial[0];
+	u32 company_id = dev->t10_wwn.company_id;
 	int cnt, off = 0;
 	bool next = true;
 
 	/*
 	 * Start NAA IEEE Registered Extended Identifier/Designator
 	 */
-	buf[off++] = 0x6 << 4;
+	buf[off] = 0x6 << 4;
 
-	/*
-	 * Use OpenFabrics IEEE Company ID: 00 14 05
-	 */
-	buf[off++] = 0x01;
-	buf[off++] = 0x40;
-	buf[off] = (0x5 << 4);
+	/* IEEE COMPANY_ID */
+	buf[off++] |= (company_id >> 20) & 0xf;
+	buf[off++] = (company_id >> 12) & 0xff;
+	buf[off++] = (company_id >> 4) & 0xff;
+	buf[off] = (company_id & 0xf) << 4;
 
 	/*
 	 * Generate up to 36 bits of VENDOR SPECIFIC IDENTIFIER starting on

include/target/target_core_base.h

@@ -326,6 +326,7 @@ struct t10_wwn {
 	char model[INQUIRY_MODEL_LEN + 1];
 	char revision[INQUIRY_REVISION_LEN + 1];
 	char unit_serial[INQUIRY_VPD_SERIAL_LEN];
+	u32 company_id;
 	spinlock_t t10_vpd_lock;
 	struct se_device *t10_dev;
 	struct config_group t10_wwn_group;