firewire: fw-sbp2: implement sysfs ieee1394_id

The attribute /sys/bus/scsi/devices/*:*:*:*/ieee1394_id, as generated by
the old sbp2 driver, is typically used to create persistently named
links in /dev/disk/by-id.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Kristian Høgsberg <krh@redhat.com>

2 files changed, 54 insertions, 0 deletions

diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 0ba9d64ccf4c..af1723eae4ba 100644
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -99,6 +99,7 @@ fw_unit(struct device *dev)
 #define CSR_DEPENDENT_INFO      0x14
 #define CSR_MODEL               0x17
 #define CSR_INSTANCE            0x18
+#define CSR_DIRECTORY_ID        0x20
 
 #define SBP2_COMMAND_SET_SPECIFIER      0x38
 #define SBP2_COMMAND_SET                0x39
diff --git a/drivers/firewire/fw-sbp2.c b/drivers/firewire/fw-sbp2.c
index 68300414e5f4..a98d3915e26f 100644
--- a/drivers/firewire/fw-sbp2.c
+++ b/drivers/firewire/fw-sbp2.c
@@ -1108,6 +1108,58 @@ static int sbp2_scsi_abort(struct scsi_cmnd *cmd)
         return SUCCESS;
 }
 
+/*
+ * Format of /sys/bus/scsi/devices/.../ieee1394_id:
+ * u64 EUI-64 : u24 directory_ID : u16 LUN  (all printed in hexadecimal)
+ *
+ * This is the concatenation of target port identifier and logical unit
+ * identifier as per SAM-2...SAM-4 annex A.
+ */
+static ssize_t
+sbp2_sysfs_ieee1394_id_show(struct device *dev, struct device_attribute *attr,
+                            char *buf)
+{
+        struct scsi_device *sdev = to_scsi_device(dev);
+        struct sbp2_device *sd;
+        struct fw_unit *unit;
+        struct fw_device *device;
+        u32 directory_id;
+        struct fw_csr_iterator ci;
+        int key, value, lun;
+
+        if (!sdev)
+                return 0;
+        sd = (struct sbp2_device *)sdev->host->hostdata;
+        unit = sd->unit;
+        device = fw_device(unit->device.parent);
+
+        /* implicit directory ID */
+        directory_id = ((unit->directory - device->config_rom) * 4
+                        + CSR_CONFIG_ROM) & 0xffffff;
+
+        /* explicit directory ID, overrides implicit ID if present */
+        fw_csr_iterator_init(&ci, unit->directory);
+        while (fw_csr_iterator_next(&ci, &key, &value))
+                if (key == CSR_DIRECTORY_ID) {
+                        directory_id = value;
+                        break;
+                }
+
+        /* FIXME: Make this work for multi-lun devices. */
+        lun = 0;
+
+        return sprintf(buf, "%08x%08x:%06x:%04x\n",
+                        device->config_rom[3], device->config_rom[4],
+                        directory_id, lun);
+}
+
+static DEVICE_ATTR(ieee1394_id, S_IRUGO, sbp2_sysfs_ieee1394_id_show, NULL);
+
+static struct device_attribute *sbp2_scsi_sysfs_attrs[] = {
+        &dev_attr_ieee1394_id,
+        NULL
+};
+
 static struct scsi_host_template scsi_driver_template = {
         .module                 = THIS_MODULE,
         .name                   = "SBP-2 IEEE-1394",
@@ -1121,6 +1173,7 @@ static struct scsi_host_template scsi_driver_template = {
         .use_clustering         = ENABLE_CLUSTERING,
         .cmd_per_lun            = 1,
         .can_queue              = 1,
+        .sdev_attrs             = sbp2_scsi_sysfs_attrs,
 };
 
 MODULE_AUTHOR("Kristian Hoegsberg <krh@bitplanet.net>");