[SCSI] libfcoe: Add fcoe_sysfs

This patch adds a 'fcoe bus' infrastructure to the kernel
that is driven by changes to libfcoe which allow LLDs to
present FIP (FCoE Initialization Protocol) discovered
entities and their attributes to user space via sysfs.

This patch adds the following APIs-

fcoe_ctlr_device_add
fcoe_ctlr_device_delete
fcoe_fcf_device_add
fcoe_fcf_device_delete

They allow the LLD to expose the FCoE ENode Controller
and any discovered FCFs (Fibre Channel Forwarders, e.g.
FCoE switches) to the user. Each of these new devices
has their own bus_type so that they are grouped together
for easy lookup from a user space application. Each
new class has an attribute_group to expose attributes
for any created instances. The attributes are-

fcoe_ctlr_device
* fcf_dev_loss_tmo
* lesb_link_fail
* lesb_vlink_fail
* lesb_miss_fka
* lesb_symb_err
* lesb_err_block
* lesb_fcs_error

fcoe_fcf_device
* fabric_name
* switch_name
* priority
* selected
* fc_map
* vfid
* mac
* fka_peroid
* fabric_state
* dev_loss_tmo

A device loss infrastructre similar to the FC Transport's
is also added by this patch. It is nice to have so that a
link flapping adapter doesn't continually advance the count
used to identify the discovered FCF. FCFs will exist in a
"Disconnected" state until either the timer expires or the
FCF is rediscovered and becomes "Connected."

This patch generates a few checkpatch.pl WARNINGS that
I'm not sure what to do about. They're macros modeled
around the FC Transport attribute building macros, which
have the same 'feature' where the caller can ommit a cast
in the argument list and no cast occurs in the code. I'm
not sure how to keep the code condensed while keeping the
macros. Any advice would be appreciated.

Signed-off-by: Robert Love <[email protected]>
Tested-by: Ross Brattain <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: James Bottomley <[email protected]>

Author: Robert Love

Documentation/ABI/testing/sysfs-bus-fcoe

@@ -0,0 +1,77 @@
+What:		/sys/bus/fcoe/ctlr_X
+Date:		March 2012
+KernelVersion:	TBD
+Contact:	Robert Love <[email protected]>, [email protected]
+Description:	'FCoE Controller' instances on the fcoe bus
+Attributes:
+
+	fcf_dev_loss_tmo: Device loss timeout peroid (see below). Changing
+			  this value will change the dev_loss_tmo for all
+			  FCFs discovered by this controller.
+
+	lesb_link_fail:   Link Error Status Block (LESB) link failure count.
+
+	lesb_vlink_fail:  Link Error Status Block (LESB) virtual link
+			  failure count.
+
+	lesb_miss_fka:    Link Error Status Block (LESB) missed FCoE
+			  Initialization Protocol (FIP) Keep-Alives (FKA).
+
+	lesb_symb_err:    Link Error Status Block (LESB) symbolic error count.
+
+	lesb_err_block:   Link Error Status Block (LESB) block error count.
+
+	lesb_fcs_error:   Link Error Status Block (LESB) Fibre Channel
+			  Serivces error count.
+
+Notes: ctlr_X (global increment starting at 0)
+
+What:		/sys/bus/fcoe/fcf_X
+Date:		March 2012
+KernelVersion:	TBD
+Contact:	Robert Love <[email protected]>, [email protected]
+Description:	'FCoE FCF' instances on the fcoe bus. A FCF is a Fibre Channel
+		Forwarder, which is a FCoE switch that can accept FCoE
+		(Ethernet) packets, unpack them, and forward the embedded
+		Fibre Channel frames into a FC fabric. It can also take
+		outbound FC frames and pack them in Ethernet packets to
+		be sent to their destination on the Ethernet segment.
+Attributes:
+
+	fabric_name: Identifies the fabric that the FCF services.
+
+	switch_name: Identifies the FCF.
+
+	priority:    The switch's priority amongst other FCFs on the same
+		     fabric.
+
+	selected:    1 indicates that the switch has been selected for use;
+		     0 indicates that the swich will not be used.
+
+	fc_map:      The Fibre Channel MAP
+
+	vfid:	     The Virtual Fabric ID
+
+	mac:         The FCF's MAC address
+
+	fka_peroid:  The FIP Keep-Alive peroid
+
+	fabric_state: The internal kernel state
+		      "Unknown" - Initialization value
+		      "Disconnected" - No link to the FCF/fabric
+		      "Connected" - Host is connected to the FCF
+		      "Deleted" - FCF is being removed from the system
+
+	dev_loss_tmo: The device loss timeout peroid for this FCF.
+
+Notes: A device loss infrastructre similar to the FC Transport's
+       is present in fcoe_sysfs. It is nice to have so that a
+       link flapping adapter doesn't continually advance the count
+       used to identify the discovered FCF. FCFs will exist in a
+       "Disconnected" state until either the timer expires and the
+       FCF becomes "Deleted" or the FCF is rediscovered and becomes
+       "Connected."
+
+
+Users: The first user of this interface will be the fcoeadm application,
+       which is commonly packaged in the fcoe-utils package.

drivers/scsi/fcoe/Makefile

@@ -1,4 +1,4 @@
 obj-$(CONFIG_FCOE) += fcoe.o
 obj-$(CONFIG_LIBFCOE) += libfcoe.o
 
-libfcoe-objs := fcoe_ctlr.o fcoe_transport.o
+libfcoe-objs := fcoe_ctlr.o fcoe_transport.o fcoe_sysfs.o