[SCSI] Add Documentation and integrate into docbook build

Add Documentation/DocBook/scsi_midlayer.tmpl, add to Makefile, and update
lots of kerneldoc comments in drivers/scsi/*.

Updated with comments from Stefan Richter, Stephen M. Cameron,
 James Bottomley and Randy Dunlap.

Signed-off-by: Rob Landley <rob@landley.net>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

17 files changed, 821 insertions, 289 deletions

diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index 4953bc25872..c6c5e59daac 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -11,7 +11,7 @@ DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \
 	    procfs-guide.xml writing_usb_driver.xml \
 	    kernel-api.xml filesystems.xml lsm.xml usb.xml \
 	    gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
-	    genericirq.xml s390-drivers.xml uio-howto.xml
+	    genericirq.xml s390-drivers.xml uio-howto.xml scsi_midlayer.xml
 
 ###
 # The build process is as follows (targets):
diff --git a/Documentation/DocBook/scsi_midlayer.tmpl b/Documentation/DocBook/scsi_midlayer.tmpl
new file mode 100644
index 00000000000..6255930216b
--- /dev/null
+++ b/Documentation/DocBook/scsi_midlayer.tmpl
@@ -0,0 +1,409 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
+
+<book id="scsimid">
+  <bookinfo>
+    <title>SCSI Mid Layer Guide</title>
+
+    <authorgroup>
+      <author>
+        <firstname>James</firstname>
+        <surname>Bottomley</surname>
+        <affiliation>
+          <address>
+            <email>James.Bottomley@steeleye.com</email>
+          </address>
+        </affiliation>
+      </author>
+
+      <author>
+        <firstname>Rob</firstname>
+        <surname>Landley</surname>
+        <affiliation>
+          <address>
+            <email>rob@landley.net</email>
+          </address>
+        </affiliation>
+      </author>
+
+    </authorgroup>
+
+    <copyright>
+      <year>2007</year>
+      <holder>Linux Foundation</holder>
+    </copyright>
+
+    <legalnotice>
+      <para>
+        This documentation is free software; you can redistribute
+        it and/or modify it under the terms of the GNU General Public
+        License version 2.
+      </para>
+
+      <para>
+        This program is distributed in the hope that it will be
+        useful, but WITHOUT ANY WARRANTY; without even the implied
+        warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+        For more details see the file COPYING in the source
+        distribution of Linux.
+      </para>
+    </legalnotice>
+  </bookinfo>
+
+  <toc></toc>
+
+  <chapter id="intro">
+    <title>Introduction</title>
+    <sect1 id="protocol_vs_bus">
+      <title>Protocol vs bus</title>
+      <para>
+        Once upon a time, the Small Computer Systems Interface defined both
+        a parallel I/O bus and a data protocol to connect a wide variety of
+        peripherals (disk drives, tape drives, modems, printers, scanners,
+        optical drives, test equipment, and medical devices) to a host
+        computer.
+      </para>
+      <para>
+        Although the old parallel (fast/wide/ultra) SCSI bus has largely
+        fallen out of use, the SCSI command set is more widely used than ever
+        to communicate with devices over a number of different busses.
+      </para>
+      <para>
+        The <ulink url='http://www.t10.org/scsi-3.htm'>SCSI protocol</ulink>
+        is a big-endian peer-to-peer packet based protocol.  SCSI commands
+        are 6, 10, 12, or 16 bytes long, often followed by an associated data
+        payload.
+      </para>
+      <para>
+        SCSI commands can be transported over just about any kind of bus, and
+        are the default protocol for storage devices attached to USB, SATA,
+        SAS, Fibre Channel, FireWire, and ATAPI devices.  SCSI packets are
+        also commonly exchanged over Infiniband,
+        <ulink url='http://i2o.shadowconnect.com/faq.php'>I20</ulink>, TCP/IP
+        (<ulink url='http://en.wikipedia.org/wiki/ISCSI'>iSCSI</ulink>), even
+        <ulink url='http://cyberelk.net/tim/parport/parscsi.html'>Parallel
+        ports</ulink>.
+      </para>
+    </sect1>
+    <sect1 id="subsystem_design">
+      <title>Design of the Linux SCSI subsystem</title>
+      <para>
+        The SCSI subsystem uses a three layer design, with upper, mid, and low
+        layers.  Every operation involving the SCSI subsystem (such as reading
+        a sector from a disk) uses one driver at each of the 3 levels: one
+        upper layer driver, one lower layer driver, and the scsi midlayer.
+      </para>
+      <para>
+        The SCSI upper layer provides the interface between userspace and the
+        kernel, in the form of block and char device nodes for I/O and
+        ioctl().  The SCSI lower layer contains drivers for specific hardware
+        devices.
+      </para>
+      <para>
+        In between is the SCSI mid-layer, analogous to a network routing
+        layer such as the IPv4 stack.  The SCSI mid-layer routes a packet
+        based data protocol between the upper layer's /dev nodes and the
+        corresponding devices in the lower layer.  It manages command queues,
+        provides error handling and power management functions, and responds
+        to ioctl() requests.
+      </para>
+    </sect1>
+  </chapter>
+
+  <chapter id="upper_layer">
+    <title>SCSI upper layer</title>
+    <para>
+      The upper layer supports the user-kernel interface by providing
+      device nodes.
+    </para>
+    <sect1 id="sd">
+      <title>sd (SCSI Disk)</title>
+      <para>sd (sd_mod.o)</para>
+<!-- !Idrivers/scsi/sd.c -->
+    </sect1>
+    <sect1 id="sr">
+      <title>sr (SCSI CD-ROM)</title>
+      <para>sr (sr_mod.o)</para>
+    </sect1>
+    <sect1 id="st">
+      <title>st (SCSI Tape)</title>
+      <para>st (st.o)</para>
+    </sect1>
+    <sect1 id="sg">
+      <title>sg (SCSI Generic)</title>
+      <para>sg (sg.o)</para>
+    </sect1>
+    <sect1 id="ch">
+      <title>ch (SCSI Media Changer)</title>
+      <para>ch (ch.c)</para>
+    </sect1>
+  </chapter>
+
+  <chapter id="mid_layer">
+    <title>SCSI mid layer</title>
+
+    <sect1 id="midlayer_implementation">
+      <title>SCSI midlayer implementation</title>
+      <sect2 id="scsi_device.h">
+        <title>include/scsi/scsi_device.h</title>
+        <para>
+        </para>
+!Iinclude/scsi/scsi_device.h
+      </sect2>
+
+      <sect2 id="scsi.c">
+        <title>drivers/scsi/scsi.c</title>
+        <para>Main file for the scsi midlayer.</para>
+!Edrivers/scsi/scsi.c
+      </sect2>
+      <sect2 id="scsicam.c">
+        <title>drivers/scsi/scsicam.c</title>
+        <para>
+          <ulink url='http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf'>SCSI
+          Common Access Method</ulink> support functions, for use with
+          HDIO_GETGEO, etc.
+        </para>
+!Edrivers/scsi/scsicam.c
+      </sect2>
+      <sect2 id="scsi_error.c">
+        <title>drivers/scsi/scsi_error.c</title>
+        <para>Common SCSI error/timeout handling routines.</para>
+!Edrivers/scsi/scsi_error.c
+      </sect2>
+      <sect2 id="scsi_devinfo.c">
+        <title>drivers/scsi/scsi_devinfo.c</title>
+        <para>
+          Manage scsi_dev_info_list, which tracks blacklisted and whitelisted
+          devices.
+        </para>
+!Idrivers/scsi/scsi_devinfo.c
+      </sect2>
+      <sect2 id="scsi_ioctl.c">
+        <title>drivers/scsi/scsi_ioctl.c</title>
+        <para>
+          Handle ioctl() calls for scsi devices.
+        </para>
+!Edrivers/scsi/scsi_ioctl.c
+      </sect2>
+      <sect2 id="scsi_lib.c">
+        <title>drivers/scsi/scsi_lib.c</title>
+        <para>
+          SCSI queuing library.
+        </para>
+!Edrivers/scsi/scsi_lib.c
+      </sect2>
+      <sect2 id="scsi_lib_dma.c">
+        <title>drivers/scsi/scsi_lib_dma.c</title>
+        <para>
+          SCSI library functions depending on DMA
+          (map and unmap scatter-gather lists).
+        </para>
+!Edrivers/scsi/scsi_lib_dma.c
+      </sect2>
+      <sect2 id="scsi_module.c">
+        <title>drivers/scsi/scsi_module.c</title>
+        <para>
+          The file drivers/scsi/scsi_module.c contains legacy support for
+          old-style host templates.  It should never be used by any new driver.
+        </para>
+      </sect2>
+      <sect2 id="scsi_proc.c">
+        <title>drivers/scsi/scsi_proc.c</title>
+        <para>
+          The functions in this file provide an interface between
+          the PROC file system and the SCSI device drivers
+          It is mainly used for debugging, statistics and to pass
+          information directly to the lowlevel driver.
+
+          I.E. plumbing to manage /proc/scsi/*
+        </para>
+!Idrivers/scsi/scsi_proc.c
+      </sect2>
+      <sect2 id="scsi_netlink.c">
+        <title>drivers/scsi/scsi_netlink.c</title>
+        <para>
+          Infrastructure to provide async events from transports to userspace
+          via netlink, using a single NETLINK_SCSITRANSPORT protocol for all
+          transports.
+
+          See <ulink url='http://marc.info/?l=linux-scsi&amp;m=115507374832500&amp;w=2'>the
+          original patch submission</ulink> for more details.
+        </para>
+!Idrivers/scsi/scsi_netlink.c
+      </sect2>
+      <sect2 id="scsi_scan.c">
+        <title>drivers/scsi/scsi_scan.c</title>
+        <para>
+          Scan a host to determine which (if any) devices are attached.
+
+          The general scanning/probing algorithm is as follows, exceptions are
+          made to it depending on device specific flags, compilation options,
+          and global variable (boot or module load time) settings.
+
+          A specific LUN is scanned via an INQUIRY command; if the LUN has a
+          device attached, a scsi_device is allocated and setup for it.
+
+          For every id of every channel on the given host, start by scanning
+          LUN 0.  Skip hosts that don't respond at all to a scan of LUN 0.
+          Otherwise, if LUN 0 has a device attached, allocate and setup a
+          scsi_device for it.  If target is SCSI-3 or up, issue a REPORT LUN,
+          and scan all of the LUNs returned by the REPORT LUN; else,
+          sequentially scan LUNs up until some maximum is reached, or a LUN is
+          seen that cannot have a device attached to it.
+        </para>
+!Idrivers/scsi/scsi_scan.c
+      </sect2>
+      <sect2 id="scsi_sysctl.c">
+        <title>drivers/scsi/scsi_sysctl.c</title>
+        <para>
+          Set up the sysctl entry: "/dev/scsi/logging_level"
+          (DEV_SCSI_LOGGING_LEVEL) which sets/returns scsi_logging_level.
+        </para>
+      </sect2>
+      <sect2 id="scsi_sysfs.c">
+        <title>drivers/scsi/scsi_sysfs.c</title>
+        <para>
+          SCSI sysfs interface routines.
+        </para>
+!Edrivers/scsi/scsi_sysfs.c
+      </sect2>
+      <sect2 id="hosts.c">
+        <title>drivers/scsi/hosts.c</title>
+        <para>
+          mid to lowlevel SCSI driver interface
+        </para>
+!Edrivers/scsi/hosts.c
+      </sect2>
+      <sect2 id="constants.c">
+        <title>drivers/scsi/constants.c</title>
+        <para>
+          mid to lowlevel SCSI driver interface
+        </para>
+!Edrivers/scsi/constants.c
+      </sect2>
+    </sect1>
+
+    <sect1 id="Transport_classes">
+      <title>Transport classes</title>
+      <para>
+        Transport classes are service libraries for drivers in the scsi
+        lower layer, which expose transport attributes in sysfs.
+      </para>
+      <sect2 id="Fibre_Channel_transport">
+        <title>Fibre Channel transport</title>
+        <para>
+          The file drivers/scsi/scsi_transport_fc.c defines transport attributes
+          for Fibre Channel.
+        </para>
+!Edrivers/scsi/scsi_transport_fc.c
+      </sect2>
+      <sect2 id="iSCSI_transport">
+        <title>iSCSI transport class</title>
+        <para>
+          The file drivers/scsi/scsi_transport_iscsi.c defines transport
+          attributes for the iSCSI class, which sends SCSI packets over TCP/IP
+          connections.
+        </para>
+!Edrivers/scsi/scsi_transport_iscsi.c
+      </sect2>
+      <sect2 id="SAS_transport">
+        <title>Serial Attached SCSI (SAS) transport class</title>
+        <para>
+          The file drivers/scsi/scsi_transport_sas.c defines transport
+          attributes for Serial Attached SCSI, a variant of SATA aimed at
+          large high-end systems.
+        </para>
+        <para>
+          The SAS transport class contains common code to deal with SAS HBAs,
+          an aproximated representation of SAS topologies in the driver model,
+          and various sysfs attributes to expose these topologies and managment
+          interfaces to userspace.
+        </para>
+        <para>
+          In addition to the basic SCSI core objects this transport class
+          introduces two additional intermediate objects:  The SAS PHY
+          as represented by struct sas_phy defines an "outgoing" PHY on
+          a SAS HBA or Expander, and the SAS remote PHY represented by
+          struct sas_rphy defines an "incoming" PHY on a SAS Expander or
+          end device.  Note that this is purely a software concept, the
+          underlying hardware for a PHY and a remote PHY is the exactly
+          the same.
+        </para>
+        <para>
+          There is no concept of a SAS port in this code, users can see
+          what PHYs form a wide port based on the port_identifier attribute,
+          which is the same for all PHYs in a port.
+        </para>
+!Edrivers/scsi/scsi_transport_sas.c
+      </sect2>
+      <sect2 id="SATA_transport">
+        <title>SATA transport class</title>
+        <para>
+          The SATA transport is handled by libata, which has its own book of
+          documentation in this directory.
+        </para>
+      </sect2>
+      <sect2 id="SPI_transport">
+        <title>Parallel SCSI (SPI) transport class</title>
+        <para>
+          The file drivers/scsi/scsi_transport_spi.c defines transport
+          attributes for traditional (fast/wide/ultra) SCSI busses.
+        </para>
+!Edrivers/scsi/scsi_transport_spi.c
+      </sect2>
+      <sect2 id="SRP_transport">
+        <title>SCSI RDMA (SRP) transport class</title>
+        <para>
+          The file drivers/scsi/scsi_transport_srp.c defines transport
+          attributes for SCSI over Remote Direct Memory Access.
+        </para>
+!Edrivers/scsi/scsi_transport_srp.c
+      </sect2>
+    </sect1>
+
+  </chapter>
+
+  <chapter id="lower_layer">
+    <title>SCSI lower layer</title>
+    <sect1 id="hba_drivers">
+      <title>Host Bus Adapter transport types</title>
+      <para>
+        Many modern device controllers use the SCSI command set as a protocol to
+        communicate with their devices through many different types of physical
+        connections.
+      </para>
+      <para>
+        In SCSI language a bus capable of carrying SCSI commands is
+        called a "transport", and a controller connecting to such a bus is
+        called a "host bus adapter" (HBA).
+      </para>
+      <sect2 id="scsi_debug.c">
+        <title>Debug transport</title>
+        <para>
+          The file drivers/scsi/scsi_debug.c simulates a host adapter with a
+          variable number of disks (or disk like devices) attached, sharing a
+          common amount of RAM.  Does a lot of checking to make sure that we are
+          not getting blocks mixed up, and panics the kernel if anything out of
+          the ordinary is seen.
+        </para>
+        <para>
+          To be more realistic, the simulated devices have the transport
+          attributes of SAS disks.
+        </para>
+        <para>
+          For documentation see
+          <ulink url='http://www.torque.net/sg/sdebug26.html'>http://www.torque.net/sg/sdebug26.html</ulink>
+        </para>
+<!-- !Edrivers/scsi/scsi_debug.c -->
+      </sect2>
+      <sect2 id="todo">
+        <title>todo</title>
+        <para>Parallel (fast/wide/ultra) SCSI, USB, SATA,
+        SAS, Fibre Channel, FireWire, ATAPI devices, Infiniband,
+        I20, iSCSI, Parallel ports, netlink...
+        </para>
+      </sect2>
+    </sect1>
+  </chapter>
+</book>
diff --git a/drivers/scsi/constants.c b/drivers/scsi/constants.c
index fac4314cd2a..403a7f2d8f9 100644
--- a/drivers/scsi/constants.c
+++ b/drivers/scsi/constants.c
@@ -362,7 +362,6 @@ void scsi_print_command(struct scsi_cmnd *cmd)
 EXPORT_SYMBOL(scsi_print_command);
 
 /**
- *
  *	scsi_print_status - print scsi status description
  *	@scsi_status: scsi status value
  *
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 24271a871b8..9a10b4335e7 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -54,8 +54,7 @@ static struct class shost_class = {
 };
 
 /**
- *	scsi_host_set_state - Take the given host through the host
- *		state model.
+ *	scsi_host_set_state - Take the given host through the host state model.
  *	@shost:	scsi host to change the state of.
  *	@state:	state to change to.
  *
@@ -431,7 +430,6 @@ EXPORT_SYMBOL(scsi_unregister);
 
 /**
  * scsi_host_lookup - get a reference to a Scsi_Host by host no
- *
  * @hostnum:	host number to locate
  *
  * Return value:
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 0fb1709ce5e..412a351c6cf 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -122,6 +122,11 @@ static const char *const scsi_device_types[] = {
 	"Automation/Drive ",
 };
 
+/**
+ * scsi_device_type - Return 17 char string indicating device type.
+ * @type: type number to look up
+ */
+
 const char * scsi_device_type(unsigned type)
 {
 	if (type == 0x1e)
@@ -156,6 +161,14 @@ static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
 
 static DEFINE_MUTEX(host_cmd_pool_mutex);
 
+/**
+ * __scsi_get_command - Allocate a struct scsi_cmnd
+ * @shost: host to transmit command
+ * @gfp_mask: allocation mask
+ *
+ * Description: allocate a struct scsi_cmd from host's slab, recycling from the
+ *              host's free_list if necessary.
+ */
 struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
 {
 	struct scsi_cmnd *cmd;
@@ -179,13 +192,10 @@ struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
 }
 EXPORT_SYMBOL_GPL(__scsi_get_command);
 
-/*
- * Function:	scsi_get_command()
- *
- * Purpose:	Allocate and setup a scsi command block
- *
- * Arguments:	dev	- parent scsi device
- *		gfp_mask- allocator flags
+/**
+ * scsi_get_command - Allocate and setup a scsi command block
+ * @dev: parent scsi device
+ * @gfp_mask: allocator flags
  *
  * Returns:	The allocated scsi command structure.
  */
@@ -217,6 +227,12 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(scsi_get_command);
 
+/**
+ * __scsi_put_command - Free a struct scsi_cmnd
+ * @shost: dev->host
+ * @cmd: Command to free
+ * @dev: parent scsi device
+ */
 void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
 			struct device *dev)
 {
@@ -237,12 +253,9 @@ void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
 }
 EXPORT_SYMBOL(__scsi_put_command);
 
-/*
- * Function:	scsi_put_command()
- *
- * Purpose:	Free a scsi command block
- *
- * Arguments:	cmd	- command block to free
+/**
+ * scsi_put_command - Free a scsi command block
+ * @cmd: command block to free
  *
  * Returns:	Nothing.
  *
@@ -263,12 +276,13 @@ void scsi_put_command(struct scsi_cmnd *cmd)
 }
 EXPORT_SYMBOL(scsi_put_command);
 
-/*
- * Function:	scsi_setup_command_freelist()
- *
- * Purpose:	Setup the command freelist for a scsi host.
+/**
+ * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
+ * @shost: host to allocate the freelist for.
  *
- * Arguments:	shost	- host to allocate the freelist for.
+ * Description: The command freelist protects against system-wide out of memory
+ * deadlock by preallocating one SCSI command structure for each host, so the
+ * system can always write to a swap file on a device associated with that host.
  *
  * Returns:	Nothing.
  */
@@ -282,7 +296,7 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost)
 
 	/*
 	 * Select a command slab for this host and create it if not
-	 * yet existant.
+	 * yet existent.
 	 */
 	mutex_lock(&host_cmd_pool_mutex);
 	pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool);
@@ -318,12 +332,9 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost)
 
 }
 
-/*
- * Function:	scsi_destroy_command_freelist()
- *
- * Purpose:	Release the command freelist for a scsi host.
- *
- * Arguments:	shost	- host that's freelist is going to be destroyed
+/**
+ * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
+ * @shost: host whose freelist is going to be destroyed
  */
 void scsi_destroy_command_freelist(struct Scsi_Host *shost)
 {
@@ -441,8 +452,12 @@ void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
 }
 #endif
 
-/* 
- * Assign a serial number to the request for error recovery
+/**
+ * scsi_cmd_get_serial - Assign a serial number to a command
+ * @host: the scsi host
+ * @cmd: command to assign serial number to
+ *
+ * Description: a serial number identifies a request for error recovery
  * and debugging purposes.  Protected by the Host_Lock of host.
  */
 static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
@@ -452,14 +467,12 @@ static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd
 		cmd->serial_number = host->cmd_serial_number++;
 }
 
-/*
- * Function:    scsi_dispatch_command
- *
- * Purpose:     Dispatch a command to the low-level driver.
- *
- * Arguments:   cmd - command block we are dispatching.
+/**
+ * scsi_dispatch_command - Dispatch a command to the low-level driver.
+ * @cmd: command block we are dispatching.
  *
- * Notes:
+ * Return: nonzero return request was rejected and device's queue needs to be
+ * plugged.
  */
 int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 {
@@ -585,7 +598,7 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 
 /**
  * scsi_req_abort_cmd -- Request command recovery for the specified command
- * cmd: pointer to the SCSI command of interest
+ * @cmd: pointer to the SCSI command of interest
  *
  * This function requests that SCSI Core start recovery for the
  * command by deleting the timer and adding the command to the eh
@@ -606,9 +619,9 @@ EXPORT_SYMBOL(scsi_req_abort_cmd);
  * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
  * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
  *
- * This function is the mid-level's (SCSI Core) interrupt routine, which
- * regains ownership of the SCSI command (de facto) from a LLDD, and enqueues
- * the command to the done queue for further processing.
+ * Description: This function is the mid-level's (SCSI Core) interrupt routine,
+ * which regains ownership of the SCSI command (de facto) from a LLDD, and
+ * enqueues the command to the done queue for further processing.
  *
  * This is the producer of the done queue who enqueues at the tail.
  *
@@ -617,7 +630,7 @@ EXPORT_SYMBOL(scsi_req_abort_cmd);
 static void scsi_done(struct scsi_cmnd *cmd)
 {
 	/*
-	 * We don't have to worry about this one timing out any more.
+	 * We don't have to worry about this one timing out anymore.
 	 * If we are unable to remove the timer, then the command
 	 * has already timed out.  In which case, we have no choice but to
 	 * let the timeout function run, as we have no idea where in fact
@@ -660,10 +673,11 @@ static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
 	return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
 }
 
-/*
- * Function:    scsi_finish_command
+/**
+ * scsi_finish_command - cleanup and pass command back to upper layer
+ * @cmd: the command
  *
- * Purpose:     Pass command off to upper layer for finishing of I/O
+ * Description: Pass command off to upper layer for finishing of I/O
  *              request, waking processes that are waiting on results,
  *              etc.
  */
@@ -708,18 +722,14 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
 }
 EXPORT_SYMBOL(scsi_finish_command);
 
-/*
- * Function:	scsi_adjust_queue_depth()
- *
- * Purpose:	Allow low level drivers to tell us to change the queue depth
- * 		on a specific SCSI device
- *
- * Arguments:	sdev	- SCSI Device in question
- * 		tagged	- Do we use tagged queueing (non-0) or do we treat
- * 			  this device as an untagged device (0)
- * 		tags	- Number of tags allowed if tagged queueing enabled,
- * 			  or number of commands the low level driver can
- * 			  queue up in non-tagged mode (as per cmd_per_lun).
+/**
+ * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
+ * @sdev: SCSI Device in question
+ * @tagged: Do we use tagged queueing (non-0) or do we treat
+ *          this device as an untagged device (0)
+ * @tags: Number of tags allowed if tagged queueing enabled,
+ *        or number of commands the low level driver can
+ *        queue up in non-tagged mode (as per cmd_per_lun).
  *
  * Returns:	Nothing
  *
@@ -742,8 +752,8 @@ void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
 
 	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
 
-	/* Check to see if the queue is managed by the block layer
-	 * if it is, and we fail to adjust the depth, exit */
+	/* Check to see if the queue is managed by the block layer.
+	 * If it is, and we fail to adjust the depth, exit. */
 	if (blk_queue_tagged(sdev->request_queue) &&
 	    blk_queue_resize_tags(sdev->request_queue, tags) != 0)
 		goto out;
@@ -772,20 +782,17 @@ void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
 }
 EXPORT_SYMBOL(scsi_adjust_queue_depth);
 
-/*
- * Function:	scsi_track_queue_full()
+/**
+ * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
+ * @sdev: SCSI Device in question
+ * @depth: Current number of outstanding SCSI commands on this device,
+ *         not counting the one returned as QUEUE_FULL.
  *
- * Purpose:	This function will track successive QUEUE_FULL events on a
+ * Description:	This function will track successive QUEUE_FULL events on a
  * 		specific SCSI device to determine if and when there is a
  * 		need to adjust the queue depth on the device.
  *
- * Arguments:	sdev	- SCSI Device in question
- * 		depth	- Current number of outstanding SCSI commands on
- * 			  this device, not counting the one returned as
- * 			  QUEUE_FULL.
- *
- * Returns:	0 - No change needed
- * 		>0 - Adjust queue depth to this new depth
+ * Returns:	0 - No change needed, >0 - Adjust queue depth to this new depth,
  * 		-1 - Drop back to untagged operation using host->cmd_per_lun
  * 			as the untagged command depth
  *
@@ -824,10 +831,10 @@ int scsi_track_queue_full(struct scsi_device *sdev, int depth)
 EXPORT_SYMBOL(scsi_track_queue_full);
 
 /**
- * scsi_device_get  -  get an addition reference to a scsi_device
+ * scsi_device_get  -  get an additional reference to a scsi_device
  * @sdev:	device to get a reference to
  *
- * Gets a reference to the scsi_device and increments the use count
+ * Description: Gets a reference to the scsi_device and increments the use count
  * of the underlying LLDD module.  You must hold host_lock of the
  * parent Scsi_Host or already have a reference when calling this.
  */
@@ -849,8 +856,8 @@ EXPORT_SYMBOL(scsi_device_get);
  * scsi_device_put  -  release a reference to a scsi_device
  * @sdev:	device to release a reference on.
  *
- * Release a reference to the scsi_device and decrements the use count
- * of the underlying LLDD module.  The device is freed once the last
+ * Description: Release a reference to the scsi_device and decrements the use
+ * count of the underlying LLDD module.  The device is freed once the last
  * user vanishes.
  */
 void scsi_device_put(struct scsi_device *sdev)
@@ -867,7 +874,7 @@ void scsi_device_put(struct scsi_device *sdev)
 }
 EXPORT_SYMBOL(scsi_device_put);
 
-/* helper for shost_for_each_device, thus not documented */
+/* helper for shost_for_each_device, see that for documentation */
 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
 					   struct scsi_device *prev)
 {
@@ -895,6 +902,8 @@ EXPORT_SYMBOL(__scsi_iterate_devices);
 /**
  * starget_for_each_device  -  helper to walk all devices of a target
  * @starget:	target whose devices we want to iterate over.
+ * @data:	Opaque passed to each function call.
+ * @fn:		Function to call on each device
  *
  * This traverses over each device of @starget.  The devices have
  * a reference that must be released by scsi_host_put when breaking
@@ -946,13 +955,13 @@ EXPORT_SYMBOL(__starget_for_each_device);
  * @starget:	SCSI target pointer
  * @lun:	SCSI Logical Unit Number
  *
- * Looks up the scsi_device with the specified @lun for a give
- * @starget. The returned scsi_device does not have an additional
+ * Description: Looks up the scsi_device with the specified @lun for a given
+ * @starget.  The returned scsi_device does not have an additional
  * reference.  You must hold the host's host_lock over this call and
  * any access to the returned scsi_device.
  *
  * Note:  The only reason why drivers would want to use this is because
- * they're need to access the device list in irq context.  Otherwise you
+ * they need to access the device list in irq context.  Otherwise you
  * really want to use scsi_device_lookup_by_target instead.
  **/
 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
@@ -974,9 +983,9 @@ EXPORT_SYMBOL(__scsi_device_lookup_by_target);
  * @starget:	SCSI target pointer
  * @lun:	SCSI Logical Unit Number
  *
- * Looks up the scsi_device with the specified @channel, @id, @lun for a
- * give host.  The returned scsi_device has an additional reference that
- * needs to be release with scsi_host_put once you're done with it.
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a given host.  The returned scsi_device has an additional reference that
+ * needs to be released with scsi_device_put once you're done with it.
  **/
 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
 						 uint lun)
@@ -996,19 +1005,19 @@ struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
 EXPORT_SYMBOL(scsi_device_lookup_by_target);
 
 /**
- * scsi_device_lookup - find a device given the host (UNLOCKED)
+ * __scsi_device_lookup - find a device given the host (UNLOCKED)
  * @shost:	SCSI host pointer
  * @channel:	SCSI channel (zero if only one channel)
- * @pun:	SCSI target number (physical unit number)
+ * @id:		SCSI target number (physical unit number)
  * @lun:	SCSI Logical Unit Number
  *
- * Looks up the scsi_device with the specified @channel, @id, @lun for a
- * give host. The returned scsi_device does not have an additional reference.
- * You must hold the host's host_lock over this call and any access to the
- * returned scsi_device.
+ * Description: Looks up the scsi_device with the specified @channel, @id, @lun
+ * for a given host. The returned scsi_device does not have an additional
+ * reference.  You must hold the host's host_lock over this call and any access
+ * to the returned scsi_device.
  *
  * Note:  The only reason why drivers would want to use this is because
- * they're need to access the device list in irq context.  Otherwise you
+ * they need to access the device list in irq context.  Otherwise you
  * really want to use scsi_device_lookup instead.
  **/
 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
@@ -1