The original scrub rate API definition states that if scrub rate
accessors are not implemented, a negative value (-1) should be written
to the sysfs file (/sys/devices/system/edac/mc/mc<N>/sdram_scrub_rate,
where N is the memory controller number on the system). This is
counter-intuitive and awkward at the very least because, when setting
the scrub rate, userspace has to write to sysfs and then read it back to
check error status of the operation.

As Tony notes, best it would be to not have the sdram_scrub_rate in
sysfs if scrub rate support is not implemented. It is too late about
that and a bunch of drivers on a bunch of arches would need to be
changed and tested which is not a trivial task ATM.

Instead, settle for the next best thing of returning -ENODEV when
implementation is missing and -EINVAL when there was an error
encountered while setting the scrub rate.
Reported-by: NHan Pingtian <phan@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20110916105856.GA13253@hpt.nay.redhat.comSigned-off-by: NBorislav Petkov <borislav.petkov@amd.com>

Fix some minor typos:
 * informations => information
 * there own => their own
 * these => this
Signed-off-by: NSylvestre Ledru <sylvestre.ledru@scilab.org>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

Fix trivial typos in edac.txt
Signed-off-by: NRaoul Bhatia <r.bhatia@ipax.at>
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>

Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: NMauro Carvalho Chehab <mcheahb@redhat.com>

As Nehalem has a different binding to EDAC API, and its own different
error injection code, documents it.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Trivial patch fixes some typos in the Documentation/edac.txt file.
Acked-by: NDoug Thompson <dougthompson@xmission.com>
Signed-off-by: NDavidlohr Bueso <dave@gnu.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Fix various typos in documentation txts.
Signed-off-by: NMatt LaPlante <kernel1@cyberdogtech.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

/sys/devices/system/edac/mc has a few files which are duplicated in
/sys/module/edac_core/parameters.  Now that all the functionality is
duplicated between these two locations, we remove the former kobject
attributes and update the documentation.
Signed-off-by: NArthur Jones <ajones@riverbed.com>
Signed-off-by: NDoug Thompson <dougthompson@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There's no reason for edac.txt for being at this unusual place.
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Acked-by: NAlan Cox <alan@redhat.com>
Cc: Doug Thompson <norsk5@yahoo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Updated the EDAC kernel documentation
Signed-off-by: NDoug Thompson <dougthompson@xmission.com>
Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is an attempt of providing an interface for memory scrubbing control in
EDAC.

This patch modifies the EDAC Core to provide the Interface for memory
controller modules to implment.

The following things are still outstanding:

 - K8 is the first implemenation,

   The patch provide a method of configuring the K8 hardware memory scrubber
   via the 'mcX' sysfs directory.  There should be some fallback to a generic
   scrubber implemented in software if the hardware does not support
   scrubbing.

   Or .. the scrubbing sysfs entry should not be visible at all.

 - Only works with SDRAM, not cache,

   The K8 can scrub cache and l2cache also - but I think this is not so
   useful as the cache is busy all the time (one hopes).

   One would also expect that cache scrubbing requires hardware support.

 - Error Handling,

   I would like that errors are returned to the user in "terms of file
   system".

 - Presentation,

   I chose Bandwidth in Bytes/Second as a representation of the scrubbing
   rate for the following reasons:

   I like that the sysfs entries are sort-of textual, related to something
   that makes sense instead of magical values that must be looked up.

   "My People" wants "% main memory scrubbed per hour" others prefer "%
   memory bandwidth used" as representation, "bandwith used" makes it easy to
   calculate both versions in one-liner scripts.

   If one later wants to scrub cache, the scaling becomes wierd for K8
   changing from "blocks of 64 byte memory" to "blocks of 64 cache lines" to
   "blocks of 64 bit".  Using "bandwidth used" makes sense in all three cases,
   (I.M.O.  anyway ;-).

 - Discovery,

   There is no way to discover the possible settings and what they do
   without reading the code and the documentation.

   *I* do not know how to make that work in a practical way.

 - Bugs(??),

   other tools can set invalid values in the memory scrub control register,
   those will read back as '-1', requiring the user to reset the scrub rate.
   This is how *I* think it should be.

 - Afflicting other areas of code,

   I made changes to edac_mc.c and edac_mc.h which will show up globally -
   this is not nice, it would be better that the memory scrubbing fuctionality
   and interface could be entirely contained within the memory controller it
   applies to.

Frithiof Jensen

edac_mc.c and its .h file is a CORE helper module for EDAC
driver modules. This provides the abstraction for device specific
drivers. It is fine to modify this CORE to provide help for
new features of the the drivers

doug thompson
Signed-off-by: NFrithiof Jensen <frithiof.jensen@ericson.com>
Signed-off-by: Ndoug thompson <norsk5@xmission.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When EDAC was first introduced into the kernel it had a sysfs interface,
but due to some problems it was disabled in 2.6.16 and remained disabled in
2.6.17.

With feedback, several of the control and attribute files of that interface
had some good constructive feedback.  PCI Blacklist/Whitelist was a major
set which has design issues and it has been removed in this patch.  Instead
of storing PCI broken parity status in EDAC, it has been moved to the
pci_dev structure itself by a previous PCI patch.  A future patch will
enable that feature in EDAC by utilizing the pci_dev info.

The sysfs is now enabled in this patch, with a minimal set of control and
attribute files for examining EDAC state and for enabling/disabling the
memory and PCI operations.

The Documentation for EDAC has also been updated to reflect the new state
of EDAC operation.
Signed-off-by: NDoug Thompson <norsk5@xmisson.com>
Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix spelling errors in EDAC documentation.
Signed-off-by: NDavid S. Peterson <dsp@llnl.gov>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This is a subset of the bluesmoke project core code, stripped of the NMI work
which isn't ready to merge and some of the "interesting" proc functionality
that needs reworking or just has no place in kernel.  It requires no core
kernel changes except the added scrub functions already posted.

The goal is to merge further functionality only after the core code is
accepted and proven in the base kernel, and only at the point the upstream
extras are really ready to merge.

From: doug thompson <norsk5@xmission.com>

  This converts EDAC to sysfs and is the final chunk neccessary before EDAC
  has a stable user space API and can be considered for submission into the
  base kernel.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Ndoug thompson <norsk5@xmission.com>
Signed-off-by: NPavel Machek <pavel@suse.cz>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>