[Openec] Announcing XO EC-1.75

Tue Jan 18 11:48:53 EST 2011

These are great news congrats on the hard work!.

Rafael Ortiz

On Tue, Jan 18, 2011 at 12:34 AM, Richard A. Smith <richard at laptop.org>wrote:

> EC-1.75
>
> OLPC is happy to announce the existence of a mostly [1] public code base
> for the embedded controller (EC) used on the XO 1.75.
>
> For the impatient:
>
> git clone git://dev.laptop.org/users/rsmith/ec-1.75
>
> Before we talk about what EC-1.75 is and what you can do with it let's
> first talk about what it's not.
>
> What it's not:
>
> EC-1.75 is not OpenEC.
>
> OpenEC [2] is an alternate EC codebase for XO-1 that was almost
> completely written by Frieder Ferlemann based on the datasheet for the
> KB3700 and bits of released information describing the XO-1 hardware.
> Although the code loads and runs on a XO-1 EC most of it is untested and
> the tree is currently unmaintained.  However, it blazed a path and
> served as a guideline for creating EC-1.75.  Many thanks to Frieder for
> his contribution.
>
> [2] http://wiki.laptop.org/go/OpenEC
>
> What it is:
>
> EC-1.75 was derived from the existing (closed) OLPC EC code base with
> all code that was not copyright OLPC or Quanta removed.  The missing
> bits were then re-implemented for the EnE KB3930 in the 1.75 A1
> prototype and currently are being ported to the EnE IO3731 in the A2
> prototype.  EC-1.75 is licensed GPL + a special linking exception and
> all code is now copyright OLPC.  EC-1.75 is also targeted exclusively at
> the 1.75 A2 board and beyond. Although parts of the code base were
> created on Gen 1.5 machines and those branches exist in the tree there
> are currently no plans to continue developing those branches.
>
> I mentioned that some of the original code carried a Quanta copyright.
> The new code now carries an OLPC copyright.  The original EC code was
> jointly developed by Quanta and OLPC, and our agreement gives both
> parties joint ownership of it.  We've used that base to create the new
> EC-1.75 code under a new OLPC copyright - Quanta jointly owns the code
> and could do the same sort of thing as well.  All code in the EC-1.75
> tree will continue to hold an OLPC copyright, so new authors must adhere
> to that practice.
>
> We realize that copyright assignment to OLPC is not an optimal situation
> for accepting contributions from the community but doing it this way
> allowed us to open up the code while keeping the man-hours of
> enhancement and bug fixing work from the previous codebase.
>
> Description of the branches in the EC-1.75 repository:
>
> 3700 :
>     Early development code for XO-1.5.
>
> 3930-A1 :
>     Port of codebase to the 1.75 A1 board.
>
> 3731 :
>     Port of codebase to the 1.75 A2 board.
>
> master :
>     Mash-up of all the above branches + development head.  Since the
> hardware for A2 only became available last week, this
> branch is changing frequently.
>
> stable :
>     Not really used right now since there isn't any stable code.
>
>
> What it's good for:
>
> Unless you have an XO 1.75 A2 board, not much.  A1 boards are now
> deprecated and will be removed from service as soon as A2 boards are
> distributed.  The KB3930 on the A1 boards will no longer be supported.
> As of this writing (Ver: 4_0.0.6) all major blocks of the EC on the A2
> board are up and running.  If you don't have a 1.75 it's still possible
> to play if you spend the time to backport the code from the master
> branch on to the 3700 branch and produce something that will work on a
> 1.5.  The 1.5 can be programmed with an external SPI programmer so you
> don't have to worry about bricking the 1.5.  The result could then be
> pulled into OpenEC as a starting point for 1.5.  Email me if you are
> interested in undertaking that task.
>
>
> Development requirements:
>
> EC-1.75 A2 currently requires you to use the Keil (non-free) or SDCC
> (free) compiler.  The SDCC compiler currently generates an image that is
> too large to fit in the 32 KiB of flash space on the IO3731 EC chip, so
> we're using Keil. [3]  We hope to move back to SDCC (see below).
> To program the EC code into an A2 you need a programmer that understands
> how to do the EnE EDI protocol.  OLPC uses external programmers with
> some custom software but OFW can also program the EC as long as the
> system is not bricked.
>
>
> [1] Mostly open:
>
> EnE, the manufacturer of the EC's, has requested that we not release
> information on various parts of the EC.  One of these parts is the PS/2
> interface which is used to talk to the keyboard and mouse.  Code that
> uses these parts is contained in a sub-module called "private" and is
> only accessible by parties that have signed the OLPC NDA agreement.  The
> special exception in the license allows linking against this private
> code without that code coming under the GPL.  On A1 boards and "as
> built" A2 boards these closed PS/2 interfaces are used.  A2 boards
> however, have the ability to route the keyboard and mouse data streams
> to the security processor on the the host SoC rather than the EC.  OLPC
> has code for the security processor that will bit-bang the PS/2
> protocol.  The main processor on the SoC can then read the keyboard and
> mouse data from the security processor rather than the EC.  This data
> path has not been fully implemented all the way to the Linux command
> line but soon after the A2 bring up dust settles it will be finished and
> undergo wider testing.  If it proves to be viable then the private code
> will be deprecated and eventually dropped from the tree.  We hope that
> removal of the PS/2 and keyboard/mouse code will bring the size back
> down to a point where an SDCC image will fit in the IO3731 and a fully
> open codebase + toolchain can be realized.
>
> [3] Works as long as you can check out the private tree.  Compile fails
> if not.
>
> Datasheets:
>
> The public datasheet for the IO3731 is available here:
>
> http://wiki.laptop.org/images/5/56/IO3731_v12_OLPC_20110117.pdf
>
> This datasheet has the descriptions of the non-public interfaces removed.
>
> Discussion:
>
> Since the OpenEC mailing list already exists [4] I don't really see much
> value in creating a list thats specific to EC-1.75.  Any discussions are
> valuable to both code bases.  Therefore please see the OpenEC list if
> you want to follow the development of EC-1.75.  Questions on this
> announcement and simple questions or discussions are fine for devel at .l.o
> but please send things like patches or very detailed questions to the
> OpenEC list.
>
> [4] http://lists.laptop.org/listinfo/openec
>
> So, that's the plan -- right now we're using a non-free compiler (Keil)
> to build a mostly free (except for PS/2) EC for 1.75, but we're near to
> replacing the non-free compiler and the non-free PS/2 code at the same
> time.  As always, we welcome your help!
>
> --
> Richard A. Smith  <richard at laptop.org>
> One Laptop per Child
> _______________________________________________
> Openec mailing list
> Openec at lists.laptop.org
> http://lists.laptop.org/listinfo/openec
>
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