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<div class="moz-cite-prefix">On 4/17/2014 5:42 AM, Andre Marques
wrote:<br>
</div>
<blockquote cite="mid:534FA208.8000109@gmail.com" type="cite">
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
<div class="moz-cite-prefix">On 04/17/14 03:22, Alan Cudmore
wrote:<br>
</div>
<blockquote
cite="mid:CAJrjN72cofLqdbUeXAdzNCgiNy=QT1HAVDiihLi7tODF1-DCAg@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Apr 16, 2014 at 4:49 PM,
Joel Sherrill <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:joel.sherrill@oarcorp.com"
target="_blank">joel.sherrill@oarcorp.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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<div>
<div class="h5"> <br>
<div>On 4/16/2014 2:06 PM, Alan Cudmore wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Thu, Apr 10,
2014 at 7:11 PM, Andre Marques <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:andre.lousa.marques@gmail.com" target="_blank">andre.lousa.marques@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div>On 04/04/14 20:19, Joel Sherrill
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
On 4/4/2014 1:15 PM, Gedare Bloom
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
The license looked fine to me.<br>
</blockquote>
+1<br>
<br>
As always, we just need to be
careful on a file per file basis
just in case<br>
something else in rpi-boot has a
different license.<br>
</blockquote>
<br>
</div>
All files in rpi-boot use a similar
licence, so I will be using some code
from rpi-boot as a base for this.</blockquote>
<div><br>
</div>
<div>Great.</div>
<div> </div>
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<div><br>
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On Thu, Apr 3, 2014 at 10:06 PM,
Alan Cudmore <<a
moz-do-not-send="true"
href="mailto:alan.cudmore@gmail.com"
target="_blank">alan.cudmore@gmail.com</a>>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
From my limited research, it
looks like the emmc controller
in the Raspberry<br>
Pi BCM2835 may be the way to go.<br>
It looks like it is a high level
controller for the SD/MMC card
slot on the<br>
Pi.<br>
<br>
Since this is a custom
controller, I don't think there
would be an existing<br>
driver in RTEMS.<br>
<br>
It seems that this emmc
controller in the Pi may handle
different types of<br>
cards, and at a higher level
than just using the SPI bus to
access the card.<br>
( This is based on some searches
of conversations on the
raspberry pi forums<br>
, not my experience )<br>
<br>
You would have to write a driver
for this emmc controller and
provide the<br>
interface to libblock for the
file system interface on RTEMS.
The code you<br>
have linked above for rpi-boot
looks like it has a permissive
license, so it<br>
*may* be possible to use this
code in the RTEMS driver. There
is some other<br>
potentially useful code in there
too.<br>
</blockquote>
</blockquote>
</blockquote>
<br>
</div>
The mailbox access, mmio read and write
and the timer code will also be usefull,
and not only for emmc. This timer code
differs from the misc/timer.h currently
in the raspberrypi BSP, as it waits a
certain amount of time (until some
register gets updated). The misc/timer.h
is a benchmark timer, so one of them
would have to be renamed or reorganized.<br>
<br>
</blockquote>
<div><br>
</div>
<div>Can an RTEMS timer be used for the
mailbox communication? </div>
<div>Also, I don't think the benchmark
timer code in the RTEMS Raspberry Pi BSP
is functional.</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
</div>
</div>
Do you mean rtems_timer_XXX or the timer in the BSP?<br>
</div>
</blockquote>
<div><br>
</div>
<div>I mean the rtems_timer_ api. Maybe we can use this,
or other RTEMS features to implement the mailbox
interface rather than just going directly to the timer
hardware like we see in the "bare metal" examples. </div>
<div> </div>
</div>
</div>
</div>
</blockquote>
<br>
Maybe the "timer" concept here is a little misleading. I was
talking about a wait with timeout, until some register gets
updated. The rtems_timer api schedules a routine to be executed
after some period of time, but the register may (and should) be
updated before the timeout. <br>
<br>
I am not sure if this would be recommended, but using the
rtems_timer api a timer could be set for a period of time (the
timeout), and while the timer is going the driver would check if
the register has been updated. If so the timer would be cancelled.
Is this good practice with the rtems_timer api?<br>
</blockquote>
<br>
I agree that the rtems_timer might not be the best mechanism for the
waiting on the mailbox.<br>
If the CPU<->GPU interface supports interrupts, then a
non-blocking driver could be written.<br>
Otherwise, what is the best approach? <br>
- a sleep call<br>
- polling a status register<br>
<br>
While I am on the subject of polling, I just remembered that the
UART driver in the BSP does not support interrupts. We should look
at this sometime too. <br>
<br>
<blockquote cite="mid:534FA208.8000109@gmail.com" type="cite"> <br>
<blockquote
cite="mid:CAJrjN72cofLqdbUeXAdzNCgiNy=QT1HAVDiihLi7tODF1-DCAg@mail.gmail.com"
type="cite">
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<div bgcolor="#FFFFFF" text="#000000"> <br>
The timer driver in the BSP is strictly for
benchmarking -- nothing else. It is used<br>
by the tmtests and psxtmtests. It should not be used
for any other purpose.<br>
<br>
How does the mailbox work? Describe it and we can
figure out how to best address<br>
it. <br>
</div>
</blockquote>
<div><br>
</div>
<div>The mailbox is the interface between the Video Core
GPU and the ARM processor on the Pi. Here are some docs:</div>
<div><a moz-do-not-send="true"
href="https://github.com/raspberrypi/firmware/wiki/Mailboxes">https://github.com/raspberrypi/firmware/wiki/Mailboxes</a><br>
</div>
<div><a moz-do-not-send="true"
href="https://github.com/raspberrypi/firmware/wiki/Accessing-mailboxes">https://github.com/raspberrypi/firmware/wiki/Accessing-mailboxes</a><br>
</div>
<div><a moz-do-not-send="true"
href="https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface">https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface</a><br>
</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
The mailbox interface is a register that has several channels
("mail accounts") for different resources on the board, so a
driver sends a buffer with a request (an "email") to one of them
and gets answers. This is an abstraction layer mainly usefull to
communicate with the GPU since its documentation isn't available
(that is how I see it), but can be used to get other types of
information, not related with the GPU. <br>
<br>
Any work with the GPU, however, will probably need to use this
interface.<br>
<br>
In practice it is just a matter of dealing with reading and
writting to the mailbox registers, following a small protocol.
This could be put into the misc directory in the Raspberry Pi BSP.<br>
<br>
One thing I haven't found on the Raspberry Pi BSP is a memory
barrier. The memory mapped i/o to the registers shoud have a
memory barrier around the read and writes to a peripheral when
more than one peripheral is being used, according to the bcm2835
datasheet (page 7).<br>
<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf">http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf</a><br>
<br>
</blockquote>
Good point. Is this memory barrier an assembly instruction? Should
we create a couple of macros that generate the inline assembly?<br>
<br>
<br>
<br>
<br>
<blockquote cite="mid:534FA208.8000109@gmail.com" type="cite">
<blockquote
cite="mid:CAJrjN72cofLqdbUeXAdzNCgiNy=QT1HAVDiihLi7tODF1-DCAg@mail.gmail.com"
type="cite">
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<div class="gmail_quote">
<div>The details of the GPU have been closed, and the
linux port has relied on a binary blob for the GPU
firmware, but Broadcom recently took a huge step in
opening it up:</div>
<div><a moz-do-not-send="true"
href="http://www.raspberrypi.org/a-birthday-present-from-broadcom/">http://www.raspberrypi.org/a-birthday-present-from-broadcom/</a><br>
</div>
<div><br>
</div>
<div>Hopefully this will help improve the understanding of
this interface.</div>
<div><br>
</div>
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<blockquote type="cite">
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<div class="gmail_extra">
<div class="gmail_quote">
<div>I have been contacted by someone who is
currently working on a console driver for
the BSP, and has been able to display
fonts. We may want to include him, because
I think the graphics code uses mailbox
communication to the GPU. </div>
<div><br>
</div>
<div>It is very interesting that the GPU is
running a commercial RTOS, and we will be
communicating to it with RTEMS.</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
</div>
:)
<div class=""><br>
<blockquote type="cite">
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<div class="gmail_quote">
<div> </div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
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My plan was to have at the root of the
raspberrypi BSP a folder "emmc" for the
emmc driver code, and the mailbox, mmio
and timer on the misc folder, with the
headers on the include folder. What do you
think?<br>
<br>
I have been trying the rpi-boot emmc code
for the past week, and I modified the
hello test to use the emmc driver (an
overly simplified version of the rpi-boot,
just to read the slot info register for
now), and my compilation process has been:<br>
<br>
1. Add/change files in Raspberrypi BSP<br>
2. Update Makefile.am<br>
3. Run bootstrap -p and bootstrap from the
RaspberryPi BSP folder<br>
4. (Re)configure RTEMS<br>
5. make and make install RTEMS from the
root folder<br>
<br>
</blockquote>
<div>That is pretty much what I do. Although
it might be possible to test drivers and
code in the RKI image, then integrate it
into the RTEMS tree when it is ready.</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
</div>
--enable-maintainer-mode is supposed to track
regenerating the Makefile.in<br>
and configure files when you modify Makefile.am or <a
moz-do-not-send="true" href="http://configure.ac"
target="_blank">configure.ac</a>.<br>
<br>
The current build system has a serious deficiency in
that it does **not** <br>
track the dependency of the test executables on any .a
or .h file from RTEMS.<br>
So the best solution for quick builds is usually to
remove the executable you<br>
are testing and then run make.<br>
<br>
Step 3 above is the minimum for a bootstrap. bootstrap
-p is only needed<br>
when you add/delete/move .h files.
<div class=""><br>
<blockquote type="cite">
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<div class="gmail_quote">
<div> </div>
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style="margin:0px 0px 0px
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I have been using the
--enable-maintainer-mode, but I am not
sure about exacly what it simplifies,
because I always needed to do those steps
for it to compile and link correctly.<br>
</blockquote>
<div><br>
</div>
<div>I don't know what this does either..</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
</div>
Just tracks dependencies on generated
Makefile/configure related files back<br>
to their source.
<div>
<div class="h5"><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div><br>
</div>
<div>Alan</div>
<div> </div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
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<br>
--André Marques
<div>
<div><br>
<br>
<blockquote class="gmail_quote"
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<blockquote class="gmail_quote"
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<blockquote class="gmail_quote"
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<br>
I'll have to try the serial
bootloader, I am also close to
ordering an<br>
inexpensive JTAG adapter to
try loading and debugging
through JTAG. uboot is<br>
another possibility, using a
TFTP server.<br>
<br>
Alan<br>
<br>
<br>
<br>
<br>
On Wed, Apr 2, 2014 at 12:02
PM, Andre Marques<br>
<<a moz-do-not-send="true"
href="mailto:andre.lousa.marques@gmail.com" target="_blank">andre.lousa.marques@gmail.com</a>>
wrote:<br>
<blockquote
class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
Hello,<br>
<br>
I'm intending to work in the
SD card support for the
Raspberry Pi BSP,<br>
using the SD mode instead of
the SPI mode.<br>
<br>
The references I have
gathered so far for this are
as follows:<br>
<br>
The Raspberry Pi SOC guide:
Broadcom BCM2835 Peripherals
Guide (Chapter 5<br>
- EMMC)<br>
<br>
The simplified SD standard -<br>
<a moz-do-not-send="true"
href="https://www.sdcard.org/downloads/pls/simplified_specs/"
target="_blank">https://www.sdcard.org/downloads/pls/simplified_specs/</a><br>
<br>
And the following github
code -<br>
<a moz-do-not-send="true"
href="https://github.com/jncronin/rpi-boot/blob/master/emmc.c"
target="_blank">https://github.com/jncronin/rpi-boot/blob/master/emmc.c</a><br>
<br>
There is also the
libchip/i2c/spi-sd-card
libi2c driver, which can
also be<br>
a reference (even though it
uses SPI).<br>
<br>
Now, the questions:<br>
<br>
Should I use the Generic
Disk Device driver, as the<br>
libchip/i2c/spi-sd-card ?<br>
<br>
Is there any driver using
the SD mode for sd card
access, or using an emmc<br>
interface currently in the
RTEMS code base? I haven't
found any.<br>
<br>
On a side note, I managed to
send RTEMS applications to
the RPi though the<br>
UART interface using the
xmodem protocol.<br>
<br>
For that I used the
following bootloader<br>
<br>
<a moz-do-not-send="true"
href="https://github.com/dwelch67/raspberrypi/tree/master/bootloader05"
target="_blank">https://github.com/dwelch67/raspberrypi/tree/master/bootloader05</a><br>
<br>
It takes me 2 minutes to
send 1 MB of data to the
RPi, but this could be<br>
improved if it used 1024
byte block transfer instead
of the default of 128.<br>
The bootloader loads the
transfered program to memory
and runs it. Then the<br>
RPi must be rebooted so a
new program can be sent.<br>
<br>
It may not be the best way,
but only requires an
usb-to-uart cable, and<br>
avoids the current SD card
"dance" to run programs on
the Pi.<br>
<br>
Thank you for your time.<br>
<br>
--André Marques<br>
<br>
<br>
</blockquote>
_______________________________________________<br>
rtems-devel mailing list<br>
<a moz-do-not-send="true"
href="mailto:rtems-devel@rtems.org"
target="_blank">rtems-devel@rtems.org</a><br>
<a moz-do-not-send="true"
href="http://www.rtems.org/mailman/listinfo/rtems-devel"
target="_blank">http://www.rtems.org/mailman/listinfo/rtems-devel</a><br>
<br>
</blockquote>
_______________________________________________<br>
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<a moz-do-not-send="true"
href="mailto:rtems-devel@rtems.org"
target="_blank">rtems-devel@rtems.org</a><br>
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href="http://www.rtems.org/mailman/listinfo/rtems-devel"
target="_blank">http://www.rtems.org/mailman/listinfo/rtems-devel</a><br>
</blockquote>
</blockquote>
<br>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
<br>
</div>
</div>
<div class="">
<pre cols="72">--
Joel Sherrill, Ph.D. Director of Research & Development
<a moz-do-not-send="true" href="mailto:joel.sherrill@OARcorp.com" target="_blank">joel.sherrill@OARcorp.com</a> On-Line Applications Research
Ask me about RTEMS: a free RTOS Huntsville AL 35805
Support Available <a moz-do-not-send="true" href="tel:%28256%29%20722-9985" value="+12567229985" target="_blank">(256) 722-9985</a></pre>
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