Hello demo on RPI

[André Marques]

On 15-03-2015 12:32, Alan Cudmore wrote:
> Nice work Qiao!
>
> Andre had submitted the patches for GPIO, SPI, and I2C including 
> recommended fixes. It was then recommended that we switch to the new 
> Linux based I2C API, and we ( or I ) got stuck there.

I have addressed almost every Pavel's suggestion 
(https://lists.rtems.org/pipermail/devel/2014-October/008911.html), and 
the current code can be found on my last commit on my github 
(https://github.com/asuol/rtems/commit/eca62b41521da2e606f38320d31c83ec82e30ab6).

The difference from the last patch is that now each interrupt handler 
runs on its own task, and each user-defined handler may have as many 
arguments as the user may want (through a void pointer). Each pin can 
also have multiple handlers at the same time, so multiple devices may 
share a GPIO pin for interrupts, in which case each handler must inform 
if their device acknowledge the interrupt. The code is not yet 
thread-safe, so locking and compiler barriers are still missing if they 
are to be used on a concurrent environment, will try to conclude as soon 
as possible.

> For the time I have available, it was not going to be a 1 or 2 day fix 
> to move Andre's I2C implementation to the new Linux based API. It was 
> taking me a while just to understand what needed to be done.
>
> A little later today, I will try to come up with a proposal to split 
> the Pi work so it can be done by 3 participants.. But we need to 
> decide if re-doing the I2C implementation should be part of the work, 
> or if we should use Andre's initial implementation as a baseline for 
> everyone.
>

As soon as GPIO is in SPI can be sent directly, and the I2C is just a 
matter of using the new API, just refactoring the code around a bit to 
the new API functions (still have not looked at the new API 
unfortunately). Will have a look at it this week.

> Also, I will submit basic patches to create a raspberrypi2 BSP 
> variant. I have built both the raspberrypi and raspberrypi2 BSPs and 
> tested ticker so far.
>

I should receive my PI2 sometime this week, so I may be able to have a 
look at it then.

--André.

> Alan
>
>
> On Sun, Mar 15, 2015 at 7:11 AM, Gedare Bloom <gedare at rtems.org 
> <mailto:gedare at rtems.org>> wrote:
>
>
>
>     On Sun, Mar 15, 2015 at 5:50 AM, QIAO YANG <yangqiao0505 at me.com
>     <mailto:yangqiao0505 at me.com>> wrote:
>
>         Hi !
>
>         I've managed to run a hello demo on RPI B/B+, including a demo
>         for loading an image by u-boot (I don't have an ethernet cable
>         on my hand, but I'm going to be able to load the image by tftp
>         for dev).
>
>         If I've got it right, to prepare my proposal I may choose part
>         of the TODO list , look into the implementation detail and
>         schedule it. The work list may be divided for 3 students to
>         complete.
>
>         I've checked out the André's branch with GPIO, I2C, SPI
>         implementations. Should we develop based on his branch or the
>         upstream? Have we said that the I2C, SPI API has changed? I
>         wonder that if anyone is working on it and if we will merge
>         Andre's work to upstream at the begining of GSOC. If not,
>         maybe I can get start by trying to do this job.
>
>     The obvious projects I see from
>     https://devel.rtems.org/wiki/Developer/Projects/Open/ImproveRaspberryPiBSP
>     are:
>     1) Get #1-3 mergeable. May not take much. Then do #4 SD-card
>     support and refactor the i2c to use the newer cpukit/dev/i2c
>     interface.
>     2) #5 Graphics Frame Buffer + #7 HDMI/Graphics console
>     3) #6 USB + #7 Networking
>     4) Raspberry Pi 2 support, but this probably isn't enough.
>
>     -Gedare
>
>

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