[Tinkerphones] ***UNCHECKED*** RE: Some questions about GTA04 and Neo900

roy jackson roy.r.jackson at outlook.com
Tue Jul 26 17:50:09 CEST 2016


Hi,

I've switched from web interface to a proper e-mail client. :)

On Tue, 2016-07-26 at 09:04 +0200, H. Nikolaus Schaller wrote:
> Hi,
> 
> > 
> > Am 26.07.2016 um 05:23 schrieb roy jackson <roy.r.jackson at outlook.c
> > om>:
> > 
> > 
> > Hi,
> > 
> > > 
> > > As long as you find source code that works on a BeagleBoard (XM)
> > > it appears to be a not that difficult task to adjust and add
> > > drivers for
> > > peripherals not supported by the BeagleBoard (mainly display,
> > > touch,
> > > i2c based sensors, audio). But if you have to port a kernel to
> > > the
> > > processor first, it is a real challenge...
> > Not really ... 
> > 
> > * https://wiki.freebsd.org/BeagleBoard
> > 
> > btw
> > 
> > * http://blog.khubla.com/freebsd/building-a-beaglebone-freebsd-kern
> > el
> Ah, nice!
> 

Here, a lot of more information: 

 * https://wiki.freebsd.org/FreeBSD/arm

> > 
> > 
> > The "hard thing" is the display, but ncurses(3) suits well for my 
> > "purposes" in context of present developement activities. 
> > 
> > Sooner or later, I'll start experimenting with the frame buffer
> > in cotext of virtual terminal device vt(4) ... :)
> > 
> > * https://www.freebsd.org/cgi/man.cgi?query=vt&sektion=4&manpath=Fr
> > eeBSD+10.3-RELEASE+and+Ports
> For the display there is only some hardware dependent initialization
> of the display controller
> so that it sends a memory region (frame buffer) to the panel.
> 
> We do that within U-Boot as well, so it might be as simple as copying
> that code:
> 
> http://git.goldelico.com/?p=gta04-uboot.git;a=blob;f=board/goldelico/
> gta04/dssfb.c;h=4eff169aa9b985f2606ac5b251c624691ac78b5f;hb=ab10e1164
> 63b384b21b2b96ff1173f2a0014a817
> 

That's great work! What a fortune, because I've 
learned about the existence of OpenPhoenux.org 
only by a fluke.

> > 
> > 
> > > 
> > > The list of sensors of the GTA04 is included in the manual:
> > > http://projects.goldelico.com/p/gta04-main/page/Manual/
> > > 
> > > There will be an update for the GTA04A5 board (some
> > > sensors and i2c addresses have changed).
> > > 
> > Fantastic! This is it what I've searched for. 
> > 
> > Thank you for the (hard) work compiling this
> > outstanding manual!
> > 
> > > 
> > > > 
> > > > 
> > > > Are all integrated HW sensors deployed with same kind 
> > > > of controlling MC?
> > > > 
> > > > 
> > > > Exists a listing about ioctl(2) primitives which are accepted
> > > > by WH sensors controlling MC?
> > > On Linux sensors are more and more controlled by the iio
> > > framework which allows to either read them (inefficiently) as
> > > text files through /sys (usually /sys/class/iio). Or by opening
> > > a file that presents a stream of iio data records.
> > Ahhh... I've understood. The Interfaces against HW Sensors 
> > areimplemented (top-half) as character devices (bottom-half)  
> > throught "ioo" Kernel Progarmmers Interface (KPI)?
> Yes.
> 
> > 
> > 
> > I've planned to implement an interface against HW sensors by 
> > utilizing OpenBSD HW Sensors Framework (is ported to FreeBSD) 
> > for this purpose.
> > 
> > * https://www.openbsd.org/papers/asiabsdcon2009-sensors-paper.pdf
> From a first look though it (I have no OpenBSD experience) it looks
> roughly equivalent to the Linux iio approach. Details are of course
> very different.
> 

Here, the interface specification

 * http://bxr.su/OpenBSD/sys/sys/sensors.h
 
and 

 * http://bxr.su/OpenBSD/sys/dev/i2c/w83793g.c

as a working example (kernelspace). By HW sensors 
collected data are passed through sysctl(3) 

 * http://man.openbsd.org/OpenBSD-current/man3/sysctl.3

into userspace, e. g. sensorsd(8) provides a generic 
backend for local distribution of collected data and 
monitoring.

 * http://man.openbsd.org/OpenBSD-current/man8/sensorsd.8
 * http://man.openbsd.org/sensorsd.conf.5
 * http://bxr.su/OpenBSD/usr.sbin/sensorsd/sensorsd.c 

Well, the sysctl(3) approach looks for me a little bit more
effective  than using a cycle based on open(2), read(2), ioctl(2) [and
close(2)] accessor methods for passing data into user space in context
of an character device.

> > 
> > 
> > > 
> > > Hope that this helps a little, even if it is less than 50%
> > > answered :)
> > Thank you! This helps me a lot in multiple ways! :)
> > 
> > How I can order the GTA04A5 board (for developement purposes)?
> Here: http://shop.goldelico.com/wiki.php?page=GTA04

Fantastic!

BR,
Roy





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