Alex,
Thank you so very much for your help, I browsed most of that
litterature already and the kernel side of it is very much covered,
understood and assimilated.
However my question is basically: How can I be alerted, for example
through a callback function, when an interruption occurs in the kernel
space and my daemon lives in userspace.
IRQ Occuring -------> Upper half of the interrupt(put the timestamp in
the buffer) ---------> Lower half of the interrupt handler (read data
and adds the timestamp in the buffer) -----------> ???? userspace
daemon (async callback of some description) that will write a log on
the HD.
I have everything up to the daemon part written and working, I seem to
understand that through libiio you can assign a trigger to a
particular channel or attribute but that is where I get stuck.
Litterature on the libiio (most notably its wiki) has a chapter on
triggers that is 4 lines long ... not very helpful to say the least.
iioinfo lists the devices present in the LSM6DSLTR (18 devices
including two triggers) and I have been unable to assign the triggers
to any device that they are not assigned to already (No such file or
directory) which I gather refer to the absence of the trigger
directory in the sysfs for that particular device.
I also gather that the sysfs directory is, of course, slave to the
kernel device tree and that the creation of that part of the device
tree is made as the driver is loaded.
So there must be a way to alter that part of the sysfs filesystem by
asking the kernel driver to provision a device in the context to
implement the trigger directory so we can assign a trigger to it
second part will be to slave that trigger to an actual IRQ (42 in my
case - as listed in /proc/interrupts) and be alerted in the userspace
daemon when a thresold has been reached in terms of either
acceleration or vibration ...
Well, this is the nuts and bolts of what I am trying to achieve. the
last part will be to write a few registers on the chip to configure
how and when IRQ will occur for any given integrated devices.
Sorry to be such a pain but I thnk my problem lies in the passage of
information from kernel space (very well documented) to the userspace
(could not find reasonable documention and/or C code examples on how
to achieve this)
Thnks again
/Patrick
Quoting Alexandru Ardelean <ardeleanalex@xxxxxxxxx>:
On Thu, Jul 29, 2021 at 3:54 PM Patrick Regnouf
<patrick@xxxxxxxxxxxxxx> wrote:
Hello,
[I did not hit Reply All on my first email]
Hey,
For libiio in particular, it's on Github:
https://github.com/analogdevicesinc/libiio
I think you could raise some questions as issues there.
And there's also a wiki that can be browsed:
https://wiki.analog.com/resources/tools-software/linux-software/libiio
https://wiki.analog.com/resources/tools-software/linux-software/libiio_internals
Now, regarding IIO events support in libiio, I am not sure [at point
in time] whether support is implemented.
But an example of getting events from IIO can be found here:
https://github.com/torvalds/linux/blob/master/tools/iio/iio_event_monitor.c
The https://github.com/torvalds/linux/blob/master/tools/iio/ folder
in the kernel should offer some basic bits about accessing IIO
devices, and getting events [which can be driver IRQ events, or kernel
IIO polling]
I was going to answer on the previous question that you raised, but I forgot.
Apologies. It's been a busy week.
Alex
Please someone tell me whether this is the right mailing list to
ask questions related to actually using libiio or actually please
point me in the right direction
To summarise I am looking for C source code that would capture an
IRQ emitted by an iio accelerometer (LSM6DSLTR) all of that using
libiio
I have successfully implemented a program that can read the x, y
and z axis but that means polling constantly. Not an option… the
iio_device_set_trigger however returns “no such file or directory “
Thanks
/Patrick
