Alex, Thank you so much for clarifying this. It surely explains why I couldn’t find any documentation on how to do that!!! Seems like, taking this in account, we are going to go the i2c route… Thanks again /Patrick > On 30 Jul 2021, at 09:30, Alexandru Ardelean <ardeleanalex@xxxxxxxxx> wrote: > > On Fri, Jul 30, 2021 at 11:03 AM <patrick@xxxxxxxxxxxxxx> wrote: >> >> 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. > > Wait, I'm confusing/mixing triggers and events [in my head]. > Apologies. I'm still processing the coffee I ingested 1-2h ago. > > libiio supports triggers. But not events. > > However, the driver for LSM6DSLTR (i.e. the one here > drivers/iio/imu/st_lsm6dsx) doesn't register any IIO triggers. > So, there's nothing for libiio [or any userspace tool] to hook into > for triggers. > > There's an IRQ handler and IRQ thread-handler, but nothing to link > these to IIO framework triggers. > This needs to be implemented in the driver. > An example of how IIO kernel triggers should be implemented in the > driver is in drivers/iio/accel/adxl372.c and drivers/iio/imu/adis*** > drivers. > >>> >>> 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 >> >> >>
