On Mon, 2020-05-11 at 15:58 +0200, Lars-Peter Clausen wrote: > [External] > > On 5/11/20 3:24 PM, Ardelean, Alexandru wrote: > > On Mon, 2020-05-11 at 13:03 +0000, Ardelean, Alexandru wrote: > > > [External] > > > > > > On Mon, 2020-05-11 at 12:37 +0200, Lars-Peter Clausen wrote: > > > > [External] > > > > > > > > On 5/11/20 12:33 PM, Ardelean, Alexandru wrote: > > > > > On Sun, 2020-05-10 at 11:09 +0100, Jonathan Cameron wrote: > > > > > > [External] > > > > > > > > > > > > On Sat, 9 May 2020 10:52:14 +0200 > > > > > > Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > > > > > > > > > > > > > On 5/8/20 3:53 PM, Alexandru Ardelean wrote: > > > > > > > > [...] > > > > > > > > What I don't like, is that iio:device3 has iio:buffer3:0 (to 3). > > > > > > > > This is because the 'buffer->dev.parent = &indio_dev->dev'. > > > > > > > > But I do feel this is correct. > > > > > > > > So, now I don't know whether to leave it like that or symlink to > > > > > > > > shorter > > > > > > > > versions like 'iio:buffer3:Y' -> 'iio:device3/bufferY'. > > > > > > > > The reason for naming the IIO buffer devices to 'iio:bufferX:Y' > > > > > > > > is > > > > > > > > mostly to make the names unique. It would have looked weird to > > > > > > > > do > > > > > > > > '/dev/buffer1' if I would have named the buffer devices > > > > > > > > 'bufferX'. > > > > > > > > > > > > > > > > So, now I'm thinking of whether all this is acceptable. > > > > > > > > Or what is acceptable? > > > > > > > > Should I symlink 'iio:device3/iio:buffer3:0' -> > > > > > > > > 'iio:device3/buffer0'? > > > > > > > > What else should I consider moving forward? > > > > > > > > What means forward? > > > > > > > > Where did I leave my beer? > > > > > > > Looking at how the /dev/ devices are named I think we can provide > > > > > > > a > > > > > > > name > > > > > > > that is different from the dev_name() of the device. Have a look > > > > > > > at > > > > > > > device_get_devnode() in drivers/base/core.c. We should be able to > > > > > > > provide the name for the chardev through the devnode() callback. > > > > > > > > > > > > > > While we are at this, do we want to move the new devices into an > > > > > > > iio > > > > > > > subfolder? So iio/buffer0:0 instead of iio:buffer0:0? > > > > > > Possibly on the folder. I can't for the life of me remember why I > > > > > > decided > > > > > > not to do that the first time around - I'll leave it at the > > > > > > mysterious "it may turn out to be harder than you'd think..." > > > > > > Hopefully not ;) > > > > > I was also thinking about the /dev/iio subfolder while doing this. > > > > > I can copy that from /dev/input > > > > > They seem to do it already. > > > > > I don't know how difficult it would be. But it looks like a good > > > > > precedent. > > > > All you have to do is return "iio/..." from the devnode() callback. > > > I admit I did not look closely into drivers/input/input.c before > > > mentioning > > > this > > > as as good precedent. > > > > > > But, I looks like /dev/inpput is a class. > > > While IIO devices are a bus_type devices. > > > Should we start implementing an IIO class? or? > > What I should have highlighted [before] with this, is that there is no > > devnode() > > callback for the bus_type [type]. > But there is one in device_type :) Many thanks :) That worked nicely. I now have: root@analog:~# ls /dev/iio/* /dev/iio/iio:device0 /dev/iio/iio:device1 /dev/iio/device3: buffer0 buffer1 buffer2 buffer3 /dev/iio/device4: buffer0 It looks like I can shift these around as needed. This is just an experiment. I managed to move the iio devices under /dev/iio, though probably the IIO devices will still be around as /dev/iio:deviceX for legacy reasons. Two things remain unresolved. 1. The name of the IIO buffer device. root@analog:/sys/bus/iio/devices# ls iio\:device3/ buffer in_voltage0_test_mode name events in_voltage1_test_mode of_node iio:buffer:3:0 in_voltage_sampling_frequency power iio:buffer:3:1 in_voltage_scale scan_elements iio:buffer:3:2 in_voltage_scale_available subsystem iio:buffer:3:3 in_voltage_test_mode_available uevent Right now, each buffer device is named 'iio:buffer:X:Y'. One suggesttion was 'iio:deviceX:bufferY' I'm suspecting the latter is preferred as when you sort the folders, buffers come right after the iio:deviceX folders in /sys/bus/iio/devices. I don't feel it matters much the device name of the IIO buffer if we symlink it to a shorter form. I'm guessing, we symlink these devices to short-hand 'bufferY' folders in each 'iio:deviceX'? So, you'd get something like: drwxr-xr-x 8 root root 0 May 11 14:40 . drwxr-xr-x 4 root root 0 May 11 14:35 .. lrwxrwxrwx 1 root root 0 May 11 14:35 buffer -> iio:buffer:3:0 lrwxrwxrwx 4 root root 0 May 11 14:35 buffer0 -> iio:buffer:3:0 lrwxrwxrwx 4 root root 0 May 11 14:35 buffer1 -> iio:buffer:3:1 lrwxrwxrwx 4 root root 0 May 11 14:35 buffer2 -> iio:buffer:3:2 lrwxrwxrwx 4 root root 0 May 11 14:35 buffer3 -> iio:buffer:3:3 drwxrwxrwx 2 root root 0 May 11 14:35 events drwxrwxrwx 4 root root 0 May 11 14:35 iio:buffer:3:0 drwxrwxrwx 4 root root 0 May 11 14:35 iio:buffer:3:1 drwxrwxrwx 4 root root 0 May 11 14:35 iio:buffer:3:2 drwxrwxrwx 4 root root 0 May 11 14:35 iio:buffer:3:3 -rw-rw-rw- 1 root root 4096 May 11 14:35 in_voltage0_test_mode -rw-rw-rw- 1 root root 4096 May 11 14:35 in_voltage1_test_mode -rw-rw-rw- 1 root root 4096 May 11 14:35 in_voltage_sampling_frequency -rw-rw-rw- 1 root root 4096 May 11 14:35 in_voltage_scale -rw-rw-rw- 1 root root 4096 May 11 14:35 in_voltage_scale_available -rw-rw-rw- 1 root root 4096 May 11 14:35 in_voltage_test_mode_available -rw-rw-rw- 1 root root 4096 May 11 14:35 name lrwxrwxrwx 1 root root 0 May 11 14:35 of_node -> ../../../../../firmware/devicetree/base/fpga-axi@0/axi-ad9680-hpc@44a10000 drwxrwxrwx 2 root root 0 May 11 14:35 power lrwxrwxrwx 1 root root 0 May 11 14:35 scan_elements -> iio:buffer:3:0/scan_elements lrwxrwxrwx 1 root root 0 May 11 14:35 subsystem -> ../../../../../bus/iio -rw-rw-rw- 1 root root 4096 May 11 14:35 uevent 1a. /sys/bus/iio/devices looks like this: iio:buffer:3:0 (this would become iio:device3:buffer0 ) iio:buffer:3:1 iio:buffer :3:2 iio:buffer:3:3 iio:buffer:4:0 iio:device0 iio:device1 iio:device2 iio:device3 iio: device4 One minor issue here is that the buffers get listed in the /sys/bus/iio/devices folder, because I'm adding them to the iio bus, to be able to get a chardev [from the pre-allocated chardev region of IIO]. libiio gets a little confused, as it sees these buffers are IIO buffer capable devices; iio:buffer:3:0: (buffer capable) 2 channels found: voltage0: (input, index: 0, format: le:S14/16>>0) voltage1: (input, index: 1, format: le:S14/16>>0) 5 device-specific attributes found: attr 0: data_available value: 0 attr 1: enable value: 0 attr 2: length value: 4096 attr 3: length_align_bytes value: 8 attr 4: watermark value: 2048 iio:buffer:3:1: (buffer capable) Hopefully, this is not a big problem, but let's see. 2. I know this is [still] stupid now; but any suggestions one how to symlink /dev/iio:device3 -> /dev/iio/device3/buffer0 ? Regarding this one, I may try a few things, but any suggestion is welcome. Thanks Alex
