Associate physical device with device name

Associate physical device with device name

[Jimmy Assarsson]

Hi,

We would like to be able to associate physical (Kvaser) USB devices with
their device names (can0 etc.).
The interface's EAN (article number) combined with serial number, form a
unique identifier.

It is not possible to do this from the USB descriptor. Since the serial
number is not provided in the USB descriptor. And the same PID is reused
for multiple EAN numbers. It is preferable with a solution that is
independent of interface type (USB etc.), since we may support other
devices in the future.

This is somewhat similar to '"user id" for can usb adapters',
https://marc.info/?l=linux-can&m=146565019622100

What is the preferable way of solving this kind of problem? Is sysfs
suitable?


Regards,
Jimmy

Re: Associate physical device with device name

[Jimmy Assarsson]

On 2018-01-26 15:38, Jimmy Assarsson wrote:
> We would like to be able to associate physical (Kvaser) USB devices with
> their device names (can0 etc.).
> The interface's EAN (article number) combined with serial number, form a
> unique identifier.
> 
> It is not possible to do this from the USB descriptor. Since the serial
> number is not provided in the USB descriptor. And the same PID is reused
> for multiple EAN numbers. It is preferable with a solution that is
> independent of interface type (USB etc.), since we may support other
> devices in the future.
> 
> This is somewhat similar to '"user id" for can usb adapters',
> https://marc.info/?l=linux-can&m=146565019622100
> 
> What is the preferable way of solving this kind of problem? Is sysfs
> suitable?

No suggestions or opinions on this?

Regards,
Jimmy

Re: Associate physical device with device name

[Marc Kleine-Budde]

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On 01/26/2018 03:38 PM, Jimmy Assarsson wrote:
> We would like to be able to associate physical (Kvaser) USB devices with
> their device names (can0 etc.).
> The interface's EAN (article number) combined with serial number, form a
> unique identifier.
> 
> It is not possible to do this from the USB descriptor. Since the serial
> number is not provided in the USB descriptor. And the same PID is reused
> for multiple EAN numbers. It is preferable with a solution that is
> independent of interface type (USB etc.), since we may support other
> devices in the future.
> 
> This is somewhat similar to '"user id" for can usb adapters',
> https://marc.info/?l=linux-can&m=146565019622100
> 
> What is the preferable way of solving this kind of problem? Is sysfs
> suitable?

Are your adaptors 100% idential? Then there is no way to tell them apart
in software. However you should be possible to write a custom udev rule
to rename the adapter depending on the physical USB-Port you are using.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: Associate physical device with device name

[Jimmy Assarsson]

On 2018-02-08 13:45, Marc Kleine-Budde wrote:
> On 01/26/2018 03:38 PM, Jimmy Assarsson wrote:
>> We would like to be able to associate physical (Kvaser) USB devices with
>> their device names (can0 etc.).
>> The interface's EAN (article number) combined with serial number, form a
>> unique identifier.
>>
>> It is not possible to do this from the USB descriptor. Since the serial
>> number is not provided in the USB descriptor. And the same PID is reused
>> for multiple EAN numbers. It is preferable with a solution that is
>> independent of interface type (USB etc.), since we may support other
>> devices in the future.
>>
>> This is somewhat similar to '"user id" for can usb adapters',
>> https://marc.info/?l=linux-can&m=146565019622100
>>
>> What is the preferable way of solving this kind of problem? Is sysfs
>> suitable?
> 
> Are your adaptors 100% idential? Then there is no way to tell them apart
> in software. However you should be possible to write a custom udev rule
> to rename the adapter depending on the physical USB-Port you are using.

No, they are not identical. The EAN and serial number is stored on the
device. Which makes a single device unique. It is possible to fetch
these from the device. And same applies to all Kvaser CAN interfaces,
regardless if they are connected via USB, PCI-express or ethernet.

Re: Associate physical device with device name

[Jimmy Assarsson]

On 2018-02-08 14:04, Jimmy Assarsson wrote:
> On 2018-02-08 13:45, Marc Kleine-Budde wrote:
>> On 01/26/2018 03:38 PM, Jimmy Assarsson wrote:
>>> We would like to be able to associate physical (Kvaser) USB devices with
>>> their device names (can0 etc.).
>>> The interface's EAN (article number) combined with serial number, form a
>>> unique identifier.
>>>
>>> It is not possible to do this from the USB descriptor. Since the serial
>>> number is not provided in the USB descriptor. And the same PID is reused
>>> for multiple EAN numbers. It is preferable with a solution that is
>>> independent of interface type (USB etc.), since we may support other
>>> devices in the future.
>>>
>>> This is somewhat similar to '"user id" for can usb adapters',
>>> https://marc.info/?l=linux-can&m=146565019622100
>>>
>>> What is the preferable way of solving this kind of problem? Is sysfs
>>> suitable?
>>
>> Are your adaptors 100% idential? Then there is no way to tell them apart
>> in software. However you should be possible to write a custom udev rule
>> to rename the adapter depending on the physical USB-Port you are using.
> 
> No, they are not identical. The EAN and serial number is stored on the
> device. Which makes a single device unique. It is possible to fetch
> these from the device. And same applies to all Kvaser CAN interfaces,
> regardless if they are connected via USB, PCI-express or ethernet.

Maybe the initial question was fuzzy. We want to achieve the following:
The user got two devices, one with SN (serial number) 5 and one with SN
6. The device with SN 5 is connected to CAN bus 'A' and the one with SN
6 is connected to CAN bus 'B'. The user connects the devices in
arbitrary order. And starts a user space application that should
communicate on CAN bus 'B'. The application should find and use the
netdev (can0 or can1) for the device with SN 6.

Re: Associate physical device with device name

[Marc Kleine-Budde]

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On 02/08/2018 02:04 PM, Jimmy Assarsson wrote:
> No, they are not identical. The EAN and serial number is stored on the
> device.

How to read them?

> Which makes a single device unique. It is possible to fetch these
> from the device. And same applies to all Kvaser CAN interfaces, 
> regardless if they are connected via USB, PCI-express or ethernet.
What's the output of the udev when using the proper path to your device?

"udevadm info --path=/devices/pci0000:00/0000:00:14.0/usb1/1-2/ -a"

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: Associate physical device with device name

[Jimmy Assarsson]

On 2018-02-09 11:47, Marc Kleine-Budde wrote:
> On 02/08/2018 02:04 PM, Jimmy Assarsson wrote:
>> No, they are not identical. The EAN and serial number is stored on the
>> device.
> 
> How to read them?

It is part of the "kvaser_msg_cardinfo" command, see
https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git/tree/drivers/net/can/usb/kvaser_usb.c#n198

>> Which makes a single device unique. It is possible to fetch these
>> from the device. And same applies to all Kvaser CAN interfaces,
>> regardless if they are connected via USB, PCI-express or ethernet.
> What's the output of the udev when using the proper path to your device?
> 
> "udevadm info --path=/devices/pci0000:00/0000:00:14.0/usb1/1-2/ -a"

All devices with the same EAN look identical, since we do not set serial
number in the USB descriptor.

The output from "udevadm info 
--path=/sys/devices/pci0000:00/0000:00:02.1/usb1/1-4/1-4.1/1-4.1:1.0 -a"

   looking at device 
'/devices/pci0000:00/0000:00:02.1/usb1/1-4/1-4.1/1-4.1:1.0':
     KERNEL=="1-4.1:1.0"
     SUBSYSTEM=="usb"
     DRIVER=="kvaser_usb"
     ATTR{authorized}=="1"
     ATTR{bAlternateSetting}==" 0"
     ATTR{bInterfaceClass}=="00"
     ATTR{bInterfaceNumber}=="00"
     ATTR{bInterfaceProtocol}=="00"
     ATTR{bInterfaceSubClass}=="00"
     ATTR{bNumEndpoints}=="02"
     ATTR{supports_autosuspend}=="0"

   looking at parent device 
'/devices/pci0000:00/0000:00:02.1/usb1/1-4/1-4.1':
     KERNELS=="1-4.1"
     SUBSYSTEMS=="usb"
     DRIVERS=="usb"
     ATTRS{authorized}=="1"
     ATTRS{avoid_reset_quirk}=="0"
     ATTRS{bConfigurationValue}=="1"
     ATTRS{bDeviceClass}=="ff"
     ATTRS{bDeviceProtocol}=="00"
     ATTRS{bDeviceSubClass}=="00"
     ATTRS{bMaxPacketSize0}=="64"
     ATTRS{bMaxPower}=="132mA"
     ATTRS{bNumConfigurations}=="1"
     ATTRS{bNumInterfaces}==" 1"
     ATTRS{bcdDevice}=="0001"
     ATTRS{bmAttributes}=="c0"
     ATTRS{busnum}=="1"
     ATTRS{configuration}==""
     ATTRS{devnum}=="26"
     ATTRS{devpath}=="4.1"
     ATTRS{idProduct}=="0123"
     ATTRS{idVendor}=="0bfd"
     ATTRS{ltm_capable}=="no"
     ATTRS{manufacturer}=="Kvaser AB"
     ATTRS{maxchild}=="0"
     ATTRS{product}=="Kvaser USBcan Light"
     ATTRS{quirks}=="0x0"
     ATTRS{removable}=="unknown"
     ATTRS{speed}=="480"
     ATTRS{urbnum}=="17"
     ATTRS{version}==" 2.00"

Re: Associate physical device with device name

[Marc Kleine-Budde]

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On 02/09/2018 12:21 PM, Jimmy Assarsson wrote:
>>> No, they are not identical. The EAN and serial number is stored on the
>>> device.
>>
>> How to read them?
> 
> It is part of the "kvaser_msg_cardinfo" command, see
> https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git/tree/drivers/net/can/usb/kvaser_usb.c#n198

ok

>>> Which makes a single device unique. It is possible to fetch these
>>> from the device. And same applies to all Kvaser CAN interfaces,
>>> regardless if they are connected via USB, PCI-express or ethernet.
>> What's the output of the udev when using the proper path to your device?
>>
>> "udevadm info --path=/devices/pci0000:00/0000:00:14.0/usb1/1-2/ -a"
> 
> All devices with the same EAN look identical, since we do not set serial
> number in the USB descriptor.

That should be done on the next FW revision.

Ok - I see two possibilities.

1) sysfs file
Add a file to sysfs that contains the serial number, see:
http://lxr.bootlin.com/linux/latest/source/drivers/net/can/softing/softing_main.c#L718

2) ethtool eeprom
You can export the serial number via ethtool's dump eeprom functionality.

Better try 1).

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: Associate physical device with device name

[Jimmy Assarsson]

On 2018-02-09 14:24, Marc Kleine-Budde wrote:
> On 02/09/2018 12:21 PM, Jimmy Assarsson wrote:
>> All devices with the same EAN look identical, since we do not set serial
>> number in the USB descriptor.
> 
> That should be done on the next FW revision.

It is left out on purpose. I don't remember the details, but it had
something to do with Windows reinstalling the driver whenever a device
with different serial number is connected to the same USB port.

> Ok - I see two possibilities.
> 
> 1) sysfs file
> Add a file to sysfs that contains the serial number, see:
> http://lxr.bootlin.com/linux/latest/source/drivers/net/can/softing/softing_main.c#L718
> 
> 2) ethtool eeprom
> You can export the serial number via ethtool's dump eeprom functionality.
> 
> Better try 1).

Great :) Will try this next week.
Thanks!

Re: Associate physical device with device name

[Oliver Hartkopp]

On 02/09/2018 04:35 PM, Jimmy Assarsson wrote:
> On 2018-02-09 14:24, Marc Kleine-Budde wrote:
>> On 02/09/2018 12:21 PM, Jimmy Assarsson wrote:
>>> All devices with the same EAN look identical, since we do not set serial
>>> number in the USB descriptor.
>>
>> That should be done on the next FW revision.
> 
> It is left out on purpose. I don't remember the details, but it had
> something to do with Windows reinstalling the driver whenever a device
> with different serial number is connected to the same USB port.
> 
>> Ok - I see two possibilities.
>>
>> 1) sysfs file
>> Add a file to sysfs that contains the serial number, see:
>> http://lxr.bootlin.com/linux/latest/source/drivers/net/can/softing/softing_main.c#L718 
>>
>>
>> 2) ethtool eeprom
>> You can export the serial number via ethtool's dump eeprom functionality.
>>
>> Better try 1).
> 
> Great :) Will try this next week.

Would it make sense to provide a common sysfs infrastructure in

	linux/drivers/net/can/dev.c

to populate

	/sys/class/net/<can-interface-name>/<serial-num-whatever>

instead of maintaining this stuff in each single driver?

We have this requirement in the softing/kvaser/peak adapters so far.

We could provide some pointer in struct can_priv which points to a 
struct which contains the sysfs content - or something like this.

Any thoughts?

Best,
Oliver

Re: Associate physical device with device name

[Kurt Van Dijck]

Beware that you should have added the sysfs property before you register the can device. Doing it after may be too late since udev is reading the properties already.
I remember that netdev's can add a limited # groups, else you add the serial to de device, not the netdev.
Kurt

On 9 February 2018 18:09:36 CET, Oliver Hartkopp <socketcan@hartkopp.net> wrote:
>
>
>On 02/09/2018 04:35 PM, Jimmy Assarsson wrote:
>> On 2018-02-09 14:24, Marc Kleine-Budde wrote:
>>> On 02/09/2018 12:21 PM, Jimmy Assarsson wrote:
>>>> All devices with the same EAN look identical, since we do not set
>serial
>>>> number in the USB descriptor.
>>>
>>> That should be done on the next FW revision.
>> 
>> It is left out on purpose. I don't remember the details, but it had
>> something to do with Windows reinstalling the driver whenever a
>device
>> with different serial number is connected to the same USB port.
>> 
>>> Ok - I see two possibilities.
>>>
>>> 1) sysfs file
>>> Add a file to sysfs that contains the serial number, see:
>>>
>http://lxr.bootlin.com/linux/latest/source/drivers/net/can/softing/softing_main.c#L718
>
>>>
>>>
>>> 2) ethtool eeprom
>>> You can export the serial number via ethtool's dump eeprom
>functionality.
>>>
>>> Better try 1).
>> 
>> Great :) Will try this next week.
>
>Would it make sense to provide a common sysfs infrastructure in
>
>	linux/drivers/net/can/dev.c
>
>to populate
>
>	/sys/class/net/<can-interface-name>/<serial-num-whatever>
>
>instead of maintaining this stuff in each single driver?
>
>We have this requirement in the softing/kvaser/peak adapters so far.
>
>We could provide some pointer in struct can_priv which points to a 
>struct which contains the sysfs content - or something like this.
>
>Any thoughts?
>
>Best,
>Oliver
>
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Re: Associate physical device with device name

[André Hartmann]

Hi Oliver,

Am 09.02.2018 um 18:09 schrieb Oliver Hartkopp:
> 
> 
> On 02/09/2018 04:35 PM, Jimmy Assarsson wrote:
>> On 2018-02-09 14:24, Marc Kleine-Budde wrote:
>>> On 02/09/2018 12:21 PM, Jimmy Assarsson wrote:
>>>> All devices with the same EAN look identical, since we do not set 
>>>> serial
>>>> number in the USB descriptor.
>>>
>>> That should be done on the next FW revision.
>>
>> It is left out on purpose. I don't remember the details, but it had
>> something to do with Windows reinstalling the driver whenever a device
>> with different serial number is connected to the same USB port.
>>
>>> Ok - I see two possibilities.
>>>
>>> 1) sysfs file
>>> Add a file to sysfs that contains the serial number, see:
>>> http://lxr.bootlin.com/linux/latest/source/drivers/net/can/softing/softing_main.c#L718 
>>>
>>>
>>> 2) ethtool eeprom
>>> You can export the serial number via ethtool's dump eeprom 
>>> functionality.
>>>
>>> Better try 1).
>>
>> Great :) Will try this next week.
> 
> Would it make sense to provide a common sysfs infrastructure in
> 
>      linux/drivers/net/can/dev.c
> 
> to populate
> 
>      /sys/class/net/<can-interface-name>/<serial-num-whatever>
> 
> instead of maintaining this stuff in each single driver?
> 
> We have this requirement in the softing/kvaser/peak adapters so far.
> 
> We could provide some pointer in struct can_priv which points to a 
> struct which contains the sysfs content - or something like this.

+1. A general solution to read a serial number from sysfs would be very 
welcome.

> Any thoughts?
> 
> Best,
> Oliver
> 
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