[ENHANCEMENT] NPEM/DSM kernel driver support

[mtkaczyk]

Description

The feature has been recently accepted in kernel, it is a time to implement support in library, ledctl and ledmon.
https://lore.kernel.org/linux-pci/Ztlt_ZUy1EH1VQgC@smile.fi.intel.com/T/#t

Reason

Current NPEM implementation is accessing PCI config space directly which is not compatible with kernel lockdown feature.

Environment

N/A

[tasleson]

@mtkaczyk @mku514k

I may have some hardware to develop this, but not totally sure.

When I examine /sys/class/leds

I'm seeing:

# ls
0000:69:00.0:enclosure:locate  0000:6e:00.0:enclosure:locate  0000:e9:00.0:enclosure:locate  0000:ee:00.0:enclosure:locate
0000:6a:00.0:enclosure:locate  0000:6f:00.0:enclosure:locate  0000:ea:00.0:enclosure:locate  0000:f1:00.0:enclosure:locate
0000:6b:00.0:enclosure:locate  0000:70:00.0:enclosure:locate  0000:eb:00.0:enclosure:locate  0000:f2:00.0:enclosure:locate
0000:6c:00.0:enclosure:locate  0000:e7:00.0:enclosure:locate  0000:ec:00.0:enclosure:locate  0000:f3:00.0:enclosure:locate
0000:6d:00.0:enclosure:locate  0000:e8:00.0:enclosure:locate  0000:ed:00.0:enclosure:locate  0000:f4:00.0:enclosure:locate

For an individual enclosure dir I see:

# ls -lh
total 0
-rw-r--r--. 1 root root 4.0K Sep  3 17:29 brightness
lrwxrwxrwx. 1 root root    0 Sep  3 17:20 device -> ../../../0000:69:00.0
-r--r--r--. 1 root root 4.0K Sep  3 17:20 max_brightness
drwxr-xr-x. 2 root root    0 Sep  3 17:20 power
lrwxrwxrwx. 1 root root    0 Sep  3 17:20 subsystem -> ../../../../../../../../../../class/leds
-rw-r--r--. 1 root root    0 Sep  3 17:20 trigger
-rw-r--r--. 1 root root 4.0K Sep  3 17:20 uevent

I ran ledctl version 1.1.0 on the system and I see the following

# ledctl --list-controllers
/dev/shm/ledmon.conf: does not exist, using global config file
/etc/ledmon.conf: does not exist, using built-in defaults
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:04.0/0000:6a:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:04.0/0000:ef:00.0/0000:f0:14.0/0000:f2:00.0 (Dell SSD)
/sys/devices/pci0000:00/0000:00:17.0 (AHCI)
/sys/devices/pci0000:00/0000:00:11.5 (AHCI)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:04.0/0000:ef:00.0/0000:f0:10.0/0000:f1:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:18.0/0000:6f:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:1c.0/0000:ee:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:14.0/0000:6e:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:1c.0/0000:70:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:18.0/0000:ed:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:10.0/0000:6d:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:14.0/0000:ec:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:08.0/0000:e9:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:0c.0/0000:6c:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:04.0/0000:ef:00.0/0000:f0:1c.0/0000:f4:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:00.0/0000:69:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:10.0/0000:eb:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:04.0/0000:e8:00.0 (Dell SSD)
/sys/devices/pci0000:64/0000:64:02.0/0000:65:00.0/0000:66:00.0/0000:67:00.0/0000:68:08.0/0000:6b:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:04.0/0000:ef:00.0/0000:f0:18.0/0000:f3:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:0c.0/0000:ea:00.0 (Dell SSD)
/sys/devices/pci0000:e2/0000:e2:02.0/0000:e3:00.0/0000:e4:00.0/0000:e5:00.0/0000:e6:00.0/0000:e7:00.0 (Dell SSD)

But I'm unable to list slots using "Dell SSD" or any other standard controller type.

From what I see in the kernel docs I think this indicates that each of these LEDs has the ability to "locate", nothing else?

At the moment I'm a little confused about what happens when an indication changes? I'm thinking then the sysfs "locate" will change to some other indication? I'm not sure if locate also indicates ok.

I'm also under the impression that moving forward, the existing NPEM support will all move to this new sysfs for kernels 6.12 and later?

Thanks for any info!

[mtkaczyk]

HI @tasleson
Me and @mku514k are no longer working on this. I also don't think Intel is interested in developing it. If you would like to try.. fell free.

From what I see in the kernel docs I think this indicates that each of these LEDs has the ability to "locate", nothing else?

Yes, and according to spec 4 indications are mandatory so your hardware is not spec compliant.

At the moment I'm a little confused about what happens when an indication changes? I'm thinking then the sysfs "locate" will change to some other indication? I'm not sure if locate also indicates ok.

About changing indication:
See: https://elixir.bootlin.com/linux/v6.16.4/source/drivers/pci/npem.c#L246
Specification is not strict so the behavior depends on implementation in hardware.
Locate and ok are different indications. Each indication name has corresponding bit NPEM register.

I'm also under the impression that moving forward, the existing NPEM support will all move to this new sysfs for kernels 6.12 and later?

Yes, that was a plan however it is no longer valid. Kernel interface should be a default way because direct access to PCI space is not needed and it is compatible with kernel lockdown.

[stuarthayes]

Hello! A couple of comments...

According to NPEM spec, there are 4 indications that are required, but in the _DSM spec, there is no such requirement. Many Dell servers support the _DSM interface, and wouldn't be out of spec to support only the "locate" indicator.

The "Dell SSD" type support in ledmon uses an IPMI interface, not the NPEM or _DSM interface. This IPMI interface is being phased out in favor of the _DSM interface, so Dell has an interest in support for the new NPEM/_DSM interface that @mtkaczyk mentioned above.

[mtkaczyk]

PR: #270