[lm-sensors] [RFC] Generic device detection in sensors-detect

[khali@linux-fr.org (Jean Delvare)]

Hi all,

Now that I'm done with all the cleanups in sensors-detect, I thought it
would be refreshing to go for some inovation. Two ideas came to my
mind, both related to generic device detection. So far, sensors-detect
is essentially a long list of known devices to look for on the target
system. I think we could go one step further, and try to detect chips
we don't know about yet.

1* PCI devices have a class field, which describes the main
functionality of the device. SMBus is one of the possible classes since
PCI 2.2. Most recent SMBus adapters have their class properly set to
0x0c05 (SMBus), with the notable exception of the VIA ones.

Thus my first idea is to look for such devices even if we don't know
about the exact model yet. Patch attached
(sensors-detect-generic-pci.patch), sample output follows:

  We can start with probing for (PCI) I2C or SMBus adapters.
  Do you want to probe now? (YES/no): 
  Probing for PCI bus adapters...
  Found unknown SMBus adapter 8086:2483 at 00:1f:3.

I'm not exactly satisfied with the implementation, but feel tree to
comment on the idea nevertheless. To try it out, apply the patch, then
in @pci_adapters, comment out the entry for your own SMBus adapter.

2* The interface to Super-I/O chips is mostly standard, so we should be
able to talk even to Super-I/O chips we don't specifically know about.
The logical device used for hardware monitoring differs from one chip
to the next, but a good half of the chips (Winbond, ITE and Fintek
ones) still use the legacy I/O address 0x290 for hardware monitoring.

Thus my second idea is to scan all the logical devices when we find an
unknown Super-I/O chip, and see if one is set to I/O address 0x290 or
nearby. If we find one, this means that this unknown Super-I/O chip
most certainly embeds hardware monitoring features, and we can tell
that the user. Patch attached (sensors-detect-generic-superio.patch),
sample output follows:

  Some Super I/O chips may also contain sensors. We have to write to
  standard I/O ports to probe them. This is usually safe.
  Do you want to scan for Super I/O sensors? (YES/no): 
  Probing for Super-I/O at 0x2e/0x2f
  Trying family `ITE'...                                      No
  Trying family `National Semiconductor'...                   No
  Trying family `SMSC'...                                     No
  Trying family `VIA/Winbond/Fintek'...                       No
  Probing for Super-I/O at 0x4e/0x4f
  Trying family `ITE'...                                      No
  Trying family `National Semiconductor'...                   No
  Trying family `SMSC'...                                     No
  Trying family `VIA/Winbond/Fintek'...                       Yes
  Found unknown chip with ID 0x0406
      (logical device 4 has address 0x295, could be sensors)

This patch is simple and clean, and I think could be applied as is. The
only change I might do is to only attempt a guess for the "ITE" and
"VIA/Winbond/Fintek" families, as we've never seen an SMSC or National
Semiconductor Super-I/O chip with hardware monitoring device at 0x290
anyway.

To try it out, apply the patch, then in @superio_ids, comment out the
entry for your own Super-I/O chip.

Testers and comments welcome. The goal of these changes is to make it
easier for us to investigate when users with brand new hardware report
"no sensors found".

-- 
Jean Delvare
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