i386/100142: /dev/smb0 device not available on systems with Intel PiiX4

[Intron]

Arthur Hartwig wrote:

> 
>>Number:         100142
>>Category:       i386
>>Synopsis:       /dev/smb0 device not available on systems with Intel PiiX4
>>Confidential:   no
>>Severity:       non-critical
>>Priority:       medium
>>Responsible:    freebsd-i386
>>State:          open
>>Quarter:        
>>Keywords:       
>>Date-Required:
>>Class:          sw-bug
>>Submitter-Id:   current-users
>>Arrival-Date:   Wed Jul 12 05:10:14 GMT 2006
>>Closed-Date:
>>Last-Modified:
>>Originator:     Arthur Hartwig
>>Release:        6.0
>>Organization:
> Nokia
>>Environment:
> FreeBSD oz-net-10.nes.nokia.com 6.0-RELEASE FreeBSD 6.0-RELEASE #3: Wed Mar  1 10:46:02 EST 2006     hartwig at oz-net-10.nes.nokia.com:/usr/src/sys/i386/compile/oz-net-10  i386
>>Description:
> System configured with devices intppm, smbb and smbus.
> 
> On startup smbus1 is reported but no smbus0 is reported. There is no file /dev/smb0
> 
> In sys/pci/intpm.c intpm_attach() executes 
>     smbinterface = device_add_child(dev, ""intsmb", unit); 
> 
>     device_probe_and_attach(smbinterface);
> 
> device_probe_and_attach() calls device_probe_child() which ends us calling intsmb_probe() twice, once when search for the best matching driver and again, because intsmb_probe() returns BUS_PROBE_DEFAULT, immediately after the comment "Call the probe method again to make sure we have the right description."
> 
> Calling intsmb_probe() twice results in creation of devices smbus0 (on the first call to intsmb_probe) and smbus1 (on the second call to intsmb_probe). The second probe call results in When intsmb_attach(0 is called, sc->smbus contains a pointer to a device structure for smbus1 and consequently smbus1 is reported in the startup.
> 
> 
>>How-To-Repeat:
> 
>>Fix:
> Suggested fix:
> In sys/pci/intpm move
>         sc->smbus=device_add_child(dev, "smbus", -1);
>         if (!sc->smbus)
>                 return (EINVAL);    /* XXX don't know what to return else */
> 
> from intsmb_probe() to intsmb_attach()
> 
> The suggested fix mirrors more closely the code in sys/pci/viapm.c and sys/pci/amdpm.c
> 
> 
> 
>>Release-Note:
>>Audit-Trail:
>>Unformatted:
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Please try the following commands:

kldload smbus
kldload ichsmb
kldload smb

Then, I can access SMBUS via /dev/smb0.
The kernel messages are:

ichsmb0: <SMBus controller> port 0xc400-0xc41f irq 19 at device 31.3 on pci0
ichsmb0: [GIANT-LOCKED]
smbus0: <System Management Bus> on ichsmb0
smb0: <SMBus generic I/O> on smbus0

The chipset on my motherboard is Intel 82915G-82801FB(ICH6).

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