Re: [PATCH] Add sysfs support to the IPMI driver

[Greg KH <greg@kroah.com>]

On Sun, Mar 13, 2005 at 04:59:14PM -0600, Corey Minyard wrote:
> Greg KH wrote:
> >On Sat, Mar 12, 2005 at 10:57:24PM -0600, Corey Minyard wrote:
> >>The IPMI driver has long needed to tie into the device model (and I've 
> >>long been hoping someone else would do it).  I finally gave up and spent 
> >>the time to learn how to do it.  I think this is right, it seems to work 
> >>on on my system.
> >
> >Looks good.  One minor question:
> >
> >>+
> >>+	snprintf(name, sizeof(name), "ipmi%d", if_num);
> >>+	class_simple_device_add(ipmi_class, dev, NULL, name);
> >
> >What do ipmi class devices live on?  pci devices?  i2c devices?
> >platform devices?  Or are they purely virtual things?
> >
> Good question.  I struggled with this for a little while and decided the 
> class interface was important to have in first and I'd figure out the 
> rest later.  They live in different places depending on the particular 
> low-level interface.  Some live on the I2C bus (and will show up there 
> in sysfs with the I2C driver).  Some live on the ISA bus, some are 
> memory-mapped, some are on the PCI bus (though there is not a driver for 
> PCI support yet), and some sit on the end of a serial port (driver is in 
> the works).  I know, it's a mess, but there's not much I can do about 
> these crazy hardware manufacturers.
> 
> I wasn't sure where to handle all this.  The I2C and PCI bus side of 
> things should be handled.  However, the others probably need to sit 
> someplace on a bus, right?  That should probably be handled in the 
> low-level code that actually knows where the hardware sits.

Well, how about handling the devices that already have a struct device
today (like the i2c and pci devices)?  Pass the pointer to that device
into your class_simple_device_add() call.  Then, work on figuring out
where your other devices live on some new bus later.

thanks,

greg k-h