From: coffin@VNET.IBM.COM
Date: Tue, 11 Jun 96 14:12:30 CDT
Subject: Item #362: ISA: ISA-PnP Unit Address Format

P1275 Openboot Working Group Proposal -- Proposal #:362 Ver 1.0

Title:          ISA-PnP Unit Address Format

Author:         R. T. Coffin

Date:           June 11, 1996

Ed/Tech:        Technical

Synopsis:       Need to have a unique unit address for ISA-PnP
                Multifunction Cards specified.

Doc & Version:  ISA/EISA/ISA-PnP binding, Version 0.2.

Problem:        Need to include the PnP Card Function Code in the unit
                address to address a multifunction adapter logical
                functions.

Proposal:

Need to modify the present definition of the Unit Address for PnP
Adapters defined in the ISA binding, Version 0.2.  For PnP Multifunction
Adapters, the Function Code should be included along with the other
information defined in the present PnP Unit Address.  A suggested format
for the new unit address follows:

I) Unit Address for ISA-PnP Adapter

bits (msb) 3322 2222 2222 1111 1111 1100 0000 0000
           1098 7654 3210 9876 5432 1098 7654 3210

phys.hi    1vvv vvvv vvvv vvvv pppp pppp pppp pppp
phys.mid   1000 0000 0000 0000 ffff ffff ffff ffff
phys.lo    ssss ssss ssss ssss ssss ssss ssss ssss

  where:

phys.hi;   v=vendor number, p=product ID and the msb bit = 1 for a PnP
           Unit Address

phys.mid   f=function code and msb bit = 1 for a multifunction PnP card

phys.lo    s=serial number

For an ISA-PnP Adapter, "#address-cells" would be 3, as defined by the
parent node.  For this case, change bus name to PnP Bus (Help
distinguish difference between 'legacy' ISA Cards and 'PnP Cards).

For 'legacy' ISA cards, the "#address-cells" would remain at 2.  For
this case, leave bus name as 'ISA' Bus.  Therefore, a system could
support just 'legacy' ISA Cards with a "#address-cells" equal to 2, or
indicate ISA-PnP Cards with a "#address-cells" equal to 3.

II)  Unit Address Text Representation

ISA 'legacy' Cards would remain as defined in the ISA binding.

ISA-PnP Cards Unit Address Text Representation would be:

 @VVV, pppp, ssssssss, fff

  where:

   'VVV' ASCII Vendor ID, upper case hexadecimal characters
   'pppp' Product ID, lower case hexadecimal characters with leading
          zeroes suppressed
   'ssssssss', Serial Number, lower case hexadecimal characters with
               leading zeroes suppressed
   'fff', Function Number(Logical Device Number), 0 ... (n-1), lower
          case hexadecimal characters with leading zeroes suppressed

Byte order to be maintained as specified in 'plug-n-play' specification.

[ P1275 Item #362 -- Received: Tue Jun 11 12:22:16 PDT 1996 ]