PNP: convert resource options to single linked list

ISAPNP, PNPBIOS, and ACPI describe the "possible resource settings" of
a device, i.e., the possibilities an OS bus driver has when it assigns
I/O port, MMIO, and other resources to the device.

PNP used to maintain this "possible resource setting" information in
one independent option structure and a list of dependent option
structures for each device.  Each of these option structures had lists
of I/O, memory, IRQ, and DMA resources, for example:

  dev
    independent options
      ind-io0  -> ind-io1  ...
      ind-mem0 -> ind-mem1 ...
      ...
    dependent option set 0
      dep0-io0  -> dep0-io1  ...
      dep0-mem0 -> dep0-mem1 ...
      ...
    dependent option set 1
      dep1-io0  -> dep1-io1  ...
      dep1-mem0 -> dep1-mem1 ...
      ...
    ...

This data structure was designed for ISAPNP, where the OS configures
device resource settings by writing directly to configuration
registers.  The OS can write the registers in arbitrary order much
like it writes PCI BARs.

However, for PNPBIOS and ACPI devices, the OS uses firmware interfaces
that perform device configuration, and it is important to pass the
desired settings to those interfaces in the correct order.  The OS
learns the correct order by using firmware interfaces that return the
"current resource settings" and "possible resource settings," but the
option structures above doesn't store the ordering information.

This patch replaces the independent and dependent lists with a single
list of options.  For example, a device might have possible resource
settings like this:

  dev
    options
      ind-io0 -> dep0-io0 -> dep1->io0 -> ind-io1 ...

All the possible settings are in the same list, in the order they
come from the firmware "possible resource settings" list.  Each entry
is tagged with an independent/dependent flag.  Dependent entries also
have a "set number" and an optional priority value.  All dependent
entries must be assigned from the same set.  For example, the OS can
use all the entries from dependent set 0, or all the entries from
dependent set 1, but it cannot mix entries from set 0 with entries
from set 1.

Prior to this patch PNP didn't keep track of the order of this list,
and it assigned all independent options first, then all dependent
ones.  Using the example above, that resulted in a "desired
configuration" list like this:

  ind->io0 -> ind->io1 -> depN-io0 ...

instead of the list the firmware expects, which looks like this:

  ind->io0 -> depN-io0 -> ind-io1 ...

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/pnp.h b/include/linux/pnp.h
index 785126ffcc11..1ce54b63085d 100644
--- a/include/linux/pnp.h
+++ b/include/linux/pnp.h
@@ -1,6 +1,8 @@
 /*
  * Linux Plug and Play Support
  * Copyright by Adam Belay <ambx1@neo.rr.com>
+ * Copyright (C) 2008 Hewlett-Packard Development Company, L.P.
+ *      Bjorn Helgaas <bjorn.helgaas@hp.com>
  */
 
 #ifndef _LINUX_PNP_H
@@ -249,9 +251,9 @@ struct pnp_dev {
 
         int active;
         int capabilities;
-        struct pnp_option *independent;
-        struct pnp_option *dependent;
+        unsigned int num_dependent_sets;
         struct list_head resources;
+        struct list_head options;
 
         char name[PNP_NAME_LEN];        /* contains a human-readable name */
         int flags;                      /* used by protocols */