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authorIvan Kokshaysky <ink@jurassic.park.msu.ru>2008-03-30 15:50:14 (GMT)
committerGreg Kroah-Hartman <gregkh@suse.de>2008-04-21 04:47:08 (GMT)
commit884525655d07fdee9245716b998ecdc45cdd8007 (patch)
tree975cbf2b5079430240d3496323df1a266be95d27 /kernel/resource.c
parentd75b305295c38ba9610ff3b2200f7d1989dc55fd (diff)
downloadlinux-884525655d07fdee9245716b998ecdc45cdd8007.tar.xz
PCI: clean up resource alignment management
Done per Linus' request and suggestions. Linus has explained that better than I'll be able to explain: On Thu, Mar 27, 2008 at 10:12:10AM -0700, Linus Torvalds wrote: > Actually, before we go any further, there might be a less intrusive > alternative: add just a couple of flags to the resource flags field (we > still have something like 8 unused bits on 32-bit), and use those to > implement a generic "resource_alignment()" routine. > > Two flags would do it: > > - IORESOURCE_SIZEALIGN: size indicates alignment (regular PCI device > resources) > > - IORESOURCE_STARTALIGN: start field is alignment (PCI bus resources > during probing) > > and then the case of both flags zero (or both bits set) would actually be > "invalid", and we would also clear the IORESOURCE_STARTALIGN flag when we > actually allocate the resource (so that we don't use the "start" field as > alignment incorrectly when it no longer indicates alignment). > > That wouldn't be totally generic, but it would have the nice property of > automatically at least add sanity checking for that whole "res->start has > the odd meaning of 'alignment' during probing" and remove the need for a > new field, and it would allow us to have a generic "resource_alignment()" > routine that just gets a resource pointer. Besides, I removed IORESOURCE_BUS_HAS_VGA flag which was unused for ages. Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Gary Hade <garyhade@us.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/resource.c')
-rw-r--r--kernel/resource.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 82aea81..cee12cc 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -486,6 +486,24 @@ int adjust_resource(struct resource *res, resource_size_t start, resource_size_t
EXPORT_SYMBOL(adjust_resource);
+/**
+ * resource_alignment - calculate resource's alignment
+ * @res: resource pointer
+ *
+ * Returns alignment on success, 0 (invalid alignment) on failure.
+ */
+resource_size_t resource_alignment(struct resource *res)
+{
+ switch (res->flags & (IORESOURCE_SIZEALIGN | IORESOURCE_STARTALIGN)) {
+ case IORESOURCE_SIZEALIGN:
+ return res->end - res->start + 1;
+ case IORESOURCE_STARTALIGN:
+ return res->start;
+ default:
+ return 0;
+ }
+}
+
/*
* This is compatibility stuff for IO resources.
*