From 884525655d07fdee9245716b998ecdc45cdd8007 Mon Sep 17 00:00:00 2001 From: Ivan Kokshaysky Date: Sun, 30 Mar 2008 19:50:14 +0400 Subject: 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 Cc: Linus Torvalds Cc: Gary Hade Signed-off-by: Greg Kroah-Hartman --- kernel/resource.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'kernel/resource.c') diff --git a/kernel/resource.c b/kernel/resource.c index 82aea814d40..cee12cc47ca 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. * -- cgit v1.2.3