fix historic ioremap() abuse in AGP

Several AGP drivers right now use ioremap_nocache() on kernel ram in order
to turn a page of regular memory uncached.

There are two problems with this:

    1) This is a total nightmare for the ioremap() implementation to keep
       various mappings of the same page coherent.

    2) It's a total nightmare for the AGP code since it adds a ton of
       complexity in terms of keeping track of 2 different pointers to
       the same thing, in terms of error handling etc etc.

This patch fixes this by making the AGP drivers use the new
set_memory_XX APIs instead.

Note: amd-k7-agp.c is built on Alpha too, and generic.c is built
on ia64 as well, which do not yet have the set_memory_*() APIs,
so for them some we have a few ugly #ifdefs - hopefully they'll
be fixed soon.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Dave Airlie <airlied@linux.ie>

drivers/char/agp/amd-k7-agp.c

@@ -41,6 +41,7 @@ static int amd_create_page_map(struct amd_page_map *page_map)
 	if (page_map->real == NULL)
 		return -ENOMEM;
 
+#ifndef CONFIG_X86
 	SetPageReserved(virt_to_page(page_map->real));
 	global_cache_flush();
 	page_map->remapped = ioremap_nocache(virt_to_gart(page_map->real),
@@ -52,6 +53,10 @@ static int amd_create_page_map(struct amd_page_map *page_map)
 		return -ENOMEM;
 	}
 	global_cache_flush();
+#else
+	set_memory_uc(page_map->real, 1);
+	page_map->remapped = page_map->real;
+#endif
 
 	for (i = 0; i < PAGE_SIZE / sizeof(unsigned long); i++) {
 		writel(agp_bridge->scratch_page, page_map->remapped+i);
@@ -63,8 +68,12 @@ static int amd_create_page_map(struct amd_page_map *page_map)
 
 static void amd_free_page_map(struct amd_page_map *page_map)
 {
+#ifndef CONFIG_X86
 	iounmap(page_map->remapped);
 	ClearPageReserved(virt_to_page(page_map->real));
+#else
+	set_memory_wb(page_map->real, 1);
+#endif
 	free_page((unsigned long) page_map->real);
 }