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>

arch/x86/mm/ioremap.c

@@ -126,6 +126,8 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
 			return NULL;
 	}
 
+	WARN_ON_ONCE(page_is_ram(pfn));
+
 	switch (mode) {
 	case IOR_MODE_UNCACHED:
 	default:

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);
 }
 

drivers/char/agp/ati-agp.c

@@ -60,18 +60,9 @@ static int ati_create_page_map(struct ati_page_map *page_map)
 	if (page_map->real == NULL)
 		return -ENOMEM;
 
-	SetPageReserved(virt_to_page(page_map->real));
+	set_memory_uc(page_map->real, 1);
 	err = map_page_into_agp(virt_to_page(page_map->real));
-	page_map->remapped = ioremap_nocache(virt_to_gart(page_map->real),
-					    PAGE_SIZE);
-	if (page_map->remapped == NULL || err) {
-		ClearPageReserved(virt_to_page(page_map->real));
-		free_page((unsigned long) page_map->real);
-		page_map->real = NULL;
-		return -ENOMEM;
-	}
-	/*CACHE_FLUSH();*/
-	global_cache_flush();
+	page_map->remapped = page_map->real;
 
 	for (i = 0; i < PAGE_SIZE / sizeof(unsigned long); i++) {
 		writel(agp_bridge->scratch_page, page_map->remapped+i);
@@ -85,8 +76,7 @@ static int ati_create_page_map(struct ati_page_map *page_map)
 static void ati_free_page_map(struct ati_page_map *page_map)
 {
 	unmap_page_from_agp(virt_to_page(page_map->real));
-	iounmap(page_map->remapped);
-	ClearPageReserved(virt_to_page(page_map->real));
+	set_memory_wb(page_map->real, 1);
 	free_page((unsigned long) page_map->real);
 }
 

drivers/char/agp/generic.c

@@ -932,9 +932,14 @@ int agp_generic_create_gatt_table(struct agp_bridge_data *bridge)
 	agp_gatt_table = (void *)table;
 
 	bridge->driver->cache_flush();
+#ifdef CONFIG_X86
+	set_memory_uc((unsigned long)table, 1 << page_order);
+	bridge->gatt_table = (void *)table;
+#else
 	bridge->gatt_table = ioremap_nocache(virt_to_gart(table),
 					(PAGE_SIZE * (1 << page_order)));
 	bridge->driver->cache_flush();
+#endif
 
 	if (bridge->gatt_table == NULL) {
 		for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
@@ -991,7 +996,11 @@ int agp_generic_free_gatt_table(struct agp_bridge_data *bridge)
 	 * called, then all agp memory is deallocated and removed
 	 * from the table. */
 
+#ifdef CONFIG_X86
+	set_memory_wb((unsigned long)bridge->gatt_table, 1 << page_order);
+#else
 	iounmap(bridge->gatt_table);
+#endif
 	table = (char *) bridge->gatt_table_real;
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 

drivers/char/agp/sworks-agp.c

@@ -52,28 +52,20 @@ static int serverworks_create_page_map(struct serverworks_page_map *page_map)
 	if (page_map->real == NULL) {
 		return -ENOMEM;
 	}
-	SetPageReserved(virt_to_page(page_map->real));
-	global_cache_flush();
-	page_map->remapped = ioremap_nocache(virt_to_gart(page_map->real),
-					    PAGE_SIZE);
-	if (page_map->remapped == NULL) {
-		ClearPageReserved(virt_to_page(page_map->real));
-		free_page((unsigned long) page_map->real);
-		page_map->real = NULL;
-		return -ENOMEM;
-	}
-	global_cache_flush();
+
+	set_memory_uc(page_map->real, 1);
+	page_map->remapped = page_map->real;
 
 	for (i = 0; i < PAGE_SIZE / sizeof(unsigned long); i++)
 		writel(agp_bridge->scratch_page, page_map->remapped+i);
+		/* Red Pen: Everyone else does pci posting flush here */
 
 	return 0;
 }
 
 static void serverworks_free_page_map(struct serverworks_page_map *page_map)
 {
-	iounmap(page_map->remapped);
-	ClearPageReserved(virt_to_page(page_map->real));
+	set_memory_wb(page_map->real, 1);
 	free_page((unsigned long) page_map->real);
 }