agp/intel: Add chipset flushing support for i8xx chipsets.

This is a bit of a large hammer but it makes sure the chipset is flushed
by writing out 1k of data to an uncached page. We may be able to get better
information in the future on how to this better.

Signed-off-by: Dave Airlie <[e-mail]>

drivers/char/agp/intel-agp.c

···
 	 * popup and for the GTT.
 	 */
 	int gtt_entries;			/* i830+ */
-	void __iomem *flush_page;
+	union {
+		void __iomem *i9xx_flush_page;
+		void *i8xx_flush_page;
+	};
+	struct page *i8xx_page;
 	struct resource ifp_resource;
 } intel_private;
 
···
 	intel_private.gtt_entries = gtt_entries;
 }
 
+static void intel_i830_fini_flush(void)
+{
+	kunmap(intel_private.i8xx_page);
+	intel_private.i8xx_flush_page = NULL;
+	unmap_page_from_agp(intel_private.i8xx_page);
+	flush_agp_mappings();
+
+	__free_page(intel_private.i8xx_page);
+}
+
+static void intel_i830_setup_flush(void)
+{
+
+	intel_private.i8xx_page = alloc_page(GFP_KERNEL | __GFP_ZERO | GFP_DMA32);
+	if (!intel_private.i8xx_page) {
+		return;
+	}
+
+	/* make page uncached */
+	map_page_into_agp(intel_private.i8xx_page);
+	flush_agp_mappings();
+
+	intel_private.i8xx_flush_page = kmap(intel_private.i8xx_page);
+	if (!intel_private.i8xx_flush_page)
+		intel_i830_fini_flush();
+}
+
+static void intel_i830_chipset_flush(struct agp_bridge_data *bridge)
+{
+	unsigned int *pg = intel_private.i8xx_flush_page;
+	int i;
+
+	for (i = 0; i < 256; i+=2)
+		*(pg + i) = i;
+	
+	wmb();
+}
+
 /* The intel i830 automatically initializes the agp aperture during POST.
  * Use the memory already set aside for in the GTT.
  */
···
 	}
 
 	global_cache_flush();
+
+	intel_i830_setup_flush();
 	return 0;
 }
 
···
 	ret = pci_bus_alloc_resource(agp_bridge->dev->bus, &intel_private.ifp_resource, PAGE_SIZE,
 				     PAGE_SIZE, PCIBIOS_MIN_MEM, 0,
 				     pcibios_align_resource, agp_bridge->dev);
-	if (ret != 0)
-		return ret;
 
-	printk("intel priv bus start %08lx\n", intel_private.ifp_resource.start);
-	return 0;
+	return ret;
 }
 
 static void intel_i915_setup_chipset_flush(void)
···
 
 		pci_write_config_dword(agp_bridge->dev, I965_IFPADDR + 4, (intel_private.ifp_resource.start >> 32));
 		pci_write_config_dword(agp_bridge->dev, I965_IFPADDR, (intel_private.ifp_resource.start & 0xffffffff) | 0x1);
-		intel_private.flush_page = ioremap_nocache(intel_private.ifp_resource.start, PAGE_SIZE);
 	} else {
 		u64 l64;
 		
···
 		intel_private.ifp_resource.end = l64 + PAGE_SIZE;
 		ret = request_resource(&iomem_resource, &intel_private.ifp_resource);
 		if (!ret) {
-			intel_private.ifp_resource.start = 0;
-			printk("Failed inserting resource into tree\n");
+			printk("Failed inserting resource into tree - continuing\n");
 		}
+	}
+}
+
+static void intel_i9xx_setup_flush(void)
+{
+	/* setup a resource for this object */
+	memset(&intel_private.ifp_resource, 0, sizeof(intel_private.ifp_resource));
+
+	intel_private.ifp_resource.name = "Intel Flush Page";
+	intel_private.ifp_resource.flags = IORESOURCE_MEM;
+
+	/* Setup chipset flush for 915 */
+	if (IS_I965 || IS_G33) {
+		intel_i965_g33_setup_chipset_flush();
+	} else {
+		intel_i915_setup_chipset_flush();
+	}
+
+	if (intel_private.ifp_resource.start) {
+		intel_private.i9xx_flush_page = ioremap_nocache(intel_private.ifp_resource.start, PAGE_SIZE);
+		if (!intel_private.i9xx_flush_page)
+			printk("unable to ioremap flush  page - no chipset flushing");
 	}
 }
 
···
 
 	global_cache_flush();
 
-	/* setup a resource for this object */
-	memset(&intel_private.ifp_resource, 0, sizeof(intel_private.ifp_resource));
-
-	intel_private.ifp_resource.name = "Intel Flush Page";
-	intel_private.ifp_resource.flags = IORESOURCE_MEM;
-
-	/* Setup chipset flush for 915 */
-	if (IS_I965 || IS_G33) {
-		intel_i965_g33_setup_chipset_flush();
-	} else {
-		intel_i915_setup_chipset_flush();
-	}
-
-	if (intel_private.ifp_resource.start) {
-		intel_private.flush_page = ioremap_nocache(intel_private.ifp_resource.start, PAGE_SIZE);
-		if (!intel_private.flush_page)
-			printk("unable to ioremap flush  page - no chipset flushing");
-	}
+	intel_i9xx_setup_flush();
 	
 	return 0;
 }
 
 static void intel_i915_cleanup(void)
 {
-	if (intel_private.flush_page)
-		iounmap(intel_private.flush_page);
+	if (intel_private.i9xx_flush_page)
+		iounmap(intel_private.i9xx_flush_page);
 	iounmap(intel_private.gtt);
 	iounmap(intel_private.registers);
 }
 
 static void intel_i915_chipset_flush(struct agp_bridge_data *bridge)
 {
-	if (intel_private.flush_page)
-		writel(1, intel_private.flush_page);
+	if (intel_private.i9xx_flush_page)
+		writel(1, intel_private.i9xx_flush_page);
 }
 
 static int intel_i915_insert_entries(struct agp_memory *mem,off_t pg_start,
···
 	pci_write_config_byte(agp_bridge->dev, INTEL_I845_AGPM, temp2 | (1 << 1));
 	/* clear any possible error conditions */
 	pci_write_config_word(agp_bridge->dev, INTEL_I845_ERRSTS, 0x001c);
+
+	intel_i830_setup_flush();
 	return 0;
 }
 
···
 	.agp_alloc_page		= agp_generic_alloc_page,
 	.agp_destroy_page	= agp_generic_destroy_page,
 	.agp_type_to_mask_type  = intel_i830_type_to_mask_type,
+	.chipset_flush		= intel_i830_chipset_flush,
 };
 
 static const struct agp_bridge_driver intel_820_driver = {
···
 	.agp_alloc_page		= agp_generic_alloc_page,
 	.agp_destroy_page	= agp_generic_destroy_page,
 	.agp_type_to_mask_type  = agp_generic_type_to_mask_type,
+	.chipset_flush		= intel_i830_chipset_flush,
 };
 
 static const struct agp_bridge_driver intel_850_driver = {