[AGPGART] Only enable isochronous transfers on AGP3.5 chipsets.

The standard says that 3.0 chipsets don't support these extensions.
Move the isoch stuff out into isoch.c leaving behind a shell for basic
AGP3.0 enabling (to be written).

drivers/char/agp/Makefile

-agpgart-y := backend.o frontend.o generic.o generic-3.0.o
+agpgart-y := backend.o frontend.o generic.o generic-3.0.o isoch.o
 
 obj-$(CONFIG_AGP)		+= agpgart.o
 obj-$(CONFIG_AGP_ALI)		+= ali-agp.o

drivers/char/agp/agp.h

@@ -390,7 +390,8 @@ void agp_free_key(int key);
 int agp_num_entries(void);
 u32 agp_collect_device_status(u32 mode, u32 command);
 void agp_device_command(u32 command, int agp_v3);
-int agp_3_0_node_enable(struct agp_bridge_data *bridge, u32 mode);
+int agp_3_0_enable(struct agp_bridge_data *bridge, u32 mode);
+int agp_3_5_enable(struct agp_bridge_data *bridge, u32 mode);
 void global_cache_flush(void);
 void get_agp_version(struct agp_bridge_data *bridge);
 

drivers/char/agp/generic.c

@@ -476,7 +476,10 @@ void agp_generic_enable(u32 mode)
 		pci_read_config_dword(agp_bridge->dev, agp_bridge->capndx + 0x4, &agp_3_0);
 		/* Check to see if we are operating in 3.0 mode */
 		if((agp_3_0 >> 3) & 0x1) {
-			agp_3_0_node_enable(agp_bridge, mode);
+			if (agp_bridge->minor_version >= 5)
+				agp_3_5_enable(agp_bridge, mode);
+			else
+				agp_3_5_enable(agp_bridge, mode);
 			return;
 		} else {
 			printk (KERN_INFO PFX "not in AGP 3.0 mode, falling back to 2.x\n");