[AGPGART] Clean up SiS648 workaround by giving it its own driver.

This uses the generic agp v3 support routines previously added.
It confines the 'pause after switching mode' hack to the sis driver.

Fixes http://bugme.osdl.org/show_bug.cgi?id=2327

drivers/char/agp/generic.c

@@ -524,14 +524,6 @@ void agp_device_command(u32 command, int agp_v3)
 		printk(KERN_INFO PFX "Putting AGP V%d device at %s into %dx mode\n",
 				agp_v3 ? 3 : 2, pci_name(device), mode);
 		pci_write_config_dword(device, agp + PCI_AGP_COMMAND, command);
-
-		/*
-		 * Work around SIS648/746 instability by delaying a bit.
-		 * This isn't a particularly nice solution, but in absense of
-		 * info from SiS, it's the best we can do.
-		 */
-		set_current_state(TASK_INTERRUPTIBLE);
-		schedule_timeout((HZ+99)/100); /* >= 1/100th of a second */
 	}
 }
 EXPORT_SYMBOL(agp_device_command);

drivers/char/agp/sis-agp.c

@@ -67,6 +67,42 @@ static void sis_cleanup(void)
 			      (previous_size->size_value & ~(0x03)));
 }
 
+static void sis_648_enable(u32 mode)
+{
+	struct pci_dev *device = NULL;
+	u32 command;
+	int rate;
+
+	printk(KERN_INFO PFX "Found an AGP %d.%d compliant device at %s.\n",
+		agp_bridge->major_version,
+		agp_bridge->minor_version,
+		agp_bridge->dev->slot_name);
+
+	pci_read_config_dword(agp_bridge->dev, agp_bridge->capndx + PCI_AGP_STATUS, &command);
+	command = agp_collect_device_status(mode, command);
+	command |= AGPSTAT_AGP_ENABLE;
+	rate = (command & 0x7) << 2;
+
+	while ((device = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, device)) != NULL) {
+		u8 agp = pci_find_capability(device, PCI_CAP_ID_AGP);
+		if (!agp)
+			continue;
+
+		printk(KERN_INFO PFX "Putting AGP V3 device at %s into %dx mode\n",
+			pci_name(device), rate);
+
+		pci_write_config_dword(device, agp + PCI_AGP_COMMAND, command);
+
+		if(device->device == PCI_DEVICE_ID_SI_648) {
+			// weird: on 648 and 648fx chipsets any rate change in the target command register
+			// triggers a 5ms screwup during which the master cannot be configured
+			printk(KERN_INFO PFX "sis 648 agp fix - giving bridge time to recover\n");
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			schedule_timeout (1+(HZ*10)/1000);
+		}
+	}
+}
+
 static struct aper_size_info_8 sis_generic_sizes[7] =
 {
 	{256, 65536, 6, 99},
@@ -182,6 +218,26 @@ static struct agp_device_ids sis_agp_device_ids[] __devinitdata =
 	{ }, /* dummy final entry, always present */
 };
 
+
+static void __devinit sis_get_driver(struct agp_bridge_data *bridge)
+{
+	if (bridge->dev->device == PCI_DEVICE_ID_SI_648) {
+		if (agp_bridge->major_version == 3 && agp_bridge->minor_version < 5) {
+			sis_driver.agp_enable=sis_648_enable;
+		} else {
+			sis_driver.agp_enable			= sis_648_enable;
+			sis_driver.aperture_sizes		= agp3_generic_sizes;
+			sis_driver.size_type			= U16_APER_SIZE;
+			sis_driver.num_aperture_sizes	= AGP_GENERIC_SIZES_ENTRIES;
+			sis_driver.configure			= agp3_generic_configure;
+			sis_driver.fetch_size			= agp3_generic_fetch_size;
+			sis_driver.cleanup				= agp3_generic_cleanup;
+			sis_driver.tlb_flush			= agp3_generic_tlbflush;
+		}
+	}
+}
+
+
 static int __devinit agp_sis_probe(struct pci_dev *pdev,
 				   const struct pci_device_id *ent)
 {
@@ -216,10 +272,11 @@ static int __devinit agp_sis_probe(struct pci_dev *pdev,
 	bridge->dev = pdev;
 	bridge->capndx = cap_ptr;
 
+	get_agp_version(bridge);
+
 	/* Fill in the mode register */
-	pci_read_config_dword(pdev,
-			bridge->capndx+PCI_AGP_STATUS,
-			&bridge->mode);
+	pci_read_config_dword(pdev, bridge->capndx+PCI_AGP_STATUS, &bridge->mode);
+	sis_get_driver(bridge);
 
 	pci_set_drvdata(pdev, bridge);
 	return agp_add_bridge(bridge);