patch-2.4.22 linux-2.4.22/arch/x86_64/kernel/aperture.c

• Lines: 240
• Date: 2003-08-25 04:44:40.000000000 -0700
• Orig file: linux-2.4.21/arch/x86_64/kernel/aperture.c
• Orig date: 2003-06-13 07:51:32.000000000 -0700

diff -urN linux-2.4.21/arch/x86_64/kernel/aperture.c linux-2.4.22/arch/x86_64/kernel/aperture.c
@@ -1,14 +1,14 @@
 /* 
  * Firmware replacement code.
  * 
- * Work around broken BIOSes that don't set an aperture. 
- * The IOMMU code needs an aperture even who no AGP is present in the system.
- * Map the aperture over some low memory.  This is cheaper than doing bounce 
- * buffering. The memory is lost. This is done at early boot because only
- * the bootmem allocator can allocate 32+MB. 
+ * Work around broken BIOSes that don't set an aperture or only set the
+ * aperture in the AGP bridge. 
+ * If all fails map the aperture over some low memory.  This is cheaper than 
+ * doing bounce buffering. The memory is lost. This is done at early boot 
+ * because only the bootmem allocator can allocate 32+MB. 
  * 
  * Copyright 2002 Andi Kleen, SuSE Labs.
- * $Id: aperture.c,v 1.4 2002/11/28 06:05:58 ak Exp $
+ * $Id: aperture.c,v 1.7 2003/08/01 03:36:18 ak Exp $
  */
 #include <linux/config.h>
 #include <linux/kernel.h>
@@ -17,6 +17,8 @@
 #include <linux/bootmem.h>
 #include <linux/mmzone.h>
 #include <linux/pci_ids.h>
+#include <linux/pci.h>
+#include <linux/bitops.h>
 #include <asm/e820.h>
 #include <asm/io.h>
 #include <asm/proto.h>
@@ -64,16 +66,130 @@
 	return (u32)__pa(p); 
 }
 
+static int __init aperture_valid(char *name, u64 aper_base, u32 aper_size) 
+{ 
+	if (!aper_base) 
+		return 0;
+	if (aper_size < 64*1024*1024) { 
+		printk("Aperture from %s too small (%d MB)\n", name, aper_size>>20); 
+		return 0;
+	}
+	if (aper_base + aper_size >= 0xffffffff) { 
+		printk("Aperture from %s beyond 4GB. Ignoring.\n",name);
+		return 0; 
+	}
+	if (e820_mapped(aper_base, aper_base + aper_size, E820_RAM)) {  
+		printk("Aperture from %s pointing to e820 RAM. Ignoring.\n",name);
+		return 0; 
+	} 
+	return 1;
+} 
+
+/* Find a PCI capability */ 
+static __u32 __init find_cap(int num, int slot, int func, int cap) 
+{ 
+	if (!(read_pci_config_16(num,slot,func,PCI_STATUS) & PCI_STATUS_CAP_LIST))
+		return 0;
+	u8 pos = read_pci_config_byte(num,slot,func,PCI_CAPABILITY_LIST);
+	int bytes;
+	for (bytes = 0; bytes < 48 && pos >= 0x40; bytes++) { 
+		pos &= ~3; 
+		u8 id = read_pci_config_byte(num,slot,func,pos+PCI_CAP_LIST_ID); 
+		if (id == 0xff)
+			break;
+		if (id == cap) 
+			return pos; 
+		pos = read_pci_config_byte(num,slot,func,pos+PCI_CAP_LIST_NEXT); 
+	} 
+	return 0;
+} 
+
+/* Read a standard AGPv3 bridge header */
+static __u32 __init read_agp(int num, int slot, int func, int cap, u32 *order)
+{ 
+	printk("AGP bridge at %02x:%02x:%02x\n", num, slot, func); 
+	u32 apsizereg = read_pci_config_16(num,slot,func, cap + 0x14);
+
+	if (apsizereg == 0xffffffff) {
+		printk("APSIZE in AGP bridge unreadable\n");
+		return 0;
+	}
+
+	u32 apsize = apsizereg & 0xfff;
+	/* Some BIOS use weird encodings not in the AGPv3 table. */
+	if (apsize & 0xff) 
+		apsize |= 0xf00; 
+	int nbits = hweight16(apsize);
+	*order = 7 - nbits;
+	if ((int)*order < 0) /* < 32MB */
+		*order = 0;
+	
+	u32 aper_low = read_pci_config(num,slot,func, 0x10); 
+	u32 aper_hi = read_pci_config(num,slot,func,0x14); 
+	u64 aper = (aper_low & ~((1<<22)-1)) | ((u64)aper_hi << 32); 
+
+	printk("Aperture from AGP @ %Lx size %u MB (APSIZE %x)\n", 
+	       aper, 32 << *order, apsizereg);
+
+	if (!aperture_valid("AGP bridge", aper, (32*1024*1024) << *order))
+	    return 0;
+	return (u32)aper; 
+} 
+
+/* Look for an AGP bridge. Windows only expects the aperture in the
+   AGP bridge and some BIOS forget to initialize the Northbridge too.
+   Work around this here. 
+
+   Do an PCI bus scan by hand because we're running before the PCI
+   subsystem. 
+
+   All K8 AGP bridges are AGPv3 compliant, so we can do this scan
+   generically. It's probably overkill to always scan all slots because
+   the AGP bridges should be always an own bus on the HT hierarchy, 
+   but do it here for future safety. */
+static __u32 __init search_agp_bridge(u32 *order, int *valid_agp)
+{
+	int num, slot, func;
+
+	/* Poor man's PCI discovery */
+	for (num = 0; num < 32; num++) { 
+		for (slot = 0; slot < 32; slot++) { 
+			for (func = 0; func < 8; func++) { 
+				u32 class, cap;
+				class = read_pci_config(num,slot,func,
+							PCI_CLASS_REVISION);
+				if (class == 0xffffffff)
+					break; 
+				
+				switch (class >> 16) { 
+				case PCI_CLASS_BRIDGE_HOST:
+				case PCI_CLASS_BRIDGE_OTHER: /* needed? */
+					/* AGP bridge? */
+					cap = find_cap(num,slot,func,PCI_CAP_ID_AGP);
+					if (!cap)
+						break;
+					*valid_agp = 1; 
+					return read_agp(num,slot,func,cap,order);
+				} 
+				
+				/* No multi-function device? */
+				u8 type = read_pci_config_byte(num,slot,func,
+							       PCI_HEADER_TYPE);
+				if (!(type & 0x80))
+					break;
+			} 
+		} 
+	}
+	printk("No AGP bridge found\n"); 
+	return 0;
+}
+
 void __init iommu_hole_init(void) 
 { 
 	int fix, num; 
-	u32 aper_size, aper_alloc, aper_order;
+	u32 aper_size, aper_alloc = 0, aper_order;
 	u64 aper_base; 
-
-	if (no_iommu)
-		return;
-	if (end_pfn < (0xffffffff>>PAGE_SHIFT) && !force_mmu) 
-		return;
+	int valid_agp = 0;
 
 	printk("Checking aperture...\n"); 
 
@@ -87,15 +203,13 @@
 		aper_base = read_pci_config(0, num, 3, 0x94) & 0x7fff;
 		aper_base <<= 25; 
 
-		printk("CPU %d: aperture @ %Lx size %u KB\n", num-24, 
-		       aper_base, aper_size>>10);
-		if (!aper_base || aper_base + aper_size >= 0xffffffff) {
-			fix = 1; 
-			break; 
-		} 
+		printk("CPU %d: aperture @ %Lx size %u MB\n", num-24, 
+		       aper_base, aper_size>>20);
 		
-		if (e820_mapped(aper_base, aper_base + aper_size, E820_RAM)) {  
-			printk("Aperture pointing to e820 RAM. Ignoring.\n");
+		char name[30];
+		sprintf(name, "northbridge cpu %d", num-24); 
+
+		if (!aperture_valid(name, aper_base, aper_size)) { 
 			fix = 1; 
 			break; 
 		} 
@@ -104,12 +218,40 @@
 	if (!fix && !fallback_aper_force) 
 		return; 
 
+	if (!fallback_aper_force)
+		aper_alloc = search_agp_bridge(&aper_order, &valid_agp); 
+		
+	if (aper_alloc) { 
+		/* Got the aperture from the AGP bridge */
+	} else if ((!no_iommu && end_pfn >= 0xffffffff>>PAGE_SHIFT) ||
+		   force_mmu ||
+		   valid_agp || 
+		   fallback_aper_force) { 
+		/* When there is a AGP bridge in the system assume the
+		   user wants to use the AGP driver too and needs an
+		   aperture.  However this case (AGP but no good
+		   aperture) should only happen with a more broken than
+		   usual BIOS, because it would even break Windows. */
+
 	printk("Your BIOS doesn't leave a aperture memory hole\n");
 	printk("Please enable the IOMMU option in the BIOS setup\n"); 
+		printk("This costs you %d MB of RAM\n", 32 << fallback_aper_order); 
+ 
+		aper_order = fallback_aper_order;
 	aper_alloc = allocate_aperture(); 
-	if (!aper_alloc) 
+		if (!aper_alloc) { 
+			/* Could disable AGP and IOMMU here, but it's probably
+			   not worth it. But the later users cannot deal with
+			   bad apertures and turning on the aperture over memory
+			   causes very strange problems, so it's better to 
+			   panic early. */
+			panic("Not enough memory for aperture");
+		}
+	} else { 
 		return; 
+	} 
 
+	/* Fix up the north bridges */
 	for (num = 24; num < 32; num++) { 		
 		if (read_pci_config(0, num, 3, 0x00) != NB_ID_3) 
 			continue;	
@@ -117,7 +259,7 @@
 		/* Don't enable translation yet. That is done later. 
 		   Assume this BIOS didn't initialise the GART so 
 		   just overwrite all previous bits */ 
-		write_pci_config(0, num, 3, 0x90, fallback_aper_order<<1); 
+		write_pci_config(0, num, 3, 0x90, aper_order<<1); 
 		write_pci_config(0, num, 3, 0x94, aper_alloc>>25); 
 	} 
 }