ia64: Forward-port hp-agp.c fix from 2.4

See this ChangeSet:

http://lia64.bkbits.net:8080/linux-ia64-2.4/cset@40524248tkgE0RDYQL0IyiAdFxo_Ew

drivers/char/agp/hp-agp.c

@@ -27,10 +27,6 @@
 #define HP_ZX1_TCNFG		0x318
 #define HP_ZX1_PDIR_BASE	0x320
 
-/* HP ZX1 LBA registers */
-#define HP_ZX1_AGP_STATUS	0x64
-#define HP_ZX1_AGP_COMMAND	0x68
-
 #define HP_ZX1_IOVA_BASE	GB(1UL)
 #define HP_ZX1_IOVA_SIZE	GB(1UL)
 #define HP_ZX1_GART_SIZE	(HP_ZX1_IOVA_SIZE / 2)
@@ -39,6 +35,9 @@
 #define HP_ZX1_PDIR_VALID_BIT	0x8000000000000000UL
 #define HP_ZX1_IOVA_TO_PDIR(va)	((va - hp_private.iova_base) >> hp_private.io_tlb_shift)
 
+#define AGP8X_MODE_BIT		3
+#define AGP8X_MODE		(1 << AGP8X_MODE_BIT)
+
 /* AGP bridge need not be PCI device, but DRM thinks it is. */
 static struct pci_dev fake_bridge_dev;
 
@@ -57,6 +56,7 @@ static struct gatt_mask hp_zx1_masks[] =
 static struct _hp_private {
 	volatile u8 *ioc_regs;
 	volatile u8 *lba_regs;
+	int lba_cap_offset;
 	u64 *io_pdir;		// PDIR for entire IOVA
 	u64 *gatt;		// PDIR just for GART (subset of above)
 	u64 gatt_entries;
@@ -109,6 +109,7 @@ static int __init hp_zx1_ioc_shared(void)
 	hp->gatt = &hp->io_pdir[HP_ZX1_IOVA_TO_PDIR(hp->gart_base)];
 
 	if (hp->gatt[0] != HP_ZX1_SBA_IOMMU_COOKIE) {
+		/* Normal case when no AGP device in system */
 	    	hp->gatt = 0;
 		hp->gatt_entries = 0;
 		printk(KERN_ERR PFX "No reserved IO PDIR entry found; "
@@ -156,12 +157,13 @@ hp_zx1_ioc_owner (void)
 }
 
 static int __init
-hp_zx1_ioc_init (u64 ioc_hpa, u64 lba_hpa)
+hp_zx1_ioc_init (u64 hpa)
 {
 	struct _hp_private *hp = &hp_private;
 
-	hp->ioc_regs = ioremap(ioc_hpa, 1024);
-	hp->lba_regs = ioremap(lba_hpa, 256);
+	hp->ioc_regs = ioremap(hpa, 1024);
+	if (!hp->ioc_regs)
+		return -ENOMEM;
 
 	/*
 	 * If the IOTLB is currently disabled, we can take it over.
@@ -175,6 +177,51 @@ hp_zx1_ioc_init (u64 ioc_hpa, u64 lba_hpa)
 	return hp_zx1_ioc_shared();
 }
 
+static int
+hp_zx1_lba_find_capability (volatile u8 *hpa, int cap)
+{
+	u16 status;
+	u8 pos, id;
+	int ttl = 48;
+
+	status = INREG16(hpa, PCI_STATUS);
+	if (!(status & PCI_STATUS_CAP_LIST))
+		return 0;
+	pos = INREG8(hpa, PCI_CAPABILITY_LIST);
+	while (ttl-- && pos >= 0x40) {
+		pos &= ~3;
+		id = INREG8(hpa, pos + PCI_CAP_LIST_ID);
+		if (id == 0xff)
+			break;
+		if (id == cap)
+			return pos;
+		pos = INREG8(hpa, pos + PCI_CAP_LIST_NEXT);
+	}
+	return 0;
+}
+
+static int __init
+hp_zx1_lba_init (u64 hpa)
+{
+	struct _hp_private *hp = &hp_private;
+	int cap;
+
+	hp->lba_regs = ioremap(hpa, 256);
+	if (!hp->lba_regs)
+		return -ENOMEM;
+
+	hp->lba_cap_offset = hp_zx1_lba_find_capability(hp->lba_regs, PCI_CAP_ID_AGP);
+
+	cap = INREG32(hp->lba_regs, hp->lba_cap_offset) & 0xff;
+	if (cap != PCI_CAP_ID_AGP) {
+		printk(KERN_ERR PFX "Invalid capability ID 0x%02x at 0x%x\n",
+		       cap, hp->lba_cap_offset);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static int
 hp_zx1_fetch_size(void)
 {
@@ -192,13 +239,8 @@ hp_zx1_configure (void)
 	struct _hp_private *hp = &hp_private;
 
 	agp_bridge->gart_bus_addr = hp->gart_base;
-#if 0
-	/* ouch!! can't do that with a non-PCI AGP bridge... */
-	agp_bridge->capndx = pci_find_capability(agp_bridge->dev, PCI_CAP_ID_AGP);
-#else
-	agp_bridge->capndx = 0;
-#endif
-	agp_bridge->mode = INREG32(hp->lba_regs, HP_ZX1_AGP_STATUS);
+	agp_bridge->capndx = hp->lba_cap_offset;
+	agp_bridge->mode = INREG32(hp->lba_regs, hp->lba_cap_offset + PCI_AGP_STATUS);
 
 	if (hp->io_pdir_owner) {
 		OUTREG64(hp->ioc_regs, HP_ZX1_PDIR_BASE, virt_to_phys(hp->io_pdir));
@@ -217,9 +259,13 @@ hp_zx1_cleanup (void)
 {
 	struct _hp_private *hp = &hp_private;
 
-	if (hp->io_pdir_owner)
-		OUTREG64(hp->ioc_regs, HP_ZX1_IBASE, 0);
-	iounmap((void *) hp->ioc_regs);
+	if (hp->ioc_regs) {
+		if (hp->io_pdir_owner)
+			OUTREG64(hp->ioc_regs, HP_ZX1_IBASE, 0);
+		iounmap((void *) hp->ioc_regs);
+	}
+	if (hp->lba_regs)
+		iounmap((void *) hp->lba_regs);
 }
 
 static void
@@ -350,14 +396,14 @@ hp_zx1_enable (u32 mode)
 	struct _hp_private *hp = &hp_private;
 	u32 command;
 
-	command = INREG32(hp->lba_regs, HP_ZX1_AGP_STATUS);
+	command = INREG32(hp->lba_regs, hp->lba_cap_offset + PCI_AGP_STATUS);
 
 	command = agp_collect_device_status(mode, command);
 	command |= 0x00000100;
 
-	OUTREG32(hp->lba_regs, HP_ZX1_AGP_COMMAND, command);
+	OUTREG32(hp->lba_regs, hp->lba_cap_offset + PCI_AGP_COMMAND, command);
 
-	agp_device_command(command, 0);
+	agp_device_command(command, (mode & AGP8X_MODE) != 0);
 }
 
 struct agp_bridge_driver hp_zx1_driver = {
@@ -386,22 +432,32 @@ static int __init
 hp_zx1_setup (u64 ioc_hpa, u64 lba_hpa)
 {
 	struct agp_bridge_data *bridge;
-	int error;
+	int error = 0;
+
+	error = hp_zx1_ioc_init(ioc_hpa);
+	if (error)
+		goto fail;
 
-	error = hp_zx1_ioc_init(ioc_hpa, lba_hpa);
+	error = hp_zx1_lba_init(lba_hpa);
 	if (error)
-		return error;
+		goto fail;
 
 	bridge = agp_alloc_bridge();
-	if (!bridge)
-		return -ENOMEM;
+	if (!bridge) {
+		error = -ENOMEM;
+		goto fail;
+	}
 	bridge->driver = &hp_zx1_driver;
 
 	fake_bridge_dev.vendor = PCI_VENDOR_ID_HP;
 	fake_bridge_dev.device = PCI_DEVICE_ID_HP_PCIX_LBA;
 	bridge->dev = &fake_bridge_dev;
 
-	return agp_add_bridge(bridge);
+	error = agp_add_bridge(bridge);
+  fail:
+	if (error)
+		hp_zx1_cleanup();
+	return error;
 }
 
 static acpi_status __init
@@ -416,7 +472,7 @@ zx1_gart_probe (acpi_handle obj, u32 depth, void *context, void **ret)
 
 	status = hp_acpi_csr_space(obj, &lba_hpa, &length);
 	if (ACPI_FAILURE(status))
-		return AE_OK;
+		return AE_OK; /* keep looking for another bridge */
 
 	/* Look for an enclosing IOC scope and find its CSR space */
 	handle = obj;
@@ -452,7 +508,7 @@ zx1_gart_probe (acpi_handle obj, u32 depth, void *context, void **ret)
 		(char *) context, sba_hpa + HP_ZX1_IOC_OFFSET, lba_hpa);
 
 	hp_zx1_gart_found = 1;
-	return AE_CTRL_TERMINATE;
+	return AE_CTRL_TERMINATE; /* we only support one bridge; quit looking */
 }
 
 static int __init