[ACPI] acpi_pci_irq_enable() now returns 0 on success.

This bubbles all the way up to pci_enable_device().
This allows IRQ0 to be used as a legal PCI device IRQ.

The ES7000 uses an interrupt source override to assign pin20 to IRQ0.
Then platform_rename_gsi assigns pin0 a high-numbered IRQ -- available
for PCI devices.  But IRQ0 needs to be a legal PCI IRQ in the lookup code
to make it as far as the re-name code. 
Signed-off-by: Natalie Protasevich <Natalie.Protasevich@UNISYS.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/pci_irq.c

@@ -227,6 +227,11 @@ acpi_pci_irq_add_prt (
                           PCI Interrupt Routing Support
    -------------------------------------------------------------------------- */
 
+/*
+ * acpi_pci_irq_lookup
+ * success: return IRQ >= 0
+ * failure: return -1
+ */
 static int
 acpi_pci_irq_lookup (
 	struct pci_bus		*bus,
@@ -249,14 +254,14 @@ acpi_pci_irq_lookup (
 	entry = acpi_pci_irq_find_prt_entry(segment, bus_nr, device, pin); 
 	if (!entry) {
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "PRT entry not found\n"));
-		return_VALUE(0);
+		return_VALUE(-1);
 	}
 	
 	if (entry->link.handle) {
 		irq = acpi_pci_link_get_irq(entry->link.handle, entry->link.index, edge_level, active_high_low);
-		if (!irq) {
+		if (irq < 0) {
 			ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Invalid IRQ link routing entry\n"));
-			return_VALUE(0);
+			return_VALUE(-1);
 		}
 	} else {
 		irq = entry->link.index;
@@ -269,6 +274,11 @@ acpi_pci_irq_lookup (
 	return_VALUE(irq);
 }
 
+/*
+ * acpi_pci_irq_derive
+ * success: return IRQ >= 0
+ * failure: return < 0
+ */
 static int
 acpi_pci_irq_derive (
 	struct pci_dev		*dev,
@@ -277,7 +287,7 @@ acpi_pci_irq_derive (
 	int			*active_high_low)
 {
 	struct pci_dev		*bridge = dev;
-	int			irq = 0;
+	int			irq = -1;
 	u8			bridge_pin = 0;
 
 	ACPI_FUNCTION_TRACE("acpi_pci_irq_derive");
@@ -289,7 +299,7 @@ acpi_pci_irq_derive (
 	 * Attempt to derive an IRQ for this device from a parent bridge's
 	 * PCI interrupt routing entry (eg. yenta bridge and add-in card bridge).
 	 */
-	while (!irq && bridge->bus->self) {
+	while (irq < 0 && bridge->bus->self) {
 		pin = (pin + PCI_SLOT(bridge->devfn)) % 4;
 		bridge = bridge->bus->self;
 
@@ -299,7 +309,7 @@ acpi_pci_irq_derive (
 			if (!bridge_pin) {
 				ACPI_DEBUG_PRINT((ACPI_DB_INFO, 
 					"No interrupt pin configured for device %s\n", pci_name(bridge)));
-				return_VALUE(0);
+				return_VALUE(-1);
 			}
 			/* Pin is from 0 to 3 */
 			bridge_pin --;
@@ -310,9 +320,9 @@ acpi_pci_irq_derive (
 			pin, edge_level, active_high_low);
 	}
 
-	if (!irq) {
+	if (irq < 0) {
 		ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Unable to derive IRQ for device %s\n", pci_name(dev)));
-		return_VALUE(0);
+		return_VALUE(-1);
 	}
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Derive IRQ %d for device %s from %s\n",
@@ -321,6 +331,11 @@ acpi_pci_irq_derive (
 	return_VALUE(irq);
 }
 
+/*
+ * acpi_pci_irq_enable
+ * success: return 0
+ * failure: return < 0
+ */
 
 int
 acpi_pci_irq_enable (
@@ -358,20 +373,20 @@ acpi_pci_irq_enable (
 	 * If no PRT entry was found, we'll try to derive an IRQ from the
 	 * device's parent bridge.
 	 */
-	if (!irq)
+	if (irq < 0)
  		irq = acpi_pci_irq_derive(dev, pin, &edge_level, &active_high_low);
  
 	/*
 	 * No IRQ known to the ACPI subsystem - maybe the BIOS / 
 	 * driver reported one, then use it. Exit in any case.
 	 */
-	if (!irq) {
+	if (irq < 0) {
 		printk(KERN_WARNING PREFIX "PCI interrupt %s[%c]: no GSI",
 			pci_name(dev), ('A' + pin));
 		/* Interrupt Line values above 0xF are forbidden */
-		if (dev->irq && (dev->irq <= 0xF)) {
+		if (dev->irq >= 0 && (dev->irq <= 0xF)) {
 			printk(" - using IRQ %d\n", dev->irq);
-			return_VALUE(dev->irq);
+			return_VALUE(0);
 		}
 		else {
 			printk("\n");
@@ -388,5 +403,5 @@ acpi_pci_irq_enable (
 		(active_high_low == ACPI_ACTIVE_LOW) ? "low" : "high",
 		dev->irq);
 
-	return_VALUE(dev->irq);
+	return_VALUE(0);
 }

drivers/acpi/pci_link.c

@@ -577,6 +577,11 @@ static int acpi_pci_link_allocate(struct acpi_pci_link* link) {
 	return_VALUE(0);
 }
 
+/*
+ * acpi_pci_link_get_irq
+ * success: return IRQ >= 0
+ * failure: return -1
+ */
 
 int
 acpi_pci_link_get_irq (
@@ -594,27 +599,27 @@ acpi_pci_link_get_irq (
 	result = acpi_bus_get_device(handle, &device);
 	if (result) {
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid link device\n"));
-		return_VALUE(0);
+		return_VALUE(-1);
 	}
 
 	link = (struct acpi_pci_link *) acpi_driver_data(device);
 	if (!link) {
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid link context\n"));
-		return_VALUE(0);
+		return_VALUE(-1);
 	}
 
 	/* TBD: Support multiple index (IRQ) entries per Link Device */
 	if (index) {
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Invalid index %d\n", index));
-		return_VALUE(0);
+		return_VALUE(-1);
 	}
 
 	if (acpi_pci_link_allocate(link))
-		return_VALUE(0);
+		return_VALUE(-1);
 	   
 	if (!link->irq.active) {
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Link active IRQ is 0!\n"));
-		return_VALUE(0);
+		return_VALUE(-1);
 	}
 
 	if (edge_level) *edge_level = link->irq.edge_level;