x86, irq: Reorganize IO_APIC_get_PCI_irq_vector() to prepare for irqdomain

Reorganize function IO_APIC_get_PCI_irq_vector() a bit to better support
coming irqdomain.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1402302011-23642-16-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/io_apic.c

@@ -997,7 +997,7 @@ static int pin_2_irq(int idx, int apic, int pin)
 int IO_APIC_get_PCI_irq_vector(int bus, int slot, int pin,
 				struct io_apic_irq_attr *irq_attr)
 {
-	int ioapic_idx, i, best_guess = -1;
+	int irq, i, best_guess = -1;
 
 	apic_printk(APIC_DEBUG,
 		    "querying PCI -> IRQ mapping bus:%d, slot:%d, pin:%d.\n",
@@ -1007,41 +1007,46 @@ int IO_APIC_get_PCI_irq_vector(int bus, int slot, int pin,
 			    "PCI BIOS passed nonexistent PCI bus %d!\n", bus);
 		return -1;
 	}
+
 	for (i = 0; i < mp_irq_entries; i++) {
 		int lbus = mp_irqs[i].srcbus;
+		int ioapic_idx, found = 0;
+
+		if (bus != lbus || mp_irqs[i].irqtype != mp_INT ||
+		    slot != ((mp_irqs[i].srcbusirq >> 2) & 0x1f))
+			continue;
 
 		for_each_ioapic(ioapic_idx)
 			if (mpc_ioapic_id(ioapic_idx) == mp_irqs[i].dstapic ||
-			    mp_irqs[i].dstapic == MP_APIC_ALL)
+			    mp_irqs[i].dstapic == MP_APIC_ALL) {
+				found = 1;
 				break;
+			}
+		if (!found)
+			continue;
 
-		if (!test_bit(lbus, mp_bus_not_pci) &&
-		    mp_irqs[i].irqtype == mp_INT &&
-		    (bus == lbus) &&
-		    (slot == ((mp_irqs[i].srcbusirq >> 2) & 0x1f))) {
-			int irq = pin_2_irq(i, ioapic_idx, mp_irqs[i].dstirq);
-
-			if (!(ioapic_idx || IO_APIC_IRQ(irq)))
-				continue;
+		/* Skip ISA IRQs */
+		irq = pin_2_irq(i, ioapic_idx, mp_irqs[i].dstirq);
+		if (ioapic_idx == 0 && !IO_APIC_IRQ(irq))
+			continue;
 
-			if (pin == (mp_irqs[i].srcbusirq & 3)) {
-				set_io_apic_irq_attr(irq_attr, ioapic_idx,
-						     mp_irqs[i].dstirq,
-						     irq_trigger(i),
-						     irq_polarity(i));
-				return irq;
-			}
-			/*
-			 * Use the first all-but-pin matching entry as a
-			 * best-guess fuzzy result for broken mptables.
-			 */
-			if (best_guess < 0) {
-				set_io_apic_irq_attr(irq_attr, ioapic_idx,
-						     mp_irqs[i].dstirq,
-						     irq_trigger(i),
-						     irq_polarity(i));
-				best_guess = irq;
-			}
+		if (pin == (mp_irqs[i].srcbusirq & 3)) {
+			set_io_apic_irq_attr(irq_attr, ioapic_idx,
+					     mp_irqs[i].dstirq,
+					     irq_trigger(i),
+					     irq_polarity(i));
+			return irq;
+		}
+		/*
+		 * Use the first all-but-pin matching entry as a
+		 * best-guess fuzzy result for broken mptables.
+		 */
+		if (best_guess < 0) {
+			set_io_apic_irq_attr(irq_attr, ioapic_idx,
+					     mp_irqs[i].dstirq,
+					     irq_trigger(i),
+					     irq_polarity(i));
+			best_guess = irq;
 		}
 	}
 	return best_guess;