m68k/PCI: Replace pci_fixup_irqs() call with host bridge IRQ mapping hooks

The pci_fixup_irqs() function allocates IRQs for all PCI devices present in
a system; those PCI devices possibly belong to different PCI bus trees (and
possibly rooted at different host bridges) and may well be enabled (ie
probed and bound to a driver) by the time pci_fixup_irqs() is called when
probing a given host bridge driver.

Furthermore, current kernel code relying on pci_fixup_irqs() to assign
legacy PCI IRQs to devices does not work at all for hotplugged devices in
that the code carrying out the IRQ fixup is called at host bridge driver
probe time, which just cannot take into account devices hotplugged after
the system has booted.

The introduction of map/swizzle function hooks in struct pci_host_bridge
allows us to define per-bridge map/swizzle functions that can be used at
device probe time in PCI core code to allocate IRQs for a given device
(through pci_assign_irq()).

Convert PCI host bridge initialization code to the
pci_scan_root_bus_bridge() API (that allows to pass a struct
pci_host_bridge with initialized map/swizzle pointers) and remove the
pci_fixup_irqs() call from arch code.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/coldfire/pci.c

@@ -243,6 +243,13 @@ static struct resource mcf_pci_io = {
 	.flags	= IORESOURCE_IO,
 };
 
+static struct resource busn_resource = {
+	.name	= "PCI busn",
+	.start	= 0,
+	.end	= 255,
+	.flags	= IORESOURCE_BUS,
+};
+
 /*
  * Interrupt mapping and setting.
  */
@@ -258,6 +265,13 @@ static int mcf_pci_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
 
 static int __init mcf_pci_init(void)
 {
+	struct pci_host_bridge *bridge;
+	int ret;
+
+	bridge = pci_alloc_host_bridge(0);
+	if (!bridge)
+		return -ENOMEM;
+
 	pr_info("ColdFire: PCI bus initialization...\n");
 
 	/* Reset the external PCI bus */
@@ -312,14 +326,28 @@ static int __init mcf_pci_init(void)
 	set_current_state(TASK_UNINTERRUPTIBLE);
 	schedule_timeout(msecs_to_jiffies(200));
 
-	rootbus = pci_scan_bus(0, &mcf_pci_ops, NULL);
-	if (!rootbus)
-		return -ENODEV;
+
+	pci_add_resource(&bridge->windows, &ioport_resource);
+	pci_add_resource(&bridge->windows, &iomem_resource);
+	pci_add_resource(&bridge->windows, &busn_resource);
+	bridge->dev.parent = NULL;
+	bridge->sysdata = NULL;
+	bridge->busnr = 0;
+	bridge->ops = &mcf_pci_ops;
+	bridge->swizzle_irq = pci_common_swizzle;
+	bridge->map_irq = mcf_pci_map_irq;
+
+	ret = pci_scan_root_bus_bridge(bridge);
+	if (ret) {
+		pci_free_host_bridge(bridge);
+		return ret;
+	}
+
+	rootbus = bridge->bus;
 
 	rootbus->resource[0] = &mcf_pci_io;
 	rootbus->resource[1] = &mcf_pci_mem;
 
-	pci_fixup_irqs(pci_common_swizzle, mcf_pci_map_irq);
 	pci_bus_size_bridges(rootbus);
 	pci_bus_assign_resources(rootbus);
 	pci_bus_add_devices(rootbus);