of/pci: move of_irq_map_pci() into generic code

There is a tiny difference between PPC32 and PPC64. Microblaze uses the
PPC32 variant.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
[grant.likely@secretlab.ca: Added comment to #endif, moved documentation
	block to function implementation, fixed for non ppc and microblaze
	compiles]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 91 insertions, 0 deletions

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
new file mode 100644
index 000000000000..314535fa32c1
--- /dev/null
+++ b/drivers/of/of_pci.c
@@ -0,0 +1,91 @@
+#include <linux/kernel.h>
+#include <linux/of_pci.h>
+#include <asm/prom.h>
+
+/**
+ * of_irq_map_pci - Resolve the interrupt for a PCI device
+ * @pdev:       the device whose interrupt is to be resolved
+ * @out_irq:    structure of_irq filled by this function
+ *
+ * This function resolves the PCI interrupt for a given PCI device. If a
+ * device-node exists for a given pci_dev, it will use normal OF tree
+ * walking. If not, it will implement standard swizzling and walk up the
+ * PCI tree until an device-node is found, at which point it will finish
+ * resolving using the OF tree walking.
+ */
+int of_irq_map_pci(struct pci_dev *pdev, struct of_irq *out_irq)
+{
+        struct device_node *dn, *ppnode;
+        struct pci_dev *ppdev;
+        u32 lspec;
+        __be32 lspec_be;
+        __be32 laddr[3];
+        u8 pin;
+        int rc;
+
+        /* Check if we have a device node, if yes, fallback to standard
+         * device tree parsing
+         */
+        dn = pci_device_to_OF_node(pdev);
+        if (dn) {
+                rc = of_irq_map_one(dn, 0, out_irq);
+                if (!rc)
+                        return rc;
+        }
+
+        /* Ok, we don't, time to have fun. Let's start by building up an
+         * interrupt spec.  we assume #interrupt-cells is 1, which is standard
+         * for PCI. If you do different, then don't use that routine.
+         */
+        rc = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
+        if (rc != 0)
+                return rc;
+        /* No pin, exit */
+        if (pin == 0)
+                return -ENODEV;
+
+        /* Now we walk up the PCI tree */
+        lspec = pin;
+        for (;;) {
+                /* Get the pci_dev of our parent */
+                ppdev = pdev->bus->self;
+
+                /* Ouch, it's a host bridge... */
+                if (ppdev == NULL) {
+                        ppnode = pci_bus_to_OF_node(pdev->bus);
+
+                        /* No node for host bridge ? give up */
+                        if (ppnode == NULL)
+                                return -EINVAL;
+                } else {
+                        /* We found a P2P bridge, check if it has a node */
+                        ppnode = pci_device_to_OF_node(ppdev);
+                }
+
+                /* Ok, we have found a parent with a device-node, hand over to
+                 * the OF parsing code.
+                 * We build a unit address from the linux device to be used for
+                 * resolution. Note that we use the linux bus number which may
+                 * not match your firmware bus numbering.
+                 * Fortunately, in most cases, interrupt-map-mask doesn't
+                 * include the bus number as part of the matching.
+                 * You should still be careful about that though if you intend
+                 * to rely on this function (you ship  a firmware that doesn't
+                 * create device nodes for all PCI devices).
+                 */
+                if (ppnode)
+                        break;
+
+                /* We can only get here if we hit a P2P bridge with no node,
+                 * let's do standard swizzling and try again
+                 */
+                lspec = pci_swizzle_interrupt_pin(pdev, lspec);
+                pdev = ppdev;
+        }
+
+        lspec_be = cpu_to_be32(lspec);
+        laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
+        laddr[1]  = laddr[2] = cpu_to_be32(0);
+        return of_irq_map_raw(ppnode, &lspec_be, 1, laddr, out_irq);
+}
+EXPORT_SYMBOL_GPL(of_irq_map_pci);