of/irq: Add of_irq_parse_and_map_pci() and related function

The patch addes of_irq_parse_and_map_pci() and related function
which will be used by Layerscape PCIe driver.

of_irq_parse_raw() and of_irq_parse_one() are copied from
Linux 3.17 drivers/of/irq.c.
The related commit ID include:
7dc2e1134a22dc242175d5321c0c9e97d16eb87b
2361613206e66ce59cc0e08efa8d98ec15b84ed1
624cfca534f9b1ffb1326617b4e973a3d5ecff4a
a9ecdc0fdc54aa499604dbd43132988effcac9b4
355e62f5ad12b005c862838156262eb2df2f8dff
a7c194b007ec40a130207e9ace9cecf598fc6ac5
0c02c8007ea5554d028f99fd3e29fc201fdeeab3
530210c7814e83564c7ca7bca8192515042c0b63

of_irq_parse_pci() and of_irq_parse_and_map_pci() are copied
from Linux 3.17 drivers/of/of_pci_irq.c
The related commit ID include:
98d9f30c820d509145757e6ecbc36013aa02f7bc
2361613206e66ce59cc0e08efa8d98ec15b84ed1
16b84e5a505c790538e534ad8dfda9c288691e40
0c02c8007ea5554d028f99fd3e29fc201fdeeab3
530210c7814e83564c7ca7bca8192515042c0b63

irq_create_of_mapping_new() is copied from Linux 3.17
kernel/irq/irqdomain.c irq_create_of_mapping().
The related commit ID include:
e6d30ab1e7d1281784672c0fc2ffa385cfb7279e

The copyright is owned by the author of the related commit ID
You can find out the detailed copyright information based on
the commit ID in the upstream repository.

Signed-off-by: Minghuan Lian <Minghuan.Lian@freescale.com>
Change-Id: I24bcaaea4c6cbe43229bccaceb80e74f57a9ef93
Reviewed-on: http://git.am.freescale.net:8181/19677
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Yang Li <LeoLi@freescale.com>
Reviewed-by: Zhengxiong Jin <Jason.Jin@freescale.com>

1 files changed, 113 insertions, 0 deletions

diff --git a/drivers/of/of_pci_irq.c b/drivers/of/of_pci_irq.c
index 6770538..3843b46 100644
--- a/drivers/of/of_pci_irq.c
+++ b/drivers/of/of_pci_irq.c
@@ -91,3 +91,116 @@ int of_irq_map_pci(const struct pci_dev *pdev, struct of_irq *out_irq)
 	return of_irq_map_raw(ppnode, &lspec_be, 1, laddr, out_irq);
 }
 EXPORT_SYMBOL_GPL(of_irq_map_pci);
+
+/**
+ * of_irq_parse_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_parse_pci(const struct pci_dev *pdev,
+		     struct of_phandle_args *out_irq)
+{
+	struct device_node *dn, *ppnode;
+	struct pci_dev *ppdev;
+	__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_parse_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 */
+	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
+		 */
+		pin = pci_swizzle_interrupt_pin(pdev, pin);
+		pdev = ppdev;
+	}
+
+	out_irq->np = ppnode;
+	out_irq->args_count = 1;
+	out_irq->args[0] = pin;
+	laddr[0] = cpu_to_be32((pdev->bus->number << 16) | (pdev->devfn << 8));
+	laddr[1] = laddr[2] = cpu_to_be32(0);
+	return of_irq_parse_raw(laddr, out_irq);
+}
+EXPORT_SYMBOL_GPL(of_irq_parse_pci);
+
+/**
+ * of_irq_parse_and_map_pci() - Decode a PCI irq from the device tree and map to a virq
+ * @dev: The pci device needing an irq
+ * @slot: PCI slot number; passed when used as map_irq callback. Unused
+ * @pin: PCI irq pin number; passed when used as map_irq callback. Unused
+ *
+ * @slot and @pin are unused, but included in the function so that this
+ * function can be used directly as the map_irq callback to pci_fixup_irqs().
+ */
+int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+	struct of_phandle_args oirq;
+	int ret;
+
+	ret = of_irq_parse_pci(dev, &oirq);
+	if (ret) {
+		dev_err(&dev->dev,
+			"of_irq_parse_pci() failed with rc=%d\n", ret);
+		return 0; /* Proper return code 0 == NO_IRQ */
+	}
+
+	return irq_create_of_mapping_new(&oirq);
+}
+EXPORT_SYMBOL_GPL(of_irq_parse_and_map_pci);