PCI: mvebu: add support for MSI

This commit adds support for Message Signaled Interrupts in the
Marvell PCIe host controller. The work is very simple: it simply gets
a reference to the msi_chip associated to the PCIe controller thanks
to the msi-parent DT property, and stores this reference in the
pci_bus structure. This is enough to let the Linux PCI core use the
functions of msi_chip to setup and teardown MSIs.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

Documentation/devicetree/bindings/pci/mvebu-pci.txt

@@ -14,6 +14,8 @@ Mandatory properties:
 - ranges: ranges describing the MMIO registers to control the PCIe
   interfaces, and ranges describing the MBus windows needed to access
   the memory and I/O regions of each PCIe interface.
+- msi-parent: Link to the hardware entity that serves as the Message
+  Signaled Interrupt controller for this PCI controller.
 
 The ranges describing the MMIO registers have the following layout:
 
@@ -86,6 +88,7 @@ pcie-controller {
 	#size-cells = <2>;
 
 	bus-range = <0x00 0xff>;
+	msi-parent = <&mpic>;
 
 	ranges =
 	       <0x82000000 0 0x40000 MBUS_ID(0xf0, 0x01) 0x40000 0 0x00002000	/* Port 0.0 registers */

drivers/pci/host/pci-mvebu.c

@@ -11,6 +11,7 @@
 #include <linux/clk.h>
 #include <linux/module.h>
 #include <linux/mbus.h>
+#include <linux/msi.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/of_address.h>
@@ -103,6 +104,7 @@ struct mvebu_pcie_port;
 struct mvebu_pcie {
 	struct platform_device *pdev;
 	struct mvebu_pcie_port *ports;
+	struct msi_chip *msi;
 	struct resource io;
 	struct resource realio;
 	struct resource mem;
@@ -673,6 +675,12 @@ static struct pci_bus *mvebu_pcie_scan_bus(int nr, struct pci_sys_data *sys)
 	return bus;
 }
 
+void mvebu_pcie_add_bus(struct pci_bus *bus)
+{
+	struct mvebu_pcie *pcie = sys_to_pcie(bus->sysdata);
+	bus->msi = pcie->msi;
+}
+
 resource_size_t mvebu_pcie_align_resource(struct pci_dev *dev,
 					  const struct resource *res,
 					  resource_size_t start,
@@ -709,6 +717,7 @@ static void __init mvebu_pcie_enable(struct mvebu_pcie *pcie)
 	hw.map_irq        = mvebu_pcie_map_irq;
 	hw.ops            = &mvebu_pcie_ops;
 	hw.align_resource = mvebu_pcie_align_resource;
+	hw.add_bus        = mvebu_pcie_add_bus;
 
 	pci_common_init(&hw);
 }
@@ -777,6 +786,21 @@ static int mvebu_get_tgt_attr(struct device_node *np, int devfn,
 	return -ENOENT;
 }
 
+static void __init mvebu_pcie_msi_enable(struct mvebu_pcie *pcie)
+{
+	struct device_node *msi_node;
+
+	msi_node = of_parse_phandle(pcie->pdev->dev.of_node,
+				    "msi-parent", 0);
+	if (!msi_node)
+		return;
+
+	pcie->msi = of_pci_find_msi_chip_by_node(msi_node);
+
+	if (pcie->msi)
+		pcie->msi->dev = &pcie->pdev->dev;
+}
+
 static int __init mvebu_pcie_probe(struct platform_device *pdev)
 {
 	struct mvebu_pcie *pcie;
@@ -912,6 +936,8 @@ static int __init mvebu_pcie_probe(struct platform_device *pdev)
 		i++;
 	}
 
+	mvebu_pcie_msi_enable(pcie);
+
 	mvebu_pcie_enable(pcie);
 
 	return 0;