[PATCH 02/12] MIPS: Netlogic: MSI enable fix for XLS

["Jayachandran C" <jayachandranc@netlogicmicro.com>]

From: Ganesan Ramalingam <ganesanr@broadcom.com>

MSI interrupts do not work on XLS after commit a776c49, because
the change disables MSI interrupts on the XLS PCIe bridges at boot-up.

Fix this by enabling MSI interrupts on the bridge in the
arch_setup_msi_irq() function. Earlier, this was done from firmware
and we did not need to change the configuration in linux.

Signed-off-by: Ganesan Ramalingam <ganesanr@broadcom.com>
Signed-off-by: Jayachandran C <jayachandranc@netlogicmicro.com>
---
 arch/mips/pci/pci-xlr.c |   30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/mips/pci/pci-xlr.c b/arch/mips/pci/pci-xlr.c
index 50ff4dc..003e053 100644
--- a/arch/mips/pci/pci-xlr.c
+++ b/arch/mips/pci/pci-xlr.c
@@ -41,6 +41,7 @@
 #include <linux/irq.h>
 #include <linux/irqdesc.h>
 #include <linux/console.h>
+#include <linux/pci_regs.h>
 
 #include <asm/io.h>
 
@@ -168,17 +169,17 @@ static int get_irq_vector(const struct pci_dev *dev)
        if (dev->bus->self == NULL)
                return 0;
 
-       switch  (dev->bus->self->devfn) {
-       case 0x0:
+       switch  (PCI_SLOT(dev->bus->self->devfn)) {
+       case 0:
                return PIC_PCIE_LINK0_IRQ;
-       case 0x8:
+       case 1:
                return PIC_PCIE_LINK1_IRQ;
-       case 0x10:
+       case 2:
                if (nlm_chip_is_xls_b())
                        return PIC_PCIE_XLSB0_LINK2_IRQ;
                else
                        return PIC_PCIE_LINK2_IRQ;
-       case 0x18:
+       case 3:
                if (nlm_chip_is_xls_b())
                        return PIC_PCIE_XLSB0_LINK3_IRQ;
                else
@@ -202,7 +203,26 @@ void arch_teardown_msi_irq(unsigned int irq)
 int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 {
        struct msi_msg msg;
+       struct pci_bus *bus, *p;
        int irq, ret;
+       u16 val;
+
+       /* Find the bridge on bus 0 */
+       bus = dev->bus;
+       for (p = bus->parent; p && p->number != 0; p = p->parent)
+               bus = p;
+       if (p == NULL)
+               return 1;
+
+       /*
+        * Enable MSI which was disabled at enumeration, the bridge
+        * MSI capability is at 0x50
+        */
+       pci_read_config_word(bus->self, 0x50 + PCI_MSI_FLAGS, &val);
+       if ((val & PCI_MSI_FLAGS_ENABLE) == 0) {
+               val |= PCI_MSI_FLAGS_ENABLE;
+               pci_write_config_word(bus->self, 0x50 + PCI_MSI_FLAGS, val);
+       }
 
        irq = get_irq_vector(dev);
        if (irq <= 0)
-- 
1.7.9.5