1 files changed, 37 insertions, 3 deletions

diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index d34f4ffdb796..6d2f0abce6fa 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -374,6 +374,23 @@ static int check_msix_entries(struct pci_dev *pdev)
         return 0;
 }
 
+static void rtas_hack_32bit_msi_gen2(struct pci_dev *pdev)
+{
+        u32 addr_hi, addr_lo;
+
+        /*
+         * We should only get in here for IODA1 configs. This is based on the
+         * fact that we using RTAS for MSIs, we don't have the 32 bit MSI RTAS
+         * support, and we are in a PCIe Gen2 slot.
+         */
+        dev_info(&pdev->dev,
+                 "rtas_msi: No 32 bit MSI firmware support, forcing 32 bit MSI\n");
+        pci_read_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, &addr_hi);
+        addr_lo = 0xffff0000 | ((addr_hi >> (48 - 32)) << 4);
+        pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO, addr_lo);
+        pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, 0);
+}
+
 static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
 {
         struct pci_dn *pdn;
@@ -381,6 +398,7 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
         struct msi_desc *entry;
         struct msi_msg msg;
         int nvec = nvec_in;
+        int use_32bit_msi_hack = 0;
 
         pdn = pci_get_pdn(pdev);
         if (!pdn)
@@ -408,15 +426,31 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
          */
 again:
         if (type == PCI_CAP_ID_MSI) {
-                if (pdn->force_32bit_msi)
+                if (pdn->force_32bit_msi) {
                         rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
-                else
+                        if (rc < 0) {
+                                /*
+                                 * We only want to run the 32 bit MSI hack below if
+                                 * the max bus speed is Gen2 speed
+                                 */
+                                if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
+                                        return rc;
+
+                                use_32bit_msi_hack = 1;
+                        }
+                } else
+                        rc = -1;
+
+                if (rc < 0)
                         rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);
 
-                if (rc < 0 && !pdn->force_32bit_msi) {
+                if (rc < 0) {
                         pr_debug("rtas_msi: trying the old firmware call.\n");
                         rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
                 }
+
+                if (use_32bit_msi_hack && rc > 0)
+                        rtas_hack_32bit_msi_gen2(pdev);
         } else
                 rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);