[PATCH 2/6] PCI: vmd: Create bus offset configuration helper

[Jon Derrick]

Moves the bus offset configuration discovery code to a new helper.
Modifies the bus offset 2-bit decode switch to have a 0 case and a
default error case, just in case the field is expanded in future
hardware.

Reviewed-by: Andy Shevchenko <andriy.shevche...@intel.com>
Signed-off-by: Jon Derrick <jonathan.derr...@intel.com>
---
 drivers/pci/controller/vmd.c | 53 ++++++++++++++++++++++--------------
 1 file changed, 32 insertions(+), 21 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 44b2db789eff..a462719af12a 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -471,6 +471,35 @@ static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool 
native_hint,
        return 0;
 }
 
+static int vmd_get_bus_number_start(struct vmd_dev *vmd)
+{
+       struct pci_dev *dev = vmd->dev;
+       u16 reg;
+
+       pci_read_config_word(dev, PCI_REG_VMCAP, &reg);
+       if (BUS_RESTRICT_CAP(reg)) {
+               pci_read_config_word(dev, PCI_REG_VMCONFIG, &reg);
+
+               switch (BUS_RESTRICT_CFG(reg)) {
+               case 0:
+                       vmd->busn_start = 0;
+                       break;
+               case 1:
+                       vmd->busn_start = 128;
+                       break;
+               case 2:
+                       vmd->busn_start = 224;
+                       break;
+               default:
+                       pci_err(dev, "Unknown Bus Offset Setting (%d)\n",
+                               BUS_RESTRICT_CFG(reg));
+                       return -ENODEV;
+               }
+       }
+
+       return 0;
+}
+
 static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 {
        struct pci_sysdata *sd = &vmd->sysdata;
@@ -506,27 +535,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned 
long features)
         * limits the bus range to between 0-127, 128-255, or 224-255
         */
        if (features & VMD_FEAT_HAS_BUS_RESTRICTIONS) {
-               u16 reg16;
-
-               pci_read_config_word(vmd->dev, PCI_REG_VMCAP, &reg16);
-               if (BUS_RESTRICT_CAP(reg16)) {
-                       pci_read_config_word(vmd->dev, PCI_REG_VMCONFIG,
-                                            &reg16);
-
-                       switch (BUS_RESTRICT_CFG(reg16)) {
-                       case 1:
-                               vmd->busn_start = 128;
-                               break;
-                       case 2:
-                               vmd->busn_start = 224;
-                               break;
-                       case 3:
-                               pci_err(vmd->dev, "Unknown Bus Offset 
Setting\n");
-                               return -ENODEV;
-                       default:
-                               break;
-                       }
-               }
+               ret = vmd_get_bus_number_start(vmd);
+               if (ret)
+                       return ret;
        }
 
        res = &vmd->dev->resource[VMD_CFGBAR];
-- 
2.27.0