[SRU][F][PATCH 1/2] PCI: vmd: Add bus 224-255 restriction decode

[You-Sheng Yang]

From: Jon Derrick <jonathan.derrick at intel.com>

BugLink: https://bugs.launchpad.net/bugs/1855954

VMD bus restrictions are required when IO fabric is multiplexed such
that VMD cannot use the entire bus range. This patch adds another bus
restriction decode bit that can be set by firmware to restrict the VMD
bus range to between 224-255.

Signed-off-by: Jon Derrick <jonathan.derrick at intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
(cherry picked from commit 08bcdd22ecdb01dd60d9284a55f8220a8a40150e)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 drivers/pci/controller/vmd.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index a35d3f3996d7..15302a17ee3f 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -602,16 +602,30 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 
 	/*
 	 * Certain VMD devices may have a root port configuration option which
-	 * limits the bus range to between 0-127 or 128-255
+	 * limits the bus range to between 0-127, 128-255, or 224-255
 	 */
 	if (features & VMD_FEAT_HAS_BUS_RESTRICTIONS) {
-		u32 vmcap, vmconfig;
-
-		pci_read_config_dword(vmd->dev, PCI_REG_VMCAP, &vmcap);
-		pci_read_config_dword(vmd->dev, PCI_REG_VMCONFIG, &vmconfig);
-		if (BUS_RESTRICT_CAP(vmcap) &&
-		    (BUS_RESTRICT_CFG(vmconfig) == 0x1))
-			vmd->busn_start = 128;
+		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;
+			}
+		}
 	}
 
 	res = &vmd->dev->resource[VMD_CFGBAR];
-- 
2.25.1