[PATCH 1/2] PCI: vmd: Reset the VMD subdevice domain on probe

[Jon Derrick <jonathan.derrick@intel.com>]

The VMD subdevice domain resource requirements may have changed
in-between module loads. Generic PCI resource assignment code may rely
on existing resource configuration rather than the VMD preference of
re-examining the domain. Add a Secondary Bus Reset to the VMD subdevice
domain during driver attachment to clear the PCI config space of the
subdevices.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 drivers/pci/controller/vmd.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 50b3520d261d..676acff3622f 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -445,6 +445,36 @@ static struct pci_ops vmd_ops = {
 	.write		= vmd_pci_write,
 };
 
+static void vmd_domain_reset_sbr(struct vmd_dev *vmd)
+{
+	char __iomem *base;
+	int rp;
+	u16 ctl;
+
+	/*
+	 * Subdevice config space is mapped linearly using 4k config space
+	 * increments. Use increments of 0x8000 to locate root ports devices.
+	 */
+	for (rp = 0; rp < 4; rp++) {
+		base = vmd->cfgbar + rp * 0x8000;
+		if (readl(base + PCI_COMMAND) == 0xFFFFFFFF)
+			continue;
+
+		/* pci_reset_secondary_bus() */
+		ctl = readw(base + PCI_BRIDGE_CONTROL);
+		ctl |= PCI_BRIDGE_CTL_BUS_RESET;
+		writew(ctl, base + PCI_BRIDGE_CONTROL);
+		readw(base + PCI_BRIDGE_CONTROL);
+		msleep(2);
+
+		ctl &= ~PCI_BRIDGE_CTL_BUS_RESET;
+		writew(ctl, base + PCI_BRIDGE_CONTROL);
+		readw(base + PCI_BRIDGE_CONTROL);
+	}
+
+	ssleep(1);
+}
+
 static void vmd_attach_resources(struct vmd_dev *vmd)
 {
 	vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[1];
@@ -784,6 +814,7 @@ static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (!vmd->cfgbar)
 		return -ENOMEM;
 
+	vmd_domain_reset_sbr(dev);
 	pci_set_master(dev);
 	if (dma_set_mask_and_coherent(&dev->dev, DMA_BIT_MASK(64)) &&
 	    dma_set_mask_and_coherent(&dev->dev, DMA_BIT_MASK(32)))
-- 
2.18.1