diff --git a/drivers/misc/cxl/Kconfig b/drivers/misc/cxl/Kconfig
index 560412c..6859723 100644
--- a/drivers/misc/cxl/Kconfig
+++ b/drivers/misc/cxl/Kconfig
@@ -38,3 +38,11 @@ config CXL
 	  CAPI adapters are found in POWER8 based systems.
 
 	  If unsure, say N.
+
+config CXL_BIMODAL
+	bool "Support for bi-modal CAPI cards"
+	depends on HOTPLUG_PCI_POWERNV = y && CXL || HOTPLUG_PCI_POWERNV = m && CXL = m
+	default y
+	help
+	  Select this option to enable support for bi-modal CAPI cards, such as
+	  the Mellanox CX-4.
\ No newline at end of file
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 090eee8..63abd26 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -55,6 +55,8 @@
 	pci_read_config_byte(dev, vsec + 0xa, dest)
 #define CXL_WRITE_VSEC_MODE_CONTROL(dev, vsec, val) \
 	pci_write_config_byte(dev, vsec + 0xa, val)
+#define CXL_WRITE_VSEC_MODE_CONTROL_BUS(bus, devfn, vsec, val) \
+	pci_bus_write_config_byte(bus, devfn, vsec + 0xa, val)
 #define CXL_VSEC_PROTOCOL_MASK   0xe0
 #define CXL_VSEC_PROTOCOL_1024TB 0x80
 #define CXL_VSEC_PROTOCOL_512TB  0x40
@@ -614,36 +616,232 @@ static int setup_cxl_bars(struct pci_dev *dev)
 	return 0;
 }
 
-/* pciex node: ibm,opal-m64-window = <0x3d058 0x0 0x3d058 0x0 0x8 0x0>; */
-static int switch_card_to_cxl(struct pci_dev *dev)
-{
+#ifdef CONFIG_CXL_BIMODAL
+
+struct cxl_switch_work {
+	struct pci_dev *dev;
+	struct work_struct work;
 	int vsec;
+	int mode;
+};
+
+static void switch_card_to_cxl(struct work_struct *work)
+{
+	struct cxl_switch_work *switch_work =
+		container_of(work, struct cxl_switch_work, work);
+	struct pci_dev *dev = switch_work->dev;
+	struct pci_bus *bus = dev->bus;
+	struct pci_controller *hose = pci_bus_to_host(bus);
+	struct pci_dev *bridge;
+	struct pnv_php_slot *php_slot;
+	unsigned int devfn;
 	u8 val;
 	int rc;
 
-	dev_info(&dev->dev, "switch card to CXL\n");
+	dev_info(&bus->dev, "cxl: Preparing for mode switch...\n");
+	bridge = list_first_entry_or_null(&hose->bus->devices, struct pci_dev,
+					  bus_list);
+	if (!bridge) {
+		dev_WARN(&bus->dev, "cxl: Couldn't find root port!\n");
+		goto err_free_work;
+	}
 
-	if (!(vsec = find_cxl_vsec(dev))) {
-		dev_err(&dev->dev, "ABORTING: CXL VSEC not found!\n");
+	php_slot = pnv_php_find_slot(pci_device_to_OF_node(bridge));
+	if (!php_slot) {
+		dev_err(&bus->dev, "cxl: Failed to find slot hotplug "
+			           "information. You may need to upgrade "
+			           "skiboot. Aborting.\n");
+		pci_dev_put(dev);
+		goto err_free_work;
+	}
+
+	rc = CXL_READ_VSEC_MODE_CONTROL(dev, switch_work->vsec, &val);
+	if (rc) {
+		dev_err(&bus->dev, "cxl: Failed to read CAPI mode control: %i\n", rc);
+		pci_dev_put(dev);
+		goto err_free_work;
+	}
+	devfn = dev->devfn;
+	pci_dev_put(dev);
+
+	dev_dbg(&bus->dev, "cxl: Removing PCI devices from kernel\n");
+	pci_lock_rescan_remove();
+	pci_hp_remove_devices(bridge->subordinate);
+	pci_unlock_rescan_remove();
+
+	/* Switch the CXL protocol on the card */
+	if (switch_work->mode == CXL_BIMODE_CXL) {
+		dev_info(&bus->dev, "cxl: Switching card to CXL mode\n");
+		val &= ~CXL_VSEC_PROTOCOL_MASK;
+		val |= CXL_VSEC_PROTOCOL_256TB | CXL_VSEC_PROTOCOL_ENABLE;
+		rc = pnv_cxl_enable_phb_kernel_api(hose, true);
+		if (rc) {
+			dev_err(&bus->dev, "cxl: Failed to enable kernel API"
+				           " on real PHB, aborting\n");
+			goto err_free_work;
+		}
+	} else {
+		dev_WARN(&bus->dev, "cxl: Switching card to PCI mode not supported!\n");
+		goto err_free_work;
+	}
+
+	rc = CXL_WRITE_VSEC_MODE_CONTROL_BUS(bus, devfn, switch_work->vsec, val);
+	if (rc) {
+		dev_err(&bus->dev, "cxl: Failed to configure CXL protocol: %i\n", rc);
+		goto err_free_work;
+	}
+
+	/*
+	 * The CAIA spec (v1.1, Section 10.6 Bi-modal Device Support) states
+	 * we must wait 100ms after this mode switch before touching PCIe config
+	 * space.
+	 */
+	msleep(100);
+
+	/*
+	 * Hot reset to cause the card to come back in cxl mode. A
+	 * OPAL_RESET_PCI_LINK would be sufficient, but currently lacks support
+	 * in skiboot, so we use a hot reset instead.
+	 *
+	 * We call pci_set_pcie_reset_state() on the bridge, as a CAPI card is
+	 * guaranteed to sit directly under the root port, and setting the reset
+	 * state on a device directly under the root port is equivalent to doing
+	 * it on the root port iself.
+	 */
+	dev_info(&bus->dev, "cxl: Configuration write complete, resetting card\n");
+	pci_set_pcie_reset_state(bridge, pcie_hot_reset);
+	pci_set_pcie_reset_state(bridge, pcie_deassert_reset);
+
+	dev_dbg(&bus->dev, "cxl: Offlining slot\n");
+	rc = pnv_php_set_slot_power_state(&php_slot->slot, OPAL_PCI_SLOT_OFFLINE);
+	if (rc) {
+		dev_err(&bus->dev, "cxl: OPAL offlining call failed: %i\n", rc);
+		goto err_free_work;
+	}
+
+	dev_dbg(&bus->dev, "cxl: Onlining and probing slot\n");
+	rc = pnv_php_set_slot_power_state(&php_slot->slot, OPAL_PCI_SLOT_ONLINE);
+	if (rc) {
+		dev_err(&bus->dev, "cxl: OPAL onlining call failed: %i\n", rc);
+		goto err_free_work;
+	}
+
+	pci_lock_rescan_remove();
+	pci_hp_add_devices(bridge->subordinate);
+	pci_unlock_rescan_remove();
+
+	dev_info(&bus->dev, "cxl: CAPI mode switch completed\n");
+	kfree(switch_work);
+	return;
+
+err_free_work:
+	kfree(switch_work);
+}
+
+int cxl_check_and_switch_mode(struct pci_dev *dev, int mode, int vsec)
+{
+	struct cxl_switch_work *work;
+	u8 val;
+	int rc;
+
+	if (!cpu_has_feature(CPU_FTR_HVMODE))
 		return -ENODEV;
+
+	if (!vsec) {
+		vsec = find_cxl_vsec(dev);
+		if (!vsec) {
+			dev_info(&dev->dev, "CXL VSEC not found\n");
+			return -ENODEV;
+		}
 	}
 
-	if ((rc = CXL_READ_VSEC_MODE_CONTROL(dev, vsec, &val))) {
-		dev_err(&dev->dev, "failed to read current mode control: %i", rc);
+	rc = CXL_READ_VSEC_MODE_CONTROL(dev, vsec, &val);
+	if (rc) {
+		dev_err(&dev->dev, "Failed to read current mode control: %i", rc);
 		return rc;
 	}
-	val &= ~CXL_VSEC_PROTOCOL_MASK;
-	val |= CXL_VSEC_PROTOCOL_256TB | CXL_VSEC_PROTOCOL_ENABLE;
-	if ((rc = CXL_WRITE_VSEC_MODE_CONTROL(dev, vsec, val))) {
-		dev_err(&dev->dev, "failed to enable CXL protocol: %i", rc);
-		return rc;
+
+	if (mode == CXL_BIMODE_PCI) {
+		if (!(val & CXL_VSEC_PROTOCOL_ENABLE)) {
+			dev_info(&dev->dev, "Card is already in PCI mode\n");
+			return 0;
+		}
+		/*
+		 * TODO: Before it's safe to switch the card back to PCI mode
+		 * we need to disable the CAPP and make sure any cachelines the
+		 * card holds have been flushed out. Needs skiboot support.
+		 */
+		dev_WARN(&dev->dev, "CXL mode switch to PCI unsupported!\n");
+		return -EIO;
 	}
+
+	if (val & CXL_VSEC_PROTOCOL_ENABLE) {
+		dev_info(&dev->dev, "Card is already in CXL mode\n");
+		return 0;
+	}
+
+	dev_info(&dev->dev, "Card is in PCI mode, scheduling kernel thread "
+			    "to switch to CXL mode\n");
+
+	work = kmalloc(sizeof(struct cxl_switch_work), GFP_KERNEL);
+	if (!work)
+		return -ENOMEM;
+
+	pci_dev_get(dev);
+	work->dev = dev;
+	work->vsec = vsec;
+	work->mode = mode;
+	INIT_WORK(&work->work, switch_card_to_cxl);
+
+	schedule_work(&work->work);
+
 	/*
-	 * The CAIA spec (v0.12 11.6 Bi-modal Device Support) states
-	 * we must wait 100ms after this mode switch before touching
-	 * PCIe config space.
+	 * We return a failure now to abort the driver init. Once the
+	 * link has been cycled and the card is in cxl mode we will
+	 * come back (possibly using the generic cxl driver), but
+	 * return success as the card should then be in cxl mode.
+	 *
+	 * TODO: What if the card comes back in PCI mode even after
+	 *       the switch?  Don't want to spin endlessly.
 	 */
-	msleep(100);
+	return -EBUSY;
+}
+EXPORT_SYMBOL_GPL(cxl_check_and_switch_mode);
+
+#endif /* CONFIG_CXL_BIMODAL */
+
+static int setup_cxl_protocol_area(struct pci_dev *dev)
+{
+	u8 val;
+	int rc;
+	int vsec = find_cxl_vsec(dev);
+
+	if (!vsec) {
+		dev_info(&dev->dev, "CXL VSEC not found\n");
+		return -ENODEV;
+	}
+
+	rc = CXL_READ_VSEC_MODE_CONTROL(dev, vsec, &val);
+	if (rc) {
+		dev_err(&dev->dev, "Failed to read current mode control: %i\n", rc);
+		return rc;
+	}
+
+	if (!(val & CXL_VSEC_PROTOCOL_ENABLE)) {
+		dev_err(&dev->dev, "Card not in CAPI mode!\n");
+		return -EIO;
+	}
+
+	/* Still configure the protocol area for single mode cards */
+	if ((val & CXL_VSEC_PROTOCOL_MASK) != CXL_VSEC_PROTOCOL_256TB) {
+		val &= ~CXL_VSEC_PROTOCOL_MASK;
+		val |= CXL_VSEC_PROTOCOL_256TB;
+		rc = CXL_WRITE_VSEC_MODE_CONTROL(dev, vsec, val);
+		if (rc) {
+			dev_err(&dev->dev, "Failed to set CXL protocol area: %i\n", rc);
+			return rc;
+		}
+	}
 
 	return 0;
 }
@@ -1249,7 +1447,7 @@ static int cxl_configure_adapter(struct cxl *adapter, struct pci_dev *dev)
 	if ((rc = setup_cxl_bars(dev)))
 		return rc;
 
-	if ((rc = switch_card_to_cxl(dev)))
+	if ((rc = setup_cxl_protocol_area(dev)))
 		return rc;
 
 	if ((rc = cxl_update_image_control(adapter)))
diff --git a/include/misc/cxl.h b/include/misc/cxl.h
index ed81a17..e5e17ed 100644
--- a/include/misc/cxl.h
+++ b/include/misc/cxl.h
@@ -39,6 +39,31 @@
 bool cxl_slot_is_supported(struct pci_dev *dev, int flags);
 
 
+#define CXL_BIMODE_CXL 1
+#define CXL_BIMODE_PCI 2
+
+/*
+ * Check the mode that the given bi-modal CXL adapter is currently in and
+ * change it if necessary. This does not apply to AFU drivers.
+ *
+ * If the mode matches the requested mode this function will return 0 - if the
+ * driver was expecting the generic CXL driver to have bound to the adapter and
+ * it gets this return value it should fail the probe function to give the CXL
+ * driver a chance to probe it.
+ *
+ * If the mode does not match it will start a background task to unplug the
+ * device from Linux and switch its mode, and will return -EBUSY. At this
+ * point the calling driver should make sure it has released the device and
+ * fail its probe function.
+ *
+ * The offset of the CXL VSEC can be provided to this function. If 0 is passed,
+ * this function will search for a CXL VSEC with ID 0x1280 and return -ENODEV
+ * if it is not found.
+ */
+#ifdef CONFIG_CXL_BIMODAL
+int cxl_check_and_switch_mode(struct pci_dev *dev, int mode, int vsec);
+#endif
+
 /* Get the AFU associated with a pci_dev */
 struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev);
 
