1 files changed, 441 insertions, 43 deletions

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index a08fcc888a71..d152e2de8c93 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
@@ -352,13 +354,10 @@ static u64 get_capp_unit_id(struct device_node *np)
 	return 0;
 }
 
-static int init_implementation_adapter_regs(struct cxl *adapter, struct pci_dev *dev)
+static int calc_capp_routing(struct pci_dev *dev, u64 *chipid, u64 *capp_unit_id)
 {
 	struct device_node *np;
 	const __be32 *prop;
-	u64 psl_dsnctl;
-	u64 chipid;
-	u64 capp_unit_id;
 
 	if (!(np = pnv_pci_get_phb_node(dev)))
 		return -ENODEV;
@@ -367,14 +366,28 @@ static int init_implementation_adapter_regs(struct cxl *adapter, struct pci_dev
 		np = of_get_next_parent(np);
 	if (!np)
 		return -ENODEV;
-	chipid = be32_to_cpup(prop);
-	capp_unit_id = get_capp_unit_id(np);
+	*chipid = be32_to_cpup(prop);
+	*capp_unit_id = get_capp_unit_id(np);
 	of_node_put(np);
-	if (!capp_unit_id) {
+	if (!*capp_unit_id) {
 		pr_err("cxl: invalid capp unit id\n");
 		return -ENODEV;
 	}
 
+	return 0;
+}
+
+static int init_implementation_adapter_psl_regs(struct cxl *adapter, struct pci_dev *dev)
+{
+	u64 psl_dsnctl;
+	u64 chipid;
+	u64 capp_unit_id;
+	int rc;
+
+	rc = calc_capp_routing(dev, &chipid, &capp_unit_id);
+	if (rc)
+		return rc;
+
 	psl_dsnctl = 0x0000900000000000ULL; /* pteupd ttype, scdone */
 	psl_dsnctl |= (0x2ULL << (63-38)); /* MMIO hang pulse: 256 us */
 	/* Tell PSL where to route data to */
@@ -393,8 +406,61 @@ static int init_implementation_adapter_regs(struct cxl *adapter, struct pci_dev
 	return 0;
 }
 
+static int init_implementation_adapter_xsl_regs(struct cxl *adapter, struct pci_dev *dev)
+{
+	u64 xsl_dsnctl;
+	u64 chipid;
+	u64 capp_unit_id;
+	int rc;
+
+	rc = calc_capp_routing(dev, &chipid, &capp_unit_id);
+	if (rc)
+		return rc;
+
+	/* Tell XSL where to route data to */
+	xsl_dsnctl = 0x0000600000000000ULL | (chipid << (63-5));
+	xsl_dsnctl |= (capp_unit_id << (63-13));
+	cxl_p1_write(adapter, CXL_XSL_DSNCTL, xsl_dsnctl);
+
+	return 0;
+}
+
+/* PSL & XSL */
+#define TBSYNC_CAL(n) (((u64)n & 0x7) << (63-3))
 #define TBSYNC_CNT(n) (((u64)n & 0x7) << (63-6))
-#define _2048_250MHZ_CYCLES 1
+/* For the PSL this is a multiple for 0 < n <= 7: */
+#define PSL_2048_250MHZ_CYCLES 1
+
+static void write_timebase_ctrl_psl(struct cxl *adapter)
+{
+	cxl_p1_write(adapter, CXL_PSL_TB_CTLSTAT,
+		     TBSYNC_CNT(2 * PSL_2048_250MHZ_CYCLES));
+}
+
+/* XSL */
+#define TBSYNC_ENA (1ULL << 63)
+/* For the XSL this is 2**n * 2000 clocks for 0 < n <= 6: */
+#define XSL_2000_CLOCKS 1
+#define XSL_4000_CLOCKS 2
+#define XSL_8000_CLOCKS 3
+
+static void write_timebase_ctrl_xsl(struct cxl *adapter)
+{
+	cxl_p1_write(adapter, CXL_XSL_TB_CTLSTAT,
+		     TBSYNC_ENA |
+		     TBSYNC_CAL(3) |
+		     TBSYNC_CNT(XSL_4000_CLOCKS));
+}
+
+static u64 timebase_read_psl(struct cxl *adapter)
+{
+	return cxl_p1_read(adapter, CXL_PSL_Timebase);
+}
+
+static u64 timebase_read_xsl(struct cxl *adapter)
+{
+	return cxl_p1_read(adapter, CXL_XSL_Timebase);
+}
 
 static void cxl_setup_psl_timebase(struct cxl *adapter, struct pci_dev *dev)
 {
@@ -421,8 +487,7 @@ static void cxl_setup_psl_timebase(struct cxl *adapter, struct pci_dev *dev)
 	 * Setup PSL Timebase Control and Status register
 	 * with the recommended Timebase Sync Count value
 	 */
-	cxl_p1_write(adapter, CXL_PSL_TB_CTLSTAT,
-		     TBSYNC_CNT(2 * _2048_250MHZ_CYCLES));
+	adapter->native->sl_ops->write_timebase_ctrl(adapter);
 
 	/* Enable PSL Timebase */
 	cxl_p1_write(adapter, CXL_PSL_Control, 0x0000000000000000);
@@ -435,7 +500,7 @@ static void cxl_setup_psl_timebase(struct cxl *adapter, struct pci_dev *dev)
 			dev_info(&dev->dev, "PSL timebase can't synchronize\n");
 			return;
 		}
-		psl_tb = cxl_p1_read(adapter, CXL_PSL_Timebase);
+		psl_tb = adapter->native->sl_ops->timebase_read(adapter);
 		delta = mftb() - psl_tb;
 		if (delta < 0)
 			delta = -delta;
@@ -445,7 +510,7 @@ static void cxl_setup_psl_timebase(struct cxl *adapter, struct pci_dev *dev)
 	return;
 }
 
-static int init_implementation_afu_regs(struct cxl_afu *afu)
+static int init_implementation_afu_psl_regs(struct cxl_afu *afu)
 {
 	/* read/write masks for this slice */
 	cxl_p1n_write(afu, CXL_PSL_APCALLOC_A, 0xFFFFFFFEFEFEFEFEULL);
@@ -551,36 +616,234 @@ 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_dev_put;
+	}
 
-	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");
+		goto err_dev_put;
+	}
+
+	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);
+		goto err_dev_put;
+	}
+	devfn = dev->devfn;
+
+	/* Release the reference obtained in cxl_check_and_switch_mode() */
+	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_dev_put:
+	/* Release the reference obtained in cxl_check_and_switch_mode() */
+	pci_dev_put(dev);
+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;
+	}
+
+	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;
 }
@@ -712,6 +975,21 @@ static int cxl_afu_descriptor_looks_ok(struct cxl_afu *afu)
 		}
 	}
 
+	if ((afu->modes_supported & ~CXL_MODE_DEDICATED) && afu->max_procs_virtualised == 0) {
+		/*
+		 * We could also check this for the dedicated process model
+		 * since the architecture indicates it should be set to 1, but
+		 * in that case we ignore the value and I'd rather not risk
+		 * breaking any existing dedicated process AFUs that left it as
+		 * 0 (not that I'm aware of any). It is clearly an error for an
+		 * AFU directed AFU to set this to 0, and would have previously
+		 * triggered a bug resulting in the maximum not being enforced
+		 * at all since idr_alloc treats 0 as no maximum.
+		 */
+		dev_err(&afu->dev, "AFU does not support any processes\n");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -753,11 +1031,13 @@ static int sanitise_afu_regs(struct cxl_afu *afu)
 		else
 			cxl_p2n_write(afu, CXL_PSL_TFC_An, CXL_PSL_TFC_An_A);
 	}
-	reg = cxl_p1n_read(afu, CXL_PSL_SERR_An);
-	if (reg) {
-		if (reg & ~0xffff)
-			dev_warn(&afu->dev, "AFU had pending SERR: %#016llx\n", reg);
-		cxl_p1n_write(afu, CXL_PSL_SERR_An, reg & ~0xffff);
+	if (afu->adapter->native->sl_ops->register_serr_irq) {
+		reg = cxl_p1n_read(afu, CXL_PSL_SERR_An);
+		if (reg) {
+			if (reg & ~0xffff)
+				dev_warn(&afu->dev, "AFU had pending SERR: %#016llx\n", reg);
+			cxl_p1n_write(afu, CXL_PSL_SERR_An, reg & ~0xffff);
+		}
 	}
 	reg = cxl_p2n_read(afu, CXL_PSL_ErrStat_An);
 	if (reg) {
@@ -835,11 +1115,13 @@ static int pci_configure_afu(struct cxl_afu *afu, struct cxl *adapter, struct pc
 	if ((rc = cxl_afu_descriptor_looks_ok(afu)))
 		goto err1;
 
-	if ((rc = init_implementation_afu_regs(afu)))
-		goto err1;
+	if (adapter->native->sl_ops->afu_regs_init)
+		if ((rc = adapter->native->sl_ops->afu_regs_init(afu)))
+			goto err1;
 
-	if ((rc = cxl_native_register_serr_irq(afu)))
-		goto err1;
+	if (adapter->native->sl_ops->register_serr_irq)
+		if ((rc = adapter->native->sl_ops->register_serr_irq(afu)))
+			goto err1;
 
 	if ((rc = cxl_native_register_psl_irq(afu)))
 		goto err2;
@@ -847,7 +1129,8 @@ static int pci_configure_afu(struct cxl_afu *afu, struct cxl *adapter, struct pc
 	return 0;
 
 err2:
-	cxl_native_release_serr_irq(afu);
+	if (adapter->native->sl_ops->release_serr_irq)
+		adapter->native->sl_ops->release_serr_irq(afu);
 err1:
 	pci_unmap_slice_regs(afu);
 	return rc;
@@ -856,7 +1139,8 @@ err1:
 static void pci_deconfigure_afu(struct cxl_afu *afu)
 {
 	cxl_native_release_psl_irq(afu);
-	cxl_native_release_serr_irq(afu);
+	if (afu->adapter->native->sl_ops->release_serr_irq)
+		afu->adapter->native->sl_ops->release_serr_irq(afu);
 	pci_unmap_slice_regs(afu);
 }
 
@@ -1165,7 +1449,7 @@ 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)))
@@ -1177,10 +1461,13 @@ static int cxl_configure_adapter(struct cxl *adapter, struct pci_dev *dev)
 	if ((rc = sanitise_adapter_regs(adapter)))
 		goto err;
 
-	if ((rc = init_implementation_adapter_regs(adapter, dev)))
+	if ((rc = adapter->native->sl_ops->adapter_regs_init(adapter, dev)))
 		goto err;
 
-	if ((rc = pnv_phb_to_cxl_mode(dev, OPAL_PHB_CAPI_MODE_CAPI)))
+	/* Required for devices using CAPP DMA mode, harmless for others */
+	pci_set_master(dev);
+
+	if ((rc = pnv_phb_to_cxl_mode(dev, adapter->native->sl_ops->capi_mode)))
 		goto err;
 
 	/* If recovery happened, the last step is to turn on snooping.
@@ -1212,6 +1499,43 @@ static void cxl_deconfigure_adapter(struct cxl *adapter)
 	pci_disable_device(pdev);
 }
 
+static const struct cxl_service_layer_ops psl_ops = {
+	.adapter_regs_init = init_implementation_adapter_psl_regs,
+	.afu_regs_init = init_implementation_afu_psl_regs,
+	.register_serr_irq = cxl_native_register_serr_irq,
+	.release_serr_irq = cxl_native_release_serr_irq,
+	.debugfs_add_adapter_sl_regs = cxl_debugfs_add_adapter_psl_regs,
+	.debugfs_add_afu_sl_regs = cxl_debugfs_add_afu_psl_regs,
+	.psl_irq_dump_registers = cxl_native_psl_irq_dump_regs,
+	.err_irq_dump_registers = cxl_native_err_irq_dump_regs,
+	.debugfs_stop_trace = cxl_stop_trace,
+	.write_timebase_ctrl = write_timebase_ctrl_psl,
+	.timebase_read = timebase_read_psl,
+	.capi_mode = OPAL_PHB_CAPI_MODE_CAPI,
+	.needs_reset_before_disable = true,
+};
+
+static const struct cxl_service_layer_ops xsl_ops = {
+	.adapter_regs_init = init_implementation_adapter_xsl_regs,
+	.debugfs_add_adapter_sl_regs = cxl_debugfs_add_adapter_xsl_regs,
+	.write_timebase_ctrl = write_timebase_ctrl_xsl,
+	.timebase_read = timebase_read_xsl,
+	.capi_mode = OPAL_PHB_CAPI_MODE_DMA,
+	.min_pe = 1, /* Workaround for Mellanox CX4 HW bug */
+};
+
+static void set_sl_ops(struct cxl *adapter, struct pci_dev *dev)
+{
+	if (dev->vendor == PCI_VENDOR_ID_MELLANOX && dev->device == 0x1013) {
+		dev_info(&adapter->dev, "Device uses an XSL\n");
+		adapter->native->sl_ops = &xsl_ops;
+	} else {
+		dev_info(&adapter->dev, "Device uses a PSL\n");
+		adapter->native->sl_ops = &psl_ops;
+	}
+}
+
+
 static struct cxl *cxl_pci_init_adapter(struct pci_dev *dev)
 {
 	struct cxl *adapter;
@@ -1227,6 +1551,8 @@ static struct cxl *cxl_pci_init_adapter(struct pci_dev *dev)
 		goto err_release;
 	}
 
+	set_sl_ops(adapter, dev);
+
 	/* Set defaults for parameters which need to persist over
 	 * configure/reconfigure
 	 */
@@ -1280,6 +1606,67 @@ static void cxl_pci_remove_adapter(struct cxl *adapter)
 	device_unregister(&adapter->dev);
 }
 
+#define CXL_MAX_PCIEX_PARENT 2
+
+static int cxl_slot_is_switched(struct pci_dev *dev)
+{
+	struct device_node *np;
+	int depth = 0;
+	const __be32 *prop;
+
+	if (!(np = pci_device_to_OF_node(dev))) {
+		pr_err("cxl: np = NULL\n");
+		return -ENODEV;
+	}
+	of_node_get(np);
+	while (np) {
+		np = of_get_next_parent(np);
+		prop = of_get_property(np, "device_type", NULL);
+		if (!prop || strcmp((char *)prop, "pciex"))
+			break;
+		depth++;
+	}
+	of_node_put(np);
+	return (depth > CXL_MAX_PCIEX_PARENT);
+}
+
+bool cxl_slot_is_supported(struct pci_dev *dev, int flags)
+{
+	if (!cpu_has_feature(CPU_FTR_HVMODE))
+		return false;
+
+	if ((flags & CXL_SLOT_FLAG_DMA) && (!pvr_version_is(PVR_POWER8NVL))) {
+		/*
+		 * CAPP DMA mode is technically supported on regular P8, but
+		 * will EEH if the card attempts to access memory < 4GB, which
+		 * we cannot realistically avoid. We might be able to work
+		 * around the issue, but until then return unsupported:
+		 */
+		return false;
+	}
+
+	if (cxl_slot_is_switched(dev))
+		return false;
+
+	/*
+	 * XXX: This gets a little tricky on regular P8 (not POWER8NVL) since
+	 * the CAPP can be connected to PHB 0, 1 or 2 on a first come first
+	 * served basis, which is racy to check from here. If we need to
+	 * support this in future we might need to consider having this
+	 * function effectively reserve it ahead of time.
+	 *
+	 * Currently, the only user of this API is the Mellanox CX4, which is
+	 * only supported on P8NVL due to the above mentioned limitation of
+	 * CAPP DMA mode and therefore does not need to worry about this. If the
+	 * issue with CAPP DMA mode is later worked around on P8 we might need
+	 * to revisit this.
+	 */
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(cxl_slot_is_supported);
+
+
 static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	struct cxl *adapter;
@@ -1291,6 +1678,11 @@ static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
 		return -ENODEV;
 	}
 
+	if (cxl_slot_is_switched(dev)) {
+		dev_info(&dev->dev, "Ignoring card on incompatible PCI slot\n");
+		return -ENODEV;
+	}
+
 	if (cxl_verbose)
 		dump_cxl_config_space(dev);
 
@@ -1311,6 +1703,9 @@ static int cxl_probe(struct pci_dev *dev, const struct pci_device_id *id)
 			dev_err(&dev->dev, "AFU %i failed to start: %i\n", slice, rc);
 	}
 
+	if (pnv_pci_on_cxl_phb(dev) && adapter->slices >= 1)
+		pnv_cxl_phb_set_peer_afu(dev, adapter->afu[0]);
+
 	return 0;
 }
 
@@ -1381,6 +1776,9 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
 		 */
 		for (i = 0; i < adapter->slices; i++) {
 			afu = adapter->afu[i];
+			/* Only participate in EEH if we are on a virtual PHB */
+			if (afu->phb == NULL)
+				return PCI_ERS_RESULT_NONE;
 			cxl_vphb_error_detected(afu, state);
 		}
 		return PCI_ERS_RESULT_DISCONNECT;