Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 717 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/sgi_hotplug.c b/drivers/pci/hotplug/sgi_hotplug.c
new file mode 100644
index 000000000..babd23409
--- /dev/null
+++ b/drivers/pci/hotplug/sgi_hotplug.c
@@ -0,0 +1,717 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005-2006 Silicon Graphics, Inc. All rights reserved.
+ *
+ * This work was based on the 2.4/2.6 kernel development by Dick Reigner.
+ * Work to add BIOS PROM support was completed by Mike Habeck.
+ */
+
+#include <linux/acpi.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pci_hotplug.h>
+#include <linux/proc_fs.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/mutex.h>
+
+#include <asm/sn/addrs.h>
+#include <asm/sn/geo.h>
+#include <asm/sn/l1.h>
+#include <asm/sn/module.h>
+#include <asm/sn/pcibr_provider.h>
+#include <asm/sn/pcibus_provider_defs.h>
+#include <asm/sn/pcidev.h>
+#include <asm/sn/sn_feature_sets.h>
+#include <asm/sn/sn_sal.h>
+#include <asm/sn/types.h>
+#include <asm/sn/acpi.h>
+
+#include "../pci.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("SGI (prarit@sgi.com, dickie@sgi.com, habeck@sgi.com)");
+MODULE_DESCRIPTION("SGI Altix Hot Plug PCI Controller Driver");
+
+
+/* SAL call error codes. Keep in sync with prom header io/include/pcibr.h */
+#define PCI_SLOT_ALREADY_UP		2	/* slot already up */
+#define PCI_SLOT_ALREADY_DOWN		3	/* slot already down */
+#define PCI_L1_ERR			7	/* L1 console command error */
+#define PCI_EMPTY_33MHZ			15	/* empty 33 MHz bus */
+
+
+#define PCIIO_ASIC_TYPE_TIOCA		4
+#define PCI_L1_QSIZE			128	/* our L1 message buffer size */
+#define SN_MAX_HP_SLOTS			32	/* max hotplug slots */
+#define SN_SLOT_NAME_SIZE		33	/* size of name string */
+
+/* internal list head */
+static struct list_head sn_hp_list;
+
+/* hotplug_slot struct's private pointer */
+struct slot {
+	int device_num;
+	struct pci_bus *pci_bus;
+	/* this struct for glue internal only */
+	struct hotplug_slot *hotplug_slot;
+	struct list_head hp_list;
+	char physical_path[SN_SLOT_NAME_SIZE];
+};
+
+struct pcibr_slot_enable_resp {
+	int resp_sub_errno;
+	char resp_l1_msg[PCI_L1_QSIZE + 1];
+};
+
+struct pcibr_slot_disable_resp {
+	int resp_sub_errno;
+	char resp_l1_msg[PCI_L1_QSIZE + 1];
+};
+
+enum sn_pci_req_e {
+	PCI_REQ_SLOT_ELIGIBLE,
+	PCI_REQ_SLOT_DISABLE
+};
+
+static int enable_slot(struct hotplug_slot *slot);
+static int disable_slot(struct hotplug_slot *slot);
+static inline int get_power_status(struct hotplug_slot *slot, u8 *value);
+
+static struct hotplug_slot_ops sn_hotplug_slot_ops = {
+	.enable_slot            = enable_slot,
+	.disable_slot           = disable_slot,
+	.get_power_status       = get_power_status,
+};
+
+static DEFINE_MUTEX(sn_hotplug_mutex);
+
+static ssize_t path_show(struct pci_slot *pci_slot, char *buf)
+{
+	int retval = -ENOENT;
+	struct slot *slot = pci_slot->hotplug->private;
+
+	if (!slot)
+		return retval;
+
+	retval = sprintf(buf, "%s\n", slot->physical_path);
+	return retval;
+}
+
+static struct pci_slot_attribute sn_slot_path_attr = __ATTR_RO(path);
+
+static int sn_pci_slot_valid(struct pci_bus *pci_bus, int device)
+{
+	struct pcibus_info *pcibus_info;
+	u16 busnum, segment, ioboard_type;
+
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(pci_bus);
+
+	/* Check to see if this is a valid slot on 'pci_bus' */
+	if (!(pcibus_info->pbi_valid_devices & (1 << device)))
+		return -EPERM;
+
+	ioboard_type = sn_ioboard_to_pci_bus(pci_bus);
+	busnum = pcibus_info->pbi_buscommon.bs_persist_busnum;
+	segment = pci_domain_nr(pci_bus) & 0xf;
+
+	/* Do not allow hotplug operations on base I/O cards */
+	if ((ioboard_type == L1_BRICKTYPE_IX ||
+	     ioboard_type == L1_BRICKTYPE_IA) &&
+	    (segment == 1 && busnum == 0 && device != 1))
+		return -EPERM;
+
+	return 1;
+}
+
+static int sn_pci_bus_valid(struct pci_bus *pci_bus)
+{
+	struct pcibus_info *pcibus_info;
+	u32 asic_type;
+	u16 ioboard_type;
+
+	/* Don't register slots hanging off the TIOCA bus */
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(pci_bus);
+	asic_type = pcibus_info->pbi_buscommon.bs_asic_type;
+	if (asic_type == PCIIO_ASIC_TYPE_TIOCA)
+		return -EPERM;
+
+	/* Only register slots in I/O Bricks that support hotplug */
+	ioboard_type = sn_ioboard_to_pci_bus(pci_bus);
+	switch (ioboard_type) {
+		case L1_BRICKTYPE_IX:
+		case L1_BRICKTYPE_PX:
+		case L1_BRICKTYPE_IA:
+		case L1_BRICKTYPE_PA:
+		case L1_BOARDTYPE_PCIX3SLOT:
+			return 1;
+			break;
+		default:
+			return -EPERM;
+			break;
+	}
+
+	return -EIO;
+}
+
+static int sn_hp_slot_private_alloc(struct hotplug_slot *bss_hotplug_slot,
+				    struct pci_bus *pci_bus, int device,
+				    char *name)
+{
+	struct pcibus_info *pcibus_info;
+	struct slot *slot;
+
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(pci_bus);
+
+	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
+	if (!slot)
+		return -ENOMEM;
+	bss_hotplug_slot->private = slot;
+
+	slot->device_num = device;
+	slot->pci_bus = pci_bus;
+	sprintf(name, "%04x:%02x:%02x",
+		pci_domain_nr(pci_bus),
+		((u16)pcibus_info->pbi_buscommon.bs_persist_busnum),
+		device + 1);
+
+	sn_generate_path(pci_bus, slot->physical_path);
+
+	slot->hotplug_slot = bss_hotplug_slot;
+	list_add(&slot->hp_list, &sn_hp_list);
+
+	return 0;
+}
+
+static struct hotplug_slot *sn_hp_destroy(void)
+{
+	struct slot *slot;
+	struct pci_slot *pci_slot;
+	struct hotplug_slot *bss_hotplug_slot = NULL;
+
+	list_for_each_entry(slot, &sn_hp_list, hp_list) {
+		bss_hotplug_slot = slot->hotplug_slot;
+		pci_slot = bss_hotplug_slot->pci_slot;
+		list_del(&((struct slot *)bss_hotplug_slot->private)->
+			 hp_list);
+		sysfs_remove_file(&pci_slot->kobj,
+				  &sn_slot_path_attr.attr);
+		break;
+	}
+	return bss_hotplug_slot;
+}
+
+static void sn_bus_free_data(struct pci_dev *dev)
+{
+	struct pci_bus *subordinate_bus;
+	struct pci_dev *child;
+
+	/* Recursively clean up sn_irq_info structs */
+	if (dev->subordinate) {
+		subordinate_bus = dev->subordinate;
+		list_for_each_entry(child, &subordinate_bus->devices, bus_list)
+			sn_bus_free_data(child);
+	}
+	/*
+	 * Some drivers may use dma accesses during the
+	 * driver remove function. We release the sysdata
+	 * areas after the driver remove functions have
+	 * been called.
+	 */
+	sn_bus_store_sysdata(dev);
+	sn_pci_unfixup_slot(dev);
+}
+
+static int sn_slot_enable(struct hotplug_slot *bss_hotplug_slot,
+			  int device_num, char **ssdt)
+{
+	struct slot *slot = bss_hotplug_slot->private;
+	struct pcibus_info *pcibus_info;
+	struct pcibr_slot_enable_resp resp;
+	int rc;
+
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
+
+	/*
+	 * Power-on and initialize the slot in the SN
+	 * PCI infrastructure.
+	 */
+	rc = sal_pcibr_slot_enable(pcibus_info, device_num, &resp, ssdt);
+
+
+	if (rc == PCI_SLOT_ALREADY_UP) {
+		pci_dbg(slot->pci_bus->self, "is already active\n");
+		return 1; /* return 1 to user */
+	}
+
+	if (rc == PCI_L1_ERR) {
+		pci_dbg(slot->pci_bus->self, "L1 failure %d with message: %s",
+			resp.resp_sub_errno, resp.resp_l1_msg);
+		return -EPERM;
+	}
+
+	if (rc) {
+		pci_dbg(slot->pci_bus->self, "insert failed with error %d sub-error %d\n",
+			rc, resp.resp_sub_errno);
+		return -EIO;
+	}
+
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
+	pcibus_info->pbi_enabled_devices |= (1 << device_num);
+
+	return 0;
+}
+
+static int sn_slot_disable(struct hotplug_slot *bss_hotplug_slot,
+			   int device_num, int action)
+{
+	struct slot *slot = bss_hotplug_slot->private;
+	struct pcibus_info *pcibus_info;
+	struct pcibr_slot_disable_resp resp;
+	int rc;
+
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
+
+	rc = sal_pcibr_slot_disable(pcibus_info, device_num, action, &resp);
+
+	if ((action == PCI_REQ_SLOT_ELIGIBLE) &&
+	    (rc == PCI_SLOT_ALREADY_DOWN)) {
+		pci_dbg(slot->pci_bus->self, "Slot %s already inactive\n", slot->physical_path);
+		return 1; /* return 1 to user */
+	}
+
+	if ((action == PCI_REQ_SLOT_ELIGIBLE) && (rc == PCI_EMPTY_33MHZ)) {
+		pci_dbg(slot->pci_bus->self, "Cannot remove last 33MHz card\n");
+		return -EPERM;
+	}
+
+	if ((action == PCI_REQ_SLOT_ELIGIBLE) && (rc == PCI_L1_ERR)) {
+		pci_dbg(slot->pci_bus->self, "L1 failure %d with message \n%s\n",
+			resp.resp_sub_errno, resp.resp_l1_msg);
+		return -EPERM;
+	}
+
+	if ((action == PCI_REQ_SLOT_ELIGIBLE) && rc) {
+		pci_dbg(slot->pci_bus->self, "remove failed with error %d sub-error %d\n",
+			rc, resp.resp_sub_errno);
+		return -EIO;
+	}
+
+	if ((action == PCI_REQ_SLOT_ELIGIBLE) && !rc)
+		return 0;
+
+	if ((action == PCI_REQ_SLOT_DISABLE) && !rc) {
+		pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
+		pcibus_info->pbi_enabled_devices &= ~(1 << device_num);
+		pci_dbg(slot->pci_bus->self, "remove successful\n");
+		return 0;
+	}
+
+	if ((action == PCI_REQ_SLOT_DISABLE) && rc) {
+		pci_dbg(slot->pci_bus->self, "remove failed rc = %d\n", rc);
+	}
+
+	return rc;
+}
+
+/*
+ * Power up and configure the slot via a SAL call to PROM.
+ * Scan slot (and any children), do any platform specific fixup,
+ * and find device driver.
+ */
+static int enable_slot(struct hotplug_slot *bss_hotplug_slot)
+{
+	struct slot *slot = bss_hotplug_slot->private;
+	struct pci_bus *new_bus = NULL;
+	struct pci_dev *dev;
+	int num_funcs;
+	int new_ppb = 0;
+	int rc;
+	char *ssdt = NULL;
+	void pcibios_fixup_device_resources(struct pci_dev *);
+
+	/* Serialize the Linux PCI infrastructure */
+	mutex_lock(&sn_hotplug_mutex);
+
+	/*
+	 * Power-on and initialize the slot in the SN
+	 * PCI infrastructure. Also, retrieve the ACPI SSDT
+	 * table for the slot (if ACPI capable PROM).
+	 */
+	rc = sn_slot_enable(bss_hotplug_slot, slot->device_num, &ssdt);
+	if (rc) {
+		mutex_unlock(&sn_hotplug_mutex);
+		return rc;
+	}
+
+	if (ssdt)
+		ssdt = __va(ssdt);
+	/* Add the new SSDT for the slot to the ACPI namespace */
+	if (SN_ACPI_BASE_SUPPORT() && ssdt) {
+		acpi_status ret;
+
+		ret = acpi_load_table((struct acpi_table_header *)ssdt);
+		if (ACPI_FAILURE(ret)) {
+			printk(KERN_ERR "%s: acpi_load_table failed (0x%x)\n",
+			       __func__, ret);
+			/* try to continue on */
+		}
+	}
+
+	num_funcs = pci_scan_slot(slot->pci_bus,
+				  PCI_DEVFN(slot->device_num + 1, 0));
+	if (!num_funcs) {
+		pci_dbg(slot->pci_bus->self, "no device in slot\n");
+		mutex_unlock(&sn_hotplug_mutex);
+		return -ENODEV;
+	}
+
+	/*
+	 * Map SN resources for all functions on the card
+	 * to the Linux PCI interface and tell the drivers
+	 * about them.
+	 */
+	list_for_each_entry(dev, &slot->pci_bus->devices, bus_list) {
+		if (PCI_SLOT(dev->devfn) != slot->device_num + 1)
+			continue;
+
+		/* Need to do slot fixup on PPB before fixup of children
+		 * (PPB's pcidev_info needs to be in pcidev_info list
+		 * before child's SN_PCIDEV_INFO() call to setup
+		 * pdi_host_pcidev_info).
+		 */
+		pcibios_fixup_device_resources(dev);
+		if (SN_ACPI_BASE_SUPPORT())
+			sn_acpi_slot_fixup(dev);
+		else
+			sn_io_slot_fixup(dev);
+		if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
+			pci_hp_add_bridge(dev);
+			if (dev->subordinate) {
+				new_bus = dev->subordinate;
+				new_ppb = 1;
+			}
+		}
+	}
+
+	/*
+	 * Add the slot's devices to the ACPI infrastructure */
+	if (SN_ACPI_BASE_SUPPORT() && ssdt) {
+		unsigned long long adr;
+		struct acpi_device *pdevice;
+		acpi_handle phandle;
+		acpi_handle chandle = NULL;
+		acpi_handle rethandle;
+		acpi_status ret;
+
+		phandle = acpi_device_handle(PCI_CONTROLLER(slot->pci_bus)->companion);
+
+		if (acpi_bus_get_device(phandle, &pdevice)) {
+			pci_dbg(slot->pci_bus->self, "no parent device, assuming NULL\n");
+			pdevice = NULL;
+		}
+
+		acpi_scan_lock_acquire();
+		/*
+		 * Walk the rootbus node's immediate children looking for
+		 * the slot's device node(s). There can be more than
+		 * one for multifunction devices.
+		 */
+		for (;;) {
+			rethandle = NULL;
+			ret = acpi_get_next_object(ACPI_TYPE_DEVICE,
+						   phandle, chandle,
+						   &rethandle);
+
+			if (ret == AE_NOT_FOUND || rethandle == NULL)
+				break;
+
+			chandle = rethandle;
+
+			ret = acpi_evaluate_integer(chandle, METHOD_NAME__ADR,
+						    NULL, &adr);
+
+			if (ACPI_SUCCESS(ret) &&
+			    (adr>>16) == (slot->device_num + 1)) {
+
+				ret = acpi_bus_scan(chandle);
+				if (ACPI_FAILURE(ret)) {
+					printk(KERN_ERR "%s: acpi_bus_scan failed (0x%x) for slot %d func %d\n",
+					       __func__, ret, (int)(adr>>16),
+					       (int)(adr&0xffff));
+					/* try to continue on */
+				}
+			}
+		}
+		acpi_scan_lock_release();
+	}
+
+	pci_lock_rescan_remove();
+
+	/* Call the driver for the new device */
+	pci_bus_add_devices(slot->pci_bus);
+	/* Call the drivers for the new devices subordinate to PPB */
+	if (new_ppb)
+		pci_bus_add_devices(new_bus);
+
+	pci_unlock_rescan_remove();
+	mutex_unlock(&sn_hotplug_mutex);
+
+	if (rc == 0)
+		pci_dbg(slot->pci_bus->self, "insert operation successful\n");
+	else
+		pci_dbg(slot->pci_bus->self, "insert operation failed rc = %d\n", rc);
+
+	return rc;
+}
+
+static int disable_slot(struct hotplug_slot *bss_hotplug_slot)
+{
+	struct slot *slot = bss_hotplug_slot->private;
+	struct pci_dev *dev, *temp;
+	int rc;
+	acpi_handle ssdt_hdl = NULL;
+
+	/* Acquire update access to the bus */
+	mutex_lock(&sn_hotplug_mutex);
+
+	/* is it okay to bring this slot down? */
+	rc = sn_slot_disable(bss_hotplug_slot, slot->device_num,
+			     PCI_REQ_SLOT_ELIGIBLE);
+	if (rc)
+		goto leaving;
+
+	/* free the ACPI resources for the slot */
+	if (SN_ACPI_BASE_SUPPORT() &&
+		PCI_CONTROLLER(slot->pci_bus)->companion) {
+		unsigned long long adr;
+		struct acpi_device *device;
+		acpi_handle phandle;
+		acpi_handle chandle = NULL;
+		acpi_handle rethandle;
+		acpi_status ret;
+
+		/* Get the rootbus node pointer */
+		phandle = acpi_device_handle(PCI_CONTROLLER(slot->pci_bus)->companion);
+
+		acpi_scan_lock_acquire();
+		/*
+		 * Walk the rootbus node's immediate children looking for
+		 * the slot's device node(s). There can be more than
+		 * one for multifunction devices.
+		 */
+		for (;;) {
+			rethandle = NULL;
+			ret = acpi_get_next_object(ACPI_TYPE_DEVICE,
+						   phandle, chandle,
+						   &rethandle);
+
+			if (ret == AE_NOT_FOUND || rethandle == NULL)
+				break;
+
+			chandle = rethandle;
+
+			ret = acpi_evaluate_integer(chandle,
+						    METHOD_NAME__ADR,
+						    NULL, &adr);
+			if (ACPI_SUCCESS(ret) &&
+			    (adr>>16) == (slot->device_num + 1)) {
+				/* retain the owner id */
+				ssdt_hdl = chandle;
+
+				ret = acpi_bus_get_device(chandle,
+							  &device);
+				if (ACPI_SUCCESS(ret))
+					acpi_bus_trim(device);
+			}
+		}
+		acpi_scan_lock_release();
+	}
+
+	pci_lock_rescan_remove();
+	/* Free the SN resources assigned to the Linux device.*/
+	list_for_each_entry_safe(dev, temp, &slot->pci_bus->devices, bus_list) {
+		if (PCI_SLOT(dev->devfn) != slot->device_num + 1)
+			continue;
+
+		pci_dev_get(dev);
+		sn_bus_free_data(dev);
+		pci_stop_and_remove_bus_device(dev);
+		pci_dev_put(dev);
+	}
+	pci_unlock_rescan_remove();
+
+	/* Remove the SSDT for the slot from the ACPI namespace */
+	if (SN_ACPI_BASE_SUPPORT() && ssdt_hdl) {
+		acpi_status ret;
+		ret = acpi_unload_parent_table(ssdt_hdl);
+		if (ACPI_FAILURE(ret)) {
+			acpi_handle_err(ssdt_hdl,
+					"%s: acpi_unload_parent_table failed (0x%x)\n",
+					__func__, ret);
+			/* try to continue on */
+		}
+	}
+
+	/* free the collected sysdata pointers */
+	sn_bus_free_sysdata();
+
+	/* Deactivate slot */
+	rc = sn_slot_disable(bss_hotplug_slot, slot->device_num,
+			     PCI_REQ_SLOT_DISABLE);
+ leaving:
+	/* Release the bus lock */
+	mutex_unlock(&sn_hotplug_mutex);
+
+	return rc;
+}
+
+static inline int get_power_status(struct hotplug_slot *bss_hotplug_slot,
+				   u8 *value)
+{
+	struct slot *slot = bss_hotplug_slot->private;
+	struct pcibus_info *pcibus_info;
+	u32 power;
+
+	pcibus_info = SN_PCIBUS_BUSSOFT_INFO(slot->pci_bus);
+	mutex_lock(&sn_hotplug_mutex);
+	power = pcibus_info->pbi_enabled_devices & (1 << slot->device_num);
+	*value = power ? 1 : 0;
+	mutex_unlock(&sn_hotplug_mutex);
+	return 0;
+}
+
+static void sn_release_slot(struct hotplug_slot *bss_hotplug_slot)
+{
+	kfree(bss_hotplug_slot->info);
+	kfree(bss_hotplug_slot->private);
+	kfree(bss_hotplug_slot);
+}
+
+static int sn_hotplug_slot_register(struct pci_bus *pci_bus)
+{
+	int device;
+	struct pci_slot *pci_slot;
+	struct hotplug_slot *bss_hotplug_slot;
+	char name[SN_SLOT_NAME_SIZE];
+	int rc = 0;
+
+	/*
+	 * Currently only four devices are supported,
+	 * in the future there maybe more -- up to 32.
+	 */
+
+	for (device = 0; device < SN_MAX_HP_SLOTS ; device++) {
+		if (sn_pci_slot_valid(pci_bus, device) != 1)
+			continue;
+
+		bss_hotplug_slot = kzalloc(sizeof(*bss_hotplug_slot),
+					   GFP_KERNEL);
+		if (!bss_hotplug_slot) {
+			rc = -ENOMEM;
+			goto alloc_err;
+		}
+
+		bss_hotplug_slot->info =
+			kzalloc(sizeof(struct hotplug_slot_info),
+				GFP_KERNEL);
+		if (!bss_hotplug_slot->info) {
+			rc = -ENOMEM;
+			goto alloc_err;
+		}
+
+		if (sn_hp_slot_private_alloc(bss_hotplug_slot,
+					     pci_bus, device, name)) {
+			rc = -ENOMEM;
+			goto alloc_err;
+		}
+		bss_hotplug_slot->ops = &sn_hotplug_slot_ops;
+
+		rc = pci_hp_register(bss_hotplug_slot, pci_bus, device, name);
+		if (rc)
+			goto register_err;
+
+		pci_slot = bss_hotplug_slot->pci_slot;
+		rc = sysfs_create_file(&pci_slot->kobj,
+				       &sn_slot_path_attr.attr);
+		if (rc)
+			goto register_err;
+	}
+	pci_dbg(pci_bus->self, "Registered bus with hotplug\n");
+	return rc;
+
+register_err:
+	pci_dbg(pci_bus->self, "bus failed to register with err = %d\n",
+		rc);
+
+alloc_err:
+	if (rc == -ENOMEM)
+		pci_dbg(pci_bus->self, "Memory allocation error\n");
+
+	/* destroy THIS element */
+	if (bss_hotplug_slot)
+		sn_release_slot(bss_hotplug_slot);
+
+	/* destroy anything else on the list */
+	while ((bss_hotplug_slot = sn_hp_destroy())) {
+		pci_hp_deregister(bss_hotplug_slot);
+		sn_release_slot(bss_hotplug_slot);
+	}
+
+	return rc;
+}
+
+static int __init sn_pci_hotplug_init(void)
+{
+	struct pci_bus *pci_bus = NULL;
+	int rc;
+	int registered = 0;
+
+	if (!sn_prom_feature_available(PRF_HOTPLUG_SUPPORT)) {
+		printk(KERN_ERR "%s: PROM version does not support hotplug.\n",
+		       __func__);
+		return -EPERM;
+	}
+
+	INIT_LIST_HEAD(&sn_hp_list);
+
+	while ((pci_bus = pci_find_next_bus(pci_bus))) {
+		if (!pci_bus->sysdata)
+			continue;
+
+		rc = sn_pci_bus_valid(pci_bus);
+		if (rc != 1) {
+			pci_dbg(pci_bus->self, "not a valid hotplug bus\n");
+			continue;
+		}
+		pci_dbg(pci_bus->self, "valid hotplug bus\n");
+
+		rc = sn_hotplug_slot_register(pci_bus);
+		if (!rc) {
+			registered = 1;
+		} else {
+			registered = 0;
+			break;
+		}
+	}
+
+	return registered == 1 ? 0 : -ENODEV;
+}
+
+static void __exit sn_pci_hotplug_exit(void)
+{
+	struct hotplug_slot *bss_hotplug_slot;
+
+	while ((bss_hotplug_slot = sn_hp_destroy())) {
+		pci_hp_deregister(bss_hotplug_slot);
+		sn_release_slot(bss_hotplug_slot);
+	}
+
+	if (!list_empty(&sn_hp_list))
+		printk(KERN_ERR "%s: internal list is not empty\n", __FILE__);
+}
+
+module_init(sn_pci_hotplug_init);
+module_exit(sn_pci_hotplug_exit);