[RFC PATCH v2 14/16] ACPIHP: implement the state machine for ACPI hotplug slots

[Jiang Liu <jiang.liu@huawei.com>]

From: Jiang Liu <jiang.liu@huawei.com>

This patch implements the core of the new ACPI hotplug framework, it drivers
the state machine for ACPI hotplug slots according to user commands. It also
resolve dependencies among slots when transit the state machine.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
---
 drivers/acpi/hotplug/Makefile        |    1 +
 drivers/acpi/hotplug/acpihp_drv.h    |    9 +
 drivers/acpi/hotplug/state_machine.c |  633 ++++++++++++++++++++++++++++++++++
 3 files changed, 643 insertions(+)
 create mode 100644 drivers/acpi/hotplug/state_machine.c

diff --git a/drivers/acpi/hotplug/Makefile b/drivers/acpi/hotplug/Makefile
index 55d559a..9383320 100644
--- a/drivers/acpi/hotplug/Makefile
+++ b/drivers/acpi/hotplug/Makefile
@@ -14,3 +14,4 @@ acpihp_drv-y					= drv_main.o
 acpihp_drv-y					+= dependency.o
 acpihp_drv-y					+= cancel.o
 acpihp_drv-y					+= configure.o
+acpihp_drv-y					+= state_machine.o
diff --git a/drivers/acpi/hotplug/acpihp_drv.h b/drivers/acpi/hotplug/acpihp_drv.h
index eca2036..3b6dbdd 100644
--- a/drivers/acpi/hotplug/acpihp_drv.h
+++ b/drivers/acpi/hotplug/acpihp_drv.h
@@ -25,6 +25,9 @@
 #ifndef	__ACPIHP_DRV_H__
 #define	__ACPIHP_DRV_H__
 
+/* Timeout value to wait for firmware to power on the slot */
+#define ACPIHP_EVENT_WAIT_TIME  (100 * HZ)
+
 /* Commands to change state of a hotplug slot */
 enum acpihp_drv_cmd {
 	ACPIHP_DRV_CMD_NOOP = 0,
@@ -68,6 +71,9 @@ struct acpihp_slot_dependency {
 	u32				opcodes;
 };
 
+extern struct mutex state_machine_mutex;
+extern wait_queue_head_t acpihp_drv_event_wq;
+
 void acpihp_drv_get_data(struct acpihp_slot *slot,
 			 struct acpihp_slot_drv **data);
 int acpihp_drv_enumerate_devices(struct acpihp_slot *slot);
@@ -92,4 +98,7 @@ int acpihp_drv_cancel_wait(struct list_head *list);
 int acpihp_drv_configure(struct list_head *list);
 int acpihp_drv_unconfigure(struct list_head *list);
 
+/* The heart of the ACPI system device hotplug driver */
+int acpihp_drv_change_state(struct acpihp_slot *slot, enum acpihp_drv_cmd cmd);
+
 #endif	/* __ACPIHP_DRV_H__ */
diff --git a/drivers/acpi/hotplug/state_machine.c b/drivers/acpi/hotplug/state_machine.c
new file mode 100644
index 0000000..9f61804
--- /dev/null
+++ b/drivers/acpi/hotplug/state_machine.c
@@ -0,0 +1,633 @@
+/*
+ * Copyright (C) 2011 Huawei Tech. Co., Ltd.
+ * Copyright (C) 2011 Jiang Liu <jiang.liu@huawei.com>
+ * Copyright (C) 2011 Hanjun Guo <guohanjun@huawei.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/mutex.h>
+#include <linux/wait.h>
+#include <acpi/acpi_hotplug.h>
+#include "acpihp_drv.h"
+
+/*
+ * Global lock to serialize manipulating of dependency list among hotplug slots
+ * to avoid deadlock among slots. The lock order is:
+ * 1) acquire state_machine_mutex;
+ * 2) acquire drv_data->op_mutex;
+ * 3) acquire slot->slot_mutex;
+ */
+DEFINE_MUTEX(state_machine_mutex);
+
+DECLARE_WAIT_QUEUE_HEAD(acpihp_drv_event_wq);
+
+static int acpihp_drv_lock_slot(struct acpihp_slot *slot)
+{
+	int retval = 0;
+	struct acpihp_slot_drv *drv_data;
+
+	acpihp_drv_get_data(slot, &drv_data);
+	if (!mutex_trylock(&drv_data->op_mutex)) {
+		ACPIHP_DEBUG("slot %s is busy in state %d.\n",
+			     slot->name, slot->state);
+		retval = -EBUSY;
+	}
+
+	return retval;
+}
+
+static void acpihp_drv_unlock_slot(struct acpihp_slot *slot)
+{
+	struct acpihp_slot_drv *drv_data;
+
+	acpihp_drv_get_data(slot, &drv_data);
+	BUG_ON(!mutex_is_locked(&drv_data->op_mutex));
+	mutex_unlock(&drv_data->op_mutex);
+}
+
+/*
+ * Lock all slots in the dependency list to serialize concurrent operations.
+ * Caller must hold state_machine_mutex.
+ */
+static int acpihp_drv_lock_slots(struct list_head *list,
+				 struct acpihp_slot *slot)
+{
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node)
+		if (acpihp_drv_lock_slot(dep->slot))
+			goto unlock;
+
+	return 0;
+
+unlock:
+	list_for_each_entry_continue_reverse(dep, list, node)
+		acpihp_drv_unlock_slot(dep->slot);
+
+	return -EBUSY;
+}
+
+static void acpihp_drv_unlock_slots(struct list_head *list)
+{
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node)
+		acpihp_drv_unlock_slot(dep->slot);
+}
+
+static bool acpihp_drv_is_ancestor(struct acpihp_slot *ancestor,
+				   struct acpihp_slot *slot)
+{
+	while (slot) {
+		if (slot->parent == ancestor)
+			return true;
+		slot = slot->parent;
+	};
+
+	return false;
+}
+
+/*
+ * Check whether the command is valid according to current slot state,
+ * and get required operations for this slot if command is valid.
+ */
+static int acpihp_drv_validate_transition(struct acpihp_slot_dependency *dep,
+					  struct acpihp_slot *target,
+					  enum acpihp_drv_cmd cmd)
+{
+	u32 op1, op2;
+	struct acpihp_slot *slot = dep->slot;
+
+	if (slot->state <= ACPIHP_SLOT_STATE_UNKNOWN ||
+	    slot->state >= ACPIHP_SLOT_STATE_MAX) {
+		ACPIHP_DEBUG("invalid slot state %d.\n", slot->state);
+		return -EINVAL;
+	} else if (slot->state >= ACPIHP_SLOT_STATE_POWERING_ON) {
+		/*
+		 * This shouldn't happen, transcendant states are protected
+		 * by slot->op_mutex.
+		 */
+		BUG_ON(slot->state);
+		return -EBUSY;
+	}
+
+	op1 = op2 = ACPIHP_DRV_CMD_NOOP;
+	dep->opcodes = ACPIHP_DRV_CMD_NOOP;
+
+	/*
+	 * To be compatible with legacy OSes, the PCI host bridges built into
+	 * physical processor may be hosted directly under \\__SB instead of
+	 * under the CONTAINER device corresponding to physical processor.
+	 * That's really a corner case to deal with.
+	 */
+	switch (cmd) {
+	case ACPIHP_DRV_CMD_POWERON:
+		if (slot->state == ACPIHP_SLOT_STATE_ABSENT)
+			return -EINVAL;
+		else if (slot->state == ACPIHP_SLOT_STATE_PRESENT)
+			dep->opcodes = ACPIHP_DRV_CMD_POWERON;
+		break;
+
+	case ACPIHP_DRV_CMD_CONNECT:
+		/*
+		 * Its parent must have already been connected when connecting
+		 * a slot, otherwise the device tree topology becomes incorrect.
+		 */
+		if (target == slot || acpihp_drv_is_ancestor(slot, target))
+			op2 = ACPIHP_DRV_CMD_CONNECT;
+
+		if (slot->state == ACPIHP_SLOT_STATE_ABSENT)
+			return -EINVAL;
+		else if (slot->state == ACPIHP_SLOT_STATE_PRESENT)
+			dep->opcodes = ACPIHP_DRV_CMD_POWERON | op2;
+		else if (slot->state == ACPIHP_SLOT_STATE_POWERED)
+			dep->opcodes = op2;
+		break;
+
+	case ACPIHP_DRV_CMD_CONFIGURE:
+		/* Only CONFIGURE the requested slot */
+		if (slot == target)
+			op1 = ACPIHP_DRV_CMD_CONFIGURE;
+		/*
+		 * Its parent must have already been connected when configuring
+		 * a slot, otherwise the device tree topology becomes incorrect.
+		 */
+		if (target == slot || acpihp_drv_is_ancestor(slot, target))
+			op2 = ACPIHP_DRV_CMD_CONNECT;
+
+		if (slot->state == ACPIHP_SLOT_STATE_ABSENT)
+			return -EINVAL;
+		else if (slot->state == ACPIHP_SLOT_STATE_PRESENT)
+			dep->opcodes = ACPIHP_DRV_CMD_POWERON | op1 | op2;
+		else if (slot->state == ACPIHP_SLOT_STATE_POWERED)
+			dep->opcodes = op1 | op2;
+		else if (slot->state == ACPIHP_SLOT_STATE_CONNECTED)
+			dep->opcodes = op1;
+		break;
+
+	case ACPIHP_DRV_CMD_UNCONFIGURE:
+		/* Only UNCONFIGURE the requested slot */
+		if (slot->state == ACPIHP_SLOT_STATE_CONFIGURED &&
+		    slot == target)
+			dep->opcodes = ACPIHP_DRV_CMD_UNCONFIGURE;
+		break;
+
+	case ACPIHP_DRV_CMD_DISCONNECT:
+		/*
+		 * all descedant slots must be unconfigured/disconnected
+		 * when disconnecting a slot.
+		 */
+		if (target == slot || acpihp_drv_is_ancestor(target, slot)) {
+			op1 = ACPIHP_DRV_CMD_UNCONFIGURE;
+			op2 = ACPIHP_DRV_CMD_DISCONNECT;
+		}
+
+		if (slot->state == ACPIHP_SLOT_STATE_CONFIGURED)
+			dep->opcodes = op1 | op2;
+		else if (slot->state == ACPIHP_SLOT_STATE_CONNECTED)
+			dep->opcodes = op2;
+		break;
+
+	case ACPIHP_DRV_CMD_POWEROFF:
+		/*
+		 * All slots have dependency on the target slot must be
+		 * powered off when powering the target slot off.
+		 */
+		if (slot->state == ACPIHP_SLOT_STATE_CONFIGURED)
+			dep->opcodes = ACPIHP_DRV_CMD_UNCONFIGURE |
+				       ACPIHP_DRV_CMD_DISCONNECT |
+				       ACPIHP_DRV_CMD_POWEROFF;
+		else if (slot->state == ACPIHP_SLOT_STATE_CONNECTED)
+			dep->opcodes = ACPIHP_DRV_CMD_DISCONNECT |
+				       ACPIHP_DRV_CMD_POWEROFF;
+		else if (slot->state == ACPIHP_SLOT_STATE_POWERED)
+			dep->opcodes = ACPIHP_DRV_CMD_POWEROFF;
+		break;
+
+	default:
+		ACPIHP_DEBUG("invalid command %d.\n", cmd);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int acpihp_drv_validate_command(struct list_head *list,
+		struct acpihp_slot *target, enum acpihp_drv_cmd cmd)
+{
+	int retval;
+	struct acpihp_slot *slot;
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node) {
+		slot = dep->slot;
+		acpihp_drv_update_slot_status(slot);
+
+		retval = acpihp_drv_validate_transition(dep, target, cmd);
+		if (retval) {
+			ACPIHP_DEBUG("Invalid cmd for slot %s in state %d.\n",
+				     slot->name, slot->state);
+			return retval;
+		}
+
+		/*
+		 * Check whether the slot is in good shape if we need to
+		 * operate on it.
+		 */
+		if (dep->opcodes &&
+		    acpihp_slot_get_flag(slot, ACPIHP_SLOT_FLAG_FAULT)) {
+			ACPIHP_WARN("slot %s has been marked as faulty.\n",
+				     slot->name);
+			return -ENXIO;
+		} else if ((dep->opcodes & ACPIHP_DRV_CMD_UNCONFIGURE) &&
+		    acpihp_slot_get_flag(slot, ACPIHP_SLOT_FLAG_IRREMOVABLE)) {
+			ACPIHP_WARN("slot %s is busy.\n", slot->name);
+			return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+static int acpihp_drv_pre_execute(struct acpihp_slot *slot,
+				  enum acpihp_drv_cmd cmd,
+				  struct list_head **head)
+{
+	int retval;
+	struct list_head *list;
+	struct acpihp_slot_drv *drv_data;
+
+	mutex_lock(&state_machine_mutex);
+
+	acpihp_drv_get_data(slot, &drv_data);
+	*head = list = &drv_data->depend_list;
+
+	if (cmd == ACPIHP_DRV_CMD_CANCEL) {
+		/*
+		 * Set cancellation flags on all affected slots.
+		 * All affected slots should already be on drv_data->depend_list
+		 * if there's inprogress operation for the slot.
+		 *
+		 * state_machine_mutex must be held to serialize calls to
+		 *	acpihp_drv_cancel_init(),
+		 *	acpihp_drv_cancel_start(),
+		 *	acpihp_drv_cancel_fini(),
+		 */
+		retval = acpihp_drv_cancel_start(&drv_data->depend_list);
+		goto out;
+	}
+
+	if (mutex_is_locked(&drv_data->op_mutex)) {
+		ACPIHP_DEBUG("slot %s is busy.\n", slot->name);
+		retval = -EBUSY;
+		goto out;
+	}
+
+	INIT_LIST_HEAD(list);
+	retval = acpihp_drv_generate_dependency_list(slot, list, cmd);
+	if (retval) {
+		ACPIHP_DEBUG("fails to get dependency list for slot %s.\n",
+			     slot->name);
+		goto out;
+	}
+
+	retval = acpihp_drv_lock_slots(list, slot);
+	if (retval) {
+		acpihp_drv_destroy_dependency_list(list);
+		goto out;
+	}
+
+	retval = acpihp_drv_validate_command(list, slot, cmd);
+	if (retval) {
+		acpihp_drv_unlock_slots(list);
+		acpihp_drv_destroy_dependency_list(list);
+		goto out;
+	}
+
+	acpihp_drv_cancel_init(list);
+
+out:
+	mutex_unlock(&state_machine_mutex);
+
+	return retval;
+}
+
+static void acpihp_drv_post_execute(struct list_head *list,
+				    enum acpihp_drv_cmd cmd)
+{
+	if (cmd == ACPIHP_DRV_CMD_CANCEL)
+		return;
+
+	mutex_lock(&state_machine_mutex);
+	if (list && !list_empty(list)) {
+		acpihp_drv_cancel_fini(list);
+		acpihp_drv_unlock_slots(list);
+		acpihp_drv_destroy_dependency_list(list);
+	}
+	mutex_unlock(&state_machine_mutex);
+}
+
+static int acpihp_drv_poweron_slot(struct acpihp_slot *slot)
+{
+	acpi_status status;
+	struct acpihp_slot_drv *drv_data;
+
+	if (acpihp_slot_powered(slot))
+		return 0;
+
+	acpihp_drv_get_data(slot, &drv_data);
+	drv_data->event_flag = ACPIHP_DRV_EVENT_FROM_OS;
+
+	status = acpihp_slot_poweron(slot);
+	if (ACPI_FAILURE(status)) {
+		ACPIHP_WARN("fails to power on slot %s.\n", slot->name);
+		if (status == AE_SUPPORT)
+			return -ENOSYS;
+		else
+			return -ENXIO;
+	}
+
+	wait_event_timeout(acpihp_drv_event_wq, acpihp_slot_powered(slot),
+			   ACPIHP_EVENT_WAIT_TIME);
+	if (!acpihp_slot_powered(slot)) {
+		ACPIHP_WARN("fails to power on slot %s.\n", slot->name);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int acpihp_drv_poweron(struct list_head *list)
+{
+	int retval = 0;
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node) {
+		if (!(dep->opcodes & ACPIHP_DRV_CMD_POWERON))
+			continue;
+
+		acpihp_slot_change_state(dep->slot,
+					 ACPIHP_SLOT_STATE_POWERING_ON);
+		retval = acpihp_drv_poweron_slot(dep->slot);
+		if (!retval) {
+			ACPIHP_DEBUG("succeed to power on slot %s!\n",
+				     dep->slot->name);
+			acpihp_slot_change_state(dep->slot,
+						 ACPIHP_SLOT_STATE_POWERED);
+		} else {
+			acpihp_slot_change_state(dep->slot,
+						 ACPIHP_SLOT_STATE_PRESENT);
+			if (retval != -ENOSYS)
+				acpihp_slot_set_flag(dep->slot,
+						     ACPIHP_SLOT_FLAG_FAULT);
+			break;
+		}
+	}
+
+	return retval;
+}
+
+static int acpihp_drv_poweroff_slot(struct acpihp_slot *slot)
+{
+	acpi_status status;
+
+	if (acpihp_slot_powered(slot))
+		return 0;
+
+	status = acpihp_slot_poweroff(slot);
+	if (ACPI_FAILURE(status)) {
+		ACPIHP_WARN("fails to power off slot %s.\n", slot->name);
+		if (status == AE_SUPPORT)
+			return -ENOSYS;
+		else
+			return -ENXIO;
+	}
+
+	if (acpihp_slot_powered(slot)) {
+		ACPIHP_WARN("fails to power off slot %s.\n", slot->name);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int acpihp_drv_poweroff(struct list_head *list)
+{
+	int retval = 0;
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node) {
+		if (!(dep->opcodes & ACPIHP_DRV_CMD_POWEROFF))
+			continue;
+
+		acpihp_slot_change_state(dep->slot,
+					 ACPIHP_SLOT_STATE_POWERING_OFF);
+		retval = acpihp_drv_poweroff_slot(dep->slot);
+		if (!retval) {
+			ACPIHP_DEBUG("succeed to power off slot %s!\n",
+				     dep->slot->name);
+			acpihp_slot_change_state(dep->slot,
+						 ACPIHP_SLOT_STATE_PRESENT);
+		} else {
+			acpihp_slot_change_state(dep->slot,
+						 ACPIHP_SLOT_STATE_POWERED);
+			if (retval != -ENOSYS)
+				acpihp_slot_set_flag(dep->slot,
+						     ACPIHP_SLOT_FLAG_FAULT);
+			break;
+		}
+	}
+
+	return retval;
+}
+
+static int acpihp_drv_connect_slot(struct acpihp_slot *slot)
+{
+	int retval;
+
+	retval = acpihp_add_devices(slot->handle, NULL);
+	if (retval)
+		ACPIHP_DEBUG("fails to add ACPI devices for slot %s.\n",
+			     slot->name);
+	else {
+		retval = acpihp_drv_enumerate_devices(slot);
+		if (retval)
+			ACPIHP_DEBUG("fails to enumerate device for slot %s.\n",
+				     slot->name);
+	}
+
+	return retval;
+}
+
+static int acpihp_drv_connect(struct list_head *list)
+{
+	int retval = 0;
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node) {
+		if (!(dep->opcodes & ACPIHP_DRV_CMD_CONNECT))
+			continue;
+
+		acpihp_slot_change_state(dep->slot,
+					 ACPIHP_SLOT_STATE_CONNECTING);
+		retval = acpihp_drv_connect_slot(dep->slot);
+		if (!retval) {
+			ACPIHP_DEBUG("succeed to connect slot %s!\n",
+				     dep->slot->name);
+			acpihp_slot_change_state(dep->slot,
+						 ACPIHP_SLOT_STATE_CONNECTED);
+		} else {
+			acpihp_drv_update_slot_state(dep->slot);
+			break;
+		}
+	}
+
+	return retval;
+}
+
+static int acpihp_drv_disconnect_slot(struct acpihp_slot *slot)
+{
+	int retval = 0;
+	enum acpihp_dev_type i;
+	struct acpi_device *device = NULL;
+
+	/* remove all devices connecting to slot */
+	for (i = ACPIHP_DEV_TYPE_UNKNOWN; i < ACPIHP_DEV_TYPE_MAX; i++) {
+		retval = acpihp_remove_device_list(&slot->dev_lists[i]);
+		if (retval) {
+			ACPIHP_DEBUG("fails to remove devices under slot %s.\n",
+				     slot->name);
+			return retval;
+		}
+	}
+
+	/* remove ACPI devices */
+	retval = acpi_bus_get_device(slot->handle, &device);
+	if (!retval && device) {
+		retval = acpi_bus_trim(device, 1);
+		if (retval)
+			ACPIHP_WARN("fails to remove ACPI devices for %s.\n",
+				    slot->name);
+	} else {
+		ACPIHP_WARN("fails to get ACPI device for slot %s.\n",
+			    slot->name);
+	}
+
+	return retval;
+}
+
+static int acpihp_drv_disconnect(struct list_head *list)
+{
+	int retval = 0;
+	struct acpihp_slot_dependency *dep;
+
+	list_for_each_entry(dep, list, node) {
+		if (!(dep->opcodes & ACPIHP_DRV_CMD_DISCONNECT))
+			continue;
+
+		acpihp_slot_change_state(dep->slot,
+					 ACPIHP_SLOT_STATE_DISCONNECTING);
+		retval = acpihp_drv_disconnect_slot(dep->slot);
+		if (!retval) {
+			ACPIHP_DEBUG("succeed to disconnect slot %s!\n",
+				     dep->slot->name);
+			acpihp_slot_change_state(dep->slot,
+						 ACPIHP_SLOT_STATE_POWERED);
+		} else {
+			acpihp_drv_update_slot_state(dep->slot);
+			break;
+		}
+	}
+
+	return retval;
+}
+
+static int acpihp_drv_execute(struct list_head *list, enum acpihp_drv_cmd cmd)
+{
+	int retval = 0;
+	bool connect = false, configure = false;
+	bool disconnect = false, poweroff = false;
+
+	if (!list || list_empty(list)) {
+		ACPIHP_DEBUG("slot dependency list is NULL or empty!\n");
+		retval = -EINVAL;
+		goto out;
+	}
+
+	switch (cmd) {
+	case ACPIHP_DRV_CMD_CONFIGURE:
+		configure = true;
+		/* fall through */
+	case ACPIHP_DRV_CMD_CONNECT:
+		connect = true;
+		/* fall through */
+	case ACPIHP_DRV_CMD_POWERON:
+		retval = acpihp_drv_poweron(list);
+		if (!retval && connect)
+			retval = acpihp_drv_connect(list);
+		if (!retval && configure)
+			retval = acpihp_drv_configure(list);
+		break;
+
+	case ACPIHP_DRV_CMD_POWEROFF:
+		poweroff = true;
+		/* fall through */
+	case ACPIHP_DRV_CMD_DISCONNECT:
+		disconnect = true;
+		/* fall through */
+	case ACPIHP_DRV_CMD_UNCONFIGURE:
+		retval = acpihp_drv_unconfigure(list);
+		if (!retval && disconnect)
+			retval = acpihp_drv_disconnect(list);
+		if (!retval && poweroff)
+			retval = acpihp_drv_poweroff(list);
+		break;
+
+	case ACPIHP_DRV_CMD_CANCEL:
+		retval = acpihp_drv_cancel_wait(list);
+		break;
+
+	default:
+		ACPIHP_DEBUG("unsupported command %d.\n", cmd);
+		retval = -EINVAL;
+		break;
+	}
+
+out:
+	return retval;
+}
+
+/*
+ * The heart of ACPI based system device hotplug driver, which drivers the
+ * slot state machine according to commands.
+ */
+int acpihp_drv_change_state(struct acpihp_slot *slot, enum acpihp_drv_cmd cmd)
+{
+	int retval;
+	struct list_head *list = NULL;
+
+	retval = acpihp_drv_pre_execute(slot, cmd, &list);
+	if (!retval) {
+		retval = acpihp_drv_execute(list, cmd);
+		acpihp_drv_post_execute(list, cmd);
+	}
+
+	return retval;
+}
-- 
1.7.9.5