[RFC PATCH v2 01/16] ACPIHP: introduce a framework for ACPI based system device hotplug

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

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

Modern high-end server may support advanced hotplug features for system
devices, including physical processor, memory board, IO extension board/box
and/or computer node. The ACPI specifications have provided standard
interfaces between firmware and OS to support device hotplug at runtime.
This patch series provide an ACPI based hotplug framework to support system
device hotplug at runtime, which will replace current existing ACPI device
driver based CPU/memory/CONTAINER hotplug mechanism.

An ACPI hotplug slot is an abstraction of receptacles, where a group of
system devices could be connected to. Every ACPI system device hotplug slot
will be associated with a device class named acpihp_slot_class. This device
class provides sysfs interfaces for each slot:
linux-drf:/sys/devices/LNXSYSTM:00/acpihp/NODE00 # ll
-r--r--r-- 1 root root 65536 Jul 28 16:01 capabilities
-r--r--r-- 1 root root 65536 Jul 28 16:01 object
-r--r--r-- 1 root root 65536 Jul 28 16:01 state
-r--r--r-- 1 root root 65536 Jul 28 16:01 status
-r--r--r-- 1 root root 65536 Jul 28 16:01 type

This patch also implements some utility functions to support ACPI hotplug
slot enumerator and ACPI hotplug driver.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Gaohuai Han <hangaohuai@huawei.com>
---
 drivers/acpi/Kconfig          |   12 +
 drivers/acpi/Makefile         |    2 +
 drivers/acpi/hotplug/Makefile |    6 +
 drivers/acpi/hotplug/core.c   |  593 +++++++++++++++++++++++++++++++++++++++++
 include/acpi/acpi_hotplug.h   |  191 +++++++++++++
 5 files changed, 804 insertions(+)
 create mode 100644 drivers/acpi/hotplug/Makefile
 create mode 100644 drivers/acpi/hotplug/core.c
 create mode 100644 include/acpi/acpi_hotplug.h

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 8099895..e457d31 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -321,6 +321,18 @@ config X86_PM_TIMER
 	  You should nearly always say Y here because many modern
 	  systems require this timer. 
 
+menuconfig ACPI_HOTPLUG
+	bool "ACPI Based System Device Hotplug (EXPERIMENTAL)"
+	depends on (X86 || IA64) && SYSFS && EXPERIMENTAL
+	default n
+	help
+	  This option enables an framework for ACPI based system devices
+	  hotplug, including physical processor, memory device, IO host
+	  bridge and/or computer node etc.
+
+	  If your hardware and firmware do not support adding or removing
+	  of system devices at runtime, you need not to enable this option.
+
 config ACPI_CONTAINER
 	tristate "Container and Module Devices (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 47199e2..17bea6c 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -73,3 +73,5 @@ obj-$(CONFIG_ACPI_PROCESSOR_AGGREGATOR) += acpi_pad.o
 obj-$(CONFIG_ACPI_IPMI)		+= acpi_ipmi.o
 
 obj-$(CONFIG_ACPI_APEI)		+= apei/
+
+obj-$(CONFIG_ACPI_HOTPLUG)	+= hotplug/
diff --git a/drivers/acpi/hotplug/Makefile b/drivers/acpi/hotplug/Makefile
new file mode 100644
index 0000000..5e7790f
--- /dev/null
+++ b/drivers/acpi/hotplug/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for ACPI based system device hotplug drivers
+#
+
+obj-$(CONFIG_ACPI_HOTPLUG)			+= acpihp.o
+acpihp-y					= core.o
diff --git a/drivers/acpi/hotplug/core.c b/drivers/acpi/hotplug/core.c
new file mode 100644
index 0000000..6fac499
--- /dev/null
+++ b/drivers/acpi/hotplug/core.c
@@ -0,0 +1,593 @@
+/*
+ * Copyright (C) 2011 Huawei Tech. Co., Ltd.
+ * Copyright (C) 2011 Jiang Liu <jiang.liu@huawei.com>
+ * Copyright (C) 2011 Gaohuai Han <hangaohuai@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/types.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <linux/bug.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/sem.h>
+#include <linux/version.h>
+#include <acpi/acpi.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_hotplug.h>
+
+#define to_acpihp_slot(d) container_of(d, struct acpihp_slot, dev)
+
+extern struct acpi_device *acpi_root;
+
+static DEFINE_MUTEX(acpihp_mutex);
+static int acpihp_class_count;
+static struct kset *acpihp_slot_kset;
+
+static char *acpihp_slot_names[ACPIHP_SLOT_TYPE_MAX] = {
+	[ACPIHP_SLOT_TYPE_UNKNOWN]	= "UNKNOWN",
+	[ACPIHP_SLOT_TYPE_COMMON]	= "SLOT",
+	[ACPIHP_SLOT_TYPE_NODE]		= "NODE",
+	[ACPIHP_SLOT_TYPE_SYSTEM_BOARD]	= "SB",
+	[ACPIHP_SLOT_TYPE_CPU]		= "CPU",
+	[ACPIHP_SLOT_TYPE_MEM]		= "MEM",
+	[ACPIHP_SLOT_TYPE_IOX]		= "IOX",
+};
+
+static char *acpihp_slot_descriptions[ACPIHP_SLOT_TYPE_MAX] = {
+	[ACPIHP_SLOT_TYPE_UNKNOWN]	= "unknown slot",
+	[ACPIHP_SLOT_TYPE_COMMON]	= "common slot",
+	[ACPIHP_SLOT_TYPE_NODE]		= "computer node slot",
+	[ACPIHP_SLOT_TYPE_SYSTEM_BOARD]	= "system board slot",
+	[ACPIHP_SLOT_TYPE_CPU]		= "processor slot",
+	[ACPIHP_SLOT_TYPE_MEM]		= "memory slot",
+	[ACPIHP_SLOT_TYPE_IOX]		= "IO extension slot",
+};
+
+static char *acpihp_slot_states[] = {
+	[ACPIHP_SLOT_STATE_UNKNOWN]		= "unknown",
+	[ACPIHP_SLOT_STATE_ABSENT]		= "absent",
+	[ACPIHP_SLOT_STATE_PRESENT]		= "present",
+	[ACPIHP_SLOT_STATE_POWERED]		= "powered",
+	[ACPIHP_SLOT_STATE_CONNECTED]		= "connected",
+	[ACPIHP_SLOT_STATE_CONFIGURED]		= "configured",
+	[ACPIHP_SLOT_STATE_POWERING_ON]		= "powering on",
+	[ACPIHP_SLOT_STATE_POWERING_OFF]	= "powering off",
+	[ACPIHP_SLOT_STATE_CONNECTING]		= "connecting",
+	[ACPIHP_SLOT_STATE_DISCONNECTING]	= "disconneting",
+	[ACPIHP_SLOT_STATE_CONFIGURING]		= "configuring",
+	[ACPIHP_SLOT_STATE_UNCONFIGURING]	= "unconfiguring",
+};
+
+static char *acpihp_slot_status[] = {
+	"ok",
+	"irremovable",
+	"fault",
+	"irremovable, fault",
+};
+
+static char *acpihp_dev_container_ids[] = {
+	"ACPI0004",
+	"PNP0A05",
+	"PNP0A06",
+	NULL
+};
+
+static char *acpihp_dev_cpu_ids[] = {
+	"ACPI0007",
+	"LNXCPU",
+	NULL
+};
+
+static char *acpihp_dev_mem_ids[] = {
+	"PNP0C80",
+	NULL
+};
+
+static char *acpihp_dev_pcihb_ids[] = {
+	"PNP0A03",
+	"PNP0A08",
+	NULL
+};
+
+static char *acpihp_dev_ioapic_ids[] = {
+	"ACPI0009",
+	"ACPI000A",
+	"ACPI000B",
+	NULL
+};
+
+static void acpihp_slot_release(struct device *dev)
+{
+	struct acpihp_slot *slot = to_acpihp_slot(dev);
+
+	if (!list_empty(&slot->slot_list))
+		ACPIHP_ERROR("slot->slot_list is not empty.\n");
+
+	if (!list_empty(&slot->drvdata_list))
+		ACPIHP_ERROR("slot->drvdata_list is not empty.\n");
+
+	if (!list_empty(&slot->slot_id_list))
+		ACPIHP_ERROR("slot->slot_id_list is not empty.\n");
+
+	kfree(slot->full_path);
+	kfree(slot);
+}
+
+struct acpihp_slot *acpihp_create_slot(acpi_handle handle, char *name)
+{
+	struct acpihp_slot *slot;
+
+	if (name == NULL) {
+		ACPIHP_DEBUG("slot name is NULL.\n");
+		return NULL;
+	} else if (strlen(name) >= ACPIHP_SLOT_NAME_MAX_SIZE) {
+		ACPIHP_WARN("slot name %s is too big.\n", name);
+		return NULL;
+	}
+
+	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
+	if (slot == NULL) {
+		ACPIHP_DEBUG("failed to allocate slot dev.\n");
+		return NULL;
+	}
+
+	slot->handle = handle;
+	INIT_LIST_HEAD(&slot->slot_list);
+	INIT_LIST_HEAD(&slot->drvdata_list);
+	INIT_LIST_HEAD(&slot->slot_id_list);
+	strncpy(slot->name, name, sizeof(slot->name) - 1);
+	mutex_init(&slot->slot_mutex);
+
+	slot->dev.class = &acpihp_slot_class;
+	device_initialize(&slot->dev);
+
+	return slot;
+}
+EXPORT_SYMBOL_GPL(acpihp_create_slot);
+
+static size_t acpihp_generate_link_name(struct acpihp_slot *slot,
+					char *name, size_t off)
+{
+	if (slot->parent)
+		off = acpihp_generate_link_name(slot->parent, name, off);
+	off += snprintf(name + off, PAGE_SIZE - off, "%s.", slot->name);
+	BUG_ON(off >= PAGE_SIZE);
+
+	return off;
+}
+
+int acpihp_register_slot(struct acpihp_slot *slot)
+{
+	int ret;
+	char *name;
+	size_t off;
+
+	if (!slot || !slot->slot_ops)
+		return -EINVAL;
+
+	/* Hook top level hotplug slots under ACPI root device */
+	if (slot->parent)
+		slot->dev.parent = &slot->parent->dev;
+	else
+		slot->dev.parent = &acpi_root->dev;
+
+	ret = device_add(&slot->dev);
+	if (!ret) {
+		slot->flags |= ACPIHP_SLOT_FLAG_REGISTERED;
+		name = kmalloc(PAGE_SIZE, GFP_KERNEL);
+		if (name) {
+			off = acpihp_generate_link_name(slot, name, 0);
+			name[off - 1] = '\0';
+			slot->full_path = kstrdup(name, GFP_KERNEL);
+			if (slot->full_path)
+				kfree(name);
+			else
+				slot->full_path = name;
+
+			/* Fails to create symlink is non-fatal */
+			if (sysfs_create_link(&acpihp_slot_kset->kobj,
+					  &slot->dev.kobj, slot->full_path))
+				ACPIHP_WARN("fails to create link for %s.\n",
+					    slot->name);
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(acpihp_register_slot);
+
+void acpihp_unregister_slot(struct acpihp_slot *slot)
+{
+	if (slot && (slot->flags & ACPIHP_SLOT_FLAG_REGISTERED)) {
+		sysfs_remove_link(&acpihp_slot_kset->kobj, slot->full_path);
+		device_del(&slot->dev);
+	}
+}
+EXPORT_SYMBOL_GPL(acpihp_unregister_slot);
+
+struct acpihp_slot *acpihp_slot_get(struct acpihp_slot *slot)
+{
+	if (slot)
+		get_device(&slot->dev);
+
+	return slot;
+}
+EXPORT_SYMBOL_GPL(acpihp_slot_get);
+
+void acpihp_slot_put(struct acpihp_slot *slot)
+{
+	if (slot)
+		put_device(&slot->dev);
+}
+EXPORT_SYMBOL_GPL(acpihp_slot_put);
+
+static void acpihp_slot_data_handler(acpi_handle handle, void *context)
+{
+	return;
+}
+
+acpi_status acpihp_mark_slot(acpi_handle handle, struct acpihp_slot *slot)
+{
+	acpi_status status;
+
+	mutex_lock(&acpihp_mutex);
+	status = acpi_attach_data(handle, &acpihp_slot_data_handler, slot);
+	mutex_unlock(&acpihp_mutex);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(acpihp_mark_slot);
+
+acpi_status acpihp_unmark_slot(acpi_handle handle)
+{
+	acpi_status result;
+
+	mutex_lock(&acpihp_mutex);
+	result = acpi_detach_data(handle, &acpihp_slot_data_handler);
+	if (result == AE_NOT_FOUND)
+		result = AE_OK;
+	BUG_ON(result != AE_OK);
+	mutex_unlock(&acpihp_mutex);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(acpihp_unmark_slot);
+
+bool acpihp_check_slot(acpi_handle handle)
+{
+	acpi_status result;
+	void *data = NULL;
+
+	result = acpi_get_data(handle, &acpihp_slot_data_handler, &data);
+	BUG_ON(result != AE_OK && result != AE_NOT_FOUND);
+
+	return (result == AE_OK);
+}
+EXPORT_SYMBOL_GPL(acpihp_check_slot);
+
+bool acpihp_get_slot(acpi_handle handle, struct acpihp_slot **slot)
+{
+	acpi_status result;
+	void *data = NULL;
+
+	mutex_lock(&acpihp_mutex);
+	result = acpi_get_data(handle, &acpihp_slot_data_handler, &data);
+	if (slot) {
+		if (result == AE_OK) {
+			*slot = data;
+			acpihp_slot_get(*slot);
+		} else
+			*slot = NULL;
+	}
+	mutex_unlock(&acpihp_mutex);
+
+	return (result == AE_OK);
+}
+EXPORT_SYMBOL_GPL(acpihp_get_slot);
+
+bool acpihp_dev_match_ids(struct acpi_device_info *infop, char **ids)
+{
+	int i, j;
+	struct acpica_device_id_list *cid_list;
+
+	if (infop == NULL || ids == NULL) {
+		ACPIHP_DEBUG("invalid parameters.\n");
+		return false;
+	}
+
+	if (infop->valid & ACPI_VALID_HID) {
+		for (i = 0; ids[i]; i++) {
+			if (strncmp(ids[i], infop->hardware_id.string,
+				    infop->hardware_id.length) == 0) {
+				return true;
+			}
+		}
+	}
+
+	if (!(infop->valid & ACPI_VALID_CID)) {
+		for (i = 0; ids[i]; i++) {
+			cid_list = &infop->compatible_id_list;
+			for (j = 0; j < cid_list->count; j++) {
+				if (strncmp(ids[i],
+					    cid_list->ids[j].string,
+					    cid_list->ids[j].length) == 0) {
+						return true;
+				}
+			}
+		}
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(acpihp_dev_match_ids);
+
+int acpihp_dev_get_type(acpi_handle handle, enum acpihp_dev_type *type)
+{
+	struct acpi_device_info *infop = NULL;
+
+	if (handle == NULL || type == NULL) {
+		ACPIHP_DEBUG("invalid parameters.\n");
+		return -EINVAL;
+	}
+	if (ACPI_FAILURE(acpi_get_object_info(handle, &infop)))
+		return -ENODEV;
+
+	*type = ACPIHP_DEV_TYPE_UNKNOWN;
+	if (infop->type == ACPI_TYPE_PROCESSOR) {
+		*type = ACPIHP_DEV_TYPE_CPU;
+	} else if (infop->type == ACPI_TYPE_DEVICE) {
+		if (acpihp_dev_match_ids(infop, acpihp_dev_container_ids))
+			*type = ACPIHP_DEV_TYPE_CONTAINER;
+		else if (acpihp_dev_match_ids(infop, acpihp_dev_cpu_ids))
+			*type = ACPIHP_DEV_TYPE_CPU;
+		else if (acpihp_dev_match_ids(infop, acpihp_dev_mem_ids))
+			*type = ACPIHP_DEV_TYPE_MEM;
+		else if (acpihp_dev_match_ids(infop, acpihp_dev_pcihb_ids))
+			*type = ACPIHP_DEV_TYPE_HOST_BRIDGE;
+		else if (acpihp_dev_match_ids(infop, acpihp_dev_ioapic_ids))
+			*type = ACPIHP_DEV_TYPE_IOAPIC;
+		else if ((infop->valid & (ACPI_VALID_ADR | ACPI_VALID_HID |
+			 ACPI_VALID_CID)) == ACPI_VALID_ADR)
+			*type = ACPIHP_DEV_TYPE_MAX;
+	}
+	kfree(infop);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpihp_dev_get_type);
+
+char *acpihp_get_slot_type_name(enum acpihp_slot_type type)
+{
+	if (type < 0 || type >= ACPIHP_SLOT_TYPE_MAX) {
+		ACPIHP_DEBUG("invalid parameters.\n");
+		return "UNKNOWN";
+	} else {
+		return acpihp_slot_names[type];
+	}
+}
+EXPORT_SYMBOL_GPL(acpihp_get_slot_type_name);
+
+/*
+ * slot_ops should be valid during the life cycle of a slot, so no protection.
+ */
+acpi_status
+acpihp_slot_get_capabilities(struct acpihp_slot *slot, u32 *capability)
+{
+	if (slot == NULL || capability == NULL) {
+		ACPIHP_DEBUG("invalid parameters.\n");
+		return AE_BAD_PARAMETER;
+	} else if (slot->slot_ops == NULL ||
+		 slot->slot_ops->get_capabilities == NULL) {
+		ACPIHP_DEBUG("operation not supported.\n");
+		return AE_SUPPORT;
+	}
+
+	return slot->slot_ops->get_capabilities(slot->handle, capability);
+}
+EXPORT_SYMBOL_GPL(acpihp_slot_get_capabilities);
+
+acpi_status acpihp_slot_poweron(struct acpihp_slot *slot)
+{
+	if (slot == NULL) {
+		ACPIHP_DEBUG("invalid parameter.\n");
+		return AE_BAD_PARAMETER;
+	} else if (slot->slot_ops == NULL || slot->slot_ops->poweron == NULL) {
+		ACPIHP_DEBUG("operation not supported.\n");
+		return AE_SUPPORT;
+	}
+
+	return slot->slot_ops->poweron(slot->handle);
+}
+EXPORT_SYMBOL_GPL(acpihp_slot_poweron);
+
+acpi_status acpihp_slot_poweroff(struct acpihp_slot *slot)
+{
+	if (slot == NULL) {
+		ACPIHP_DEBUG("invalid parameter.\n");
+		return AE_BAD_PARAMETER;
+	} else if (slot->slot_ops == NULL || slot->slot_ops->poweroff == NULL) {
+		ACPIHP_DEBUG("operation not supported.\n");
+		return AE_SUPPORT;
+	}
+
+	return slot->slot_ops->poweroff(slot->handle);
+}
+EXPORT_SYMBOL_GPL(acpihp_slot_poweroff);
+
+/* SYSFS interfaces */
+static ssize_t acpihp_slot_object_show(struct device *d,
+		struct device_attribute *attr, char *buf)
+{
+	ssize_t sz;
+	struct acpihp_slot *slot = to_acpihp_slot(d);
+	struct acpi_buffer path = {ACPI_ALLOCATE_BUFFER, NULL};
+
+	sz = acpi_get_name(slot->handle, ACPI_FULL_PATHNAME, &path);
+	if (sz)
+		goto end;
+
+	sz = sprintf(buf, "%s\n", (char*)path.pointer);
+	kfree(path.pointer);
+end:
+	return sz;
+}
+
+static ssize_t acpihp_slot_type_show(struct device *d,
+		struct device_attribute *attr, char *buf)
+{
+	enum acpihp_slot_type type;
+	struct acpihp_slot *slot = to_acpihp_slot(d);
+
+	type = slot->type < 0 || slot->type >= ACPIHP_SLOT_TYPE_MAX ?
+		ACPIHP_SLOT_TYPE_UNKNOWN : slot->type;
+
+	return snprintf(buf, PAGE_SIZE, "%s: %s\n",
+			acpihp_get_slot_type_name(type),
+			acpihp_slot_descriptions[type]);
+}
+
+static ssize_t acpihp_slot_state_show(struct device *d,
+		struct device_attribute *attr, char *buf)
+{
+	enum acpihp_slot_state state;
+	acpi_status status;
+	unsigned long long sta;
+	struct acpihp_slot *slot = to_acpihp_slot(d);
+
+	state = slot->state < 0 || slot->state >= ACPIHP_SLOT_STATE_MAX ?
+		ACPIHP_SLOT_STATE_UNKNOWN : slot->state;
+
+	if ((ACPIHP_SLOT_STATE_ABSENT == state) ||
+	     (ACPIHP_SLOT_STATE_PRESENT == state)) {
+		status = acpi_evaluate_integer(slot->handle, "_STA", NULL,
+					       &sta);
+		if (ACPI_SUCCESS(status)) {
+			if ((sta & ACPI_STA_DEVICE_PRESENT) ==
+				ACPI_STA_DEVICE_PRESENT)
+				state = ACPIHP_SLOT_STATE_PRESENT;
+			else
+				state = ACPIHP_SLOT_STATE_ABSENT;
+		}
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", acpihp_slot_states[state]);
+}
+
+static ssize_t acpihp_slot_status_show(struct device *d,
+		struct device_attribute *attr, char *buf)
+{
+	struct acpihp_slot *slot = to_acpihp_slot(d);
+	u32 status = slot->flags & ACPIHP_SLOT_STATUS_MASK;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", acpihp_slot_status[status]);
+}
+
+static ssize_t acpihp_slot_capabilities_show(struct device *d,
+		struct device_attribute *attr, char *buf)
+{
+	ssize_t sz;
+	struct acpihp_slot *slot = to_acpihp_slot(d);
+	u32 cap = slot->capabilities;
+
+	sz = snprintf(buf, PAGE_SIZE, "%s%s%s%s%s%s",
+		(cap & ACPIHP_SLOT_CAP_ONLINE) ? "online," : "",
+		(cap & ACPIHP_SLOT_CAP_OFFLINE) ? "offline," : "",
+		(cap & ACPIHP_SLOT_CAP_POWERON) ? "poweron," : "",
+		(cap & ACPIHP_SLOT_CAP_POWEROFF) ? "poweroff," : "",
+		(cap & ACPIHP_SLOT_CAP_HOTPLUG) ? "hotplug," : "",
+		(cap & ACPIHP_SLOT_CAP_MIGRATE) ? "migrate," : "");
+	BUG_ON(sz == 0);
+	if (sz)
+		buf[--sz] = '\n';
+
+	return sz + 1;
+}
+
+struct device_attribute acpihp_slot_dev_attrs[] = {
+	__ATTR(object, S_IRUGO, acpihp_slot_object_show, NULL),
+	__ATTR(type, S_IRUGO, acpihp_slot_type_show, NULL),
+	__ATTR(state, S_IRUGO, acpihp_slot_state_show, NULL),
+	__ATTR(status, S_IRUGO, acpihp_slot_status_show, NULL),
+	__ATTR(capabilities, S_IRUGO, acpihp_slot_capabilities_show, NULL),
+	__ATTR_NULL
+};
+
+/*
+ * The device class to support ACPI hotplug slots.
+ * The hotplug slot enumerator should associate all discovered slots with
+ * this class and all hotplug drivers should register onto this class too.
+ */
+struct class acpihp_slot_class = {
+	.name		= "acpihp",
+	.dev_release	= &acpihp_slot_release,
+	.dev_attrs	= acpihp_slot_dev_attrs,
+};
+EXPORT_SYMBOL_GPL(acpihp_slot_class);
+
+int acpihp_register_class(void)
+{
+	int retval = 0;
+	struct kset *acpi_bus_kset;
+
+	mutex_lock(&acpihp_mutex);
+	if (acpihp_class_count == 0) {
+		acpi_bus_kset = bus_get_kset(&acpi_bus_type);
+		acpihp_slot_kset = kset_create_and_add("acpihp", NULL,
+						       &acpi_bus_kset->kobj);
+		if (!acpihp_slot_kset) {
+			ACPIHP_WARN("fails to create kset.\n");
+			retval = -ENOMEM;
+			goto out_unlock;
+		}
+
+		retval = class_register(&acpihp_slot_class);
+		if (retval) {
+			ACPIHP_WARN("fails to register acpihp_slot_class.\n");
+			kset_unregister(acpihp_slot_kset);
+			goto out_unlock;
+		}
+	}
+	acpihp_class_count++;
+out_unlock:
+	mutex_unlock(&acpihp_mutex);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(acpihp_register_class);
+
+void acpihp_unregister_class(void)
+{
+	mutex_lock(&acpihp_mutex);
+	BUG_ON(acpihp_class_count == 0);
+	--acpihp_class_count;
+	if (acpihp_class_count == 0) {
+		class_unregister(&acpihp_slot_class);
+		kset_unregister(acpihp_slot_kset);
+		acpihp_slot_kset = NULL;
+	}
+	mutex_unlock(&acpihp_mutex);
+}
+EXPORT_SYMBOL_GPL(acpihp_unregister_class);
+
+int acpihp_debug;
+EXPORT_SYMBOL_GPL(acpihp_debug);
+module_param_named(debug, acpihp_debug, int, S_IRUGO | S_IWUSR);
diff --git a/include/acpi/acpi_hotplug.h b/include/acpi/acpi_hotplug.h
new file mode 100644
index 0000000..09c935e
--- /dev/null
+++ b/include/acpi/acpi_hotplug.h
@@ -0,0 +1,191 @@
+/*
+ * Copyright (C) 2011 Huawei Tech. Co., Ltd.
+ * Copyright (C) 2011 Jiang Liu <jiang.liu@huawei.com>
+ * Copyright (C) 2011 Gaohuai Han <hangaohuai@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
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#ifndef	__ACPI_HOTPLUG_H__
+#define	__ACPI_HOTPLUG_H__
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/klist.h>
+#include <acpi/acpi.h>
+#include <acpi/acpi_drivers.h>
+
+#ifdef	CONFIG_ACPI_HOTPLUG
+
+#define	ACPIHP_SLOT_NAME_MAX_SIZE		16
+
+/* Types of system devices supported by the ACPI hotplug framework. */
+enum acpihp_dev_type {
+	ACPIHP_DEV_TYPE_UNKNOWN = 0,	/* Unknown device type */
+	ACPIHP_DEV_TYPE_CONTAINER,	/* ACPI container device */
+	ACPIHP_DEV_TYPE_MEM,		/* Memory device */
+	ACPIHP_DEV_TYPE_CPU,		/* Logical CPU device */
+	ACPIHP_DEV_TYPE_IOAPIC,		/* IOAPIC/IOxAPIC/IOSAPIC */
+	ACPIHP_DEV_TYPE_HOST_BRIDGE,	/* PCI/PCIe host bridge */
+	ACPIHP_DEV_TYPE_MAX
+};
+
+/*
+ * ACPI hotplug slot is an abstraction of receptacles where a group of
+ * system devices could be attached, just like PCI slot in PCI hotplug.
+ */
+enum acpihp_slot_type {
+	ACPIHP_SLOT_TYPE_UNKNOWN = 0,	/* Unknown slot type */
+	ACPIHP_SLOT_TYPE_COMMON,	/* Generic hotplug slot */
+	ACPIHP_SLOT_TYPE_NODE,		/* Node hosts CPU, memory & IO device */
+	ACPIHP_SLOT_TYPE_SYSTEM_BOARD,	/* System board hosts CPU & memory */
+	ACPIHP_SLOT_TYPE_CPU,		/* CPU board */
+	ACPIHP_SLOT_TYPE_MEM,		/* Memory board */
+	ACPIHP_SLOT_TYPE_IOX,		/* IO eXtension board */
+	ACPIHP_SLOT_TYPE_MAX
+};
+
+/*
+ * States of ACPI hotplug slot:
+ *                     (POWERON)      (CONNECT)      (CONFIGURE)
+ * [ABSENT] <-> [PRESENT] <-> [POWERED] <-> [CONNECTED] <-> [CONFIGURED]
+ *                     (POWEROFF)    (DISCONNECT)   (UNCONFIGURE)
+ */
+enum acpihp_slot_state {
+	ACPIHP_SLOT_STATE_UNKNOWN = 0,
+	ACPIHP_SLOT_STATE_ABSENT,	/* slot is empty. */
+	ACPIHP_SLOT_STATE_PRESENT,	/* slot is populated. */
+	ACPIHP_SLOT_STATE_POWERED,	/* attached devices are powered. */
+	ACPIHP_SLOT_STATE_CONNECTED,	/* ACPI device nodes created. */
+	ACPIHP_SLOT_STATE_CONFIGURED,	/* attached devices are configured. */
+	ACPIHP_SLOT_STATE_POWERING_ON,	/* powering devices on */
+	ACPIHP_SLOT_STATE_POWERING_OFF,	/* powering devices off */
+	ACPIHP_SLOT_STATE_CONNECTING,	/* creating ACPI device nodes */
+	ACPIHP_SLOT_STATE_DISCONNECTING,/* destroying ACPI device nodes */
+	ACPIHP_SLOT_STATE_CONFIGURING,	/* configuring devices */
+	ACPIHP_SLOT_STATE_UNCONFIGURING,/* unconfigure devices */
+	ACPIHP_SLOT_STATE_MAX
+};
+
+#define	ACPIHP_SLOT_FLAG_IRREMOVABLE	0x1 /* Attached devices can't be
+					     * removed.
+					     */
+#define	ACPIHP_SLOT_FLAG_FAULT		0x2 /* Attached devices have
+					     * encountered serious problem.
+					     */
+#define	ACPIHP_SLOT_STATUS_MASK		0x3
+#define	ACPIHP_SLOT_FLAG_REGISTERED	0x80000000 /* Slot device registered */
+
+/*
+ * ACPI hotplug slot capabilites.
+ */
+#define	ACPIHP_SLOT_CAP_ONLINE		0x1  /* Logical online */
+#define	ACPIHP_SLOT_CAP_OFFLINE		0x2  /* Logical offline */
+#define	ACPIHP_SLOT_CAP_POWERON		0x4  /* Powering on */
+#define	ACPIHP_SLOT_CAP_POWEROFF	0x8  /* Powering off */
+#define	ACPIHP_SLOT_CAP_HOTPLUG		0x10 /* Physical hotplug */
+#define	ACPIHP_SLOT_CAP_MIGRATE		0x20 /* Memory migration */
+
+/*
+ * Callback hooks provided by the platform dependent slot driver for the
+ * platform independent ACPI hotplug driver to manage ACPI hotplug slots.
+ */
+struct acpihp_slot_ops {
+	acpi_status (*init)(void);
+	void (*fini)(void);
+	acpi_status (*check)(acpi_handle handle);
+	acpi_status (*get_capabilities)(acpi_handle handle, u32 *capability);
+	acpi_status (*poweron)(acpi_handle handle);
+	acpi_status (*poweroff)(acpi_handle handle);
+	struct module			*owner;
+	char				*desc;
+};
+
+/* Device structure for ACPI hotplug slots. */
+struct acpihp_slot {
+	struct device			dev;
+	acpi_handle			handle;
+	enum acpihp_slot_type		type;
+	enum acpihp_slot_state		state;
+	u32				flags;
+	u32				capabilities;
+	struct acpihp_slot		*parent;
+	struct acpihp_slot_ops		*slot_ops;
+	struct mutex			slot_mutex;
+	struct list_head		slot_list;
+	struct list_head		slot_id_list;
+	struct list_head		drvdata_list;
+	struct klist			dev_lists[ACPIHP_DEV_TYPE_MAX];
+	char				*full_path;
+	char				name[ACPIHP_SLOT_NAME_MAX_SIZE];
+};
+
+/* Device class for ACPI hotplug slots */
+extern struct class acpihp_slot_class;
+
+/* Register the ACPI hotplug slot class driver */
+extern int acpihp_register_class(void);
+
+/* Unregister the ACPI hotplug slot class driver */
+extern void acpihp_unregister_class(void);
+
+/* Utility routines */
+extern int acpihp_dev_get_type(acpi_handle handle, enum acpihp_dev_type *type);
+extern bool acpihp_dev_match_ids(struct acpi_device_info *infop, char **ids);
+extern char *acpihp_get_slot_type_name(enum acpihp_slot_type type);
+
+/* Mark/unmark an ACPI object as an ACPI hotplug slot. */
+extern acpi_status acpihp_mark_slot(acpi_handle handle,
+				    struct acpihp_slot *slot);
+extern acpi_status acpihp_unmark_slot(acpi_handle handle);
+
+/* Check whether the ACPI object is a hotplug slot. */
+extern bool acpihp_check_slot(acpi_handle handle);
+
+/* Interfaces to manage ACPI hotplug slots */
+extern struct acpihp_slot *acpihp_create_slot(acpi_handle handle, char *name);
+extern int acpihp_register_slot(struct acpihp_slot *slot);
+extern void acpihp_unregister_slot(struct acpihp_slot *slot);
+extern struct acpihp_slot *acpihp_slot_get(struct acpihp_slot *slot);
+extern void acpihp_slot_put(struct acpihp_slot *slot);
+extern bool acpihp_get_slot(acpi_handle handle, struct acpihp_slot **slot);
+
+/* Platform dependent hotplug hooks */
+extern acpi_status acpihp_slot_get_capabilities(struct acpihp_slot *slot,
+						u32 *capability);
+extern acpi_status acpihp_slot_poweron(struct acpihp_slot *slot);
+extern acpi_status acpihp_slot_poweroff(struct acpihp_slot *slot);
+
+extern int acpihp_debug;
+
+#define ACPIHP_DEBUG(fmt, ...) \
+	do { \
+		if (acpihp_debug & 0x01) \
+			pr_warn("acpihp@%s: " fmt,  __func__, ##__VA_ARGS__); \
+	} while (0)
+
+#define	ACPIHP_INFO(fmt, ...)	pr_info("acpihp: " fmt, ##__VA_ARGS__)
+#define	ACPIHP_WARN(fmt, ...)	pr_warn("acpihp: " fmt, ##__VA_ARGS__)
+#define	ACPIHP_ERROR(fmt, ...)	pr_err("acpihp: " fmt, ##__VA_ARGS__)
+
+#endif	/* CONFIG_ACPI_HOTPLUG */
+
+#endif	/* __ACPI_HOTPLUG_H__ */
-- 
1.7.9.5