ACPI / processor: Use common hotplug infrastructure

Split the ACPI processor driver into two parts, one that is
non-modular, resides in the ACPI core and handles the enumeration
and hotplug of processors and one that implements the rest of the
existing processor driver functionality.

The non-modular part uses an ACPI scan handler object to enumerate
processors on the basis of information provided by the ACPI namespace
and to hook up with the common ACPI hotplug infrastructure.  It also
populates the ACPI handle of each processor device having a
corresponding object in the ACPI namespace, which allows the driver
proper to bind to those devices, and makes the driver bind to them
if it is readily available (i.e. loaded) when the scan handler's
.attach() routine is running.

There are a few reasons to make this change.

First, switching the ACPI processor driver to using the common ACPI
hotplug infrastructure reduces code duplication and size considerably,
even though a new file is created along with a header comment etc.

Second, since the common hotplug code attempts to offline devices
before starting the (non-reversible) removal procedure, it will abort
(and possibly roll back) hot-remove operations involving processors
if cpu_down() returns an error code for one of them instead of
continuing them blindly (if /sys/firmware/acpi/hotplug/force_remove
is unset).  That is a more desirable behavior than what the current
code does.

Finally, the separation of the scan/hotplug part from the driver
proper makes it possible to simplify the driver's .remove() routine,
because it doesn't need to worry about the possible cleanup related
to processor removal any more (the scan/hotplug part is responsible
for that now) and can handle device removal and driver removal
symmetricaly (i.e. as appropriate).

Some user-visible changes in sysfs are made (for example, the
'sysdev' link from the ACPI device node to the processor device's
directory is gone and a 'physical_node' link is present instead
and a corresponding 'firmware_node' is present in the processor
device's directory, the processor driver is now visible under
/sys/bus/cpu/drivers/ and bound to the processor device), but
that shouldn't affect the functionality that users care about
(frequency scaling, C-states and thermal management).

Tested on my venerable Toshiba Portege R500.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>

1 files changed, 78 insertions, 729 deletions

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index c266cdc11784..ac28f18823b3 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -1,11 +1,13 @@
 /*
- * acpi_processor.c - ACPI Processor Driver ($Revision: 71 $)
+ * processor_driver.c - ACPI Processor Driver
  *
  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
  *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
  *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
  *  			- Added processor hotplug support
+ *  Copyright (C) 2013, Intel Corporation
+ *                      Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *
@@ -24,52 +26,29 @@
  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- *  TBD:
- *	1. Make # power states dynamic.
- *	2. Support duty_cycle values that span bit 4.
- *	3. Optimize by having scheduler determine business instead of
- *	   having us try to calculate it here.
- *	4. Need C1 timing -- must modify kernel (IRQ handler) to get this.
  */
 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
-#include <linux/types.h>
-#include <linux/pci.h>
-#include <linux/pm.h>
 #include <linux/cpufreq.h>
 #include <linux/cpu.h>
-#include <linux/dmi.h>
-#include <linux/moduleparam.h>
 #include <linux/cpuidle.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
-#include <linux/memory_hotplug.h>
-
-#include <asm/io.h>
-#include <asm/cpu.h>
-#include <asm/delay.h>
-#include <asm/uaccess.h>
-#include <asm/processor.h>
-#include <asm/smp.h>
-#include <asm/acpi.h>
-
-#include <acpi/acpi_bus.h>
-#include <acpi/acpi_drivers.h>
+
 #include <acpi/processor.h>
 
+#include "internal.h"
+
 #define PREFIX "ACPI: "
 
-#define ACPI_PROCESSOR_CLASS		"processor"
-#define ACPI_PROCESSOR_DEVICE_NAME	"Processor"
 #define ACPI_PROCESSOR_FILE_INFO	"info"
 #define ACPI_PROCESSOR_FILE_THROTTLING	"throttling"
 #define ACPI_PROCESSOR_FILE_LIMIT	"limit"
 #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
 #define ACPI_PROCESSOR_NOTIFY_POWER	0x81
 #define ACPI_PROCESSOR_NOTIFY_THROTTLING	0x82
-#define ACPI_PROCESSOR_DEVICE_HID	"ACPI0007"
 
 #define ACPI_PROCESSOR_LIMIT_USER	0
 #define ACPI_PROCESSOR_LIMIT_THERMAL	1
@@ -81,12 +60,8 @@ MODULE_AUTHOR("Paul Diefenbaugh");
 MODULE_DESCRIPTION("ACPI Processor Driver");
 MODULE_LICENSE("GPL");
 
-static int acpi_processor_add(struct acpi_device *device);
-static int acpi_processor_remove(struct acpi_device *device);
-static void acpi_processor_notify(struct acpi_device *device, u32 event);
-static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr);
-static int acpi_processor_handle_eject(struct acpi_processor *pr);
-static int acpi_processor_start(struct acpi_processor *pr);
+static int acpi_processor_start(struct device *dev);
+static int acpi_processor_stop(struct device *dev);
 
 static const struct acpi_device_id processor_device_ids[] = {
 	{ACPI_PROCESSOR_OBJECT_HID, 0},
@@ -95,295 +70,27 @@ static const struct acpi_device_id processor_device_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, processor_device_ids);
 
-static struct acpi_driver acpi_processor_driver = {
+static struct device_driver acpi_processor_driver = {
 	.name = "processor",
-	.class = ACPI_PROCESSOR_CLASS,
-	.ids = processor_device_ids,
-	.ops = {
-		.add = acpi_processor_add,
-		.remove = acpi_processor_remove,
-		.notify = acpi_processor_notify,
-		},
+	.bus = &cpu_subsys,
+	.acpi_match_table = processor_device_ids,
+	.probe = acpi_processor_start,
+	.remove = acpi_processor_stop,
 };
 
-#define INSTALL_NOTIFY_HANDLER		1
-#define UNINSTALL_NOTIFY_HANDLER	2
-
 DEFINE_PER_CPU(struct acpi_processor *, processors);
 EXPORT_PER_CPU_SYMBOL(processors);
 
-struct acpi_processor_errata errata __read_mostly;
-
-/* --------------------------------------------------------------------------
-                                Errata Handling
-   -------------------------------------------------------------------------- */
-
-static int acpi_processor_errata_piix4(struct pci_dev *dev)
+static void acpi_processor_notify(acpi_handle handle, u32 event, void *data)
 {
-	u8 value1 = 0;
-	u8 value2 = 0;
-
-
-	if (!dev)
-		return -EINVAL;
-
-	/*
-	 * Note that 'dev' references the PIIX4 ACPI Controller.
-	 */
-
-	switch (dev->revision) {
-	case 0:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4 A-step\n"));
-		break;
-	case 1:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4 B-step\n"));
-		break;
-	case 2:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4E\n"));
-		break;
-	case 3:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found PIIX4M\n"));
-		break;
-	default:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found unknown PIIX4\n"));
-		break;
-	}
-
-	switch (dev->revision) {
-
-	case 0:		/* PIIX4 A-step */
-	case 1:		/* PIIX4 B-step */
-		/*
-		 * See specification changes #13 ("Manual Throttle Duty Cycle")
-		 * and #14 ("Enabling and Disabling Manual Throttle"), plus
-		 * erratum #5 ("STPCLK# Deassertion Time") from the January
-		 * 2002 PIIX4 specification update.  Applies to only older
-		 * PIIX4 models.
-		 */
-		errata.piix4.throttle = 1;
-
-	case 2:		/* PIIX4E */
-	case 3:		/* PIIX4M */
-		/*
-		 * See erratum #18 ("C3 Power State/BMIDE and Type-F DMA
-		 * Livelock") from the January 2002 PIIX4 specification update.
-		 * Applies to all PIIX4 models.
-		 */
-
-		/*
-		 * BM-IDE
-		 * ------
-		 * Find the PIIX4 IDE Controller and get the Bus Master IDE
-		 * Status register address.  We'll use this later to read
-		 * each IDE controller's DMA status to make sure we catch all
-		 * DMA activity.
-		 */
-		dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
-				     PCI_DEVICE_ID_INTEL_82371AB,
-				     PCI_ANY_ID, PCI_ANY_ID, NULL);
-		if (dev) {
-			errata.piix4.bmisx = pci_resource_start(dev, 4);
-			pci_dev_put(dev);
-		}
-
-		/*
-		 * Type-F DMA
-		 * ----------
-		 * Find the PIIX4 ISA Controller and read the Motherboard
-		 * DMA controller's status to see if Type-F (Fast) DMA mode
-		 * is enabled (bit 7) on either channel.  Note that we'll
-		 * disable C3 support if this is enabled, as some legacy
-		 * devices won't operate well if fast DMA is disabled.
-		 */
-		dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
-				     PCI_DEVICE_ID_INTEL_82371AB_0,
-				     PCI_ANY_ID, PCI_ANY_ID, NULL);
-		if (dev) {
-			pci_read_config_byte(dev, 0x76, &value1);
-			pci_read_config_byte(dev, 0x77, &value2);
-			if ((value1 & 0x80) || (value2 & 0x80))
-				errata.piix4.fdma = 1;
-			pci_dev_put(dev);
-		}
-
-		break;
-	}
-
-	if (errata.piix4.bmisx)
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "Bus master activity detection (BM-IDE) erratum enabled\n"));
-	if (errata.piix4.fdma)
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "Type-F DMA livelock erratum (C3 disabled)\n"));
-
-	return 0;
-}
-
-static int acpi_processor_errata(struct acpi_processor *pr)
-{
-	int result = 0;
-	struct pci_dev *dev = NULL;
-
-
-	if (!pr)
-		return -EINVAL;
-
-	/*
-	 * PIIX4
-	 */
-	dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
-			     PCI_DEVICE_ID_INTEL_82371AB_3, PCI_ANY_ID,
-			     PCI_ANY_ID, NULL);
-	if (dev) {
-		result = acpi_processor_errata_piix4(dev);
-		pci_dev_put(dev);
-	}
-
-	return result;
-}
-
-/* --------------------------------------------------------------------------
-                                 Driver Interface
-   -------------------------------------------------------------------------- */
-
-static int acpi_processor_get_info(struct acpi_device *device)
-{
-	acpi_status status = 0;
-	union acpi_object object = { 0 };
-	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
+	struct acpi_device *device = data;
 	struct acpi_processor *pr;
-	int cpu_index, device_declaration = 0;
-	static int cpu0_initialized;
-
-	pr = acpi_driver_data(device);
-	if (!pr)
-		return -EINVAL;
-
-	if (num_online_cpus() > 1)
-		errata.smp = TRUE;
-
-	acpi_processor_errata(pr);
-
-	/*
-	 * Check to see if we have bus mastering arbitration control.  This
-	 * is required for proper C3 usage (to maintain cache coherency).
-	 */
-	if (acpi_gbl_FADT.pm2_control_block && acpi_gbl_FADT.pm2_control_length) {
-		pr->flags.bm_control = 1;
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "Bus mastering arbitration control present\n"));
-	} else
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "No bus mastering arbitration control\n"));
-
-	if (!strcmp(acpi_device_hid(device), ACPI_PROCESSOR_OBJECT_HID)) {
-		/* Declared with "Processor" statement; match ProcessorID */
-		status = acpi_evaluate_object(pr->handle, NULL, NULL, &buffer);
-		if (ACPI_FAILURE(status)) {
-			dev_err(&device->dev,
-				"Failed to evaluate processor object (0x%x)\n",
-				status);
-			return -ENODEV;
-		}
-
-		/*
-		 * TBD: Synch processor ID (via LAPIC/LSAPIC structures) on SMP.
-		 *      >>> 'acpi_get_processor_id(acpi_id, &id)' in
-		 *      arch/xxx/acpi.c
-		 */
-		pr->acpi_id = object.processor.proc_id;
-	} else {
-		/*
-		 * Declared with "Device" statement; match _UID.
-		 * Note that we don't handle string _UIDs yet.
-		 */
-		unsigned long long value;
-		status = acpi_evaluate_integer(pr->handle, METHOD_NAME__UID,
-						NULL, &value);
-		if (ACPI_FAILURE(status)) {
-			dev_err(&device->dev,
-				"Failed to evaluate processor _UID (0x%x)\n",
-				status);
-			return -ENODEV;
-		}
-		device_declaration = 1;
-		pr->acpi_id = value;
-	}
-	cpu_index = acpi_get_cpuid(pr->handle, device_declaration, pr->acpi_id);
-
-	/* Handle UP system running SMP kernel, with no LAPIC in MADT */
-	if (!cpu0_initialized && (cpu_index == -1) &&
-	    (num_online_cpus() == 1)) {
-		cpu_index = 0;
-	}
-
-	cpu0_initialized = 1;
-
-	pr->id = cpu_index;
-
-	/*
-	 *  Extra Processor objects may be enumerated on MP systems with
-	 *  less than the max # of CPUs. They should be ignored _iff
-	 *  they are physically not present.
-	 */
-	if (pr->id == -1) {
-		if (ACPI_FAILURE(acpi_processor_hotadd_init(pr)))
-			return -ENODEV;
-	}
-	/*
-	 * On some boxes several processors use the same processor bus id.
-	 * But they are located in different scope. For example:
-	 * \_SB.SCK0.CPU0
-	 * \_SB.SCK1.CPU0
-	 * Rename the processor device bus id. And the new bus id will be
-	 * generated as the following format:
-	 * CPU+CPU ID.
-	 */
-	sprintf(acpi_device_bid(device), "CPU%X", pr->id);
-	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Processor [%d:%d]\n", pr->id,
-			  pr->acpi_id));
-
-	if (!object.processor.pblk_address)
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No PBLK (NULL address)\n"));
-	else if (object.processor.pblk_length != 6)
-		dev_err(&device->dev, "Invalid PBLK length [%d]\n",
-			    object.processor.pblk_length);
-	else {
-		pr->throttling.address = object.processor.pblk_address;
-		pr->throttling.duty_offset = acpi_gbl_FADT.duty_offset;
-		pr->throttling.duty_width = acpi_gbl_FADT.duty_width;
-
-		pr->pblk = object.processor.pblk_address;
-
-		/*
-		 * We don't care about error returns - we just try to mark
-		 * these reserved so that nobody else is confused into thinking
-		 * that this region might be unused..
-		 *
-		 * (In particular, allocating the IO range for Cardbus)
-		 */
-		request_region(pr->throttling.address, 6, "ACPI CPU throttle");
-	}
-
-	/*
-	 * If ACPI describes a slot number for this CPU, we can use it
-	 * ensure we get the right value in the "physical id" field
-	 * of /proc/cpuinfo
-	 */
-	status = acpi_evaluate_object(pr->handle, "_SUN", NULL, &buffer);
-	if (ACPI_SUCCESS(status))
-		arch_fix_phys_package_id(pr->id, object.integer.value);
-
-	return 0;
-}
-
-static DEFINE_PER_CPU(void *, processor_device_array);
-
-static void acpi_processor_notify(struct acpi_device *device, u32 event)
-{
-	struct acpi_processor *pr = acpi_driver_data(device);
 	int saved;
 
+	if (device->handle != handle)
+		return;
+
+	pr = acpi_driver_data(device);
 	if (!pr)
 		return;
 
@@ -420,55 +127,62 @@ static void acpi_processor_notify(struct acpi_device *device, u32 event)
 	return;
 }
 
-static int acpi_cpu_soft_notify(struct notifier_block *nfb,
-		unsigned long action, void *hcpu)
+static __cpuinit int __acpi_processor_start(struct acpi_device *device);
+
+static int __cpuinit acpi_cpu_soft_notify(struct notifier_block *nfb,
+					  unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
 	struct acpi_processor *pr = per_cpu(processors, cpu);
+	struct acpi_device *device;
 
-	if (action == CPU_ONLINE && pr) {
-		/* CPU got physically hotplugged and onlined the first time:
-		 * Initialize missing things
+	if (!pr || acpi_bus_get_device(pr->handle, &device))
+		return NOTIFY_DONE;
+
+	if (action == CPU_ONLINE) {
+		/*
+		 * CPU got physically hotplugged and onlined for the first time:
+		 * Initialize missing things.
 		 */
 		if (pr->flags.need_hotplug_init) {
+			int ret;
+
 			pr_info("Will online and init hotplugged CPU: %d\n",
 				pr->id);
-			WARN(acpi_processor_start(pr), "Failed to start CPU:"
-				" %d\n", pr->id);
 			pr->flags.need_hotplug_init = 0;
-		/* Normal CPU soft online event */
+			ret = __acpi_processor_start(device);
+			WARN(ret, "Failed to start CPU: %d\n", pr->id);
 		} else {
+			/* Normal CPU soft online event. */
 			acpi_processor_ppc_has_changed(pr, 0);
 			acpi_processor_hotplug(pr);
 			acpi_processor_reevaluate_tstate(pr, action);
 			acpi_processor_tstate_has_changed(pr);
 		}
-	}
-	if (action == CPU_DEAD && pr) {
-		/* invalidate the flag.throttling after one CPU is offline */
+	} else if (action == CPU_DEAD) {
+		/* Invalidate flag.throttling after the CPU is offline. */
 		acpi_processor_reevaluate_tstate(pr, action);
 	}
 	return NOTIFY_OK;
 }
 
-static struct notifier_block acpi_cpu_notifier =
+static struct notifier_block __refdata acpi_cpu_notifier =
 {
 	    .notifier_call = acpi_cpu_soft_notify,
 };
 
-/*
- * acpi_processor_start() is called by the cpu_hotplug_notifier func:
- * acpi_cpu_soft_notify(). Getting it __cpuinit{data} is difficult, the
- * root cause seem to be that acpi_processor_uninstall_hotplug_notify()
- * is in the module_exit (__exit) func. Allowing acpi_processor_start()
- * to not be in __cpuinit section, but being called from __cpuinit funcs
- * via __ref looks like the right thing to do here.
- */
-static __ref int acpi_processor_start(struct acpi_processor *pr)
+static __cpuinit int __acpi_processor_start(struct acpi_device *device)
 {
-	struct acpi_device *device = per_cpu(processor_device_array, pr->id);
+	struct acpi_processor *pr = acpi_driver_data(device);
+	acpi_status status;
 	int result = 0;
 
+	if (!pr)
+		return -ENODEV;
+
+	if (pr->flags.need_hotplug_init)
+		return 0;
+
 #ifdef CONFIG_CPU_FREQ
 	acpi_processor_ppc_has_changed(pr, 0);
 	acpi_processor_load_module(pr);
@@ -506,129 +220,48 @@ static __ref int acpi_processor_start(struct acpi_processor *pr)
 		goto err_remove_sysfs_thermal;
 	}
 
-	return 0;
+	status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+					     acpi_processor_notify, device);
+	if (ACPI_SUCCESS(status))
+		return 0;
 
-err_remove_sysfs_thermal:
+	sysfs_remove_link(&pr->cdev->device.kobj, "device");
+ err_remove_sysfs_thermal:
 	sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
-err_thermal_unregister:
+ err_thermal_unregister:
 	thermal_cooling_device_unregister(pr->cdev);
-err_power_exit:
+ err_power_exit:
 	acpi_processor_power_exit(pr);
-
 	return result;
 }
 
-/*
- * Do not put anything in here which needs the core to be online.
- * For example MSR access or setting up things which check for cpuinfo_x86
- * (cpu_data(cpu)) values, like CPU feature flags, family, model, etc.
- * Such things have to be put in and set up above in acpi_processor_start()
- */
-static int __cpuinit acpi_processor_add(struct acpi_device *device)
+static int __cpuinit acpi_processor_start(struct device *dev)
 {
-	struct acpi_processor *pr = NULL;
-	int result = 0;
-	struct device *dev;
-
-	pr = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
-	if (!pr)
-		return -ENOMEM;
+	struct acpi_device *device;
 
-	if (!zalloc_cpumask_var(&pr->throttling.shared_cpu_map, GFP_KERNEL)) {
-		result = -ENOMEM;
-		goto err_free_pr;
-	}
-
-	pr->handle = device->handle;
-	strcpy(acpi_device_name(device), ACPI_PROCESSOR_DEVICE_NAME);
-	strcpy(acpi_device_class(device), ACPI_PROCESSOR_CLASS);
-	device->driver_data = pr;
-
-	result = acpi_processor_get_info(device);
-	if (result) {
-		/* Processor is physically not present */
-		return 0;
-	}
-
-#ifdef CONFIG_SMP
-	if (pr->id >= setup_max_cpus && pr->id != 0)
-		return 0;
-#endif
-
-	BUG_ON(pr->id >= nr_cpu_ids);
-
-	/*
-	 * Buggy BIOS check
-	 * ACPI id of processors can be reported wrongly by the BIOS.
-	 * Don't trust it blindly
-	 */
-	if (per_cpu(processor_device_array, pr->id) != NULL &&
-	    per_cpu(processor_device_array, pr->id) != device) {
-		dev_warn(&device->dev,
-			"BIOS reported wrong ACPI id %d for the processor\n",
-			pr->id);
-		result = -ENODEV;
-		goto err_free_cpumask;
-	}
-	per_cpu(processor_device_array, pr->id) = device;
-
-	per_cpu(processors, pr->id) = pr;
+	if (acpi_bus_get_device(ACPI_HANDLE(dev), &device))
+		return -ENODEV;
 
-	dev = get_cpu_device(pr->id);
-	if (sysfs_create_link(&device->dev.kobj, &dev->kobj, "sysdev")) {
-		result = -EFAULT;
-		goto err_clear_processor;
-	}
-
-	/*
-	 * Do not start hotplugged CPUs now, but when they
-	 * are onlined the first time
-	 */
-	if (pr->flags.need_hotplug_init)
-		return 0;
-
-	result = acpi_processor_start(pr);
-	if (result)
-		goto err_remove_sysfs;
-
-	return 0;
-
-err_remove_sysfs:
-	sysfs_remove_link(&device->dev.kobj, "sysdev");
-err_clear_processor:
-	/*
-	 * processor_device_array is not cleared to allow checks for buggy BIOS
-	 */ 
-	per_cpu(processors, pr->id) = NULL;
-err_free_cpumask:
-	free_cpumask_var(pr->throttling.shared_cpu_map);
-err_free_pr:
-	kfree(pr);
-	return result;
+	return __acpi_processor_start(device);
 }
 
-static int acpi_processor_remove(struct acpi_device *device)
+static int acpi_processor_stop(struct device *dev)
 {
-	struct acpi_processor *pr = NULL;
+	struct acpi_device *device;
+	struct acpi_processor *pr;
 
+	if (acpi_bus_get_device(ACPI_HANDLE(dev), &device))
+		return 0;
 
-	if (!device || !acpi_driver_data(device))
-		return -EINVAL;
+	acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+				   acpi_processor_notify);
 
 	pr = acpi_driver_data(device);
-
-	if (pr->id >= nr_cpu_ids)
-		goto free;
-
-	if (device->removal_type == ACPI_BUS_REMOVAL_EJECT) {
-		if (acpi_processor_handle_eject(pr))
-			return -EINVAL;
-	}
+	if (!pr)
+		return 0;
 
 	acpi_processor_power_exit(pr);
 
-	sysfs_remove_link(&device->dev.kobj, "sysdev");
-
 	if (pr->cdev) {
 		sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
 		sysfs_remove_link(&pr->cdev->device.kobj, "device");
@@ -637,331 +270,47 @@ static int acpi_processor_remove(struct acpi_device *device)
 	}
 
 	per_cpu(processors, pr->id) = NULL;
-	per_cpu(processor_device_array, pr->id) = NULL;
-	try_offline_node(cpu_to_node(pr->id));
-
-free:
-	free_cpumask_var(pr->throttling.shared_cpu_map);
-	kfree(pr);
-
 	return 0;
 }
 
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
-/****************************************************************************
- * 	Acpi processor hotplug support 				       	    *
- ****************************************************************************/
-
-static int is_processor_present(acpi_handle handle)
-{
-	acpi_status status;
-	unsigned long long sta = 0;
-
-
-	status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
-
-	if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_PRESENT))
-		return 1;
-
-	/*
-	 * _STA is mandatory for a processor that supports hot plug
-	 */
-	if (status == AE_NOT_FOUND)
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				"Processor does not support hot plug\n"));
-	else
-		ACPI_EXCEPTION((AE_INFO, status,
-				"Processor Device is not present"));
-	return 0;
-}
-
-static void acpi_processor_hotplug_notify(acpi_handle handle,
-					  u32 event, void *data)
-{
-	struct acpi_device *device = NULL;
-	struct acpi_eject_event *ej_event = NULL;
-	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
-	acpi_status status;
-	int result;
-
-	acpi_scan_lock_acquire();
-
-	switch (event) {
-	case ACPI_NOTIFY_BUS_CHECK:
-	case ACPI_NOTIFY_DEVICE_CHECK:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-		"Processor driver received %s event\n",
-		       (event == ACPI_NOTIFY_BUS_CHECK) ?
-		       "ACPI_NOTIFY_BUS_CHECK" : "ACPI_NOTIFY_DEVICE_CHECK"));
-
-		if (!is_processor_present(handle))
-			break;
-
-		if (!acpi_bus_get_device(handle, &device))
-			break;
-
-		result = acpi_bus_scan(handle);
-		if (result) {
-			acpi_handle_err(handle, "Unable to add the device\n");
-			break;
-		}
-		result = acpi_bus_get_device(handle, &device);
-		if (result) {
-			acpi_handle_err(handle, "Missing device object\n");
-			break;
-		}
-		ost_code = ACPI_OST_SC_SUCCESS;
-		break;
-
-	case ACPI_NOTIFY_EJECT_REQUEST:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "received ACPI_NOTIFY_EJECT_REQUEST\n"));
-
-		if (acpi_bus_get_device(handle, &device)) {
-			acpi_handle_err(handle,
-				"Device don't exist, dropping EJECT\n");
-			break;
-		}
-		if (!acpi_driver_data(device)) {
-			acpi_handle_err(handle,
-				"Driver data is NULL, dropping EJECT\n");
-			break;
-		}
-
-		ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
-		if (!ej_event) {
-			acpi_handle_err(handle, "No memory, dropping EJECT\n");
-			break;
-		}
-
-		get_device(&device->dev);
-		ej_event->device = device;
-		ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
-		/* The eject is carried out asynchronously. */
-		status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
-						 ej_event);
-		if (ACPI_FAILURE(status)) {
-			put_device(&device->dev);
-			kfree(ej_event);
-			break;
-		}
-		goto out;
-
-	default:
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-				  "Unsupported event [0x%x]\n", event));
-
-		/* non-hotplug event; possibly handled by other handler */
-		goto out;
-	}
-
-	/* Inform firmware that the hotplug operation has completed */
-	(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
-
- out:
-	acpi_scan_lock_release();
-}
-
-static acpi_status is_processor_device(acpi_handle handle)
-{
-	struct acpi_device_info *info;
-	char *hid;
-	acpi_status status;
-
-	status = acpi_get_object_info(handle, &info);
-	if (ACPI_FAILURE(status))
-		return status;
-
-	if (info->type == ACPI_TYPE_PROCESSOR) {
-		kfree(info);
-		return AE_OK;	/* found a processor object */
-	}
-
-	if (!(info->valid & ACPI_VALID_HID)) {
-		kfree(info);
-		return AE_ERROR;
-	}
-
-	hid = info->hardware_id.string;
-	if ((hid == NULL) || strcmp(hid, ACPI_PROCESSOR_DEVICE_HID)) {
-		kfree(info);
-		return AE_ERROR;
-	}
-
-	kfree(info);
-	return AE_OK;	/* found a processor device object */
-}
-
-static acpi_status
-processor_walk_namespace_cb(acpi_handle handle,
-			    u32 lvl, void *context, void **rv)
-{
-	acpi_status status;
-	int *action = context;
-
-	status = is_processor_device(handle);
-	if (ACPI_FAILURE(status))
-		return AE_OK;	/* not a processor; continue to walk */
-
-	switch (*action) {
-	case INSTALL_NOTIFY_HANDLER:
-		acpi_install_notify_handler(handle,
-					    ACPI_SYSTEM_NOTIFY,
-					    acpi_processor_hotplug_notify,
-					    NULL);
-		break;
-	case UNINSTALL_NOTIFY_HANDLER:
-		acpi_remove_notify_handler(handle,
-					   ACPI_SYSTEM_NOTIFY,
-					   acpi_processor_hotplug_notify);
-		break;
-	default:
-		break;
-	}
-
-	/* found a processor; skip walking underneath */
-	return AE_CTRL_DEPTH;
-}
-
-static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
-{
-	acpi_handle handle = pr->handle;
-
-	if (!is_processor_present(handle)) {
-		return AE_ERROR;
-	}
-
-	if (acpi_map_lsapic(handle, &pr->id))
-		return AE_ERROR;
-
-	if (arch_register_cpu(pr->id)) {
-		acpi_unmap_lsapic(pr->id);
-		return AE_ERROR;
-	}
-
-	/* CPU got hot-plugged, but cpu_data is not initialized yet
-	 * Set flag to delay cpu_idle/throttling initialization
-	 * in:
-	 * acpi_processor_add()
-	 *   acpi_processor_get_info()
-	 * and do it when the CPU gets online the first time
-	 * TBD: Cleanup above functions and try to do this more elegant.
-	 */
-	pr_info("CPU %d got hotplugged\n", pr->id);
-	pr->flags.need_hotplug_init = 1;
-
-	return AE_OK;
-}
-
-static int acpi_processor_handle_eject(struct acpi_processor *pr)
-{
-	if (cpu_online(pr->id))
-		cpu_down(pr->id);
-
-	get_online_cpus();
-	/*
-	 * The cpu might become online again at this point. So we check whether
-	 * the cpu has been onlined or not. If the cpu became online, it means
-	 * that someone wants to use the cpu. So acpi_processor_handle_eject()
-	 * returns -EAGAIN.
-	 */
-	if (unlikely(cpu_online(pr->id))) {
-		put_online_cpus();
-		pr_warn("Failed to remove CPU %d, because other task "
-			"brought the CPU back online\n", pr->id);
-		return -EAGAIN;
-	}
-	arch_unregister_cpu(pr->id);
-	acpi_unmap_lsapic(pr->id);
-	put_online_cpus();
-	return (0);
-}
-#else
-static acpi_status acpi_processor_hotadd_init(struct acpi_processor *pr)
-{
-	return AE_ERROR;
-}
-static int acpi_processor_handle_eject(struct acpi_processor *pr)
-{
-	return (-EINVAL);
-}
-#endif
-
-static
-void acpi_processor_install_hotplug_notify(void)
-{
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
-	int action = INSTALL_NOTIFY_HANDLER;
-	acpi_walk_namespace(ACPI_TYPE_ANY,
-			    ACPI_ROOT_OBJECT,
-			    ACPI_UINT32_MAX,
-			    processor_walk_namespace_cb, NULL, &action, NULL);
-#endif
-	register_hotcpu_notifier(&acpi_cpu_notifier);
-}
-
-static
-void acpi_processor_uninstall_hotplug_notify(void)
-{
-#ifdef CONFIG_ACPI_HOTPLUG_CPU
-	int action = UNINSTALL_NOTIFY_HANDLER;
-	acpi_walk_namespace(ACPI_TYPE_ANY,
-			    ACPI_ROOT_OBJECT,
-			    ACPI_UINT32_MAX,
-			    processor_walk_namespace_cb, NULL, &action, NULL);
-#endif
-	unregister_hotcpu_notifier(&acpi_cpu_notifier);
-}
-
 /*
  * We keep the driver loaded even when ACPI is not running.
  * This is needed for the powernow-k8 driver, that works even without
  * ACPI, but needs symbols from this driver
  */
 
-static int __init acpi_processor_init(void)
+static int __init acpi_processor_driver_init(void)
 {
 	int result = 0;
 
 	if (acpi_disabled)
 		return 0;
 
-	result = acpi_bus_register_driver(&acpi_processor_driver);
+	result = driver_register(&acpi_processor_driver);
 	if (result < 0)
 		return result;
 
 	acpi_processor_syscore_init();
-
-	acpi_processor_install_hotplug_notify();
-
+	register_hotcpu_notifier(&acpi_cpu_notifier);
 	acpi_thermal_cpufreq_init();
-
 	acpi_processor_ppc_init();
-
 	acpi_processor_throttling_init();
-
 	return 0;
 }
 
-static void __exit acpi_processor_exit(void)
+static void __exit acpi_processor_driver_exit(void)
 {
 	if (acpi_disabled)
 		return;
 
 	acpi_processor_ppc_exit();
-
 	acpi_thermal_cpufreq_exit();
-
-	acpi_processor_uninstall_hotplug_notify();
-
+	unregister_hotcpu_notifier(&acpi_cpu_notifier);
 	acpi_processor_syscore_exit();
-
-	acpi_bus_unregister_driver(&acpi_processor_driver);
-
-	return;
+	driver_unregister(&acpi_processor_driver);
 }
 
-module_init(acpi_processor_init);
-module_exit(acpi_processor_exit);
+module_init(acpi_processor_driver_init);
+module_exit(acpi_processor_driver_exit);
 
 MODULE_ALIAS("processor");