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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-05-03 00:26:22 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-05-12 14:14:32 +0200
commitac212b6980d8d5eda705864fc5a8ecddc6d6eacc (patch)
tree9331543b7e4766df3bd13481c0f87aa884aa4cf6 /drivers/base/cpu.c
parent683058e315f00a216fd6c79df4f63bc9945ca434 (diff)
downloadop-kernel-dev-ac212b6980d8d5eda705864fc5a8ecddc6d6eacc.zip
op-kernel-dev-ac212b6980d8d5eda705864fc5a8ecddc6d6eacc.tar.gz
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>
Diffstat (limited to 'drivers/base/cpu.c')
-rw-r--r--drivers/base/cpu.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 25c8768..7431ba6 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -13,11 +13,21 @@
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/percpu.h>
+#include <linux/acpi.h>
#include "base.h"
static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
+static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
+{
+ /* ACPI style match is the only one that may succeed. */
+ if (acpi_driver_match_device(dev, drv))
+ return 1;
+
+ return 0;
+}
+
#ifdef CONFIG_HOTPLUG_CPU
static void change_cpu_under_node(struct cpu *cpu,
unsigned int from_nid, unsigned int to_nid)
@@ -98,6 +108,7 @@ static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
struct bus_type cpu_subsys = {
.name = "cpu",
.dev_name = "cpu",
+ .match = cpu_subsys_match,
#ifdef CONFIG_HOTPLUG_CPU
.online = cpu_subsys_online,
.offline = cpu_subsys_offline,
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