lkml.org 
[lkml]   [2011]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC PATCH V3 2/3] cpuidle: list based cpuidle driver registration and selection
Date
A cpuidle_driver structure represents a cpuidle driver like
acpi_idle, intel_idle providing low level idle routines.
A cpuidle_driver is global in nature as it provides routines
for all the CPUS. Each CPU registered with the cpuidle subsystem is
represented as a cpuidle_device. A cpuidle_device structure
points to the low level idle routines for that CPU provided by
a certain driver. In other words, a cpuidle driver creates a
cpuidle_device structure for each CPU that it registers with the
cpuidle subsystem. Whenever cpuidle idle loop is called, the cpuidle
subsystem picks the cpuidle_device structure for that cpu and
calls one of the low level idle routines through that structure.

In the current design, only one cpuidle_driver may be registered
and registration of any subsequent driver fails. The same registered
driver provides low level idle routines for each cpuidle_device.

A list based registration for cpuidle_driver provides a clean
mechanism for multiple subsystems/modules to register their own idle
routines and thus avoids using pm_idle.

This patch implements a list based registration for cpuidle
driver. Different drivers can be registered and the driver to
be used is selected based on a per driver priority. On a
cpuidle driver registration or unregistration cpuidle_device
structure for each CPU is changed. Each cpuidle_device points
to its driver to facilitate this registration and unregistration.

--------- ---------
|cpuidle| |cpuidle|
|driver |----------------------- |driver |
|default| |acpi |
--------- ---------
^ ^
| |
---------------------------- ---------------------------
^ ^ ^ ^
| | | |
| | | |
--------- --------- --------- ----------
|cpuidle| |cpuidle| |cpuidle| |cpuidle |
|device | |device | .... |device | |device | .....
| CPU0 | | CPU1 | |CPU0 | |CPU1 |
--------- --------- --------- ----------
Signed-off-by: Trinabh Gupta <trinabh@linux.vnet.ibm.com>
---
drivers/acpi/processor_idle.c | 2 +
drivers/cpuidle/Kconfig | 6 ++
drivers/cpuidle/cpuidle.c | 41 ++++++++++++---
drivers/cpuidle/driver.c | 114 ++++++++++++++++++++++++++++++++++++++---
include/linux/cpuidle.h | 3 +
5 files changed, 152 insertions(+), 14 deletions(-)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index dcb38f8..b53c7fb 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -964,6 +964,7 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
struct cpuidle_driver acpi_idle_driver = {
.name = "acpi_idle",
.owner = THIS_MODULE,
+ .priority = 10,
};

/**
@@ -985,6 +986,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
}

dev->cpu = pr->id;
+ dev->drv = &acpi_idle_driver;
for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
dev->states[i].name[0] = '\0';
dev->states[i].desc[0] = '\0';
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index e67c258..8cc73c8 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -19,3 +19,9 @@ config CPU_IDLE_GOV_MENU
bool
depends on CPU_IDLE && NO_HZ
default y
+
+config ARCH_USES_PMIDLE
+ bool
+ depends on CPUIDLE
+ depends on !X86
+ default y
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 9bf4640..dc472d8 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -109,6 +109,7 @@ void cpuidle_idle_call(void)
trace_power_end(smp_processor_id());
}

+#ifdef CONFIG_ARCH_USES_PMIDLE
/**
* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
*/
@@ -131,6 +132,10 @@ void cpuidle_uninstall_idle_handler(void)
cpuidle_kick_cpus();
}
}
+#else
+void cpuidle_install_idle_handler(void) {}
+void cpuidle_uninstall_idle_handler(void) {}
+#endif

/**
* cpuidle_pause_and_lock - temporarily disables CPUIDLE
@@ -284,9 +289,21 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();

+ if (dev->registered)
+ return 0;
if (!sys_dev)
return -EINVAL;
- if (!try_module_get(cpuidle_driver->owner))
+ /*
+ * This will maintain compatibility with old cpuidle_device
+ * structure where driver pointer is not set.
+ *
+ * To Do: Change all call sites to set dev->drv pointer.
+ * This can be changed to BUG() later in case somebody
+ * registers without a driver pointer.
+ */
+ if (!dev->drv)
+ dev->drv = cpuidle_driver;
+ if (!try_module_get(dev->drv->owner))
return -EINVAL;

init_completion(&dev->kobj_unregister);
@@ -313,10 +330,11 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
dev->states[i].power_usage = -1 - i;
}

- per_cpu(cpuidle_devices, dev->cpu) = dev;
+ if (cpuidle_driver == dev->drv)
+ per_cpu(cpuidle_devices, dev->cpu) = dev;
list_add(&dev->device_list, &cpuidle_detected_devices);
if ((ret = cpuidle_add_sysfs(sys_dev))) {
- module_put(cpuidle_driver->owner);
+ module_put(dev->drv->owner);
return ret;
}

@@ -367,13 +385,13 @@ void cpuidle_unregister_device(struct cpuidle_device *dev)
cpuidle_disable_device(dev);

cpuidle_remove_sysfs(sys_dev);
- list_del(&dev->device_list);
wait_for_completion(&dev->kobj_unregister);
- per_cpu(cpuidle_devices, dev->cpu) = NULL;
+ if (cpuidle_driver == dev->drv)
+ per_cpu(cpuidle_devices, dev->cpu) = NULL;

cpuidle_resume_and_unlock();

- module_put(cpuidle_driver->owner);
+ module_put(dev->drv->owner);
}

EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
@@ -413,6 +431,15 @@ static inline void latency_notifier_init(struct notifier_block *n)

#endif /* CONFIG_SMP */

+#ifdef CONFIG_ARCH_USES_PMIDLE
+static inline void save_pm_idle(void)
+{
+ pm_idle_old = pm_idle;
+}
+#else
+static inline void save_pm_idle(void) {}
+#endif
+
/**
* cpuidle_init - core initializer
*/
@@ -420,7 +447,7 @@ static int __init cpuidle_init(void)
{
int ret;

- pm_idle_old = pm_idle;
+ save_pm_idle();

ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
if (ret)
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index fd1601e..c235286 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -14,8 +14,83 @@

#include "cpuidle.h"

+#define MAX_PRIORITY 1000
+#define DEFAULT_PRIORITY 100
+
static struct cpuidle_driver *cpuidle_curr_driver;
DEFINE_SPINLOCK(cpuidle_driver_lock);
+LIST_HEAD(registered_cpuidle_drivers);
+
+static struct cpuidle_driver *select_cpuidle_driver(void)
+{
+ struct cpuidle_driver *item = NULL, *selected = NULL;
+ unsigned int min_priority = MAX_PRIORITY;
+
+ list_for_each_entry(item, &registered_cpuidle_drivers,
+ driver_list) {
+ if (item->priority <= min_priority) {
+ selected = item;
+ min_priority = item->priority;
+ }
+ }
+ return selected;
+}
+
+static void set_current_cpuidle_driver(struct cpuidle_driver *drv)
+{
+ struct cpuidle_device *item = NULL;
+ if (drv == cpuidle_curr_driver)
+ return;
+
+ /* Unregister the previous drivers devices */
+ /* Do we need to take cpuidle_lock ? {un}register_device takes lock*/
+ if (cpuidle_curr_driver) {
+ list_for_each_entry(item, &cpuidle_detected_devices,
+ device_list) {
+ if (item->drv == cpuidle_curr_driver)
+ cpuidle_unregister_device(item);
+ }
+ }
+
+ cpuidle_curr_driver = drv;
+
+ if (drv == NULL)
+ return;
+ else {
+ /* Register the new driver devices */
+ list_for_each_entry(item, &cpuidle_detected_devices,
+ device_list) {
+ if (item->drv == drv)
+ cpuidle_register_device(item);
+ }
+ }
+}
+
+static inline int arch_allow_register(void)
+{
+#ifdef CONFIG_ARCH_USES_PMIDLE
+ if (cpuidle_curr_driver)
+ return -EPERM;
+ else
+ return 0;
+#else
+ return 0;
+#endif
+}
+
+static inline int arch_allow_unregister(struct cpuidle_driver *drv)
+{
+#ifdef CONFIG_ARCH_USES_PMIDLE
+ if (drv != cpuidle_curr_driver) {
+ WARN(1, "invalid cpuidle_unregister_driver(%s)\n",
+ drv->name);
+ return -EPERM;
+ } else
+ return 0;
+#else
+ return 0;
+#endif
+}

/**
* cpuidle_register_driver - registers a driver
@@ -23,15 +98,29 @@ DEFINE_SPINLOCK(cpuidle_driver_lock);
*/
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
+ struct cpuidle_driver *item = NULL;
if (!drv)
return -EINVAL;
+ if (drv->priority == 0)
+ drv->priority = DEFAULT_PRIORITY;

spin_lock(&cpuidle_driver_lock);
- if (cpuidle_curr_driver) {
+
+ if (arch_allow_register()) {
spin_unlock(&cpuidle_driver_lock);
return -EBUSY;
}
- cpuidle_curr_driver = drv;
+
+ /* Check if driver already registered */
+ list_for_each_entry(item, &registered_cpuidle_drivers, driver_list) {
+ if (item == drv) {
+ spin_unlock(&cpuidle_driver_lock);
+ return -EINVAL;
+ }
+ }
+
+ list_add(&drv->driver_list, &registered_cpuidle_drivers);
+ set_current_cpuidle_driver(select_cpuidle_driver());
spin_unlock(&cpuidle_driver_lock);

return 0;
@@ -54,14 +143,25 @@ EXPORT_SYMBOL_GPL(cpuidle_get_driver);
*/
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
- if (drv != cpuidle_curr_driver) {
- WARN(1, "invalid cpuidle_unregister_driver(%s)\n",
- drv->name);
+ struct cpuidle_device *item = NULL;
+
+ if (arch_allow_unregister(drv))
return;
- }

spin_lock(&cpuidle_driver_lock);
- cpuidle_curr_driver = NULL;
+
+ /* Set some other driver as current */
+ list_del(&drv->driver_list);
+ set_current_cpuidle_driver(select_cpuidle_driver());
+
+ /* Delete all devices corresponding to this driver */
+ mutex_lock(&cpuidle_lock);
+ list_for_each_entry(item, &cpuidle_detected_devices, device_list) {
+ if (item->drv == drv)
+ list_del(&item->device_list);
+ }
+ mutex_unlock(&cpuidle_lock);
+
spin_unlock(&cpuidle_driver_lock);
}

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 1be416b..cbb504c 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -96,6 +96,7 @@ struct cpuidle_device {
struct cpuidle_state *last_state;

struct list_head device_list;
+ struct cpuidle_driver *drv;
struct kobject kobj;
struct completion kobj_unregister;
void *governor_data;
@@ -125,6 +126,8 @@ static inline int cpuidle_get_last_residency(struct cpuidle_device *dev)
struct cpuidle_driver {
char name[CPUIDLE_NAME_LEN];
struct module *owner;
+ unsigned int priority;
+ struct list_head driver_list;
};

#ifdef CONFIG_CPU_IDLE


\
 
 \ /
  Last update: 2011-02-08 11:55    [from the cache]
©2003-2011 Jasper Spaans