[V2,7/8] ARM: cpuidle: Register per cpuidle device

Message ID 1426704372-20406-8-git-send-email-daniel.lezcano@linaro.org
State New
Headers show

Commit Message

Daniel Lezcano March 18, 2015, 6:46 p.m.
Some architectures have some cpus which does not support idle states.

Let the underlying low level code to return -ENOSYS when it is not
possible to set an idle state.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/cpuidle/cpuidle-arm.c | 45 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

Comments

Daniel Lezcano March 19, 2015, 11:27 a.m. | #1
On 03/19/2015 12:08 PM, Lorenzo Pieralisi wrote:
> On Wed, Mar 18, 2015 at 06:46:11PM +0000, Daniel Lezcano wrote:
>> Some architectures have some cpus which does not support idle states.
>>
>> Let the underlying low level code to return -ENOSYS when it is not
>> possible to set an idle state.
>
> http://www.spinics.net/lists/linux-acpi/msg55550.html
>
> -ENXIO ?

Ack, it makes more sense.

>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
>>   drivers/cpuidle/cpuidle-arm.c | 45 +++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 43 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
>> index 1c94b88..0682ed0 100644
>> --- a/drivers/cpuidle/cpuidle-arm.c
>> +++ b/drivers/cpuidle/cpuidle-arm.c
>> @@ -17,11 +17,14 @@
>>   #include <linux/kernel.h>
>>   #include <linux/module.h>
>>   #include <linux/of.h>
>> +#include <linux/slab.h>
>>
>>   #include <asm/cpuidle.h>
>>
>>   #include "dt_idle_states.h"
>>
>> +static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
>> +
>>   /*
>>    * arm_enter_idle_state - Programs CPU to enter the specified state
>>    *
>> @@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
>>   {
>>   	int cpu, ret;
>>   	struct cpuidle_driver *drv = &arm_idle_driver;
>> +	struct cpuidle_device *dev;
>>
>>   	/*
>>   	 * Initialize idle states data, starting at index 1.
>> @@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
>>   	if (ret <= 0)
>>   		return ret ? : -ENODEV;
>>
>> +	ret = cpuidle_register_driver(drv);
>> +	if (ret) {
>> +		pr_err("Failed to register cpuidle driver\n");
>> +		return ret;
>> +	}
>> +
>>   	/*
>>   	 * Call arch CPU operations in order to initialize
>>   	 * idle states suspend back-end specific data
>>   	 */
>>   	for_each_possible_cpu(cpu) {
>>   		ret = arm_cpuidle_init(cpu);
>> +
>> +		/* This cpu does not support any idle states */
>> +		if (ret == -ENOSYS)
>> +			continue;
>> +
>>   		if (ret) {
>>   			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>> -			return ret;
>> +			goto out_fail;
>> +		}
>> +
>> +		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>> +		if (!dev) {
>> +			pr_err("Failed to allocate cpuidle device\n");
>> +			goto out_fail;
>> +		}
>> +
>> +		dev->cpu = cpu;
>> +		per_cpu(cpuidle_arm_dev, cpu) = dev;
>> +
>> +		ret = cpuidle_register_device(dev);
>> +		if (ret) {
>> +			pr_err("Failed to register cpuidle device for CPU %d\n",
>> +			       cpu);
>> +			kfree(dev);
>> +			goto out_fail;
>>   		}
>>   	}
>> +out:
>> +	return ret;
>
> return 0;
>
>>
>> -	return cpuidle_register(drv, NULL);
>> +out_fail:
>> +	for (cpu--; cpu <= 0; cpu--) {
>
> This loop is wrong.

Why is it wrong ? We have to initialize at cpu - 1 to unregister the 
previous registered cpu, not the current one, no ?

>> +		dev = per_cpu(cpuidle_arm_dev, cpu);
>> +		cpuidle_unregister_device(dev);
>> +		kfree(dev);
>> +	}
>> +	cpuidle_unregister_driver(drv);
>> +	goto out;
>
> You just:
>
> return ret;
>
> little point in jumping around to just return.

Ok.
Daniel Lezcano March 19, 2015, 11:44 a.m. | #2
On 03/19/2015 12:38 PM, Lorenzo Pieralisi wrote:
> On Thu, Mar 19, 2015 at 11:27:20AM +0000, Daniel Lezcano wrote:
>
> [...]
>
>>>>    	for_each_possible_cpu(cpu) {
>>>>    		ret = arm_cpuidle_init(cpu);
>>>> +
>>>> +		/* This cpu does not support any idle states */
>>>> +		if (ret == -ENOSYS)
>>>> +			continue;
>>>> +
>>>>    		if (ret) {
>>>>    			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>>>> -			return ret;
>>>> +			goto out_fail;
>>>> +		}
>>>> +
>>>> +		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>>>> +		if (!dev) {
>>>> +			pr_err("Failed to allocate cpuidle device\n");
>>>> +			goto out_fail;
>>>> +		}
>>>> +
>>>> +		dev->cpu = cpu;
>>>> +		per_cpu(cpuidle_arm_dev, cpu) = dev;
>>>> +
>>>> +		ret = cpuidle_register_device(dev);
>>>> +		if (ret) {
>>>> +			pr_err("Failed to register cpuidle device for CPU %d\n",
>>>> +			       cpu);
>>>> +			kfree(dev);
>>>> +			goto out_fail;
>>>>    		}
>>>>    	}
>>>> +out:
>>>> +	return ret;
>>>
>>> return 0;
>>>
>>>>
>>>> -	return cpuidle_register(drv, NULL);
>>>> +out_fail:
>>>> +	for (cpu--; cpu <= 0; cpu--) {
>>>
>>> This loop is wrong.
>>
>> Why is it wrong ? We have to initialize at cpu - 1 to unregister the
>> previous registered cpu, not the current one, no ?
>
> Yes, but on cpu>=0 not cpu<=0
>
> while (--cpu >= 0)

Ah, yes. Thanks for spotting this.

   -- Daniel
Lina Iyer March 19, 2015, 3:31 p.m. | #3
On Wed, Mar 18 2015 at 12:46 -0600, Daniel Lezcano wrote:
>Some architectures have some cpus which does not support idle states.
>
>Let the underlying low level code to return -ENOSYS when it is not
>possible to set an idle state.
>
>Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>---
> drivers/cpuidle/cpuidle-arm.c | 45 +++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 43 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
>index 1c94b88..0682ed0 100644
>--- a/drivers/cpuidle/cpuidle-arm.c
>+++ b/drivers/cpuidle/cpuidle-arm.c
>@@ -17,11 +17,14 @@
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/of.h>
>+#include <linux/slab.h>
>
> #include <asm/cpuidle.h>
>
> #include "dt_idle_states.h"
>
>+static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);

Is a per-cpu variable needed? There seems to be no per-cpu access, other
than at init.

>+
> /*
>  * arm_enter_idle_state - Programs CPU to enter the specified state
>  *
>@@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
> {
> 	int cpu, ret;
> 	struct cpuidle_driver *drv = &arm_idle_driver;
>+	struct cpuidle_device *dev;
>
> 	/*
> 	 * Initialize idle states data, starting at index 1.
>@@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
> 	if (ret <= 0)
> 		return ret ? : -ENODEV;
>
>+	ret = cpuidle_register_driver(drv);
>+	if (ret) {
>+		pr_err("Failed to register cpuidle driver\n");
>+		return ret;
>+	}
>+
> 	/*
> 	 * Call arch CPU operations in order to initialize
> 	 * idle states suspend back-end specific data
> 	 */
> 	for_each_possible_cpu(cpu) {
> 		ret = arm_cpuidle_init(cpu);
>+
>+		/* This cpu does not support any idle states */
>+		if (ret == -ENOSYS)
>+			continue;
>+
> 		if (ret) {
> 			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>-			return ret;
>+			goto out_fail;
>+		}
>+
>+		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>+		if (!dev) {
>+			pr_err("Failed to allocate cpuidle device\n");
>+			goto out_fail;
>+		}
>+
>+		dev->cpu = cpu;
>+		per_cpu(cpuidle_arm_dev, cpu) = dev;
>+
>+		ret = cpuidle_register_device(dev);
>+		if (ret) {
>+			pr_err("Failed to register cpuidle device for CPU %d\n",
>+			       cpu);
>+			kfree(dev);
>+			goto out_fail;
> 		}
> 	}
>+out:
>+	return ret;
>
>-	return cpuidle_register(drv, NULL);
>+out_fail:
>+	for (cpu--; cpu <= 0; cpu--) {
>+		dev = per_cpu(cpuidle_arm_dev, cpu);
>+		cpuidle_unregister_device(dev);
>+		kfree(dev);
>+	}
>+	cpuidle_unregister_driver(drv);
>+	goto out;
> }
> device_initcall(arm_idle_init);
>-- 
>1.9.1
>
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Daniel Lezcano March 19, 2015, 3:33 p.m. | #4
On 03/19/2015 04:31 PM, Lina Iyer wrote:
> On Wed, Mar 18 2015 at 12:46 -0600, Daniel Lezcano wrote:
>> Some architectures have some cpus which does not support idle states.
>>
>> Let the underlying low level code to return -ENOSYS when it is not
>> possible to set an idle state.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
>> drivers/cpuidle/cpuidle-arm.c | 45
>> +++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 43 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-arm.c
>> b/drivers/cpuidle/cpuidle-arm.c
>> index 1c94b88..0682ed0 100644
>> --- a/drivers/cpuidle/cpuidle-arm.c
>> +++ b/drivers/cpuidle/cpuidle-arm.c
>> @@ -17,11 +17,14 @@
>> #include <linux/kernel.h>
>> #include <linux/module.h>
>> #include <linux/of.h>
>> +#include <linux/slab.h>
>>
>> #include <asm/cpuidle.h>
>>
>> #include "dt_idle_states.h"
>>
>> +static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
>
> Is a per-cpu variable needed? There seems to be no per-cpu access, other
> than at init.

:)

Actually it is the cpuidle framework which is using the per cpu variable.

>> +
>> /*
>>  * arm_enter_idle_state - Programs CPU to enter the specified state
>>  *
>> @@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
>> {
>>     int cpu, ret;
>>     struct cpuidle_driver *drv = &arm_idle_driver;
>> +    struct cpuidle_device *dev;
>>
>>     /*
>>      * Initialize idle states data, starting at index 1.
>> @@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
>>     if (ret <= 0)
>>         return ret ? : -ENODEV;
>>
>> +    ret = cpuidle_register_driver(drv);
>> +    if (ret) {
>> +        pr_err("Failed to register cpuidle driver\n");
>> +        return ret;
>> +    }
>> +
>>     /*
>>      * Call arch CPU operations in order to initialize
>>      * idle states suspend back-end specific data
>>      */
>>     for_each_possible_cpu(cpu) {
>>         ret = arm_cpuidle_init(cpu);
>> +
>> +        /* This cpu does not support any idle states */
>> +        if (ret == -ENOSYS)
>> +            continue;
>> +
>>         if (ret) {
>>             pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>> -            return ret;
>> +            goto out_fail;
>> +        }
>> +
>> +        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>> +        if (!dev) {
>> +            pr_err("Failed to allocate cpuidle device\n");
>> +            goto out_fail;
>> +        }
>> +
>> +        dev->cpu = cpu;
>> +        per_cpu(cpuidle_arm_dev, cpu) = dev;
>> +
>> +        ret = cpuidle_register_device(dev);
>> +        if (ret) {
>> +            pr_err("Failed to register cpuidle device for CPU %d\n",
>> +                   cpu);
>> +            kfree(dev);
>> +            goto out_fail;
>>         }
>>     }
>> +out:
>> +    return ret;
>>
>> -    return cpuidle_register(drv, NULL);
>> +out_fail:
>> +    for (cpu--; cpu <= 0; cpu--) {
>> +        dev = per_cpu(cpuidle_arm_dev, cpu);
>> +        cpuidle_unregister_device(dev);
>> +        kfree(dev);
>> +    }
>> +    cpuidle_unregister_driver(drv);
>> +    goto out;
>> }
>> device_initcall(arm_idle_init);
>> --
>> 1.9.1
>>
Lina Iyer March 19, 2015, 3:42 p.m. | #5
On Thu, Mar 19 2015 at 09:33 -0600, Daniel Lezcano wrote:
>On 03/19/2015 04:31 PM, Lina Iyer wrote:
>>On Wed, Mar 18 2015 at 12:46 -0600, Daniel Lezcano wrote:
>>>Some architectures have some cpus which does not support idle states.
>>>
>>>Let the underlying low level code to return -ENOSYS when it is not
>>>possible to set an idle state.
>>>
>>>Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>>>---
>>>drivers/cpuidle/cpuidle-arm.c | 45
>>>+++++++++++++++++++++++++++++++++++++++++--
>>>1 file changed, 43 insertions(+), 2 deletions(-)
>>>
>>>diff --git a/drivers/cpuidle/cpuidle-arm.c
>>>b/drivers/cpuidle/cpuidle-arm.c
>>>index 1c94b88..0682ed0 100644
>>>--- a/drivers/cpuidle/cpuidle-arm.c
>>>+++ b/drivers/cpuidle/cpuidle-arm.c
>>>@@ -17,11 +17,14 @@
>>>#include <linux/kernel.h>
>>>#include <linux/module.h>
>>>#include <linux/of.h>
>>>+#include <linux/slab.h>
>>>
>>>#include <asm/cpuidle.h>
>>>
>>>#include "dt_idle_states.h"
>>>
>>>+static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
>>
>>Is a per-cpu variable needed? There seems to be no per-cpu access, other
>>than at init.
>
>:)
>
>Actually it is the cpuidle framework which is using the per cpu variable.
>

But this is static pointer, I can see that struct cpuidle_device * being
used by cpuidle framework.

It gets stored here?

DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);

But we dont need to save it here, for in this file, there is no per-cpu
access, other than when the registration fails.


>>>+
>>>/*
>>> * arm_enter_idle_state - Programs CPU to enter the specified state
>>> *
>>>@@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
>>>{
>>>    int cpu, ret;
>>>    struct cpuidle_driver *drv = &arm_idle_driver;
>>>+    struct cpuidle_device *dev;
>>>
>>>    /*
>>>     * Initialize idle states data, starting at index 1.
>>>@@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
>>>    if (ret <= 0)
>>>        return ret ? : -ENODEV;
>>>
>>>+    ret = cpuidle_register_driver(drv);
>>>+    if (ret) {
>>>+        pr_err("Failed to register cpuidle driver\n");
>>>+        return ret;
>>>+    }
>>>+
>>>    /*
>>>     * Call arch CPU operations in order to initialize
>>>     * idle states suspend back-end specific data
>>>     */
>>>    for_each_possible_cpu(cpu) {
>>>        ret = arm_cpuidle_init(cpu);
>>>+
>>>+        /* This cpu does not support any idle states */
>>>+        if (ret == -ENOSYS)
>>>+            continue;
>>>+
>>>        if (ret) {
>>>            pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>>>-            return ret;
>>>+            goto out_fail;
>>>+        }
>>>+
>>>+        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>>>+        if (!dev) {
>>>+            pr_err("Failed to allocate cpuidle device\n");
>>>+            goto out_fail;
>>>+        }
>>>+
>>>+        dev->cpu = cpu;
>>>+        per_cpu(cpuidle_arm_dev, cpu) = dev;
>>>+
>>>+        ret = cpuidle_register_device(dev);
>>>+        if (ret) {
>>>+            pr_err("Failed to register cpuidle device for CPU %d\n",
>>>+                   cpu);
>>>+            kfree(dev);
>>>+            goto out_fail;
>>>        }
>>>    }
>>>+out:
>>>+    return ret;
>>>
>>>-    return cpuidle_register(drv, NULL);
>>>+out_fail:
>>>+    for (cpu--; cpu <= 0; cpu--) {
>>>+        dev = per_cpu(cpuidle_arm_dev, cpu);
>>>+        cpuidle_unregister_device(dev);
>>>+        kfree(dev);
>>>+    }
>>>+    cpuidle_unregister_driver(drv);
>>>+    goto out;
>>>}
>>>device_initcall(arm_idle_init);
>>>--
>>>1.9.1
>>>
>
>
>-- 
> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
>
>Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
><http://twitter.com/#!/linaroorg> Twitter |
><http://www.linaro.org/linaro-blog/> Blog
>
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Daniel Lezcano March 19, 2015, 5:11 p.m. | #6
On 03/19/2015 04:42 PM, Lina Iyer wrote:
> On Thu, Mar 19 2015 at 09:33 -0600, Daniel Lezcano wrote:
>> On 03/19/2015 04:31 PM, Lina Iyer wrote:
>>> On Wed, Mar 18 2015 at 12:46 -0600, Daniel Lezcano wrote:
>>>> Some architectures have some cpus which does not support idle states.
>>>>
>>>> Let the underlying low level code to return -ENOSYS when it is not
>>>> possible to set an idle state.
>>>>
>>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>>>> ---
>>>> drivers/cpuidle/cpuidle-arm.c | 45
>>>> +++++++++++++++++++++++++++++++++++++++++--
>>>> 1 file changed, 43 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/cpuidle/cpuidle-arm.c
>>>> b/drivers/cpuidle/cpuidle-arm.c
>>>> index 1c94b88..0682ed0 100644
>>>> --- a/drivers/cpuidle/cpuidle-arm.c
>>>> +++ b/drivers/cpuidle/cpuidle-arm.c
>>>> @@ -17,11 +17,14 @@
>>>> #include <linux/kernel.h>
>>>> #include <linux/module.h>
>>>> #include <linux/of.h>
>>>> +#include <linux/slab.h>
>>>>
>>>> #include <asm/cpuidle.h>
>>>>
>>>> #include "dt_idle_states.h"
>>>>
>>>> +static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
>>>
>>> Is a per-cpu variable needed? There seems to be no per-cpu access, other
>>> than at init.
>>
>> :)
>>
>> Actually it is the cpuidle framework which is using the per cpu variable.
>>
>
> But this is static pointer, I can see that struct cpuidle_device * being
> used by cpuidle framework.
>
> It gets stored here?
>
> DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
>
> But we dont need to save it here, for in this file, there is no per-cpu
> access, other than when the registration fails.

Indeed, that is true. There is no need of these cpuidle variables. 
Furthermore, we can access the cpuidle_devices directly as they are 
exported in cpuidle.h.

I will fix it.

Thanks
   -- Daniel

>>>> +
>>>> /*
>>>> * arm_enter_idle_state - Programs CPU to enter the specified state
>>>> *
>>>> @@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
>>>> {
>>>>    int cpu, ret;
>>>>    struct cpuidle_driver *drv = &arm_idle_driver;
>>>> +    struct cpuidle_device *dev;
>>>>
>>>>    /*
>>>>     * Initialize idle states data, starting at index 1.
>>>> @@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
>>>>    if (ret <= 0)
>>>>        return ret ? : -ENODEV;
>>>>
>>>> +    ret = cpuidle_register_driver(drv);
>>>> +    if (ret) {
>>>> +        pr_err("Failed to register cpuidle driver\n");
>>>> +        return ret;
>>>> +    }
>>>> +
>>>>    /*
>>>>     * Call arch CPU operations in order to initialize
>>>>     * idle states suspend back-end specific data
>>>>     */
>>>>    for_each_possible_cpu(cpu) {
>>>>        ret = arm_cpuidle_init(cpu);
>>>> +
>>>> +        /* This cpu does not support any idle states */
>>>> +        if (ret == -ENOSYS)
>>>> +            continue;
>>>> +
>>>>        if (ret) {
>>>>            pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>>>> -            return ret;
>>>> +            goto out_fail;
>>>> +        }
>>>> +
>>>> +        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>>>> +        if (!dev) {
>>>> +            pr_err("Failed to allocate cpuidle device\n");
>>>> +            goto out_fail;
>>>> +        }
>>>> +
>>>> +        dev->cpu = cpu;
>>>> +        per_cpu(cpuidle_arm_dev, cpu) = dev;
>>>> +
>>>> +        ret = cpuidle_register_device(dev);
>>>> +        if (ret) {
>>>> +            pr_err("Failed to register cpuidle device for CPU %d\n",
>>>> +                   cpu);
>>>> +            kfree(dev);
>>>> +            goto out_fail;
>>>>        }
>>>>    }
>>>> +out:
>>>> +    return ret;
>>>>
>>>> -    return cpuidle_register(drv, NULL);
>>>> +out_fail:
>>>> +    for (cpu--; cpu <= 0; cpu--) {
>>>> +        dev = per_cpu(cpuidle_arm_dev, cpu);
>>>> +        cpuidle_unregister_device(dev);
>>>> +        kfree(dev);
>>>> +    }
>>>> +    cpuidle_unregister_driver(drv);
>>>> +    goto out;
>>>> }
>>>> device_initcall(arm_idle_init);
>>>> --
>>>> 1.9.1
>>>>
>>
>>
>> --
>> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
>>
>> Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
>> <http://twitter.com/#!/linaroorg> Twitter |
>> <http://www.linaro.org/linaro-blog/> Blog
>>

Patch

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 1c94b88..0682ed0 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -17,11 +17,14 @@ 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/slab.h>
 
 #include <asm/cpuidle.h>
 
 #include "dt_idle_states.h"
 
+static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
+
 /*
  * arm_enter_idle_state - Programs CPU to enter the specified state
  *
@@ -94,6 +97,7 @@  static int __init arm_idle_init(void)
 {
 	int cpu, ret;
 	struct cpuidle_driver *drv = &arm_idle_driver;
+	struct cpuidle_device *dev;
 
 	/*
 	 * Initialize idle states data, starting at index 1.
@@ -105,18 +109,55 @@  static int __init arm_idle_init(void)
 	if (ret <= 0)
 		return ret ? : -ENODEV;
 
+	ret = cpuidle_register_driver(drv);
+	if (ret) {
+		pr_err("Failed to register cpuidle driver\n");
+		return ret;
+	}
+
 	/*
 	 * Call arch CPU operations in order to initialize
 	 * idle states suspend back-end specific data
 	 */
 	for_each_possible_cpu(cpu) {
 		ret = arm_cpuidle_init(cpu);
+
+		/* This cpu does not support any idle states */
+		if (ret == -ENOSYS)
+			continue;
+
 		if (ret) {
 			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
-			return ret;
+			goto out_fail;
+		}
+
+		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+		if (!dev) {
+			pr_err("Failed to allocate cpuidle device\n");
+			goto out_fail;
+		}
+
+		dev->cpu = cpu;
+		per_cpu(cpuidle_arm_dev, cpu) = dev;
+
+		ret = cpuidle_register_device(dev);
+		if (ret) {
+			pr_err("Failed to register cpuidle device for CPU %d\n",
+			       cpu);
+			kfree(dev);
+			goto out_fail;
 		}
 	}
+out:
+	return ret;
 
-	return cpuidle_register(drv, NULL);
+out_fail:
+	for (cpu--; cpu <= 0; cpu--) {
+		dev = per_cpu(cpuidle_arm_dev, cpu);
+		cpuidle_unregister_device(dev);
+		kfree(dev);
+	}
+	cpuidle_unregister_driver(drv);
+	goto out;
 }
 device_initcall(arm_idle_init);