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[PATCH v3 2/6] of: Add helper for mapping device node to logical CPU number

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  [PATCH v3 2/6] of: Add helper for mapping device node to logical CPU number Suzuki K Poulose <suzuki.poulose@arm.com> - 2017-07-27 17:20 +0200
    Re: [PATCH v3 2/6] of: Add helper for mapping device node to logical  CPU number Rob Herring <robh+dt@kernel.org> - 2017-07-27 17:50 +0200
      Re: [PATCH v3 2/6] of: Add helper for mapping device node to logical  CPU number Suzuki K Poulose <Suzuki.Poulose@arm.com> - 2017-07-27 18:30 +0200

#1698082 — [PATCH v3 2/6] of: Add helper for mapping device node to logical CPU number

Add a helper to map a device node to a logical CPU number to avoid
duplication. Currently this is open coded in different places (e.g
gic-v3, coresight). The helper tries to map device node to a "possible"
logical CPU id, which may not be online yet. It is the responsibility
of the user to make sure that the CPU is online. The helper uses
of_get_cpu_node() which uses arch specific backends to match the phyiscal
ids.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 drivers/of/base.c         | 26 ++++++++++++++++++++++++++
 include/linux/of_device.h |  7 +++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 686628d..0b01515 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -420,6 +420,32 @@ struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
 EXPORT_SYMBOL(of_get_cpu_node);
 
 /**
+ * of_device_node_get_cpu: Get the logical CPU number for a given device_node
+ *
+ * @cpu_node: Pointer to the device_node for CPU.
+ *
+ * Returns the logical CPU number of the given CPU device_node.
+ * Returns >= nr_cpu_ids if CPU is not found.
+ */
+int of_device_node_get_cpu(struct device_node *cpu_node)
+{
+	int cpu;
+	bool found = false;
+	struct device_node *np;
+
+	for_each_possible_cpu(cpu) {
+		np = of_get_cpu_node(cpu, NULL);
+		found = (cpu_node == np);
+		of_node_put(np);
+		if (found)
+			break;
+	}
+
+	return cpu;
+}
+EXPORT_SYMBOL(of_device_node_get_cpu);
+
+/**
  * __of_device_is_compatible() - Check if the node matches given constraints
  * @device: pointer to node
  * @compat: required compatible string, NULL or "" for any match
diff --git a/include/linux/of_device.h b/include/linux/of_device.h
index b4ad8b4..00a4ba9 100644
--- a/include/linux/of_device.h
+++ b/include/linux/of_device.h
@@ -40,6 +40,8 @@ extern int of_device_request_module(struct device *dev);
 extern void of_device_uevent(struct device *dev, struct kobj_uevent_env *env);
 extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env);
 
+extern int of_device_node_get_cpu(struct device_node *np);
+
 static inline void of_device_node_put(struct device *dev)
 {
 	of_node_put(dev->of_node);
@@ -110,6 +112,11 @@ static inline int of_dma_configure(struct device *dev, struct device_node *np)
 }
 static inline void of_dma_deconfigure(struct device *dev)
 {}
+
+static inline int of_device_node_get_cpu(struct device_node *np)
+{
+	return nr_cpu_ids;
+}
 #endif /* CONFIG_OF */
 
 #endif /* _LINUX_OF_DEVICE_H */
-- 
2.7.5

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#1698117 — Re: [PATCH v3 2/6] of: Add helper for mapping device node to logical CPU number

Please use get_maintainers and cc the right people/lists.

+Frank, DT list

On Thu, Jul 27, 2017 at 10:10 AM, Suzuki K Poulose
<suzuki.poulose@arm.com> wrote:
> Add a helper to map a device node to a logical CPU number to avoid
> duplication. Currently this is open coded in different places (e.g
> gic-v3, coresight). The helper tries to map device node to a "possible"
> logical CPU id, which may not be online yet. It is the responsibility
> of the user to make sure that the CPU is online. The helper uses
> of_get_cpu_node() which uses arch specific backends to match the phyiscal
> ids.
>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
>  drivers/of/base.c         | 26 ++++++++++++++++++++++++++
>  include/linux/of_device.h |  7 +++++++
>  2 files changed, 33 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 686628d..0b01515 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -420,6 +420,32 @@ struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
>  EXPORT_SYMBOL(of_get_cpu_node);
>
>  /**
> + * of_device_node_get_cpu: Get the logical CPU number for a given device_node
> + *
> + * @cpu_node: Pointer to the device_node for CPU.
> + *
> + * Returns the logical CPU number of the given CPU device_node.
> + * Returns >= nr_cpu_ids if CPU is not found.

Wouldn't negative be easier to test for? Then the caller doesn't need
to know nr_cpu_ids.

> + */
> +int of_device_node_get_cpu(struct device_node *cpu_node)

of_device_* is for functions operating on struct device. So find
another name. of_cpu_node_to_id perhaps.

_get functions generally imply incrementing ref counts which you are
not doing here.

> +{
> +       int cpu;
> +       bool found = false;
> +       struct device_node *np;
> +
> +       for_each_possible_cpu(cpu) {
> +               np = of_get_cpu_node(cpu, NULL);
> +               found = (cpu_node == np);
> +               of_node_put(np);
> +               if (found)
> +                       break;
> +       }
> +
> +       return cpu;
> +}
> +EXPORT_SYMBOL(of_device_node_get_cpu);
> +
> +/**
>   * __of_device_is_compatible() - Check if the node matches given constraints
>   * @device: pointer to node
>   * @compat: required compatible string, NULL or "" for any match
> diff --git a/include/linux/of_device.h b/include/linux/of_device.h
> index b4ad8b4..00a4ba9 100644
> --- a/include/linux/of_device.h
> +++ b/include/linux/of_device.h
> @@ -40,6 +40,8 @@ extern int of_device_request_module(struct device *dev);
>  extern void of_device_uevent(struct device *dev, struct kobj_uevent_env *env);
>  extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env);
>
> +extern int of_device_node_get_cpu(struct device_node *np);
> +

Wrong place for this.

>  static inline void of_device_node_put(struct device *dev)
>  {
>         of_node_put(dev->of_node);
> @@ -110,6 +112,11 @@ static inline int of_dma_configure(struct device *dev, struct device_node *np)
>  }
>  static inline void of_dma_deconfigure(struct device *dev)
>  {}
> +
> +static inline int of_device_node_get_cpu(struct device_node *np)
> +{
> +       return nr_cpu_ids;
> +}
>  #endif /* CONFIG_OF */
>
>  #endif /* _LINUX_OF_DEVICE_H */
> --
> 2.7.5
>

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#1698165 — Re: [PATCH v3 2/6] of: Add helper for mapping device node to logical CPU number

On 27/07/17 16:48, Rob Herring wrote:
> Please use get_maintainers and cc the right people/lists.
>

Sorry about that, will fix it.

> +Frank, DT list
>
> On Thu, Jul 27, 2017 at 10:10 AM, Suzuki K Poulose
> <suzuki.poulose@arm.com> wrote:
>> Add a helper to map a device node to a logical CPU number to avoid
>> duplication. Currently this is open coded in different places (e.g
>> gic-v3, coresight). The helper tries to map device node to a "possible"
>> logical CPU id, which may not be online yet. It is the responsibility
>> of the user to make sure that the CPU is online. The helper uses
>> of_get_cpu_node() which uses arch specific backends to match the phyiscal
>> ids.
>>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Sudeep Holla <sudeep.holla@arm.com>
>> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> ---
>>  drivers/of/base.c         | 26 ++++++++++++++++++++++++++
>>  include/linux/of_device.h |  7 +++++++
>>  2 files changed, 33 insertions(+)
>>
>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>> index 686628d..0b01515 100644
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -420,6 +420,32 @@ struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
>>  EXPORT_SYMBOL(of_get_cpu_node);
>>
>>  /**
>> + * of_device_node_get_cpu: Get the logical CPU number for a given device_node
>> + *
>> + * @cpu_node: Pointer to the device_node for CPU.
>> + *
>> + * Returns the logical CPU number of the given CPU device_node.
>> + * Returns >= nr_cpu_ids if CPU is not found.
>
> Wouldn't negative be easier to test for? Then the caller doesn't need
> to know nr_cpu_ids.

I followed the conventions used by cpu_mask upon error here. But, we
could return -ENODEV upon failure here.
>
>> + */
>> +int of_device_node_get_cpu(struct device_node *cpu_node)
>
> of_device_* is for functions operating on struct device. So find
> another name. of_cpu_node_to_id perhaps.
>
> _get functions generally imply incrementing ref counts which you are
> not doing here.
>

OK, I can switch to of_cpu_node_to_id().

>> +{
>> +       int cpu;
>> +       bool found = false;
>> +       struct device_node *np;
>> +
>> +       for_each_possible_cpu(cpu) {
>> +               np = of_get_cpu_node(cpu, NULL);
>> +               found = (cpu_node == np);
>> +               of_node_put(np);
>> +               if (found)
>> +                       break;
>> +       }
>> +
>> +       return cpu;
>> +}
>> +EXPORT_SYMBOL(of_device_node_get_cpu);
>> +
>> +/**
>>   * __of_device_is_compatible() - Check if the node matches given constraints
>>   * @device: pointer to node
>>   * @compat: required compatible string, NULL or "" for any match
>> diff --git a/include/linux/of_device.h b/include/linux/of_device.h
>> index b4ad8b4..00a4ba9 100644
>> --- a/include/linux/of_device.h
>> +++ b/include/linux/of_device.h
>> @@ -40,6 +40,8 @@ extern int of_device_request_module(struct device *dev);
>>  extern void of_device_uevent(struct device *dev, struct kobj_uevent_env *env);
>>  extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env);
>>
>> +extern int of_device_node_get_cpu(struct device_node *np);
>> +
>
> Wrong place for this.
>

How about include/linux/of.h ?

Suzuki

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