On Mon, 22 Jul 2013, Sudeep KarkadaNagesha wrote:
> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@xxxxxxx>
>
> Currently different drivers requiring to access cpu device node are
> parsing the device tree themselves. Since the ordering in the DT need
> not match the logical cpu ordering, the parsing logic needs to consider
> that. However, this has resulted in lots of code duplication and in some
> cases even incorrect logic.
>
> It's better to consolidate them by adding support for getting cpu
> device node for a given logical cpu index in DT core library. However
> logical to physical index mapping can be architecture specific.
>
> This patch adds of_get_cpu_node to retrieve a cpu device node for a
> given logical cpu index. The default matching of the physical id to the
> logical cpu index can be overridden by architecture specific code.
>
> It is recommended to use these helper function only in pre-SMP/early
> initialisation stages to retrieve CPU device node pointers in logical
> ordering. Once the cpu devices are registered, it can be retrieved easily
> from cpu device of_node which avoids unnecessary parsing and matching.
>
> Acked-by: Rob Herring <rob.herring@xxxxxxxxxxx>
> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@xxxxxxx>
Minor nits below. Otherwise...
Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>
> ---
> drivers/of/base.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/of.h | 6 +++++
> 2 files changed, 78 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 5c54279..1e690bf 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -230,6 +230,78 @@ const void *of_get_property(const struct device_node *np, const char *name,
> }
> EXPORT_SYMBOL(of_get_property);
>
> +/*
> + * arch_match_cpu_phys_id - Match the given logical CPU and physical id
> + *
> + * @cpu: logical index of a cpu
> + * @phys_id: physical identifier of a cpu
> + *
> + * CPU logical to physical index mapping is architecture specific.
> + * However this __weak function provides a default match of physical
> + * id to logical cpu index.
> + *
> + * Returns true if the physical identifier and the logical index correspond
> + * to the same cpu, false otherwise.
> + */
> +bool __weak arch_match_cpu_phys_id(int cpu, u64 phys_id)
Maybe a prototype declaration for this function should be added to
include/linux/of.h to avoid mismatch with architecture provided
versions.
> +{
> + return (u32)phys_id == cpu;
> +}
> +
> +/**
> + * of_get_cpu_node - Get device node associated with the given logical CPU
> + *
> + * @cpu: CPU number(logical index) for which device node is required
> + *
> + * The main purpose of this function is to retrieve the device node for the
> + * given logical CPU index. It should be used to intialize the of_node in
s/intialize/initialize/
Nicolas
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