[PATCH v4] of: add functions to count number of elements in a property

[heiko@sntech.de (Heiko Stübner)]

Am Samstag, 18. Januar 2014, 09:07:30 schrieb Rob Herring:
> On Sat, Jan 18, 2014 at 6:02 AM, Heiko St?bner <heiko@sntech.de> wrote:
> > The need to know the number of array elements in a property is
> > a common pattern. To prevent duplication of open-coded implementations
> > add a helper static function that also centralises strict sanity
> > checking and DTB format details, as well as a set of wrapper functions
> > for u8, u16, u32 and u64.
> > 
> > Suggested-by: Mark Rutland <mark.rutland@arm.com>
> > Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> > ---
> 
> Looks good. Do you plan to convert some users to use this?

My plan at the moment was to "just" use it for my mmio-sram-reserve stuff - 
just wanted to make sure that this change is sane, before having to sent the 
whole thing for each iteration.

I haven't yet looked where the other users, that Mark mentioned, are at :-)


Heiko


> > changes since v3:
> > address more comments from Rob Herring
> > - export the base function and inline the type-specific wrappers
> > changes since v2:
> > address more comments from Mark Rutland
> > - switch to of_property_count_elems_of_size
> > - use full_name instead of name in error message
> > changes since v1:
> > address comments from Rob Herring and Mark Rutland:
> > - provide a helper and a set of wrappers for u8-u64
> > - get rid of extra len variable, prop->length is enough
> > - include node name in error message
> > 
> > Mark, does your Reviewed-by holds for this variant too?
> > 
> >  drivers/of/base.c  |   32 ++++++++++++++++++++++
> >  include/linux/of.h |   76
> >  ++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed,
> >  108 insertions(+)
> > 
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index f807d0e..21646c0 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -862,6 +862,38 @@ struct device_node *of_find_node_by_phandle(phandle
> > handle)> 
> >  EXPORT_SYMBOL(of_find_node_by_phandle);
> >  
> >  /**
> > 
> > + * of_property_count_elems_of_size - Count the number of elements in a
> > property + *
> > + * @np:                device node from which the property value is to be
> > read. + * @propname:  name of the property to be searched.
> > + * @elem_size: size of the individual element
> > + *
> > + * Search for a property in a device node and count the number of
> > elements of + * size elem_size in it. Returns number of elements on
> > sucess, -EINVAL if the + * property does not exist or its length does not
> > match a multiple of u16 and + * -ENODATA if the property does not have a
> > value.
> > + */
> > +int of_property_count_elems_of_size(const struct device_node *np,
> > +                               const char *propname, int elem_size)
> > +{
> > +       struct property *prop = of_find_property(np, propname, NULL);
> > +
> > +       if (!prop)
> > +               return -EINVAL;
> > +       if (!prop->value)
> > +               return -ENODATA;
> > +
> > +       if (prop->length % elem_size != 0) {
> > +               pr_err("size of %s in node %s is not a multiple of %d\n",
> > +                      propname, np->full_name, elem_size);
> > +               return -EINVAL;
> > +       }
> > +
> > +       return prop->length / elem_size;
> > +}
> > +EXPORT_SYMBOL_GPL(of_property_count_elems_of_size);
> > +
> > +/**
> > 
> >   * of_find_property_value_of_size
> >   *
> >   * @np:                device node from which the property value is to be
> >   read.> 
> > diff --git a/include/linux/of.h b/include/linux/of.h
> > index 276c546..293920d 100644
> > --- a/include/linux/of.h
> > +++ b/include/linux/of.h
> > @@ -250,6 +250,8 @@ extern struct device_node *of_find_node_with_property(
> > 
> >  extern struct property *of_find_property(const struct device_node *np,
> >  
> >                                          const char *name,
> >                                          int *lenp);
> > 
> > +extern int of_property_count_elems_of_size(const struct device_node *np,
> > +                               const char *propname, int elem_size);
> > 
> >  extern int of_property_read_u32_index(const struct device_node *np,
> >  
> >                                        const char *propname,
> >                                        u32 index, u32 *out_value);
> > 
> > @@ -426,6 +428,12 @@ static inline struct device_node
> > *of_find_compatible_node(> 
> >         return NULL;
> >  
> >  }
> > 
> > +static inline int of_property_count_elems_of_size(const struct
> > device_node *np, +                       const char *propname, int
> > elem_size)
> > +{
> > +       return -ENOSYS;
> > +}
> > +
> > 
> >  static inline int of_property_read_u32_index(const struct device_node
> >  *np,
> >  
> >                         const char *propname, u32 index, u32 *out_value)
> >  
> >  {
> > 
> > @@ -565,6 +573,74 @@ static inline int of_node_to_nid(struct device_node
> > *device) { return 0; }> 
> >  #endif
> >  
> >  /**
> > 
> > + * of_property_count_u8_elems - Count the number of u8 elements in a
> > property + *
> > + * @np:                device node from which the property value is to be
> > read. + * @propname:  name of the property to be searched.
> > + *
> > + * Search for a property in a device node and count the number of u8
> > elements + * in it. Returns number of elements on sucess, -EINVAL if the
> > property does + * not exist or its length does not match a multiple of u8
> > and -ENODATA if the + * property does not have a value.
> > + */
> > +static inline int of_property_count_u8_elems(const struct device_node
> > *np,
> > +                               const char *propname)
> > +{
> > +       return of_property_count_elems_of_size(np, propname, sizeof(u8));
> > +}
> > +
> > +/**
> > + * of_property_count_u16_elems - Count the number of u16 elements in a
> > property + *
> > + * @np:                device node from which the property value is to be
> > read. + * @propname:  name of the property to be searched.
> > + *
> > + * Search for a property in a device node and count the number of u16
> > elements + * in it. Returns number of elements on sucess, -EINVAL if the
> > property does + * not exist or its length does not match a multiple of
> > u16 and -ENODATA if the + * property does not have a value.
> > + */
> > +static inline int of_property_count_u16_elems(const struct device_node
> > *np, +                               const char *propname)
> > +{
> > +       return of_property_count_elems_of_size(np, propname, sizeof(u16));
> > +}
> > +
> > +/**
> > + * of_property_count_u32_elems - Count the number of u32 elements in a
> > property + *
> > + * @np:                device node from which the property value is to be
> > read. + * @propname:  name of the property to be searched.
> > + *
> > + * Search for a property in a device node and count the number of u32
> > elements + * in it. Returns number of elements on sucess, -EINVAL if the
> > property does + * not exist or its length does not match a multiple of
> > u32 and -ENODATA if the + * property does not have a value.
> > + */
> > +static inline int of_property_count_u32_elems(const struct device_node
> > *np, +                               const char *propname)
> > +{
> > +       return of_property_count_elems_of_size(np, propname, sizeof(u32));
> > +}
> > +
> > +/**
> > + * of_property_count_u64_elems - Count the number of u64 elements in a
> > property + *
> > + * @np:                device node from which the property value is to be
> > read. + * @propname:  name of the property to be searched.
> > + *
> > + * Search for a property in a device node and count the number of u64
> > elements + * in it. Returns number of elements on sucess, -EINVAL if the
> > property does + * not exist or its length does not match a multiple of
> > u64 and -ENODATA if the + * property does not have a value.
> > + */
> > +static inline int of_property_count_u64_elems(const struct device_node
> > *np, +                               const char *propname)
> > +{
> > +       return of_property_count_elems_of_size(np, propname, sizeof(u64));
> > +}
> > +
> > +/**
> > 
> >   * of_property_read_bool - Findfrom a property
> >   * @np:                device node from which the property value is to be
> >   read. * @propname:  name of the property to be searched.
> > 
> > --
> > 1.7.10.4