Re: [PATCH 07/26] libfdt: Add a function to write a property placeholder

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Fri, Jan 29, 2016 at 11:23:31AM -0700, Simon Glass wrote:
> Hi David,
> 
> On 28 January 2016 at 22:29, David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org> wrote:
> > On Thu, Jan 28, 2016 at 09:39:27AM -0700, Simon Glass wrote:
> >> The existing function to add a new property to a tree being built requires
> >> that the entire contents of the new property be passed in. For some
> >> applications it is more convenient to be able to add the property contents
> >> later, perhaps by reading from a file. This avoids double-buffering of the
> >> contents.
> >>
> >> Add a new function to support this and adust the existing fdt_property() to
> >> use it.
> >>
> >> Signed-off-by: Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> >
> > So, obviously such a patch should really go towards upstream libfdt.
> >
> > I'm happy enough with the concept, but I don't like the name.
> >
> > I'd prefer fdt_property_reserve() - the idea being that it reserves
> > space for the property but doesn't fill it in.
> 
> Sounds good. I'll work up a patch. I tend to sync with upstream one a
> quarter or so.

Ok.

Actually, on further consideration, fdt_property_placeholder() is a
better name again.

> 
> >
> >> ---
> >>
> >>  include/libfdt.h    | 16 ++++++++++++++++
> >>  lib/libfdt/fdt_sw.c | 16 ++++++++++++++--
> >>  2 files changed, 30 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/include/libfdt.h b/include/libfdt.h
> >> index e48c21a..c3f37ee 100644
> >> --- a/include/libfdt.h
> >> +++ b/include/libfdt.h
> >> @@ -1181,6 +1181,22 @@ static inline int fdt_property_cell(void *fdt, const char *name, uint32_t val)
> >>  {
> >>       return fdt_property_u32(fdt, name, val);
> >>  }
> >> +
> >> +/**
> >> + * fdt_property_val - add a new property and return a pointer to its value
> >> + *
> >> + * @fdt: pointer to the device tree blob
> >> + * @name: name of property to add
> >> + * @len: length of property value in bytes
> >> + * @valp: returns a pointer to where where the value should be placed
> >> + *
> >> + * returns:
> >> + *   0, on success
> >> + *   -FDT_ERR_BADMAGIC,
> >> + *   -FDT_ERR_NOSPACE, standard meanings
> >> + */
> >> +int fdt_property_val(void *fdt, const char *name, int len, void **valp);
> >> +
> >>  #define fdt_property_string(fdt, name, str) \
> >>       fdt_property(fdt, name, str, strlen(str)+1)
> >>  int fdt_end_node(void *fdt);
> >> diff --git a/lib/libfdt/fdt_sw.c b/lib/libfdt/fdt_sw.c
> >> index 320a914..9c1df3d 100644
> >> --- a/lib/libfdt/fdt_sw.c
> >> +++ b/lib/libfdt/fdt_sw.c
> >> @@ -175,7 +175,7 @@ static int _fdt_find_add_string(void *fdt, const char *s)
> >>       return offset;
> >>  }
> >>
> >> -int fdt_property(void *fdt, const char *name, const void *val, int len)
> >> +int fdt_property_val(void *fdt, const char *name, int len, void **valp)
> >>  {
> >>       struct fdt_property *prop;
> >>       int nameoff;
> >> @@ -193,7 +193,19 @@ int fdt_property(void *fdt, const char *name, const void *val, int len)
> >>       prop->tag = cpu_to_fdt32(FDT_PROP);
> >>       prop->nameoff = cpu_to_fdt32(nameoff);
> >>       prop->len = cpu_to_fdt32(len);
> >> -     memcpy(prop->data, val, len);
> >> +     *valp = prop->data;
> >> +     return 0;
> >> +}
> >> +
> >> +int fdt_property(void *fdt, const char *name, const void *val, int len)
> >> +{
> >> +     void *ptr;
> >> +     int ret;
> >> +
> >> +     ret = fdt_property_val(fdt, name, len, &ptr);
> >> +     if (ret)
> >> +             return ret;
> >> +     memcpy(ptr, val, len);
> >>       return 0;
> >>  }
> >>
> 
> Regards,
> Simon

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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