Re: [PATCH] libfdt: add helpers to read address and size from reg

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

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On Fri, Nov 18, 2016 at 12:05:48PM -0600, Nishanth Menon wrote:
> On 11/18/2016 11:37 AM, Benjamin Fair wrote:
> > On 11/09/2016 10:58 AM, Benjamin Fair wrote:
> > > This patch extends the capability of libfdt to parse the contents of device
> > > trees in a similar manner to fdt_address_cells and fdt_size_cells.
> > > 
> > > It adds a helper function which reads the address and size of a device from
> > > the reg property and performs basic sanity checks.
> > > 
> > > It does not perform translation to a physical address using the ranges
> > > properties of parents, but this enhancement may be added as a separate
> > > function in the future.
> > > 
> > > Signed-off-by: Benjamin Fair <b-fair-l0cyMroinI0@public.gmane.org>
> > > ---
> > > 
> > > The intent of this patch is similar to the commit "libfdt: Add helpers to read
> > > #address-cells and #size-cells" [1].
> > > 
> > > It is related to "libfdt: add address translation support" [2] but does not
> > > attempt to perform address translation and was written from scratch rather than
> > > reusing GPL code. If the issues with that patch are resolved, that
> > > functionality will complement what is added in this patch.
> > > 
> > > 
> > >  libfdt/fdt_addresses.c | 62 ++++++++++++++++++++++++++++++++++++++++++
> > >  libfdt/libfdt.h        | 29 ++++++++++++++++++++
> > >  libfdt/version.lds     |  1 +
> > >  tests/.gitignore       |  1 +
> > >  tests/Makefile.tests   |  2 +-
> > >  tests/addr_size.c      | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  tests/addresses.dts    | 11 ++++++++
> > >  tests/run_tests.sh     |  1 +
> > >  8 files changed, 180 insertions(+), 1 deletion(-)
> > >  create mode 100644 tests/addr_size.c
> 
> I think in a lot of places this simple translation of DT can easily be
> benefiting.
> 
> [1] http://www.spinics.net/lists/devicetree-compiler/msg00113.html
> [2] http://www.spinics.net/lists/devicetree-compiler/msg00093.html
> 
> Rob, David,
> 
> The motivation started off by wanting to have a better integration of libfdt
> and dt support in ATF[2] - and basic stuff is to be able to read address
> from a node - not that we could'nt do something similar as a ATF specific
> library... but common might be better for all of libfdt users, no?
> 
> Do you folks have a suggestion as to what might be a better direction to
> take here?

Sorry, I don't really follow what the question is.

> 
> Original patch for reference (since my google-fu failed to be able to find a
> devicetree-compiler patchworks)[1]:
> 
> [1] http://www.spinics.net/lists/devicetree-compiler/msg00844.html
> [2] https://github.com/ARM-software/arm-trusted-firmware/pull/747#issuecomment-259727132

-- 
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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