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

[Nishanth Menon <nm-l0cyMroinI0@public.gmane.org>]

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?

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
-- 
Regards,
Nishanth Menon