GSoC: Porting OFW to RTEMS

[Christian Mauderer]

Hello Niteesh,

On 26/05/2020 19:56, Christian Mauderer wrote:
> Hello Niteesh,
> 
> On 25/05/2020 11:20, Niteesh G. S. wrote:
>> Hello,
>>
>> I have completed the porting of the OFW code from FreeBSD to RTEMS.
>> I do acknowledge the fact that we haven't decided on the directory for files
>> to be placed in. The previous conversation had stopped quite a while ago.
>> Christian suggested I work on the patch since that would also start the
>> conversation again and also refactoring the patch to the correct directory
>> will not be much of work.
>>
>> cpukit/libfreebsd was suggested as one of the directories to place the
>> ported
>> FreeBSD files. It is suggested to place all the source files under this
>> directory.
>> Since this will make the sync part easier. But this causes issues when
>> porting
>> BSP dependent files. Since RTEMS currently doesn't allow files in cpukit to
>> reference bsp headers. I faced a similar issue during my porting process
>> also.
>> The OFW init function require bsp_fdt_get function to get a reference to
>> the fdt
>> blob. But I can't include the bsp/fdt.h header file from a source file
>> under cpukit.
>> We must decide the directory quickly because my project will import other
>> FreeBSD sources like the pinmux driver for beaglebone into RTEMS.
> 
> Do you have a suggestion for another directory?
> 
> If cpukit makes problems (which it clearly does due to the BSP
> dependencies) maybe something in bsps/shared?
> 
>>
>> https://github.com/gs-niteesh/rtems/commits/ofw_branch
> 
> For small patches it would be better to send them to the list using "git
> send-email". That allows to comment directly on the patches. But in this
> case using a repo is OK because especially the import is quite big.
> 
> I'll add comments for small stuff directly on github. I hope that works ;-)

Finished adding comments for small stuff. Some bigger questions:

- How do you plan to include ofw_if.h in some driver files? RTEMS
currently puts every file that can be included with <some.h> into a path
called "include".

- You created quite some commits. I would suggest to merge all porting
commits so that you have one import commit, one port commit and maybe
one commit adding RTEMS specific files.

- You have at least one completely hand written file (ofw_if.h). Maybe
we should think about whether that is located well in the same directory
as the imported code or whether a similar structure like used in libbsd
would be better. One tree for imported files and one for RTEMS specific
hand written ones.

Please see all comments as advises. Feel free to argue against any of
them if you think different ;-)

Best regards

Christian

> 
> Best regards
> 
> Christian
> 
>> Please have a look at the last 6 patches for the ported work.
>> Below is a short summary of the patch.
>> * The openfirm.h is the OF interface that will provided to the user.
>> * The openfirm.c contains the function definition for openfirm.h. The
>> functions
>> call the respective OFW_* functions which are responsible for choosing
>> the correct implementation for OF interface.
>> * ofw_if.h is the replacement for ofw_if.h in FreeBSD. This is an auto
>> generated
>> header in FreeBSD which choose the correct OF implementation(ofw_fdt,
>> ofw_std,
>> ofw_32bit, ofw_real). In RTEMS we directly map to the FDT implementation as
>> suggested by Sebastian.
>> * ofw_fdt.c contains the fdt implementation of OF interface.
>>
>> Thanks,
>> Niteesh.
>>
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