AArch64 support and sharing of various drivers

[Chris Johns]

On 4/9/20 12:43 pm, Joel Sherrill wrote:
> On Thu, Sep 3, 2020, 6:58 AM Christian Mauderer
> <christian.mauderer at embedded-brains.de
> <mailto:christian.mauderer at embedded-brains.de>> wrote:
> 
>     Hello Kinsey,
> 
>     On 01/09/2020 23:56, Kinsey Moore wrote:
>     > Hi,
>     >
>     > I’ve been working on proper AArch64 support for RTEMS
> 
>     That's great. It means good raspberry pi 4 support ;-)
> 
>     > (versus running
>     > 32-bit ARM RTEMS behind a bootloader or JTAG device that switches the
>     > CPU to AArch32 mode) and while the vast majority of the architecture
>     > support code is new, lives in its own aarch64 directories, and is
>     > unrelated to RTEMS’s ARM support, there are several drivers living in
>     > the ARM shared directory that are critical to AArch64 support and many
>     > more that could potentially be shared. Given the limited scope of
>     > initial bringup on Qemu, that list is currently: GICv3, GPT(timer), and
>     > PL011(uart). I don’t really see a precedent for this type of sharing
>     > other than the global bsps/shared and bsps/include directories. The
>     > global shared directories might make sense for the PL011 since it could
>     > theoretically be used by anything that supports AXI/AMBA, but the GIC
>     > and GPT drivers rely on ARM system registers to function with both
>     > AArch32 and AArch64.
>     >
>     >  
>     >
>     > In short, where should the GICv3 and GPT drivers be relocated along with
>     > their associated headers, if at all?
>     >
> 
>     I might get a similar problem with some drivers shared between some
>     PowerPC and ARM too (NXP reuses some of the Freescale PowerPC
>     peripherals in up to date ARM controllers). I think in theory we already
>     have such drivers that maybe should be shared but are copied or
>     re-implemented in multiple BSPs instead.
> 
> The Gaisler IP drivers were moved up in the tree recently also.
> 
>     One possibility might would be to add all arm/shared to the aarch64 too.
>     But that is a bit unclear
> 
> 
> shared/arm??

shared/dev/int
shared/dev/serial

?

> 
> shared/nxp

-1 , companies get taken over and change names.

> 
> Or
> 
> shared/IP/vendor?
> 
> They need to be above a single architecture to be shared across architectures.
> 

+1

> This is just SoC IP modules that are being reused.

So should be use the type and then the file names can be the part?

Chris