Re: [PATCH v2] xen/common: Move gic_preinit() to common code

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.10.2024 14:14, Oleksii Kurochko wrote:
> Introduce ic_preinit() in the common codebase, as it is not
> architecture-specific and can be reused by both PPC and RISC-V.
> This function identifies the node with the interrupt-controller property
> in the device tree and calls device_init() to handle architecture-specific
> initialization of the interrupt controller.
> 
> Additionally, rename gic_acpi_preinit() to ic_acpi_preinit() as it is used
> by ic_preinit(), while keeping it defined in architecture-specific as this
> part is architecture-specific. In case if CONFIG_ACPI=n a stub for
> ic_acpi_preinit() is provided. To declaration/defintion of ic_acpi_preint()
> is added `inline` to deal with the compilation issue:
>   error: 'ic_acpi_preinit' defined but not used [-Werror=unused-function]
> 
> Make minor adjustments compared to the original ARM implementation of
> gic_dt_preinit():
>  - Remove the local rc variable in gic_dt_preinit() since it is only used 
> once.
>  - Change the prefix from gic to ic to clarify that the function is not
>    specific to ARM’s GIC, making it suitable for other architectures as well.
> 
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
> ---
> Changes in v2:
>  - Revert changes connected to moving of gic_acpi_preinit() to common code as
>    it isn't really architecture indepent part.
>  - Update the commit message.
>  - Move stub of ic_acpi_preinit() to <asm-generic/device.h> for the case when
>    CONFIG_ACPI=n.
> ---
>  xen/arch/arm/gic.c               | 45 +------------------------------
>  xen/arch/arm/setup.c             |  3 ++-
>  xen/common/device.c              | 46 ++++++++++++++++++++++++++++++++
>  xen/include/asm-generic/device.h | 10 +++++++
>  4 files changed, 59 insertions(+), 45 deletions(-)

Looks largely okay to me now, with a question and a nit at the bottom. The
question is mainly to Arm folks, where the code is coming from, and DT
maintainers: Is a file named device.c really an appropriate "home" for
IC-related code? If IC is a common thing in the DT world, would such code
maybe better live under common/device-tree/?

> --- a/xen/include/asm-generic/device.h
> +++ b/xen/include/asm-generic/device.h
> @@ -127,6 +127,16 @@ __section(".adev.info") = {                              
>            \
>  
>  #endif /* CONFIG_ACPI */
>  
> +void ic_preinit(void);
> +
> +#ifdef CONFIG_ACPI
> +void ic_acpi_preinit(void);
> +#else
> +#include <xen/init.h>
> +
> +static inline void __init ic_acpi_preinit(void) { }
> +#endif

I don't think there's a need to have __init on an empty inline stub. That'll
then also eliminate the need for the extra #include.

Jan