Re: [PATCH 3/3] drm/i915: Convert REG_GENMASK* to fixed-width GENMASK_*

[Jani Nikula]

On Tue, 23 Jan 2024, Lucas De Marchi <lucas.demarchi@xxxxxxxxx> wrote:
> Now that include/linux/bits.h implements fixed-width GENMASK_*, use them
> to implement the i915/xe specific macros. Converting each driver to use
> the generic macros are left for later, when/if other driver-specific
> macros are also generalized.

With the type-specific max checks added to GENMASK_*, this would be
great.

BR,
Jani.

>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/i915_reg_defs.h | 108 +++------------------------
>  1 file changed, 11 insertions(+), 97 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h b/drivers/gpu/drm/i915/i915_reg_defs.h
> index a685db1e815d..52f99eb96f86 100644
> --- a/drivers/gpu/drm/i915/i915_reg_defs.h
> +++ b/drivers/gpu/drm/i915/i915_reg_defs.h
> @@ -9,76 +9,19 @@
>  #include <linux/bitfield.h>
>  #include <linux/bits.h>
>  
> -/**
> - * REG_BIT() - Prepare a u32 bit value
> - * @__n: 0-based bit number
> - *
> - * Local wrapper for BIT() to force u32, with compile time checks.
> - *
> - * @return: Value with bit @__n set.
> - */
> -#define REG_BIT(__n)							\
> -	((u32)(BIT(__n) +						\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&		\
> -				 ((__n) < 0 || (__n) > 31))))
> -
> -/**
> - * REG_BIT8() - Prepare a u8 bit value
> - * @__n: 0-based bit number
> - *
> - * Local wrapper for BIT() to force u8, with compile time checks.
> - *
> - * @return: Value with bit @__n set.
> - */
> -#define REG_BIT8(__n)                                                   \
> -	((u8)(BIT(__n) +                                                \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&         \
> -				 ((__n) < 0 || (__n) > 7))))
> -
> -/**
> - * REG_GENMASK() - Prepare a continuous u32 bitmask
> - * @__high: 0-based high bit
> - * @__low: 0-based low bit
> - *
> - * Local wrapper for GENMASK() to force u32, with compile time checks.
> - *
> - * @return: Continuous bitmask from @__high to @__low, inclusive.
> - */
> -#define REG_GENMASK(__high, __low)					\
> -	((u32)(GENMASK(__high, __low) +					\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&	\
> -				 __is_constexpr(__low) &&		\
> -				 ((__low) < 0 || (__high) > 31 || (__low) > (__high)))))
> -
> -/**
> - * REG_GENMASK64() - Prepare a continuous u64 bitmask
> - * @__high: 0-based high bit
> - * @__low: 0-based low bit
> - *
> - * Local wrapper for GENMASK_ULL() to force u64, with compile time checks.
> - *
> - * @return: Continuous bitmask from @__high to @__low, inclusive.
> +/*
> + * Wrappers over the generic BIT_* and GENMASK_* implementations,
> + * for compatibility reasons with previous implementation
>   */
> -#define REG_GENMASK64(__high, __low)					\
> -	((u64)(GENMASK_ULL(__high, __low) +				\
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&		\
> -				 __is_constexpr(__low) &&		\
> -				 ((__low) < 0 || (__high) > 63 || (__low) > (__high)))))
> +#define REG_GENMASK(__high, __low)	GENMASK_U32(__high, __low)
> +#define REG_GENMASK64(__high, __low)	GENMASK_U64(__high, __low)
> +#define REG_GENMASK16(__high, __low)	GENMASK_U16(__high, __low)
> +#define REG_GENMASK8(__high, __low)	GENMASK_U8(__high, __low)
>  
> -/**
> - * REG_GENMASK8() - Prepare a continuous u8 bitmask
> - * @__high: 0-based high bit
> - * @__low: 0-based low bit
> - *
> - * Local wrapper for GENMASK() to force u8, with compile time checks.
> - *
> - * @return: Continuous bitmask from @__high to @__low, inclusive.
> - */
> -#define REG_GENMASK8(__high, __low)                                     \
> -	((u8)(GENMASK(__high, __low) +                                  \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&      \
> -				 __is_constexpr(__low) &&               \
> -				 ((__low) < 0 || (__high) > 7 || (__low) > (__high)))))
> +#define REG_BIT(__n)			BIT_U32(__n)
> +#define REG_BIT64(__n)			BIT_U64(__n)
> +#define REG_BIT16(__n)			BIT_U16(__n)
> +#define REG_BIT8(__n)			BIT_U8(__n)
>  
>  /*
>   * Local integer constant expression version of is_power_of_2().
> @@ -143,35 +86,6 @@
>   */
>  #define REG_FIELD_GET64(__mask, __val)	((u64)FIELD_GET(__mask, __val))
>  
> -/**
> - * REG_BIT16() - Prepare a u16 bit value
> - * @__n: 0-based bit number
> - *
> - * Local wrapper for BIT() to force u16, with compile time
> - * checks.
> - *
> - * @return: Value with bit @__n set.
> - */
> -#define REG_BIT16(__n)                                                   \
> -	((u16)(BIT(__n) +                                                \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__n) &&         \
> -				 ((__n) < 0 || (__n) > 15))))
> -
> -/**
> - * REG_GENMASK16() - Prepare a continuous u8 bitmask
> - * @__high: 0-based high bit
> - * @__low: 0-based low bit
> - *
> - * Local wrapper for GENMASK() to force u16, with compile time
> - * checks.
> - *
> - * @return: Continuous bitmask from @__high to @__low, inclusive.
> - */
> -#define REG_GENMASK16(__high, __low)                                     \
> -	((u16)(GENMASK(__high, __low) +                                  \
> -	       BUILD_BUG_ON_ZERO(__is_constexpr(__high) &&      \
> -				 __is_constexpr(__low) &&               \
> -				 ((__low) < 0 || (__high) > 15 || (__low) > (__high)))))
>  
>  /**
>   * REG_FIELD_PREP16() - Prepare a u16 bitfield value

-- 
Jani Nikula, Intel