Re: [Intel-gfx] [PATCH v2 6/8] drm/i915: Add REG_GENMASK64() and REG_FIELD_GET64()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 11 Feb 2022, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> We treat SSKPD as a 64 bit register. Add the support macros
> to define/extract bits in such registers.
>
> v2: Fix 32bit builds
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/i915_reg_defs.h | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg_defs.h b/drivers/gpu/drm/i915/i915_reg_defs.h
> index 34d37bbf08cd..d78d78fce431 100644
> --- a/drivers/gpu/drm/i915/i915_reg_defs.h
> +++ b/drivers/gpu/drm/i915/i915_reg_defs.h
> @@ -37,6 +37,21 @@
>  				 __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.
> + */
> +#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)))))
> +
>  /*
>   * Local integer constant expression version of is_power_of_2().
>   */
> @@ -71,6 +86,18 @@
>   */
>  #define REG_FIELD_GET(__mask, __val)	((u32)FIELD_GET(__mask, __val))
>  
> +/**
> + * REG_FIELD_GET64() - Extract a u64 bitfield value
> + * @__mask: shifted mask defining the field's length and position
> + * @__val: value to extract the bitfield value from
> + *
> + * Local wrapper for FIELD_GET() to force u64 and for consistency with
> + * REG_GENMASK64().
> + *
> + * @return: Masked and shifted value of the field defined by @__mask in @__val.
> + */
> +#define REG_FIELD_GET64(__mask, __val)	((u64)FIELD_GET(__mask, __val))
> +
>  typedef struct {
>  	u32 reg;
>  } i915_reg_t;

-- 
Jani Nikula, Intel Open Source Graphics Center