drm/i915: Convert REG_GENMASK*() to fixed-width GENMASK_U*()

Now that include/linux/bits.h implements fixed-width GENMASK_U*(), 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.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Yury Norov <yury.norov@gmail.com>

Author: lucasdemarchi

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 fixed width BIT_U*() and GENMASK_U*()
+ * 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