drm: Add helper to extract lut from struct drm_color_lut32

Add helper to extract lut values in 32-bit precision needed by
hardware.

Signed-off-by: Alex Hung <[e-mail]>
Signed-off-by: Uma Shankar <[e-mail]>
Signed-off-by: Chaitanya Kumar Borah <[e-mail]>
Reviewed-by: Sebastian Wick <[e-mail]>
Signed-off-by: Simon Ser <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

include/drm/drm_color_mgmt.h

···
 					 (1 << 16) - 1);
 }
 
+/**
+ * drm_color_lut32_extract - clamp and round LUT entries
+ * @user_input: input value
+ * @bit_precision: number of bits the hw LUT supports
+ *
+ * Extract U0.bit_precision from a U0.32 LUT value.
+ *
+ */
+static inline u32 drm_color_lut32_extract(u32 user_input, int bit_precision)
+{
+	u64 max = (bit_precision >= 64) ? ~0ULL : (1ULL << bit_precision) - 1;
+
+	return DIV_ROUND_CLOSEST_ULL((u64)user_input * max,
+				     (1ULL << 32) - 1);
+}
+
 u64 drm_color_ctm_s31_32_to_qm_n(u64 user_input, u32 m, u32 n);
 
 void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,