+static inline s64 drm_fixp_from_fraction(s64 a, s64 b)
+{
+ s64 res;
+ bool a_neg = a < 0;
+ bool b_neg = b < 0;
+ u64 a_abs = a_neg ? -a : a;
+ u64 b_abs = b_neg ? -b : b;
+ u64 rem;
+
+ /* determine integer part */
+ u64 res_abs = div64_u64_rem(a_abs, b_abs, &rem);
+
+ /* determine fractional part */
+ {
+ u32 i = DRM_FIXED_POINT;
+
+ do {
+ rem <<= 1;
+ res_abs <<= 1;
+ if (rem >= b_abs) {
+ res_abs |= 1;
+ rem -= b_abs;
+ }
+ } while (--i != 0);
+ }
+
+ /* round up LSB */
+ {
+ u64 summand = (rem << 1) >= b_abs;
+
+ res_abs += summand;
+ }
+
+ res = (s64) res_abs;
+ if (a_neg ^ b_neg)
+ res = -res;
+ return res;
+}
+