Merge tag 'irqchip-fixes-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Pull irqchip fixes from Marc Zyngier:

  - More compatible strings for the Ingenic irqchip (introducing the
    JZ4760B SoC)
  - Select GENERIC_IRQ_MULTI_HANDLER on the ARM ep93xx platform
  - Drop all GENERIC_IRQ_MULTI_HANDLER selections from the irqchip
    Kconfig, now relying on the architecture to get it right
  - Drop the debugfs_file field from struct irq_domain, now that
    debugfs can track things on its own

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/fixp-arith.h b/include/linux/fixp-arith.h
index 8396013785ef..281cb4f83dbe 100644
--- a/include/linux/fixp-arith.h
+++ b/include/linux/fixp-arith.h
@@ -141,4 +141,23 @@ static inline s32 fixp_sin32_rad(u32 radians, u32 twopi)
 #define fixp_cos32_rad(rad, twopi)	\
 	fixp_sin32_rad(rad + twopi / 4, twopi)
 
+/**
+ * fixp_linear_interpolate() - interpolates a value from two known points
+ *
+ * @x0: x value of point 0
+ * @y0: y value of point 0
+ * @x1: x value of point 1
+ * @y1: y value of point 1
+ * @x: the linear interpolant
+ */
+static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x)
+{
+	if (y0 == y1 || x == x0)
+		return y0;
+	if (x1 == x0 || x == x1)
+		return y1;
+
+	return y0 + ((y1 - y0) * (x - x0) / (x1 - x0));
+}
+
 #endif