v4.19.13 snapshot.
diff --git a/include/linux/win_minmax.h b/include/linux/win_minmax.h
new file mode 100644
index 0000000..4ca2842
--- /dev/null
+++ b/include/linux/win_minmax.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/**
+ * lib/minmax.c: windowed min/max tracker by Kathleen Nichols.
+ *
+ */
+#ifndef MINMAX_H
+#define MINMAX_H
+
+#include <linux/types.h>
+
+/* A single data point for our parameterized min-max tracker */
+struct minmax_sample {
+ u32 t; /* time measurement was taken */
+ u32 v; /* value measured */
+};
+
+/* State for the parameterized min-max tracker */
+struct minmax {
+ struct minmax_sample s[3];
+};
+
+static inline u32 minmax_get(const struct minmax *m)
+{
+ return m->s[0].v;
+}
+
+static inline u32 minmax_reset(struct minmax *m, u32 t, u32 meas)
+{
+ struct minmax_sample val = { .t = t, .v = meas };
+
+ m->s[2] = m->s[1] = m->s[0] = val;
+ return m->s[0].v;
+}
+
+u32 minmax_running_max(struct minmax *m, u32 win, u32 t, u32 meas);
+u32 minmax_running_min(struct minmax *m, u32 win, u32 t, u32 meas);
+
+#endif