v4.19.13 snapshot.
diff --git a/arch/arm/lib/delay-loop.S b/arch/arm/lib/delay-loop.S
new file mode 100644
index 0000000..c766694
--- /dev/null
+++ b/arch/arm/lib/delay-loop.S
@@ -0,0 +1,62 @@
+/*
+ * linux/arch/arm/lib/delay.S
+ *
+ * Copyright (C) 1995, 1996 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/delay.h>
+
+ .text
+
+.LC0: .word loops_per_jiffy
+.LC1: .word UDELAY_MULT
+
+/*
+ * loops = r0 * HZ * loops_per_jiffy / 1000000
+ *
+ * r0 <= 2000
+ * HZ <= 1000
+ */
+
+ENTRY(__loop_udelay)
+ ldr r2, .LC1
+ mul r0, r2, r0 @ r0 = delay_us * UDELAY_MULT
+ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0xfffffaf0
+ ldr r2, .LC0
+ ldr r2, [r2]
+ umull r1, r0, r2, r0 @ r0-r1 = r0 * loops_per_jiffy
+ adds r1, r1, #0xffffffff @ rounding up ...
+ adcs r0, r0, r0 @ and right shift by 31
+ reteq lr
+
+ .align 3
+
+@ Delay routine
+ENTRY(__loop_delay)
+ subs r0, r0, #1
+#if 0
+ retls lr
+ subs r0, r0, #1
+ retls lr
+ subs r0, r0, #1
+ retls lr
+ subs r0, r0, #1
+ retls lr
+ subs r0, r0, #1
+ retls lr
+ subs r0, r0, #1
+ retls lr
+ subs r0, r0, #1
+ retls lr
+ subs r0, r0, #1
+#endif
+ bhi __loop_delay
+ ret lr
+ENDPROC(__loop_udelay)
+ENDPROC(__loop_const_udelay)
+ENDPROC(__loop_delay)