diff --git a/include/regmap.h b/include/regmap.h
index a3afb72..8359c51 100644
--- a/include/regmap.h
+++ b/include/regmap.h
@@ -248,6 +248,8 @@
  * @cond:	Break condition (usually involving @val)
  * @sleep_us:	Maximum time to sleep between reads in us (0 tight-loops).
  * @timeout_ms:	Timeout in ms, 0 means never timeout
+ * @test_add_time: Used for sandbox testing - amount of time to add after
+ *		starting the loop (0 if not testing)
  *
  * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_read
  * error return value in case of a error read. In the two former cases,
@@ -256,8 +258,12 @@
  *
  * This is modelled after the regmap_read_poll_timeout macros in linux but
  * with millisecond timeout.
+ *
+ * The _test version is for sandbox testing only. Do not use this in normal
+ * code as it advances the timer.
  */
-#define regmap_read_poll_timeout(map, addr, val, cond, sleep_us, timeout_ms) \
+#define regmap_read_poll_timeout_test(map, addr, val, cond, sleep_us, \
+				      timeout_ms, test_add_time) \
 ({ \
 	unsigned long __start = get_timer(0); \
 	int __ret; \
@@ -267,6 +273,8 @@
 			break; \
 		if (cond) \
 			break; \
+		if (IS_ENABLED(CONFIG_SANDBOX) && test_add_time) \
+			sandbox_timer_add_offset(test_add_time); \
 		if ((timeout_ms) && get_timer(__start) > (timeout_ms)) { \
 			__ret = regmap_read((map), (addr), &(val)); \
 			break; \
@@ -277,6 +285,10 @@
 	__ret ?: ((cond) ? 0 : -ETIMEDOUT); \
 })
 
+#define regmap_read_poll_timeout(map, addr, val, cond, sleep_us, timeout_ms) \
+	regmap_read_poll_timeout_test(map, addr, val, cond, sleep_us, \
+				      timeout_ms, 0) \
+
 /**
  * regmap_update_bits() - Perform a read/modify/write using a mask
  *