sandbox: Add test function to advance time

Add a function that maintains an offset to include in the system timer
values returned from the lib/time.c APIs.

This will allow timeouts to be skipped instantly in tests

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/cpu/cpu.c b/arch/sandbox/cpu/cpu.c
index 168f2ef..b6aae37 100644
--- a/arch/sandbox/cpu/cpu.c
+++ b/arch/sandbox/cpu/cpu.c
@@ -45,11 +45,6 @@
 	os_usleep(usec);
 }
 
-unsigned long __attribute__((no_instrument_function)) timer_get_us(void)
-{
-	return os_get_nsec() / 1000;
-}
-
 int cleanup_before_linux(void)
 {
 	return 0;
diff --git a/arch/sandbox/include/asm/test.h b/arch/sandbox/include/asm/test.h
index 8e490e9..296589c 100644
--- a/arch/sandbox/include/asm/test.h
+++ b/arch/sandbox/include/asm/test.h
@@ -28,4 +28,12 @@
 
 void sandbox_i2c_eeprom_set_offset_len(struct udevice *dev, int offset_len);
 
+/*
+ * sandbox_timer_add_offset()
+ *
+ * Allow tests to add to the time reported through lib/time.c functions
+ * offset: number of milliseconds to advance the system time
+ */
+void sandbox_timer_add_offset(unsigned long offset);
+
 #endif
diff --git a/board/sandbox/sandbox.c b/board/sandbox/sandbox.c
index 2227f1c..80eaa63 100644
--- a/board/sandbox/sandbox.c
+++ b/board/sandbox/sandbox.c
@@ -7,6 +7,7 @@
 #include <cros_ec.h>
 #include <dm.h>
 #include <os.h>
+#include <asm/test.h>
 #include <asm/u-boot-sandbox.h>
 
 /*
@@ -25,9 +26,17 @@
 {
 }
 
+/* system timer offset in ms */
+static unsigned long sandbox_timer_offset;
+
+void sandbox_timer_add_offset(unsigned long offset)
+{
+	sandbox_timer_offset += offset;
+}
+
 unsigned long timer_read_counter(void)
 {
-	return os_get_nsec() / 1000;
+	return os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
 }
 
 int dram_init(void)