sandbox: Add a way to reset sandbox state for tests

Running a new test should reset the sandbox state to avoid tests
interferring with each other. Move the existing state-reset code into a
function so it can be used from tests.

Also update the code to reset the SPI devices and adjust the test code to
call it.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/state.c

@@ -351,6 +351,16 @@ bool state_get_skip_delays(void)
 	return state->skip_delays;
 }
 
+void state_reset_for_test(struct sandbox_state *state)
+{
+	/* No reset yet, so mark it as such. Always allow power reset */
+	state->last_sysreset = SYSRESET_COUNT;
+	state->sysreset_allowed[SYSRESET_POWER] = true;
+
+	memset(&state->wdt, '\0', sizeof(state->wdt));
+	memset(state->spi, '\0', sizeof(state->spi));
+}
+
 int state_init(void)
 {
 	state = &main_state;
@@ -359,10 +369,7 @@ int state_init(void)
 	state->ram_buf = os_malloc(state->ram_size);
 	assert(state->ram_buf);
 
-	/* No reset yet, so mark it as such. Always allow power reset */
-	state->last_sysreset = SYSRESET_COUNT;
-	state->sysreset_allowed[SYSRESET_POWER] = true;
-
+	state_reset_for_test(state);
 	/*
 	 * Example of how to use GPIOs:
 	 *

arch/sandbox/include/asm/state.h

@@ -214,6 +214,13 @@ void state_set_skip_delays(bool skip_delays);
 bool state_get_skip_delays(void);
 
 /**
+ * state_reset_for_test() - Reset ready to re-run tests
+ *
+ * This clears out any test state ready for another test run.
+ */
+void state_reset_for_test(struct sandbox_state *state);
+
+/**
  * Initialize the test system state
  */
 int state_init(void);

test/dm/test-main.c

@@ -29,6 +29,7 @@ static int dm_test_init(struct unit_test_state *uts)
 	memset(dms, '\0', sizeof(*dms));
 	gd->dm_root = NULL;
 	memset(dm_testdrv_op_count, '\0', sizeof(dm_testdrv_op_count));
+	state_reset_for_test(state_get_current());
 
 	ut_assertok(dm_init(false));
 	dms->root = dm_root();