sandbox: Allow reading/writing of RAM buffer

It is useful to be able to save and restore the RAM contents of sandbox
U-Boot either for setting up tests, for later analysys, or for chaining
together multiple tests which need to keep the same memory contents.

Add a function to provide a memory file for U-Boot. This is read on
start-up and written when shutting down. If the file does not exist
on start-up, it will be created when shutting down.

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

arch/sandbox/include/asm/global_data.h

@@ -12,7 +12,7 @@
 
 /* Architecture-specific global data */
 struct arch_global_data {
-	u8		*ram_buf;	/* emulated RAM buffer */
+	uint8_t		*ram_buf;	/* emulated RAM buffer */
 };
 
 #include <asm-generic/global_data.h>

arch/sandbox/include/asm/state.h

@@ -30,6 +30,10 @@ struct sandbox_state {
 	const char *parse_err;		/* Error to report from parsing */
 	int argc;			/* Program arguments */
 	char **argv;
+	uint8_t *ram_buf;		/* Emulated RAM buffer */
+	unsigned int ram_size;		/* Size of RAM buffer */
+	const char *ram_buf_fname;	/* Filename to use for RAM buffer */
+	bool write_ram_buf;		/* Write RAM buffer on exit */
 
 	/* Pointer to information for each SPI bus/cs */
 	struct sandbox_spi_info spi[CONFIG_SANDBOX_SPI_MAX_BUS]
@@ -55,4 +59,12 @@ struct sandbox_state *state_get_current(void);
  */
 int state_init(void);
 
+/**
+ * Uninitialize the test system state, writing out state if configured to
+ * do so.
+ *
+ * @return 0 if OK, -ve on error
+ */
+int state_uninit(void);
+
 #endif