sandbox: Add CONFIG_OF_HOSTFILE to read FDT from host file

With sandbox it is tricky to add an FDT to the image at build time (or
later) since we build an ELF file, not a plain binary, and the address
space of the whole U-Boot is not accessible in the emulated memory map
of sandbox.

Sandbox can read files directly from the host, though, so add an option
to read an FDT from a host file on start-up.

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

arch/sandbox/cpu/start.c

@@ -104,6 +104,13 @@ static int sb_cmdline_cb_command(struct sandbox_state *state, const char *arg)
 }
 SB_CMDLINE_OPT_SHORT(command, 'c', 1, "Execute U-Boot command");
 
+static int sb_cmdline_cb_fdt(struct sandbox_state *state, const char *arg)
+{
+	state->fdt_fname = arg;
+	return 0;
+}
+SB_CMDLINE_OPT_SHORT(fdt, 'd', 1, "Specify U-Boot's control FDT");
+
 int main(int argc, char *argv[])
 {
 	struct sandbox_state *state;

arch/sandbox/include/asm/state.h

@@ -34,6 +34,7 @@ enum exit_type_id {
 /* The complete state of the test system */
 struct sandbox_state {
 	const char *cmd;		/* Command to execute */
+	const char *fdt_fname;		/* Filename of FDT binary */
 	enum exit_type_id exit_type;	/* How we exited U-Boot */
 	const char *parse_err;		/* Error to report from parsing */
 	int argc;			/* Program arguments */

common/board_f.c

@@ -31,6 +31,7 @@
 #include <version.h>
 #include <environment.h>
 #include <fdtdec.h>
+#include <fs.h>
 #if defined(CONFIG_CMD_IDE)
 #include <ide.h>
 #endif
@@ -305,6 +306,55 @@ __weak int arch_cpu_init(void)
 	return 0;
 }
 
+#ifdef CONFIG_OF_HOSTFILE
+
+#define CHECK(x)		err = (x); if (err) goto failed;
+
+/* Create an empty device tree blob */
+static int make_empty_fdt(void *fdt)
+{
+	int err;
+
+	CHECK(fdt_create(fdt, 256));
+	CHECK(fdt_finish_reservemap(fdt));
+	CHECK(fdt_begin_node(fdt, ""));
+	CHECK(fdt_end_node(fdt));
+	CHECK(fdt_finish(fdt));
+
+	return 0;
+failed:
+	printf("Unable to create empty FDT: %s\n", fdt_strerror(err));
+	return -EACCES;
+}
+
+static int read_fdt_from_file(void)
+{
+	struct sandbox_state *state = state_get_current();
+	void *blob;
+	int size;
+	int err;
+
+	blob = map_sysmem(CONFIG_SYS_FDT_LOAD_ADDR, 0);
+	if (!state->fdt_fname) {
+		err = make_empty_fdt(blob);
+		if (!err)
+			goto done;
+		return err;
+	}
+	err = fs_set_blk_dev("host", NULL, FS_TYPE_SANDBOX);
+	if (err)
+		return err;
+	size = fs_read(state->fdt_fname, CONFIG_SYS_FDT_LOAD_ADDR, 0, 0);
+	if (size < 0)
+		return -EIO;
+
+done:
+	gd->fdt_blob = blob;
+
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_SANDBOX
 static int setup_ram_buf(void)
 {
@@ -328,6 +378,11 @@ static int setup_fdt(void)
 # else
 	gd->fdt_blob = (ulong *)&_end;
 # endif
+#elif defined(CONFIG_OF_HOSTFILE)
+	if (read_fdt_from_file()) {
+		puts("Failed to read control FDT\n");
+		return -1;
+	}
 #endif
 	/* Allow the early environment to override the fdt address */
 	gd->fdt_blob = (void *)getenv_ulong("fdtcontroladdr", 16,

doc/README.fdt-control

@@ -142,7 +142,11 @@ join the two:
 
 and then flash image.bin onto your board.
 
-You cannot use both of these options at the same time.
+If CONFIG_OF_HOSTFILE is defined, then it will be read from a file on
+startup. This is only useful for sandbox. Use the -d flag to U-Boot to
+specify the file to read.
+
+You cannot use more than one of these options at the same time.
 
 If you wish to put the fdt at a different address in memory, you can
 define the "fdtcontroladdr" environment variable. This is the hex

include/configs/sandbox.h

@@ -26,6 +26,7 @@
 #define CONFIG_SANDBOX_BITS_PER_LONG	64
 
 #define CONFIG_OF_CONTROL
+#define CONFIG_OF_HOSTFILE
 #define CONFIG_OF_LIBFDT
 #define CONFIG_LMB
 
@@ -71,6 +72,7 @@
 #define CONFIG_SYS_MEMTEST_START	0x00100000
 #define CONFIG_SYS_MEMTEST_END		(CONFIG_SYS_MEMTEST_START + 0x1000)
 #define CONFIG_PHYS_64BIT
+#define CONFIG_SYS_FDT_LOAD_ADDR	0x1000000
 
 /* Size of our emulated memory */
 #define CONFIG_SYS_SDRAM_BASE		0