test: fuzz: Add framework for fuzzing

Add the basic infrastructure for declaring fuzz tests and a command to
invoke them.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

test/fuzz/cmd_fuzz.c

@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2022 Google, Inc.
+ * Written by Andrew Scull <ascull@google.com>
+ */
+
+#include <command.h>
+#include <common.h>
+#include <dm.h>
+#include <fuzzing_engine.h>
+#include <test/fuzz.h>
+
+static struct fuzz_test *find_fuzz_test(const char *name)
+{
+	struct fuzz_test *fuzzer = FUZZ_TEST_START();
+	size_t count = FUZZ_TEST_COUNT();
+	size_t i;
+
+	for (i = 0; i < count; ++i) {
+		if (strcmp(name, fuzzer->name) == 0)
+			return fuzzer;
+		++fuzzer;
+	}
+
+	return NULL;
+}
+
+static struct udevice *find_fuzzing_engine(void)
+{
+	struct udevice *dev;
+
+	if (uclass_first_device(UCLASS_FUZZING_ENGINE, &dev))
+		return NULL;
+
+	return dev;
+}
+
+static int do_fuzz(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+{
+	struct fuzz_test *fuzzer;
+	struct udevice *dev;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+
+	fuzzer = find_fuzz_test(argv[1]);
+	if (!fuzzer) {
+		printf("Could not find fuzzer: %s\n", argv[1]);
+		return 1;
+	}
+
+	dev = find_fuzzing_engine();
+	if (!dev) {
+		puts("No fuzzing engine available\n");
+		return 1;
+	}
+
+	while (1) {
+		const uint8_t *data;
+		size_t size;
+
+		if (dm_fuzzing_engine_get_input(dev, &data, &size)) {
+			puts("Fuzzing engine failed\n");
+			return 1;
+		}
+
+		fuzzer->func(data, size);
+	}
+
+	return 1;
+}
+
+#ifdef CONFIG_SYS_LONGHELP
+static char fuzz_help_text[] =
+	"[fuzz-test-name] - execute the named fuzz test\n"
+	;
+#endif /* CONFIG_SYS_LONGHELP */
+
+U_BOOT_CMD(
+	fuzz, CONFIG_SYS_MAXARGS, 1, do_fuzz,
+	"fuzz tests", fuzz_help_text
+);