lib: utils: Add simple FDT reset framework

We add simple reset framework which will select and use reset driver
based on details in FDT passed by previous booting stage.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

lib/utils/reset/fdt_reset.c

@@ -0,0 +1,55 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi/sbi_scratch.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/reset/fdt_reset.h>
+
+extern struct fdt_reset fdt_reset_sifive;
+extern struct fdt_reset fdt_reset_htif;
+
+static struct fdt_reset *reset_drivers[] = {
+	&fdt_reset_sifive,
+	&fdt_reset_htif,
+};
+
+static struct fdt_reset *current_driver = NULL;
+
+int fdt_system_reset(u32 reset_type)
+{
+	if (current_driver && current_driver->system_reset)
+		return current_driver->system_reset(reset_type);
+	return 0;
+}
+
+int fdt_reset_init(void)
+{
+	int pos, noff, rc;
+	struct fdt_reset *drv;
+	const struct fdt_match *match;
+	void *fdt = sbi_scratch_thishart_arg1_ptr();
+
+	for (pos = 0; pos < array_size(reset_drivers); pos++) {
+		drv = reset_drivers[pos];
+
+		noff = fdt_find_match(fdt, drv->match_table, &match);
+		if (noff < 0)
+			continue;
+
+		if (drv->init) {
+			rc = drv->init(fdt, noff, match);
+			if (rc)
+				return rc;
+		}
+		current_driver = drv;
+		break;
+	}
+
+	return 0;
+}