lib: utils: Add simple FDT based system suspend driver framework

The generic platform can have multiple system suspend drivers so add a
simple FDT based system suspend driver framework.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>

lib/utils/Kconfig

@@ -22,6 +22,8 @@ source "$(OPENSBI_SRC_DIR)/lib/utils/reset/Kconfig"
 
 source "$(OPENSBI_SRC_DIR)/lib/utils/serial/Kconfig"
 
+source "$(OPENSBI_SRC_DIR)/lib/utils/suspend/Kconfig"
+
 source "$(OPENSBI_SRC_DIR)/lib/utils/sys/Kconfig"
 
 source "$(OPENSBI_SRC_DIR)/lib/utils/timer/Kconfig"

lib/utils/suspend/Kconfig

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: BSD-2-Clause
+
+menu "System Suspend Support"
+
+config FDT_SUSPEND
+	bool "FDT based suspend drivers"
+	depends on FDT
+	default n
+
+endmenu

lib/utils/suspend/fdt_suspend.c

@@ -0,0 +1,22 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <apatel@ventanamicro.com>
+ */
+
+#include <sbi_utils/suspend/fdt_suspend.h>
+
+/* List of FDT suspend drivers generated at compile time */
+extern const struct fdt_driver *const fdt_suspend_drivers[];
+
+void fdt_suspend_init(const void *fdt)
+{
+	/*
+	 * Platforms might have multiple system suspend devices or
+	 * might not have any so probe all and don't fail.
+	 */
+	fdt_driver_init_all(fdt, fdt_suspend_drivers);
+}

lib/utils/suspend/fdt_suspend_drivers.carray

@@ -0,0 +1,3 @@
+HEADER: sbi_utils/suspend/fdt_suspend.h
+TYPE: const struct fdt_driver
+NAME: fdt_suspend_drivers

lib/utils/suspend/objects.mk

@@ -0,0 +1,11 @@
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+# Copyright (c) 2024 Ventana Micro Systems Inc.
+#
+# Authors:
+#   Anup Patel <apatel@ventanamicro.com>
+#
+
+libsbiutils-objs-$(CONFIG_FDT_SUSPEND) += suspend/fdt_suspend.o
+libsbiutils-objs-$(CONFIG_FDT_SUSPEND) += suspend/fdt_suspend_drivers.carray.o