lib: utils: Add simple FDT based CPPC driver framework

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

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

lib/utils/Kconfig

@@ -2,6 +2,8 @@
 
 menu "Utils and Drivers Support"
 
+source "$(OPENSBI_SRC_DIR)/lib/utils/cppc/Kconfig"
+
 source "$(OPENSBI_SRC_DIR)/lib/utils/fdt/Kconfig"
 
 source "$(OPENSBI_SRC_DIR)/lib/utils/gpio/Kconfig"

lib/utils/cppc/Kconfig

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

lib/utils/cppc/fdt_cppc.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/cppc/fdt_cppc.h>
+
+/* List of FDT CPPC drivers generated at compile time */
+extern const struct fdt_driver *const fdt_cppc_drivers[];
+
+void fdt_cppc_init(const void *fdt)
+{
+	/*
+	 * Platforms might have multiple CPPC devices or might
+	 * not have any so probe all and don't fail.
+	 */
+	fdt_driver_init_all(fdt, fdt_cppc_drivers);
+}

lib/utils/cppc/fdt_cppc_drivers.carray

@@ -0,0 +1,3 @@
+HEADER: sbi_utils/cppc/fdt_cppc.h
+TYPE: const struct fdt_driver
+NAME: fdt_cppc_drivers

lib/utils/cppc/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-$(CONFIG_FDT_CPPC) += cppc/fdt_cppc.o
+libsbiutils-objs-$(CONFIG_FDT_CPPC) += cppc/fdt_cppc_drivers.carray.o