utils: fdt: Add fdt helper functions to parse PMU DT nodes

The PMU DT node bindings are defined in docs/pmu_support.md
Add few fdt helper functions to parse the DT node and update the
event-counter mapping tables.

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

include/sbi_utils/fdt/fdt_pmu.h

@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: BSD-2-Clause
+/*
+ * fdt_pmu.c - Flat Device Tree PMU helper routines
+ *
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Atish Patra <atish.patra@wdc.com>
+ */
+
+#ifndef __FDT_PMU_H__
+#define __FDT_PMU_H__
+
+#include <sbi/sbi_types.h>
+
+/**
+ * Fix up the PMU node in the device tree
+ *
+ * This routine:
+ * 1. Disables opensbi specific properties from the DT
+ *
+ * It is recommended that platform support call this function in
+ * their final_init() platform operation.
+ *
+ * @param fdt device tree blob
+ */
+void fdt_pmu_fixup(void *fdt);
+
+/**
+ * Setup PMU data from device tree
+ *
+ * @param fdt device tree blob
+ *
+ * @return 0 on success and negative error code on failure
+ */
+int fdt_pmu_setup(void *fdt);
+
+/**
+ * Get the mhpmevent select value read from DT for a given event
+ * @param event_idx Event ID of the given event
+ *
+ * @return The select value read from DT or 0 if given index was not found
+ */
+uint64_t fdt_pmu_get_select_value(uint32_t event_idx);
+
+#endif