include/pcie: Add PTM API

This is a really simple one: one function is exposed to enable PTM
requester on a endpoint. PTM root capability will be enabled
automatically via a dedicated driver and its related DTS exposure.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

include/drivers/pcie/ptm.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2021 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+#ifndef ZEPHYR_INCLUDE_DRIVERS_PCIE_PTM_H_
+#define ZEPHYR_INCLUDE_DRIVERS_PCIE_PTM_H_
+
+#include <stddef.h>
+#include <zephyr/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Enable PTM on endpoint
+ *
+ * @param bdf the PCI(e) endpoint
+ * @return true if that was sucessful, false otherwise
+ */
+bool pcie_ptm_enable(pcie_bdf_t bdf);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_INCLUDE_DRIVERS_PCIE_PTM_H_ */