interrupt_controller: Add GICv3 ITS API

Add driver API for the Interrupt Translation Service GICv3 module.

The Interrupt Translation Service (ITS) translates an input EventID
from a device, identified by its DeviceID, and determines the
corresponding INTID for this input and target Redistributor + target
PE for that INTID to be delivered as LPI interrupt.

The API permits :
- allocating a new unique LPI interrupt number
- initializing support for a new DeviceID and the required EventIDs
- mapping a DeviceID + EventID to a LPI interrupt number
- triggering an LPI with a DeviceID + EventID

This API will be used by the PCIe MSI/MSI-X logic in another patchset.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

include/drivers/interrupt_controller/gicv3_its.h

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2021 BayLibre, SAS
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ * @brief Driver for ARM Generic Interrupt Controller V3 Interrupt Translation Service
+ *
+ * The Generic Interrupt Controller (GIC) Interrupt Translation Service translates an input
+ * EventID from a device, identified by its DeviceID, determines a corresponding INTID for
+ * this input and the target Redistributor and, through this, the target PE for that INTID.
+ */
+
+#ifndef ZEPHYR_INCLUDE_DRIVERS_GICV3_ITS_H_
+#define ZEPHYR_INCLUDE_DRIVERS_GICV3_ITS_H_
+
+typedef unsigned int (*its_api_alloc_intid_t)(const struct device *dev);
+typedef int (*its_api_setup_deviceid_t)(const struct device *dev, uint32_t device_id,
+					unsigned int nites);
+typedef int (*its_api_map_intid_t)(const struct device *dev, uint32_t device_id,
+				   uint32_t event_id, unsigned int intid);
+typedef int (*its_api_send_int_t)(const struct device *dev, uint32_t device_id, uint32_t event_id);
+
+__subsystem struct its_driver_api {
+	its_api_alloc_intid_t alloc_intid;
+	its_api_setup_deviceid_t setup_deviceid;
+	its_api_map_intid_t map_intid;
+	its_api_send_int_t send_int;
+};
+
+static inline int its_alloc_intid(const struct device *dev)
+{
+	const struct its_driver_api *api =
+		(const struct its_driver_api *)dev->api;
+
+	return api->alloc_intid(dev);
+}
+
+static inline int its_setup_deviceid(const struct device *dev, uint32_t device_id,
+				     unsigned int nites)
+{
+	const struct its_driver_api *api =
+		(const struct its_driver_api *)dev->api;
+
+	return api->setup_deviceid(dev, device_id, nites);
+}
+
+static inline int its_map_intid(const struct device *dev, uint32_t device_id,
+				uint32_t event_id, unsigned int intid)
+{
+	const struct its_driver_api *api =
+		(const struct its_driver_api *)dev->api;
+
+	return api->map_intid(dev, device_id, event_id, intid);
+}
+
+static inline int its_send_int(const struct device *dev, uint32_t device_id, uint32_t event_id)
+{
+	const struct its_driver_api *api =
+		(const struct its_driver_api *)dev->api;
+
+	return api->send_int(dev, device_id, event_id);
+}
+
+#endif /* ZEPHYR_INCLUDE_DRIVERS_GICV3_ITS_H_ */