dmaengine: ti: Add support for k3 event routers

In k3 architecture a DMA channel (in TR momde) can be triggered by global
events, origination from different modules.

The events for triggers can be sent from any module which is connected to
PSI-L fabric, but the event number to be sent is DMA channel specific, it
is only known after the channel itself is requested.

The router operation needs to be split up:
- route_allocate: configure the dma_spec for the DMA and store the
configuration which is needed for the router's input
- set_event: callback used by the DMA driver to set the event number for
the channel and enable the routing

Signed-off-by: Peter Ujfalusi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

include/linux/dma/k3-event-router.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  Copyright (C) 2020 Texas Instruments Incorporated - https://www.ti.com
+ */
+
+#ifndef K3_EVENT_ROUTER_
+#define K3_EVENT_ROUTER_
+
+#include <linux/types.h>
+
+struct k3_event_route_data {
+	void *priv;
+	int (*set_event)(void *priv, u32 event);
+};
+
+#endif /* K3_EVENT_ROUTER_ */