u-boot/include/mailbox.h

4  * SPDX-License-Identifier: GPL-2.0
11  * A mailbox is a hardware mechanism for transferring small fixed-size messages
12  * and/or notifications between the CPU on which U-Boot runs and some other
17  * FIFOs, rather than via RAM-based buffers. The mailbox API generally
19  * leaves any higher-level protocols to other layers.
21  * A mailbox channel is a bi-directional mechanism that can send a message or
22  * notification to a single specific remote entity, and receive messages or
29  * it manages often has this capability. mailbox-uclass.h describes the
39  * struct mbox_chan - A handle to a single mailbox channel.
41  * Clients provide storage for channels. The content of the channel structure
42  * is managed solely by the mailbox API and mailbox drivers. A mailbox channel
43  * is initialized by "get"ing the mailbox. The channel struct is passed to all
47  * @id: The mailbox channel ID within the provider.
49  * Currently, the mailbox API assumes that a single integer ID is enough to
50  * identify and configure any mailbox channel for any mailbox provider. If this
61 	 * Written by of_xlate. We assume a single id is enough for now. In the
68  * mbox_get_by_index - Get/request a mailbox by integer index
70  * This looks up and requests a mailbox channel. The index is relative to the
73  * mapping of client device channel indices to provider channels may be via
74  * device-tree properties, board-provided mapping tables, or some other
78  * @index:	The index of the mailbox channel to request, within the
80  * @chan	A pointer to a channel object to initialize.
86  * mbox_get_by_name - Get/request a mailbox by name
88  * This looks up and requests a mailbox channel. The name is relative to the
91  * mapping of client device channel names to provider channels may be via
92  * device-tree properties, board-provided mapping tables, or some other
96  * @name:	The name of the mailbox channel to request, within the client's
98  * @chan	A pointer to a channel object to initialize.
105  * mbox_free - Free a previously requested mailbox channel.
107  * @chan:	A channel object that was previously successfully requested by
114  * mbox_send - Send a message over a mailbox channel
119  * @chan:	A channel object that was previously successfully requested by
130  * mbox_recv - Receive any available message from a mailbox channel
134  * into a caller-provided buffer.
136  * @chan:	A channel object that was previously successfully requested by
143  *		micro-seconds. A value of 0 does not wait at all.
144  * @return 0 if OK, -ENODATA if no message was available, or a negative error