Files
linux-stable-mirror/include/linux/mailbox_client.h
T
Jassi Brar 57df858a46 mailbox: add API to query available TX queue slots
Clients sometimes need to know whether the mailbox TX queue has room
before posting a new message. Rather than exposing internal queue state
through a struct field, provide a proper accessor function that returns
the number of available slots for a given channel.

This lets clients choose to back off when the queue is full instead of
hitting the -ENOBUFS error path and the misleading "Try increasing
MBOX_TX_QUEUE_LEN" warning.

Tested-by: Tanmay Shah <tanmay.shah@amd.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
2026-03-08 22:34:38 -05:00

52 lines
1.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2013-2014 Linaro Ltd.
* Author: Jassi Brar <jassisinghbrar@gmail.com>
*/
#ifndef __MAILBOX_CLIENT_H
#define __MAILBOX_CLIENT_H
#include <linux/device.h>
#include <linux/of.h>
struct mbox_chan;
/**
* struct mbox_client - User of a mailbox
* @dev: The client device
* @tx_block: If the mbox_send_message should block until data is
* transmitted.
* @tx_tout: Max block period in ms before TX is assumed failure
* @knows_txdone: If the client could run the TX state machine. Usually
* if the client receives some ACK packet for transmission.
* Unused if the controller already has TX_Done/RTR IRQ.
* @rx_callback: Atomic callback to provide client the data received
* @tx_prepare: Atomic callback to ask client to prepare the payload
* before initiating the transmission if required.
* @tx_done: Atomic callback to tell client of data transmission
*/
struct mbox_client {
struct device *dev;
bool tx_block;
unsigned long tx_tout;
bool knows_txdone;
void (*rx_callback)(struct mbox_client *cl, void *mssg);
void (*tx_prepare)(struct mbox_client *cl, void *mssg);
void (*tx_done)(struct mbox_client *cl, void *mssg, int r);
};
int mbox_bind_client(struct mbox_chan *chan, struct mbox_client *cl);
struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
const char *name);
struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index);
int mbox_send_message(struct mbox_chan *chan, void *mssg);
int mbox_flush(struct mbox_chan *chan, unsigned long timeout);
void mbox_client_txdone(struct mbox_chan *chan, int r); /* atomic */
bool mbox_client_peek_data(struct mbox_chan *chan); /* atomic */
unsigned int mbox_chan_tx_slots_available(struct mbox_chan *chan); /* atomic */
void mbox_free_channel(struct mbox_chan *chan); /* may sleep */
#endif /* __MAILBOX_CLIENT_H */