1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2017 Ian Lepore <ian@freebsd.org>
5 *
6 * Development sponsored by Microsemi, Inc.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD$
30 */
31
32/*
33 * Helper code to recover a hung i2c bus by bit-banging a recovery sequence.
34 */
35
36#ifndef _IICBUS_IIC_RECOVER_BUS_H_
37#define	_IICBUS_IIC_RECOVER_BUS_H_
38
39struct iicrb_pin_access {
40	void   *ctx;
41	int   (*getsda)(void *ctx);
42	void  (*setsda)(void *ctx, int value);
43	int   (*getscl)(void *ctx);
44	void  (*setscl)(void *ctx, int value);
45};
46
47/*
48 * Drive the bus-recovery logic by manipulating the line states using the
49 * caller-provided functions.  This does not block or sleep or acquire any locks
50 * (unless the provided pin access functions do so).  It uses DELAY() to pace
51 * bits on the bus.
52 *
53 * Returns 0 if the bus is functioning properly or IIC_EBUSERR if the recovery
54 * attempt failed and some slave device is still driving the bus.
55 */
56int iic_recover_bus(struct iicrb_pin_access *pins);
57
58#endif
59