iic_recover_bus.h revision 323419 
1/*-
2 * Copyright (c) 2017 Ian Lepore <ian@freebsd.org>
3 * All rights reserved.
4 *
5 * Development sponsored by Microsemi, Inc.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD: stable/11/sys/dev/iicbus/iic_recover_bus.h 323419 2017-09-11 02:50:24Z ian $
29 */
30
31/*
32 * Helper code to recover a hung i2c bus by bit-banging a recovery sequence.
33 */
34
35#ifndef _IICBUS_IIC_RECOVER_BUS_H_
36#define	_IICBUS_IIC_RECOVER_BUS_H_
37
38struct iicrb_pin_access {
39	void   *ctx;
40	int   (*getsda)(void *ctx);
41	void  (*setsda)(void *ctx, int value);
42	int   (*getscl)(void *ctx);
43	void  (*setscl)(void *ctx, int value);
44};
45
46/*
47 * Drive the bus-recovery logic by manipulating the line states using the
48 * caller-provided functions.  This does not block or sleep or acquire any locks
49 * (unless the provided pin access functions do so).  It uses DELAY() to pace
50 * bits on the bus.
51 *
52 * Returns 0 if the bus is functioning properly or IIC_EBUSERR if the recovery
53 * attempt failed and some slave device is still driving the bus.
54 */
55int iic_recover_bus(struct iicrb_pin_access *pins);
56
57#endif
58