1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2019 Ian Lepore <ian@freebsd.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #ifndef __IICMUX_H 29 #define __IICMUX_H 30 31 #define IICMUX_MAX_BUSES 16 /* More than any available mux chip. */ 32 33 /* 34 * IICMUX_SELECT_IDLE instructs the mux hardware driver to do whatever it is 35 * configured to do when the downstream buses are idle. Hardware has varying 36 * capabilities; it may disconnect all downstream buses, or connect a specific 37 * bus, or just leave whatever bus was last used connected. Hardware which is 38 * capable of various choices will have some mechanism to configure the choice 39 * which is handled outside of the iicmux framework. 40 */ 41 #define IICMUX_SELECT_IDLE (-1) 42 43 /* 44 * The iicmux softc; chip drivers should embed one of these as the first member 45 * variable of their own softc struct, and must call iicmux_attach() to 46 * initialize it before calling any other iicmux functions. 47 */ 48 struct iicmux_softc { 49 device_t busdev; /* Upstream i2c bus (may not be our parent). */ 50 device_t dev; /* Ourself. */ 51 int maxbus; /* Index of highest populated busdevs slot. */ 52 int numbuses; /* Number of buses supported by the chip. */ 53 int debugmux; /* Write debug messages when > 0. */ 54 device_t childdevs[IICMUX_MAX_BUSES]; /* Child bus instances. */ 55 #ifdef FDT 56 phandle_t childnodes[IICMUX_MAX_BUSES]; /* Child bus fdt nodes. */ 57 #endif 58 }; 59 60 DECLARE_CLASS(iicmux_driver); 61 62 /* 63 * Helpers to call from attach/detach functions of chip-specific drivers. 64 * 65 * The iicmux_attach() function initializes the core driver's portion of the 66 * softc, and creates child iicbus instances for any children it can identify 67 * using hints and FDT data. If a chip driver does its own device_add_child() 68 * calls to add other downstream buses that participate in the mux switching, it 69 * must call iicmux_add_child() to inform the core driver of the downstream 70 * busidx<->device_t relationship. 71 */ 72 int iicmux_add_child(device_t dev, device_t child, int busidx); 73 int iicmux_attach(device_t dev, device_t busdev, int numbuses); 74 int iicmux_detach(device_t dev); 75 76 #endif 77