79 lines
3.3 KiB
C
79 lines
3.3 KiB
C
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/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef __IICMUX_H
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#define __IICMUX_H
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#define IICMUX_MAX_BUSES 16 /* More than any available mux chip. */
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/*
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* IICMUX_SELECT_IDLE instructs the mux hardware driver to do whatever it is
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* configured to do when the downstream buses are idle. Hardware has varying
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* capabilities; it may disconnect all downstream buses, or connect a specific
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* bus, or just leave whatever bus was last used connected. Hardware which is
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* capable of various choices will have some mechanism to configure the choice
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* which is handled outside of the iicmux framework.
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*/
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#define IICMUX_SELECT_IDLE (-1)
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/*
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* The iicmux softc; chip drivers should embed one of these as the first member
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* variable of their own softc struct, and must call iicmux_attach() to
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* initialize it before calling any other iicmux functions.
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*/
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struct iicmux_softc {
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device_t busdev; /* Upstream i2c bus (may not be our parent). */
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device_t dev; /* Ourself. */
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int maxbus; /* Index of highest populated busdevs slot. */
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int numbuses; /* Number of buses supported by the chip. */
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int debugmux; /* Write debug messages when > 0. */
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device_t childdevs[IICMUX_MAX_BUSES]; /* Child bus instances. */
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#ifdef FDT
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phandle_t childnodes[IICMUX_MAX_BUSES]; /* Child bus fdt nodes. */
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#endif
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};
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DECLARE_CLASS(iicmux_driver);
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/*
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* Helpers to call from attach/detach functions of chip-specific drivers.
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*
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* The iicmux_attach() function initializes the core driver's portion of the
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* softc, and creates child iicbus instances for any children it can identify
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* using hints and FDT data. If a chip driver does its own device_add_child()
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* calls to add other downstream buses that participate in the mux switching, it
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* must call iicmux_add_child() to inform the core driver of the downstream
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* busidx<->device_t relationship.
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*/
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int iicmux_add_child(device_t dev, device_t child, int busidx);
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int iicmux_attach(device_t dev, device_t busdev, int numbuses);
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int iicmux_detach(device_t dev);
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#endif
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