160 lines
4.5 KiB
C
160 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Based on the linux multiplexer framework
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*
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* At its core, a multiplexer (or mux), also known as a data selector, is a
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* device that selects between several analog or digital input signals and
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* forwards it to a single output line. This notion can be extended to work
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* with buses, like a I2C bus multiplexer for example.
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*
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* Copyright (C) 2017 Axentia Technologies AB
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* Author: Peter Rosin <peda@axentia.se>
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*
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* Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
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* Jean-Jacques Hiblot <jjhiblot@ti.com>
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*/
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#ifndef _MUX_H_
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#define _MUX_H_
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#include <linux/errno.h>
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#include <linux/types.h>
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struct udevice;
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struct mux_control;
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#if CONFIG_IS_ENABLED(MULTIPLEXER)
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/**
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* mux_control_states() - Query the number of multiplexer states.
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* @mux: The mux-control to query.
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*
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* Return: The number of multiplexer states.
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*/
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unsigned int mux_control_states(struct mux_control *mux);
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/**
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* mux_control_select() - Select the given multiplexer state.
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* @mux: The mux-control to request a change of state from.
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* @state: The new requested state.
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*
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* On successfully selecting the mux-control state, it will be locked until
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* there is a call to mux_control_deselect(). If the mux-control is already
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* selected when mux_control_select() is called, the function will indicate
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* -EBUSY
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*
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* Therefore, make sure to call mux_control_deselect() when the operation is
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* complete and the mux-control is free for others to use, but do not call
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* mux_control_deselect() if mux_control_select() fails.
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*
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* Return: 0 when the mux-control state has the requested state or a negative
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* errno on error.
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*/
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int __must_check mux_control_select(struct mux_control *mux,
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unsigned int state);
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#define mux_control_try_select(mux, state) mux_control_select(mux, state)
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/**
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* mux_control_deselect() - Deselect the previously selected multiplexer state.
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* @mux: The mux-control to deselect.
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*
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* It is required that a single call is made to mux_control_deselect() for
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* each and every successful call made to either of mux_control_select() or
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* mux_control_try_select().
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*
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* Return: 0 on success and a negative errno on error. An error can only
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* occur if the mux has an idle state. Note that even if an error occurs, the
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* mux-control is unlocked and is thus free for the next access.
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*/
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int mux_control_deselect(struct mux_control *mux);
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/**
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* mux_get_by_index() = Get a mux by integer index.
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* @dev: The client device.
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* @index: The index of the mux to get.
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* @mux: A pointer to the 'mux_control' struct to initialize.
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*
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* This looks up and initializes a mux. The index is relative to the client
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* device.
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*
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* Return: 0 if OK, or a negative error code.
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*/
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int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux);
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/**
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* mux_control_get() - Get the mux-control for a device.
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* @dev: The device that needs a mux-control.
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* @mux_name: The name identifying the mux-control.
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* @mux: A pointer to the mux-control pointer.
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*
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* Return: 0 of OK, or a negative error code.
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*/
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int mux_control_get(struct udevice *dev, const char *name,
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struct mux_control **mux);
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/**
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* mux_control_put() - Put away the mux-control for good.
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* @mux: The mux-control to put away.
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*
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* mux_control_put() reverses the effects of mux_control_get().
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*/
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void mux_control_put(struct mux_control *mux);
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/**
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* devm_mux_control_get() - Get the mux-control for a device, with resource
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* management.
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* @dev: The device that needs a mux-control.
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* @mux_name: The name identifying the mux-control.
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*
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* Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
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*/
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struct mux_control *devm_mux_control_get(struct udevice *dev,
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const char *mux_name);
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/**
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* dm_mux_init() - Initialize the multiplexer controls to their default state.
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*
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* Return: 0 if OK, -errno otherwise.
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*/
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int dm_mux_init(void);
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#else
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unsigned int mux_control_states(struct mux_control *mux)
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{
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return -ENOSYS;
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}
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int __must_check mux_control_select(struct mux_control *mux,
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unsigned int state)
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{
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return -ENOSYS;
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}
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#define mux_control_try_select(mux, state) mux_control_select(mux, state)
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int mux_control_deselect(struct mux_control *mux)
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{
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return -ENOSYS;
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}
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struct mux_control *mux_control_get(struct udevice *dev, const char *mux_name)
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{
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return NULL;
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}
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void mux_control_put(struct mux_control *mux)
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{
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}
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struct mux_control *devm_mux_control_get(struct udevice *dev,
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const char *mux_name)
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{
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return NULL;
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}
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int dm_mux_init(void)
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{
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return -ENOSYS;
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}
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#endif
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#endif
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