548 lines
14 KiB
C
548 lines
14 KiB
C
/*
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* Multiplexer subsystem
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*
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* Copyright (C) 2017 Axentia Technologies AB
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*
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* Author: Peter Rosin <peda@axentia.se>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) "mux-core: " fmt
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#include <linux/idr.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/mux/consumer.h>
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#include <linux/mux/driver.h>
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#include <linux/of.h>
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#include <linux/of_platform.h>
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#include <linux/slab.h>
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/*
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* The idle-as-is "state" is not an actual state that may be selected, it
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* only implies that the state should not be changed. So, use that state
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* as indication that the cached state of the multiplexer is unknown.
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*/
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#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
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static struct class mux_class = {
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.name = "mux",
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.owner = THIS_MODULE,
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};
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static DEFINE_IDA(mux_ida);
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static int __init mux_init(void)
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{
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ida_init(&mux_ida);
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return class_register(&mux_class);
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}
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static void __exit mux_exit(void)
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{
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class_register(&mux_class);
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ida_destroy(&mux_ida);
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}
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static void mux_chip_release(struct device *dev)
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{
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struct mux_chip *mux_chip = to_mux_chip(dev);
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ida_simple_remove(&mux_ida, mux_chip->id);
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kfree(mux_chip);
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}
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static struct device_type mux_type = {
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.name = "mux-chip",
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.release = mux_chip_release,
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};
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/**
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* mux_chip_alloc() - Allocate a mux-chip.
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* @dev: The parent device implementing the mux interface.
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* @controllers: The number of mux controllers to allocate for this chip.
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* @sizeof_priv: Size of extra memory area for private use by the caller.
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*
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* After allocating the mux-chip with the desired number of mux controllers
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* but before registering the chip, the mux driver is required to configure
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* the number of valid mux states in the mux_chip->mux[N].states members and
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* the desired idle state in the returned mux_chip->mux[N].idle_state members.
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* The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to
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* provide a pointer to the operations struct in the mux_chip->ops member
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* before registering the mux-chip with mux_chip_register.
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*
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* Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
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*/
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struct mux_chip *mux_chip_alloc(struct device *dev,
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unsigned int controllers, size_t sizeof_priv)
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{
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struct mux_chip *mux_chip;
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int i;
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if (WARN_ON(!dev || !controllers))
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return ERR_PTR(-EINVAL);
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mux_chip = kzalloc(sizeof(*mux_chip) +
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controllers * sizeof(*mux_chip->mux) +
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sizeof_priv, GFP_KERNEL);
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if (!mux_chip)
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return ERR_PTR(-ENOMEM);
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mux_chip->mux = (struct mux_control *)(mux_chip + 1);
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mux_chip->dev.class = &mux_class;
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mux_chip->dev.type = &mux_type;
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mux_chip->dev.parent = dev;
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mux_chip->dev.of_node = dev->of_node;
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dev_set_drvdata(&mux_chip->dev, mux_chip);
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mux_chip->id = ida_simple_get(&mux_ida, 0, 0, GFP_KERNEL);
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if (mux_chip->id < 0) {
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int err = mux_chip->id;
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pr_err("muxchipX failed to get a device id\n");
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kfree(mux_chip);
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return ERR_PTR(err);
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}
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dev_set_name(&mux_chip->dev, "muxchip%d", mux_chip->id);
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mux_chip->controllers = controllers;
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for (i = 0; i < controllers; ++i) {
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struct mux_control *mux = &mux_chip->mux[i];
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mux->chip = mux_chip;
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sema_init(&mux->lock, 1);
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mux->cached_state = MUX_CACHE_UNKNOWN;
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mux->idle_state = MUX_IDLE_AS_IS;
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}
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device_initialize(&mux_chip->dev);
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return mux_chip;
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}
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EXPORT_SYMBOL_GPL(mux_chip_alloc);
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static int mux_control_set(struct mux_control *mux, int state)
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{
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int ret = mux->chip->ops->set(mux, state);
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mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
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return ret;
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}
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/**
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* mux_chip_register() - Register a mux-chip, thus readying the controllers
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* for use.
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* @mux_chip: The mux-chip to register.
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*
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* Do not retry registration of the same mux-chip on failure. You should
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* instead put it away with mux_chip_free() and allocate a new one, if you
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* for some reason would like to retry registration.
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*
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* Return: Zero on success or a negative errno on error.
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*/
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int mux_chip_register(struct mux_chip *mux_chip)
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{
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int i;
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int ret;
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for (i = 0; i < mux_chip->controllers; ++i) {
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struct mux_control *mux = &mux_chip->mux[i];
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if (mux->idle_state == mux->cached_state)
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continue;
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ret = mux_control_set(mux, mux->idle_state);
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if (ret < 0) {
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dev_err(&mux_chip->dev, "unable to set idle state\n");
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return ret;
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}
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}
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ret = device_add(&mux_chip->dev);
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if (ret < 0)
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dev_err(&mux_chip->dev,
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"device_add failed in %s: %d\n", __func__, ret);
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return ret;
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}
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EXPORT_SYMBOL_GPL(mux_chip_register);
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/**
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* mux_chip_unregister() - Take the mux-chip off-line.
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* @mux_chip: The mux-chip to unregister.
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*
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* mux_chip_unregister() reverses the effects of mux_chip_register().
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* But not completely, you should not try to call mux_chip_register()
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* on a mux-chip that has been registered before.
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*/
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void mux_chip_unregister(struct mux_chip *mux_chip)
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{
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device_del(&mux_chip->dev);
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}
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EXPORT_SYMBOL_GPL(mux_chip_unregister);
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/**
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* mux_chip_free() - Free the mux-chip for good.
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* @mux_chip: The mux-chip to free.
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*
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* mux_chip_free() reverses the effects of mux_chip_alloc().
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*/
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void mux_chip_free(struct mux_chip *mux_chip)
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{
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if (!mux_chip)
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return;
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put_device(&mux_chip->dev);
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}
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EXPORT_SYMBOL_GPL(mux_chip_free);
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static void devm_mux_chip_release(struct device *dev, void *res)
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{
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struct mux_chip *mux_chip = *(struct mux_chip **)res;
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mux_chip_free(mux_chip);
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}
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/**
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* devm_mux_chip_alloc() - Resource-managed version of mux_chip_alloc().
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* @dev: The parent device implementing the mux interface.
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* @controllers: The number of mux controllers to allocate for this chip.
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* @sizeof_priv: Size of extra memory area for private use by the caller.
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*
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* See mux_chip_alloc() for more details.
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*
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* Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
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*/
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struct mux_chip *devm_mux_chip_alloc(struct device *dev,
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unsigned int controllers,
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size_t sizeof_priv)
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{
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struct mux_chip **ptr, *mux_chip;
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ptr = devres_alloc(devm_mux_chip_release, sizeof(*ptr), GFP_KERNEL);
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if (!ptr)
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return ERR_PTR(-ENOMEM);
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mux_chip = mux_chip_alloc(dev, controllers, sizeof_priv);
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if (IS_ERR(mux_chip)) {
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devres_free(ptr);
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return mux_chip;
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}
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*ptr = mux_chip;
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devres_add(dev, ptr);
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return mux_chip;
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}
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EXPORT_SYMBOL_GPL(devm_mux_chip_alloc);
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static void devm_mux_chip_reg_release(struct device *dev, void *res)
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{
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struct mux_chip *mux_chip = *(struct mux_chip **)res;
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mux_chip_unregister(mux_chip);
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}
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/**
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* devm_mux_chip_register() - Resource-managed version mux_chip_register().
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* @dev: The parent device implementing the mux interface.
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* @mux_chip: The mux-chip to register.
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*
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* See mux_chip_register() for more details.
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*
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* Return: Zero on success or a negative errno on error.
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*/
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int devm_mux_chip_register(struct device *dev,
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struct mux_chip *mux_chip)
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{
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struct mux_chip **ptr;
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int res;
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ptr = devres_alloc(devm_mux_chip_reg_release, sizeof(*ptr), GFP_KERNEL);
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if (!ptr)
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return -ENOMEM;
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res = mux_chip_register(mux_chip);
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if (res) {
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devres_free(ptr);
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return res;
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}
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*ptr = mux_chip;
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devres_add(dev, ptr);
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return res;
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}
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EXPORT_SYMBOL_GPL(devm_mux_chip_register);
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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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return mux->states;
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}
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EXPORT_SYMBOL_GPL(mux_control_states);
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/*
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* The mux->lock must be down when calling this function.
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*/
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static int __mux_control_select(struct mux_control *mux, int state)
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{
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int ret;
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if (WARN_ON(state < 0 || state >= mux->states))
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return -EINVAL;
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if (mux->cached_state == state)
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return 0;
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ret = mux_control_set(mux, state);
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if (ret >= 0)
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return 0;
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/* The mux update failed, try to revert if appropriate... */
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if (mux->idle_state != MUX_IDLE_AS_IS)
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mux_control_set(mux, mux->idle_state);
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return ret;
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}
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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 caller will be blocked
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* until mux_control_deselect() is called (by someone else).
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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 mux_control_select(struct mux_control *mux, unsigned int state)
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{
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int ret;
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ret = down_killable(&mux->lock);
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if (ret < 0)
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return ret;
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ret = __mux_control_select(mux, state);
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if (ret < 0)
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up(&mux->lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(mux_control_select);
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/**
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* mux_control_try_select() - Try to 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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* mux_control_deselect() called.
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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_try_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. Specifically -EBUSY if the mux-control is contended.
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*/
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int mux_control_try_select(struct mux_control *mux, unsigned int state)
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{
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int ret;
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if (down_trylock(&mux->lock))
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return -EBUSY;
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ret = __mux_control_select(mux, state);
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if (ret < 0)
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up(&mux->lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(mux_control_try_select);
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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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int ret = 0;
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if (mux->idle_state != MUX_IDLE_AS_IS &&
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mux->idle_state != mux->cached_state)
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ret = mux_control_set(mux, mux->idle_state);
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up(&mux->lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(mux_control_deselect);
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static int of_dev_node_match(struct device *dev, const void *data)
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{
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return dev->of_node == data;
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}
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static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
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{
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struct device *dev;
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dev = class_find_device(&mux_class, NULL, np, of_dev_node_match);
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return dev ? to_mux_chip(dev) : NULL;
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}
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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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*
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* Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
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*/
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struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
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{
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struct device_node *np = dev->of_node;
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struct of_phandle_args args;
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struct mux_chip *mux_chip;
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unsigned int controller;
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int index = 0;
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int ret;
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if (mux_name) {
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index = of_property_match_string(np, "mux-control-names",
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mux_name);
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if (index < 0) {
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dev_err(dev, "mux controller '%s' not found\n",
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mux_name);
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return ERR_PTR(index);
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}
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}
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ret = of_parse_phandle_with_args(np,
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"mux-controls", "#mux-control-cells",
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index, &args);
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if (ret) {
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dev_err(dev, "%s: failed to get mux-control %s(%i)\n",
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np->full_name, mux_name ?: "", index);
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return ERR_PTR(ret);
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}
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mux_chip = of_find_mux_chip_by_node(args.np);
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of_node_put(args.np);
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if (!mux_chip)
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return ERR_PTR(-EPROBE_DEFER);
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if (args.args_count > 1 ||
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(!args.args_count && (mux_chip->controllers > 1))) {
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dev_err(dev, "%s: wrong #mux-control-cells for %s\n",
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np->full_name, args.np->full_name);
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return ERR_PTR(-EINVAL);
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}
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controller = 0;
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if (args.args_count)
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controller = args.args[0];
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if (controller >= mux_chip->controllers) {
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dev_err(dev, "%s: bad mux controller %u specified in %s\n",
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np->full_name, controller, args.np->full_name);
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return ERR_PTR(-EINVAL);
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}
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get_device(&mux_chip->dev);
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return &mux_chip->mux[controller];
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}
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EXPORT_SYMBOL_GPL(mux_control_get);
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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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put_device(&mux->chip->dev);
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}
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EXPORT_SYMBOL_GPL(mux_control_put);
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static void devm_mux_control_release(struct device *dev, void *res)
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{
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struct mux_control *mux = *(struct mux_control **)res;
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mux_control_put(mux);
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}
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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 device *dev,
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const char *mux_name)
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{
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struct mux_control **ptr, *mux;
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ptr = devres_alloc(devm_mux_control_release, sizeof(*ptr), GFP_KERNEL);
|
|
if (!ptr)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
mux = mux_control_get(dev, mux_name);
|
|
if (IS_ERR(mux)) {
|
|
devres_free(ptr);
|
|
return mux;
|
|
}
|
|
|
|
*ptr = mux;
|
|
devres_add(dev, ptr);
|
|
|
|
return mux;
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_mux_control_get);
|
|
|
|
/*
|
|
* Using subsys_initcall instead of module_init here to try to ensure - for
|
|
* the non-modular case - that the subsystem is initialized when mux consumers
|
|
* and mux controllers start to use it.
|
|
* For the modular case, the ordering is ensured with module dependencies.
|
|
*/
|
|
subsys_initcall(mux_init);
|
|
module_exit(mux_exit);
|
|
|
|
MODULE_DESCRIPTION("Multiplexer subsystem");
|
|
MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
|
|
MODULE_LICENSE("GPL v2");
|