linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * Multiplexer subsystem

 *

 * Copyright (C) 2017 Axentia Technologies AB

 *

 * Author: Peter Rosin <peda@axentia.se>

 */

​

#define pr_fmt(fmt) "mux-core: " fmt

​

#include <linux/device.h>

#include <linux/err.h>

#include <linux/export.h>

#include <linux/idr.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/mux/consumer.h>

#include <linux/mux/driver.h>

#include <linux/of.h>

#include <linux/of_platform.h>

#include <linux/slab.h>

​

/*

 * The idle-as-is "state" is not an actual state that may be selected, it

 * only implies that the state should not be changed. So, use that state

 * as indication that the cached state of the multiplexer is unknown.

 */

#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS

​

static struct class mux_class = {

    .name = "mux",

    .owner = THIS_MODULE,

};

​

static DEFINE_IDA(mux_ida);

​

static int __init mux_init(void)

{

    ida_init(&mux_ida);

    return class_register(&mux_class);

}

​

static void __exit mux_exit(void)

{

    class_unregister(&mux_class);

    ida_destroy(&mux_ida);

}

​

static void mux_chip_release(struct device *dev)

{

    struct mux_chip *mux_chip = to_mux_chip(dev);

​

    ida_simple_remove(&mux_ida, mux_chip->id);

    kfree(mux_chip);

}

​

static const struct device_type mux_type = {

    .name = "mux-chip",

    .release = mux_chip_release,

};

​

/**

 * mux_chip_alloc() - Allocate a mux-chip.

 * @dev: The parent device implementing the mux interface.

 * @controllers: The number of mux controllers to allocate for this chip.

 * @sizeof_priv: Size of extra memory area for private use by the caller.

 *

 * After allocating the mux-chip with the desired number of mux controllers

 * but before registering the chip, the mux driver is required to configure

 * the number of valid mux states in the mux_chip->mux[N].states members and

 * the desired idle state in the returned mux_chip->mux[N].idle_state members.

 * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to

 * provide a pointer to the operations struct in the mux_chip->ops member

 * before registering the mux-chip with mux_chip_register.

 *

 * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.

 */

struct mux_chip *mux_chip_alloc(struct device *dev,

                unsigned int controllers, size_t sizeof_priv)

{

    struct mux_chip *mux_chip;

    int i;

​

    if (WARN_ON(!dev || !controllers))

        return ERR_PTR(-EINVAL);

​

    mux_chip = kzalloc(sizeof(*mux_chip) +

               controllers * sizeof(*mux_chip->mux) +

               sizeof_priv, GFP_KERNEL);

    if (!mux_chip)

        return ERR_PTR(-ENOMEM);