// SPDX-License-Identifier: GPL-2.0
/*
 * Multiplexer subsystem
 *
 * Based on the linux multiplexer framework
 *
 * Copyright (C) 2017 Axentia Technologies AB
 * Author: Peter Rosin <peda@axentia.se>
 *
 * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
 * Jean-Jacques Hiblot <jjhiblot@ti.com>
 */

#include <common.h>
#include <dm.h>
#include <mux-internal.h>
#include <dm/device-internal.h>
#include <dm/device_compat.h>
#include <dm/devres.h>
#include <dt-bindings/mux/mux.h>
#include <linux/bug.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

/**
 * mux_control_ops() - Get the mux_control ops.
 * @dev: The client device.
 *
 * Return: A pointer to the 'mux_control_ops' of the device.
 */
static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
{
        return (const struct mux_control_ops *)dev->driver->ops;
}

/**
 * mux_control_set() - Set the state of the given mux controller.
 * @mux: A multiplexer control
 * @state: The new requested state.
 *
 * Return: 0 if OK, or a negative error code.
 */
static int mux_control_set(struct mux_control *mux, int state)
{
        int ret = mux_dev_ops(mux->dev)->set(mux, state);

        mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;

        return ret;
}

unsigned int mux_control_states(struct mux_control *mux)
{
        return mux->states;
}

/**
 * __mux_control_select() - Select the given multiplexer state.
 * @mux: The mux-control to request a change of state from.
 * @state: The new requested state.
 *
 * Try to set the mux to the requested state. If not, try to revert if
 * appropriate.
 */
static int __mux_control_select(struct mux_control *mux, int state)
{
        int ret;

        if (WARN_ON(state < 0 || state >= mux->states))
                return -EINVAL;

        if (mux->cached_state == state)
                return 0;

        ret = mux_control_set(mux, state);
        if (ret >= 0)
                return 0;

        /* The mux update failed, try to revert if appropriate... */
        if (mux->idle_state != MUX_IDLE_AS_IS)
                mux_control_set(mux, mux->idle_state);

        return ret;
}

int mux_control_select(struct mux_control *mux, unsigned int state)
{
        int ret;

        if (mux->in_use)
                return -EBUSY;

        ret = __mux_control_select(mux, state);

        if (ret < 0)
                return ret;

        mux->in_use = true;

        return 0;
}

int mux_control_deselect(struct mux_control *mux)
{
        int ret = 0;

        if (mux->idle_state != MUX_IDLE_AS_IS &&
            mux->idle_state != mux->cached_state)
                ret = mux_control_set(mux, mux->idle_state);

        mux->in_use = false;

        return ret;
}

static int mux_of_xlate_default(struct mux_chip *mux_chip,
                                struct ofnode_phandle_args *args,
                                struct mux_control **muxp)
{
        struct mux_control *mux;
        int id;

        log_debug("%s(muxp=%p)\n", __func__, muxp);

        if (args->args_count > 1) {
                debug("Invaild args_count: %d\n", args->args_count);
                return -EINVAL;
        }

        if (args->args_count)
                id = args->args[0];
        else
                id = 0;

        if (id >= mux_chip->controllers) {
                pr_err("bad mux controller %u specified in %s\n",
                        id, ofnode_get_name(args->node));
                return -ERANGE;
        }

        mux = &mux_chip->mux[id];
        mux->id = id;
        *muxp = mux;
        return 0;
}

/**
 * mux_get_by_indexed_prop() - Get a mux control by integer index
 * @dev: The client device.
 * @prop_name: Name of the device tree property.
 * @index: The index of the mux to get
 * @mux: A pointer to the 'mux_control' struct to initialize.
 *
 * Return: 0 of OK, -errno otherwise.
 */
static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
                                   int index, struct mux_control **mux)
{
        int ret;
        struct ofnode_phandle_args args;
        struct udevice *dev_mux;
        const struct mux_control_ops *ops;
        struct mux_chip *mux_chip;

        log_debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);

        ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
                                         0, index, &args);
        if (ret) {
                debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
                      __func__, ret);
                return ret;
        }

        ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
        if (ret) {
                debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
                      __func__, ret);
                return ret;
        }

        mux_chip = dev_get_uclass_priv(dev_mux);

        ops = mux_dev_ops(dev_mux);
        if (ops->of_xlate)
                ret = ops->of_xlate(mux_chip, &args, mux);
        else
                ret = mux_of_xlate_default(mux_chip, &args, mux);
        if (ret) {
                debug("of_xlate() failed: %d\n", ret);
                return ret;
        }
        (*mux)->dev = dev_mux;

        return 0;
}

int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
{
        return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
}

int mux_control_get(struct udevice *dev, const char *name,
                    struct mux_control **mux)
{
        int index;

        debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);

        index = dev_read_stringlist_search(dev, "mux-control-names", name);
        if (index < 0) {
                debug("fdt_stringlist_search() failed: %d\n", index);
                return index;
        }

        return mux_get_by_index(dev, index, mux);
}

void mux_control_put(struct mux_control *mux)
{
        mux_control_deselect(mux);
}

/**
 * devm_mux_control_release() - Release the given managed mux.
 * @dev: The client device.
 * @res: Pointer to the mux to be released.
 *
 * This function is called by devres to release the mux. It reverses the
 * effects of mux_control_get().
 */
static void devm_mux_control_release(struct udevice *dev, void *res)
{
        mux_control_put(*(struct mux_control **)res);
}

struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
{
        int rc;
        struct mux_control **mux;

        mux = devres_alloc(devm_mux_control_release,
                           sizeof(struct mux_control *), __GFP_ZERO);
        if (unlikely(!mux))
                return ERR_PTR(-ENOMEM);

        rc = mux_control_get(dev, id, mux);
        if (rc)
                return ERR_PTR(rc);

        devres_add(dev, mux);
        return *mux;
}

int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
{
        int i;
        struct mux_chip *mux_chip = dev_get_uclass_priv(dev);

        mux_chip->mux = devm_kmalloc(dev,
                                     sizeof(struct mux_control) * controllers,
                                     __GFP_ZERO);
        if (!mux_chip->mux)
                return -ENOMEM;

        mux_chip->controllers = controllers;

        for (i = 0; i < mux_chip->controllers; ++i) {
                struct mux_control *mux = &mux_chip->mux[i];

                mux->dev = dev;
                mux->cached_state = MUX_CACHE_UNKNOWN;
                mux->idle_state = MUX_IDLE_AS_IS;
                mux->in_use = false;
                mux->id = i;
        }

        return 0;
}

static int mux_uclass_post_probe(struct udevice *dev)
{
        int i, ret;
        struct mux_chip *mux_chip = dev_get_uclass_priv(dev);

        /* Set all mux controllers to their idle state. */
        for (i = 0; i < mux_chip->controllers; ++i) {
                struct mux_control *mux = &mux_chip->mux[i];

                if (mux->idle_state == mux->cached_state)
                        continue;

                ret = mux_control_set(mux, mux->idle_state);
                if (ret < 0) {
                        dev_err(dev, "unable to set idle state\n");
                        return ret;
                }
        }
        return 0;
}

int dm_mux_init(void)
{
        struct uclass *uc;
        struct udevice *dev;
        int ret;

        ret = uclass_get(UCLASS_MUX, &uc);
        if (ret < 0) {
                log_debug("unable to get MUX uclass\n");
                return ret;
        }
        uclass_foreach_dev(dev, uc) {
                if (dev_read_bool(dev, "u-boot,mux-autoprobe")) {
                        ret = device_probe(dev);
                        if (ret)
                                log_debug("unable to probe device %s\n",
                                          dev->name);
                }
        }

        return 0;
}

UCLASS_DRIVER(mux) = {
        .id             = UCLASS_MUX,
        .name           = "mux",
        .post_probe     = mux_uclass_post_probe,
        .per_device_auto_alloc_size = sizeof(struct mux_chip),
};