// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C multiplexer using pinctrl API
 *
 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
 */

#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/of.h>
#include "../../pinctrl/core.h"

struct i2c_mux_pinctrl {
        struct pinctrl *pinctrl;
        struct pinctrl_state *states[];
};

static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
{
        struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);

        return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
}

static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
{
        return i2c_mux_pinctrl_select(muxc, muxc->num_adapters);
}

static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
        struct pinctrl_state *state)
{
        struct i2c_adapter *root = NULL;
        struct pinctrl_setting *setting;
        struct i2c_adapter *pin_root;

        list_for_each_entry(setting, &state->settings, node) {
                pin_root = i2c_root_adapter(setting->pctldev->dev);
                if (!pin_root)
                        return NULL;
                if (!root)
                        root = pin_root;
                else if (root != pin_root)
                        return NULL;
        }

        return root;
}

static struct i2c_adapter *i2c_mux_pinctrl_parent_adapter(struct device *dev)
{
        struct device_node *np = dev->of_node;
        struct device_node *parent_np;
        struct i2c_adapter *parent;

        parent_np = of_parse_phandle(np, "i2c-parent", 0);
        if (!parent_np) {
                dev_err(dev, "Cannot parse i2c-parent\n");
                return ERR_PTR(-ENODEV);
        }
        parent = of_get_i2c_adapter_by_node(parent_np);
        of_node_put(parent_np);
        if (!parent)
                return ERR_PTR(-EPROBE_DEFER);

        return parent;
}

static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct i2c_mux_core *muxc;
        struct i2c_mux_pinctrl *mux;
        struct i2c_adapter *parent;
        struct i2c_adapter *root;
        int num_names, i, ret;
        const char *name;

        num_names = of_property_count_strings(np, "pinctrl-names");
        if (num_names < 0) {
                dev_err(dev, "Cannot parse pinctrl-names: %d\n",
                        num_names);
                return num_names;
        }

        parent = i2c_mux_pinctrl_parent_adapter(dev);
        if (IS_ERR(parent))
                return PTR_ERR(parent);

        muxc = i2c_mux_alloc(parent, dev, num_names,
                             struct_size(mux, states, num_names),
                             0, i2c_mux_pinctrl_select, NULL);
        if (!muxc) {
                ret = -ENOMEM;
                goto err_put_parent;
        }
        mux = i2c_mux_priv(muxc);

        platform_set_drvdata(pdev, muxc);

        mux->pinctrl = devm_pinctrl_get(dev);
        if (IS_ERR(mux->pinctrl)) {
                ret = PTR_ERR(mux->pinctrl);
                dev_err(dev, "Cannot get pinctrl: %d\n", ret);
                goto err_put_parent;
        }

        for (i = 0; i < num_names; i++) {
                ret = of_property_read_string_index(np, "pinctrl-names", i,
                                                    &name);
                if (ret < 0) {
                        dev_err(dev, "Cannot parse pinctrl-names: %d\n", ret);
                        goto err_put_parent;
                }

                mux->states[i] = pinctrl_lookup_state(mux->pinctrl, name);
                if (IS_ERR(mux->states[i])) {
                        ret = PTR_ERR(mux->states[i]);
                        dev_err(dev, "Cannot look up pinctrl state %s: %d\n",
                                name, ret);
                        goto err_put_parent;
                }

                if (strcmp(name, "idle"))
                        continue;

                if (i != num_names - 1) {
                        dev_err(dev, "idle state must be last\n");
                        ret = -EINVAL;
                        goto err_put_parent;
                }
                muxc->deselect = i2c_mux_pinctrl_deselect;
        }

        root = i2c_root_adapter(&muxc->parent->dev);

        muxc->mux_locked = true;
        for (i = 0; i < num_names; i++) {
                if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
                        muxc->mux_locked = false;
                        break;
                }
        }
        if (muxc->mux_locked)
                dev_info(dev, "mux-locked i2c mux\n");

        /* Do not add any adapter for the idle state (if it's there at all). */
        for (i = 0; i < num_names - !!muxc->deselect; i++) {
                ret = i2c_mux_add_adapter(muxc, 0, i);
                if (ret)
                        goto err_del_adapter;
        }

        return 0;

err_del_adapter:
        i2c_mux_del_adapters(muxc);
err_put_parent:
        i2c_put_adapter(parent);

        return ret;
}

static void i2c_mux_pinctrl_remove(struct platform_device *pdev)
{
        struct i2c_mux_core *muxc = platform_get_drvdata(pdev);

        i2c_mux_del_adapters(muxc);
        i2c_put_adapter(muxc->parent);
}

static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
        { .compatible = "i2c-mux-pinctrl", },
        {},
};
MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);

static struct platform_driver i2c_mux_pinctrl_driver = {
        .driver = {
                .name   = "i2c-mux-pinctrl",
                .of_match_table = i2c_mux_pinctrl_of_match,
        },
        .probe  = i2c_mux_pinctrl_probe,
        .remove = i2c_mux_pinctrl_remove,
};
module_platform_driver(i2c_mux_pinctrl_driver);

MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c-mux-pinctrl");