// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 *  Copyright (C) 2010 John Crispin <blogic@phrozen.org>
 *  Copyright (C) 2013-2015 Lantiq Beteiligungs-GmbH & Co.KG
 *  Copyright (C) 2016 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
 *  Copyright (C) 2017 Hauke Mehrtens <hauke@hauke-m.de>
 */

#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/reset-controller.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/property.h>

#define LANTIQ_RCU_RESET_TIMEOUT        10000

struct lantiq_rcu_reset_priv {
        struct reset_controller_dev rcdev;
        struct device *dev;
        struct regmap *regmap;
        u32 reset_offset;
        u32 status_offset;
};

static struct lantiq_rcu_reset_priv *to_lantiq_rcu_reset_priv(
        struct reset_controller_dev *rcdev)
{
        return container_of(rcdev, struct lantiq_rcu_reset_priv, rcdev);
}

static int lantiq_rcu_reset_status(struct reset_controller_dev *rcdev,
                                   unsigned long id)
{
        struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
        unsigned int status = (id >> 8) & 0x1f;
        u32 val;
        int ret;

        ret = regmap_read(priv->regmap, priv->status_offset, &val);
        if (ret)
                return ret;

        return !!(val & BIT(status));
}

static int lantiq_rcu_reset_status_timeout(struct reset_controller_dev *rcdev,
                                           unsigned long id, bool assert)
{
        int ret;
        int retry = LANTIQ_RCU_RESET_TIMEOUT;

        do {
                ret = lantiq_rcu_reset_status(rcdev, id);
                if (ret < 0)
                        return ret;
                if (ret == assert)
                        return 0;
                usleep_range(20, 40);
        } while (--retry);

        return -ETIMEDOUT;
}

static int lantiq_rcu_reset_update(struct reset_controller_dev *rcdev,
                                   unsigned long id, bool assert)
{
        struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
        unsigned int set = id & 0x1f;
        u32 val = assert ? BIT(set) : 0;
        int ret;

        ret = regmap_update_bits(priv->regmap, priv->reset_offset, BIT(set),
                                 val);
        if (ret) {
                dev_err(priv->dev, "Failed to set reset bit %u\n", set);
                return ret;
        }


        ret = lantiq_rcu_reset_status_timeout(rcdev, id, assert);
        if (ret)
                dev_err(priv->dev, "Failed to %s bit %u\n",
                        assert ? "assert" : "deassert", set);

        return ret;
}

static int lantiq_rcu_reset_assert(struct reset_controller_dev *rcdev,
                             unsigned long id)
{
        return lantiq_rcu_reset_update(rcdev, id, true);
}

static int lantiq_rcu_reset_deassert(struct reset_controller_dev *rcdev,
                               unsigned long id)
{
        return lantiq_rcu_reset_update(rcdev, id, false);
}

static int lantiq_rcu_reset_reset(struct reset_controller_dev *rcdev,
                            unsigned long id)
{
        int ret;

        ret = lantiq_rcu_reset_assert(rcdev, id);
        if (ret)
                return ret;

        return lantiq_rcu_reset_deassert(rcdev, id);
}

static const struct reset_control_ops lantiq_rcu_reset_ops = {
        .assert = lantiq_rcu_reset_assert,
        .deassert = lantiq_rcu_reset_deassert,
        .status = lantiq_rcu_reset_status,
        .reset  = lantiq_rcu_reset_reset,
};

static int lantiq_rcu_reset_of_parse(struct platform_device *pdev,
                               struct lantiq_rcu_reset_priv *priv)
{
        struct device *dev = &pdev->dev;
        const __be32 *offset;

        priv->regmap = syscon_node_to_regmap(dev->of_node->parent);
        if (IS_ERR(priv->regmap)) {
                dev_err(&pdev->dev, "Failed to lookup RCU regmap\n");
                return PTR_ERR(priv->regmap);
        }

        offset = of_get_address(dev->of_node, 0, NULL, NULL);
        if (!offset) {
                dev_err(&pdev->dev, "Failed to get RCU reset offset\n");
                return -ENOENT;
        }
        priv->reset_offset = __be32_to_cpu(*offset);

        offset = of_get_address(dev->of_node, 1, NULL, NULL);
        if (!offset) {
                dev_err(&pdev->dev, "Failed to get RCU status offset\n");
                return -ENOENT;
        }
        priv->status_offset = __be32_to_cpu(*offset);

        return 0;
}

static int lantiq_rcu_reset_xlate(struct reset_controller_dev *rcdev,
                                  const struct of_phandle_args *reset_spec)
{
        unsigned int status, set;

        set = reset_spec->args[0];
        status = reset_spec->args[1];

        if (set >= rcdev->nr_resets || status >= rcdev->nr_resets)
                return -EINVAL;

        return (status << 8) | set;
}

static int lantiq_rcu_reset_probe(struct platform_device *pdev)
{
        struct lantiq_rcu_reset_priv *priv;
        int err;

        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->dev = &pdev->dev;

        err = lantiq_rcu_reset_of_parse(pdev, priv);
        if (err)
                return err;

        priv->rcdev.ops = &lantiq_rcu_reset_ops;
        priv->rcdev.owner = THIS_MODULE;
        priv->rcdev.of_node = pdev->dev.of_node;
        priv->rcdev.nr_resets = 32;
        priv->rcdev.of_xlate = lantiq_rcu_reset_xlate;
        priv->rcdev.of_reset_n_cells = 2;

        return devm_reset_controller_register(&pdev->dev, &priv->rcdev);
}

static const struct of_device_id lantiq_rcu_reset_dt_ids[] = {
        { .compatible = "lantiq,danube-reset", },
        { .compatible = "lantiq,xrx200-reset", },
        { },
};
MODULE_DEVICE_TABLE(of, lantiq_rcu_reset_dt_ids);

static struct platform_driver lantiq_rcu_reset_driver = {
        .probe  = lantiq_rcu_reset_probe,
        .driver = {
                .name           = "lantiq-reset",
                .of_match_table = lantiq_rcu_reset_dt_ids,
        },
};
module_platform_driver(lantiq_rcu_reset_driver);

MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
MODULE_DESCRIPTION("Lantiq XWAY RCU Reset Controller Driver");