/*
 * Copyright (C) 2014 Marvell Technology Group Ltd.
 *
 * Marvell Berlin reset driver
 *
 * Antoine Tenart <antoine.tenart@free-electrons.com>
 * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
#include <linux/types.h>

#define BERLIN_MAX_RESETS       32

#define to_berlin_reset_priv(p)         \
        container_of((p), struct berlin_reset_priv, rcdev)

struct berlin_reset_priv {
        struct regmap                   *regmap;
        struct reset_controller_dev     rcdev;
};

static int berlin_reset_reset(struct reset_controller_dev *rcdev,
                              unsigned long id)
{
        struct berlin_reset_priv *priv = to_berlin_reset_priv(rcdev);
        int offset = id >> 8;
        int mask = BIT(id & 0x1f);

        regmap_write(priv->regmap, offset, mask);

        /* let the reset be effective */
        udelay(10);

        return 0;
}

static const struct reset_control_ops berlin_reset_ops = {
        .reset  = berlin_reset_reset,
};

static int berlin_reset_xlate(struct reset_controller_dev *rcdev,
                              const struct of_phandle_args *reset_spec)
{
        unsigned int offset, bit;

        offset = reset_spec->args[0];
        bit = reset_spec->args[1];

        if (bit >= BERLIN_MAX_RESETS)
                return -EINVAL;

        return (offset << 8) | bit;
}

static int berlin2_reset_probe(struct platform_device *pdev)
{
        struct device_node *parent_np;
        struct berlin_reset_priv *priv;

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

        parent_np = of_get_parent(pdev->dev.of_node);
        priv->regmap = syscon_node_to_regmap(parent_np);
        of_node_put(parent_np);
        if (IS_ERR(priv->regmap))
                return PTR_ERR(priv->regmap);

        priv->rcdev.owner = THIS_MODULE;
        priv->rcdev.ops = &berlin_reset_ops;
        priv->rcdev.of_node = pdev->dev.of_node;
        priv->rcdev.of_reset_n_cells = 2;
        priv->rcdev.of_xlate = berlin_reset_xlate;

        return reset_controller_register(&priv->rcdev);
}

static const struct of_device_id berlin_reset_dt_match[] = {
        { .compatible = "marvell,berlin2-reset" },
        { },
};
MODULE_DEVICE_TABLE(of, berlin_reset_dt_match);

static struct platform_driver berlin_reset_driver = {
        .probe  = berlin2_reset_probe,
        .driver = {
                .name = "berlin2-reset",
                .of_match_table = berlin_reset_dt_match,
        },
};
module_platform_driver(berlin_reset_driver);

MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
MODULE_AUTHOR("Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>");
MODULE_DESCRIPTION("Synaptics Berlin reset controller");
MODULE_LICENSE("GPL");