// SPDX-License-Identifier: GPL-2.0
/*
 * Broadcom STB generic reset controller for SW_INIT style reset controller
 *
 * Author: Florian Fainelli <f.fainelli@gmail.com>
 * Copyright (C) 2018 Broadcom
 */
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/types.h>

struct brcmstb_reset {
        void __iomem *base;
        struct reset_controller_dev rcdev;
};

#define SW_INIT_SET             0x00
#define SW_INIT_CLEAR           0x04
#define SW_INIT_STATUS          0x08

#define SW_INIT_BIT(id)         BIT((id) & 0x1f)
#define SW_INIT_BANK(id)        ((id) >> 5)

/* A full bank contains extra registers that we are not utilizing but still
 * qualify as a single bank.
 */
#define SW_INIT_BANK_SIZE       0x18

static inline
struct brcmstb_reset *to_brcmstb(struct reset_controller_dev *rcdev)
{
        return container_of(rcdev, struct brcmstb_reset, rcdev);
}

static int brcmstb_reset_assert(struct reset_controller_dev *rcdev,
                                unsigned long id)
{
        unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
        struct brcmstb_reset *priv = to_brcmstb(rcdev);

        writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_SET);

        return 0;
}

static int brcmstb_reset_deassert(struct reset_controller_dev *rcdev,
                                  unsigned long id)
{
        unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
        struct brcmstb_reset *priv = to_brcmstb(rcdev);

        writel_relaxed(SW_INIT_BIT(id), priv->base + off + SW_INIT_CLEAR);
        /* Maximum reset delay after de-asserting a line and seeing block
         * operation is typically 14us for the worst case, build some slack
         * here.
         */
        usleep_range(100, 200);

        return 0;
}

static int brcmstb_reset_status(struct reset_controller_dev *rcdev,
                                unsigned long id)
{
        unsigned int off = SW_INIT_BANK(id) * SW_INIT_BANK_SIZE;
        struct brcmstb_reset *priv = to_brcmstb(rcdev);

        return readl_relaxed(priv->base + off + SW_INIT_STATUS) &
                             SW_INIT_BIT(id);
}

static const struct reset_control_ops brcmstb_reset_ops = {
        .assert = brcmstb_reset_assert,
        .deassert = brcmstb_reset_deassert,
        .status = brcmstb_reset_status,
};

static int brcmstb_reset_probe(struct platform_device *pdev)
{
        struct device *kdev = &pdev->dev;
        struct brcmstb_reset *priv;
        struct resource *res;

        priv = devm_kzalloc(kdev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(priv->base))
                return PTR_ERR(priv->base);

        dev_set_drvdata(kdev, priv);

        priv->rcdev.owner = THIS_MODULE;
        priv->rcdev.nr_resets = DIV_ROUND_DOWN_ULL(resource_size(res),
                                                   SW_INIT_BANK_SIZE) * 32;
        priv->rcdev.ops = &brcmstb_reset_ops;
        priv->rcdev.of_node = kdev->of_node;
        /* Use defaults: 1 cell and simple xlate function */

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

static const struct of_device_id brcmstb_reset_of_match[] = {
        { .compatible = "brcm,brcmstb-reset" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, brcmstb_reset_of_match);

static struct platform_driver brcmstb_reset_driver = {
        .probe  = brcmstb_reset_probe,
        .driver = {
                .name = "brcmstb-reset",
                .of_match_table = brcmstb_reset_of_match,
        },
};
module_platform_driver(brcmstb_reset_driver);

MODULE_AUTHOR("Broadcom");
MODULE_DESCRIPTION("Broadcom STB reset controller");
MODULE_LICENSE("GPL");