// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2018-2020 Broadcom */

#include <linux/device.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>

#define BRCM_RESCAL_START       0x0
#define  BRCM_RESCAL_START_BIT  BIT(0)
#define BRCM_RESCAL_CTRL        0x4
#define BRCM_RESCAL_STATUS      0x8
#define  BRCM_RESCAL_STATUS_BIT BIT(0)

struct brcm_rescal_reset {
        void __iomem *base;
        struct device *dev;
        struct reset_controller_dev rcdev;
};

static int brcm_rescal_reset_set(struct reset_controller_dev *rcdev,
                                 unsigned long id)
{
        struct brcm_rescal_reset *data =
                container_of(rcdev, struct brcm_rescal_reset, rcdev);
        void __iomem *base = data->base;
        u32 reg;
        int ret;

        reg = readl(base + BRCM_RESCAL_START);
        writel(reg | BRCM_RESCAL_START_BIT, base + BRCM_RESCAL_START);
        reg = readl(base + BRCM_RESCAL_START);
        if (!(reg & BRCM_RESCAL_START_BIT)) {
                dev_err(data->dev, "failed to start SATA/PCIe rescal\n");
                return -EIO;
        }

        ret = readl_poll_timeout(base + BRCM_RESCAL_STATUS, reg,
                                 (reg & BRCM_RESCAL_STATUS_BIT), 100, 1000);
        if (ret) {
                dev_err(data->dev, "time out on SATA/PCIe rescal\n");
                return ret;
        }

        reg = readl(base + BRCM_RESCAL_START);
        writel(reg & ~BRCM_RESCAL_START_BIT, base + BRCM_RESCAL_START);

        dev_dbg(data->dev, "SATA/PCIe rescal success\n");

        return 0;
}

static int brcm_rescal_reset_xlate(struct reset_controller_dev *rcdev,
                                   const struct of_phandle_args *reset_spec)
{
        /* This is needed if #reset-cells == 0. */
        return 0;
}

static const struct reset_control_ops brcm_rescal_reset_ops = {
        .reset = brcm_rescal_reset_set,
};

static int brcm_rescal_reset_probe(struct platform_device *pdev)
{
        struct brcm_rescal_reset *data;

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

        data->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(data->base))
                return PTR_ERR(data->base);

        data->rcdev.owner = THIS_MODULE;
        data->rcdev.nr_resets = 1;
        data->rcdev.ops = &brcm_rescal_reset_ops;
        data->rcdev.of_node = pdev->dev.of_node;
        data->rcdev.of_xlate = brcm_rescal_reset_xlate;
        data->dev = &pdev->dev;

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

static const struct of_device_id brcm_rescal_reset_of_match[] = {
        { .compatible = "brcm,bcm7216-pcie-sata-rescal" },
        { },
};
MODULE_DEVICE_TABLE(of, brcm_rescal_reset_of_match);

static struct platform_driver brcm_rescal_reset_driver = {
        .probe = brcm_rescal_reset_probe,
        .driver = {
                .name   = "brcm-rescal-reset",
                .of_match_table = brcm_rescal_reset_of_match,
        }
};
module_platform_driver(brcm_rescal_reset_driver);

MODULE_AUTHOR("Broadcom");
MODULE_DESCRIPTION("Broadcom SATA/PCIe rescal reset controller");
MODULE_LICENSE("GPL v2");