// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2019 NXP
 */

#include <linux/clk.h>
#include <linux/devfreq.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pm_opp.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

struct imx_bus {
        struct devfreq_dev_profile profile;
        struct devfreq *devfreq;
        struct clk *clk;
        struct platform_device *icc_pdev;
};

static int imx_bus_target(struct device *dev,
                unsigned long *freq, u32 flags)
{
        struct dev_pm_opp *new_opp;
        int ret;

        new_opp = devfreq_recommended_opp(dev, freq, flags);
        if (IS_ERR(new_opp)) {
                ret = PTR_ERR(new_opp);
                dev_err(dev, "failed to get recommended opp: %d\n", ret);
                return ret;
        }
        dev_pm_opp_put(new_opp);

        return dev_pm_opp_set_rate(dev, *freq);
}

static int imx_bus_get_cur_freq(struct device *dev, unsigned long *freq)
{
        struct imx_bus *priv = dev_get_drvdata(dev);

        *freq = clk_get_rate(priv->clk);

        return 0;
}

static int imx_bus_get_dev_status(struct device *dev,
                struct devfreq_dev_status *stat)
{
        struct imx_bus *priv = dev_get_drvdata(dev);

        stat->busy_time = 0;
        stat->total_time = 0;
        stat->current_frequency = clk_get_rate(priv->clk);

        return 0;
}

static void imx_bus_exit(struct device *dev)
{
        struct imx_bus *priv = dev_get_drvdata(dev);

        dev_pm_opp_of_remove_table(dev);
        platform_device_unregister(priv->icc_pdev);
}

/* imx_bus_init_icc() - register matching icc provider if required */
static int imx_bus_init_icc(struct device *dev)
{
        struct imx_bus *priv = dev_get_drvdata(dev);
        const char *icc_driver_name;

        if (!of_get_property(dev->of_node, "#interconnect-cells", 0))
                return 0;
        if (!IS_ENABLED(CONFIG_INTERCONNECT_IMX)) {
                dev_warn(dev, "imx interconnect drivers disabled\n");
                return 0;
        }

        icc_driver_name = of_device_get_match_data(dev);
        if (!icc_driver_name) {
                dev_err(dev, "unknown interconnect driver\n");
                return 0;
        }

        priv->icc_pdev = platform_device_register_data(
                        dev, icc_driver_name, -1, NULL, 0);
        if (IS_ERR(priv->icc_pdev)) {
                dev_err(dev, "failed to register icc provider %s: %ld\n",
                                icc_driver_name, PTR_ERR(priv->icc_pdev));
                return PTR_ERR(priv->icc_pdev);
        }

        return 0;
}

static int imx_bus_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct imx_bus *priv;
        const char *gov = DEVFREQ_GOV_USERSPACE;
        int ret;

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

        /*
         * Fetch the clock to adjust but don't explicitly enable.
         *
         * For imx bus clock clk_set_rate is safe no matter if the clock is on
         * or off and some peripheral side-buses might be off unless enabled by
         * drivers for devices on those specific buses.
         *
         * Rate adjustment on a disabled bus clock just takes effect later.
         */
        priv->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(priv->clk)) {
                ret = PTR_ERR(priv->clk);
                dev_err(dev, "failed to fetch clk: %d\n", ret);
                return ret;
        }
        platform_set_drvdata(pdev, priv);

        ret = dev_pm_opp_of_add_table(dev);
        if (ret < 0) {
                dev_err(dev, "failed to get OPP table\n");
                return ret;
        }

        priv->profile.polling_ms = 1000;
        priv->profile.target = imx_bus_target;
        priv->profile.get_dev_status = imx_bus_get_dev_status;
        priv->profile.exit = imx_bus_exit;
        priv->profile.get_cur_freq = imx_bus_get_cur_freq;
        priv->profile.initial_freq = clk_get_rate(priv->clk);

        priv->devfreq = devm_devfreq_add_device(dev, &priv->profile,
                                                gov, NULL);
        if (IS_ERR(priv->devfreq)) {
                ret = PTR_ERR(priv->devfreq);
                dev_err(dev, "failed to add devfreq device: %d\n", ret);
                goto err;
        }

        ret = imx_bus_init_icc(dev);
        if (ret)
                goto err;

        return 0;

err:
        dev_pm_opp_of_remove_table(dev);
        return ret;
}

static const struct of_device_id imx_bus_of_match[] = {
        { .compatible = "fsl,imx8mq-noc", .data = "imx8mq-interconnect", },
        { .compatible = "fsl,imx8mm-noc", .data = "imx8mm-interconnect", },
        { .compatible = "fsl,imx8mn-noc", .data = "imx8mn-interconnect", },
        { .compatible = "fsl,imx8m-noc", },
        { .compatible = "fsl,imx8m-nic", },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, imx_bus_of_match);

static struct platform_driver imx_bus_platdrv = {
        .probe          = imx_bus_probe,
        .driver = {
                .name   = "imx-bus-devfreq",
                .of_match_table = of_match_ptr(imx_bus_of_match),
        },
};
module_platform_driver(imx_bus_platdrv);

MODULE_DESCRIPTION("Generic i.MX bus frequency scaling driver");
MODULE_AUTHOR("Leonard Crestez <leonard.crestez@nxp.com>");
MODULE_LICENSE("GPL v2");