// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk>
 * Copyright (C) 2021 Samin Guo <samin.guo@starfivetech.com>
 */

#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reset.h>

/*
 * TempSensor reset. The RSTN can be de-asserted once the analog core has
 * powered up. Trst(min 100ns)
 * 0:reset  1:de-assert
 */
#define SFCTEMP_RSTN    BIT(0)

/*
 * TempSensor analog core power down. The analog core will be powered up
 * Tpu(min 50us) after PD is de-asserted. RSTN should be held low until the
 * analog core is powered up.
 * 0:power up  1:power down
 */
#define SFCTEMP_PD      BIT(1)

/*
 * TempSensor start conversion enable.
 * 0:disable  1:enable
 */
#define SFCTEMP_RUN     BIT(2)

/*
 * TempSensor conversion value output.
 * Temp(C)=DOUT*Y/4094 - K
 */
#define SFCTEMP_DOUT_POS        16
#define SFCTEMP_DOUT_MSK        GENMASK(27, 16)

/* DOUT to Celcius conversion constants */
#define SFCTEMP_Y1000   237500L
#define SFCTEMP_Z       4094L
#define SFCTEMP_K1000   81100L

struct sfctemp {
        void __iomem *regs;
        struct clk *clk_sense;
        struct clk *clk_bus;
        struct reset_control *rst_sense;
        struct reset_control *rst_bus;
        bool enabled;
};

static void sfctemp_power_up(struct sfctemp *sfctemp)
{
        /* make sure we're powered down first */
        writel(SFCTEMP_PD, sfctemp->regs);
        udelay(1);

        writel(0, sfctemp->regs);
        /* wait t_pu(50us) + t_rst(100ns) */
        usleep_range(60, 200);

        /* de-assert reset */
        writel(SFCTEMP_RSTN, sfctemp->regs);
        udelay(1); /* wait t_su(500ps) */
}

static void sfctemp_power_down(struct sfctemp *sfctemp)
{
        writel(SFCTEMP_PD, sfctemp->regs);
}

static void sfctemp_run(struct sfctemp *sfctemp)
{
        writel(SFCTEMP_RSTN | SFCTEMP_RUN, sfctemp->regs);
        udelay(1);
}

static void sfctemp_stop(struct sfctemp *sfctemp)
{
        writel(SFCTEMP_RSTN, sfctemp->regs);
}

static int sfctemp_enable(struct sfctemp *sfctemp)
{
        int ret;

        if (sfctemp->enabled)
                return 0;

        ret = clk_prepare_enable(sfctemp->clk_bus);
        if (ret)
                return ret;
        ret = reset_control_deassert(sfctemp->rst_bus);
        if (ret)
                goto err_disable_bus;

        ret = clk_prepare_enable(sfctemp->clk_sense);
        if (ret)
                goto err_assert_bus;
        ret = reset_control_deassert(sfctemp->rst_sense);
        if (ret)
                goto err_disable_sense;

        sfctemp_power_up(sfctemp);
        sfctemp_run(sfctemp);
        sfctemp->enabled = true;
        return 0;

err_disable_sense:
        clk_disable_unprepare(sfctemp->clk_sense);
err_assert_bus:
        reset_control_assert(sfctemp->rst_bus);
err_disable_bus:
        clk_disable_unprepare(sfctemp->clk_bus);
        return ret;
}

static int sfctemp_disable(struct sfctemp *sfctemp)
{
        if (!sfctemp->enabled)
                return 0;

        sfctemp_stop(sfctemp);
        sfctemp_power_down(sfctemp);
        reset_control_assert(sfctemp->rst_sense);
        clk_disable_unprepare(sfctemp->clk_sense);
        reset_control_assert(sfctemp->rst_bus);
        clk_disable_unprepare(sfctemp->clk_bus);
        sfctemp->enabled = false;
        return 0;
}

static void sfctemp_disable_action(void *data)
{
        sfctemp_disable(data);
}

static int sfctemp_convert(struct sfctemp *sfctemp, long *val)
{
        if (!sfctemp->enabled)
                return -ENODATA;

        /* calculate temperature in milli Celcius */
        *val = (long)((readl(sfctemp->regs) & SFCTEMP_DOUT_MSK) >> SFCTEMP_DOUT_POS)
                * SFCTEMP_Y1000 / SFCTEMP_Z - SFCTEMP_K1000;

        return 0;
}

static umode_t sfctemp_is_visible(const void *data, enum hwmon_sensor_types type,
                                  u32 attr, int channel)
{
        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_enable:
                        return 0644;
                case hwmon_temp_input:
                        return 0444;
                default:
                        return 0;
                }
        default:
                return 0;
        }
}

static int sfctemp_read(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long *val)
{
        struct sfctemp *sfctemp = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_enable:
                        *val = sfctemp->enabled;
                        return 0;
                case hwmon_temp_input:
                        return sfctemp_convert(sfctemp, val);
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static int sfctemp_write(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long val)
{
        struct sfctemp *sfctemp = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_enable:
                        if (val == 0)
                                return sfctemp_disable(sfctemp);
                        if (val == 1)
                                return sfctemp_enable(sfctemp);
                        return -EINVAL;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const struct hwmon_channel_info *sfctemp_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT),
        NULL
};

static const struct hwmon_ops sfctemp_hwmon_ops = {
        .is_visible = sfctemp_is_visible,
        .read = sfctemp_read,
        .write = sfctemp_write,
};

static const struct hwmon_chip_info sfctemp_chip_info = {
        .ops = &sfctemp_hwmon_ops,
        .info = sfctemp_info,
};

static int sfctemp_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device *hwmon_dev;
        struct sfctemp *sfctemp;
        int ret;

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

        dev_set_drvdata(dev, sfctemp);

        sfctemp->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(sfctemp->regs))
                return PTR_ERR(sfctemp->regs);

        sfctemp->clk_sense = devm_clk_get(dev, "sense");
        if (IS_ERR(sfctemp->clk_sense))
                return dev_err_probe(dev, PTR_ERR(sfctemp->clk_sense),
                                     "error getting sense clock\n");

        sfctemp->clk_bus = devm_clk_get(dev, "bus");
        if (IS_ERR(sfctemp->clk_bus))
                return dev_err_probe(dev, PTR_ERR(sfctemp->clk_bus),
                                     "error getting bus clock\n");

        sfctemp->rst_sense = devm_reset_control_get_exclusive(dev, "sense");
        if (IS_ERR(sfctemp->rst_sense))
                return dev_err_probe(dev, PTR_ERR(sfctemp->rst_sense),
                                     "error getting sense reset\n");

        sfctemp->rst_bus = devm_reset_control_get_exclusive(dev, "bus");
        if (IS_ERR(sfctemp->rst_bus))
                return dev_err_probe(dev, PTR_ERR(sfctemp->rst_bus),
                                     "error getting busreset\n");

        ret = reset_control_assert(sfctemp->rst_sense);
        if (ret)
                return dev_err_probe(dev, ret, "error asserting sense reset\n");

        ret = reset_control_assert(sfctemp->rst_bus);
        if (ret)
                return dev_err_probe(dev, ret, "error asserting bus reset\n");

        ret = devm_add_action(dev, sfctemp_disable_action, sfctemp);
        if (ret)
                return ret;

        ret = sfctemp_enable(sfctemp);
        if (ret)
                return dev_err_probe(dev, ret, "error enabling temperature sensor\n");

        hwmon_dev = devm_hwmon_device_register_with_info(dev, "sfctemp", sfctemp,
                                                         &sfctemp_chip_info, NULL);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct of_device_id sfctemp_of_match[] = {
        { .compatible = "starfive,jh7100-temp" },
        { .compatible = "starfive,jh7110-temp" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sfctemp_of_match);

static struct platform_driver sfctemp_driver = {
        .probe  = sfctemp_probe,
        .driver = {
                .name = "sfctemp",
                .of_match_table = sfctemp_of_match,
        },
};
module_platform_driver(sfctemp_driver);

MODULE_AUTHOR("Emil Renner Berthing");
MODULE_DESCRIPTION("StarFive JH71x0 temperature sensor driver");
MODULE_LICENSE("GPL");