// SPDX-License-Identifier: GPL-2.0
/*
 * Renesas RZ/G2L TSU Thermal Sensor Driver
 *
 * Copyright (C) 2021 Renesas Electronics Corporation
 */
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/thermal.h>
#include <linux/units.h>

#include "thermal_hwmon.h"

#define CTEMP_MASK      0xFFF

/* default calibration values, if FUSE values are missing */
#define SW_CALIB0_VAL   3148
#define SW_CALIB1_VAL   503

/* Register offsets */
#define TSU_SM          0x00
#define TSU_ST          0x04
#define TSU_SAD         0x0C
#define TSU_SS          0x10

#define OTPTSUTRIM_REG(n)       (0x18 + ((n) * 0x4))

/* Sensor Mode Register(TSU_SM) */
#define TSU_SM_EN_TS            BIT(0)
#define TSU_SM_ADC_EN_TS        BIT(1)
#define TSU_SM_NORMAL_MODE      (TSU_SM_EN_TS | TSU_SM_ADC_EN_TS)

/* TSU_ST bits */
#define TSU_ST_START            BIT(0)

#define TSU_SS_CONV_RUNNING     BIT(0)

#define TS_CODE_AVE_SCALE(x)    ((x) * 1000000)
#define MCELSIUS(temp)          ((temp) * MILLIDEGREE_PER_DEGREE)
#define TS_CODE_CAP_TIMES       8       /* Capture  times */

#define RZG2L_THERMAL_GRAN      500     /* milli Celsius */
#define RZG2L_TSU_SS_TIMEOUT_US 1000

#define CURVATURE_CORRECTION_CONST      13

struct rzg2l_thermal_priv {
        struct device *dev;
        void __iomem *base;
        struct thermal_zone_device *zone;
        struct reset_control *rstc;
        u32 calib0, calib1;
};

static inline u32 rzg2l_thermal_read(struct rzg2l_thermal_priv *priv, u32 reg)
{
        return ioread32(priv->base + reg);
}

static inline void rzg2l_thermal_write(struct rzg2l_thermal_priv *priv, u32 reg,
                                       u32 data)
{
        iowrite32(data, priv->base + reg);
}

static int rzg2l_thermal_get_temp(void *devdata, int *temp)
{
        struct rzg2l_thermal_priv *priv = devdata;
        u32 result = 0, dsensor, ts_code_ave;
        int val, i;

        for (i = 0; i < TS_CODE_CAP_TIMES ; i++) {
                /* TSU repeats measurement at 20 microseconds intervals and
                 * automatically updates the results of measurement. As per
                 * the HW manual for measuring temperature we need to read 8
                 * values consecutively and then take the average.
                 * ts_code_ave = (ts_code[0] + ⋯ + ts_code[7]) / 8
                 */
                result += rzg2l_thermal_read(priv, TSU_SAD) & CTEMP_MASK;
                usleep_range(20, 30);
        }

        ts_code_ave = result / TS_CODE_CAP_TIMES;

        /* Calculate actual sensor value by applying curvature correction formula
         * dsensor = ts_code_ave / (1 + ts_code_ave * 0.000013). Here we are doing
         * integer calculation by scaling all the values by 1000000.
         */
        dsensor = TS_CODE_AVE_SCALE(ts_code_ave) /
                (TS_CODE_AVE_SCALE(1) + (ts_code_ave * CURVATURE_CORRECTION_CONST));

        /* The temperature Tj is calculated by the formula
         * Tj = (dsensor − calib1) * 165/ (calib0 − calib1) − 40
         * where calib0 and calib1 are the caliberation values.
         */
        val = ((dsensor - priv->calib1) * (MCELSIUS(165) /
                (priv->calib0 - priv->calib1))) - MCELSIUS(40);

        *temp = roundup(val, RZG2L_THERMAL_GRAN);

        return 0;
}

static const struct thermal_zone_of_device_ops rzg2l_tz_of_ops = {
        .get_temp = rzg2l_thermal_get_temp,
};

static int rzg2l_thermal_init(struct rzg2l_thermal_priv *priv)
{
        u32 reg_val;

        rzg2l_thermal_write(priv, TSU_SM, TSU_SM_NORMAL_MODE);
        rzg2l_thermal_write(priv, TSU_ST, 0);

        /* Before setting the START bit, TSU should be in normal operating
         * mode. As per the HW manual, it will take 60 µs to place the TSU
         * into normal operating mode.
         */
        usleep_range(60, 80);

        reg_val = rzg2l_thermal_read(priv, TSU_ST);
        reg_val |= TSU_ST_START;
        rzg2l_thermal_write(priv, TSU_ST, reg_val);

        return readl_poll_timeout(priv->base + TSU_SS, reg_val,
                                  reg_val == TSU_SS_CONV_RUNNING, 50,
                                  RZG2L_TSU_SS_TIMEOUT_US);
}

static void rzg2l_thermal_reset_assert_pm_disable_put(struct platform_device *pdev)
{
        struct rzg2l_thermal_priv *priv = dev_get_drvdata(&pdev->dev);

        pm_runtime_put(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
        reset_control_assert(priv->rstc);
}

static int rzg2l_thermal_remove(struct platform_device *pdev)
{
        struct rzg2l_thermal_priv *priv = dev_get_drvdata(&pdev->dev);

        thermal_remove_hwmon_sysfs(priv->zone);
        rzg2l_thermal_reset_assert_pm_disable_put(pdev);

        return 0;
}

static int rzg2l_thermal_probe(struct platform_device *pdev)
{
        struct thermal_zone_device *zone;
        struct rzg2l_thermal_priv *priv;
        struct device *dev = &pdev->dev;
        int ret;

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

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

        priv->dev = dev;
        priv->rstc = devm_reset_control_get_exclusive(dev, NULL);
        if (IS_ERR(priv->rstc))
                return dev_err_probe(dev, PTR_ERR(priv->rstc),
                                     "failed to get cpg reset");

        ret = reset_control_deassert(priv->rstc);
        if (ret)
                return dev_err_probe(dev, ret, "failed to deassert");

        pm_runtime_enable(dev);
        pm_runtime_get_sync(dev);

        priv->calib0 = rzg2l_thermal_read(priv, OTPTSUTRIM_REG(0));
        if (!priv->calib0)
                priv->calib0 = SW_CALIB0_VAL;

        priv->calib1 = rzg2l_thermal_read(priv, OTPTSUTRIM_REG(1));
        if (!priv->calib1)
                priv->calib1 = SW_CALIB1_VAL;

        platform_set_drvdata(pdev, priv);
        ret = rzg2l_thermal_init(priv);
        if (ret) {
                dev_err(dev, "Failed to start TSU");
                goto err;
        }

        zone = devm_thermal_zone_of_sensor_register(dev, 0, priv,
                                                    &rzg2l_tz_of_ops);
        if (IS_ERR(zone)) {
                dev_err(dev, "Can't register thermal zone");
                ret = PTR_ERR(zone);
                goto err;
        }

        priv->zone = zone;
        priv->zone->tzp->no_hwmon = false;
        ret = thermal_add_hwmon_sysfs(priv->zone);
        if (ret)
                goto err;

        dev_dbg(dev, "TSU probed with %s caliberation values",
                rzg2l_thermal_read(priv, OTPTSUTRIM_REG(0)) ?  "hw" : "sw");

        return 0;

err:
        rzg2l_thermal_reset_assert_pm_disable_put(pdev);
        return ret;
}

static const struct of_device_id rzg2l_thermal_dt_ids[] = {
        { .compatible = "renesas,rzg2l-tsu", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rzg2l_thermal_dt_ids);

static struct platform_driver rzg2l_thermal_driver = {
        .driver = {
                .name = "rzg2l_thermal",
                .of_match_table = rzg2l_thermal_dt_ids,
        },
        .probe = rzg2l_thermal_probe,
        .remove = rzg2l_thermal_remove,
};
module_platform_driver(rzg2l_thermal_driver);

MODULE_DESCRIPTION("Renesas RZ/G2L TSU Thermal Sensor Driver");
MODULE_AUTHOR("Biju Das <biju.das.jz@bp.renesas.com>");
MODULE_LICENSE("GPL v2");