// 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/mod_devicetable.h>
#include <linux/module.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))
#define OTPTSUTRIM_EN_MASK	BIT(31)
#define OTPTSUTRIM_MASK		GENMASK(11, 0)

/* 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	/* Total number of ADC data samples */

#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(struct thermal_zone_device *tz, int *temp)
{
	struct rzg2l_thermal_priv *priv = thermal_zone_device_priv(tz);
	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 calibration 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_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 void 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);
}

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 & OTPTSUTRIM_EN_MASK)
		priv->calib0 &= OTPTSUTRIM_MASK;
	else
		priv->calib0 = SW_CALIB0_VAL;

	priv->calib1 = rzg2l_thermal_read(priv, OTPTSUTRIM_REG(1));
	if (priv->calib1 & OTPTSUTRIM_EN_MASK)
		priv->calib1 &= OTPTSUTRIM_MASK;
	else
		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_of_zone_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;
	ret = thermal_add_hwmon_sysfs(priv->zone);
	if (ret)
		goto err;

	dev_dbg(dev, "TSU probed with %s calibration 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_new = 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");