// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
 * Author: David Hernandez Sanchez <david.hernandezsanchez@st.com> for
 * STMicroelectronics.
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/thermal.h>
#include <linux/units.h>

#include "../thermal_hwmon.h"

/* DTS register offsets */
#define DTS_CFGR1_OFFSET        0x0
#define DTS_T0VALR1_OFFSET      0x8
#define DTS_RAMPVALR_OFFSET     0X10
#define DTS_ITR1_OFFSET         0x14
#define DTS_DR_OFFSET           0x1C
#define DTS_SR_OFFSET           0x20
#define DTS_ITENR_OFFSET        0x24
#define DTS_ICIFR_OFFSET        0x28

/* DTS_CFGR1 register mask definitions */
#define HSREF_CLK_DIV_MASK      GENMASK(30, 24)
#define TS1_SMP_TIME_MASK       GENMASK(19, 16)
#define TS1_INTRIG_SEL_MASK     GENMASK(11, 8)

/* DTS_T0VALR1 register mask definitions */
#define TS1_T0_MASK             GENMASK(17, 16)
#define TS1_FMT0_MASK           GENMASK(15, 0)

/* DTS_RAMPVALR register mask definitions */
#define TS1_RAMP_COEFF_MASK     GENMASK(15, 0)

/* DTS_ITR1 register mask definitions */
#define TS1_HITTHD_MASK         GENMASK(31, 16)
#define TS1_LITTHD_MASK         GENMASK(15, 0)

/* DTS_DR register mask definitions */
#define TS1_MFREQ_MASK          GENMASK(15, 0)

/* DTS_ITENR register mask definitions */
#define ITENR_MASK              (GENMASK(2, 0) | GENMASK(6, 4))

/* DTS_ICIFR register mask definitions */
#define ICIFR_MASK              (GENMASK(2, 0) | GENMASK(6, 4))

/* Less significant bit position definitions */
#define TS1_T0_POS              16
#define TS1_HITTHD_POS          16
#define TS1_LITTHD_POS          0
#define HSREF_CLK_DIV_POS       24

/* DTS_CFGR1 bit definitions */
#define TS1_EN                  BIT(0)
#define TS1_START               BIT(4)
#define REFCLK_SEL              BIT(20)
#define REFCLK_LSE              REFCLK_SEL
#define Q_MEAS_OPT              BIT(21)
#define CALIBRATION_CONTROL     Q_MEAS_OPT

/* DTS_SR bit definitions */
#define TS_RDY                  BIT(15)
/* Bit definitions below are common for DTS_SR, DTS_ITENR and DTS_CIFR */
#define HIGH_THRESHOLD          BIT(2)
#define LOW_THRESHOLD           BIT(1)

/* Constants */
#define ADJUST                  100
#define POLL_TIMEOUT            5000
#define STARTUP_TIME            40
#define TS1_T0_VAL0             30000  /* 30 celsius */
#define TS1_T0_VAL1             130000 /* 130 celsius */
#define NO_HW_TRIG              0
#define SAMPLING_TIME           15

struct stm_thermal_sensor {
        struct device *dev;
        struct thermal_zone_device *th_dev;
        enum thermal_device_mode mode;
        struct clk *clk;
        unsigned int low_temp_enabled;
        unsigned int high_temp_enabled;
        int irq;
        void __iomem *base;
        int t0, fmt0, ramp_coeff;
};

static int stm_enable_irq(struct stm_thermal_sensor *sensor)
{
        u32 value;

        dev_dbg(sensor->dev, "low:%d high:%d\n", sensor->low_temp_enabled,
                sensor->high_temp_enabled);

        /* Disable IT generation for low and high thresholds */
        value = readl_relaxed(sensor->base + DTS_ITENR_OFFSET);
        value &= ~(LOW_THRESHOLD | HIGH_THRESHOLD);

        if (sensor->low_temp_enabled)
                value |= HIGH_THRESHOLD;

        if (sensor->high_temp_enabled)
                value |= LOW_THRESHOLD;

        /* Enable interrupts */
        writel_relaxed(value, sensor->base + DTS_ITENR_OFFSET);

        return 0;
}

static irqreturn_t stm_thermal_irq_handler(int irq, void *sdata)
{
        struct stm_thermal_sensor *sensor = sdata;

        dev_dbg(sensor->dev, "sr:%d\n",
                readl_relaxed(sensor->base + DTS_SR_OFFSET));

        thermal_zone_device_update(sensor->th_dev, THERMAL_EVENT_UNSPECIFIED);

        stm_enable_irq(sensor);

        /* Acknoledge all DTS irqs */
        writel_relaxed(ICIFR_MASK, sensor->base + DTS_ICIFR_OFFSET);

        return IRQ_HANDLED;
}

static int stm_sensor_power_on(struct stm_thermal_sensor *sensor)
{
        int ret;
        u32 value;

        /* Enable sensor */
        value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
        value |= TS1_EN;
        writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);

        /*
         * The DTS block can be enabled by setting TSx_EN bit in
         * DTS_CFGRx register. It requires a startup time of
         * 40μs. Use 5 ms as arbitrary timeout.
         */
        ret = readl_poll_timeout(sensor->base + DTS_SR_OFFSET,
                                 value, (value & TS_RDY),
                                 STARTUP_TIME, POLL_TIMEOUT);
        if (ret)
                return ret;

        /* Start continuous measuring */
        value = readl_relaxed(sensor->base +
                              DTS_CFGR1_OFFSET);
        value |= TS1_START;
        writel_relaxed(value, sensor->base +
                       DTS_CFGR1_OFFSET);

        sensor->mode = THERMAL_DEVICE_ENABLED;

        return 0;
}

static int stm_sensor_power_off(struct stm_thermal_sensor *sensor)
{
        u32 value;

        sensor->mode = THERMAL_DEVICE_DISABLED;

        /* Stop measuring */
        value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
        value &= ~TS1_START;
        writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);

        /* Ensure stop is taken into account */
        usleep_range(STARTUP_TIME, POLL_TIMEOUT);

        /* Disable sensor */
        value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
        value &= ~TS1_EN;
        writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);

        /* Ensure disable is taken into account */
        return readl_poll_timeout(sensor->base + DTS_SR_OFFSET, value,
                                  !(value & TS_RDY),
                                  STARTUP_TIME, POLL_TIMEOUT);
}

static int stm_thermal_calibration(struct stm_thermal_sensor *sensor)
{
        u32 value, clk_freq;
        u32 prescaler;

        /* Figure out prescaler value for PCLK during calibration */
        clk_freq = clk_get_rate(sensor->clk);
        if (!clk_freq)
                return -EINVAL;

        prescaler = 0;
        clk_freq /= HZ_PER_MHZ;
        if (clk_freq) {
                while (prescaler <= clk_freq)
                        prescaler++;
        }

        value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);

        /* Clear prescaler */
        value &= ~HSREF_CLK_DIV_MASK;

        /* Set prescaler. pclk_freq/prescaler < 1MHz */
        value |= (prescaler << HSREF_CLK_DIV_POS);

        /* Select PCLK as reference clock */
        value &= ~REFCLK_SEL;

        /* Set maximal sampling time for better precision */
        value |= TS1_SMP_TIME_MASK;

        /* Measure with calibration */
        value &= ~CALIBRATION_CONTROL;

        /* select trigger */
        value &= ~TS1_INTRIG_SEL_MASK;
        value |= NO_HW_TRIG;

        writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);

        return 0;
}

/* Fill in DTS structure with factory sensor values */
static int stm_thermal_read_factory_settings(struct stm_thermal_sensor *sensor)
{
        /* Retrieve engineering calibration temperature */
        sensor->t0 = readl_relaxed(sensor->base + DTS_T0VALR1_OFFSET) &
                                        TS1_T0_MASK;
        if (!sensor->t0)
                sensor->t0 = TS1_T0_VAL0;
        else
                sensor->t0 = TS1_T0_VAL1;

        /* Retrieve fmt0 and put it on Hz */
        sensor->fmt0 = ADJUST * (readl_relaxed(sensor->base +
                                 DTS_T0VALR1_OFFSET) & TS1_FMT0_MASK);

        /* Retrieve ramp coefficient */
        sensor->ramp_coeff = readl_relaxed(sensor->base + DTS_RAMPVALR_OFFSET) &
                                           TS1_RAMP_COEFF_MASK;

        if (!sensor->fmt0 || !sensor->ramp_coeff) {
                dev_err(sensor->dev, "%s: wrong setting\n", __func__);
                return -EINVAL;
        }

        dev_dbg(sensor->dev, "%s: T0 = %doC, FMT0 = %dHz, RAMP_COEFF = %dHz/oC",
                __func__, sensor->t0, sensor->fmt0, sensor->ramp_coeff);

        return 0;
}

static int stm_thermal_calculate_threshold(struct stm_thermal_sensor *sensor,
                                           int temp, u32 *th)
{
        int freqM;

        /* Figure out the CLK_PTAT frequency for a given temperature */
        freqM = ((temp - sensor->t0) * sensor->ramp_coeff) / 1000 +
                sensor->fmt0;

        /* Figure out the threshold sample number */
        *th = clk_get_rate(sensor->clk) * SAMPLING_TIME / freqM;
        if (!*th)
                return -EINVAL;

        dev_dbg(sensor->dev, "freqM=%d Hz, threshold=0x%x", freqM, *th);

        return 0;
}

/* Disable temperature interrupt */
static int stm_disable_irq(struct stm_thermal_sensor *sensor)
{
        u32 value;

        /* Disable IT generation */
        value = readl_relaxed(sensor->base + DTS_ITENR_OFFSET);
        value &= ~ITENR_MASK;
        writel_relaxed(value, sensor->base + DTS_ITENR_OFFSET);

        return 0;
}

static int stm_thermal_set_trips(struct thermal_zone_device *tz, int low, int high)
{
        struct stm_thermal_sensor *sensor = thermal_zone_device_priv(tz);
        u32 itr1, th;
        int ret;

        dev_dbg(sensor->dev, "set trips %d <--> %d\n", low, high);

        /* Erase threshold content */
        itr1 = readl_relaxed(sensor->base + DTS_ITR1_OFFSET);
        itr1 &= ~(TS1_LITTHD_MASK | TS1_HITTHD_MASK);

        /*
         * Disable low-temp if "low" is too small. As per thermal framework
         * API, we use -INT_MAX rather than INT_MIN.
         */

        if (low > -INT_MAX) {
                sensor->low_temp_enabled = 1;
                /* add 0.5 of hysteresis due to measurement error */
                ret = stm_thermal_calculate_threshold(sensor, low - 500, &th);
                if (ret)
                        return ret;

                itr1 |= (TS1_HITTHD_MASK  & (th << TS1_HITTHD_POS));
        } else {
                sensor->low_temp_enabled = 0;
        }

        /* Disable high-temp if "high" is too big. */
        if (high < INT_MAX) {
                sensor->high_temp_enabled = 1;
                ret = stm_thermal_calculate_threshold(sensor, high, &th);
                if (ret)
                        return ret;

                itr1 |= (TS1_LITTHD_MASK  & (th << TS1_LITTHD_POS));
        } else {
                sensor->high_temp_enabled = 0;
        }

        /* Write new threshod values*/
        writel_relaxed(itr1, sensor->base + DTS_ITR1_OFFSET);

        return 0;
}

/* Callback to get temperature from HW */
static int stm_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
{
        struct stm_thermal_sensor *sensor = thermal_zone_device_priv(tz);
        u32 periods;
        int freqM, ret;

        if (sensor->mode != THERMAL_DEVICE_ENABLED)
                return -EAGAIN;

        /* Retrieve the number of periods sampled */
        ret = readl_relaxed_poll_timeout(sensor->base + DTS_DR_OFFSET, periods,
                                         (periods & TS1_MFREQ_MASK),
                                         STARTUP_TIME, POLL_TIMEOUT);
        if (ret)
                return ret;

        /* Figure out the CLK_PTAT frequency */
        freqM = (clk_get_rate(sensor->clk) * SAMPLING_TIME) / periods;
        if (!freqM)
                return -EINVAL;

        /* Figure out the temperature in mili celsius */
        *temp = (freqM - sensor->fmt0) * 1000 / sensor->ramp_coeff + sensor->t0;

        return 0;
}

/* Registers DTS irq to be visible by GIC */
static int stm_register_irq(struct stm_thermal_sensor *sensor)
{
        struct device *dev = sensor->dev;
        struct platform_device *pdev = to_platform_device(dev);
        int ret;

        sensor->irq = platform_get_irq(pdev, 0);
        if (sensor->irq < 0)
                return sensor->irq;

        ret = devm_request_threaded_irq(dev, sensor->irq,
                                        NULL,
                                        stm_thermal_irq_handler,
                                        IRQF_ONESHOT,
                                        dev->driver->name, sensor);
        if (ret) {
                dev_err(dev, "%s: Failed to register IRQ %d\n", __func__,
                        sensor->irq);
                return ret;
        }

        dev_dbg(dev, "%s: thermal IRQ registered", __func__);

        return 0;
}

static int stm_thermal_sensor_off(struct stm_thermal_sensor *sensor)
{
        int ret;

        stm_disable_irq(sensor);

        ret = stm_sensor_power_off(sensor);
        if (ret)
                return ret;

        clk_disable_unprepare(sensor->clk);

        return 0;
}

static int stm_thermal_prepare(struct stm_thermal_sensor *sensor)
{
        int ret;

        ret = clk_prepare_enable(sensor->clk);
        if (ret)
                return ret;

        ret = stm_thermal_read_factory_settings(sensor);
        if (ret)
                goto thermal_unprepare;

        ret = stm_thermal_calibration(sensor);
        if (ret)
                goto thermal_unprepare;

        return 0;

thermal_unprepare:
        clk_disable_unprepare(sensor->clk);

        return ret;
}

static int stm_thermal_suspend(struct device *dev)
{
        struct stm_thermal_sensor *sensor = dev_get_drvdata(dev);

        return stm_thermal_sensor_off(sensor);
}

static int stm_thermal_resume(struct device *dev)
{
        int ret;
        struct stm_thermal_sensor *sensor = dev_get_drvdata(dev);

        ret = stm_thermal_prepare(sensor);
        if (ret)
                return ret;

        ret = stm_sensor_power_on(sensor);
        if (ret)
                return ret;

        thermal_zone_device_update(sensor->th_dev, THERMAL_EVENT_UNSPECIFIED);
        stm_enable_irq(sensor);

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(stm_thermal_pm_ops,
                                stm_thermal_suspend, stm_thermal_resume);

static const struct thermal_zone_device_ops stm_tz_ops = {
        .get_temp       = stm_thermal_get_temp,
        .set_trips      = stm_thermal_set_trips,
};

static const struct of_device_id stm_thermal_of_match[] = {
                { .compatible = "st,stm32-thermal"},
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, stm_thermal_of_match);

static int stm_thermal_probe(struct platform_device *pdev)
{
        struct stm_thermal_sensor *sensor;
        void __iomem *base;
        int ret;

        if (!pdev->dev.of_node) {
                dev_err(&pdev->dev, "%s: device tree node not found\n",
                        __func__);
                return -EINVAL;
        }

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

        platform_set_drvdata(pdev, sensor);

        sensor->dev = &pdev->dev;

        base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
        if (IS_ERR(base))
                return PTR_ERR(base);

        /* Populate sensor */
        sensor->base = base;

        sensor->clk = devm_clk_get(&pdev->dev, "pclk");
        if (IS_ERR(sensor->clk)) {
                dev_err(&pdev->dev, "%s: failed to fetch PCLK clock\n",
                        __func__);
                return PTR_ERR(sensor->clk);
        }

        stm_disable_irq(sensor);

        /* Clear irq flags */
        writel_relaxed(ICIFR_MASK, sensor->base + DTS_ICIFR_OFFSET);

        /* Configure and enable HW sensor */
        ret = stm_thermal_prepare(sensor);
        if (ret) {
                dev_err(&pdev->dev, "Error prepare sensor: %d\n", ret);
                return ret;
        }

        ret = stm_sensor_power_on(sensor);
        if (ret) {
                dev_err(&pdev->dev, "Error power on sensor: %d\n", ret);
                return ret;
        }

        sensor->th_dev = devm_thermal_of_zone_register(&pdev->dev, 0,
                                                       sensor,
                                                       &stm_tz_ops);

        if (IS_ERR(sensor->th_dev)) {
                dev_err(&pdev->dev, "%s: thermal zone sensor registering KO\n",
                        __func__);
                ret = PTR_ERR(sensor->th_dev);
                return ret;
        }

        /* Register IRQ into GIC */
        ret = stm_register_irq(sensor);
        if (ret)
                goto err_tz;

        stm_enable_irq(sensor);

        /*
         * Thermal_zone doesn't enable hwmon as default,
         * enable it here
         */
        ret = thermal_add_hwmon_sysfs(sensor->th_dev);
        if (ret)
                goto err_tz;

        dev_info(&pdev->dev, "%s: Driver initialized successfully\n",
                 __func__);

        return 0;

err_tz:
        return ret;
}

static void stm_thermal_remove(struct platform_device *pdev)
{
        struct stm_thermal_sensor *sensor = platform_get_drvdata(pdev);

        stm_thermal_sensor_off(sensor);
        thermal_remove_hwmon_sysfs(sensor->th_dev);
}

static struct platform_driver stm_thermal_driver = {
        .driver = {
                .name   = "stm_thermal",
                .pm     = pm_sleep_ptr(&stm_thermal_pm_ops),
                .of_match_table = stm_thermal_of_match,
        },
        .probe          = stm_thermal_probe,
        .remove         = stm_thermal_remove,
};
module_platform_driver(stm_thermal_driver);

MODULE_DESCRIPTION("STMicroelectronics STM32 Thermal Sensor Driver");
MODULE_AUTHOR("David Hernandez Sanchez <david.hernandezsanchez@st.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:stm_thermal");