/*
 * Copyright 2013 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/clk.h>
#include <linux/cpu_cooling.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/thermal.h>
#include <linux/types.h>

#define REG_SET         0x4
#define REG_CLR         0x8
#define REG_TOG         0xc

#define MISC0                           0x0150
#define MISC0_REFTOP_SELBIASOFF         (1 << 3)

#define TEMPSENSE0                      0x0180
#define TEMPSENSE0_ALARM_VALUE_SHIFT    20
#define TEMPSENSE0_ALARM_VALUE_MASK     (0xfff << TEMPSENSE0_ALARM_VALUE_SHIFT)
#define TEMPSENSE0_TEMP_CNT_SHIFT       8
#define TEMPSENSE0_TEMP_CNT_MASK        (0xfff << TEMPSENSE0_TEMP_CNT_SHIFT)
#define TEMPSENSE0_FINISHED             (1 << 2)
#define TEMPSENSE0_MEASURE_TEMP         (1 << 1)
#define TEMPSENSE0_POWER_DOWN           (1 << 0)

#define TEMPSENSE1                      0x0190
#define TEMPSENSE1_MEASURE_FREQ         0xffff

#define OCOTP_ANA1                      0x04e0

/* The driver supports 1 passive trip point and 1 critical trip point */
enum imx_thermal_trip {
        IMX_TRIP_PASSIVE,
        IMX_TRIP_CRITICAL,
        IMX_TRIP_NUM,
};

/*
 * It defines the temperature in millicelsius for passive trip point
 * that will trigger cooling action when crossed.
 */
#define IMX_TEMP_PASSIVE                85000

#define IMX_POLLING_DELAY               2000 /* millisecond */
#define IMX_PASSIVE_DELAY               1000

struct imx_thermal_data {
        struct thermal_zone_device *tz;
        struct thermal_cooling_device *cdev;
        enum thermal_device_mode mode;
        struct regmap *tempmon;
        int c1, c2; /* See formula in imx_get_sensor_data() */
        unsigned long temp_passive;
        unsigned long temp_critical;
        unsigned long alarm_temp;
        unsigned long last_temp;
        bool irq_enabled;
        int irq;
        struct clk *thermal_clk;
};

static void imx_set_alarm_temp(struct imx_thermal_data *data,
                               signed long alarm_temp)
{
        struct regmap *map = data->tempmon;
        int alarm_value;

        data->alarm_temp = alarm_temp;
        alarm_value = (alarm_temp - data->c2) / data->c1;
        regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_ALARM_VALUE_MASK);
        regmap_write(map, TEMPSENSE0 + REG_SET, alarm_value <<
                        TEMPSENSE0_ALARM_VALUE_SHIFT);
}

static int imx_get_temp(struct thermal_zone_device *tz, unsigned long *temp)
{
        struct imx_thermal_data *data = tz->devdata;
        struct regmap *map = data->tempmon;
        unsigned int n_meas;
        bool wait;
        u32 val;

        if (data->mode == THERMAL_DEVICE_ENABLED) {
                /* Check if a measurement is currently in progress */
                regmap_read(map, TEMPSENSE0, &val);
                wait = !(val & TEMPSENSE0_FINISHED);
        } else {
                /*
                 * Every time we measure the temperature, we will power on the
                 * temperature sensor, enable measurements, take a reading,
                 * disable measurements, power off the temperature sensor.
                 */
                regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
                regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);

                wait = true;
        }

        /*
         * According to the temp sensor designers, it may require up to ~17us
         * to complete a measurement.
         */
        if (wait)
                usleep_range(20, 50);

        regmap_read(map, TEMPSENSE0, &val);

        if (data->mode != THERMAL_DEVICE_ENABLED) {
                regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
                regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
        }

        if ((val & TEMPSENSE0_FINISHED) == 0) {
                dev_dbg(&tz->device, "temp measurement never finished\n");
                return -EAGAIN;
        }

        n_meas = (val & TEMPSENSE0_TEMP_CNT_MASK) >> TEMPSENSE0_TEMP_CNT_SHIFT;

        /* See imx_get_sensor_data() for formula derivation */
        *temp = data->c2 + data->c1 * n_meas;

        /* Update alarm value to next higher trip point */
        if (data->alarm_temp == data->temp_passive && *temp >= data->temp_passive)
                imx_set_alarm_temp(data, data->temp_critical);
        if (data->alarm_temp == data->temp_critical && *temp < data->temp_passive) {
                imx_set_alarm_temp(data, data->temp_passive);
                dev_dbg(&tz->device, "thermal alarm off: T < %lu\n",
                        data->alarm_temp / 1000);
        }

        if (*temp != data->last_temp) {
                dev_dbg(&tz->device, "millicelsius: %ld\n", *temp);
                data->last_temp = *temp;
        }

        /* Reenable alarm IRQ if temperature below alarm temperature */
        if (!data->irq_enabled && *temp < data->alarm_temp) {
                data->irq_enabled = true;
                enable_irq(data->irq);
        }

        return 0;
}

static int imx_get_mode(struct thermal_zone_device *tz,
                        enum thermal_device_mode *mode)
{
        struct imx_thermal_data *data = tz->devdata;

        *mode = data->mode;

        return 0;
}

static int imx_set_mode(struct thermal_zone_device *tz,
                        enum thermal_device_mode mode)
{
        struct imx_thermal_data *data = tz->devdata;
        struct regmap *map = data->tempmon;

        if (mode == THERMAL_DEVICE_ENABLED) {
                tz->polling_delay = IMX_POLLING_DELAY;
                tz->passive_delay = IMX_PASSIVE_DELAY;

                regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
                regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);

                if (!data->irq_enabled) {
                        data->irq_enabled = true;
                        enable_irq(data->irq);
                }
        } else {
                regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
                regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);

                tz->polling_delay = 0;
                tz->passive_delay = 0;

                if (data->irq_enabled) {
                        disable_irq(data->irq);
                        data->irq_enabled = false;
                }
        }

        data->mode = mode;
        thermal_zone_device_update(tz);

        return 0;
}

static int imx_get_trip_type(struct thermal_zone_device *tz, int trip,
                             enum thermal_trip_type *type)
{
        *type = (trip == IMX_TRIP_PASSIVE) ? THERMAL_TRIP_PASSIVE :
                                             THERMAL_TRIP_CRITICAL;
        return 0;
}

static int imx_get_crit_temp(struct thermal_zone_device *tz,
                             unsigned long *temp)
{
        struct imx_thermal_data *data = tz->devdata;

        *temp = data->temp_critical;
        return 0;
}

static int imx_get_trip_temp(struct thermal_zone_device *tz, int trip,
                             unsigned long *temp)
{
        struct imx_thermal_data *data = tz->devdata;

        *temp = (trip == IMX_TRIP_PASSIVE) ? data->temp_passive :
                                             data->temp_critical;
        return 0;
}

static int imx_set_trip_temp(struct thermal_zone_device *tz, int trip,
                             unsigned long temp)
{
        struct imx_thermal_data *data = tz->devdata;

        if (trip == IMX_TRIP_CRITICAL)
                return -EPERM;

        if (temp > IMX_TEMP_PASSIVE)
                return -EINVAL;

        data->temp_passive = temp;

        imx_set_alarm_temp(data, temp);

        return 0;
}

static int imx_bind(struct thermal_zone_device *tz,
                    struct thermal_cooling_device *cdev)
{
        int ret;

        ret = thermal_zone_bind_cooling_device(tz, IMX_TRIP_PASSIVE, cdev,
                                               THERMAL_NO_LIMIT,
                                               THERMAL_NO_LIMIT);
        if (ret) {
                dev_err(&tz->device,
                        "binding zone %s with cdev %s failed:%d\n",
                        tz->type, cdev->type, ret);
                return ret;
        }

        return 0;
}

static int imx_unbind(struct thermal_zone_device *tz,
                      struct thermal_cooling_device *cdev)
{
        int ret;

        ret = thermal_zone_unbind_cooling_device(tz, IMX_TRIP_PASSIVE, cdev);
        if (ret) {
                dev_err(&tz->device,
                        "unbinding zone %s with cdev %s failed:%d\n",
                        tz->type, cdev->type, ret);
                return ret;
        }

        return 0;
}

static struct thermal_zone_device_ops imx_tz_ops = {
        .bind = imx_bind,
        .unbind = imx_unbind,
        .get_temp = imx_get_temp,
        .get_mode = imx_get_mode,
        .set_mode = imx_set_mode,
        .get_trip_type = imx_get_trip_type,
        .get_trip_temp = imx_get_trip_temp,
        .get_crit_temp = imx_get_crit_temp,
        .set_trip_temp = imx_set_trip_temp,
};

static int imx_get_sensor_data(struct platform_device *pdev)
{
        struct imx_thermal_data *data = platform_get_drvdata(pdev);
        struct regmap *map;
        int t1, t2, n1, n2;
        int ret;
        u32 val;

        map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
                                              "fsl,tempmon-data");
        if (IS_ERR(map)) {
                ret = PTR_ERR(map);
                dev_err(&pdev->dev, "failed to get sensor regmap: %d\n", ret);
                return ret;
        }

        ret = regmap_read(map, OCOTP_ANA1, &val);
        if (ret) {
                dev_err(&pdev->dev, "failed to read sensor data: %d\n", ret);
                return ret;
        }

        if (val == 0 || val == ~0) {
                dev_err(&pdev->dev, "invalid sensor calibration data\n");
                return -EINVAL;
        }

        /*
         * Sensor data layout:
         *   [31:20] - sensor value @ 25C
         *    [19:8] - sensor value of hot
         *     [7:0] - hot temperature value
         */
        n1 = val >> 20;
        n2 = (val & 0xfff00) >> 8;
        t2 = val & 0xff;
        t1 = 25; /* t1 always 25C */

        /*
         * Derived from linear interpolation,
         * Tmeas = T2 + (Nmeas - N2) * (T1 - T2) / (N1 - N2)
         * We want to reduce this down to the minimum computation necessary
         * for each temperature read.  Also, we want Tmeas in millicelsius
         * and we don't want to lose precision from integer division. So...
         * milli_Tmeas = 1000 * T2 + 1000 * (Nmeas - N2) * (T1 - T2) / (N1 - N2)
         * Let constant c1 = 1000 * (T1 - T2) / (N1 - N2)
         * milli_Tmeas = (1000 * T2) + c1 * (Nmeas - N2)
         * milli_Tmeas = (1000 * T2) + (c1 * Nmeas) - (c1 * N2)
         * Let constant c2 = (1000 * T2) - (c1 * N2)
         * milli_Tmeas = c2 + (c1 * Nmeas)
         */
        data->c1 = 1000 * (t1 - t2) / (n1 - n2);
        data->c2 = 1000 * t2 - data->c1 * n2;

        /*
         * Set the default passive cooling trip point to 20 °C below the
         * maximum die temperature. Can be changed from userspace.
         */
        data->temp_passive = 1000 * (t2 - 20);

        /*
         * The maximum die temperature is t2, let's give 5 °C cushion
         * for noise and possible temperature rise between measurements.
         */
        data->temp_critical = 1000 * (t2 - 5);

        return 0;
}

static irqreturn_t imx_thermal_alarm_irq(int irq, void *dev)
{
        struct imx_thermal_data *data = dev;

        disable_irq_nosync(irq);
        data->irq_enabled = false;

        return IRQ_WAKE_THREAD;
}

static irqreturn_t imx_thermal_alarm_irq_thread(int irq, void *dev)
{
        struct imx_thermal_data *data = dev;

        dev_dbg(&data->tz->device, "THERMAL ALARM: T > %lu\n",
                data->alarm_temp / 1000);

        thermal_zone_device_update(data->tz);

        return IRQ_HANDLED;
}

static int imx_thermal_probe(struct platform_device *pdev)
{
        struct imx_thermal_data *data;
        struct cpumask clip_cpus;
        struct regmap *map;
        int measure_freq;
        int ret;

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

        map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "fsl,tempmon");
        if (IS_ERR(map)) {
                ret = PTR_ERR(map);
                dev_err(&pdev->dev, "failed to get tempmon regmap: %d\n", ret);
                return ret;
        }
        data->tempmon = map;

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

        ret = devm_request_threaded_irq(&pdev->dev, data->irq,
                        imx_thermal_alarm_irq, imx_thermal_alarm_irq_thread,
                        0, "imx_thermal", data);
        if (ret < 0) {
                dev_err(&pdev->dev, "failed to request alarm irq: %d\n", ret);
                return ret;
        }

        platform_set_drvdata(pdev, data);

        ret = imx_get_sensor_data(pdev);
        if (ret) {
                dev_err(&pdev->dev, "failed to get sensor data\n");
                return ret;
        }

        /* Make sure sensor is in known good state for measurements */
        regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
        regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
        regmap_write(map, TEMPSENSE1 + REG_CLR, TEMPSENSE1_MEASURE_FREQ);
        regmap_write(map, MISC0 + REG_SET, MISC0_REFTOP_SELBIASOFF);
        regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);

        cpumask_set_cpu(0, &clip_cpus);
        data->cdev = cpufreq_cooling_register(&clip_cpus);
        if (IS_ERR(data->cdev)) {
                ret = PTR_ERR(data->cdev);
                dev_err(&pdev->dev,
                        "failed to register cpufreq cooling device: %d\n", ret);
                return ret;
        }

        data->tz = thermal_zone_device_register("imx_thermal_zone",
                                                IMX_TRIP_NUM,
                                                BIT(IMX_TRIP_PASSIVE), data,
                                                &imx_tz_ops, NULL,
                                                IMX_PASSIVE_DELAY,
                                                IMX_POLLING_DELAY);
        if (IS_ERR(data->tz)) {
                ret = PTR_ERR(data->tz);
                dev_err(&pdev->dev,
                        "failed to register thermal zone device %d\n", ret);
                cpufreq_cooling_unregister(data->cdev);
                return ret;
        }

        data->thermal_clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(data->thermal_clk)) {
                dev_warn(&pdev->dev, "failed to get thermal clk!\n");
        } else {
                /*
                 * Thermal sensor needs clk on to get correct value, normally
                 * we should enable its clk before taking measurement and disable
                 * clk after measurement is done, but if alarm function is enabled,
                 * hardware will auto measure the temperature periodically, so we
                 * need to keep the clk always on for alarm function.
                 */
                ret = clk_prepare_enable(data->thermal_clk);
                if (ret)
                        dev_warn(&pdev->dev, "failed to enable thermal clk: %d\n", ret);
        }

        /* Enable measurements at ~ 10 Hz */
        regmap_write(map, TEMPSENSE1 + REG_CLR, TEMPSENSE1_MEASURE_FREQ);
        measure_freq = DIV_ROUND_UP(32768, 10); /* 10 Hz */
        regmap_write(map, TEMPSENSE1 + REG_SET, measure_freq);
        imx_set_alarm_temp(data, data->temp_passive);
        regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
        regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);

        data->irq_enabled = true;
        data->mode = THERMAL_DEVICE_ENABLED;

        return 0;
}

static int imx_thermal_remove(struct platform_device *pdev)
{
        struct imx_thermal_data *data = platform_get_drvdata(pdev);
        struct regmap *map = data->tempmon;

        /* Disable measurements */
        regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
        if (!IS_ERR(data->thermal_clk))
                clk_disable_unprepare(data->thermal_clk);

        thermal_zone_device_unregister(data->tz);
        cpufreq_cooling_unregister(data->cdev);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int imx_thermal_suspend(struct device *dev)
{
        struct imx_thermal_data *data = dev_get_drvdata(dev);
        struct regmap *map = data->tempmon;

        /*
         * Need to disable thermal sensor, otherwise, when thermal core
         * try to get temperature before thermal sensor resume, a wrong
         * temperature will be read as the thermal sensor is powered
         * down.
         */
        regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
        regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
        data->mode = THERMAL_DEVICE_DISABLED;

        return 0;
}

static int imx_thermal_resume(struct device *dev)
{
        struct imx_thermal_data *data = dev_get_drvdata(dev);
        struct regmap *map = data->tempmon;

        /* Enabled thermal sensor after resume */
        regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
        regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);
        data->mode = THERMAL_DEVICE_ENABLED;

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(imx_thermal_pm_ops,
                         imx_thermal_suspend, imx_thermal_resume);

static const struct of_device_id of_imx_thermal_match[] = {
        { .compatible = "fsl,imx6q-tempmon", },
        { /* end */ }
};
MODULE_DEVICE_TABLE(of, of_imx_thermal_match);

static struct platform_driver imx_thermal = {
        .driver = {
                .name   = "imx_thermal",
                .owner  = THIS_MODULE,
                .pm     = &imx_thermal_pm_ops,
                .of_match_table = of_imx_thermal_match,
        },
        .probe          = imx_thermal_probe,
        .remove         = imx_thermal_remove,
};
module_platform_driver(imx_thermal);

MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("Thermal driver for Freescale i.MX SoCs");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:imx-thermal");