/*
 *  R-Car Gen3 THS thermal sensor driver
 *  Based on rcar_thermal.c and work from Hien Dang and Khiem Nguyen.
 *
 * Copyright (C) 2016 Renesas Electronics Corporation.
 * Copyright (C) 2016 Sang Engineering
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 */
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/spinlock.h>
#include <linux/thermal.h>

#include "thermal_core.h"

/* Register offsets */
#define REG_GEN3_IRQSTR         0x04
#define REG_GEN3_IRQMSK         0x08
#define REG_GEN3_IRQCTL         0x0C
#define REG_GEN3_IRQEN          0x10
#define REG_GEN3_IRQTEMP1       0x14
#define REG_GEN3_IRQTEMP2       0x18
#define REG_GEN3_IRQTEMP3       0x1C
#define REG_GEN3_CTSR           0x20
#define REG_GEN3_THCTR          0x20
#define REG_GEN3_TEMP           0x28
#define REG_GEN3_THCODE1        0x50
#define REG_GEN3_THCODE2        0x54
#define REG_GEN3_THCODE3        0x58

/* IRQ{STR,MSK,EN} bits */
#define IRQ_TEMP1               BIT(0)
#define IRQ_TEMP2               BIT(1)
#define IRQ_TEMP3               BIT(2)
#define IRQ_TEMPD1              BIT(3)
#define IRQ_TEMPD2              BIT(4)
#define IRQ_TEMPD3              BIT(5)

/* CTSR bits */
#define CTSR_PONM       BIT(8)
#define CTSR_AOUT       BIT(7)
#define CTSR_THBGR      BIT(5)
#define CTSR_VMEN       BIT(4)
#define CTSR_VMST       BIT(1)
#define CTSR_THSST      BIT(0)

/* THCTR bits */
#define THCTR_PONM      BIT(6)
#define THCTR_THSST     BIT(0)

#define CTEMP_MASK      0xFFF

#define MCELSIUS(temp)  ((temp) * 1000)
#define GEN3_FUSE_MASK  0xFFF

#define TSC_MAX_NUM     3

/* Structure for thermal temperature calculation */
struct equation_coefs {
        int a1;
        int b1;
        int a2;
        int b2;
};

struct rcar_gen3_thermal_tsc {
        void __iomem *base;
        struct thermal_zone_device *zone;
        struct equation_coefs coef;
        int low;
        int high;
};

struct rcar_gen3_thermal_priv {
        struct rcar_gen3_thermal_tsc *tscs[TSC_MAX_NUM];
        unsigned int num_tscs;
        spinlock_t lock; /* Protect interrupts on and off */
        const struct rcar_gen3_thermal_data *data;
};

struct rcar_gen3_thermal_data {
        void (*thermal_init)(struct rcar_gen3_thermal_tsc *tsc);
};

static inline u32 rcar_gen3_thermal_read(struct rcar_gen3_thermal_tsc *tsc,
                                         u32 reg)
{
        return ioread32(tsc->base + reg);
}

static inline void rcar_gen3_thermal_write(struct rcar_gen3_thermal_tsc *tsc,
                                           u32 reg, u32 data)
{
        iowrite32(data, tsc->base + reg);
}

/*
 * Linear approximation for temperature
 *
 * [reg] = [temp] * a + b => [temp] = ([reg] - b) / a
 *
 * The constants a and b are calculated using two triplets of int values PTAT
 * and THCODE. PTAT and THCODE can either be read from hardware or use hard
 * coded values from driver. The formula to calculate a and b are taken from
 * BSP and sparsely documented and understood.
 *
 * Examining the linear formula and the formula used to calculate constants a
 * and b while knowing that the span for PTAT and THCODE values are between
 * 0x000 and 0xfff the largest integer possible is 0xfff * 0xfff == 0xffe001.
 * Integer also needs to be signed so that leaves 7 bits for binary
 * fixed point scaling.
 */

#define FIXPT_SHIFT 7
#define FIXPT_INT(_x) ((_x) << FIXPT_SHIFT)
#define INT_FIXPT(_x) ((_x) >> FIXPT_SHIFT)
#define FIXPT_DIV(_a, _b) DIV_ROUND_CLOSEST(((_a) << FIXPT_SHIFT), (_b))
#define FIXPT_TO_MCELSIUS(_x) ((_x) * 1000 >> FIXPT_SHIFT)

#define RCAR3_THERMAL_GRAN 500 /* mili Celsius */

/* no idea where these constants come from */
#define TJ_1 96
#define TJ_3 -41

static void rcar_gen3_thermal_calc_coefs(struct equation_coefs *coef,
                                         int *ptat, int *thcode)
{
        int tj_2;

        /* TODO: Find documentation and document constant calculation formula */

        /*
         * Division is not scaled in BSP and if scaled it might overflow
         * the dividend (4095 * 4095 << 14 > INT_MAX) so keep it unscaled
         */
        tj_2 = (FIXPT_INT((ptat[1] - ptat[2]) * 137)
                / (ptat[0] - ptat[2])) - FIXPT_INT(41);

        coef->a1 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[2]),
                             tj_2 - FIXPT_INT(TJ_3));
        coef->b1 = FIXPT_INT(thcode[2]) - coef->a1 * TJ_3;

        coef->a2 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[0]),
                             tj_2 - FIXPT_INT(TJ_1));
        coef->b2 = FIXPT_INT(thcode[0]) - coef->a2 * TJ_1;
}

static int rcar_gen3_thermal_round(int temp)
{
        int result, round_offs;

        round_offs = temp >= 0 ? RCAR3_THERMAL_GRAN / 2 :
                -RCAR3_THERMAL_GRAN / 2;
        result = (temp + round_offs) / RCAR3_THERMAL_GRAN;
        return result * RCAR3_THERMAL_GRAN;
}

static int rcar_gen3_thermal_get_temp(void *devdata, int *temp)
{
        struct rcar_gen3_thermal_tsc *tsc = devdata;
        int mcelsius, val1, val2;
        u32 reg;

        /* Read register and convert to mili Celsius */
        reg = rcar_gen3_thermal_read(tsc, REG_GEN3_TEMP) & CTEMP_MASK;

        val1 = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b1, tsc->coef.a1);
        val2 = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b2, tsc->coef.a2);
        mcelsius = FIXPT_TO_MCELSIUS((val1 + val2) / 2);

        /* Make sure we are inside specifications */
        if ((mcelsius < MCELSIUS(-40)) || (mcelsius > MCELSIUS(125)))
                return -EIO;

        /* Round value to device granularity setting */
        *temp = rcar_gen3_thermal_round(mcelsius);

        return 0;
}

static int rcar_gen3_thermal_mcelsius_to_temp(struct rcar_gen3_thermal_tsc *tsc,
                                              int mcelsius)
{
        int celsius, val1, val2;

        celsius = DIV_ROUND_CLOSEST(mcelsius, 1000);
        val1 = celsius * tsc->coef.a1 + tsc->coef.b1;
        val2 = celsius * tsc->coef.a2 + tsc->coef.b2;

        return INT_FIXPT((val1 + val2) / 2);
}

static int rcar_gen3_thermal_set_trips(void *devdata, int low, int high)
{
        struct rcar_gen3_thermal_tsc *tsc = devdata;

        low = clamp_val(low, -40000, 125000);
        high = clamp_val(high, -40000, 125000);

        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQTEMP1,
                                rcar_gen3_thermal_mcelsius_to_temp(tsc, low));

        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQTEMP2,
                                rcar_gen3_thermal_mcelsius_to_temp(tsc, high));

        tsc->low = low;
        tsc->high = high;

        return 0;
}

static struct thermal_zone_of_device_ops rcar_gen3_tz_of_ops = {
        .get_temp       = rcar_gen3_thermal_get_temp,
        .set_trips      = rcar_gen3_thermal_set_trips,
};

static void rcar_thermal_irq_set(struct rcar_gen3_thermal_priv *priv, bool on)
{
        unsigned int i;
        u32 val = on ? IRQ_TEMPD1 | IRQ_TEMP2 : 0;

        for (i = 0; i < priv->num_tscs; i++)
                rcar_gen3_thermal_write(priv->tscs[i], REG_GEN3_IRQMSK, val);
}

static irqreturn_t rcar_gen3_thermal_irq(int irq, void *data)
{
        struct rcar_gen3_thermal_priv *priv = data;
        u32 status;
        int i, ret = IRQ_HANDLED;

        spin_lock(&priv->lock);
        for (i = 0; i < priv->num_tscs; i++) {
                status = rcar_gen3_thermal_read(priv->tscs[i], REG_GEN3_IRQSTR);
                rcar_gen3_thermal_write(priv->tscs[i], REG_GEN3_IRQSTR, 0);
                if (status)
                        ret = IRQ_WAKE_THREAD;
        }

        if (ret == IRQ_WAKE_THREAD)
                rcar_thermal_irq_set(priv, false);

        spin_unlock(&priv->lock);

        return ret;
}

static irqreturn_t rcar_gen3_thermal_irq_thread(int irq, void *data)
{
        struct rcar_gen3_thermal_priv *priv = data;
        unsigned long flags;
        int i;

        for (i = 0; i < priv->num_tscs; i++)
                thermal_zone_device_update(priv->tscs[i]->zone,
                                           THERMAL_EVENT_UNSPECIFIED);

        spin_lock_irqsave(&priv->lock, flags);
        rcar_thermal_irq_set(priv, true);
        spin_unlock_irqrestore(&priv->lock, flags);

        return IRQ_HANDLED;
}

static void r8a7795_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
{
        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  CTSR_THBGR);
        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  0x0);

        usleep_range(1000, 2000);

        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR, CTSR_PONM);

        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQMSK, 0);
        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQEN, IRQ_TEMPD1 | IRQ_TEMP2);

        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,
                                CTSR_PONM | CTSR_AOUT | CTSR_THBGR | CTSR_VMEN);

        usleep_range(100, 200);

        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,
                                CTSR_PONM | CTSR_AOUT | CTSR_THBGR | CTSR_VMEN |
                                CTSR_VMST | CTSR_THSST);

        usleep_range(1000, 2000);
}

static void r8a7796_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
{
        u32 reg_val;

        reg_val = rcar_gen3_thermal_read(tsc, REG_GEN3_THCTR);
        reg_val &= ~THCTR_PONM;
        rcar_gen3_thermal_write(tsc, REG_GEN3_THCTR, reg_val);

        usleep_range(1000, 2000);

        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQMSK, 0);
        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQEN, IRQ_TEMPD1 | IRQ_TEMP2);

        reg_val = rcar_gen3_thermal_read(tsc, REG_GEN3_THCTR);
        reg_val |= THCTR_THSST;
        rcar_gen3_thermal_write(tsc, REG_GEN3_THCTR, reg_val);

        usleep_range(1000, 2000);
}

static const struct rcar_gen3_thermal_data r8a7795_data = {
        .thermal_init = r8a7795_thermal_init,
};

static const struct rcar_gen3_thermal_data r8a7796_data = {
        .thermal_init = r8a7796_thermal_init,
};

static const struct of_device_id rcar_gen3_thermal_dt_ids[] = {
        { .compatible = "renesas,r8a7795-thermal", .data = &r8a7795_data},
        { .compatible = "renesas,r8a7796-thermal", .data = &r8a7796_data},
        {},
};
MODULE_DEVICE_TABLE(of, rcar_gen3_thermal_dt_ids);

static int rcar_gen3_thermal_remove(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;

        pm_runtime_put(dev);
        pm_runtime_disable(dev);

        return 0;
}

static int rcar_gen3_thermal_probe(struct platform_device *pdev)
{
        struct rcar_gen3_thermal_priv *priv;
        struct device *dev = &pdev->dev;
        struct resource *res;
        struct thermal_zone_device *zone;
        int ret, irq, i;
        char *irqname;

        /* default values if FUSEs are missing */
        /* TODO: Read values from hardware on supported platforms */
        int ptat[3] = { 2351, 1509, 435 };
        int thcode[TSC_MAX_NUM][3] = {
                { 3248, 2800, 2221 },
                { 3245, 2795, 2216 },
                { 3250, 2805, 2237 },
        };

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

        priv->data = of_device_get_match_data(dev);

        spin_lock_init(&priv->lock);

        platform_set_drvdata(pdev, priv);

        /*
         * Request 2 (of the 3 possible) IRQs, the driver only needs to
         * to trigger on the low and high trip points of the current
         * temp window at this point.
         */
        for (i = 0; i < 2; i++) {
                irq = platform_get_irq(pdev, i);
                if (irq < 0)
                        return irq;

                irqname = devm_kasprintf(dev, GFP_KERNEL, "%s:ch%d",
                                         dev_name(dev), i);
                if (!irqname)
                        return -ENOMEM;

                ret = devm_request_threaded_irq(dev, irq, rcar_gen3_thermal_irq,
                                                rcar_gen3_thermal_irq_thread,
                                                IRQF_SHARED, irqname, priv);
                if (ret)
                        return ret;
        }

        pm_runtime_enable(dev);
        pm_runtime_get_sync(dev);

        for (i = 0; i < TSC_MAX_NUM; i++) {
                struct rcar_gen3_thermal_tsc *tsc;

                res = platform_get_resource(pdev, IORESOURCE_MEM, i);
                if (!res)
                        break;

                tsc = devm_kzalloc(dev, sizeof(*tsc), GFP_KERNEL);
                if (!tsc) {
                        ret = -ENOMEM;
                        goto error_unregister;
                }

                tsc->base = devm_ioremap_resource(dev, res);
                if (IS_ERR(tsc->base)) {
                        ret = PTR_ERR(tsc->base);
                        goto error_unregister;
                }

                priv->tscs[i] = tsc;

                priv->data->thermal_init(tsc);
                rcar_gen3_thermal_calc_coefs(&tsc->coef, ptat, thcode[i]);

                zone = devm_thermal_zone_of_sensor_register(dev, i, tsc,
                                                            &rcar_gen3_tz_of_ops);
                if (IS_ERR(zone)) {
                        dev_err(dev, "Can't register thermal zone\n");
                        ret = PTR_ERR(zone);
                        goto error_unregister;
                }
                tsc->zone = zone;

                ret = of_thermal_get_ntrips(tsc->zone);
                if (ret < 0)
                        goto error_unregister;

                dev_info(dev, "TSC%d: Loaded %d trip points\n", i, ret);
        }

        priv->num_tscs = i;

        if (!priv->num_tscs) {
                ret = -ENODEV;
                goto error_unregister;
        }

        rcar_thermal_irq_set(priv, true);

        return 0;

error_unregister:
        rcar_gen3_thermal_remove(pdev);

        return ret;
}

static int __maybe_unused rcar_gen3_thermal_suspend(struct device *dev)
{
        struct rcar_gen3_thermal_priv *priv = dev_get_drvdata(dev);

        rcar_thermal_irq_set(priv, false);

        return 0;
}

static int __maybe_unused rcar_gen3_thermal_resume(struct device *dev)
{
        struct rcar_gen3_thermal_priv *priv = dev_get_drvdata(dev);
        unsigned int i;

        for (i = 0; i < priv->num_tscs; i++) {
                struct rcar_gen3_thermal_tsc *tsc = priv->tscs[i];

                priv->data->thermal_init(tsc);
                rcar_gen3_thermal_set_trips(tsc, tsc->low, tsc->high);
        }

        rcar_thermal_irq_set(priv, true);

        return 0;
}

static SIMPLE_DEV_PM_OPS(rcar_gen3_thermal_pm_ops, rcar_gen3_thermal_suspend,
                         rcar_gen3_thermal_resume);

static struct platform_driver rcar_gen3_thermal_driver = {
        .driver = {
                .name   = "rcar_gen3_thermal",
                .pm = &rcar_gen3_thermal_pm_ops,
                .of_match_table = rcar_gen3_thermal_dt_ids,
        },
        .probe          = rcar_gen3_thermal_probe,
        .remove         = rcar_gen3_thermal_remove,
};
module_platform_driver(rcar_gen3_thermal_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("R-Car Gen3 THS thermal sensor driver");
MODULE_AUTHOR("Wolfram Sang <wsa+renesas@sang-engineering.com>");