// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for Broadcom BCM2835 SoC temperature sensor
 *
 * Copyright (C) 2016 Martin Sperl
 */

#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/thermal.h>

#include "../thermal_hwmon.h"

#define BCM2835_TS_TSENSCTL                     0x00
#define BCM2835_TS_TSENSSTAT                    0x04

#define BCM2835_TS_TSENSCTL_PRWDW               BIT(0)
#define BCM2835_TS_TSENSCTL_RSTB                BIT(1)

/*
 * bandgap reference voltage in 6 mV increments
 * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
 */
#define BCM2835_TS_TSENSCTL_CTRL_BITS           3
#define BCM2835_TS_TSENSCTL_CTRL_SHIFT          2
#define BCM2835_TS_TSENSCTL_CTRL_MASK               \
        GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS +     \
                BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
                BCM2835_TS_TSENSCTL_CTRL_SHIFT)
#define BCM2835_TS_TSENSCTL_CTRL_DEFAULT        1
#define BCM2835_TS_TSENSCTL_EN_INT              BIT(5)
#define BCM2835_TS_TSENSCTL_DIRECT              BIT(6)
#define BCM2835_TS_TSENSCTL_CLR_INT             BIT(7)
#define BCM2835_TS_TSENSCTL_THOLD_SHIFT         8
#define BCM2835_TS_TSENSCTL_THOLD_BITS          10
#define BCM2835_TS_TSENSCTL_THOLD_MASK               \
        GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
                BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
                BCM2835_TS_TSENSCTL_THOLD_SHIFT)
/*
 * time how long the block to be asserted in reset
 * which based on a clock counter (TSENS clock assumed)
 */
#define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT      18
#define BCM2835_TS_TSENSCTL_RSTDELAY_BITS       8
#define BCM2835_TS_TSENSCTL_REGULEN             BIT(26)

#define BCM2835_TS_TSENSSTAT_DATA_BITS          10
#define BCM2835_TS_TSENSSTAT_DATA_SHIFT         0
#define BCM2835_TS_TSENSSTAT_DATA_MASK               \
        GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS +     \
                BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
                BCM2835_TS_TSENSSTAT_DATA_SHIFT)
#define BCM2835_TS_TSENSSTAT_VALID              BIT(10)
#define BCM2835_TS_TSENSSTAT_INTERRUPT          BIT(11)

struct bcm2835_thermal_data {
        struct thermal_zone_device *tz;
        void __iomem *regs;
        struct clk *clk;
        struct dentry *debugfsdir;
};

static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
{
        return offset + slope * adc;
}

static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
{
        temp -= offset;
        temp /= slope;

        return clamp(temp, 0, (int)BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1);
}

static int bcm2835_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
{
        struct bcm2835_thermal_data *data = thermal_zone_device_priv(tz);
        u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);

        if (!(val & BCM2835_TS_TSENSSTAT_VALID))
                return -EIO;

        val &= BCM2835_TS_TSENSSTAT_DATA_MASK;

        *temp = bcm2835_thermal_adc2temp(
                val,
                thermal_zone_get_offset(data->tz),
                thermal_zone_get_slope(data->tz));

        return 0;
}

static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
        {
                .name = "ctl",
                .offset = 0
        },
        {
                .name = "stat",
                .offset = 4
        }
};

static void bcm2835_thermal_debugfs(struct platform_device *pdev)
{
        struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
        struct debugfs_regset32 *regset;

        data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);

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

        regset->regs = bcm2835_thermal_regs;
        regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
        regset->base = data->regs;

        debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
}

static const struct thermal_zone_device_ops bcm2835_thermal_ops = {
        .get_temp = bcm2835_thermal_get_temp,
};

/*
 * Note: as per Raspberry Foundation FAQ
 * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
 * the recommended temperature range for the SoC -40C to +85C
 * so the trip limit is set to 80C.
 * this applies to all the BCM283X SoC
 */

static const struct of_device_id bcm2835_thermal_of_match_table[] = {
        {
                .compatible = "brcm,bcm2835-thermal",
        },
        {
                .compatible = "brcm,bcm2836-thermal",
        },
        {
                .compatible = "brcm,bcm2837-thermal",
        },
        {},
};
MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);

static int bcm2835_thermal_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        const struct of_device_id *match;
        struct thermal_zone_device *tz;
        struct bcm2835_thermal_data *data;
        int err = 0;
        u32 val;
        unsigned long rate;

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

        match = of_match_device(bcm2835_thermal_of_match_table, dev);
        if (!match)
                return -EINVAL;

        data->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
        if (IS_ERR(data->regs)) {
                err = PTR_ERR(data->regs);
                return err;
        }

        data->clk = devm_clk_get_enabled(dev, NULL);
        if (IS_ERR(data->clk))
                return dev_err_probe(dev, PTR_ERR(data->clk), "Could not get clk\n");

        rate = clk_get_rate(data->clk);
        if ((rate < 1920000) || (rate > 5000000))
                dev_warn(dev,
                         "Clock %pC running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
                         data->clk, rate);

        /* register of thermal sensor and get info from DT */
        tz = devm_thermal_of_zone_register(dev, 0, data, &bcm2835_thermal_ops);
        if (IS_ERR(tz))
                return dev_err_probe(dev, PTR_ERR(tz), "Failed to register the thermal device\n");

        /*
         * right now the FW does set up the HW-block, so we are not
         * touching the configuration registers.
         * But if the HW is not enabled, then set it up
         * using "sane" values used by the firmware right now.
         */
        val = readl(data->regs + BCM2835_TS_TSENSCTL);
        if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
                int offset, slope, crit_temp;

                slope = thermal_zone_get_slope(tz);
                offset = thermal_zone_get_offset(tz);
                /*
                 * For now we deal only with critical, otherwise
                 * would need to iterate
                 */
                err = thermal_zone_get_crit_temp(tz, &crit_temp);
                if (err < 0) {
                        dev_err(dev, "Not able to read trip_temp: %d\n", err);
                        return err;
                }

                /* set bandgap reference voltage and enable voltage regulator */
                val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
                       BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
                      BCM2835_TS_TSENSCTL_REGULEN;

                /* use the recommended reset duration */
                val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);

                /*  trip_adc value from info */
                val |= bcm2835_thermal_temp2adc(crit_temp,
                                                offset,
                                                slope)
                        << BCM2835_TS_TSENSCTL_THOLD_SHIFT;

                /* write the value back to the register as 2 steps */
                writel(val, data->regs + BCM2835_TS_TSENSCTL);
                val |= BCM2835_TS_TSENSCTL_RSTB;
                writel(val, data->regs + BCM2835_TS_TSENSCTL);
        }

        data->tz = tz;

        platform_set_drvdata(pdev, data);

        /*
         * Thermal_zone doesn't enable hwmon as default,
         * enable it here
         */
        err = thermal_add_hwmon_sysfs(tz);
        if (err)
                return err;

        bcm2835_thermal_debugfs(pdev);

        return 0;
}

static void bcm2835_thermal_remove(struct platform_device *pdev)
{
        struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);

        debugfs_remove_recursive(data->debugfsdir);
}

static struct platform_driver bcm2835_thermal_driver = {
        .probe = bcm2835_thermal_probe,
        .remove = bcm2835_thermal_remove,
        .driver = {
                .name = "bcm2835_thermal",
                .of_match_table = bcm2835_thermal_of_match_table,
        },
};
module_platform_driver(bcm2835_thermal_driver);

MODULE_AUTHOR("Martin Sperl");
MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
MODULE_LICENSE("GPL");