// SPDX-License-Identifier: GPL-2.0-or-later
/* Sparx5 SoC temperature sensor driver
 *
 * Copyright (C) 2020 Lars Povlsen <lars.povlsen@microchip.com>
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/hwmon.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>

#define TEMP_CTRL               0
#define TEMP_CFG                4
#define  TEMP_CFG_CYCLES        GENMASK(24, 15)
#define  TEMP_CFG_ENA           BIT(0)
#define TEMP_STAT               8
#define  TEMP_STAT_VALID        BIT(12)
#define  TEMP_STAT_TEMP         GENMASK(11, 0)

struct s5_hwmon {
        void __iomem *base;
        struct clk *clk;
};

static void s5_temp_enable(struct s5_hwmon *hwmon)
{
        u32 val = readl(hwmon->base + TEMP_CFG);
        u32 clk = clk_get_rate(hwmon->clk) / USEC_PER_SEC;

        val &= ~TEMP_CFG_CYCLES;
        val |= FIELD_PREP(TEMP_CFG_CYCLES, clk);
        val |= TEMP_CFG_ENA;

        writel(val, hwmon->base + TEMP_CFG);
}

static int s5_read(struct device *dev, enum hwmon_sensor_types type,
                   u32 attr, int channel, long *temp)
{
        struct s5_hwmon *hwmon = dev_get_drvdata(dev);
        int rc = 0, value;
        u32 stat;

        switch (attr) {
        case hwmon_temp_input:
                stat = readl_relaxed(hwmon->base + TEMP_STAT);
                if (!(stat & TEMP_STAT_VALID))
                        return -EAGAIN;
                value = stat & TEMP_STAT_TEMP;
                /*
                 * From register documentation:
                 * Temp(C) = TEMP_SENSOR_STAT.TEMP / 4096 * 352.2 - 109.4
                 */
                value = DIV_ROUND_CLOSEST(value * 3522, 4096) - 1094;
                /*
                 * Scale down by 10 from above and multiply by 1000 to
                 * have millidegrees as specified by the hwmon sysfs
                 * interface.
                 */
                value *= 100;
                *temp = value;
                break;
        default:
                rc = -EOPNOTSUPP;
                break;
        }

        return rc;
}

static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
                             u32 attr, int channel)
{
        if (type != hwmon_temp)
                return 0;

        switch (attr) {
        case hwmon_temp_input:
                return 0444;
        default:
                return 0;
        }
}

static const struct hwmon_channel_info * const s5_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
        NULL
};

static const struct hwmon_ops s5_hwmon_ops = {
        .is_visible = s5_is_visible,
        .read = s5_read,
};

static const struct hwmon_chip_info s5_chip_info = {
        .ops = &s5_hwmon_ops,
        .info = s5_info,
};

static int s5_temp_probe(struct platform_device *pdev)
{
        struct device *hwmon_dev;
        struct s5_hwmon *hwmon;

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

        hwmon->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(hwmon->base))
                return PTR_ERR(hwmon->base);

        hwmon->clk = devm_clk_get_enabled(&pdev->dev, NULL);
        if (IS_ERR(hwmon->clk))
                return PTR_ERR(hwmon->clk);

        s5_temp_enable(hwmon);

        hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
                                                         "s5_temp",
                                                         hwmon,
                                                         &s5_chip_info,
                                                         NULL);

        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct of_device_id s5_temp_match[] = {
        { .compatible = "microchip,sparx5-temp" },
        {},
};
MODULE_DEVICE_TABLE(of, s5_temp_match);

static struct platform_driver s5_temp_driver = {
        .probe = s5_temp_probe,
        .driver = {
                .name = "sparx5-temp",
                .of_match_table = s5_temp_match,
        },
};

module_platform_driver(s5_temp_driver);

MODULE_AUTHOR("Lars Povlsen <lars.povlsen@microchip.com>");
MODULE_DESCRIPTION("Sparx5 SoC temperature sensor driver");
MODULE_LICENSE("GPL");