// SPDX-License-Identifier: GPL-2.0-or-later
/* Lantiq cpu temperature sensor driver
 *
 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>

#include <lantiq_soc.h>

/* gphy1 configuration register contains cpu temperature */
#define CGU_GPHY1_CR   0x0040
#define CGU_TEMP_PD    BIT(19)

static void ltq_cputemp_enable(void)
{
        ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
}

static void ltq_cputemp_disable(void *data)
{
        ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
}

static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
                    u32 attr, int channel, long *temp)
{
        int value;

        switch (attr) {
        case hwmon_temp_input:
                /* get the temperature including one decimal place */
                value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
                value = value * 5;
                /* range -38 to +154 °C, register value zero is -38.0 °C */
                value -= 380;
                /* scale temp to millidegree */
                value = value * 100;
                break;
        default:
                return -EOPNOTSUPP;
        }

        *temp = value;
        return 0;
}

static umode_t ltq_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 ltq_info[] = {
        HWMON_CHANNEL_INFO(chip,
                           HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT),
        NULL
};

static const struct hwmon_ops ltq_hwmon_ops = {
        .is_visible = ltq_is_visible,
        .read = ltq_read,
};

static const struct hwmon_chip_info ltq_chip_info = {
        .ops = &ltq_hwmon_ops,
        .info = ltq_info,
};

static int ltq_cputemp_probe(struct platform_device *pdev)
{
        struct device *hwmon_dev;
        int err = 0;

        /* available on vr9 v1.2 SoCs only */
        if (ltq_soc_type() != SOC_TYPE_VR9_2)
                return -ENODEV;

        err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
        if (err)
                return err;

        ltq_cputemp_enable();

        hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
                                                         "ltq_cputemp",
                                                         NULL,
                                                         &ltq_chip_info,
                                                         NULL);

        if (IS_ERR(hwmon_dev)) {
                dev_err(&pdev->dev, "Failed to register as hwmon device");
                return PTR_ERR(hwmon_dev);
        }

        return 0;
}

const struct of_device_id ltq_cputemp_match[] = {
        { .compatible = "lantiq,cputemp" },
        {},
};
MODULE_DEVICE_TABLE(of, ltq_cputemp_match);

static struct platform_driver ltq_cputemp_driver = {
        .probe = ltq_cputemp_probe,
        .driver = {
                .name = "ltq-cputemp",
                .of_match_table = ltq_cputemp_match,
        },
};

module_platform_driver(ltq_cputemp_driver);

MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
MODULE_LICENSE("GPL");