// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */

#include <linux/bits.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>

#define OFS_FAN_INST    0 /* Is 0 because plreg base will be set at INST */
#define OFS_FAN_FAIL    2 /* Is 2 bytes after base */
#define OFS_SEVSTAT     0 /* Is 0 because fn2 base will be set at SEVSTAT */
#define POWER_BIT       24

struct gxp_fan_ctrl_drvdata {
        void __iomem    *base;
        void __iomem    *plreg;
        void __iomem    *fn2;
};

static bool fan_installed(struct device *dev, int fan)
{
        struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
        u8 val;

        val = readb(drvdata->plreg + OFS_FAN_INST);

        return !!(val & BIT(fan));
}

static long fan_failed(struct device *dev, int fan)
{
        struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
        u8 val;

        val = readb(drvdata->plreg + OFS_FAN_FAIL);

        return !!(val & BIT(fan));
}

static long fan_enabled(struct device *dev, int fan)
{
        struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
        u32 val;

        /*
         * Check the power status as if the platform is off the value
         * reported for the PWM will be incorrect. Report fan as
         * disabled.
         */
        val = readl(drvdata->fn2 + OFS_SEVSTAT);

        return !!((val & BIT(POWER_BIT)) && fan_installed(dev, fan));
}

static int gxp_pwm_write(struct device *dev, u32 attr, int channel, long val)
{
        struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);

        switch (attr) {
        case hwmon_pwm_input:
                if (val > 255 || val < 0)
                        return -EINVAL;
                writeb(val, drvdata->base + channel);
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static int gxp_fan_ctrl_write(struct device *dev, enum hwmon_sensor_types type,
                              u32 attr, int channel, long val)
{
        switch (type) {
        case hwmon_pwm:
                return gxp_pwm_write(dev, attr, channel, val);
        default:
                return -EOPNOTSUPP;
        }
}

static int gxp_fan_read(struct device *dev, u32 attr, int channel, long *val)
{
        switch (attr) {
        case hwmon_fan_enable:
                *val = fan_enabled(dev, channel);
                return 0;
        case hwmon_fan_fault:
                *val = fan_failed(dev, channel);
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static int gxp_pwm_read(struct device *dev, u32 attr, int channel, long *val)
{
        struct gxp_fan_ctrl_drvdata *drvdata = dev_get_drvdata(dev);
        u32 reg;

        /*
         * Check the power status of the platform. If the platform is off
         * the value reported for the PWM will be incorrect. In this case
         * report a PWM of zero.
         */

        reg = readl(drvdata->fn2 + OFS_SEVSTAT);

        if (reg & BIT(POWER_BIT))
                *val = fan_installed(dev, channel) ? readb(drvdata->base + channel) : 0;
        else
                *val = 0;

        return 0;
}

static int gxp_fan_ctrl_read(struct device *dev, enum hwmon_sensor_types type,
                             u32 attr, int channel, long *val)
{
        switch (type) {
        case hwmon_fan:
                return gxp_fan_read(dev, attr, channel, val);
        case hwmon_pwm:
                return gxp_pwm_read(dev, attr, channel, val);
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t gxp_fan_ctrl_is_visible(const void *_data,
                                       enum hwmon_sensor_types type,
                                       u32 attr, int channel)
{
        umode_t mode = 0;

        switch (type) {
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_enable:
                case hwmon_fan_fault:
                        mode = 0444;
                        break;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        mode = 0644;
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return mode;
}

static const struct hwmon_ops gxp_fan_ctrl_ops = {
        .is_visible = gxp_fan_ctrl_is_visible,
        .read = gxp_fan_ctrl_read,
        .write = gxp_fan_ctrl_write,
};

static const struct hwmon_channel_info * const gxp_fan_ctrl_info[] = {
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_FAULT | HWMON_F_ENABLE),
        HWMON_CHANNEL_INFO(pwm,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT),
        NULL
};

static const struct hwmon_chip_info gxp_fan_ctrl_chip_info = {
        .ops = &gxp_fan_ctrl_ops,
        .info = gxp_fan_ctrl_info,

};

static int gxp_fan_ctrl_probe(struct platform_device *pdev)
{
        struct gxp_fan_ctrl_drvdata *drvdata;
        struct device *dev = &pdev->dev;
        struct device *hwmon_dev;

        drvdata = devm_kzalloc(dev, sizeof(struct gxp_fan_ctrl_drvdata),
                               GFP_KERNEL);
        if (!drvdata)
                return -ENOMEM;

        drvdata->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
        if (IS_ERR(drvdata->base))
                return dev_err_probe(dev, PTR_ERR(drvdata->base),
                                     "failed to map base\n");

        drvdata->plreg = devm_platform_ioremap_resource_byname(pdev,
                                                               "pl");
        if (IS_ERR(drvdata->plreg))
                return dev_err_probe(dev, PTR_ERR(drvdata->plreg),
                                     "failed to map plreg\n");

        drvdata->fn2 = devm_platform_ioremap_resource_byname(pdev,
                                                             "fn2");
        if (IS_ERR(drvdata->fn2))
                return dev_err_probe(dev, PTR_ERR(drvdata->fn2),
                                     "failed to map fn2\n");

        hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
                                                         "hpe_gxp_fan_ctrl",
                                                         drvdata,
                                                         &gxp_fan_ctrl_chip_info,
                                                         NULL);

        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct of_device_id gxp_fan_ctrl_of_match[] = {
        { .compatible = "hpe,gxp-fan-ctrl", },
        {},
};
MODULE_DEVICE_TABLE(of, gxp_fan_ctrl_of_match);

static struct platform_driver gxp_fan_ctrl_driver = {
        .probe          = gxp_fan_ctrl_probe,
        .driver = {
                .name   = "gxp-fan-ctrl",
                .of_match_table = gxp_fan_ctrl_of_match,
        },
};
module_platform_driver(gxp_fan_ctrl_driver);

MODULE_AUTHOR("Nick Hawkins <nick.hawkins@hpe.com>");
MODULE_DESCRIPTION("HPE GXP fan controller");
MODULE_LICENSE("GPL");