// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright 2020 Google LLC.

#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>
#include <linux/slab.h>

struct cros_ec_regulator_data {
        struct regulator_desc desc;
        struct regulator_dev *dev;
        struct cros_ec_device *ec_dev;

        u32 index;

        u16 *voltages_mV;
        u16 num_voltages;
};

static int cros_ec_cmd(struct cros_ec_device *ec, u32 version, u32 command,
                       void *outdata, u32 outsize, void *indata, u32 insize)
{
        struct cros_ec_command *msg;
        int ret;

        msg = kzalloc(sizeof(*msg) + max(outsize, insize), GFP_KERNEL);
        if (!msg)
                return -ENOMEM;

        msg->version = version;
        msg->command = command;
        msg->outsize = outsize;
        msg->insize = insize;

        if (outdata && outsize > 0)
                memcpy(msg->data, outdata, outsize);

        ret = cros_ec_cmd_xfer_status(ec, msg);
        if (ret < 0)
                goto cleanup;

        if (insize)
                memcpy(indata, msg->data, insize);

cleanup:
        kfree(msg);
        return ret;
}

static int cros_ec_regulator_enable(struct regulator_dev *dev)
{
        struct cros_ec_regulator_data *data = rdev_get_drvdata(dev);
        struct ec_params_regulator_enable cmd = {
                .index = data->index,
                .enable = 1,
        };

        return cros_ec_cmd(data->ec_dev, 0, EC_CMD_REGULATOR_ENABLE, &cmd,
                          sizeof(cmd), NULL, 0);
}

static int cros_ec_regulator_disable(struct regulator_dev *dev)
{
        struct cros_ec_regulator_data *data = rdev_get_drvdata(dev);
        struct ec_params_regulator_enable cmd = {
                .index = data->index,
                .enable = 0,
        };

        return cros_ec_cmd(data->ec_dev, 0, EC_CMD_REGULATOR_ENABLE, &cmd,
                          sizeof(cmd), NULL, 0);
}

static int cros_ec_regulator_is_enabled(struct regulator_dev *dev)
{
        struct cros_ec_regulator_data *data = rdev_get_drvdata(dev);
        struct ec_params_regulator_is_enabled cmd = {
                .index = data->index,
        };
        struct ec_response_regulator_is_enabled resp;
        int ret;

        ret = cros_ec_cmd(data->ec_dev, 0, EC_CMD_REGULATOR_IS_ENABLED, &cmd,
                          sizeof(cmd), &resp, sizeof(resp));
        if (ret < 0)
                return ret;
        return resp.enabled;
}

static int cros_ec_regulator_list_voltage(struct regulator_dev *dev,
                                          unsigned int selector)
{
        struct cros_ec_regulator_data *data = rdev_get_drvdata(dev);

        if (selector >= data->num_voltages)
                return -EINVAL;

        return data->voltages_mV[selector] * 1000;
}

static int cros_ec_regulator_get_voltage(struct regulator_dev *dev)
{
        struct cros_ec_regulator_data *data = rdev_get_drvdata(dev);
        struct ec_params_regulator_get_voltage cmd = {
                .index = data->index,
        };
        struct ec_response_regulator_get_voltage resp;
        int ret;

        ret = cros_ec_cmd(data->ec_dev, 0, EC_CMD_REGULATOR_GET_VOLTAGE, &cmd,
                          sizeof(cmd), &resp, sizeof(resp));
        if (ret < 0)
                return ret;
        return resp.voltage_mv * 1000;
}

static int cros_ec_regulator_set_voltage(struct regulator_dev *dev, int min_uV,
                                         int max_uV, unsigned int *selector)
{
        struct cros_ec_regulator_data *data = rdev_get_drvdata(dev);
        int min_mV = DIV_ROUND_UP(min_uV, 1000);
        int max_mV = max_uV / 1000;
        struct ec_params_regulator_set_voltage cmd = {
                .index = data->index,
                .min_mv = min_mV,
                .max_mv = max_mV,
        };

        /*
         * This can happen when the given range [min_uV, max_uV] doesn't
         * contain any voltage that can be represented exactly in mV.
         */
        if (min_mV > max_mV)
                return -EINVAL;

        return cros_ec_cmd(data->ec_dev, 0, EC_CMD_REGULATOR_SET_VOLTAGE, &cmd,
                           sizeof(cmd), NULL, 0);
}

static const struct regulator_ops cros_ec_regulator_voltage_ops = {
        .enable = cros_ec_regulator_enable,
        .disable = cros_ec_regulator_disable,
        .is_enabled = cros_ec_regulator_is_enabled,
        .list_voltage = cros_ec_regulator_list_voltage,
        .get_voltage = cros_ec_regulator_get_voltage,
        .set_voltage = cros_ec_regulator_set_voltage,
};

static int cros_ec_regulator_init_info(struct device *dev,
                                       struct cros_ec_regulator_data *data)
{
        struct ec_params_regulator_get_info cmd = {
                .index = data->index,
        };
        struct ec_response_regulator_get_info resp;
        int ret;

        ret = cros_ec_cmd(data->ec_dev, 0, EC_CMD_REGULATOR_GET_INFO, &cmd,
                           sizeof(cmd), &resp, sizeof(resp));
        if (ret < 0)
                return ret;

        data->num_voltages =
                min_t(u16, ARRAY_SIZE(resp.voltages_mv), resp.num_voltages);
        data->voltages_mV =
                devm_kmemdup(dev, resp.voltages_mv,
                             sizeof(u16) * data->num_voltages, GFP_KERNEL);
        if (!data->voltages_mV)
                return -ENOMEM;

        data->desc.n_voltages = data->num_voltages;

        /* Make sure the returned name is always a valid string */
        resp.name[ARRAY_SIZE(resp.name) - 1] = '\0';
        data->desc.name = devm_kstrdup(dev, resp.name, GFP_KERNEL);
        if (!data->desc.name)
                return -ENOMEM;

        return 0;
}

static int cros_ec_regulator_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct cros_ec_regulator_data *drvdata;
        struct regulator_init_data *init_data;
        struct regulator_config cfg = {};
        struct regulator_desc *desc;
        int ret;

        drvdata = devm_kzalloc(
                &pdev->dev, sizeof(struct cros_ec_regulator_data), GFP_KERNEL);
        if (!drvdata)
                return -ENOMEM;

        drvdata->ec_dev = dev_get_drvdata(dev->parent);
        desc = &drvdata->desc;

        init_data = of_get_regulator_init_data(dev, np, desc);
        if (!init_data)
                return -EINVAL;

        ret = of_property_read_u32(np, "reg", &drvdata->index);
        if (ret < 0)
                return ret;

        desc->owner = THIS_MODULE;
        desc->type = REGULATOR_VOLTAGE;
        desc->ops = &cros_ec_regulator_voltage_ops;

        ret = cros_ec_regulator_init_info(dev, drvdata);
        if (ret < 0)
                return ret;

        cfg.dev = &pdev->dev;
        cfg.init_data = init_data;
        cfg.driver_data = drvdata;
        cfg.of_node = np;

        drvdata->dev = devm_regulator_register(dev, &drvdata->desc, &cfg);
        if (IS_ERR(drvdata->dev)) {
                ret = PTR_ERR(drvdata->dev);
                dev_err(&pdev->dev, "Failed to register regulator: %d\n", ret);
                return ret;
        }

        platform_set_drvdata(pdev, drvdata);

        return 0;
}

static const struct of_device_id regulator_cros_ec_of_match[] = {
        { .compatible = "google,cros-ec-regulator", },
        {}
};
MODULE_DEVICE_TABLE(of, regulator_cros_ec_of_match);

static struct platform_driver cros_ec_regulator_driver = {
        .probe          = cros_ec_regulator_probe,
        .driver         = {
                .name           = "cros-ec-regulator",
                .of_match_table = regulator_cros_ec_of_match,
        },
};

module_platform_driver(cros_ec_regulator_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChromeOS EC controlled regulator");
MODULE_AUTHOR("Pi-Hsun Shih <pihsun@chromium.org>");