/*
 * System Control and Power Interface(SCPI) based hwmon sensor driver
 *
 * Copyright (C) 2015 ARM Ltd.
 * Punit Agrawal <punit.agrawal@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/scpi_protocol.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/thermal.h>

struct sensor_data {
        struct scpi_sensor_info info;
        struct device_attribute dev_attr_input;
        struct device_attribute dev_attr_label;
        char input[20];
        char label[20];
};

struct scpi_thermal_zone {
        int sensor_id;
        struct scpi_sensors *scpi_sensors;
};

struct scpi_sensors {
        struct scpi_ops *scpi_ops;
        struct sensor_data *data;
        struct list_head thermal_zones;
        struct attribute **attrs;
        struct attribute_group group;
        const struct attribute_group *groups[2];
};

static int scpi_read_temp(void *dev, int *temp)
{
        struct scpi_thermal_zone *zone = dev;
        struct scpi_sensors *scpi_sensors = zone->scpi_sensors;
        struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
        struct sensor_data *sensor = &scpi_sensors->data[zone->sensor_id];
        u64 value;
        int ret;

        ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
        if (ret)
                return ret;

        *temp = value;
        return 0;
}

/* hwmon callback functions */
static ssize_t
scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct scpi_sensors *scpi_sensors = dev_get_drvdata(dev);
        struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
        struct sensor_data *sensor;
        u64 value;
        int ret;

        sensor = container_of(attr, struct sensor_data, dev_attr_input);

        ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
        if (ret)
                return ret;

        return sprintf(buf, "%llu\n", value);
}

static ssize_t
scpi_show_label(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct sensor_data *sensor;

        sensor = container_of(attr, struct sensor_data, dev_attr_label);

        return sprintf(buf, "%s\n", sensor->info.name);
}

static struct thermal_zone_of_device_ops scpi_sensor_ops = {
        .get_temp = scpi_read_temp,
};

static int scpi_hwmon_probe(struct platform_device *pdev)
{
        u16 nr_sensors, i;
        int num_temp = 0, num_volt = 0, num_current = 0, num_power = 0;
        int num_energy = 0;
        struct scpi_ops *scpi_ops;
        struct device *hwdev, *dev = &pdev->dev;
        struct scpi_sensors *scpi_sensors;
        int idx, ret;

        scpi_ops = get_scpi_ops();
        if (!scpi_ops)
                return -EPROBE_DEFER;

        ret = scpi_ops->sensor_get_capability(&nr_sensors);
        if (ret)
                return ret;

        if (!nr_sensors)
                return -ENODEV;

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

        scpi_sensors->data = devm_kcalloc(dev, nr_sensors,
                                   sizeof(*scpi_sensors->data), GFP_KERNEL);
        if (!scpi_sensors->data)
                return -ENOMEM;

        scpi_sensors->attrs = devm_kcalloc(dev, (nr_sensors * 2) + 1,
                                   sizeof(*scpi_sensors->attrs), GFP_KERNEL);
        if (!scpi_sensors->attrs)
                return -ENOMEM;

        scpi_sensors->scpi_ops = scpi_ops;

        for (i = 0, idx = 0; i < nr_sensors; i++) {
                struct sensor_data *sensor = &scpi_sensors->data[idx];

                ret = scpi_ops->sensor_get_info(i, &sensor->info);
                if (ret)
                        return ret;

                switch (sensor->info.class) {
                case TEMPERATURE:
                        snprintf(sensor->input, sizeof(sensor->input),
                                 "temp%d_input", num_temp + 1);
                        snprintf(sensor->label, sizeof(sensor->input),
                                 "temp%d_label", num_temp + 1);
                        num_temp++;
                        break;
                case VOLTAGE:
                        snprintf(sensor->input, sizeof(sensor->input),
                                 "in%d_input", num_volt);
                        snprintf(sensor->label, sizeof(sensor->input),
                                 "in%d_label", num_volt);
                        num_volt++;
                        break;
                case CURRENT:
                        snprintf(sensor->input, sizeof(sensor->input),
                                 "curr%d_input", num_current + 1);
                        snprintf(sensor->label, sizeof(sensor->input),
                                 "curr%d_label", num_current + 1);
                        num_current++;
                        break;
                case POWER:
                        snprintf(sensor->input, sizeof(sensor->input),
                                 "power%d_input", num_power + 1);
                        snprintf(sensor->label, sizeof(sensor->input),
                                 "power%d_label", num_power + 1);
                        num_power++;
                        break;
                case ENERGY:
                        snprintf(sensor->input, sizeof(sensor->input),
                                 "energy%d_input", num_energy + 1);
                        snprintf(sensor->label, sizeof(sensor->input),
                                 "energy%d_label", num_energy + 1);
                        num_energy++;
                        break;
                default:
                        continue;
                }

                sensor->dev_attr_input.attr.mode = S_IRUGO;
                sensor->dev_attr_input.show = scpi_show_sensor;
                sensor->dev_attr_input.attr.name = sensor->input;

                sensor->dev_attr_label.attr.mode = S_IRUGO;
                sensor->dev_attr_label.show = scpi_show_label;
                sensor->dev_attr_label.attr.name = sensor->label;

                scpi_sensors->attrs[idx << 1] = &sensor->dev_attr_input.attr;
                scpi_sensors->attrs[(idx << 1) + 1] = &sensor->dev_attr_label.attr;

                sysfs_attr_init(scpi_sensors->attrs[idx << 1]);
                sysfs_attr_init(scpi_sensors->attrs[(idx << 1) + 1]);
                idx++;
        }

        scpi_sensors->group.attrs = scpi_sensors->attrs;
        scpi_sensors->groups[0] = &scpi_sensors->group;

        platform_set_drvdata(pdev, scpi_sensors);

        hwdev = devm_hwmon_device_register_with_groups(dev,
                        "scpi_sensors", scpi_sensors, scpi_sensors->groups);

        if (IS_ERR(hwdev))
                return PTR_ERR(hwdev);

        /*
         * Register the temperature sensors with the thermal framework
         * to allow their usage in setting up the thermal zones from
         * device tree.
         *
         * NOTE: Not all temperature sensors maybe used for thermal
         * control
         */
        INIT_LIST_HEAD(&scpi_sensors->thermal_zones);
        for (i = 0; i < nr_sensors; i++) {
                struct sensor_data *sensor = &scpi_sensors->data[i];
                struct thermal_zone_device *z;
                struct scpi_thermal_zone *zone;

                if (sensor->info.class != TEMPERATURE)
                        continue;

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

                zone->sensor_id = i;
                zone->scpi_sensors = scpi_sensors;
                z = devm_thermal_zone_of_sensor_register(dev,
                                                         sensor->info.sensor_id,
                                                         zone,
                                                         &scpi_sensor_ops);
                /*
                 * The call to thermal_zone_of_sensor_register returns
                 * an error for sensors that are not associated with
                 * any thermal zones or if the thermal subsystem is
                 * not configured.
                 */
                if (IS_ERR(z)) {
                        devm_kfree(dev, zone);
                        continue;
                }
        }

        return 0;
}

static const struct of_device_id scpi_of_match[] = {
        {.compatible = "arm,scpi-sensors"},
        {},
};
MODULE_DEVICE_TABLE(of, scpi_of_match);

static struct platform_driver scpi_hwmon_platdrv = {
        .driver = {
                .name   = "scpi-hwmon",
                .of_match_table = scpi_of_match,
        },
        .probe          = scpi_hwmon_probe,
};
module_platform_driver(scpi_hwmon_platdrv);

MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
MODULE_LICENSE("GPL v2");