// SPDX-License-Identifier: GPL-2.0-only
/*
 * HID Sensor Time Driver
 * Copyright (c) 2012, Alexander Holler.
 */
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/hid-sensor-hub.h>
#include <linux/iio/iio.h>
#include <linux/rtc.h>

enum hid_time_channel {
        CHANNEL_SCAN_INDEX_YEAR,
        CHANNEL_SCAN_INDEX_MONTH,
        CHANNEL_SCAN_INDEX_DAY,
        CHANNEL_SCAN_INDEX_HOUR,
        CHANNEL_SCAN_INDEX_MINUTE,
        CHANNEL_SCAN_INDEX_SECOND,
        TIME_RTC_CHANNEL_MAX,
};

struct hid_time_state {
        struct hid_sensor_hub_callbacks callbacks;
        struct hid_sensor_common common_attributes;
        struct hid_sensor_hub_attribute_info info[TIME_RTC_CHANNEL_MAX];
        struct rtc_time last_time;
        spinlock_t lock_last_time;
        struct completion comp_last_time;
        struct rtc_time time_buf;
        struct rtc_device *rtc;
};

static const u32 hid_time_addresses[TIME_RTC_CHANNEL_MAX] = {
        HID_USAGE_SENSOR_TIME_YEAR,
        HID_USAGE_SENSOR_TIME_MONTH,
        HID_USAGE_SENSOR_TIME_DAY,
        HID_USAGE_SENSOR_TIME_HOUR,
        HID_USAGE_SENSOR_TIME_MINUTE,
        HID_USAGE_SENSOR_TIME_SECOND,
};

/* Channel names for verbose error messages */
static const char * const hid_time_channel_names[TIME_RTC_CHANNEL_MAX] = {
        "year", "month", "day", "hour", "minute", "second",
};

/* Callback handler to send event after all samples are received and captured */
static int hid_time_proc_event(struct hid_sensor_hub_device *hsdev,
                                unsigned usage_id, void *priv)
{
        unsigned long flags;
        struct hid_time_state *time_state = platform_get_drvdata(priv);

        spin_lock_irqsave(&time_state->lock_last_time, flags);
        time_state->last_time = time_state->time_buf;
        spin_unlock_irqrestore(&time_state->lock_last_time, flags);
        complete(&time_state->comp_last_time);
        return 0;
}

static u32 hid_time_value(size_t raw_len, char *raw_data)
{
        switch (raw_len) {
        case 1:
                return *(u8 *)raw_data;
        case 2:
                return *(u16 *)raw_data;
        case 4:
                return *(u32 *)raw_data;
        default:
                return (u32)(~0U); /* 0xff... or -1 to denote an error */
        }
}

static int hid_time_capture_sample(struct hid_sensor_hub_device *hsdev,
                                unsigned usage_id, size_t raw_len,
                                char *raw_data, void *priv)
{
        struct hid_time_state *time_state = platform_get_drvdata(priv);
        struct rtc_time *time_buf = &time_state->time_buf;

        switch (usage_id) {
        case HID_USAGE_SENSOR_TIME_YEAR:
                /*
                 * The draft for HID-sensors (HUTRR39) currently doesn't define
                 * the range for the year attribute. Therefor we support
                 * 8 bit (0-99) and 16 or 32 bits (full) as size for the year.
                 */
                if (raw_len == 1) {
                        time_buf->tm_year = *(u8 *)raw_data;
                        if (time_buf->tm_year < 70)
                                /* assume we are in 1970...2069 */
                                time_buf->tm_year += 100;
                } else
                        time_buf->tm_year =
                                (int)hid_time_value(raw_len, raw_data)-1900;
                break;
        case HID_USAGE_SENSOR_TIME_MONTH:
                /* sensors are sending the month as 1-12, we need 0-11 */
                time_buf->tm_mon = (int)hid_time_value(raw_len, raw_data)-1;
                break;
        case HID_USAGE_SENSOR_TIME_DAY:
                time_buf->tm_mday = (int)hid_time_value(raw_len, raw_data);
                break;
        case HID_USAGE_SENSOR_TIME_HOUR:
                time_buf->tm_hour = (int)hid_time_value(raw_len, raw_data);
                break;
        case HID_USAGE_SENSOR_TIME_MINUTE:
                time_buf->tm_min = (int)hid_time_value(raw_len, raw_data);
                break;
        case HID_USAGE_SENSOR_TIME_SECOND:
                time_buf->tm_sec = (int)hid_time_value(raw_len, raw_data);
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

/* small helper, haven't found any other way */
static const char *hid_time_attrib_name(u32 attrib_id)
{
        static const char unknown[] = "unknown";
        unsigned i;

        for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) {
                if (hid_time_addresses[i] == attrib_id)
                        return hid_time_channel_names[i];
        }
        return unknown; /* should never happen */
}

static int hid_time_parse_report(struct platform_device *pdev,
                                struct hid_sensor_hub_device *hsdev,
                                unsigned usage_id,
                                struct hid_time_state *time_state)
{
        int report_id, i;

        for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i)
                if (sensor_hub_input_get_attribute_info(hsdev,
                                HID_INPUT_REPORT, usage_id,
                                hid_time_addresses[i],
                                &time_state->info[i]) < 0)
                        return -EINVAL;
        /* Check the (needed) attributes for sanity */
        report_id = time_state->info[0].report_id;
        if (report_id < 0) {
                dev_err(&pdev->dev, "bad report ID!\n");
                return -EINVAL;
        }
        for (i = 0; i < TIME_RTC_CHANNEL_MAX; ++i) {
                if (time_state->info[i].report_id != report_id) {
                        dev_err(&pdev->dev,
                                "not all needed attributes inside the same report!\n");
                        return -EINVAL;
                }
                if (time_state->info[i].size == 3 ||
                                time_state->info[i].size > 4) {
                        dev_err(&pdev->dev,
                                "attribute '%s' not 8, 16 or 32 bits wide!\n",
                                hid_time_attrib_name(
                                        time_state->info[i].attrib_id));
                        return -EINVAL;
                }
                if (time_state->info[i].units !=
                                HID_USAGE_SENSOR_UNITS_NOT_SPECIFIED &&
                                /* allow attribute seconds with unit seconds */
                                !(time_state->info[i].attrib_id ==
                                HID_USAGE_SENSOR_TIME_SECOND &&
                                time_state->info[i].units ==
                                HID_USAGE_SENSOR_UNITS_SECOND)) {
                        dev_err(&pdev->dev,
                                "attribute '%s' hasn't a unit of type 'none'!\n",
                                hid_time_attrib_name(
                                        time_state->info[i].attrib_id));
                        return -EINVAL;
                }
                if (time_state->info[i].unit_expo) {
                        dev_err(&pdev->dev,
                                "attribute '%s' hasn't a unit exponent of 1!\n",
                                hid_time_attrib_name(
                                        time_state->info[i].attrib_id));
                        return -EINVAL;
                }
        }

        return 0;
}

static int hid_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        unsigned long flags;
        struct hid_time_state *time_state = dev_get_drvdata(dev);
        int ret;

        reinit_completion(&time_state->comp_last_time);
        /* get a report with all values through requesting one value */
        sensor_hub_input_attr_get_raw_value(time_state->common_attributes.hsdev,
                        HID_USAGE_SENSOR_TIME, hid_time_addresses[0],
                        time_state->info[0].report_id, SENSOR_HUB_SYNC, false);
        /* wait for all values (event) */
        ret = wait_for_completion_killable_timeout(
                        &time_state->comp_last_time, HZ*6);
        if (ret > 0) {
                /* no error */
                spin_lock_irqsave(&time_state->lock_last_time, flags);
                *tm = time_state->last_time;
                spin_unlock_irqrestore(&time_state->lock_last_time, flags);
                return 0;
        }
        if (!ret)
                return -EIO; /* timeouted */
        return ret; /* killed (-ERESTARTSYS) */
}

static const struct rtc_class_ops hid_time_rtc_ops = {
        .read_time = hid_rtc_read_time,
};

static int hid_time_probe(struct platform_device *pdev)
{
        int ret = 0;
        struct hid_sensor_hub_device *hsdev = dev_get_platdata(&pdev->dev);
        struct hid_time_state *time_state = devm_kzalloc(&pdev->dev,
                sizeof(struct hid_time_state), GFP_KERNEL);

        if (time_state == NULL)
                return -ENOMEM;

        platform_set_drvdata(pdev, time_state);

        spin_lock_init(&time_state->lock_last_time);
        init_completion(&time_state->comp_last_time);
        time_state->common_attributes.hsdev = hsdev;
        time_state->common_attributes.pdev = pdev;

        ret = hid_sensor_parse_common_attributes(hsdev,
                                HID_USAGE_SENSOR_TIME,
                                &time_state->common_attributes,
                                NULL,
                                0);
        if (ret) {
                dev_err(&pdev->dev, "failed to setup common attributes!\n");
                return ret;
        }

        ret = hid_time_parse_report(pdev, hsdev, HID_USAGE_SENSOR_TIME,
                                        time_state);
        if (ret) {
                dev_err(&pdev->dev, "failed to setup attributes!\n");
                return ret;
        }

        time_state->callbacks.send_event = hid_time_proc_event;
        time_state->callbacks.capture_sample = hid_time_capture_sample;
        time_state->callbacks.pdev = pdev;
        ret = sensor_hub_register_callback(hsdev, HID_USAGE_SENSOR_TIME,
                                        &time_state->callbacks);
        if (ret < 0) {
                dev_err(&pdev->dev, "register callback failed!\n");
                return ret;
        }

        ret = sensor_hub_device_open(hsdev);
        if (ret) {
                dev_err(&pdev->dev, "failed to open sensor hub device!\n");
                goto err_open;
        }

        /*
         * Enable HID input processing early in order to be able to read the
         * clock already in devm_rtc_device_register().
         */
        hid_device_io_start(hsdev->hdev);

        time_state->rtc = devm_rtc_device_register(&pdev->dev,
                                        "hid-sensor-time", &hid_time_rtc_ops,
                                        THIS_MODULE);

        if (IS_ERR(time_state->rtc)) {
                hid_device_io_stop(hsdev->hdev);
                ret = PTR_ERR(time_state->rtc);
                time_state->rtc = NULL;
                dev_err(&pdev->dev, "rtc device register failed!\n");
                goto err_rtc;
        }

        return ret;

err_rtc:
        sensor_hub_device_close(hsdev);
err_open:
        sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TIME);
        return ret;
}

static void hid_time_remove(struct platform_device *pdev)
{
        struct hid_sensor_hub_device *hsdev = dev_get_platdata(&pdev->dev);

        sensor_hub_device_close(hsdev);
        sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TIME);
}

static const struct platform_device_id hid_time_ids[] = {
        {
                /* Format: HID-SENSOR-usage_id_in_hex_lowercase */
                .name = "HID-SENSOR-2000a0",
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, hid_time_ids);

static struct platform_driver hid_time_platform_driver = {
        .id_table = hid_time_ids,
        .driver = {
                .name   = KBUILD_MODNAME,
        },
        .probe          = hid_time_probe,
        .remove         = hid_time_remove,
};
module_platform_driver(hid_time_platform_driver);

MODULE_DESCRIPTION("HID Sensor Time");
MODULE_AUTHOR("Alexander Holler <holler@ahsoftware.de>");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("IIO_HID");