// SPDX-License-Identifier: GPL-2.0
// RTC driver for ChromeOS Embedded Controller.
//
// Copyright (C) 2017 Google, Inc.
// Author: Stephen Barber <smbarber@chromium.org>

#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>

#define DRV_NAME        "cros-ec-rtc"

#define SECS_PER_DAY    (24 * 60 * 60)

/**
 * struct cros_ec_rtc - Driver data for EC RTC
 *
 * @cros_ec: Pointer to EC device
 * @rtc: Pointer to RTC device
 * @notifier: Notifier info for responding to EC events
 * @saved_alarm: Alarm to restore when interrupts are reenabled
 */
struct cros_ec_rtc {
        struct cros_ec_device *cros_ec;
        struct rtc_device *rtc;
        struct notifier_block notifier;
        u32 saved_alarm;
};

static int cros_ec_rtc_get(struct cros_ec_device *cros_ec, u32 command,
                           u32 *response)
{
        DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
                        sizeof(struct ec_response_rtc));
        int ret;

        msg->command = command;
        msg->insize = sizeof(struct ec_response_rtc);

        ret = cros_ec_cmd_xfer_status(cros_ec, msg);
        if (ret < 0)
                return ret;

        *response = ((struct ec_response_rtc *)msg->data)->time;

        return 0;
}

static int cros_ec_rtc_set(struct cros_ec_device *cros_ec, u32 command,
                           u32 param)
{
        DEFINE_RAW_FLEX(struct cros_ec_command, msg, data,
                        sizeof(struct ec_response_rtc));
        int ret;

        msg->command = command;
        msg->outsize = sizeof(struct ec_response_rtc);
        ((struct ec_response_rtc *)msg->data)->time = param;

        ret = cros_ec_cmd_xfer_status(cros_ec, msg);
        if (ret < 0)
                return ret;
        return 0;
}

/* Read the current time from the EC. */
static int cros_ec_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
        struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
        int ret;
        u32 time;

        ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &time);
        if (ret) {
                dev_err(dev, "error getting time: %d\n", ret);
                return ret;
        }

        rtc_time64_to_tm(time, tm);

        return 0;
}

/* Set the current EC time. */
static int cros_ec_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
        struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
        int ret;
        time64_t time = rtc_tm_to_time64(tm);

        ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_VALUE, (u32)time);
        if (ret < 0) {
                dev_err(dev, "error setting time: %d\n", ret);
                return ret;
        }

        return 0;
}

/* Read alarm time from RTC. */
static int cros_ec_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
        struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
        int ret;
        u32 current_time, alarm_offset;

        /*
         * The EC host command for getting the alarm is relative (i.e. 5
         * seconds from now) whereas rtc_wkalrm is absolute. Get the current
         * RTC time first so we can calculate the relative time.
         */
        ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
        if (ret < 0) {
                dev_err(dev, "error getting time: %d\n", ret);
                return ret;
        }

        ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM, &alarm_offset);
        if (ret < 0) {
                dev_err(dev, "error getting alarm: %d\n", ret);
                return ret;
        }

        rtc_time64_to_tm(current_time + alarm_offset, &alrm->time);

        return 0;
}

/* Set the EC's RTC alarm. */
static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
        struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
        int ret;
        time64_t alarm_time;
        u32 current_time, alarm_offset;

        /*
         * The EC host command for setting the alarm is relative
         * (i.e. 5 seconds from now) whereas rtc_wkalrm is absolute.
         * Get the current RTC time first so we can calculate the
         * relative time.
         */
        ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
        if (ret < 0) {
                dev_err(dev, "error getting time: %d\n", ret);
                return ret;
        }

        alarm_time = rtc_tm_to_time64(&alrm->time);

        if (alarm_time < 0 || alarm_time > U32_MAX)
                return -EINVAL;

        if (!alrm->enabled) {
                /*
                 * If the alarm is being disabled, send an alarm
                 * clear command.
                 */
                alarm_offset = EC_RTC_ALARM_CLEAR;
                cros_ec_rtc->saved_alarm = (u32)alarm_time;
        } else {
                /* Don't set an alarm in the past. */
                if ((u32)alarm_time <= current_time)
                        return -ETIME;

                alarm_offset = (u32)alarm_time - current_time;
        }

        ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
        if (ret < 0) {
                dev_err(dev, "error setting alarm in %u seconds: %d\n",
                        alarm_offset, ret);
                /*
                 * The EC code returns -EINVAL if the alarm time is too
                 * far in the future. Convert it to the expected error code.
                 */
                if (ret == -EINVAL)
                        ret = -ERANGE;
                return ret;
        }

        return 0;
}

static int cros_ec_rtc_alarm_irq_enable(struct device *dev,
                                        unsigned int enabled)
{
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(dev);
        struct cros_ec_device *cros_ec = cros_ec_rtc->cros_ec;
        int ret;
        u32 current_time, alarm_offset, alarm_value;

        ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_VALUE, &current_time);
        if (ret < 0) {
                dev_err(dev, "error getting time: %d\n", ret);
                return ret;
        }

        if (enabled) {
                /* Restore saved alarm if it's still in the future. */
                if (cros_ec_rtc->saved_alarm < current_time)
                        alarm_offset = EC_RTC_ALARM_CLEAR;
                else
                        alarm_offset = cros_ec_rtc->saved_alarm - current_time;

                ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
                                      alarm_offset);
                if (ret < 0) {
                        dev_err(dev, "error restoring alarm: %d\n", ret);
                        return ret;
                }
        } else {
                /* Disable alarm, saving the old alarm value. */
                ret = cros_ec_rtc_get(cros_ec, EC_CMD_RTC_GET_ALARM,
                                      &alarm_offset);
                if (ret < 0) {
                        dev_err(dev, "error saving alarm: %d\n", ret);
                        return ret;
                }

                alarm_value = current_time + alarm_offset;

                /*
                 * If the current EC alarm is already past, we don't want
                 * to set an alarm when we go through the alarm irq enable
                 * path.
                 */
                if (alarm_value < current_time)
                        cros_ec_rtc->saved_alarm = EC_RTC_ALARM_CLEAR;
                else
                        cros_ec_rtc->saved_alarm = alarm_value;

                alarm_offset = EC_RTC_ALARM_CLEAR;
                ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
                                      alarm_offset);
                if (ret < 0) {
                        dev_err(dev, "error disabling alarm: %d\n", ret);
                        return ret;
                }
        }

        return 0;
}

static int cros_ec_rtc_event(struct notifier_block *nb,
                             unsigned long queued_during_suspend,
                             void *_notify)
{
        struct cros_ec_rtc *cros_ec_rtc;
        struct rtc_device *rtc;
        struct cros_ec_device *cros_ec;
        u32 host_event;

        cros_ec_rtc = container_of(nb, struct cros_ec_rtc, notifier);
        rtc = cros_ec_rtc->rtc;
        cros_ec = cros_ec_rtc->cros_ec;

        host_event = cros_ec_get_host_event(cros_ec);
        if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_RTC)) {
                rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
                return NOTIFY_OK;
        } else {
                return NOTIFY_DONE;
        }
}

static const struct rtc_class_ops cros_ec_rtc_ops = {
        .read_time = cros_ec_rtc_read_time,
        .set_time = cros_ec_rtc_set_time,
        .read_alarm = cros_ec_rtc_read_alarm,
        .set_alarm = cros_ec_rtc_set_alarm,
        .alarm_irq_enable = cros_ec_rtc_alarm_irq_enable,
};

#ifdef CONFIG_PM_SLEEP
static int cros_ec_rtc_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);

        if (device_may_wakeup(dev))
                return enable_irq_wake(cros_ec_rtc->cros_ec->irq);

        return 0;
}

static int cros_ec_rtc_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct cros_ec_rtc *cros_ec_rtc = dev_get_drvdata(&pdev->dev);

        if (device_may_wakeup(dev))
                return disable_irq_wake(cros_ec_rtc->cros_ec->irq);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(cros_ec_rtc_pm_ops, cros_ec_rtc_suspend,
                         cros_ec_rtc_resume);

static int cros_ec_rtc_probe(struct platform_device *pdev)
{
        struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
        struct cros_ec_device *cros_ec = ec_dev->ec_dev;
        struct cros_ec_rtc *cros_ec_rtc;
        struct rtc_time tm;
        int ret;

        cros_ec_rtc = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_rtc),
                                   GFP_KERNEL);
        if (!cros_ec_rtc)
                return -ENOMEM;

        platform_set_drvdata(pdev, cros_ec_rtc);
        cros_ec_rtc->cros_ec = cros_ec;

        /* Get initial time */
        ret = cros_ec_rtc_read_time(&pdev->dev, &tm);
        if (ret) {
                dev_err(&pdev->dev, "failed to read RTC time\n");
                return ret;
        }

        ret = device_init_wakeup(&pdev->dev, true);
        if (ret) {
                dev_err(&pdev->dev, "failed to initialize wakeup\n");
                return ret;
        }

        cros_ec_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(cros_ec_rtc->rtc))
                return PTR_ERR(cros_ec_rtc->rtc);

        cros_ec_rtc->rtc->ops = &cros_ec_rtc_ops;
        cros_ec_rtc->rtc->range_max = U32_MAX;

        /*
         * The RTC on some older Chromebooks can only handle alarms less than
         * 24 hours in the future. The only way to find out is to try to set an
         * alarm further in the future. If that fails, assume that the RTC
         * connected to the EC can only handle less than 24 hours of alarm
         * window.
         */
        ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, SECS_PER_DAY * 2);
        if (ret == -EINVAL)
                cros_ec_rtc->rtc->alarm_offset_max = SECS_PER_DAY - 1;

        (void)cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM,
                              EC_RTC_ALARM_CLEAR);

        ret = devm_rtc_register_device(cros_ec_rtc->rtc);
        if (ret)
                return ret;

        /* Get RTC events from the EC. */
        cros_ec_rtc->notifier.notifier_call = cros_ec_rtc_event;
        ret = blocking_notifier_chain_register(&cros_ec->event_notifier,
                                               &cros_ec_rtc->notifier);
        if (ret) {
                dev_err(&pdev->dev, "failed to register notifier\n");
                return ret;
        }

        return 0;
}

static void cros_ec_rtc_remove(struct platform_device *pdev)
{
        struct cros_ec_rtc *cros_ec_rtc = platform_get_drvdata(pdev);
        struct device *dev = &pdev->dev;
        int ret;

        ret = blocking_notifier_chain_unregister(
                                &cros_ec_rtc->cros_ec->event_notifier,
                                &cros_ec_rtc->notifier);
        if (ret)
                dev_err(dev, "failed to unregister notifier\n");
}

static const struct platform_device_id cros_ec_rtc_id[] = {
        { DRV_NAME, 0 },
        {}
};
MODULE_DEVICE_TABLE(platform, cros_ec_rtc_id);

static struct platform_driver cros_ec_rtc_driver = {
        .probe = cros_ec_rtc_probe,
        .remove = cros_ec_rtc_remove,
        .driver = {
                .name = DRV_NAME,
                .pm = &cros_ec_rtc_pm_ops,
        },
        .id_table = cros_ec_rtc_id,
};

module_platform_driver(cros_ec_rtc_driver);

MODULE_DESCRIPTION("RTC driver for Chrome OS ECs");
MODULE_AUTHOR("Stephen Barber <smbarber@chromium.org>");
MODULE_LICENSE("GPL v2");