// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * IBM OPAL RTC driver
 * Copyright (C) 2014 IBM
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define DRVNAME         "rtc-opal"

#include <linux/module.h>
#include <linux/err.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <asm/opal.h>
#include <asm/firmware.h>

static void opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
{
        tm->tm_year = ((bcd2bin(y_m_d >> 24) * 100) +
                       bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
        tm->tm_mon  = bcd2bin((y_m_d >> 8) & 0xff) - 1;
        tm->tm_mday = bcd2bin(y_m_d & 0xff);
        tm->tm_hour = bcd2bin((h_m_s_ms >> 56) & 0xff);
        tm->tm_min  = bcd2bin((h_m_s_ms >> 48) & 0xff);
        tm->tm_sec  = bcd2bin((h_m_s_ms >> 40) & 0xff);

        tm->tm_wday = -1;
}

static void tm_to_opal(struct rtc_time *tm, u32 *y_m_d, u64 *h_m_s_ms)
{
        *y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) / 100)) << 24;
        *y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) % 100)) << 16;
        *y_m_d |= ((u32)bin2bcd((tm->tm_mon + 1))) << 8;
        *y_m_d |= ((u32)bin2bcd(tm->tm_mday));

        *h_m_s_ms |= ((u64)bin2bcd(tm->tm_hour)) << 56;
        *h_m_s_ms |= ((u64)bin2bcd(tm->tm_min)) << 48;
        *h_m_s_ms |= ((u64)bin2bcd(tm->tm_sec)) << 40;
}

static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm)
{
        s64 rc = OPAL_BUSY;
        int retries = 10;
        u32 y_m_d;
        u64 h_m_s_ms;
        __be32 __y_m_d;
        __be64 __h_m_s_ms;

        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
                if (rc == OPAL_BUSY_EVENT) {
                        msleep(OPAL_BUSY_DELAY_MS);
                        opal_poll_events(NULL);
                } else if (rc == OPAL_BUSY) {
                        msleep(OPAL_BUSY_DELAY_MS);
                } else if (rc == OPAL_HARDWARE || rc == OPAL_INTERNAL_ERROR) {
                        if (retries--) {
                                msleep(10); /* Wait 10ms before retry */
                                rc = OPAL_BUSY; /* go around again */
                        }
                }
        }

        if (rc != OPAL_SUCCESS)
                return -EIO;

        y_m_d = be32_to_cpu(__y_m_d);
        h_m_s_ms = be64_to_cpu(__h_m_s_ms);
        opal_to_tm(y_m_d, h_m_s_ms, tm);

        return 0;
}

static int opal_set_rtc_time(struct device *dev, struct rtc_time *tm)
{
        s64 rc = OPAL_BUSY;
        int retries = 10;
        u32 y_m_d = 0;
        u64 h_m_s_ms = 0;

        tm_to_opal(tm, &y_m_d, &h_m_s_ms);

        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_rtc_write(y_m_d, h_m_s_ms);
                if (rc == OPAL_BUSY_EVENT) {
                        msleep(OPAL_BUSY_DELAY_MS);
                        opal_poll_events(NULL);
                } else if (rc == OPAL_BUSY) {
                        msleep(OPAL_BUSY_DELAY_MS);
                } else if (rc == OPAL_HARDWARE || rc == OPAL_INTERNAL_ERROR) {
                        if (retries--) {
                                msleep(10); /* Wait 10ms before retry */
                                rc = OPAL_BUSY; /* go around again */
                        }
                }
        }

        return rc == OPAL_SUCCESS ? 0 : -EIO;
}

/*
 * TPO  Timed Power-On
 *
 * TPO get/set OPAL calls care about the hour and min and to make it consistent
 * with the rtc utility time conversion functions, we use the 'u64' to store
 * its value and perform bit shift by 32 before use..
 */
static int opal_get_tpo_time(struct device *dev, struct rtc_wkalrm *alarm)
{
        __be32 __y_m_d, __h_m;
        struct opal_msg msg;
        int rc, token;
        u64 h_m_s_ms;
        u32 y_m_d;

        token = opal_async_get_token_interruptible();
        if (token < 0) {
                if (token != -ERESTARTSYS)
                        pr_err("Failed to get the async token\n");

                return token;
        }

        rc = opal_tpo_read(token, &__y_m_d, &__h_m);
        if (rc != OPAL_ASYNC_COMPLETION) {
                rc = -EIO;
                goto exit;
        }

        rc = opal_async_wait_response(token, &msg);
        if (rc) {
                rc = -EIO;
                goto exit;
        }

        rc = opal_get_async_rc(msg);
        if (rc != OPAL_SUCCESS) {
                rc = -EIO;
                goto exit;
        }

        y_m_d = be32_to_cpu(__y_m_d);
        h_m_s_ms = ((u64)be32_to_cpu(__h_m) << 32);

        /* check if no alarm is set */
        if (y_m_d == 0 && h_m_s_ms == 0) {
                pr_debug("No alarm is set\n");
                rc = -ENOENT;
                goto exit;
        } else {
                pr_debug("Alarm set to %x %llx\n", y_m_d, h_m_s_ms);
        }

        opal_to_tm(y_m_d, h_m_s_ms, &alarm->time);

exit:
        opal_async_release_token(token);
        return rc;
}

/* Set Timed Power-On */
static int opal_set_tpo_time(struct device *dev, struct rtc_wkalrm *alarm)
{
        u64 h_m_s_ms = 0;
        struct opal_msg msg;
        u32 y_m_d = 0;
        int token, rc;

        /* if alarm is enabled */
        if (alarm->enabled) {
                tm_to_opal(&alarm->time, &y_m_d, &h_m_s_ms);
                pr_debug("Alarm set to %x %llx\n", y_m_d, h_m_s_ms);

        } else {
                pr_debug("Alarm getting disabled\n");
        }

        token = opal_async_get_token_interruptible();
        if (token < 0) {
                if (token != -ERESTARTSYS)
                        pr_err("Failed to get the async token\n");

                return token;
        }

        /* TPO, we care about hour and minute */
        rc = opal_tpo_write(token, y_m_d,
                            (u32)((h_m_s_ms >> 32) & 0xffff0000));
        if (rc != OPAL_ASYNC_COMPLETION) {
                rc = -EIO;
                goto exit;
        }

        rc = opal_async_wait_response(token, &msg);
        if (rc) {
                rc = -EIO;
                goto exit;
        }

        rc = opal_get_async_rc(msg);
        if (rc != OPAL_SUCCESS)
                rc = -EIO;

exit:
        opal_async_release_token(token);
        return rc;
}

static int opal_tpo_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct rtc_wkalrm alarm = { .enabled = 0 };

        /*
         * TPO is automatically enabled when opal_set_tpo_time() is called with
         * non-zero rtc-time. We only handle disable case which needs to be
         * explicitly told to opal.
         */
        return enabled ? 0 : opal_set_tpo_time(dev, &alarm);
}

static const struct rtc_class_ops opal_rtc_ops = {
        .read_time      = opal_get_rtc_time,
        .set_time       = opal_set_rtc_time,
        .read_alarm     = opal_get_tpo_time,
        .set_alarm      = opal_set_tpo_time,
        .alarm_irq_enable = opal_tpo_alarm_irq_enable,
};

static int opal_rtc_probe(struct platform_device *pdev)
{
        struct rtc_device *rtc;

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

        if (pdev->dev.of_node &&
            (of_property_read_bool(pdev->dev.of_node, "wakeup-source") ||
             of_property_read_bool(pdev->dev.of_node, "has-tpo")/* legacy */))
                device_set_wakeup_capable(&pdev->dev, true);
        else
                clear_bit(RTC_FEATURE_ALARM, rtc->features);

        rtc->ops = &opal_rtc_ops;
        rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
        rtc->range_max = RTC_TIMESTAMP_END_9999;
        clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);

        return devm_rtc_register_device(rtc);
}

static const struct of_device_id opal_rtc_match[] = {
        {
                .compatible     = "ibm,opal-rtc",
        },
        { }
};
MODULE_DEVICE_TABLE(of, opal_rtc_match);

static const struct platform_device_id opal_rtc_driver_ids[] = {
        {
                .name           = "opal-rtc",
        },
        { }
};
MODULE_DEVICE_TABLE(platform, opal_rtc_driver_ids);

static struct platform_driver opal_rtc_driver = {
        .probe          = opal_rtc_probe,
        .id_table       = opal_rtc_driver_ids,
        .driver         = {
                .name           = DRVNAME,
                .of_match_table = opal_rtc_match,
        },
};

static int __init opal_rtc_init(void)
{
        if (!firmware_has_feature(FW_FEATURE_OPAL))
                return -ENODEV;

        return platform_driver_register(&opal_rtc_driver);
}

static void __exit opal_rtc_exit(void)
{
        platform_driver_unregister(&opal_rtc_driver);
}

MODULE_AUTHOR("Neelesh Gupta <neelegup@linux.vnet.ibm.com>");
MODULE_DESCRIPTION("IBM OPAL RTC driver");
MODULE_LICENSE("GPL");

module_init(opal_rtc_init);
module_exit(opal_rtc_exit);