root/drivers/rtc/rtc-da9052.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Real time clock driver for DA9052
 *
 * Copyright(c) 2012 Dialog Semiconductor Ltd.
 *
 * Author: Dajun Dajun Chen <dajun.chen@diasemi.com>
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/err.h>
#include <linux/delay.h>

#include <linux/mfd/da9052/da9052.h>
#include <linux/mfd/da9052/reg.h>

#define rtc_err(rtc, fmt, ...) \
                dev_err(rtc->da9052->dev, "%s: " fmt, __func__, ##__VA_ARGS__)

#define DA9052_GET_TIME_RETRIES 5

struct da9052_rtc {
        struct rtc_device *rtc;
        struct da9052 *da9052;
};

static int da9052_rtc_enable_alarm(struct da9052_rtc *rtc, bool enable)
{
        int ret;
        if (enable) {
                ret = da9052_reg_update(rtc->da9052, DA9052_ALARM_Y_REG,
                                DA9052_ALARM_Y_ALARM_ON|DA9052_ALARM_Y_TICK_ON,
                                DA9052_ALARM_Y_ALARM_ON);
                if (ret != 0)
                        rtc_err(rtc, "Failed to enable ALM: %d\n", ret);
        } else {
                ret = da9052_reg_update(rtc->da9052, DA9052_ALARM_Y_REG,
                        DA9052_ALARM_Y_ALARM_ON|DA9052_ALARM_Y_TICK_ON, 0);
                if (ret != 0)
                        rtc_err(rtc, "Write error: %d\n", ret);
        }
        return ret;
}

static irqreturn_t da9052_rtc_irq(int irq, void *data)
{
        struct da9052_rtc *rtc = data;

        rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);

        return IRQ_HANDLED;
}

static int da9052_read_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
{
        int ret;
        uint8_t v[2][5];
        int idx = 1;
        int timeout = DA9052_GET_TIME_RETRIES;

        ret = da9052_group_read(rtc->da9052, DA9052_ALARM_MI_REG, 5, &v[0][0]);
        if (ret) {
                rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
                return ret;
        }

        do {
                ret = da9052_group_read(rtc->da9052,
                                        DA9052_ALARM_MI_REG, 5, &v[idx][0]);
                if (ret) {
                        rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
                        return ret;
                }

                if (memcmp(&v[0][0], &v[1][0], 5) == 0) {
                        rtc_tm->tm_year = (v[0][4] & DA9052_RTC_YEAR) + 100;
                        rtc_tm->tm_mon  = (v[0][3] & DA9052_RTC_MONTH) - 1;
                        rtc_tm->tm_mday = v[0][2] & DA9052_RTC_DAY;
                        rtc_tm->tm_hour = v[0][1] & DA9052_RTC_HOUR;
                        rtc_tm->tm_min  = v[0][0] & DA9052_RTC_MIN;
                        rtc_tm->tm_sec = 0;

                        ret = rtc_valid_tm(rtc_tm);
                        return ret;
                }

                idx = (1-idx);
                msleep(20);

        } while (timeout--);

        rtc_err(rtc, "Timed out reading alarm time\n");

        return -EIO;
}

static int da9052_set_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
{
        struct da9052 *da9052 = rtc->da9052;
        unsigned long alm_time;
        int ret;
        uint8_t v[3];

        alm_time = rtc_tm_to_time64(rtc_tm);

        if (rtc_tm->tm_sec > 0) {
                alm_time += 60 - rtc_tm->tm_sec;
                rtc_time64_to_tm(alm_time, rtc_tm);
        }
        BUG_ON(rtc_tm->tm_sec); /* it will cause repeated irqs if not zero */

        rtc_tm->tm_year -= 100;
        rtc_tm->tm_mon += 1;

        ret = da9052_reg_update(da9052, DA9052_ALARM_MI_REG,
                                DA9052_RTC_MIN, rtc_tm->tm_min);
        if (ret != 0) {
                rtc_err(rtc, "Failed to write ALRM MIN: %d\n", ret);
                return ret;
        }

        v[0] = rtc_tm->tm_hour;
        v[1] = rtc_tm->tm_mday;
        v[2] = rtc_tm->tm_mon;

        ret = da9052_group_write(da9052, DA9052_ALARM_H_REG, 3, v);
        if (ret < 0)
                return ret;

        ret = da9052_reg_update(da9052, DA9052_ALARM_Y_REG,
                                DA9052_RTC_YEAR, rtc_tm->tm_year);
        if (ret != 0)
                rtc_err(rtc, "Failed to write ALRM YEAR: %d\n", ret);

        return ret;
}

static int da9052_rtc_get_alarm_status(struct da9052_rtc *rtc)
{
        int ret;

        ret = da9052_reg_read(rtc->da9052, DA9052_ALARM_Y_REG);
        if (ret < 0) {
                rtc_err(rtc, "Failed to read ALM: %d\n", ret);
                return ret;
        }

        return !!(ret&DA9052_ALARM_Y_ALARM_ON);
}

static int da9052_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
{
        struct da9052_rtc *rtc = dev_get_drvdata(dev);
        int ret;
        uint8_t v[2][6];
        int idx = 1;
        int timeout = DA9052_GET_TIME_RETRIES;

        ret = da9052_group_read(rtc->da9052, DA9052_COUNT_S_REG, 6, &v[0][0]);
        if (ret) {
                rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
                return ret;
        }

        do {
                ret = da9052_group_read(rtc->da9052,
                                        DA9052_COUNT_S_REG, 6, &v[idx][0]);
                if (ret) {
                        rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
                        return ret;
                }

                if (memcmp(&v[0][0], &v[1][0], 6) == 0) {
                        rtc_tm->tm_year = (v[0][5] & DA9052_RTC_YEAR) + 100;
                        rtc_tm->tm_mon  = (v[0][4] & DA9052_RTC_MONTH) - 1;
                        rtc_tm->tm_mday = v[0][3] & DA9052_RTC_DAY;
                        rtc_tm->tm_hour = v[0][2] & DA9052_RTC_HOUR;
                        rtc_tm->tm_min  = v[0][1] & DA9052_RTC_MIN;
                        rtc_tm->tm_sec  = v[0][0] & DA9052_RTC_SEC;

                        return 0;
                }

                idx = (1-idx);
                msleep(20);

        } while (timeout--);

        rtc_err(rtc, "Timed out reading time\n");

        return -EIO;
}

static int da9052_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct da9052_rtc *rtc;
        uint8_t v[6];
        int ret;

        /* DA9052 only has 6 bits for year - to represent 2000-2063 */
        if ((tm->tm_year < 100) || (tm->tm_year > 163))
                return -EINVAL;

        rtc = dev_get_drvdata(dev);

        v[0] = tm->tm_sec;
        v[1] = tm->tm_min;
        v[2] = tm->tm_hour;
        v[3] = tm->tm_mday;
        v[4] = tm->tm_mon + 1;
        v[5] = tm->tm_year - 100;

        ret = da9052_group_write(rtc->da9052, DA9052_COUNT_S_REG, 6, v);
        if (ret < 0)
                rtc_err(rtc, "failed to set RTC time: %d\n", ret);
        return ret;
}

static int da9052_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        int ret;
        struct rtc_time *tm = &alrm->time;
        struct da9052_rtc *rtc = dev_get_drvdata(dev);

        ret = da9052_read_alarm(rtc, tm);
        if (ret < 0) {
                rtc_err(rtc, "failed to read RTC alarm: %d\n", ret);
                return ret;
        }

        alrm->enabled = da9052_rtc_get_alarm_status(rtc);
        return 0;
}

static int da9052_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        int ret;
        struct rtc_time *tm = &alrm->time;
        struct da9052_rtc *rtc = dev_get_drvdata(dev);

        /* DA9052 only has 6 bits for year - to represent 2000-2063 */
        if ((tm->tm_year < 100) || (tm->tm_year > 163))
                return -EINVAL;

        ret = da9052_rtc_enable_alarm(rtc, 0);
        if (ret < 0)
                return ret;

        ret = da9052_set_alarm(rtc, tm);
        if (ret < 0)
                return ret;

        ret = da9052_rtc_enable_alarm(rtc, 1);
        return ret;
}

static int da9052_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct da9052_rtc *rtc = dev_get_drvdata(dev);

        return da9052_rtc_enable_alarm(rtc, enabled);
}

static const struct rtc_class_ops da9052_rtc_ops = {
        .read_time      = da9052_rtc_read_time,
        .set_time       = da9052_rtc_set_time,
        .read_alarm     = da9052_rtc_read_alarm,
        .set_alarm      = da9052_rtc_set_alarm,
        .alarm_irq_enable = da9052_rtc_alarm_irq_enable,
};

static int da9052_rtc_probe(struct platform_device *pdev)
{
        struct da9052_rtc *rtc;
        int ret;

        rtc = devm_kzalloc(&pdev->dev, sizeof(struct da9052_rtc), GFP_KERNEL);
        if (!rtc)
                return -ENOMEM;

        rtc->da9052 = dev_get_drvdata(pdev->dev.parent);
        platform_set_drvdata(pdev, rtc);

        ret = da9052_reg_write(rtc->da9052, DA9052_BBAT_CONT_REG, 0xFE);
        if (ret < 0) {
                rtc_err(rtc,
                        "Failed to setup RTC battery charging: %d\n", ret);
                return ret;
        }

        ret = da9052_reg_update(rtc->da9052, DA9052_ALARM_Y_REG,
                                DA9052_ALARM_Y_TICK_ON, 0);
        if (ret != 0)
                rtc_err(rtc, "Failed to disable TICKS: %d\n", ret);

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

        rtc->rtc->ops = &da9052_rtc_ops;
        rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        rtc->rtc->range_max = RTC_TIMESTAMP_END_2063;

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

        ret = da9052_request_irq(rtc->da9052, DA9052_IRQ_ALARM, "ALM",
                                da9052_rtc_irq, rtc);
        if (ret != 0) {
                rtc_err(rtc, "irq registration failed: %d\n", ret);
                return ret;
        }

        return 0;
}

static struct platform_driver da9052_rtc_driver = {
        .probe  = da9052_rtc_probe,
        .driver = {
                .name   = "da9052-rtc",
        },
};

module_platform_driver(da9052_rtc_driver);

MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
MODULE_DESCRIPTION("RTC driver for Dialog DA9052 PMIC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:da9052-rtc");