root/drivers/rtc/rtc-rx8010.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the Epson RTC module RX-8010 SJ
 *
 * Copyright(C) Timesys Corporation 2015
 * Copyright(C) General Electric Company 2015
 */

#include <linux/bcd.h>
#include <linux/bitops.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/rtc.h>

#define RX8010_SEC              0x10
#define RX8010_MIN              0x11
#define RX8010_HOUR             0x12
#define RX8010_WDAY             0x13
#define RX8010_MDAY             0x14
#define RX8010_MONTH            0x15
#define RX8010_YEAR             0x16
#define RX8010_RESV17           0x17
#define RX8010_ALMIN            0x18
#define RX8010_ALHOUR           0x19
#define RX8010_ALWDAY           0x1A
#define RX8010_TCOUNT0          0x1B
#define RX8010_TCOUNT1          0x1C
#define RX8010_EXT              0x1D
#define RX8010_FLAG             0x1E
#define RX8010_CTRL             0x1F
/* 0x20 to 0x2F are user registers */
#define RX8010_RESV30           0x30
#define RX8010_RESV31           0x31
#define RX8010_IRQ              0x32

#define RX8010_EXT_WADA         BIT(3)

#define RX8010_FLAG_VLF         BIT(1)
#define RX8010_FLAG_AF          BIT(3)
#define RX8010_FLAG_TF          BIT(4)
#define RX8010_FLAG_UF          BIT(5)

#define RX8010_CTRL_AIE         BIT(3)
#define RX8010_CTRL_UIE         BIT(5)
#define RX8010_CTRL_STOP        BIT(6)
#define RX8010_CTRL_TEST        BIT(7)

#define RX8010_ALARM_AE         BIT(7)

static const struct i2c_device_id rx8010_id[] = {
        { "rx8010" },
        { }
};
MODULE_DEVICE_TABLE(i2c, rx8010_id);

static const __maybe_unused struct of_device_id rx8010_of_match[] = {
        { .compatible = "epson,rx8010" },
        { }
};
MODULE_DEVICE_TABLE(of, rx8010_of_match);

struct rx8010_data {
        struct regmap *regs;
        struct rtc_device *rtc;
        u8 ctrlreg;
};

static irqreturn_t rx8010_irq_1_handler(int irq, void *dev_id)
{
        struct i2c_client *client = dev_id;
        struct rx8010_data *rx8010 = i2c_get_clientdata(client);
        int flagreg, err;

        rtc_lock(rx8010->rtc);

        err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
        if (err) {
                rtc_unlock(rx8010->rtc);
                return IRQ_NONE;
        }

        if (flagreg & RX8010_FLAG_VLF)
                dev_warn(&client->dev, "Frequency stop detected\n");

        if (flagreg & RX8010_FLAG_TF) {
                flagreg &= ~RX8010_FLAG_TF;
                rtc_update_irq(rx8010->rtc, 1, RTC_PF | RTC_IRQF);
        }

        if (flagreg & RX8010_FLAG_AF) {
                flagreg &= ~RX8010_FLAG_AF;
                rtc_update_irq(rx8010->rtc, 1, RTC_AF | RTC_IRQF);
        }

        if (flagreg & RX8010_FLAG_UF) {
                flagreg &= ~RX8010_FLAG_UF;
                rtc_update_irq(rx8010->rtc, 1, RTC_UF | RTC_IRQF);
        }

        err = regmap_write(rx8010->regs, RX8010_FLAG, flagreg);
        rtc_unlock(rx8010->rtc);
        return err ? IRQ_NONE : IRQ_HANDLED;
}

static int rx8010_get_time(struct device *dev, struct rtc_time *dt)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        u8 date[RX8010_YEAR - RX8010_SEC + 1];
        int flagreg, err;

        err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
        if (err)
                return err;

        if (flagreg & RX8010_FLAG_VLF) {
                dev_warn(dev, "Frequency stop detected\n");
                return -EINVAL;
        }

        err = regmap_bulk_read(rx8010->regs, RX8010_SEC, date, sizeof(date));
        if (err)
                return err;

        dt->tm_sec = bcd2bin(date[RX8010_SEC - RX8010_SEC] & 0x7f);
        dt->tm_min = bcd2bin(date[RX8010_MIN - RX8010_SEC] & 0x7f);
        dt->tm_hour = bcd2bin(date[RX8010_HOUR - RX8010_SEC] & 0x3f);
        dt->tm_mday = bcd2bin(date[RX8010_MDAY - RX8010_SEC] & 0x3f);
        dt->tm_mon = bcd2bin(date[RX8010_MONTH - RX8010_SEC] & 0x1f) - 1;
        dt->tm_year = bcd2bin(date[RX8010_YEAR - RX8010_SEC]) + 100;
        dt->tm_wday = ffs(date[RX8010_WDAY - RX8010_SEC] & 0x7f);

        return 0;
}

static int rx8010_set_time(struct device *dev, struct rtc_time *dt)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        u8 date[RX8010_YEAR - RX8010_SEC + 1];
        int err;

        /* set STOP bit before changing clock/calendar */
        err = regmap_set_bits(rx8010->regs, RX8010_CTRL, RX8010_CTRL_STOP);
        if (err)
                return err;

        date[RX8010_SEC - RX8010_SEC] = bin2bcd(dt->tm_sec);
        date[RX8010_MIN - RX8010_SEC] = bin2bcd(dt->tm_min);
        date[RX8010_HOUR - RX8010_SEC] = bin2bcd(dt->tm_hour);
        date[RX8010_MDAY - RX8010_SEC] = bin2bcd(dt->tm_mday);
        date[RX8010_MONTH - RX8010_SEC] = bin2bcd(dt->tm_mon + 1);
        date[RX8010_YEAR - RX8010_SEC] = bin2bcd(dt->tm_year - 100);
        date[RX8010_WDAY - RX8010_SEC] = bin2bcd(1 << dt->tm_wday);

        err = regmap_bulk_write(rx8010->regs, RX8010_SEC, date, sizeof(date));
        if (err)
                return err;

        /* clear STOP bit after changing clock/calendar */
        err = regmap_clear_bits(rx8010->regs, RX8010_CTRL, RX8010_CTRL_STOP);
        if (err)
                return err;

        err = regmap_clear_bits(rx8010->regs, RX8010_FLAG, RX8010_FLAG_VLF);
        if (err)
                return err;

        return 0;
}

static int rx8010_init(struct device *dev)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        u8 ctrl[2];
        int need_clear = 0, err;

        /* Initialize reserved registers as specified in datasheet */
        err = regmap_write(rx8010->regs, RX8010_RESV17, 0xD8);
        if (err)
                return err;

        err = regmap_write(rx8010->regs, RX8010_RESV30, 0x00);
        if (err)
                return err;

        err = regmap_write(rx8010->regs, RX8010_RESV31, 0x08);
        if (err)
                return err;

        err = regmap_write(rx8010->regs, RX8010_IRQ, 0x00);
        if (err)
                return err;

        err = regmap_bulk_read(rx8010->regs, RX8010_FLAG, ctrl, 2);
        if (err)
                return err;

        if (ctrl[0] & RX8010_FLAG_VLF)
                dev_warn(dev, "Frequency stop was detected\n");

        if (ctrl[0] & RX8010_FLAG_AF) {
                dev_warn(dev, "Alarm was detected\n");
                need_clear = 1;
        }

        if (ctrl[0] & RX8010_FLAG_TF)
                need_clear = 1;

        if (ctrl[0] & RX8010_FLAG_UF)
                need_clear = 1;

        if (need_clear) {
                ctrl[0] &= ~(RX8010_FLAG_AF | RX8010_FLAG_TF | RX8010_FLAG_UF);
                err = regmap_write(rx8010->regs, RX8010_FLAG, ctrl[0]);
                if (err)
                        return err;
        }

        rx8010->ctrlreg = (ctrl[1] & ~RX8010_CTRL_TEST);

        return 0;
}

static int rx8010_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        u8 alarmvals[3];
        int flagreg, err;

        err = regmap_bulk_read(rx8010->regs, RX8010_ALMIN, alarmvals, 3);
        if (err)
                return err;

        err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
        if (err)
                return err;

        t->time.tm_sec = 0;
        t->time.tm_min = bcd2bin(alarmvals[0] & 0x7f);
        t->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);

        if (!(alarmvals[2] & RX8010_ALARM_AE))
                t->time.tm_mday = bcd2bin(alarmvals[2] & 0x7f);

        t->enabled = !!(rx8010->ctrlreg & RX8010_CTRL_AIE);
        t->pending = (flagreg & RX8010_FLAG_AF) && t->enabled;

        return 0;
}

static int rx8010_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        u8 alarmvals[3];
        int err;

        if (rx8010->ctrlreg & (RX8010_CTRL_AIE | RX8010_CTRL_UIE)) {
                rx8010->ctrlreg &= ~(RX8010_CTRL_AIE | RX8010_CTRL_UIE);
                err = regmap_write(rx8010->regs, RX8010_CTRL, rx8010->ctrlreg);
                if (err)
                        return err;
        }

        err = regmap_clear_bits(rx8010->regs, RX8010_FLAG, RX8010_FLAG_AF);
        if (err)
                return err;

        alarmvals[0] = bin2bcd(t->time.tm_min);
        alarmvals[1] = bin2bcd(t->time.tm_hour);
        alarmvals[2] = bin2bcd(t->time.tm_mday);

        err = regmap_bulk_write(rx8010->regs, RX8010_ALMIN, alarmvals, 2);
        if (err)
                return err;

        err = regmap_clear_bits(rx8010->regs, RX8010_EXT, RX8010_EXT_WADA);
        if (err)
                return err;

        if (alarmvals[2] == 0)
                alarmvals[2] |= RX8010_ALARM_AE;

        err = regmap_write(rx8010->regs, RX8010_ALWDAY, alarmvals[2]);
        if (err)
                return err;

        if (t->enabled) {
                if (rx8010->rtc->uie_rtctimer.enabled)
                        rx8010->ctrlreg |= RX8010_CTRL_UIE;
                if (rx8010->rtc->aie_timer.enabled)
                        rx8010->ctrlreg |=
                                (RX8010_CTRL_AIE | RX8010_CTRL_UIE);

                err = regmap_write(rx8010->regs, RX8010_CTRL, rx8010->ctrlreg);
                if (err)
                        return err;
        }

        return 0;
}

static int rx8010_alarm_irq_enable(struct device *dev,
                                   unsigned int enabled)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        int err;
        u8 ctrl;

        ctrl = rx8010->ctrlreg;

        if (enabled) {
                if (rx8010->rtc->uie_rtctimer.enabled)
                        ctrl |= RX8010_CTRL_UIE;
                if (rx8010->rtc->aie_timer.enabled)
                        ctrl |= (RX8010_CTRL_AIE | RX8010_CTRL_UIE);
        } else {
                if (!rx8010->rtc->uie_rtctimer.enabled)
                        ctrl &= ~RX8010_CTRL_UIE;
                if (!rx8010->rtc->aie_timer.enabled)
                        ctrl &= ~RX8010_CTRL_AIE;
        }

        err = regmap_clear_bits(rx8010->regs, RX8010_FLAG, RX8010_FLAG_AF);
        if (err)
                return err;

        if (ctrl != rx8010->ctrlreg) {
                rx8010->ctrlreg = ctrl;
                err = regmap_write(rx8010->regs, RX8010_CTRL, rx8010->ctrlreg);
                if (err)
                        return err;
        }

        return 0;
}

static int rx8010_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
        struct rx8010_data *rx8010 = dev_get_drvdata(dev);
        int tmp, flagreg, err;

        switch (cmd) {
        case RTC_VL_READ:
                err = regmap_read(rx8010->regs, RX8010_FLAG, &flagreg);
                if (err)
                        return err;

                tmp = flagreg & RX8010_FLAG_VLF ? RTC_VL_DATA_INVALID : 0;
                return put_user(tmp, (unsigned int __user *)arg);

        default:
                return -ENOIOCTLCMD;
        }
}

static const struct rtc_class_ops rx8010_rtc_ops = {
        .read_time = rx8010_get_time,
        .set_time = rx8010_set_time,
        .ioctl = rx8010_ioctl,
        .read_alarm = rx8010_read_alarm,
        .set_alarm = rx8010_set_alarm,
        .alarm_irq_enable = rx8010_alarm_irq_enable,
};

static const struct regmap_config rx8010_regmap_config = {
        .name = "rx8010-rtc",
        .reg_bits = 8,
        .val_bits = 8,
};

static int rx8010_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct rx8010_data *rx8010;
        int err = 0;

        rx8010 = devm_kzalloc(dev, sizeof(*rx8010), GFP_KERNEL);
        if (!rx8010)
                return -ENOMEM;

        i2c_set_clientdata(client, rx8010);

        rx8010->regs = devm_regmap_init_i2c(client, &rx8010_regmap_config);
        if (IS_ERR(rx8010->regs))
                return PTR_ERR(rx8010->regs);

        err = rx8010_init(dev);
        if (err)
                return err;

        rx8010->rtc = devm_rtc_allocate_device(dev);
        if (IS_ERR(rx8010->rtc))
                return PTR_ERR(rx8010->rtc);

        if (client->irq > 0) {
                unsigned long irqflags = IRQF_TRIGGER_LOW;

                if (dev_fwnode(&client->dev))
                        irqflags = 0;

                err = devm_request_threaded_irq(dev, client->irq, NULL,
                                                rx8010_irq_1_handler,
                                                irqflags | IRQF_ONESHOT,
                                                "rx8010", client);
                if (err) {
                        dev_err(dev, "unable to request IRQ\n");
                        return err;
                }
        } else {
                clear_bit(RTC_FEATURE_ALARM, rx8010->rtc->features);
        }

        rx8010->rtc->ops = &rx8010_rtc_ops;
        rx8010->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        rx8010->rtc->range_max = RTC_TIMESTAMP_END_2099;

        return devm_rtc_register_device(rx8010->rtc);
}

static struct i2c_driver rx8010_driver = {
        .driver = {
                .name = "rtc-rx8010",
                .of_match_table = of_match_ptr(rx8010_of_match),
        },
        .probe          = rx8010_probe,
        .id_table       = rx8010_id,
};

module_i2c_driver(rx8010_driver);

MODULE_AUTHOR("Akshay Bhat <akshay.bhat@timesys.com>");
MODULE_DESCRIPTION("Epson RX8010SJ RTC driver");
MODULE_LICENSE("GPL v2");