// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) ST-Ericsson SA 2010
 *
 * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
 *
 * RTC clock driver for the RTC part of the AB8500 Power management chip.
 * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
 * Linus Walleij <linus.walleij@stericsson.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/mfd/abx500.h>
#include <linux/mfd/abx500/ab8500.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/pm_wakeirq.h>

#define AB8500_RTC_SOFF_STAT_REG        0x00
#define AB8500_RTC_CC_CONF_REG          0x01
#define AB8500_RTC_READ_REQ_REG         0x02
#define AB8500_RTC_WATCH_TSECMID_REG    0x03
#define AB8500_RTC_WATCH_TSECHI_REG     0x04
#define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
#define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
#define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
#define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
#define AB8500_RTC_ALRM_MIN_MID_REG     0x09
#define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
#define AB8500_RTC_STAT_REG             0x0B
#define AB8500_RTC_BKUP_CHG_REG         0x0C
#define AB8500_RTC_FORCE_BKUP_REG       0x0D
#define AB8500_RTC_CALIB_REG            0x0E
#define AB8500_RTC_SWITCH_STAT_REG      0x0F

/* RtcReadRequest bits */
#define RTC_READ_REQUEST                0x01
#define RTC_WRITE_REQUEST               0x02

/* RtcCtrl bits */
#define RTC_ALARM_ENA                   0x04
#define RTC_STATUS_DATA                 0x01

#define COUNTS_PER_SEC                  (0xF000 / 60)

static const u8 ab8500_rtc_time_regs[] = {
        AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
        AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
        AB8500_RTC_WATCH_TSECMID_REG
};

static const u8 ab8500_rtc_alarm_regs[] = {
        AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
        AB8500_RTC_ALRM_MIN_LOW_REG
};

static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        unsigned long timeout = jiffies + HZ;
        int retval, i;
        unsigned long mins, secs;
        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
        u8 value;

        /* Request a data read */
        retval = abx500_set_register_interruptible(dev,
                AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
        if (retval < 0)
                return retval;

        /* Wait for some cycles after enabling the rtc read in ab8500 */
        while (time_before(jiffies, timeout)) {
                retval = abx500_get_register_interruptible(dev,
                        AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
                if (retval < 0)
                        return retval;

                if (!(value & RTC_READ_REQUEST))
                        break;

                usleep_range(1000, 5000);
        }

        /* Read the Watchtime registers */
        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
                retval = abx500_get_register_interruptible(dev,
                        AB8500_RTC, ab8500_rtc_time_regs[i], &value);
                if (retval < 0)
                        return retval;
                buf[i] = value;
        }

        mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];

        secs =  (buf[3] << 8) | buf[4];
        secs =  secs / COUNTS_PER_SEC;
        secs =  secs + (mins * 60);

        rtc_time64_to_tm(secs, tm);
        return 0;
}

static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        int retval, i;
        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
        unsigned long no_secs, no_mins, secs = 0;

        secs = rtc_tm_to_time64(tm);

        no_mins = secs / 60;

        no_secs = secs % 60;
        /* Make the seconds count as per the RTC resolution */
        no_secs = no_secs * COUNTS_PER_SEC;

        buf[4] = no_secs & 0xFF;
        buf[3] = (no_secs >> 8) & 0xFF;

        buf[2] = no_mins & 0xFF;
        buf[1] = (no_mins >> 8) & 0xFF;
        buf[0] = (no_mins >> 16) & 0xFF;

        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
                        ab8500_rtc_time_regs[i], buf[i]);
                if (retval < 0)
                        return retval;
        }

        /* Request a data write */
        return abx500_set_register_interruptible(dev, AB8500_RTC,
                AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
}

static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        int retval, i;
        u8 rtc_ctrl, value;
        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
        unsigned long secs, mins;

        /* Check if the alarm is enabled or not */
        retval = abx500_get_register_interruptible(dev, AB8500_RTC,
                AB8500_RTC_STAT_REG, &rtc_ctrl);
        if (retval < 0)
                return retval;

        if (rtc_ctrl & RTC_ALARM_ENA)
                alarm->enabled = 1;
        else
                alarm->enabled = 0;

        alarm->pending = 0;

        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
                retval = abx500_get_register_interruptible(dev, AB8500_RTC,
                        ab8500_rtc_alarm_regs[i], &value);
                if (retval < 0)
                        return retval;
                buf[i] = value;
        }

        mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
        secs = mins * 60;

        rtc_time64_to_tm(secs, &alarm->time);

        return 0;
}

static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
        return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
                AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
                enabled ? RTC_ALARM_ENA : 0);
}

static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        int retval, i;
        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
        unsigned long mins;

        mins = (unsigned long)rtc_tm_to_time64(&alarm->time) / 60;

        buf[2] = mins & 0xFF;
        buf[1] = (mins >> 8) & 0xFF;
        buf[0] = (mins >> 16) & 0xFF;

        /* Set the alarm time */
        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
                        ab8500_rtc_alarm_regs[i], buf[i]);
                if (retval < 0)
                        return retval;
        }

        return ab8500_rtc_irq_enable(dev, alarm->enabled);
}

static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
{
        int retval;
        u8  rtccal = 0;

        /*
         * Check that the calibration value (which is in units of 0.5
         * parts-per-million) is in the AB8500's range for RtcCalibration
         * register. -128 (0x80) is not permitted because the AB8500 uses
         * a sign-bit rather than two's complement, so 0x80 is just another
         * representation of zero.
         */
        if ((calibration < -127) || (calibration > 127)) {
                dev_err(dev, "RtcCalibration value outside permitted range\n");
                return -EINVAL;
        }

        /*
         * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
         * so need to convert to this sort of representation before writing
         * into RtcCalibration register...
         */
        if (calibration >= 0)
                rtccal = 0x7F & calibration;
        else
                rtccal = ~(calibration - 1) | 0x80;

        retval = abx500_set_register_interruptible(dev, AB8500_RTC,
                        AB8500_RTC_CALIB_REG, rtccal);

        return retval;
}

static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
{
        int retval;
        u8  rtccal = 0;

        retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
                        AB8500_RTC_CALIB_REG, &rtccal);
        if (retval >= 0) {
                /*
                 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
                 * so need to convert value from RtcCalibration register into
                 * a two's complement signed value...
                 */
                if (rtccal & 0x80)
                        *calibration = 0 - (rtccal & 0x7F);
                else
                        *calibration = 0x7F & rtccal;
        }

        return retval;
}

static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        int retval;
        int calibration = 0;

        if (sscanf(buf, " %i ", &calibration) != 1) {
                dev_err(dev, "Failed to store RTC calibration attribute\n");
                return -EINVAL;
        }

        retval = ab8500_rtc_set_calibration(dev, calibration);

        return retval ? retval : count;
}

static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        int  retval = 0;
        int  calibration = 0;

        retval = ab8500_rtc_get_calibration(dev, &calibration);
        if (retval < 0) {
                dev_err(dev, "Failed to read RTC calibration attribute\n");
                sprintf(buf, "0\n");
                return retval;
        }

        return sprintf(buf, "%d\n", calibration);
}

static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
                   ab8500_sysfs_show_rtc_calibration,
                   ab8500_sysfs_store_rtc_calibration);

static struct attribute *ab8500_rtc_attrs[] = {
        &dev_attr_rtc_calibration.attr,
        NULL
};

static const struct attribute_group ab8500_rtc_sysfs_files = {
        .attrs  = ab8500_rtc_attrs,
};

static irqreturn_t rtc_alarm_handler(int irq, void *data)
{
        struct rtc_device *rtc = data;
        unsigned long events = RTC_IRQF | RTC_AF;

        dev_dbg(&rtc->dev, "%s\n", __func__);
        rtc_update_irq(rtc, 1, events);

        return IRQ_HANDLED;
}

static const struct rtc_class_ops ab8500_rtc_ops = {
        .read_time              = ab8500_rtc_read_time,
        .set_time               = ab8500_rtc_set_time,
        .read_alarm             = ab8500_rtc_read_alarm,
        .set_alarm              = ab8500_rtc_set_alarm,
        .alarm_irq_enable       = ab8500_rtc_irq_enable,
};

static const struct platform_device_id ab85xx_rtc_ids[] = {
        { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);

static int ab8500_rtc_probe(struct platform_device *pdev)
{
        const struct platform_device_id *platid = platform_get_device_id(pdev);
        int err;
        struct rtc_device *rtc;
        u8 rtc_ctrl;
        int irq;

        irq = platform_get_irq_byname(pdev, "ALARM");
        if (irq < 0)
                return irq;

        /* For RTC supply test */
        err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
                AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
        if (err < 0)
                return err;

        /* Wait for reset by the PorRtc */
        usleep_range(1000, 5000);

        err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
                AB8500_RTC_STAT_REG, &rtc_ctrl);
        if (err < 0)
                return err;

        /* Check if the RTC Supply fails */
        if (!(rtc_ctrl & RTC_STATUS_DATA)) {
                dev_err(&pdev->dev, "RTC supply failure\n");
                return -ENODEV;
        }

        devm_device_init_wakeup(&pdev->dev);

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

        rtc->ops = (struct rtc_class_ops *)platid->driver_data;

        err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
                        rtc_alarm_handler, IRQF_ONESHOT,
                        "ab8500-rtc", rtc);
        if (err < 0)
                return err;

        devm_pm_set_wake_irq(&pdev->dev, irq);
        platform_set_drvdata(pdev, rtc);

        set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features);
        clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);

        rtc->range_max = (1ULL << 24) * 60 - 1; // 24-bit minutes + 59 secs
        rtc->start_secs = RTC_TIMESTAMP_BEGIN_2000;
        rtc->set_start_time = true;

        err = rtc_add_group(rtc, &ab8500_rtc_sysfs_files);
        if (err)
                return err;

        return devm_rtc_register_device(rtc);
}

static struct platform_driver ab8500_rtc_driver = {
        .driver = {
                .name = "ab8500-rtc",
        },
        .probe  = ab8500_rtc_probe,
        .id_table = ab85xx_rtc_ids,
};

module_platform_driver(ab8500_rtc_driver);

MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
MODULE_DESCRIPTION("AB8500 RTC Driver");
MODULE_LICENSE("GPL v2");