// SPDX-License-Identifier: GPL-2.0-only
/*
 * Motorola CPCAP PMIC RTC driver
 *
 * Based on cpcap-regulator.c from Motorola Linux kernel tree
 * Copyright (C) 2009 Motorola, Inc.
 *
 * Rewritten for mainline kernel
 *  - use DT
 *  - use regmap
 *  - use standard interrupt framework
 *  - use managed device resources
 *  - remove custom "secure clock daemon" helpers
 *
 * Copyright (C) 2017 Sebastian Reichel <sre@kernel.org>
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/err.h>
#include <linux/regmap.h>
#include <linux/mfd/motorola-cpcap.h>
#include <linux/slab.h>
#include <linux/sched.h>

#define SECS_PER_DAY 86400
#define DAY_MASK  0x7FFF
#define TOD1_MASK 0x00FF
#define TOD2_MASK 0x01FF

struct cpcap_time {
        int day;
        int tod1;
        int tod2;
};

struct cpcap_rtc {
        struct regmap *regmap;
        struct rtc_device *rtc_dev;
        u16 vendor;
        int alarm_irq;
        bool alarm_enabled;
        int update_irq;
        bool update_enabled;
};

static void cpcap2rtc_time(struct rtc_time *rtc, struct cpcap_time *cpcap)
{
        unsigned long int tod;
        unsigned long int time;

        tod = (cpcap->tod1 & TOD1_MASK) | ((cpcap->tod2 & TOD2_MASK) << 8);
        time = tod + ((cpcap->day & DAY_MASK) * SECS_PER_DAY);

        rtc_time64_to_tm(time, rtc);
}

static void rtc2cpcap_time(struct cpcap_time *cpcap, struct rtc_time *rtc)
{
        unsigned long time;

        time = rtc_tm_to_time64(rtc);

        cpcap->day = time / SECS_PER_DAY;
        time %= SECS_PER_DAY;
        cpcap->tod2 = (time >> 8) & TOD2_MASK;
        cpcap->tod1 = time & TOD1_MASK;
}

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

        if (rtc->alarm_enabled == enabled)
                return 0;

        if (enabled)
                enable_irq(rtc->alarm_irq);
        else
                disable_irq(rtc->alarm_irq);

        rtc->alarm_enabled = !!enabled;

        return 0;
}

static int cpcap_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct cpcap_rtc *rtc;
        struct cpcap_time cpcap_tm;
        int temp_tod2;
        int ret;

        rtc = dev_get_drvdata(dev);

        ret = regmap_read(rtc->regmap, CPCAP_REG_TOD2, &temp_tod2);
        ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
        ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD1, &cpcap_tm.tod1);
        ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD2, &cpcap_tm.tod2);

        if (temp_tod2 > cpcap_tm.tod2)
                ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);

        if (ret) {
                dev_err(dev, "Failed to read time\n");
                return -EIO;
        }

        cpcap2rtc_time(tm, &cpcap_tm);

        return 0;
}

static int cpcap_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct cpcap_rtc *rtc;
        struct cpcap_time cpcap_tm;
        int ret = 0;

        rtc = dev_get_drvdata(dev);

        rtc2cpcap_time(&cpcap_tm, tm);

        if (rtc->alarm_enabled)
                disable_irq(rtc->alarm_irq);
        if (rtc->update_enabled)
                disable_irq(rtc->update_irq);

        if (rtc->vendor == CPCAP_VENDOR_ST) {
                /* The TOD1 and TOD2 registers MUST be written in this order
                 * for the change to properly set.
                 */
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
                                          TOD1_MASK, cpcap_tm.tod1);
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
                                          TOD2_MASK, cpcap_tm.tod2);
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
                                          DAY_MASK, cpcap_tm.day);
        } else {
                /* Clearing the upper lower 8 bits of the TOD guarantees that
                 * the upper half of TOD (TOD2) will not increment for 0xFF RTC
                 * ticks (255 seconds).  During this time we can safely write
                 * to DAY, TOD2, then TOD1 (in that order) and expect RTC to be
                 * synchronized to the exact time requested upon the final write
                 * to TOD1.
                 */
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
                                          TOD1_MASK, 0);
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
                                          DAY_MASK, cpcap_tm.day);
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
                                          TOD2_MASK, cpcap_tm.tod2);
                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
                                          TOD1_MASK, cpcap_tm.tod1);
        }

        if (rtc->update_enabled)
                enable_irq(rtc->update_irq);
        if (rtc->alarm_enabled)
                enable_irq(rtc->alarm_irq);

        return ret;
}

static int cpcap_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct cpcap_rtc *rtc;
        struct cpcap_time cpcap_tm;
        int ret;

        rtc = dev_get_drvdata(dev);

        alrm->enabled = rtc->alarm_enabled;

        ret = regmap_read(rtc->regmap, CPCAP_REG_DAYA, &cpcap_tm.day);
        ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA2, &cpcap_tm.tod2);
        ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA1, &cpcap_tm.tod1);

        if (ret) {
                dev_err(dev, "Failed to read time\n");
                return -EIO;
        }

        cpcap2rtc_time(&alrm->time, &cpcap_tm);
        return rtc_valid_tm(&alrm->time);
}

static int cpcap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct cpcap_rtc *rtc;
        struct cpcap_time cpcap_tm;
        int ret;

        rtc = dev_get_drvdata(dev);

        rtc2cpcap_time(&cpcap_tm, &alrm->time);

        if (rtc->alarm_enabled)
                disable_irq(rtc->alarm_irq);

        ret = regmap_update_bits(rtc->regmap, CPCAP_REG_DAYA, DAY_MASK,
                                 cpcap_tm.day);
        ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA2, TOD2_MASK,
                                  cpcap_tm.tod2);
        ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA1, TOD1_MASK,
                                  cpcap_tm.tod1);

        if (!ret) {
                enable_irq(rtc->alarm_irq);
                rtc->alarm_enabled = true;
        }

        return ret;
}

static const struct rtc_class_ops cpcap_rtc_ops = {
        .read_time              = cpcap_rtc_read_time,
        .set_time               = cpcap_rtc_set_time,
        .read_alarm             = cpcap_rtc_read_alarm,
        .set_alarm              = cpcap_rtc_set_alarm,
        .alarm_irq_enable       = cpcap_rtc_alarm_irq_enable,
};

static irqreturn_t cpcap_rtc_alarm_irq(int irq, void *data)
{
        struct cpcap_rtc *rtc = data;

        rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
        return IRQ_HANDLED;
}

static irqreturn_t cpcap_rtc_update_irq(int irq, void *data)
{
        struct cpcap_rtc *rtc = data;

        rtc_update_irq(rtc->rtc_dev, 1, RTC_UF | RTC_IRQF);
        return IRQ_HANDLED;
}

static int cpcap_rtc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cpcap_rtc *rtc;
        int err;

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

        rtc->regmap = dev_get_regmap(dev->parent, NULL);
        if (!rtc->regmap)
                return -ENODEV;

        platform_set_drvdata(pdev, rtc);
        rtc->rtc_dev = devm_rtc_allocate_device(dev);
        if (IS_ERR(rtc->rtc_dev))
                return PTR_ERR(rtc->rtc_dev);

        rtc->rtc_dev->ops = &cpcap_rtc_ops;
        rtc->rtc_dev->range_max = (timeu64_t) (DAY_MASK + 1) * SECS_PER_DAY - 1;

        err = cpcap_get_vendor(dev, rtc->regmap, &rtc->vendor);
        if (err)
                return err;

        rtc->alarm_irq = platform_get_irq(pdev, 0);
        err = devm_request_threaded_irq(dev, rtc->alarm_irq, NULL,
                                        cpcap_rtc_alarm_irq,
                                        IRQF_TRIGGER_NONE | IRQF_ONESHOT,
                                        "rtc_alarm", rtc);
        if (err) {
                dev_err(dev, "Could not request alarm irq: %d\n", err);
                return err;
        }
        disable_irq(rtc->alarm_irq);

        /* Stock Android uses the 1 Hz interrupt for "secure clock daemon",
         * which is not supported by the mainline kernel. The mainline kernel
         * does not use the irq at the moment, but we explicitly request and
         * disable it, so that its masked and does not wake up the processor
         * every second.
         */
        rtc->update_irq = platform_get_irq(pdev, 1);
        err = devm_request_threaded_irq(dev, rtc->update_irq, NULL,
                                        cpcap_rtc_update_irq,
                                        IRQF_TRIGGER_NONE | IRQF_ONESHOT,
                                        "rtc_1hz", rtc);
        if (err) {
                dev_err(dev, "Could not request update irq: %d\n", err);
                return err;
        }
        disable_irq(rtc->update_irq);

        err = device_init_wakeup(dev, true);
        if (err) {
                dev_err(dev, "wakeup initialization failed (%d)\n", err);
                /* ignore error and continue without wakeup support */
        }

        return devm_rtc_register_device(rtc->rtc_dev);
}

static const struct of_device_id cpcap_rtc_of_match[] = {
        { .compatible = "motorola,cpcap-rtc", },
        {},
};
MODULE_DEVICE_TABLE(of, cpcap_rtc_of_match);

static struct platform_driver cpcap_rtc_driver = {
        .probe          = cpcap_rtc_probe,
        .driver         = {
                .name   = "cpcap-rtc",
                .of_match_table = cpcap_rtc_of_match,
        },
};

module_platform_driver(cpcap_rtc_driver);

MODULE_DESCRIPTION("CPCAP RTC driver");
MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
MODULE_LICENSE("GPL");