// SPDX-License-Identifier: GPL-2.0-only
/*
 * Real Time Clock driver for Marvell 88PM860x PMIC
 *
 * Copyright (c) 2010 Marvell International Ltd.
 * Author:      Haojian Zhuang <haojian.zhuang@marvell.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/mfd/core.h>
#include <linux/mfd/88pm860x.h>

#define VRTC_CALIBRATION

struct pm860x_rtc_info {
        struct pm860x_chip      *chip;
        struct i2c_client       *i2c;
        struct rtc_device       *rtc_dev;
        struct device           *dev;
        struct delayed_work     calib_work;

        int                     irq;
        int                     vrtc;
};

#define REG_VRTC_MEAS1          0x7D

#define REG0_ADDR               0xB0
#define REG1_ADDR               0xB2
#define REG2_ADDR               0xB4
#define REG3_ADDR               0xB6

#define REG0_DATA               0xB1
#define REG1_DATA               0xB3
#define REG2_DATA               0xB5
#define REG3_DATA               0xB7

/* bit definitions of Measurement Enable Register 2 (0x51) */
#define MEAS2_VRTC              (1 << 0)

/* bit definitions of RTC Register 1 (0xA0) */
#define ALARM_EN                (1 << 3)
#define ALARM_WAKEUP            (1 << 4)
#define ALARM                   (1 << 5)
#define RTC1_USE_XO             (1 << 7)

#define VRTC_CALIB_INTERVAL     (HZ * 60 * 10)          /* 10 minutes */

static irqreturn_t rtc_update_handler(int irq, void *data)
{
        struct pm860x_rtc_info *info = (struct pm860x_rtc_info *)data;
        int mask;

        mask = ALARM | ALARM_WAKEUP;
        pm860x_set_bits(info->i2c, PM8607_RTC1, mask | ALARM_EN, mask);
        rtc_update_irq(info->rtc_dev, 1, RTC_AF);
        return IRQ_HANDLED;
}

static int pm860x_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct pm860x_rtc_info *info = dev_get_drvdata(dev);

        if (enabled)
                pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, ALARM_EN);
        else
                pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, 0);
        return 0;
}

static int pm860x_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct pm860x_rtc_info *info = dev_get_drvdata(dev);
        unsigned char buf[8];
        unsigned long ticks, base, data;

        pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
        dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
                buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
        base = ((unsigned long)buf[1] << 24) | (buf[3] << 16) |
                (buf[5] << 8) | buf[7];

        /* load 32-bit read-only counter */
        pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
        data = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
                (buf[1] << 8) | buf[0];
        ticks = base + data;
        dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
                base, data, ticks);

        rtc_time64_to_tm(ticks, tm);

        return 0;
}

static int pm860x_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct pm860x_rtc_info *info = dev_get_drvdata(dev);
        unsigned char buf[4];
        unsigned long ticks, base, data;

        ticks = rtc_tm_to_time64(tm);

        /* load 32-bit read-only counter */
        pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
        data = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
                (buf[1] << 8) | buf[0];
        base = ticks - data;
        dev_dbg(info->dev, "set base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
                base, data, ticks);

        pm860x_page_reg_write(info->i2c, REG0_DATA, (base >> 24) & 0xFF);
        pm860x_page_reg_write(info->i2c, REG1_DATA, (base >> 16) & 0xFF);
        pm860x_page_reg_write(info->i2c, REG2_DATA, (base >> 8) & 0xFF);
        pm860x_page_reg_write(info->i2c, REG3_DATA, base & 0xFF);

        return 0;
}

static int pm860x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct pm860x_rtc_info *info = dev_get_drvdata(dev);
        unsigned char buf[8];
        unsigned long ticks, base, data;
        int ret;

        pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
        dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
                buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
        base = ((unsigned long)buf[1] << 24) | (buf[3] << 16) |
                (buf[5] << 8) | buf[7];

        pm860x_bulk_read(info->i2c, PM8607_RTC_EXPIRE1, 4, buf);
        data = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
                (buf[1] << 8) | buf[0];
        ticks = base + data;
        dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
                base, data, ticks);

        rtc_time64_to_tm(ticks, &alrm->time);
        ret = pm860x_reg_read(info->i2c, PM8607_RTC1);
        alrm->enabled = (ret & ALARM_EN) ? 1 : 0;
        alrm->pending = (ret & (ALARM | ALARM_WAKEUP)) ? 1 : 0;
        return 0;
}

static int pm860x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct pm860x_rtc_info *info = dev_get_drvdata(dev);
        unsigned long ticks, base, data;
        unsigned char buf[8];
        int mask;

        pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, 0);

        pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
        dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
                buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
        base = ((unsigned long)buf[1] << 24) | (buf[3] << 16) |
                (buf[5] << 8) | buf[7];

        ticks = rtc_tm_to_time64(&alrm->time);
        data = ticks - base;

        buf[0] = data & 0xff;
        buf[1] = (data >> 8) & 0xff;
        buf[2] = (data >> 16) & 0xff;
        buf[3] = (data >> 24) & 0xff;
        pm860x_bulk_write(info->i2c, PM8607_RTC_EXPIRE1, 4, buf);
        if (alrm->enabled) {
                mask = ALARM | ALARM_WAKEUP | ALARM_EN;
                pm860x_set_bits(info->i2c, PM8607_RTC1, mask, mask);
        } else {
                mask = ALARM | ALARM_WAKEUP | ALARM_EN;
                pm860x_set_bits(info->i2c, PM8607_RTC1, mask,
                                ALARM | ALARM_WAKEUP);
        }
        return 0;
}

static const struct rtc_class_ops pm860x_rtc_ops = {
        .read_time      = pm860x_rtc_read_time,
        .set_time       = pm860x_rtc_set_time,
        .read_alarm     = pm860x_rtc_read_alarm,
        .set_alarm      = pm860x_rtc_set_alarm,
        .alarm_irq_enable = pm860x_rtc_alarm_irq_enable,
};

#ifdef VRTC_CALIBRATION
static void calibrate_vrtc_work(struct work_struct *work)
{
        struct pm860x_rtc_info *info = container_of(work,
                struct pm860x_rtc_info, calib_work.work);
        unsigned char buf[2];
        unsigned int sum, data, mean, vrtc_set;
        int i;

        for (i = 0, sum = 0; i < 16; i++) {
                msleep(100);
                pm860x_bulk_read(info->i2c, REG_VRTC_MEAS1, 2, buf);
                data = (buf[0] << 4) | buf[1];
                data = (data * 5400) >> 12;     /* convert to mv */
                sum += data;
        }
        mean = sum >> 4;
        vrtc_set = 2700 + (info->vrtc & 0x3) * 200;
        dev_dbg(info->dev, "mean:%d, vrtc_set:%d\n", mean, vrtc_set);

        sum = pm860x_reg_read(info->i2c, PM8607_RTC_MISC1);
        data = sum & 0x3;
        if ((mean + 200) < vrtc_set) {
                /* try higher voltage */
                if (++data == 4)
                        goto out;
                data = (sum & 0xf8) | (data & 0x3);
                pm860x_reg_write(info->i2c, PM8607_RTC_MISC1, data);
        } else if ((mean - 200) > vrtc_set) {
                /* try lower voltage */
                if (data-- == 0)
                        goto out;
                data = (sum & 0xf8) | (data & 0x3);
                pm860x_reg_write(info->i2c, PM8607_RTC_MISC1, data);
        } else
                goto out;
        dev_dbg(info->dev, "set 0x%x to RTC_MISC1\n", data);
        /* trigger next calibration since VRTC is updated */
        schedule_delayed_work(&info->calib_work, VRTC_CALIB_INTERVAL);
        return;
out:
        /* disable measurement */
        pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, 0);
        dev_dbg(info->dev, "finish VRTC calibration\n");
        return;
}
#endif

#ifdef CONFIG_OF
static int pm860x_rtc_dt_init(struct platform_device *pdev,
                              struct pm860x_rtc_info *info)
{
        struct device_node *np = pdev->dev.parent->of_node;
        int ret;
        if (!np)
                return -ENODEV;
        np = of_get_child_by_name(np, "rtc");
        if (!np) {
                dev_err(&pdev->dev, "failed to find rtc node\n");
                return -ENODEV;
        }
        ret = of_property_read_u32(np, "marvell,88pm860x-vrtc", &info->vrtc);
        if (ret)
                info->vrtc = 0;
        of_node_put(np);
        return 0;
}
#else
#define pm860x_rtc_dt_init(x, y)        do { } while (0)
#endif

static int pm860x_rtc_probe(struct platform_device *pdev)
{
        struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);
        struct pm860x_rtc_info *info;
        int ret;

        info = devm_kzalloc(&pdev->dev, sizeof(struct pm860x_rtc_info),
                            GFP_KERNEL);
        if (!info)
                return -ENOMEM;
        info->irq = platform_get_irq(pdev, 0);
        if (info->irq < 0)
                return info->irq;

        info->chip = chip;
        info->i2c = (chip->id == CHIP_PM8607) ? chip->client : chip->companion;
        info->dev = &pdev->dev;
        dev_set_drvdata(&pdev->dev, info);

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

        ret = devm_request_threaded_irq(&pdev->dev, info->irq, NULL,
                                        rtc_update_handler, IRQF_ONESHOT, "rtc",
                                        info);
        if (ret < 0) {
                dev_err(chip->dev, "Failed to request IRQ: #%d: %d\n",
                        info->irq, ret);
                return ret;
        }

        /* set addresses of 32-bit base value for RTC time */
        pm860x_page_reg_write(info->i2c, REG0_ADDR, REG0_DATA);
        pm860x_page_reg_write(info->i2c, REG1_ADDR, REG1_DATA);
        pm860x_page_reg_write(info->i2c, REG2_ADDR, REG2_DATA);
        pm860x_page_reg_write(info->i2c, REG3_ADDR, REG3_DATA);

        pm860x_rtc_dt_init(pdev, info);

        info->rtc_dev->ops = &pm860x_rtc_ops;
        info->rtc_dev->range_max = U32_MAX;

        ret = devm_rtc_register_device(info->rtc_dev);
        if (ret)
                return ret;

        /*
         * enable internal XO instead of internal 3.25MHz clock since it can
         * free running in PMIC power-down state.
         */
        pm860x_set_bits(info->i2c, PM8607_RTC1, RTC1_USE_XO, RTC1_USE_XO);

#ifdef VRTC_CALIBRATION
        /* <00> -- 2.7V, <01> -- 2.9V, <10> -- 3.1V, <11> -- 3.3V */
        pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, MEAS2_VRTC);

        /* calibrate VRTC */
        INIT_DELAYED_WORK(&info->calib_work, calibrate_vrtc_work);
        schedule_delayed_work(&info->calib_work, VRTC_CALIB_INTERVAL);
#endif  /* VRTC_CALIBRATION */

        device_init_wakeup(&pdev->dev, true);

        return 0;
}

static void pm860x_rtc_remove(struct platform_device *pdev)
{
        struct pm860x_rtc_info *info = platform_get_drvdata(pdev);

#ifdef VRTC_CALIBRATION
        cancel_delayed_work_sync(&info->calib_work);
        /* disable measurement */
        pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, 0);
#endif  /* VRTC_CALIBRATION */
}

#ifdef CONFIG_PM_SLEEP
static int pm860x_rtc_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);

        if (device_may_wakeup(dev))
                chip->wakeup_flag |= 1 << PM8607_IRQ_RTC;
        return 0;
}
static int pm860x_rtc_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);

        if (device_may_wakeup(dev))
                chip->wakeup_flag &= ~(1 << PM8607_IRQ_RTC);
        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(pm860x_rtc_pm_ops, pm860x_rtc_suspend, pm860x_rtc_resume);

static struct platform_driver pm860x_rtc_driver = {
        .driver         = {
                .name   = "88pm860x-rtc",
                .pm     = &pm860x_rtc_pm_ops,
        },
        .probe          = pm860x_rtc_probe,
        .remove         = pm860x_rtc_remove,
};

module_platform_driver(pm860x_rtc_driver);

MODULE_DESCRIPTION("Marvell 88PM860x RTC driver");
MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
MODULE_LICENSE("GPL");