// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Oki MSM6242 RTC Driver
 *
 *  Copyright 2009 Geert Uytterhoeven
 *
 *  Based on the A2000 TOD code in arch/m68k/amiga/config.c
 *  Copyright (C) 1993 Hamish Macdonald
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>


enum {
        MSM6242_SECOND1         = 0x0,  /* 1-second digit register */
        MSM6242_SECOND10        = 0x1,  /* 10-second digit register */
        MSM6242_MINUTE1         = 0x2,  /* 1-minute digit register */
        MSM6242_MINUTE10        = 0x3,  /* 10-minute digit register */
        MSM6242_HOUR1           = 0x4,  /* 1-hour digit register */
        MSM6242_HOUR10          = 0x5,  /* PM/AM, 10-hour digit register */
        MSM6242_DAY1            = 0x6,  /* 1-day digit register */
        MSM6242_DAY10           = 0x7,  /* 10-day digit register */
        MSM6242_MONTH1          = 0x8,  /* 1-month digit register */
        MSM6242_MONTH10         = 0x9,  /* 10-month digit register */
        MSM6242_YEAR1           = 0xa,  /* 1-year digit register */
        MSM6242_YEAR10          = 0xb,  /* 10-year digit register */
        MSM6242_WEEK            = 0xc,  /* Week register */
        MSM6242_CD              = 0xd,  /* Control Register D */
        MSM6242_CE              = 0xe,  /* Control Register E */
        MSM6242_CF              = 0xf,  /* Control Register F */
};

#define MSM6242_HOUR10_AM       (0 << 2)
#define MSM6242_HOUR10_PM       (1 << 2)
#define MSM6242_HOUR10_HR_MASK  (3 << 0)

#define MSM6242_WEEK_SUNDAY     0
#define MSM6242_WEEK_MONDAY     1
#define MSM6242_WEEK_TUESDAY    2
#define MSM6242_WEEK_WEDNESDAY  3
#define MSM6242_WEEK_THURSDAY   4
#define MSM6242_WEEK_FRIDAY     5
#define MSM6242_WEEK_SATURDAY   6

#define MSM6242_CD_30_S_ADJ     (1 << 3)        /* 30-second adjustment */
#define MSM6242_CD_IRQ_FLAG     (1 << 2)
#define MSM6242_CD_BUSY         (1 << 1)
#define MSM6242_CD_HOLD         (1 << 0)

#define MSM6242_CE_T_MASK       (3 << 2)
#define MSM6242_CE_T_64HZ       (0 << 2)        /* period 1/64 second */
#define MSM6242_CE_T_1HZ        (1 << 2)        /* period 1 second */
#define MSM6242_CE_T_1MINUTE    (2 << 2)        /* period 1 minute */
#define MSM6242_CE_T_1HOUR      (3 << 2)        /* period 1 hour */

#define MSM6242_CE_ITRPT_STND   (1 << 1)
#define MSM6242_CE_MASK         (1 << 0)        /* STD.P output control */

#define MSM6242_CF_TEST         (1 << 3)
#define MSM6242_CF_12H          (0 << 2)
#define MSM6242_CF_24H          (1 << 2)
#define MSM6242_CF_STOP         (1 << 1)
#define MSM6242_CF_REST         (1 << 0)        /* reset */


struct msm6242_priv {
        u32 __iomem *regs;
        struct rtc_device *rtc;
};

static inline unsigned int msm6242_read(struct msm6242_priv *priv,
                                       unsigned int reg)
{
        return __raw_readl(&priv->regs[reg]) & 0xf;
}

static inline void msm6242_write(struct msm6242_priv *priv, unsigned int val,
                                unsigned int reg)
{
        __raw_writel(val, &priv->regs[reg]);
}

static void msm6242_lock(struct msm6242_priv *priv)
{
        int cnt = 5;

        msm6242_write(priv, MSM6242_CD_HOLD|MSM6242_CD_IRQ_FLAG, MSM6242_CD);

        while ((msm6242_read(priv, MSM6242_CD) & MSM6242_CD_BUSY) && cnt) {
                msm6242_write(priv, MSM6242_CD_IRQ_FLAG, MSM6242_CD);
                udelay(70);
                msm6242_write(priv, MSM6242_CD_HOLD|MSM6242_CD_IRQ_FLAG, MSM6242_CD);
                cnt--;
        }

        if (!cnt)
                pr_warn("timed out waiting for RTC (0x%x)\n",
                        msm6242_read(priv, MSM6242_CD));
}

static void msm6242_unlock(struct msm6242_priv *priv)
{
        msm6242_write(priv, MSM6242_CD_IRQ_FLAG, MSM6242_CD);
}

static int msm6242_read_time(struct device *dev, struct rtc_time *tm)
{
        struct msm6242_priv *priv = dev_get_drvdata(dev);

        msm6242_lock(priv);

        tm->tm_sec  = msm6242_read(priv, MSM6242_SECOND10) * 10 +
                      msm6242_read(priv, MSM6242_SECOND1);
        tm->tm_min  = msm6242_read(priv, MSM6242_MINUTE10) * 10 +
                      msm6242_read(priv, MSM6242_MINUTE1);
        tm->tm_hour = (msm6242_read(priv, MSM6242_HOUR10) &
                       MSM6242_HOUR10_HR_MASK) * 10 +
                      msm6242_read(priv, MSM6242_HOUR1);
        tm->tm_mday = msm6242_read(priv, MSM6242_DAY10) * 10 +
                      msm6242_read(priv, MSM6242_DAY1);
        tm->tm_wday = msm6242_read(priv, MSM6242_WEEK);
        tm->tm_mon  = msm6242_read(priv, MSM6242_MONTH10) * 10 +
                      msm6242_read(priv, MSM6242_MONTH1) - 1;
        tm->tm_year = msm6242_read(priv, MSM6242_YEAR10) * 10 +
                      msm6242_read(priv, MSM6242_YEAR1);
        if (tm->tm_year <= 69)
                tm->tm_year += 100;

        if (!(msm6242_read(priv, MSM6242_CF) & MSM6242_CF_24H)) {
                unsigned int pm = msm6242_read(priv, MSM6242_HOUR10) &
                                  MSM6242_HOUR10_PM;
                if (!pm && tm->tm_hour == 12)
                        tm->tm_hour = 0;
                else if (pm && tm->tm_hour != 12)
                        tm->tm_hour += 12;
        }

        msm6242_unlock(priv);

        return 0;
}

static int msm6242_set_time(struct device *dev, struct rtc_time *tm)
{
        struct msm6242_priv *priv = dev_get_drvdata(dev);

        msm6242_lock(priv);

        msm6242_write(priv, tm->tm_sec / 10, MSM6242_SECOND10);
        msm6242_write(priv, tm->tm_sec % 10, MSM6242_SECOND1);
        msm6242_write(priv, tm->tm_min / 10, MSM6242_MINUTE10);
        msm6242_write(priv, tm->tm_min % 10, MSM6242_MINUTE1);
        if (msm6242_read(priv, MSM6242_CF) & MSM6242_CF_24H)
                msm6242_write(priv, tm->tm_hour / 10, MSM6242_HOUR10);
        else if (tm->tm_hour >= 12)
                msm6242_write(priv, MSM6242_HOUR10_PM + (tm->tm_hour - 12) / 10,
                              MSM6242_HOUR10);
        else
                msm6242_write(priv, tm->tm_hour / 10, MSM6242_HOUR10);
        msm6242_write(priv, tm->tm_hour % 10, MSM6242_HOUR1);
        msm6242_write(priv, tm->tm_mday / 10, MSM6242_DAY10);
        msm6242_write(priv, tm->tm_mday % 10, MSM6242_DAY1);
        if (tm->tm_wday != -1)
                msm6242_write(priv, tm->tm_wday, MSM6242_WEEK);
        msm6242_write(priv, (tm->tm_mon + 1) / 10, MSM6242_MONTH10);
        msm6242_write(priv, (tm->tm_mon + 1) % 10, MSM6242_MONTH1);
        if (tm->tm_year >= 100)
                tm->tm_year -= 100;
        msm6242_write(priv, tm->tm_year / 10, MSM6242_YEAR10);
        msm6242_write(priv, tm->tm_year % 10, MSM6242_YEAR1);

        msm6242_unlock(priv);
        return 0;
}

static const struct rtc_class_ops msm6242_rtc_ops = {
        .read_time      = msm6242_read_time,
        .set_time       = msm6242_set_time,
};

static int __init msm6242_rtc_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct msm6242_priv *priv;
        struct rtc_device *rtc;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENODEV;

        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->regs = devm_ioremap(&pdev->dev, res->start, resource_size(res));
        if (!priv->regs)
                return -ENOMEM;
        platform_set_drvdata(pdev, priv);

        rtc = devm_rtc_device_register(&pdev->dev, "rtc-msm6242",
                                &msm6242_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc))
                return PTR_ERR(rtc);

        priv->rtc = rtc;
        return 0;
}

static struct platform_driver msm6242_rtc_driver = {
        .driver = {
                .name   = "rtc-msm6242",
        },
};

module_platform_driver_probe(msm6242_rtc_driver, msm6242_rtc_probe);

MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Oki MSM6242 RTC driver");
MODULE_ALIAS("platform:rtc-msm6242");