/*
 * drivers/rtc/rtc-pl031.c
 *
 * Real Time Clock interface for ARM AMBA PrimeCell 031 RTC
 *
 * Author: Deepak Saxena <dsaxena@plexity.net>
 *
 * Copyright 2006 (c) MontaVista Software, Inc.
 *
 * Author: Mian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>
 * Copyright 2010 (c) ST-Ericsson AB
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/amba/bus.h>
#include <linux/io.h>
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/slab.h>

/*
 * Register definitions
 */
#define RTC_DR          0x00    /* Data read register */
#define RTC_MR          0x04    /* Match register */
#define RTC_LR          0x08    /* Data load register */
#define RTC_CR          0x0c    /* Control register */
#define RTC_IMSC        0x10    /* Interrupt mask and set register */
#define RTC_RIS         0x14    /* Raw interrupt status register */
#define RTC_MIS         0x18    /* Masked interrupt status register */
#define RTC_ICR         0x1c    /* Interrupt clear register */
/* ST variants have additional timer functionality */
#define RTC_TDR         0x20    /* Timer data read register */
#define RTC_TLR         0x24    /* Timer data load register */
#define RTC_TCR         0x28    /* Timer control register */
#define RTC_YDR         0x30    /* Year data read register */
#define RTC_YMR         0x34    /* Year match register */
#define RTC_YLR         0x38    /* Year data load register */

#define RTC_CR_CWEN     (1 << 26)       /* Clockwatch enable bit */

#define RTC_TCR_EN      (1 << 1) /* Periodic timer enable bit */

/* Common bit definitions for Interrupt status and control registers */
#define RTC_BIT_AI      (1 << 0) /* Alarm interrupt bit */
#define RTC_BIT_PI      (1 << 1) /* Periodic interrupt bit. ST variants only. */

/* Common bit definations for ST v2 for reading/writing time */
#define RTC_SEC_SHIFT 0
#define RTC_SEC_MASK (0x3F << RTC_SEC_SHIFT) /* Second [0-59] */
#define RTC_MIN_SHIFT 6
#define RTC_MIN_MASK (0x3F << RTC_MIN_SHIFT) /* Minute [0-59] */
#define RTC_HOUR_SHIFT 12
#define RTC_HOUR_MASK (0x1F << RTC_HOUR_SHIFT) /* Hour [0-23] */
#define RTC_WDAY_SHIFT 17
#define RTC_WDAY_MASK (0x7 << RTC_WDAY_SHIFT) /* Day of Week [1-7] 1=Sunday */
#define RTC_MDAY_SHIFT 20
#define RTC_MDAY_MASK (0x1F << RTC_MDAY_SHIFT) /* Day of Month [1-31] */
#define RTC_MON_SHIFT 25
#define RTC_MON_MASK (0xF << RTC_MON_SHIFT) /* Month [1-12] 1=January */

#define RTC_TIMER_FREQ 32768

struct pl031_local {
        struct rtc_device *rtc;
        void __iomem *base;
        u8 hw_designer;
        u8 hw_revision:4;
};

static int pl031_alarm_irq_enable(struct device *dev,
        unsigned int enabled)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);
        unsigned long imsc;

        /* Clear any pending alarm interrupts. */
        writel(RTC_BIT_AI, ldata->base + RTC_ICR);

        imsc = readl(ldata->base + RTC_IMSC);

        if (enabled == 1)
                writel(imsc | RTC_BIT_AI, ldata->base + RTC_IMSC);
        else
                writel(imsc & ~RTC_BIT_AI, ldata->base + RTC_IMSC);

        return 0;
}

/*
 * Convert Gregorian date to ST v2 RTC format.
 */
static int pl031_stv2_tm_to_time(struct device *dev,
                                 struct rtc_time *tm, unsigned long *st_time,
        unsigned long *bcd_year)
{
        int year = tm->tm_year + 1900;
        int wday = tm->tm_wday;

        /* wday masking is not working in hardware so wday must be valid */
        if (wday < -1 || wday > 6) {
                dev_err(dev, "invalid wday value %d\n", tm->tm_wday);
                return -EINVAL;
        } else if (wday == -1) {
                /* wday is not provided, calculate it here */
                unsigned long time;
                struct rtc_time calc_tm;

                rtc_tm_to_time(tm, &time);
                rtc_time_to_tm(time, &calc_tm);
                wday = calc_tm.tm_wday;
        }

        *bcd_year = (bin2bcd(year % 100) | bin2bcd(year / 100) << 8);

        *st_time = ((tm->tm_mon + 1) << RTC_MON_SHIFT)
                        |       (tm->tm_mday << RTC_MDAY_SHIFT)
                        |       ((wday + 1) << RTC_WDAY_SHIFT)
                        |       (tm->tm_hour << RTC_HOUR_SHIFT)
                        |       (tm->tm_min << RTC_MIN_SHIFT)
                        |       (tm->tm_sec << RTC_SEC_SHIFT);

        return 0;
}

/*
 * Convert ST v2 RTC format to Gregorian date.
 */
static int pl031_stv2_time_to_tm(unsigned long st_time, unsigned long bcd_year,
        struct rtc_time *tm)
{
        tm->tm_year = bcd2bin(bcd_year) + (bcd2bin(bcd_year >> 8) * 100);
        tm->tm_mon  = ((st_time & RTC_MON_MASK) >> RTC_MON_SHIFT) - 1;
        tm->tm_mday = ((st_time & RTC_MDAY_MASK) >> RTC_MDAY_SHIFT);
        tm->tm_wday = ((st_time & RTC_WDAY_MASK) >> RTC_WDAY_SHIFT) - 1;
        tm->tm_hour = ((st_time & RTC_HOUR_MASK) >> RTC_HOUR_SHIFT);
        tm->tm_min  = ((st_time & RTC_MIN_MASK) >> RTC_MIN_SHIFT);
        tm->tm_sec  = ((st_time & RTC_SEC_MASK) >> RTC_SEC_SHIFT);

        tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
        tm->tm_year -= 1900;

        return 0;
}

static int pl031_stv2_read_time(struct device *dev, struct rtc_time *tm)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);

        pl031_stv2_time_to_tm(readl(ldata->base + RTC_DR),
                        readl(ldata->base + RTC_YDR), tm);

        return 0;
}

static int pl031_stv2_set_time(struct device *dev, struct rtc_time *tm)
{
        unsigned long time;
        unsigned long bcd_year;
        struct pl031_local *ldata = dev_get_drvdata(dev);
        int ret;

        ret = pl031_stv2_tm_to_time(dev, tm, &time, &bcd_year);
        if (ret == 0) {
                writel(bcd_year, ldata->base + RTC_YLR);
                writel(time, ldata->base + RTC_LR);
        }

        return ret;
}

static int pl031_stv2_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);
        int ret;

        ret = pl031_stv2_time_to_tm(readl(ldata->base + RTC_MR),
                        readl(ldata->base + RTC_YMR), &alarm->time);

        alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
        alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;

        return ret;
}

static int pl031_stv2_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);
        unsigned long time;
        unsigned long bcd_year;
        int ret;

        /* At the moment, we can only deal with non-wildcarded alarm times. */
        ret = rtc_valid_tm(&alarm->time);
        if (ret == 0) {
                ret = pl031_stv2_tm_to_time(dev, &alarm->time,
                                            &time, &bcd_year);
                if (ret == 0) {
                        writel(bcd_year, ldata->base + RTC_YMR);
                        writel(time, ldata->base + RTC_MR);

                        pl031_alarm_irq_enable(dev, alarm->enabled);
                }
        }

        return ret;
}

static irqreturn_t pl031_interrupt(int irq, void *dev_id)
{
        struct pl031_local *ldata = dev_id;
        unsigned long rtcmis;
        unsigned long events = 0;

        rtcmis = readl(ldata->base + RTC_MIS);
        if (rtcmis) {
                writel(rtcmis, ldata->base + RTC_ICR);

                if (rtcmis & RTC_BIT_AI)
                        events |= (RTC_AF | RTC_IRQF);

                /* Timer interrupt is only available in ST variants */
                if ((rtcmis & RTC_BIT_PI) &&
                        (ldata->hw_designer == AMBA_VENDOR_ST))
                        events |= (RTC_PF | RTC_IRQF);

                rtc_update_irq(ldata->rtc, 1, events);

                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static int pl031_read_time(struct device *dev, struct rtc_time *tm)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);

        rtc_time_to_tm(readl(ldata->base + RTC_DR), tm);

        return 0;
}

static int pl031_set_time(struct device *dev, struct rtc_time *tm)
{
        unsigned long time;
        struct pl031_local *ldata = dev_get_drvdata(dev);
        int ret;

        ret = rtc_tm_to_time(tm, &time);

        if (ret == 0)
                writel(time, ldata->base + RTC_LR);

        return ret;
}

static int pl031_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);

        rtc_time_to_tm(readl(ldata->base + RTC_MR), &alarm->time);

        alarm->pending = readl(ldata->base + RTC_RIS) & RTC_BIT_AI;
        alarm->enabled = readl(ldata->base + RTC_IMSC) & RTC_BIT_AI;

        return 0;
}

static int pl031_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct pl031_local *ldata = dev_get_drvdata(dev);
        unsigned long time;
        int ret;

        /* At the moment, we can only deal with non-wildcarded alarm times. */
        ret = rtc_valid_tm(&alarm->time);
        if (ret == 0) {
                ret = rtc_tm_to_time(&alarm->time, &time);
                if (ret == 0) {
                        writel(time, ldata->base + RTC_MR);
                        pl031_alarm_irq_enable(dev, alarm->enabled);
                }
        }

        return ret;
}

static int pl031_remove(struct amba_device *adev)
{
        struct pl031_local *ldata = dev_get_drvdata(&adev->dev);

        amba_set_drvdata(adev, NULL);
        free_irq(adev->irq[0], ldata->rtc);
        rtc_device_unregister(ldata->rtc);
        iounmap(ldata->base);
        kfree(ldata);
        amba_release_regions(adev);

        return 0;
}

static int pl031_probe(struct amba_device *adev, const struct amba_id *id)
{
        int ret;
        struct pl031_local *ldata;
        struct rtc_class_ops *ops = id->data;

        ret = amba_request_regions(adev, NULL);
        if (ret)
                goto err_req;

        ldata = kzalloc(sizeof(struct pl031_local), GFP_KERNEL);
        if (!ldata) {
                ret = -ENOMEM;
                goto out;
        }

        ldata->base = ioremap(adev->res.start, resource_size(&adev->res));

        if (!ldata->base) {
                ret = -ENOMEM;
                goto out_no_remap;
        }

        amba_set_drvdata(adev, ldata);

        ldata->hw_designer = amba_manf(adev);
        ldata->hw_revision = amba_rev(adev);

        dev_dbg(&adev->dev, "designer ID = 0x%02x\n", ldata->hw_designer);
        dev_dbg(&adev->dev, "revision = 0x%01x\n", ldata->hw_revision);

        /* Enable the clockwatch on ST Variants */
        if ((ldata->hw_designer == AMBA_VENDOR_ST) &&
            (ldata->hw_revision > 1))
                writel(readl(ldata->base + RTC_CR) | RTC_CR_CWEN,
                       ldata->base + RTC_CR);

        ldata->rtc = rtc_device_register("pl031", &adev->dev, ops,
                                        THIS_MODULE);
        if (IS_ERR(ldata->rtc)) {
                ret = PTR_ERR(ldata->rtc);
                goto out_no_rtc;
        }

        if (request_irq(adev->irq[0], pl031_interrupt,
                        IRQF_DISABLED, "rtc-pl031", ldata)) {
                ret = -EIO;
                goto out_no_irq;
        }

        return 0;

out_no_irq:
        rtc_device_unregister(ldata->rtc);
out_no_rtc:
        iounmap(ldata->base);
        amba_set_drvdata(adev, NULL);
out_no_remap:
        kfree(ldata);
out:
        amba_release_regions(adev);
err_req:

        return ret;
}

/* Operations for the original ARM version */
static struct rtc_class_ops arm_pl031_ops = {
        .read_time = pl031_read_time,
        .set_time = pl031_set_time,
        .read_alarm = pl031_read_alarm,
        .set_alarm = pl031_set_alarm,
        .alarm_irq_enable = pl031_alarm_irq_enable,
};

/* The First ST derivative */
static struct rtc_class_ops stv1_pl031_ops = {
        .read_time = pl031_read_time,
        .set_time = pl031_set_time,
        .read_alarm = pl031_read_alarm,
        .set_alarm = pl031_set_alarm,
        .alarm_irq_enable = pl031_alarm_irq_enable,
};

/* And the second ST derivative */
static struct rtc_class_ops stv2_pl031_ops = {
        .read_time = pl031_stv2_read_time,
        .set_time = pl031_stv2_set_time,
        .read_alarm = pl031_stv2_read_alarm,
        .set_alarm = pl031_stv2_set_alarm,
        .alarm_irq_enable = pl031_alarm_irq_enable,
};

static struct amba_id pl031_ids[] = {
        {
                .id = 0x00041031,
                .mask = 0x000fffff,
                .data = &arm_pl031_ops,
        },
        /* ST Micro variants */
        {
                .id = 0x00180031,
                .mask = 0x00ffffff,
                .data = &stv1_pl031_ops,
        },
        {
                .id = 0x00280031,
                .mask = 0x00ffffff,
                .data = &stv2_pl031_ops,
        },
        {0, 0},
};

MODULE_DEVICE_TABLE(amba, pl031_ids);

static struct amba_driver pl031_driver = {
        .drv = {
                .name = "rtc-pl031",
        },
        .id_table = pl031_ids,
        .probe = pl031_probe,
        .remove = pl031_remove,
};

static int __init pl031_init(void)
{
        return amba_driver_register(&pl031_driver);
}

static void __exit pl031_exit(void)
{
        amba_driver_unregister(&pl031_driver);
}

module_init(pl031_init);
module_exit(pl031_exit);

MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net");
MODULE_DESCRIPTION("ARM AMBA PL031 RTC Driver");
MODULE_LICENSE("GPL");