rtc-vt8500.c

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/*
 * drivers/rtc/rtc-vt8500.c
 *
 *  Copyright (C) 2010 Alexey Charkov <[email protected]>
 *
 * Based on rtc-pxa.c
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/of.h>

/*
 * Register definitions
 */
#define VT8500_RTC_TS       0x00    /* Time set */
#define VT8500_RTC_DS       0x04    /* Date set */
#define VT8500_RTC_AS       0x08    /* Alarm set */
#define VT8500_RTC_CR       0x0c    /* Control */
#define VT8500_RTC_TR       0x10    /* Time read */
#define VT8500_RTC_DR       0x14    /* Date read */
#define VT8500_RTC_WS       0x18    /* Write status */
#define VT8500_RTC_CL       0x20    /* Calibration */
#define VT8500_RTC_IS       0x24    /* Interrupt status */
#define VT8500_RTC_ST       0x28    /* Status */

#define INVALID_TIME_BIT    (1 << 31)

#define DATE_CENTURY_S      19
#define DATE_YEAR_S     11
#define DATE_YEAR_MASK      (0xff << DATE_YEAR_S)
#define DATE_MONTH_S        6
#define DATE_MONTH_MASK     (0x1f << DATE_MONTH_S)
#define DATE_DAY_MASK       0x3f

#define TIME_DOW_S      20
#define TIME_DOW_MASK       (0x07 << TIME_DOW_S)
#define TIME_HOUR_S     14
#define TIME_HOUR_MASK      (0x3f << TIME_HOUR_S)
#define TIME_MIN_S      7
#define TIME_MIN_MASK       (0x7f << TIME_MIN_S)
#define TIME_SEC_MASK       0x7f

#define ALARM_DAY_S     20
#define ALARM_DAY_MASK      (0x3f << ALARM_DAY_S)

#define ALARM_DAY_BIT       (1 << 29)
#define ALARM_HOUR_BIT      (1 << 28)
#define ALARM_MIN_BIT       (1 << 27)
#define ALARM_SEC_BIT       (1 << 26)

#define ALARM_ENABLE_MASK   (ALARM_DAY_BIT \
                | ALARM_HOUR_BIT \
                | ALARM_MIN_BIT \
                | ALARM_SEC_BIT)

#define VT8500_RTC_CR_ENABLE    (1 << 0)    /* Enable RTC */
#define VT8500_RTC_CR_24H   (1 << 1)    /* 24h time format */
#define VT8500_RTC_CR_SM_ENABLE (1 << 2)    /* Enable periodic irqs */
#define VT8500_RTC_CR_SM_SEC    (1 << 3)    /* 0: 1Hz/60, 1: 1Hz */
#define VT8500_RTC_CR_CALIB (1 << 4)    /* Enable calibration */

#define VT8500_RTC_IS_ALARM (1 << 0)    /* Alarm interrupt status */

struct vt8500_rtc {
    void __iomem        *regbase;
    struct resource     *res;
    int         irq_alarm;
    struct rtc_device   *rtc;
    spinlock_t      lock;       /* Protects this structure */
};

static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
{
    struct vt8500_rtc *vt8500_rtc = dev_id;
    u32 isr;
    unsigned long events = 0;

    spin_lock(&vt8500_rtc->lock);

    /* clear interrupt sources */
    isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
    writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);

    spin_unlock(&vt8500_rtc->lock);

    if (isr & VT8500_RTC_IS_ALARM)
        events |= RTC_AF | RTC_IRQF;

    rtc_update_irq(vt8500_rtc->rtc, 1, events);

    return IRQ_HANDLED;
}

static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
    u32 date, time;

    date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
    time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);

    tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
    tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
    tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
    tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
    tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S);
    tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S)
            + ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
    tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;

    return 0;
}

static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

    if (tm->tm_year < 100) {
        dev_warn(dev, "Only years 2000-2199 are supported by the "
                  "hardware!\n");
        return -EINVAL;
    }

    writel((bin2bcd(tm->tm_year - 100) << DATE_YEAR_S)
        | (bin2bcd(tm->tm_mon) << DATE_MONTH_S)
        | (bin2bcd(tm->tm_mday)),
        vt8500_rtc->regbase + VT8500_RTC_DS);
    writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
        | (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
        | (bin2bcd(tm->tm_min) << TIME_MIN_S)
        | (bin2bcd(tm->tm_sec)),
        vt8500_rtc->regbase + VT8500_RTC_TS);

    return 0;
}

static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
    u32 isr, alarm;

    alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
    isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);

    alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
    alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
    alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
    alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));

    alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
    alrm->pending = (isr & VT8500_RTC_IS_ALARM) ? 1 : 0;

    return rtc_valid_tm(&alrm->time);
}

static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

    writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
        | (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
        | (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
        | (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
        | (bin2bcd(alrm->time.tm_sec)),
        vt8500_rtc->regbase + VT8500_RTC_AS);

    return 0;
}

static int vt8500_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
    unsigned long tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);

    if (enabled)
        tmp |= ALARM_ENABLE_MASK;
    else
        tmp &= ~ALARM_ENABLE_MASK;

    writel(tmp, vt8500_rtc->regbase + VT8500_RTC_AS);
    return 0;
}

static const struct rtc_class_ops vt8500_rtc_ops = {
    .read_time = vt8500_rtc_read_time,
    .set_time = vt8500_rtc_set_time,
    .read_alarm = vt8500_rtc_read_alarm,
    .set_alarm = vt8500_rtc_set_alarm,
    .alarm_irq_enable = vt8500_alarm_irq_enable,
};

static int __devinit vt8500_rtc_probe(struct platform_device *pdev)
{
    struct vt8500_rtc *vt8500_rtc;
    int ret;

    vt8500_rtc = kzalloc(sizeof(struct vt8500_rtc), GFP_KERNEL);
    if (!vt8500_rtc)
        return -ENOMEM;

    spin_lock_init(&vt8500_rtc->lock);
    platform_set_drvdata(pdev, vt8500_rtc);

    vt8500_rtc->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!vt8500_rtc->res) {
        dev_err(&pdev->dev, "No I/O memory resource defined\n");
        ret = -ENXIO;
        goto err_free;
    }

    vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
    if (vt8500_rtc->irq_alarm < 0) {
        dev_err(&pdev->dev, "No alarm IRQ resource defined\n");
        ret = -ENXIO;
        goto err_free;
    }

    vt8500_rtc->res = request_mem_region(vt8500_rtc->res->start,
                         resource_size(vt8500_rtc->res),
                         "vt8500-rtc");
    if (vt8500_rtc->res == NULL) {
        dev_err(&pdev->dev, "failed to request I/O memory\n");
        ret = -EBUSY;
        goto err_free;
    }

    vt8500_rtc->regbase = ioremap(vt8500_rtc->res->start,
                      resource_size(vt8500_rtc->res));
    if (!vt8500_rtc->regbase) {
        dev_err(&pdev->dev, "Unable to map RTC I/O memory\n");
        ret = -EBUSY;
        goto err_release;
    }

    /* Enable RTC and set it to 24-hour mode */
    writel(VT8500_RTC_CR_ENABLE | VT8500_RTC_CR_24H,
           vt8500_rtc->regbase + VT8500_RTC_CR);

    vt8500_rtc->rtc = rtc_device_register("vt8500-rtc", &pdev->dev,
                          &vt8500_rtc_ops, THIS_MODULE);
    if (IS_ERR(vt8500_rtc->rtc)) {
        ret = PTR_ERR(vt8500_rtc->rtc);
        dev_err(&pdev->dev,
            "Failed to register RTC device -> %d\n", ret);
        goto err_unmap;
    }

    ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, 0,
              "rtc alarm", vt8500_rtc);
    if (ret < 0) {
        dev_err(&pdev->dev, "can't get irq %i, err %d\n",
            vt8500_rtc->irq_alarm, ret);
        goto err_unreg;
    }

    return 0;

err_unreg:
    rtc_device_unregister(vt8500_rtc->rtc);
err_unmap:
    iounmap(vt8500_rtc->regbase);
err_release:
    release_mem_region(vt8500_rtc->res->start,
               resource_size(vt8500_rtc->res));
err_free:
    kfree(vt8500_rtc);
    return ret;
}

static int __devexit vt8500_rtc_remove(struct platform_device *pdev)
{
    struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);

    free_irq(vt8500_rtc->irq_alarm, vt8500_rtc);

    rtc_device_unregister(vt8500_rtc->rtc);

    /* Disable alarm matching */
    writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
    iounmap(vt8500_rtc->regbase);
    release_mem_region(vt8500_rtc->res->start,
               resource_size(vt8500_rtc->res));

    kfree(vt8500_rtc);
    platform_set_drvdata(pdev, NULL);

    return 0;
}

static const struct of_device_id wmt_dt_ids[] = {
    { .compatible = "via,vt8500-rtc", },
    {}
};

static struct platform_driver vt8500_rtc_driver = {
    .probe      = vt8500_rtc_probe,
    .remove     = __devexit_p(vt8500_rtc_remove),
    .driver     = {
        .name   = "vt8500-rtc",
        .owner  = THIS_MODULE,
        .of_match_table = of_match_ptr(wmt_dt_ids),
    },
};

module_platform_driver(vt8500_rtc_driver);

MODULE_AUTHOR("Alexey Charkov <[email protected]>");
MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:vt8500-rtc");