rtc-ds1286.c

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/*
 * DS1286 Real Time Clock interface for Linux
 *
 * Copyright (C) 1998, 1999, 2000 Ralf Baechle
 * Copyright (C) 2008 Thomas Bogendoerfer
 *
 * Based on code written by Paul Gortmaker.
 *
 * 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/platform_device.h>
#include <linux/bcd.h>
#include <linux/ds1286.h>
#include <linux/io.h>
#include <linux/slab.h>

#define DRV_VERSION     "1.0"

struct ds1286_priv {
    struct rtc_device *rtc;
    u32 __iomem *rtcregs;
    size_t size;
    unsigned long baseaddr;
    spinlock_t lock;
};

static inline u8 ds1286_rtc_read(struct ds1286_priv *priv, int reg)
{
    return __raw_readl(&priv->rtcregs[reg]) & 0xff;
}

static inline void ds1286_rtc_write(struct ds1286_priv *priv, u8 data, int reg)
{
    __raw_writel(data, &priv->rtcregs[reg]);
}


static int ds1286_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned long flags;
    unsigned char val;

    /* Allow or mask alarm interrupts */
    spin_lock_irqsave(&priv->lock, flags);
    val = ds1286_rtc_read(priv, RTC_CMD);
    if (enabled)
        val &=  ~RTC_TDM;
    else
        val |=  RTC_TDM;
    ds1286_rtc_write(priv, val, RTC_CMD);
    spin_unlock_irqrestore(&priv->lock, flags);

    return 0;
}

#ifdef CONFIG_RTC_INTF_DEV

static int ds1286_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned long flags;
    unsigned char val;

    switch (cmd) {
    case RTC_WIE_OFF:
        /* Mask watchdog int. enab. bit */
        spin_lock_irqsave(&priv->lock, flags);
        val = ds1286_rtc_read(priv, RTC_CMD);
        val |= RTC_WAM;
        ds1286_rtc_write(priv, val, RTC_CMD);
        spin_unlock_irqrestore(&priv->lock, flags);
        break;
    case RTC_WIE_ON:
        /* Allow watchdog interrupts.   */
        spin_lock_irqsave(&priv->lock, flags);
        val = ds1286_rtc_read(priv, RTC_CMD);
        val &= ~RTC_WAM;
        ds1286_rtc_write(priv, val, RTC_CMD);
        spin_unlock_irqrestore(&priv->lock, flags);
        break;
    default:
        return -ENOIOCTLCMD;
    }
    return 0;
}

#else
#define ds1286_ioctl    NULL
#endif

#ifdef CONFIG_PROC_FS

static int ds1286_proc(struct device *dev, struct seq_file *seq)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned char month, cmd, amode;
    const char *s;

    month = ds1286_rtc_read(priv, RTC_MONTH);
    seq_printf(seq,
           "oscillator\t: %s\n"
           "square_wave\t: %s\n",
           (month & RTC_EOSC) ? "disabled" : "enabled",
           (month & RTC_ESQW) ? "disabled" : "enabled");

    amode = ((ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x80) >> 5) |
        ((ds1286_rtc_read(priv, RTC_HOURS_ALARM) & 0x80) >> 6) |
        ((ds1286_rtc_read(priv, RTC_DAY_ALARM) & 0x80) >> 7);
    switch (amode) {
    case 7:
        s = "each minute";
        break;
    case 3:
        s = "minutes match";
        break;
    case 1:
        s = "hours and minutes match";
        break;
    case 0:
        s = "days, hours and minutes match";
        break;
    default:
        s = "invalid";
        break;
    }
    seq_printf(seq, "alarm_mode\t: %s\n", s);

    cmd = ds1286_rtc_read(priv, RTC_CMD);
    seq_printf(seq,
           "alarm_enable\t: %s\n"
           "wdog_alarm\t: %s\n"
           "alarm_mask\t: %s\n"
           "wdog_alarm_mask\t: %s\n"
           "interrupt_mode\t: %s\n"
           "INTB_mode\t: %s_active\n"
           "interrupt_pins\t: %s\n",
           (cmd & RTC_TDF) ? "yes" : "no",
           (cmd & RTC_WAF) ? "yes" : "no",
           (cmd & RTC_TDM) ? "disabled" : "enabled",
           (cmd & RTC_WAM) ? "disabled" : "enabled",
           (cmd & RTC_PU_LVL) ? "pulse" : "level",
           (cmd & RTC_IBH_LO) ? "low" : "high",
           (cmd & RTC_IPSW) ? "unswapped" : "swapped");
    return 0;
}

#else
#define ds1286_proc     NULL
#endif

static int ds1286_read_time(struct device *dev, struct rtc_time *tm)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned char save_control;
    unsigned long flags;
    unsigned long uip_watchdog = jiffies;

    /*
     * read RTC once any update in progress is done. The update
     * can take just over 2ms. We wait 10 to 20ms. There is no need to
     * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
     * If you need to know *exactly* when a second has started, enable
     * periodic update complete interrupts, (via ioctl) and then
     * immediately read /dev/rtc which will block until you get the IRQ.
     * Once the read clears, read the RTC time (again via ioctl). Easy.
     */

    if (ds1286_rtc_read(priv, RTC_CMD) & RTC_TE)
        while (time_before(jiffies, uip_watchdog + 2*HZ/100))
            barrier();

    /*
     * Only the values that we read from the RTC are set. We leave
     * tm_wday, tm_yday and tm_isdst untouched. Even though the
     * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
     * by the RTC when initially set to a non-zero value.
     */
    spin_lock_irqsave(&priv->lock, flags);
    save_control = ds1286_rtc_read(priv, RTC_CMD);
    ds1286_rtc_write(priv, (save_control|RTC_TE), RTC_CMD);

    tm->tm_sec = ds1286_rtc_read(priv, RTC_SECONDS);
    tm->tm_min = ds1286_rtc_read(priv, RTC_MINUTES);
    tm->tm_hour = ds1286_rtc_read(priv, RTC_HOURS) & 0x3f;
    tm->tm_mday = ds1286_rtc_read(priv, RTC_DATE);
    tm->tm_mon = ds1286_rtc_read(priv, RTC_MONTH) & 0x1f;
    tm->tm_year = ds1286_rtc_read(priv, RTC_YEAR);

    ds1286_rtc_write(priv, save_control, RTC_CMD);
    spin_unlock_irqrestore(&priv->lock, flags);

    tm->tm_sec = bcd2bin(tm->tm_sec);
    tm->tm_min = bcd2bin(tm->tm_min);
    tm->tm_hour = bcd2bin(tm->tm_hour);
    tm->tm_mday = bcd2bin(tm->tm_mday);
    tm->tm_mon = bcd2bin(tm->tm_mon);
    tm->tm_year = bcd2bin(tm->tm_year);

    /*
     * Account for differences between how the RTC uses the values
     * and how they are defined in a struct rtc_time;
     */
    if (tm->tm_year < 45)
        tm->tm_year += 30;
    tm->tm_year += 40;
    if (tm->tm_year < 70)
        tm->tm_year += 100;

    tm->tm_mon--;

    return rtc_valid_tm(tm);
}

static int ds1286_set_time(struct device *dev, struct rtc_time *tm)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned char mon, day, hrs, min, sec;
    unsigned char save_control;
    unsigned int yrs;
    unsigned long flags;

    yrs = tm->tm_year + 1900;
    mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
    day = tm->tm_mday;
    hrs = tm->tm_hour;
    min = tm->tm_min;
    sec = tm->tm_sec;

    if (yrs < 1970)
        return -EINVAL;

    yrs -= 1940;
    if (yrs > 255)    /* They are unsigned */
        return -EINVAL;

    if (yrs >= 100)
        yrs -= 100;

    sec = bin2bcd(sec);
    min = bin2bcd(min);
    hrs = bin2bcd(hrs);
    day = bin2bcd(day);
    mon = bin2bcd(mon);
    yrs = bin2bcd(yrs);

    spin_lock_irqsave(&priv->lock, flags);
    save_control = ds1286_rtc_read(priv, RTC_CMD);
    ds1286_rtc_write(priv, (save_control|RTC_TE), RTC_CMD);

    ds1286_rtc_write(priv, yrs, RTC_YEAR);
    ds1286_rtc_write(priv, mon, RTC_MONTH);
    ds1286_rtc_write(priv, day, RTC_DATE);
    ds1286_rtc_write(priv, hrs, RTC_HOURS);
    ds1286_rtc_write(priv, min, RTC_MINUTES);
    ds1286_rtc_write(priv, sec, RTC_SECONDS);
    ds1286_rtc_write(priv, 0, RTC_HUNDREDTH_SECOND);

    ds1286_rtc_write(priv, save_control, RTC_CMD);
    spin_unlock_irqrestore(&priv->lock, flags);
    return 0;
}

static int ds1286_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned char cmd;
    unsigned long flags;

    /*
     * Only the values that we read from the RTC are set. That
     * means only tm_wday, tm_hour, tm_min.
     */
    spin_lock_irqsave(&priv->lock, flags);
    alm->time.tm_min = ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x7f;
    alm->time.tm_hour = ds1286_rtc_read(priv, RTC_HOURS_ALARM)  & 0x1f;
    alm->time.tm_wday = ds1286_rtc_read(priv, RTC_DAY_ALARM)    & 0x07;
    cmd = ds1286_rtc_read(priv, RTC_CMD);
    spin_unlock_irqrestore(&priv->lock, flags);

    alm->time.tm_min = bcd2bin(alm->time.tm_min);
    alm->time.tm_hour = bcd2bin(alm->time.tm_hour);
    alm->time.tm_sec = 0;
    return 0;
}

static int ds1286_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    struct ds1286_priv *priv = dev_get_drvdata(dev);
    unsigned char hrs, min, sec;

    hrs = alm->time.tm_hour;
    min = alm->time.tm_min;
    sec = alm->time.tm_sec;

    if (hrs >= 24)
        hrs = 0xff;

    if (min >= 60)
        min = 0xff;

    if (sec != 0)
        return -EINVAL;

    min = bin2bcd(min);
    hrs = bin2bcd(hrs);

    spin_lock(&priv->lock);
    ds1286_rtc_write(priv, hrs, RTC_HOURS_ALARM);
    ds1286_rtc_write(priv, min, RTC_MINUTES_ALARM);
    spin_unlock(&priv->lock);

    return 0;
}

static const struct rtc_class_ops ds1286_ops = {
    .ioctl      = ds1286_ioctl,
    .proc       = ds1286_proc,
    .read_time  = ds1286_read_time,
    .set_time   = ds1286_set_time,
    .read_alarm = ds1286_read_alarm,
    .set_alarm  = ds1286_set_alarm,
    .alarm_irq_enable = ds1286_alarm_irq_enable,
};

static int __devinit ds1286_probe(struct platform_device *pdev)
{
    struct rtc_device *rtc;
    struct resource *res;
    struct ds1286_priv *priv;
    int ret = 0;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res)
        return -ENODEV;
    priv = kzalloc(sizeof(struct ds1286_priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    priv->size = resource_size(res);
    if (!request_mem_region(res->start, priv->size, pdev->name)) {
        ret = -EBUSY;
        goto out;
    }
    priv->baseaddr = res->start;
    priv->rtcregs = ioremap(priv->baseaddr, priv->size);
    if (!priv->rtcregs) {
        ret = -ENOMEM;
        goto out;
    }
    spin_lock_init(&priv->lock);
    platform_set_drvdata(pdev, priv);
    rtc = rtc_device_register("ds1286", &pdev->dev,
                  &ds1286_ops, THIS_MODULE);
    if (IS_ERR(rtc)) {
        ret = PTR_ERR(rtc);
        goto out;
    }
    priv->rtc = rtc;
    return 0;

out:
    if (priv->rtc)
        rtc_device_unregister(priv->rtc);
    if (priv->rtcregs)
        iounmap(priv->rtcregs);
    if (priv->baseaddr)
        release_mem_region(priv->baseaddr, priv->size);
    kfree(priv);
    return ret;
}

static int __devexit ds1286_remove(struct platform_device *pdev)
{
    struct ds1286_priv *priv = platform_get_drvdata(pdev);

    rtc_device_unregister(priv->rtc);
    iounmap(priv->rtcregs);
    release_mem_region(priv->baseaddr, priv->size);
    kfree(priv);
    return 0;
}

static struct platform_driver ds1286_platform_driver = {
    .driver     = {
        .name   = "rtc-ds1286",
        .owner  = THIS_MODULE,
    },
    .probe      = ds1286_probe,
    .remove     = __devexit_p(ds1286_remove),
};

module_platform_driver(ds1286_platform_driver);

MODULE_AUTHOR("Thomas Bogendoerfer <[email protected]>");
MODULE_DESCRIPTION("DS1286 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:rtc-ds1286");