rtc-ds1511.c

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/*
 * An rtc driver for the Dallas DS1511
 *
 * Copyright (C) 2006 Atsushi Nemoto <[email protected]>
 * Copyright (C) 2007 Andrew Sharp <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Real time clock driver for the Dallas 1511 chip, which also
 * contains a watchdog timer.  There is a tiny amount of code that
 * platform code could use to mess with the watchdog device a little
 * bit, but not a full watchdog driver.
 */

#include <linux/bcd.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/module.h>

#define DRV_VERSION "0.6"

enum ds1511reg {
    DS1511_SEC = 0x0,
    DS1511_MIN = 0x1,
    DS1511_HOUR = 0x2,
    DS1511_DOW = 0x3,
    DS1511_DOM = 0x4,
    DS1511_MONTH = 0x5,
    DS1511_YEAR = 0x6,
    DS1511_CENTURY = 0x7,
    DS1511_AM1_SEC = 0x8,
    DS1511_AM2_MIN = 0x9,
    DS1511_AM3_HOUR = 0xa,
    DS1511_AM4_DATE = 0xb,
    DS1511_WD_MSEC = 0xc,
    DS1511_WD_SEC = 0xd,
    DS1511_CONTROL_A = 0xe,
    DS1511_CONTROL_B = 0xf,
    DS1511_RAMADDR_LSB = 0x10,
    DS1511_RAMDATA = 0x13
};

#define DS1511_BLF1 0x80
#define DS1511_BLF2 0x40
#define DS1511_PRS  0x20
#define DS1511_PAB  0x10
#define DS1511_TDF  0x08
#define DS1511_KSF  0x04
#define DS1511_WDF  0x02
#define DS1511_IRQF 0x01
#define DS1511_TE   0x80
#define DS1511_CS   0x40
#define DS1511_BME  0x20
#define DS1511_TPE  0x10
#define DS1511_TIE  0x08
#define DS1511_KIE  0x04
#define DS1511_WDE  0x02
#define DS1511_WDS  0x01
#define DS1511_RAM_MAX  0xff

#define RTC_CMD     DS1511_CONTROL_B
#define RTC_CMD1    DS1511_CONTROL_A

#define RTC_ALARM_SEC   DS1511_AM1_SEC
#define RTC_ALARM_MIN   DS1511_AM2_MIN
#define RTC_ALARM_HOUR  DS1511_AM3_HOUR
#define RTC_ALARM_DATE  DS1511_AM4_DATE

#define RTC_SEC     DS1511_SEC
#define RTC_MIN     DS1511_MIN
#define RTC_HOUR    DS1511_HOUR
#define RTC_DOW     DS1511_DOW
#define RTC_DOM     DS1511_DOM
#define RTC_MON     DS1511_MONTH
#define RTC_YEAR    DS1511_YEAR
#define RTC_CENTURY DS1511_CENTURY

#define RTC_TIE DS1511_TIE
#define RTC_TE  DS1511_TE

struct rtc_plat_data {
    struct rtc_device *rtc;
    void __iomem *ioaddr;       /* virtual base address */
    int size;               /* amount of memory mapped */
    int irq;
    unsigned int irqen;
    int alrm_sec;
    int alrm_min;
    int alrm_hour;
    int alrm_mday;
    spinlock_t lock;
};

static DEFINE_SPINLOCK(ds1511_lock);

static __iomem char *ds1511_base;
static u32 reg_spacing = 1;

 static noinline void
rtc_write(uint8_t val, uint32_t reg)
{
    writeb(val, ds1511_base + (reg * reg_spacing));
}

 static inline void
rtc_write_alarm(uint8_t val, enum ds1511reg reg)
{
    rtc_write((val | 0x80), reg);
}

 static noinline uint8_t
rtc_read(enum ds1511reg reg)
{
    return readb(ds1511_base + (reg * reg_spacing));
}

 static inline void
rtc_disable_update(void)
{
    rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
}

 static void
rtc_enable_update(void)
{
    rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
}

/*
 * #define DS1511_WDOG_RESET_SUPPORT
 *
 * Uncomment this if you want to use these routines in
 * some platform code.
 */
#ifdef DS1511_WDOG_RESET_SUPPORT
/*
 * just enough code to set the watchdog timer so that it
 * will reboot the system
 */
 void
ds1511_wdog_set(unsigned long deciseconds)
{
    /*
     * the wdog timer can take 99.99 seconds
     */
    deciseconds %= 10000;
    /*
     * set the wdog values in the wdog registers
     */
    rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
    rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
    /*
     * set wdog enable and wdog 'steering' bit to issue a reset
     */
    rtc_write(DS1511_WDE | DS1511_WDS, RTC_CMD);
}

 void
ds1511_wdog_disable(void)
{
    /*
     * clear wdog enable and wdog 'steering' bits
     */
    rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
    /*
     * clear the wdog counter
     */
    rtc_write(0, DS1511_WD_MSEC);
    rtc_write(0, DS1511_WD_SEC);
}
#endif

/*
 * set the rtc chip's idea of the time.
 * stupidly, some callers call with year unmolested;
 * and some call with  year = year - 1900.  thanks.
 */
static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
{
    u8 mon, day, dow, hrs, min, sec, yrs, cen;
    unsigned long flags;

    /*
     * won't have to change this for a while
     */
    if (rtc_tm->tm_year < 1900) {
        rtc_tm->tm_year += 1900;
    }

    if (rtc_tm->tm_year < 1970) {
        return -EINVAL;
    }
    yrs = rtc_tm->tm_year % 100;
    cen = rtc_tm->tm_year / 100;
    mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
    day = rtc_tm->tm_mday;
    dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
    hrs = rtc_tm->tm_hour;
    min = rtc_tm->tm_min;
    sec = rtc_tm->tm_sec;

    if ((mon > 12) || (day == 0)) {
        return -EINVAL;
    }

    if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year)) {
        return -EINVAL;
    }

    if ((hrs >= 24) || (min >= 60) || (sec >= 60)) {
        return -EINVAL;
    }

    /*
     * each register is a different number of valid bits
     */
    sec = bin2bcd(sec) & 0x7f;
    min = bin2bcd(min) & 0x7f;
    hrs = bin2bcd(hrs) & 0x3f;
    day = bin2bcd(day) & 0x3f;
    mon = bin2bcd(mon) & 0x1f;
    yrs = bin2bcd(yrs) & 0xff;
    cen = bin2bcd(cen) & 0xff;

    spin_lock_irqsave(&ds1511_lock, flags);
    rtc_disable_update();
    rtc_write(cen, RTC_CENTURY);
    rtc_write(yrs, RTC_YEAR);
    rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
    rtc_write(day, RTC_DOM);
    rtc_write(hrs, RTC_HOUR);
    rtc_write(min, RTC_MIN);
    rtc_write(sec, RTC_SEC);
    rtc_write(dow, RTC_DOW);
    rtc_enable_update();
    spin_unlock_irqrestore(&ds1511_lock, flags);

    return 0;
}

static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
{
    unsigned int century;
    unsigned long flags;

    spin_lock_irqsave(&ds1511_lock, flags);
    rtc_disable_update();

    rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
    rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
    rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
    rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
    rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
    rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
    rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
    century = rtc_read(RTC_CENTURY);

    rtc_enable_update();
    spin_unlock_irqrestore(&ds1511_lock, flags);

    rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
    rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
    rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
    rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
    rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
    rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
    rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
    century = bcd2bin(century) * 100;

    /*
     * Account for differences between how the RTC uses the values
     * and how they are defined in a struct rtc_time;
     */
    century += rtc_tm->tm_year;
    rtc_tm->tm_year = century - 1900;

    rtc_tm->tm_mon--;

    if (rtc_valid_tm(rtc_tm) < 0) {
        dev_err(dev, "retrieved date/time is not valid.\n");
        rtc_time_to_tm(0, rtc_tm);
    }
    return 0;
}

/*
 * write the alarm register settings
 *
 * we only have the use to interrupt every second, otherwise
 * known as the update interrupt, or the interrupt if the whole
 * date/hours/mins/secs matches.  the ds1511 has many more
 * permutations, but the kernel doesn't.
 */
 static void
ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
{
    unsigned long flags;

    spin_lock_irqsave(&pdata->lock, flags);
    rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
           RTC_ALARM_DATE);
    rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
           RTC_ALARM_HOUR);
    rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
           RTC_ALARM_MIN);
    rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
           RTC_ALARM_SEC);
    rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
    rtc_read(RTC_CMD1); /* clear interrupts */
    spin_unlock_irqrestore(&pdata->lock, flags);
}

 static int
ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

    if (pdata->irq <= 0)
        return -EINVAL;

    pdata->alrm_mday = alrm->time.tm_mday;
    pdata->alrm_hour = alrm->time.tm_hour;
    pdata->alrm_min = alrm->time.tm_min;
    pdata->alrm_sec = alrm->time.tm_sec;
    if (alrm->enabled) {
        pdata->irqen |= RTC_AF;
    }
    ds1511_rtc_update_alarm(pdata);
    return 0;
}

 static int
ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

    if (pdata->irq <= 0)
        return -EINVAL;

    alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
    alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
    alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
    alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
    alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
    return 0;
}

 static irqreturn_t
ds1511_interrupt(int irq, void *dev_id)
{
    struct platform_device *pdev = dev_id;
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
    unsigned long events = 0;

    spin_lock(&pdata->lock);
    /*
     * read and clear interrupt
     */
    if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
        events = RTC_IRQF;
        if (rtc_read(RTC_ALARM_SEC) & 0x80)
            events |= RTC_UF;
        else
            events |= RTC_AF;
        if (likely(pdata->rtc))
            rtc_update_irq(pdata->rtc, 1, events);
    }
    spin_unlock(&pdata->lock);
    return events ? IRQ_HANDLED : IRQ_NONE;
}

static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

    if (pdata->irq <= 0)
        return -EINVAL;
    if (enabled)
        pdata->irqen |= RTC_AF;
    else
        pdata->irqen &= ~RTC_AF;
    ds1511_rtc_update_alarm(pdata);
    return 0;
}

static const struct rtc_class_ops ds1511_rtc_ops = {
    .read_time      = ds1511_rtc_read_time,
    .set_time       = ds1511_rtc_set_time,
    .read_alarm     = ds1511_rtc_read_alarm,
    .set_alarm      = ds1511_rtc_set_alarm,
    .alarm_irq_enable   = ds1511_rtc_alarm_irq_enable,
};

 static ssize_t
ds1511_nvram_read(struct file *filp, struct kobject *kobj,
          struct bin_attribute *ba,
          char *buf, loff_t pos, size_t size)
{
    ssize_t count;

    /*
     * if count is more than one, turn on "burst" mode
     * turn it off when you're done
     */
    if (size > 1) {
        rtc_write((rtc_read(RTC_CMD) | DS1511_BME), RTC_CMD);
    }
    if (pos > DS1511_RAM_MAX) {
        pos = DS1511_RAM_MAX;
    }
    if (size + pos > DS1511_RAM_MAX + 1) {
        size = DS1511_RAM_MAX - pos + 1;
    }
    rtc_write(pos, DS1511_RAMADDR_LSB);
    for (count = 0; size > 0; count++, size--) {
        *buf++ = rtc_read(DS1511_RAMDATA);
    }
    if (count > 1) {
        rtc_write((rtc_read(RTC_CMD) & ~DS1511_BME), RTC_CMD);
    }
    return count;
}

 static ssize_t
ds1511_nvram_write(struct file *filp, struct kobject *kobj,
           struct bin_attribute *bin_attr,
           char *buf, loff_t pos, size_t size)
{
    ssize_t count;

    /*
     * if count is more than one, turn on "burst" mode
     * turn it off when you're done
     */
    if (size > 1) {
        rtc_write((rtc_read(RTC_CMD) | DS1511_BME), RTC_CMD);
    }
    if (pos > DS1511_RAM_MAX) {
        pos = DS1511_RAM_MAX;
    }
    if (size + pos > DS1511_RAM_MAX + 1) {
        size = DS1511_RAM_MAX - pos + 1;
    }
    rtc_write(pos, DS1511_RAMADDR_LSB);
    for (count = 0; size > 0; count++, size--) {
        rtc_write(*buf++, DS1511_RAMDATA);
    }
    if (count > 1) {
        rtc_write((rtc_read(RTC_CMD) & ~DS1511_BME), RTC_CMD);
    }
    return count;
}

static struct bin_attribute ds1511_nvram_attr = {
    .attr = {
        .name = "nvram",
        .mode = S_IRUGO | S_IWUSR,
    },
    .size = DS1511_RAM_MAX,
    .read = ds1511_nvram_read,
    .write = ds1511_nvram_write,
};

 static int __devinit
ds1511_rtc_probe(struct platform_device *pdev)
{
    struct rtc_device *rtc;
    struct resource *res;
    struct rtc_plat_data *pdata;
    int ret = 0;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res) {
        return -ENODEV;
    }
    pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
    if (!pdata)
        return -ENOMEM;
    pdata->size = resource_size(res);
    if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
            pdev->name))
        return -EBUSY;
    ds1511_base = devm_ioremap(&pdev->dev, res->start, pdata->size);
    if (!ds1511_base)
        return -ENOMEM;
    pdata->ioaddr = ds1511_base;
    pdata->irq = platform_get_irq(pdev, 0);

    /*
     * turn on the clock and the crystal, etc.
     */
    rtc_write(0, RTC_CMD);
    rtc_write(0, RTC_CMD1);
    /*
     * clear the wdog counter
     */
    rtc_write(0, DS1511_WD_MSEC);
    rtc_write(0, DS1511_WD_SEC);
    /*
     * start the clock
     */
    rtc_enable_update();

    /*
     * check for a dying bat-tree
     */
    if (rtc_read(RTC_CMD1) & DS1511_BLF1) {
        dev_warn(&pdev->dev, "voltage-low detected.\n");
    }

    spin_lock_init(&pdata->lock);
    platform_set_drvdata(pdev, pdata);
    /*
     * if the platform has an interrupt in mind for this device,
     * then by all means, set it
     */
    if (pdata->irq > 0) {
        rtc_read(RTC_CMD1);
        if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
            IRQF_SHARED, pdev->name, pdev) < 0) {

            dev_warn(&pdev->dev, "interrupt not available.\n");
            pdata->irq = 0;
        }
    }

    rtc = rtc_device_register(pdev->name, &pdev->dev, &ds1511_rtc_ops,
        THIS_MODULE);
    if (IS_ERR(rtc))
        return PTR_ERR(rtc);
    pdata->rtc = rtc;

    ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
    if (ret)
        rtc_device_unregister(pdata->rtc);
    return ret;
}

 static int __devexit
ds1511_rtc_remove(struct platform_device *pdev)
{
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

    sysfs_remove_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
    rtc_device_unregister(pdata->rtc);
    if (pdata->irq > 0) {
        /*
         * disable the alarm interrupt
         */
        rtc_write(rtc_read(RTC_CMD) & ~RTC_TIE, RTC_CMD);
        rtc_read(RTC_CMD1);
    }
    return 0;
}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:ds1511");

static struct platform_driver ds1511_rtc_driver = {
    .probe      = ds1511_rtc_probe,
    .remove     = __devexit_p(ds1511_rtc_remove),
    .driver     = {
        .name   = "ds1511",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(ds1511_rtc_driver);

MODULE_AUTHOR("Andrew Sharp <[email protected]>");
MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);