rtc-ab8500.c

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/*
 * Copyright (C) ST-Ericsson SA 2010
 *
 * License terms: GNU General Public License (GPL) version 2
 * Author: Virupax Sadashivpetimath <[email protected]>
 *
 * RTC clock driver for the RTC part of the AB8500 Power management chip.
 * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
 * Linus Walleij <[email protected]>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/mfd/abx500.h>
#include <linux/mfd/abx500/ab8500.h>
#include <linux/delay.h>
#include <linux/of.h>

#define AB8500_RTC_SOFF_STAT_REG    0x00
#define AB8500_RTC_CC_CONF_REG      0x01
#define AB8500_RTC_READ_REQ_REG     0x02
#define AB8500_RTC_WATCH_TSECMID_REG    0x03
#define AB8500_RTC_WATCH_TSECHI_REG 0x04
#define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
#define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
#define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
#define AB8500_RTC_ALRM_MIN_LOW_REG 0x08
#define AB8500_RTC_ALRM_MIN_MID_REG 0x09
#define AB8500_RTC_ALRM_MIN_HI_REG  0x0A
#define AB8500_RTC_STAT_REG     0x0B
#define AB8500_RTC_BKUP_CHG_REG     0x0C
#define AB8500_RTC_FORCE_BKUP_REG   0x0D
#define AB8500_RTC_CALIB_REG        0x0E
#define AB8500_RTC_SWITCH_STAT_REG  0x0F

/* RtcReadRequest bits */
#define RTC_READ_REQUEST        0x01
#define RTC_WRITE_REQUEST       0x02

/* RtcCtrl bits */
#define RTC_ALARM_ENA           0x04
#define RTC_STATUS_DATA         0x01

#define COUNTS_PER_SEC          (0xF000 / 60)
#define AB8500_RTC_EPOCH        2000

static const u8 ab8500_rtc_time_regs[] = {
    AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
    AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
    AB8500_RTC_WATCH_TSECMID_REG
};

static const u8 ab8500_rtc_alarm_regs[] = {
    AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
    AB8500_RTC_ALRM_MIN_LOW_REG
};

/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
static unsigned long get_elapsed_seconds(int year)
{
    unsigned long secs;
    struct rtc_time tm = {
        .tm_year = year - 1900,
        .tm_mday = 1,
    };

    /*
     * This function calculates secs from 1970 and not from
     * 1900, even if we supply the offset from year 1900.
     */
    rtc_tm_to_time(&tm, &secs);
    return secs;
}

static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    unsigned long timeout = jiffies + HZ;
    int retval, i;
    unsigned long mins, secs;
    unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
    u8 value;

    /* Request a data read */
    retval = abx500_set_register_interruptible(dev,
        AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
    if (retval < 0)
        return retval;

    /* Wait for some cycles after enabling the rtc read in ab8500 */
    while (time_before(jiffies, timeout)) {
        retval = abx500_get_register_interruptible(dev,
            AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
        if (retval < 0)
            return retval;

        if (!(value & RTC_READ_REQUEST))
            break;

        usleep_range(1000, 5000);
    }

    /* Read the Watchtime registers */
    for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
        retval = abx500_get_register_interruptible(dev,
            AB8500_RTC, ab8500_rtc_time_regs[i], &value);
        if (retval < 0)
            return retval;
        buf[i] = value;
    }

    mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];

    secs =  (buf[3] << 8) | buf[4];
    secs =  secs / COUNTS_PER_SEC;
    secs =  secs + (mins * 60);

    /* Add back the initially subtracted number of seconds */
    secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

    rtc_time_to_tm(secs, tm);
    return rtc_valid_tm(tm);
}

static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    int retval, i;
    unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
    unsigned long no_secs, no_mins, secs = 0;

    if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
        dev_dbg(dev, "year should be equal to or greater than %d\n",
                AB8500_RTC_EPOCH);
        return -EINVAL;
    }

    /* Get the number of seconds since 1970 */
    rtc_tm_to_time(tm, &secs);

    /*
     * Convert it to the number of seconds since 01-01-2000 00:00:00, since
     * we only have a small counter in the RTC.
     */
    secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

    no_mins = secs / 60;

    no_secs = secs % 60;
    /* Make the seconds count as per the RTC resolution */
    no_secs = no_secs * COUNTS_PER_SEC;

    buf[4] = no_secs & 0xFF;
    buf[3] = (no_secs >> 8) & 0xFF;

    buf[2] = no_mins & 0xFF;
    buf[1] = (no_mins >> 8) & 0xFF;
    buf[0] = (no_mins >> 16) & 0xFF;

    for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
        retval = abx500_set_register_interruptible(dev, AB8500_RTC,
            ab8500_rtc_time_regs[i], buf[i]);
        if (retval < 0)
            return retval;
    }

    /* Request a data write */
    return abx500_set_register_interruptible(dev, AB8500_RTC,
        AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
}

static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
    int retval, i;
    u8 rtc_ctrl, value;
    unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
    unsigned long secs, mins;

    /* Check if the alarm is enabled or not */
    retval = abx500_get_register_interruptible(dev, AB8500_RTC,
        AB8500_RTC_STAT_REG, &rtc_ctrl);
    if (retval < 0)
        return retval;

    if (rtc_ctrl & RTC_ALARM_ENA)
        alarm->enabled = 1;
    else
        alarm->enabled = 0;

    alarm->pending = 0;

    for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
        retval = abx500_get_register_interruptible(dev, AB8500_RTC,
            ab8500_rtc_alarm_regs[i], &value);
        if (retval < 0)
            return retval;
        buf[i] = value;
    }

    mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
    secs = mins * 60;

    /* Add back the initially subtracted number of seconds */
    secs += get_elapsed_seconds(AB8500_RTC_EPOCH);

    rtc_time_to_tm(secs, &alarm->time);

    return rtc_valid_tm(&alarm->time);
}

static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
    return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
        AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
        enabled ? RTC_ALARM_ENA : 0);
}

static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
    int retval, i;
    unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
    unsigned long mins, secs = 0, cursec = 0;
    struct rtc_time curtm;

    if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
        dev_dbg(dev, "year should be equal to or greater than %d\n",
                AB8500_RTC_EPOCH);
        return -EINVAL;
    }

    /* Get the number of seconds since 1970 */
    rtc_tm_to_time(&alarm->time, &secs);

    /*
     * Check whether alarm is set less than 1min.
     * Since our RTC doesn't support alarm resolution less than 1min,
     * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
     */
    ab8500_rtc_read_time(dev, &curtm); /* Read current time */
    rtc_tm_to_time(&curtm, &cursec);
    if ((secs - cursec) < 59) {
        dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
        return -EINVAL;
    }

    /*
     * Convert it to the number of seconds since 01-01-2000 00:00:00, since
     * we only have a small counter in the RTC.
     */
    secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);

    mins = secs / 60;

    buf[2] = mins & 0xFF;
    buf[1] = (mins >> 8) & 0xFF;
    buf[0] = (mins >> 16) & 0xFF;

    /* Set the alarm time */
    for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
        retval = abx500_set_register_interruptible(dev, AB8500_RTC,
            ab8500_rtc_alarm_regs[i], buf[i]);
        if (retval < 0)
            return retval;
    }

    return ab8500_rtc_irq_enable(dev, alarm->enabled);
}


static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
{
    int retval;
    u8  rtccal = 0;

    /*
     * Check that the calibration value (which is in units of 0.5
     * parts-per-million) is in the AB8500's range for RtcCalibration
     * register. -128 (0x80) is not permitted because the AB8500 uses
     * a sign-bit rather than two's complement, so 0x80 is just another
     * representation of zero.
     */
    if ((calibration < -127) || (calibration > 127)) {
        dev_err(dev, "RtcCalibration value outside permitted range\n");
        return -EINVAL;
    }

    /*
     * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
     * so need to convert to this sort of representation before writing
     * into RtcCalibration register...
     */
    if (calibration >= 0)
        rtccal = 0x7F & calibration;
    else
        rtccal = ~(calibration - 1) | 0x80;

    retval = abx500_set_register_interruptible(dev, AB8500_RTC,
            AB8500_RTC_CALIB_REG, rtccal);

    return retval;
}

static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
{
    int retval;
    u8  rtccal = 0;

    retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
            AB8500_RTC_CALIB_REG, &rtccal);
    if (retval >= 0) {
        /*
         * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
         * so need to convert value from RtcCalibration register into
         * a two's complement signed value...
         */
        if (rtccal & 0x80)
            *calibration = 0 - (rtccal & 0x7F);
        else
            *calibration = 0x7F & rtccal;
    }

    return retval;
}

static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t count)
{
    int retval;
    int calibration = 0;

    if (sscanf(buf, " %i ", &calibration) != 1) {
        dev_err(dev, "Failed to store RTC calibration attribute\n");
        return -EINVAL;
    }

    retval = ab8500_rtc_set_calibration(dev, calibration);

    return retval ? retval : count;
}

static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    int  retval = 0;
    int  calibration = 0;

    retval = ab8500_rtc_get_calibration(dev, &calibration);
    if (retval < 0) {
        dev_err(dev, "Failed to read RTC calibration attribute\n");
        sprintf(buf, "0\n");
        return retval;
    }

    return sprintf(buf, "%d\n", calibration);
}

static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
           ab8500_sysfs_show_rtc_calibration,
           ab8500_sysfs_store_rtc_calibration);

static int ab8500_sysfs_rtc_register(struct device *dev)
{
    return device_create_file(dev, &dev_attr_rtc_calibration);
}

static void ab8500_sysfs_rtc_unregister(struct device *dev)
{
    device_remove_file(dev, &dev_attr_rtc_calibration);
}

static irqreturn_t rtc_alarm_handler(int irq, void *data)
{
    struct rtc_device *rtc = data;
    unsigned long events = RTC_IRQF | RTC_AF;

    dev_dbg(&rtc->dev, "%s\n", __func__);
    rtc_update_irq(rtc, 1, events);

    return IRQ_HANDLED;
}

static const struct rtc_class_ops ab8500_rtc_ops = {
    .read_time      = ab8500_rtc_read_time,
    .set_time       = ab8500_rtc_set_time,
    .read_alarm     = ab8500_rtc_read_alarm,
    .set_alarm      = ab8500_rtc_set_alarm,
    .alarm_irq_enable   = ab8500_rtc_irq_enable,
};

static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
{
    int err;
    struct rtc_device *rtc;
    u8 rtc_ctrl;
    int irq;

    irq = platform_get_irq_byname(pdev, "ALARM");
    if (irq < 0)
        return irq;

    /* For RTC supply test */
    err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
        AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
    if (err < 0)
        return err;

    /* Wait for reset by the PorRtc */
    usleep_range(1000, 5000);

    err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
        AB8500_RTC_STAT_REG, &rtc_ctrl);
    if (err < 0)
        return err;

    /* Check if the RTC Supply fails */
    if (!(rtc_ctrl & RTC_STATUS_DATA)) {
        dev_err(&pdev->dev, "RTC supply failure\n");
        return -ENODEV;
    }

    device_init_wakeup(&pdev->dev, true);

    rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
            THIS_MODULE);
    if (IS_ERR(rtc)) {
        dev_err(&pdev->dev, "Registration failed\n");
        err = PTR_ERR(rtc);
        return err;
    }

    err = request_threaded_irq(irq, NULL, rtc_alarm_handler,
        IRQF_NO_SUSPEND | IRQF_ONESHOT, "ab8500-rtc", rtc);
    if (err < 0) {
        rtc_device_unregister(rtc);
        return err;
    }

    platform_set_drvdata(pdev, rtc);

    err = ab8500_sysfs_rtc_register(&pdev->dev);
    if (err) {
        dev_err(&pdev->dev, "sysfs RTC failed to register\n");
        return err;
    }

    return 0;
}

static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
{
    struct rtc_device *rtc = platform_get_drvdata(pdev);
    int irq = platform_get_irq_byname(pdev, "ALARM");

    ab8500_sysfs_rtc_unregister(&pdev->dev);

    free_irq(irq, rtc);
    rtc_device_unregister(rtc);
    platform_set_drvdata(pdev, NULL);

    return 0;
}

static struct platform_driver ab8500_rtc_driver = {
    .driver = {
        .name = "ab8500-rtc",
        .owner = THIS_MODULE,
    },
    .probe  = ab8500_rtc_probe,
    .remove = __devexit_p(ab8500_rtc_remove),
};

module_platform_driver(ab8500_rtc_driver);

MODULE_AUTHOR("Virupax Sadashivpetimath <[email protected]>");
MODULE_DESCRIPTION("AB8500 RTC Driver");
MODULE_LICENSE("GPL v2");