rtc-ab3100.c

Go to the documentation of this file.

/*
 * Copyright (C) 2007-2009 ST-Ericsson AB
 * License terms: GNU General Public License (GPL) version 2
 * RTC clock driver for the AB3100 Analog Baseband Chip
 * Author: 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>

/* Clock rate in Hz */
#define AB3100_RTC_CLOCK_RATE   32768

/*
 * The AB3100 RTC registers. These are the same for
 * AB3000 and AB3100.
 * Control register:
 * Bit 0: RTC Monitor cleared=0, active=1, if you set it
 *        to 1 it remains active until RTC power is lost.
 * Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
 * Bit 2: Alarm on, 0 = off, 1 = on
 * Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
 */
#define AB3100_RTC      0x53
/* default setting, buffer disabled, alarm on */
#define RTC_SETTING     0x30
/* Alarm when AL0-AL3 == TI0-TI3  */
#define AB3100_AL0      0x56
#define AB3100_AL1      0x57
#define AB3100_AL2      0x58
#define AB3100_AL3      0x59
/* This 48-bit register that counts up at 32768 Hz */
#define AB3100_TI0      0x5a
#define AB3100_TI1      0x5b
#define AB3100_TI2      0x5c
#define AB3100_TI3      0x5d
#define AB3100_TI4      0x5e
#define AB3100_TI5      0x5f

/*
 * RTC clock functions and device struct declaration
 */
static int ab3100_rtc_set_mmss(struct device *dev, unsigned long secs)
{
    u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
             AB3100_TI3, AB3100_TI4, AB3100_TI5};
    unsigned char buf[6];
    u64 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
    int err = 0;
    int i;

    buf[0] = (fat_time) & 0xFF;
    buf[1] = (fat_time >> 8) & 0xFF;
    buf[2] = (fat_time >> 16) & 0xFF;
    buf[3] = (fat_time >> 24) & 0xFF;
    buf[4] = (fat_time >> 32) & 0xFF;
    buf[5] = (fat_time >> 40) & 0xFF;

    for (i = 0; i < 6; i++) {
        err = abx500_set_register_interruptible(dev, 0,
                            regs[i], buf[i]);
        if (err)
            return err;
    }

    /* Set the flag to mark that the clock is now set */
    return abx500_mask_and_set_register_interruptible(dev, 0,
                              AB3100_RTC,
                              0x01, 0x01);

}

static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    unsigned long time;
    u8 rtcval;
    int err;

    err = abx500_get_register_interruptible(dev, 0,
                        AB3100_RTC, &rtcval);
    if (err)
        return err;

    if (!(rtcval & 0x01)) {
        dev_info(dev, "clock not set (lost power)");
        return -EINVAL;
    } else {
        u64 fat_time;
        u8 buf[6];

        /* Read out time registers */
        err = abx500_get_register_page_interruptible(dev, 0,
                                 AB3100_TI0,
                                 buf, 6);
        if (err != 0)
            return err;

        fat_time = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
            ((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
            ((u64) buf[1] << 8) | (u64) buf[0];
        time = (unsigned long) (fat_time /
                    (u64) (AB3100_RTC_CLOCK_RATE * 2));
    }

    rtc_time_to_tm(time, tm);

    return rtc_valid_tm(tm);
}

static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
    unsigned long time;
    u64 fat_time;
    u8 buf[6];
    u8 rtcval;
    int err;

    /* Figure out if alarm is enabled or not */
    err = abx500_get_register_interruptible(dev, 0,
                        AB3100_RTC, &rtcval);
    if (err)
        return err;
    if (rtcval & 0x04)
        alarm->enabled = 1;
    else
        alarm->enabled = 0;
    /* No idea how this could be represented */
    alarm->pending = 0;
    /* Read out alarm registers, only 4 bytes */
    err = abx500_get_register_page_interruptible(dev, 0,
                             AB3100_AL0, buf, 4);
    if (err)
        return err;
    fat_time = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
        ((u64) buf[1] << 24) | ((u64) buf[0] << 16);
    time = (unsigned long) (fat_time / (u64) (AB3100_RTC_CLOCK_RATE * 2));

    rtc_time_to_tm(time, &alarm->time);

    return rtc_valid_tm(&alarm->time);
}

static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
    u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
    unsigned char buf[4];
    unsigned long secs;
    u64 fat_time;
    int err;
    int i;

    rtc_tm_to_time(&alarm->time, &secs);
    fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
    buf[0] = (fat_time >> 16) & 0xFF;
    buf[1] = (fat_time >> 24) & 0xFF;
    buf[2] = (fat_time >> 32) & 0xFF;
    buf[3] = (fat_time >> 40) & 0xFF;

    /* Set the alarm */
    for (i = 0; i < 4; i++) {
        err = abx500_set_register_interruptible(dev, 0,
                            regs[i], buf[i]);
        if (err)
            return err;
    }
    /* Then enable the alarm */
    return abx500_mask_and_set_register_interruptible(dev, 0,
                              AB3100_RTC, (1 << 2),
                              alarm->enabled << 2);
}

static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
    /*
     * It's not possible to enable/disable the alarm IRQ for this RTC.
     * It does not actually trigger any IRQ: instead its only function is
     * to power up the system, if it wasn't on. This will manifest as
     * a "power up cause" in the AB3100 power driver (battery charging etc)
     * and need to be handled there instead.
     */
    if (enabled)
        return abx500_mask_and_set_register_interruptible(dev, 0,
                            AB3100_RTC, (1 << 2),
                            1 << 2);
    else
        return abx500_mask_and_set_register_interruptible(dev, 0,
                            AB3100_RTC, (1 << 2),
                            0);
}

static const struct rtc_class_ops ab3100_rtc_ops = {
    .read_time  = ab3100_rtc_read_time,
    .set_mmss   = ab3100_rtc_set_mmss,
    .read_alarm = ab3100_rtc_read_alarm,
    .set_alarm  = ab3100_rtc_set_alarm,
    .alarm_irq_enable = ab3100_rtc_irq_enable,
};

static int __init ab3100_rtc_probe(struct platform_device *pdev)
{
    int err;
    u8 regval;
    struct rtc_device *rtc;

    /* The first RTC register needs special treatment */
    err = abx500_get_register_interruptible(&pdev->dev, 0,
                        AB3100_RTC, &regval);
    if (err) {
        dev_err(&pdev->dev, "unable to read RTC register\n");
        return -ENODEV;
    }

    if ((regval & 0xFE) != RTC_SETTING) {
        dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
             regval);
    }

    if ((regval & 1) == 0) {
        /*
         * Set bit to detect power loss.
         * This bit remains until RTC power is lost.
         */
        regval = 1 | RTC_SETTING;
        err = abx500_set_register_interruptible(&pdev->dev, 0,
                            AB3100_RTC, regval);
        /* Ignore any error on this write */
    }

    rtc = rtc_device_register("ab3100-rtc", &pdev->dev, &ab3100_rtc_ops,
                  THIS_MODULE);
    if (IS_ERR(rtc)) {
        err = PTR_ERR(rtc);
        return err;
    }
    platform_set_drvdata(pdev, rtc);

    return 0;
}

static int __exit ab3100_rtc_remove(struct platform_device *pdev)
{
    struct rtc_device *rtc = platform_get_drvdata(pdev);

    rtc_device_unregister(rtc);
    platform_set_drvdata(pdev, NULL);
    return 0;
}

static struct platform_driver ab3100_rtc_driver = {
    .driver = {
        .name = "ab3100-rtc",
        .owner = THIS_MODULE,
    },
    .remove  = __exit_p(ab3100_rtc_remove),
};

static int __init ab3100_rtc_init(void)
{
    return platform_driver_probe(&ab3100_rtc_driver,
                     ab3100_rtc_probe);
}

static void __exit ab3100_rtc_exit(void)
{
    platform_driver_unregister(&ab3100_rtc_driver);
}

module_init(ab3100_rtc_init);
module_exit(ab3100_rtc_exit);

MODULE_AUTHOR("Linus Walleij <[email protected]>");
MODULE_DESCRIPTION("AB3100 RTC Driver");
MODULE_LICENSE("GPL");