rtc-spear.c

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/*
 * drivers/rtc/rtc-spear.c
 *
 * Copyright (C) 2010 ST Microelectronics
 * Rajeev Kumar<[email protected]>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/bcd.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

/* RTC registers */
#define TIME_REG        0x00
#define DATE_REG        0x04
#define ALARM_TIME_REG      0x08
#define ALARM_DATE_REG      0x0C
#define CTRL_REG        0x10
#define STATUS_REG      0x14

/* TIME_REG & ALARM_TIME_REG */
#define SECONDS_UNITS       (0xf<<0)    /* seconds units position */
#define SECONDS_TENS        (0x7<<4)    /* seconds tens position */
#define MINUTES_UNITS       (0xf<<8)    /* minutes units position */
#define MINUTES_TENS        (0x7<<12)   /* minutes tens position */
#define HOURS_UNITS     (0xf<<16)   /* hours units position */
#define HOURS_TENS      (0x3<<20)   /* hours tens position */

/* DATE_REG & ALARM_DATE_REG */
#define DAYS_UNITS      (0xf<<0)    /* days units position */
#define DAYS_TENS       (0x3<<4)    /* days tens position */
#define MONTHS_UNITS        (0xf<<8)    /* months units position */
#define MONTHS_TENS     (0x1<<12)   /* months tens position */
#define YEARS_UNITS     (0xf<<16)   /* years units position */
#define YEARS_TENS      (0xf<<20)   /* years tens position */
#define YEARS_HUNDREDS      (0xf<<24)   /* years hundereds position */
#define YEARS_MILLENIUMS    (0xf<<28)   /* years millenium position */

/* MASK SHIFT TIME_REG & ALARM_TIME_REG*/
#define SECOND_SHIFT        0x00        /* seconds units */
#define MINUTE_SHIFT        0x08        /* minutes units position */
#define HOUR_SHIFT      0x10        /* hours units position */
#define MDAY_SHIFT      0x00        /* Month day shift */
#define MONTH_SHIFT     0x08        /* Month shift */
#define YEAR_SHIFT      0x10        /* Year shift */

#define SECOND_MASK     0x7F
#define MIN_MASK        0x7F
#define HOUR_MASK       0x3F
#define DAY_MASK        0x3F
#define MONTH_MASK      0x7F
#define YEAR_MASK       0xFFFF

/* date reg equal to time reg, for debug only */
#define TIME_BYP        (1<<9)
#define INT_ENABLE      (1<<31)     /* interrupt enable */

/* STATUS_REG */
#define CLK_UNCONNECTED     (1<<0)
#define PEND_WR_TIME        (1<<2)
#define PEND_WR_DATE        (1<<3)
#define LOST_WR_TIME        (1<<4)
#define LOST_WR_DATE        (1<<5)
#define RTC_INT_MASK        (1<<31)
#define STATUS_BUSY     (PEND_WR_TIME | PEND_WR_DATE)
#define STATUS_FAIL     (LOST_WR_TIME | LOST_WR_DATE)

struct spear_rtc_config {
    struct rtc_device *rtc;
    struct clk *clk;
    spinlock_t lock;
    void __iomem *ioaddr;
    unsigned int irq_wake;
};

static inline void spear_rtc_clear_interrupt(struct spear_rtc_config *config)
{
    unsigned int val;
    unsigned long flags;

    spin_lock_irqsave(&config->lock, flags);
    val = readl(config->ioaddr + STATUS_REG);
    val |= RTC_INT_MASK;
    writel(val, config->ioaddr + STATUS_REG);
    spin_unlock_irqrestore(&config->lock, flags);
}

static inline void spear_rtc_enable_interrupt(struct spear_rtc_config *config)
{
    unsigned int val;

    val = readl(config->ioaddr + CTRL_REG);
    if (!(val & INT_ENABLE)) {
        spear_rtc_clear_interrupt(config);
        val |= INT_ENABLE;
        writel(val, config->ioaddr + CTRL_REG);
    }
}

static inline void spear_rtc_disable_interrupt(struct spear_rtc_config *config)
{
    unsigned int val;

    val = readl(config->ioaddr + CTRL_REG);
    if (val & INT_ENABLE) {
        val &= ~INT_ENABLE;
        writel(val, config->ioaddr + CTRL_REG);
    }
}

static inline int is_write_complete(struct spear_rtc_config *config)
{
    int ret = 0;
    unsigned long flags;

    spin_lock_irqsave(&config->lock, flags);
    if ((readl(config->ioaddr + STATUS_REG)) & STATUS_FAIL)
        ret = -EIO;
    spin_unlock_irqrestore(&config->lock, flags);

    return ret;
}

static void rtc_wait_not_busy(struct spear_rtc_config *config)
{
    int status, count = 0;
    unsigned long flags;

    /* Assuming BUSY may stay active for 80 msec) */
    for (count = 0; count < 80; count++) {
        spin_lock_irqsave(&config->lock, flags);
        status = readl(config->ioaddr + STATUS_REG);
        spin_unlock_irqrestore(&config->lock, flags);
        if ((status & STATUS_BUSY) == 0)
            break;
        /* check status busy, after each msec */
        msleep(1);
    }
}

static irqreturn_t spear_rtc_irq(int irq, void *dev_id)
{
    struct spear_rtc_config *config = dev_id;
    unsigned long flags, events = 0;
    unsigned int irq_data;

    spin_lock_irqsave(&config->lock, flags);
    irq_data = readl(config->ioaddr + STATUS_REG);
    spin_unlock_irqrestore(&config->lock, flags);

    if ((irq_data & RTC_INT_MASK)) {
        spear_rtc_clear_interrupt(config);
        events = RTC_IRQF | RTC_AF;
        rtc_update_irq(config->rtc, 1, events);
        return IRQ_HANDLED;
    } else
        return IRQ_NONE;

}

static int tm2bcd(struct rtc_time *tm)
{
    if (rtc_valid_tm(tm) != 0)
        return -EINVAL;
    tm->tm_sec = bin2bcd(tm->tm_sec);
    tm->tm_min = bin2bcd(tm->tm_min);
    tm->tm_hour = bin2bcd(tm->tm_hour);
    tm->tm_mday = bin2bcd(tm->tm_mday);
    tm->tm_mon = bin2bcd(tm->tm_mon + 1);
    tm->tm_year = bin2bcd(tm->tm_year);

    return 0;
}

static void bcd2tm(struct rtc_time *tm)
{
    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) - 1;
    /* epoch == 1900 */
    tm->tm_year = bcd2bin(tm->tm_year);
}

/*
 * spear_rtc_read_time - set the time
 * @dev: rtc device in use
 * @tm: holds date and time
 *
 * This function read time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    struct spear_rtc_config *config = dev_get_drvdata(dev);
    unsigned int time, date;

    /* we don't report wday/yday/isdst ... */
    rtc_wait_not_busy(config);

    time = readl(config->ioaddr + TIME_REG);
    date = readl(config->ioaddr + DATE_REG);
    tm->tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
    tm->tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
    tm->tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
    tm->tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
    tm->tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
    tm->tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

    bcd2tm(tm);
    return 0;
}

/*
 * spear_rtc_set_time - set the time
 * @dev: rtc device in use
 * @tm: holds date and time
 *
 * This function set time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    struct spear_rtc_config *config = dev_get_drvdata(dev);
    unsigned int time, date;

    if (tm2bcd(tm) < 0)
        return -EINVAL;

    rtc_wait_not_busy(config);
    time = (tm->tm_sec << SECOND_SHIFT) | (tm->tm_min << MINUTE_SHIFT) |
        (tm->tm_hour << HOUR_SHIFT);
    date = (tm->tm_mday << MDAY_SHIFT) | (tm->tm_mon << MONTH_SHIFT) |
        (tm->tm_year << YEAR_SHIFT);
    writel(time, config->ioaddr + TIME_REG);
    writel(date, config->ioaddr + DATE_REG);

    return is_write_complete(config);
}

/*
 * spear_rtc_read_alarm - read the alarm time
 * @dev: rtc device in use
 * @alm: holds alarm date and time
 *
 * This function read alarm time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    struct spear_rtc_config *config = dev_get_drvdata(dev);
    unsigned int time, date;

    rtc_wait_not_busy(config);

    time = readl(config->ioaddr + ALARM_TIME_REG);
    date = readl(config->ioaddr + ALARM_DATE_REG);
    alm->time.tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
    alm->time.tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
    alm->time.tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
    alm->time.tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
    alm->time.tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
    alm->time.tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

    bcd2tm(&alm->time);
    alm->enabled = readl(config->ioaddr + CTRL_REG) & INT_ENABLE;

    return 0;
}

/*
 * spear_rtc_set_alarm - set the alarm time
 * @dev: rtc device in use
 * @alm: holds alarm date and time
 *
 * This function set alarm time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
    struct spear_rtc_config *config = dev_get_drvdata(dev);
    unsigned int time, date;
    int err;

    if (tm2bcd(&alm->time) < 0)
        return -EINVAL;

    rtc_wait_not_busy(config);

    time = (alm->time.tm_sec << SECOND_SHIFT) | (alm->time.tm_min <<
            MINUTE_SHIFT) | (alm->time.tm_hour << HOUR_SHIFT);
    date = (alm->time.tm_mday << MDAY_SHIFT) | (alm->time.tm_mon <<
            MONTH_SHIFT) | (alm->time.tm_year << YEAR_SHIFT);

    writel(time, config->ioaddr + ALARM_TIME_REG);
    writel(date, config->ioaddr + ALARM_DATE_REG);
    err = is_write_complete(config);
    if (err < 0)
        return err;

    if (alm->enabled)
        spear_rtc_enable_interrupt(config);
    else
        spear_rtc_disable_interrupt(config);

    return 0;
}

static int spear_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct spear_rtc_config *config = dev_get_drvdata(dev);
    int ret = 0;

    spear_rtc_clear_interrupt(config);

    switch (enabled) {
    case 0:
        /* alarm off */
        spear_rtc_disable_interrupt(config);
        break;
    case 1:
        /* alarm on */
        spear_rtc_enable_interrupt(config);
        break;
    default:
        ret = -EINVAL;
        break;
    }

    return ret;
}

static struct rtc_class_ops spear_rtc_ops = {
    .read_time = spear_rtc_read_time,
    .set_time = spear_rtc_set_time,
    .read_alarm = spear_rtc_read_alarm,
    .set_alarm = spear_rtc_set_alarm,
    .alarm_irq_enable = spear_alarm_irq_enable,
};

static int __devinit spear_rtc_probe(struct platform_device *pdev)
{
    struct resource *res;
    struct spear_rtc_config *config;
    int status = 0;
    int irq;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res) {
        dev_err(&pdev->dev, "no resource defined\n");
        return -EBUSY;
    }
    if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
        dev_err(&pdev->dev, "rtc region already claimed\n");
        return -EBUSY;
    }

    config = kzalloc(sizeof(*config), GFP_KERNEL);
    if (!config) {
        dev_err(&pdev->dev, "out of memory\n");
        status = -ENOMEM;
        goto err_release_region;
    }

    config->clk = clk_get(&pdev->dev, NULL);
    if (IS_ERR(config->clk)) {
        status = PTR_ERR(config->clk);
        goto err_kfree;
    }

    status = clk_enable(config->clk);
    if (status < 0)
        goto err_clk_put;

    config->ioaddr = ioremap(res->start, resource_size(res));
    if (!config->ioaddr) {
        dev_err(&pdev->dev, "ioremap fail\n");
        status = -ENOMEM;
        goto err_disable_clock;
    }

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

    config->rtc = rtc_device_register(pdev->name, &pdev->dev,
            &spear_rtc_ops, THIS_MODULE);
    if (IS_ERR(config->rtc)) {
        dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
                PTR_ERR(config->rtc));
        status = PTR_ERR(config->rtc);
        goto err_iounmap;
    }

    /* alarm irqs */
    irq = platform_get_irq(pdev, 0);
    if (irq < 0) {
        dev_err(&pdev->dev, "no update irq?\n");
        status = irq;
        goto err_clear_platdata;
    }

    status = request_irq(irq, spear_rtc_irq, 0, pdev->name, config);
    if (status) {
        dev_err(&pdev->dev, "Alarm interrupt IRQ%d already \
                claimed\n", irq);
        goto err_clear_platdata;
    }

    if (!device_can_wakeup(&pdev->dev))
        device_init_wakeup(&pdev->dev, 1);

    return 0;

err_clear_platdata:
    platform_set_drvdata(pdev, NULL);
    rtc_device_unregister(config->rtc);
err_iounmap:
    iounmap(config->ioaddr);
err_disable_clock:
    clk_disable(config->clk);
err_clk_put:
    clk_put(config->clk);
err_kfree:
    kfree(config);
err_release_region:
    release_mem_region(res->start, resource_size(res));

    return status;
}

static int __devexit spear_rtc_remove(struct platform_device *pdev)
{
    struct spear_rtc_config *config = platform_get_drvdata(pdev);
    int irq;
    struct resource *res;

    /* leave rtc running, but disable irqs */
    spear_rtc_disable_interrupt(config);
    device_init_wakeup(&pdev->dev, 0);
    irq = platform_get_irq(pdev, 0);
    if (irq)
        free_irq(irq, pdev);
    clk_disable(config->clk);
    clk_put(config->clk);
    iounmap(config->ioaddr);
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (res)
        release_mem_region(res->start, resource_size(res));
    platform_set_drvdata(pdev, NULL);
    rtc_device_unregister(config->rtc);
    kfree(config);

    return 0;
}

#ifdef CONFIG_PM

static int spear_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct spear_rtc_config *config = platform_get_drvdata(pdev);
    int irq;

    irq = platform_get_irq(pdev, 0);
    if (device_may_wakeup(&pdev->dev)) {
        if (!enable_irq_wake(irq))
            config->irq_wake = 1;
    } else {
        spear_rtc_disable_interrupt(config);
        clk_disable(config->clk);
    }

    return 0;
}

static int spear_rtc_resume(struct platform_device *pdev)
{
    struct spear_rtc_config *config = platform_get_drvdata(pdev);
    int irq;

    irq = platform_get_irq(pdev, 0);

    if (device_may_wakeup(&pdev->dev)) {
        if (config->irq_wake) {
            disable_irq_wake(irq);
            config->irq_wake = 0;
        }
    } else {
        clk_enable(config->clk);
        spear_rtc_enable_interrupt(config);
    }

    return 0;
}

#else
#define spear_rtc_suspend   NULL
#define spear_rtc_resume    NULL
#endif

static void spear_rtc_shutdown(struct platform_device *pdev)
{
    struct spear_rtc_config *config = platform_get_drvdata(pdev);

    spear_rtc_disable_interrupt(config);
    clk_disable(config->clk);
}

#ifdef CONFIG_OF
static const struct of_device_id spear_rtc_id_table[] = {
    { .compatible = "st,spear600-rtc" },
    {}
};
MODULE_DEVICE_TABLE(of, spear_rtc_id_table);
#endif

static struct platform_driver spear_rtc_driver = {
    .probe = spear_rtc_probe,
    .remove = __devexit_p(spear_rtc_remove),
    .suspend = spear_rtc_suspend,
    .resume = spear_rtc_resume,
    .shutdown = spear_rtc_shutdown,
    .driver = {
        .name = "rtc-spear",
        .of_match_table = of_match_ptr(spear_rtc_id_table),
    },
};

module_platform_driver(spear_rtc_driver);

MODULE_ALIAS("platform:rtc-spear");
MODULE_AUTHOR("Rajeev Kumar <[email protected]>");
MODULE_DESCRIPTION("ST SPEAr Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL");