rtc-stk17ta8.c

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/*
 * A RTC driver for the Simtek STK17TA8
 *
 * By Thomas Hommel <[email protected]>
 *
 * Based on the DS1553 driver from
 * Atsushi Nemoto <[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.
 */

#include <linux/bcd.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/jiffies.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 "0.1"

#define RTC_REG_SIZE        0x20000
#define RTC_OFFSET      0x1fff0

#define RTC_FLAGS       (RTC_OFFSET + 0)
#define RTC_CENTURY     (RTC_OFFSET + 1)
#define RTC_SECONDS_ALARM   (RTC_OFFSET + 2)
#define RTC_MINUTES_ALARM   (RTC_OFFSET + 3)
#define RTC_HOURS_ALARM     (RTC_OFFSET + 4)
#define RTC_DATE_ALARM      (RTC_OFFSET + 5)
#define RTC_INTERRUPTS      (RTC_OFFSET + 6)
#define RTC_WATCHDOG        (RTC_OFFSET + 7)
#define RTC_CALIBRATION     (RTC_OFFSET + 8)
#define RTC_SECONDS     (RTC_OFFSET + 9)
#define RTC_MINUTES     (RTC_OFFSET + 10)
#define RTC_HOURS       (RTC_OFFSET + 11)
#define RTC_DAY         (RTC_OFFSET + 12)
#define RTC_DATE        (RTC_OFFSET + 13)
#define RTC_MONTH       (RTC_OFFSET + 14)
#define RTC_YEAR        (RTC_OFFSET + 15)

#define RTC_SECONDS_MASK    0x7f
#define RTC_DAY_MASK        0x07
#define RTC_CAL_MASK        0x3f

/* Bits in the Calibration register */
#define RTC_STOP        0x80

/* Bits in the Flags register */
#define RTC_FLAGS_AF        0x40
#define RTC_FLAGS_PF        0x20
#define RTC_WRITE       0x02
#define RTC_READ        0x01

/* Bits in the Interrupts register */
#define RTC_INTS_AIE        0x40

struct rtc_plat_data {
    struct rtc_device *rtc;
    void __iomem *ioaddr;
    unsigned long last_jiffies;
    int irq;
    unsigned int irqen;
    int alrm_sec;
    int alrm_min;
    int alrm_hour;
    int alrm_mday;
    spinlock_t lock;
};

static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
    void __iomem *ioaddr = pdata->ioaddr;
    u8 flags;

    flags = readb(pdata->ioaddr + RTC_FLAGS);
    writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);

    writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
    writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
    writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
    writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
    writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
    writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
    writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
    writeb(bin2bcd((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);

    writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
    return 0;
}

static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
    void __iomem *ioaddr = pdata->ioaddr;
    unsigned int year, month, day, hour, minute, second, week;
    unsigned int century;
    u8 flags;

    /* give enough time to update RTC in case of continuous read */
    if (pdata->last_jiffies == jiffies)
        msleep(1);
    pdata->last_jiffies = jiffies;

    flags = readb(pdata->ioaddr + RTC_FLAGS);
    writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
    second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
    minute = readb(ioaddr + RTC_MINUTES);
    hour = readb(ioaddr + RTC_HOURS);
    day = readb(ioaddr + RTC_DATE);
    week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
    month = readb(ioaddr + RTC_MONTH);
    year = readb(ioaddr + RTC_YEAR);
    century = readb(ioaddr + RTC_CENTURY);
    writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
    tm->tm_sec = bcd2bin(second);
    tm->tm_min = bcd2bin(minute);
    tm->tm_hour = bcd2bin(hour);
    tm->tm_mday = bcd2bin(day);
    tm->tm_wday = bcd2bin(week);
    tm->tm_mon = bcd2bin(month) - 1;
    /* year is 1900 + tm->tm_year */
    tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;

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

static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
{
    void __iomem *ioaddr = pdata->ioaddr;
    unsigned long irqflags;
    u8 flags;

    spin_lock_irqsave(&pdata->lock, irqflags);

    flags = readb(ioaddr + RTC_FLAGS);
    writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);

    writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_mday),
           ioaddr + RTC_DATE_ALARM);
    writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_hour),
           ioaddr + RTC_HOURS_ALARM);
    writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_min),
           ioaddr + RTC_MINUTES_ALARM);
    writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
           0x80 : bin2bcd(pdata->alrm_sec),
           ioaddr + RTC_SECONDS_ALARM);
    writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
    readb(ioaddr + RTC_FLAGS);  /* clear interrupts */
    writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
    spin_unlock_irqrestore(&pdata->lock, irqflags);
}

static int stk17ta8_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;
    stk17ta8_rtc_update_alarm(pdata);
    return 0;
}

static int stk17ta8_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 stk17ta8_rtc_interrupt(int irq, void *dev_id)
{
    struct platform_device *pdev = dev_id;
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
    void __iomem *ioaddr = pdata->ioaddr;
    unsigned long events = 0;

    spin_lock(&pdata->lock);
    /* read and clear interrupt */
    if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
        events = RTC_IRQF;
        if (readb(ioaddr + RTC_SECONDS_ALARM) & 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 stk17ta8_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;
    stk17ta8_rtc_update_alarm(pdata);
    return 0;
}

static const struct rtc_class_ops stk17ta8_rtc_ops = {
    .read_time      = stk17ta8_rtc_read_time,
    .set_time       = stk17ta8_rtc_set_time,
    .read_alarm     = stk17ta8_rtc_read_alarm,
    .set_alarm      = stk17ta8_rtc_set_alarm,
    .alarm_irq_enable   = stk17ta8_rtc_alarm_irq_enable,
};

static ssize_t stk17ta8_nvram_read(struct file *filp, struct kobject *kobj,
                 struct bin_attribute *attr, char *buf,
                 loff_t pos, size_t size)
{
    struct device *dev = container_of(kobj, struct device, kobj);
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
    void __iomem *ioaddr = pdata->ioaddr;
    ssize_t count;

    for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
        *buf++ = readb(ioaddr + pos++);
    return count;
}

static ssize_t stk17ta8_nvram_write(struct file *filp, struct kobject *kobj,
                  struct bin_attribute *attr, char *buf,
                  loff_t pos, size_t size)
{
    struct device *dev = container_of(kobj, struct device, kobj);
    struct platform_device *pdev = to_platform_device(dev);
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
    void __iomem *ioaddr = pdata->ioaddr;
    ssize_t count;

    for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
        writeb(*buf++, ioaddr + pos++);
    return count;
}

static struct bin_attribute stk17ta8_nvram_attr = {
    .attr = {
        .name = "nvram",
        .mode = S_IRUGO | S_IWUSR,
    },
    .size = RTC_OFFSET,
    .read = stk17ta8_nvram_read,
    .write = stk17ta8_nvram_write,
};

static int __devinit stk17ta8_rtc_probe(struct platform_device *pdev)
{
    struct resource *res;
    unsigned int cal;
    unsigned int flags;
    struct rtc_plat_data *pdata;
    void __iomem *ioaddr;
    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;
    if (!devm_request_mem_region(&pdev->dev, res->start, RTC_REG_SIZE,
            pdev->name))
        return -EBUSY;
    ioaddr = devm_ioremap(&pdev->dev, res->start, RTC_REG_SIZE);
    if (!ioaddr)
        return -ENOMEM;
    pdata->ioaddr = ioaddr;
    pdata->irq = platform_get_irq(pdev, 0);

    /* turn RTC on if it was not on */
    cal = readb(ioaddr + RTC_CALIBRATION);
    if (cal & RTC_STOP) {
        cal &= RTC_CAL_MASK;
        flags = readb(ioaddr + RTC_FLAGS);
        writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
        writeb(cal, ioaddr + RTC_CALIBRATION);
        writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
    }
    if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
        dev_warn(&pdev->dev, "voltage-low detected.\n");

    spin_lock_init(&pdata->lock);
    pdata->last_jiffies = jiffies;
    platform_set_drvdata(pdev, pdata);
    if (pdata->irq > 0) {
        writeb(0, ioaddr + RTC_INTERRUPTS);
        if (devm_request_irq(&pdev->dev, pdata->irq,
                stk17ta8_rtc_interrupt,
                IRQF_SHARED,
                pdev->name, pdev) < 0) {
            dev_warn(&pdev->dev, "interrupt not available.\n");
            pdata->irq = 0;
        }
    }

    pdata->rtc = rtc_device_register(pdev->name, &pdev->dev,
                  &stk17ta8_rtc_ops, THIS_MODULE);
    if (IS_ERR(pdata->rtc))
        return PTR_ERR(pdata->rtc);

    ret = sysfs_create_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
    if (ret)
        rtc_device_unregister(pdata->rtc);
    return ret;
}

static int __devexit stk17ta8_rtc_remove(struct platform_device *pdev)
{
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

    sysfs_remove_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
    rtc_device_unregister(pdata->rtc);
    if (pdata->irq > 0)
        writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
    return 0;
}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:stk17ta8");

static struct platform_driver stk17ta8_rtc_driver = {
    .probe      = stk17ta8_rtc_probe,
    .remove     = __devexit_p(stk17ta8_rtc_remove),
    .driver     = {
        .name   = "stk17ta8",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(stk17ta8_rtc_driver);

MODULE_AUTHOR("Thomas Hommel <[email protected]>");
MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);