rtc-ds1742.c

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/*
 * An rtc driver for the Dallas DS1742
 *
 * Copyright (C) 2006 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.
 *
 * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <[email protected]>
 *  - nvram size determined from resource
 *  - this ds1742 driver now supports ds1743.
 */

#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/rtc.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/module.h>

#define DRV_VERSION "0.4"

#define RTC_SIZE        8

#define RTC_CONTROL     0
#define RTC_CENTURY     0
#define RTC_SECONDS     1
#define RTC_MINUTES     2
#define RTC_HOURS       3
#define RTC_DAY         4
#define RTC_DATE        5
#define RTC_MONTH       6
#define RTC_YEAR        7

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

/* Bits in the Control/Century register */
#define RTC_WRITE       0x80
#define RTC_READ        0x40

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

/* Bits in the Day register */
#define RTC_BATT_FLAG       0x80

struct rtc_plat_data {
    struct rtc_device *rtc;
    void __iomem *ioaddr_nvram;
    void __iomem *ioaddr_rtc;
    size_t size_nvram;
    size_t size;
    unsigned long last_jiffies;
    struct bin_attribute nvram_attr;
};

static int ds1742_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_rtc;
    u8 century;

    century = bin2bcd((tm->tm_year + 1900) / 100);

    writeb(RTC_WRITE, ioaddr + RTC_CONTROL);

    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);

    /* RTC_CENTURY and RTC_CONTROL share same register */
    writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
    writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
    return 0;
}

static int ds1742_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_rtc;
    unsigned int year, month, day, hour, minute, second, week;
    unsigned int century;

    /* give enough time to update RTC in case of continuous read */
    if (pdata->last_jiffies == jiffies)
        msleep(1);
    pdata->last_jiffies = jiffies;
    writeb(RTC_READ, ioaddr + RTC_CONTROL);
    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) & RTC_CENTURY_MASK;
    writeb(0, ioaddr + RTC_CONTROL);
    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 const struct rtc_class_ops ds1742_rtc_ops = {
    .read_time  = ds1742_rtc_read_time,
    .set_time   = ds1742_rtc_set_time,
};

static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
                 struct bin_attribute *bin_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_nvram;
    ssize_t count;

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

static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
                  struct bin_attribute *bin_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_nvram;
    ssize_t count;

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

static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
{
    struct rtc_device *rtc;
    struct resource *res;
    unsigned int cen, sec;
    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;
    pdata->size = resource_size(res);
    if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
        pdev->name))
        return -EBUSY;
    ioaddr = devm_ioremap(&pdev->dev, res->start, pdata->size);
    if (!ioaddr)
        return -ENOMEM;

    pdata->ioaddr_nvram = ioaddr;
    pdata->size_nvram = pdata->size - RTC_SIZE;
    pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;

    sysfs_bin_attr_init(&pdata->nvram_attr);
    pdata->nvram_attr.attr.name = "nvram";
    pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
    pdata->nvram_attr.read = ds1742_nvram_read;
    pdata->nvram_attr.write = ds1742_nvram_write;
    pdata->nvram_attr.size = pdata->size_nvram;

    /* turn RTC on if it was not on */
    ioaddr = pdata->ioaddr_rtc;
    sec = readb(ioaddr + RTC_SECONDS);
    if (sec & RTC_STOP) {
        sec &= RTC_SECONDS_MASK;
        cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
        writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
        writeb(sec, ioaddr + RTC_SECONDS);
        writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
    }
    if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
        dev_warn(&pdev->dev, "voltage-low detected.\n");

    pdata->last_jiffies = jiffies;
    platform_set_drvdata(pdev, pdata);
    rtc = rtc_device_register(pdev->name, &pdev->dev,
                  &ds1742_rtc_ops, THIS_MODULE);
    if (IS_ERR(rtc))
        return PTR_ERR(rtc);
    pdata->rtc = rtc;

    ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
    if (ret) {
        dev_err(&pdev->dev, "creating nvram file in sysfs failed\n");
        rtc_device_unregister(rtc);
    }
    return ret;
}

static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
{
    struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

    sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
    rtc_device_unregister(pdata->rtc);
    return 0;
}

static struct platform_driver ds1742_rtc_driver = {
    .probe      = ds1742_rtc_probe,
    .remove     = __devexit_p(ds1742_rtc_remove),
    .driver     = {
        .name   = "rtc-ds1742",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(ds1742_rtc_driver);

MODULE_AUTHOR("Atsushi Nemoto <[email protected]>");
MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:rtc-ds1742");