linux/drivers/rtc/rtc-ds1742.c
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   1/*
   2 * An rtc driver for the Dallas DS1742
   3 *
   4 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
  11 *  - nvram size determined from resource
  12 *  - this ds1742 driver now supports ds1743.
  13 */
  14
  15#include <linux/bcd.h>
  16#include <linux/init.h>
  17#include <linux/kernel.h>
  18#include <linux/delay.h>
  19#include <linux/jiffies.h>
  20#include <linux/rtc.h>
  21#include <linux/platform_device.h>
  22#include <linux/io.h>
  23
  24#define DRV_VERSION "0.3"
  25
  26#define RTC_SIZE                8
  27
  28#define RTC_CONTROL             0
  29#define RTC_CENTURY             0
  30#define RTC_SECONDS             1
  31#define RTC_MINUTES             2
  32#define RTC_HOURS               3
  33#define RTC_DAY                 4
  34#define RTC_DATE                5
  35#define RTC_MONTH               6
  36#define RTC_YEAR                7
  37
  38#define RTC_CENTURY_MASK        0x3f
  39#define RTC_SECONDS_MASK        0x7f
  40#define RTC_DAY_MASK            0x07
  41
  42/* Bits in the Control/Century register */
  43#define RTC_WRITE               0x80
  44#define RTC_READ                0x40
  45
  46/* Bits in the Seconds register */
  47#define RTC_STOP                0x80
  48
  49/* Bits in the Day register */
  50#define RTC_BATT_FLAG           0x80
  51
  52struct rtc_plat_data {
  53        struct rtc_device *rtc;
  54        void __iomem *ioaddr_nvram;
  55        void __iomem *ioaddr_rtc;
  56        size_t size_nvram;
  57        size_t size;
  58        resource_size_t baseaddr;
  59        unsigned long last_jiffies;
  60};
  61
  62static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
  63{
  64        struct platform_device *pdev = to_platform_device(dev);
  65        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  66        void __iomem *ioaddr = pdata->ioaddr_rtc;
  67        u8 century;
  68
  69        century = bin2bcd((tm->tm_year + 1900) / 100);
  70
  71        writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
  72
  73        writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  74        writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  75        writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  76        writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  77        writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  78        writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  79        writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  80
  81        /* RTC_CENTURY and RTC_CONTROL share same register */
  82        writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
  83        writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  84        return 0;
  85}
  86
  87static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
  88{
  89        struct platform_device *pdev = to_platform_device(dev);
  90        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  91        void __iomem *ioaddr = pdata->ioaddr_rtc;
  92        unsigned int year, month, day, hour, minute, second, week;
  93        unsigned int century;
  94
  95        /* give enough time to update RTC in case of continuous read */
  96        if (pdata->last_jiffies == jiffies)
  97                msleep(1);
  98        pdata->last_jiffies = jiffies;
  99        writeb(RTC_READ, ioaddr + RTC_CONTROL);
 100        second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 101        minute = readb(ioaddr + RTC_MINUTES);
 102        hour = readb(ioaddr + RTC_HOURS);
 103        day = readb(ioaddr + RTC_DATE);
 104        week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 105        month = readb(ioaddr + RTC_MONTH);
 106        year = readb(ioaddr + RTC_YEAR);
 107        century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 108        writeb(0, ioaddr + RTC_CONTROL);
 109        tm->tm_sec = bcd2bin(second);
 110        tm->tm_min = bcd2bin(minute);
 111        tm->tm_hour = bcd2bin(hour);
 112        tm->tm_mday = bcd2bin(day);
 113        tm->tm_wday = bcd2bin(week);
 114        tm->tm_mon = bcd2bin(month) - 1;
 115        /* year is 1900 + tm->tm_year */
 116        tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 117
 118        if (rtc_valid_tm(tm) < 0) {
 119                dev_err(dev, "retrieved date/time is not valid.\n");
 120                rtc_time_to_tm(0, tm);
 121        }
 122        return 0;
 123}
 124
 125static const struct rtc_class_ops ds1742_rtc_ops = {
 126        .read_time      = ds1742_rtc_read_time,
 127        .set_time       = ds1742_rtc_set_time,
 128};
 129
 130static ssize_t ds1742_nvram_read(struct kobject *kobj,
 131                                 struct bin_attribute *bin_attr,
 132                                 char *buf, loff_t pos, size_t size)
 133{
 134        struct platform_device *pdev =
 135                to_platform_device(container_of(kobj, struct device, kobj));
 136        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 137        void __iomem *ioaddr = pdata->ioaddr_nvram;
 138        ssize_t count;
 139
 140        for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 141                *buf++ = readb(ioaddr + pos++);
 142        return count;
 143}
 144
 145static ssize_t ds1742_nvram_write(struct kobject *kobj,
 146                                  struct bin_attribute *bin_attr,
 147                                  char *buf, loff_t pos, size_t size)
 148{
 149        struct platform_device *pdev =
 150                to_platform_device(container_of(kobj, struct device, kobj));
 151        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 152        void __iomem *ioaddr = pdata->ioaddr_nvram;
 153        ssize_t count;
 154
 155        for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 156                writeb(*buf++, ioaddr + pos++);
 157        return count;
 158}
 159
 160static struct bin_attribute ds1742_nvram_attr = {
 161        .attr = {
 162                .name = "nvram",
 163                .mode = S_IRUGO | S_IWUSR,
 164        },
 165        .read = ds1742_nvram_read,
 166        .write = ds1742_nvram_write,
 167        /* REVISIT: size in sysfs won't match actual size... if it's
 168         * not a constant, each RTC should have its own attribute.
 169         */
 170};
 171
 172static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 173{
 174        struct rtc_device *rtc;
 175        struct resource *res;
 176        unsigned int cen, sec;
 177        struct rtc_plat_data *pdata = NULL;
 178        void __iomem *ioaddr = NULL;
 179        int ret = 0;
 180
 181        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 182        if (!res)
 183                return -ENODEV;
 184        pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
 185        if (!pdata)
 186                return -ENOMEM;
 187        pdata->size = res->end - res->start + 1;
 188        if (!request_mem_region(res->start, pdata->size, pdev->name)) {
 189                ret = -EBUSY;
 190                goto out;
 191        }
 192        pdata->baseaddr = res->start;
 193        ioaddr = ioremap(pdata->baseaddr, pdata->size);
 194        if (!ioaddr) {
 195                ret = -ENOMEM;
 196                goto out;
 197        }
 198        pdata->ioaddr_nvram = ioaddr;
 199        pdata->size_nvram = pdata->size - RTC_SIZE;
 200        pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 201
 202        /* turn RTC on if it was not on */
 203        ioaddr = pdata->ioaddr_rtc;
 204        sec = readb(ioaddr + RTC_SECONDS);
 205        if (sec & RTC_STOP) {
 206                sec &= RTC_SECONDS_MASK;
 207                cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 208                writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 209                writeb(sec, ioaddr + RTC_SECONDS);
 210                writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 211        }
 212        if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 213                dev_warn(&pdev->dev, "voltage-low detected.\n");
 214
 215        rtc = rtc_device_register(pdev->name, &pdev->dev,
 216                                  &ds1742_rtc_ops, THIS_MODULE);
 217        if (IS_ERR(rtc)) {
 218                ret = PTR_ERR(rtc);
 219                goto out;
 220        }
 221        pdata->rtc = rtc;
 222        pdata->last_jiffies = jiffies;
 223        platform_set_drvdata(pdev, pdata);
 224        ds1742_nvram_attr.size = max(ds1742_nvram_attr.size,
 225                                     pdata->size_nvram);
 226        ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
 227        if (ret)
 228                goto out;
 229        return 0;
 230 out:
 231        if (pdata->rtc)
 232                rtc_device_unregister(pdata->rtc);
 233        if (pdata->ioaddr_nvram)
 234                iounmap(pdata->ioaddr_nvram);
 235        if (pdata->baseaddr)
 236                release_mem_region(pdata->baseaddr, pdata->size);
 237        kfree(pdata);
 238        return ret;
 239}
 240
 241static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
 242{
 243        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 244
 245        sysfs_remove_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
 246        rtc_device_unregister(pdata->rtc);
 247        iounmap(pdata->ioaddr_nvram);
 248        release_mem_region(pdata->baseaddr, pdata->size);
 249        kfree(pdata);
 250        return 0;
 251}
 252
 253static struct platform_driver ds1742_rtc_driver = {
 254        .probe          = ds1742_rtc_probe,
 255        .remove         = __devexit_p(ds1742_rtc_remove),
 256        .driver         = {
 257                .name   = "rtc-ds1742",
 258                .owner  = THIS_MODULE,
 259        },
 260};
 261
 262static __init int ds1742_init(void)
 263{
 264        return platform_driver_register(&ds1742_rtc_driver);
 265}
 266
 267static __exit void ds1742_exit(void)
 268{
 269        platform_driver_unregister(&ds1742_rtc_driver);
 270}
 271
 272module_init(ds1742_init);
 273module_exit(ds1742_exit);
 274
 275MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 276MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 277MODULE_LICENSE("GPL");
 278MODULE_VERSION(DRV_VERSION);
 279MODULE_ALIAS("platform:rtc-ds1742");
 280
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