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/gfp.h>
  19#include <linux/delay.h>
  20#include <linux/jiffies.h>
  21#include <linux/rtc.h>
  22#include <linux/platform_device.h>
  23#include <linux/io.h>
  24#include <linux/module.h>
  25
  26#define DRV_VERSION "0.4"
  27
  28#define RTC_SIZE                8
  29
  30#define RTC_CONTROL             0
  31#define RTC_CENTURY             0
  32#define RTC_SECONDS             1
  33#define RTC_MINUTES             2
  34#define RTC_HOURS               3
  35#define RTC_DAY                 4
  36#define RTC_DATE                5
  37#define RTC_MONTH               6
  38#define RTC_YEAR                7
  39
  40#define RTC_CENTURY_MASK        0x3f
  41#define RTC_SECONDS_MASK        0x7f
  42#define RTC_DAY_MASK            0x07
  43
  44/* Bits in the Control/Century register */
  45#define RTC_WRITE               0x80
  46#define RTC_READ                0x40
  47
  48/* Bits in the Seconds register */
  49#define RTC_STOP                0x80
  50
  51/* Bits in the Day register */
  52#define RTC_BATT_FLAG           0x80
  53
  54struct rtc_plat_data {
  55        struct rtc_device *rtc;
  56        void __iomem *ioaddr_nvram;
  57        void __iomem *ioaddr_rtc;
  58        size_t size_nvram;
  59        size_t size;
  60        unsigned long last_jiffies;
  61        struct bin_attribute nvram_attr;
  62};
  63
  64static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
  65{
  66        struct platform_device *pdev = to_platform_device(dev);
  67        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  68        void __iomem *ioaddr = pdata->ioaddr_rtc;
  69        u8 century;
  70
  71        century = bin2bcd((tm->tm_year + 1900) / 100);
  72
  73        writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
  74
  75        writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  76        writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  77        writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  78        writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  79        writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  80        writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  81        writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  82
  83        /* RTC_CENTURY and RTC_CONTROL share same register */
  84        writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
  85        writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  86        return 0;
  87}
  88
  89static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
  90{
  91        struct platform_device *pdev = to_platform_device(dev);
  92        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  93        void __iomem *ioaddr = pdata->ioaddr_rtc;
  94        unsigned int year, month, day, hour, minute, second, week;
  95        unsigned int century;
  96
  97        /* give enough time to update RTC in case of continuous read */
  98        if (pdata->last_jiffies == jiffies)
  99                msleep(1);
 100        pdata->last_jiffies = jiffies;
 101        writeb(RTC_READ, ioaddr + RTC_CONTROL);
 102        second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 103        minute = readb(ioaddr + RTC_MINUTES);
 104        hour = readb(ioaddr + RTC_HOURS);
 105        day = readb(ioaddr + RTC_DATE);
 106        week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 107        month = readb(ioaddr + RTC_MONTH);
 108        year = readb(ioaddr + RTC_YEAR);
 109        century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 110        writeb(0, ioaddr + RTC_CONTROL);
 111        tm->tm_sec = bcd2bin(second);
 112        tm->tm_min = bcd2bin(minute);
 113        tm->tm_hour = bcd2bin(hour);
 114        tm->tm_mday = bcd2bin(day);
 115        tm->tm_wday = bcd2bin(week);
 116        tm->tm_mon = bcd2bin(month) - 1;
 117        /* year is 1900 + tm->tm_year */
 118        tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 119
 120        if (rtc_valid_tm(tm) < 0) {
 121                dev_err(dev, "retrieved date/time is not valid.\n");
 122                rtc_time_to_tm(0, tm);
 123        }
 124        return 0;
 125}
 126
 127static const struct rtc_class_ops ds1742_rtc_ops = {
 128        .read_time      = ds1742_rtc_read_time,
 129        .set_time       = ds1742_rtc_set_time,
 130};
 131
 132static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
 133                                 struct bin_attribute *bin_attr,
 134                                 char *buf, loff_t pos, size_t size)
 135{
 136        struct device *dev = container_of(kobj, struct device, kobj);
 137        struct platform_device *pdev = to_platform_device(dev);
 138        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 139        void __iomem *ioaddr = pdata->ioaddr_nvram;
 140        ssize_t count;
 141
 142        for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 143                *buf++ = readb(ioaddr + pos++);
 144        return count;
 145}
 146
 147static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
 148                                  struct bin_attribute *bin_attr,
 149                                  char *buf, loff_t pos, size_t size)
 150{
 151        struct device *dev = container_of(kobj, struct device, kobj);
 152        struct platform_device *pdev = to_platform_device(dev);
 153        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 154        void __iomem *ioaddr = pdata->ioaddr_nvram;
 155        ssize_t count;
 156
 157        for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 158                writeb(*buf++, ioaddr + pos++);
 159        return count;
 160}
 161
 162static int ds1742_rtc_probe(struct platform_device *pdev)
 163{
 164        struct rtc_device *rtc;
 165        struct resource *res;
 166        unsigned int cen, sec;
 167        struct rtc_plat_data *pdata;
 168        void __iomem *ioaddr;
 169        int ret = 0;
 170
 171        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 172        if (!res)
 173                return -ENODEV;
 174        pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 175        if (!pdata)
 176                return -ENOMEM;
 177        pdata->size = resource_size(res);
 178        if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
 179                pdev->name))
 180                return -EBUSY;
 181        ioaddr = devm_ioremap(&pdev->dev, res->start, pdata->size);
 182        if (!ioaddr)
 183                return -ENOMEM;
 184
 185        pdata->ioaddr_nvram = ioaddr;
 186        pdata->size_nvram = pdata->size - RTC_SIZE;
 187        pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 188
 189        sysfs_bin_attr_init(&pdata->nvram_attr);
 190        pdata->nvram_attr.attr.name = "nvram";
 191        pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 192        pdata->nvram_attr.read = ds1742_nvram_read;
 193        pdata->nvram_attr.write = ds1742_nvram_write;
 194        pdata->nvram_attr.size = pdata->size_nvram;
 195
 196        /* turn RTC on if it was not on */
 197        ioaddr = pdata->ioaddr_rtc;
 198        sec = readb(ioaddr + RTC_SECONDS);
 199        if (sec & RTC_STOP) {
 200                sec &= RTC_SECONDS_MASK;
 201                cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 202                writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 203                writeb(sec, ioaddr + RTC_SECONDS);
 204                writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 205        }
 206        if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 207                dev_warn(&pdev->dev, "voltage-low detected.\n");
 208
 209        pdata->last_jiffies = jiffies;
 210        platform_set_drvdata(pdev, pdata);
 211        rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 212                                  &ds1742_rtc_ops, THIS_MODULE);
 213        if (IS_ERR(rtc))
 214                return PTR_ERR(rtc);
 215        pdata->rtc = rtc;
 216
 217        ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 218
 219        return ret;
 220}
 221
 222static int ds1742_rtc_remove(struct platform_device *pdev)
 223{
 224        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 225
 226        sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 227        return 0;
 228}
 229
 230static struct platform_driver ds1742_rtc_driver = {
 231        .probe          = ds1742_rtc_probe,
 232        .remove         = ds1742_rtc_remove,
 233        .driver         = {
 234                .name   = "rtc-ds1742",
 235                .owner  = THIS_MODULE,
 236        },
 237};
 238
 239module_platform_driver(ds1742_rtc_driver);
 240
 241MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 242MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 243MODULE_LICENSE("GPL");
 244MODULE_VERSION(DRV_VERSION);
 245MODULE_ALIAS("platform:rtc-ds1742");
 246
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