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        void __iomem *ioaddr_nvram;
  56        void __iomem *ioaddr_rtc;
  57        size_t size_nvram;
  58        unsigned long last_jiffies;
  59        struct bin_attribute nvram_attr;
  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        return rtc_valid_tm(tm);
 119}
 120
 121static const struct rtc_class_ops ds1742_rtc_ops = {
 122        .read_time      = ds1742_rtc_read_time,
 123        .set_time       = ds1742_rtc_set_time,
 124};
 125
 126static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
 127                                 struct bin_attribute *bin_attr,
 128                                 char *buf, loff_t pos, size_t size)
 129{
 130        struct device *dev = container_of(kobj, struct device, kobj);
 131        struct platform_device *pdev = to_platform_device(dev);
 132        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 133        void __iomem *ioaddr = pdata->ioaddr_nvram;
 134        ssize_t count;
 135
 136        for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 137                *buf++ = readb(ioaddr + pos++);
 138        return count;
 139}
 140
 141static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
 142                                  struct bin_attribute *bin_attr,
 143                                  char *buf, loff_t pos, size_t size)
 144{
 145        struct device *dev = container_of(kobj, struct device, kobj);
 146        struct platform_device *pdev = to_platform_device(dev);
 147        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 148        void __iomem *ioaddr = pdata->ioaddr_nvram;
 149        ssize_t count;
 150
 151        for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 152                writeb(*buf++, ioaddr + pos++);
 153        return count;
 154}
 155
 156static int ds1742_rtc_probe(struct platform_device *pdev)
 157{
 158        struct rtc_device *rtc;
 159        struct resource *res;
 160        unsigned int cen, sec;
 161        struct rtc_plat_data *pdata;
 162        void __iomem *ioaddr;
 163        int ret = 0;
 164
 165        pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 166        if (!pdata)
 167                return -ENOMEM;
 168
 169        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 170        ioaddr = devm_ioremap_resource(&pdev->dev, res);
 171        if (IS_ERR(ioaddr))
 172                return PTR_ERR(ioaddr);
 173
 174        pdata->ioaddr_nvram = ioaddr;
 175        pdata->size_nvram = resource_size(res) - RTC_SIZE;
 176        pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 177
 178        sysfs_bin_attr_init(&pdata->nvram_attr);
 179        pdata->nvram_attr.attr.name = "nvram";
 180        pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 181        pdata->nvram_attr.read = ds1742_nvram_read;
 182        pdata->nvram_attr.write = ds1742_nvram_write;
 183        pdata->nvram_attr.size = pdata->size_nvram;
 184
 185        /* turn RTC on if it was not on */
 186        ioaddr = pdata->ioaddr_rtc;
 187        sec = readb(ioaddr + RTC_SECONDS);
 188        if (sec & RTC_STOP) {
 189                sec &= RTC_SECONDS_MASK;
 190                cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 191                writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 192                writeb(sec, ioaddr + RTC_SECONDS);
 193                writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 194        }
 195        if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 196                dev_warn(&pdev->dev, "voltage-low detected.\n");
 197
 198        pdata->last_jiffies = jiffies;
 199        platform_set_drvdata(pdev, pdata);
 200        rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 201                                  &ds1742_rtc_ops, THIS_MODULE);
 202        if (IS_ERR(rtc))
 203                return PTR_ERR(rtc);
 204
 205        ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 206
 207        return ret;
 208}
 209
 210static int ds1742_rtc_remove(struct platform_device *pdev)
 211{
 212        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 213
 214        sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 215        return 0;
 216}
 217
 218static struct platform_driver ds1742_rtc_driver = {
 219        .probe          = ds1742_rtc_probe,
 220        .remove         = ds1742_rtc_remove,
 221        .driver         = {
 222                .name   = "rtc-ds1742",
 223                .owner  = THIS_MODULE,
 224        },
 225};
 226
 227module_platform_driver(ds1742_rtc_driver);
 228
 229MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 230MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 231MODULE_LICENSE("GPL");
 232MODULE_VERSION(DRV_VERSION);
 233MODULE_ALIAS("platform:rtc-ds1742");
 234
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