drivers/rtc/rtc-ds1742.c

   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 "0.4"
  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
  52 struct 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         unsigned long last_jiffies;
  59         struct bin_attribute nvram_attr;
  60 };
  61
  62 static 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
  87 static 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
 125 static const struct rtc_class_ops ds1742_rtc_ops = {
 126         .read_time      = ds1742_rtc_read_time,
 127         .set_time       = ds1742_rtc_set_time,
 128 };
 129
 130 static 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 device *dev = container_of(kobj, struct device, kobj);
 135         struct platform_device *pdev = to_platform_device(dev);
 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
 145 static 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 device *dev = container_of(kobj, struct device, kobj);
 150         struct platform_device *pdev = to_platform_device(dev);
 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
 160 static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 161 {
 162         struct rtc_device *rtc;
 163         struct resource *res;
 164         unsigned int cen, sec;
 165         struct rtc_plat_data *pdata;
 166         void __iomem *ioaddr;
 167         int ret = 0;
 168
 169         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 170         if (!res)
 171                 return -ENODEV;
 172         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 173         if (!pdata)
 174                 return -ENOMEM;
 175         pdata->size = res->end - res->start + 1;
 176         if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
 177                 pdev->name))
 178                 return -EBUSY;
 179         ioaddr = devm_ioremap(&pdev->dev, res->start, pdata->size);
 180         if (!ioaddr)
 181                 return -ENOMEM;
 182
 183         pdata->ioaddr_nvram = ioaddr;
 184         pdata->size_nvram = pdata->size - RTC_SIZE;
 185         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 186
 187         pdata->nvram_attr.attr.name = "nvram";
 188         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 189         pdata->nvram_attr.read = ds1742_nvram_read;
 190         pdata->nvram_attr.write = ds1742_nvram_write;
 191         pdata->nvram_attr.size = pdata->size_nvram;
 192
 193         /* turn RTC on if it was not on */
 194         ioaddr = pdata->ioaddr_rtc;
 195         sec = readb(ioaddr + RTC_SECONDS);
 196         if (sec & RTC_STOP) {
 197                 sec &= RTC_SECONDS_MASK;
 198                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 199                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 200                 writeb(sec, ioaddr + RTC_SECONDS);
 201                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 202         }
 203         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 204                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 205
 206         pdata->last_jiffies = jiffies;
 207         platform_set_drvdata(pdev, pdata);
 208         rtc = rtc_device_register(pdev->name, &pdev->dev,
 209                                   &ds1742_rtc_ops, THIS_MODULE);
 210         if (IS_ERR(rtc))
 211                 return PTR_ERR(rtc);
 212         pdata->rtc = rtc;
 213
 214         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 215         if (ret) {
 216                 dev_err(&pdev->dev, "creating nvram file in sysfs failed\n");
 217                 rtc_device_unregister(rtc);
 218         }
 219         return ret;
 220 }
 221
 222 static int __devexit 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         rtc_device_unregister(pdata->rtc);
 228         return 0;
 229 }
 230
 231 static struct platform_driver ds1742_rtc_driver = {
 232         .probe          = ds1742_rtc_probe,
 233         .remove         = __devexit_p(ds1742_rtc_remove),
 234         .driver         = {
 235                 .name   = "rtc-ds1742",
 236                 .owner  = THIS_MODULE,
 237         },
 238 };
 239
 240 static __init int ds1742_init(void)
 241 {
 242         return platform_driver_register(&ds1742_rtc_driver);
 243 }
 244
 245 static __exit void ds1742_exit(void)
 246 {
 247         platform_driver_unregister(&ds1742_rtc_driver);
 248 }
 249
 250 module_init(ds1742_init);
 251 module_exit(ds1742_exit);
 252
 253 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 254 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 255 MODULE_LICENSE("GPL");
 256 MODULE_VERSION(DRV_VERSION);
 257 MODULE_ALIAS("platform:rtc-ds1742");