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/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
  25 #define DRV_VERSION "0.4"
  26
  27 #define RTC_SIZE                8
  28
  29 #define RTC_CONTROL             0
  30 #define RTC_CENTURY             0
  31 #define RTC_SECONDS             1
  32 #define RTC_MINUTES             2
  33 #define RTC_HOURS               3
  34 #define RTC_DAY                 4
  35 #define RTC_DATE                5
  36 #define RTC_MONTH               6
  37 #define RTC_YEAR                7
  38
  39 #define RTC_CENTURY_MASK        0x3f
  40 #define RTC_SECONDS_MASK        0x7f
  41 #define RTC_DAY_MASK            0x07
  42
  43 /* Bits in the Control/Century register */
  44 #define RTC_WRITE               0x80
  45 #define RTC_READ                0x40
  46
  47 /* Bits in the Seconds register */
  48 #define RTC_STOP                0x80
  49
  50 /* Bits in the Day register */
  51 #define RTC_BATT_FLAG           0x80
  52
  53 struct rtc_plat_data {
  54         struct rtc_device *rtc;
  55         void __iomem *ioaddr_nvram;
  56         void __iomem *ioaddr_rtc;
  57         size_t size_nvram;
  58         size_t size;
  59         unsigned long last_jiffies;
  60         struct bin_attribute nvram_attr;
  61 };
  62
  63 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
  64 {
  65         struct platform_device *pdev = to_platform_device(dev);
  66         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  67         void __iomem *ioaddr = pdata->ioaddr_rtc;
  68         u8 century;
  69
  70         century = bin2bcd((tm->tm_year + 1900) / 100);
  71
  72         writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
  73
  74         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  75         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  76         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  77         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  78         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  79         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  80         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  81
  82         /* RTC_CENTURY and RTC_CONTROL share same register */
  83         writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
  84         writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  85         return 0;
  86 }
  87
  88 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
  89 {
  90         struct platform_device *pdev = to_platform_device(dev);
  91         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  92         void __iomem *ioaddr = pdata->ioaddr_rtc;
  93         unsigned int year, month, day, hour, minute, second, week;
  94         unsigned int century;
  95
  96         /* give enough time to update RTC in case of continuous read */
  97         if (pdata->last_jiffies == jiffies)
  98                 msleep(1);
  99         pdata->last_jiffies = jiffies;
 100         writeb(RTC_READ, ioaddr + RTC_CONTROL);
 101         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 102         minute = readb(ioaddr + RTC_MINUTES);
 103         hour = readb(ioaddr + RTC_HOURS);
 104         day = readb(ioaddr + RTC_DATE);
 105         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 106         month = readb(ioaddr + RTC_MONTH);
 107         year = readb(ioaddr + RTC_YEAR);
 108         century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 109         writeb(0, ioaddr + RTC_CONTROL);
 110         tm->tm_sec = bcd2bin(second);
 111         tm->tm_min = bcd2bin(minute);
 112         tm->tm_hour = bcd2bin(hour);
 113         tm->tm_mday = bcd2bin(day);
 114         tm->tm_wday = bcd2bin(week);
 115         tm->tm_mon = bcd2bin(month) - 1;
 116         /* year is 1900 + tm->tm_year */
 117         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 118
 119         if (rtc_valid_tm(tm) < 0) {
 120                 dev_err(dev, "retrieved date/time is not valid.\n");
 121                 rtc_time_to_tm(0, tm);
 122         }
 123         return 0;
 124 }
 125
 126 static const struct rtc_class_ops ds1742_rtc_ops = {
 127         .read_time      = ds1742_rtc_read_time,
 128         .set_time       = ds1742_rtc_set_time,
 129 };
 130
 131 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
 132                                  struct bin_attribute *bin_attr,
 133                                  char *buf, loff_t pos, size_t size)
 134 {
 135         struct device *dev = container_of(kobj, struct device, kobj);
 136         struct platform_device *pdev = to_platform_device(dev);
 137         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 138         void __iomem *ioaddr = pdata->ioaddr_nvram;
 139         ssize_t count;
 140
 141         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 142                 *buf++ = readb(ioaddr + pos++);
 143         return count;
 144 }
 145
 146 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
 147                                   struct bin_attribute *bin_attr,
 148                                   char *buf, loff_t pos, size_t size)
 149 {
 150         struct device *dev = container_of(kobj, struct device, kobj);
 151         struct platform_device *pdev = to_platform_device(dev);
 152         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 153         void __iomem *ioaddr = pdata->ioaddr_nvram;
 154         ssize_t count;
 155
 156         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 157                 writeb(*buf++, ioaddr + pos++);
 158         return count;
 159 }
 160
 161 static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 162 {
 163         struct rtc_device *rtc;
 164         struct resource *res;
 165         unsigned int cen, sec;
 166         struct rtc_plat_data *pdata;
 167         void __iomem *ioaddr;
 168         int ret = 0;
 169
 170         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 171         if (!res)
 172                 return -ENODEV;
 173         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 174         if (!pdata)
 175                 return -ENOMEM;
 176         pdata->size = resource_size(res);
 177         if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
 178                 pdev->name))
 179                 return -EBUSY;
 180         ioaddr = devm_ioremap(&pdev->dev, res->start, pdata->size);
 181         if (!ioaddr)
 182                 return -ENOMEM;
 183
 184         pdata->ioaddr_nvram = ioaddr;
 185         pdata->size_nvram = pdata->size - RTC_SIZE;
 186         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 187
 188         sysfs_bin_attr_init(&pdata->nvram_attr);
 189         pdata->nvram_attr.attr.name = "nvram";
 190         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 191         pdata->nvram_attr.read = ds1742_nvram_read;
 192         pdata->nvram_attr.write = ds1742_nvram_write;
 193         pdata->nvram_attr.size = pdata->size_nvram;
 194
 195         /* turn RTC on if it was not on */
 196         ioaddr = pdata->ioaddr_rtc;
 197         sec = readb(ioaddr + RTC_SECONDS);
 198         if (sec & RTC_STOP) {
 199                 sec &= RTC_SECONDS_MASK;
 200                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 201                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 202                 writeb(sec, ioaddr + RTC_SECONDS);
 203                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 204         }
 205         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 206                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 207
 208         pdata->last_jiffies = jiffies;
 209         platform_set_drvdata(pdev, pdata);
 210         rtc = rtc_device_register(pdev->name, &pdev->dev,
 211                                   &ds1742_rtc_ops, THIS_MODULE);
 212         if (IS_ERR(rtc))
 213                 return PTR_ERR(rtc);
 214         pdata->rtc = rtc;
 215
 216         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 217         if (ret) {
 218                 dev_err(&pdev->dev, "creating nvram file in sysfs failed\n");
 219                 rtc_device_unregister(rtc);
 220         }
 221         return ret;
 222 }
 223
 224 static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
 225 {
 226         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 227
 228         sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 229         rtc_device_unregister(pdata->rtc);
 230         return 0;
 231 }
 232
 233 static struct platform_driver ds1742_rtc_driver = {
 234         .probe          = ds1742_rtc_probe,
 235         .remove         = __devexit_p(ds1742_rtc_remove),
 236         .driver         = {
 237                 .name   = "rtc-ds1742",
 238                 .owner  = THIS_MODULE,
 239         },
 240 };
 241
 242 static __init int ds1742_init(void)
 243 {
 244         return platform_driver_register(&ds1742_rtc_driver);
 245 }
 246
 247 static __exit void ds1742_exit(void)
 248 {
 249         platform_driver_unregister(&ds1742_rtc_driver);
 250 }
 251
 252 module_init(ds1742_init);
 253 module_exit(ds1742_exit);
 254
 255 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 256 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 257 MODULE_LICENSE("GPL");
 258 MODULE_VERSION(DRV_VERSION);
 259 MODULE_ALIAS("platform:rtc-ds1742");