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 "0.3"
  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
  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 baseaddr;
  59         unsigned long last_jiffies;
  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, char *buf,
 131                                  loff_t pos, size_t size)
 132 {
 133         struct platform_device *pdev =
 134                 to_platform_device(container_of(kobj, struct device, kobj));
 135         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 136         void __iomem *ioaddr = pdata->ioaddr_nvram;
 137         ssize_t count;
 138
 139         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 140                 *buf++ = readb(ioaddr + pos++);
 141         return count;
 142 }
 143
 144 static ssize_t ds1742_nvram_write(struct kobject *kobj, char *buf,
 145                                   loff_t pos, size_t size)
 146 {
 147         struct platform_device *pdev =
 148                 to_platform_device(container_of(kobj, struct device, kobj));
 149         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 150         void __iomem *ioaddr = pdata->ioaddr_nvram;
 151         ssize_t count;
 152
 153         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 154                 writeb(*buf++, ioaddr + pos++);
 155         return count;
 156 }
 157
 158 static struct bin_attribute ds1742_nvram_attr = {
 159         .attr = {
 160                 .name = "nvram",
 161                 .mode = S_IRUGO | S_IWUGO,
 162                 .owner = THIS_MODULE,
 163         },
 164         .read = ds1742_nvram_read,
 165         .write = ds1742_nvram_write,
 166 };
 167
 168 static int __init ds1742_rtc_probe(struct platform_device *pdev)
 169 {
 170         struct rtc_device *rtc;
 171         struct resource *res;
 172         unsigned int cen, sec;
 173         struct rtc_plat_data *pdata = NULL;
 174         void __iomem *ioaddr = NULL;
 175         int ret = 0;
 176
 177         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 178         if (!res)
 179                 return -ENODEV;
 180         pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
 181         if (!pdata)
 182                 return -ENOMEM;
 183         pdata->size = res->end - res->start + 1;
 184         if (!request_mem_region(res->start, pdata->size, pdev->name)) {
 185                 ret = -EBUSY;
 186                 goto out;
 187         }
 188         pdata->baseaddr = res->start;
 189         ioaddr = ioremap(pdata->baseaddr, pdata->size);
 190         if (!ioaddr) {
 191                 ret = -ENOMEM;
 192                 goto out;
 193         }
 194         pdata->ioaddr_nvram = ioaddr;
 195         pdata->size_nvram = pdata->size - RTC_SIZE;
 196         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 197
 198         /* turn RTC on if it was not on */
 199         ioaddr = pdata->ioaddr_rtc;
 200         sec = readb(ioaddr + RTC_SECONDS);
 201         if (sec & RTC_STOP) {
 202                 sec &= RTC_SECONDS_MASK;
 203                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 204                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 205                 writeb(sec, ioaddr + RTC_SECONDS);
 206                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 207         }
 208         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 209                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 210
 211         rtc = rtc_device_register(pdev->name, &pdev->dev,
 212                                   &ds1742_rtc_ops, THIS_MODULE);
 213         if (IS_ERR(rtc)) {
 214                 ret = PTR_ERR(rtc);
 215                 goto out;
 216         }
 217         pdata->rtc = rtc;
 218         pdata->last_jiffies = jiffies;
 219         platform_set_drvdata(pdev, pdata);
 220         ds1742_nvram_attr.size = max(ds1742_nvram_attr.size,
 221                                      pdata->size_nvram);
 222         ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
 223         if (ret)
 224                 goto out;
 225         return 0;
 226  out:
 227         if (pdata->rtc)
 228                 rtc_device_unregister(pdata->rtc);
 229         if (pdata->ioaddr_nvram)
 230                 iounmap(pdata->ioaddr_nvram);
 231         if (pdata->baseaddr)
 232                 release_mem_region(pdata->baseaddr, pdata->size);
 233         kfree(pdata);
 234         return ret;
 235 }
 236
 237 static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
 238 {
 239         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 240
 241         sysfs_remove_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
 242         rtc_device_unregister(pdata->rtc);
 243         iounmap(pdata->ioaddr_nvram);
 244         release_mem_region(pdata->baseaddr, pdata->size);
 245         kfree(pdata);
 246         return 0;
 247 }
 248
 249 static struct platform_driver ds1742_rtc_driver = {
 250         .probe          = ds1742_rtc_probe,
 251         .remove         = __devexit_p(ds1742_rtc_remove),
 252         .driver         = {
 253                 .name   = "ds1742",
 254                 .owner  = THIS_MODULE,
 255         },
 256 };
 257
 258 static __init int ds1742_init(void)
 259 {
 260         return platform_driver_register(&ds1742_rtc_driver);
 261 }
 262
 263 static __exit void ds1742_exit(void)
 264 {
 265         return platform_driver_unregister(&ds1742_rtc_driver);
 266 }
 267
 268 module_init(ds1742_init);
 269 module_exit(ds1742_exit);
 270
 271 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 272 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 273 MODULE_LICENSE("GPL");
 274 MODULE_VERSION(DRV_VERSION);