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