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/kernel.h>
  17 #include <linux/gfp.h>
  18 #include <linux/delay.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/rtc.h>
  21 #include <linux/of.h>
  22 #include <linux/of_device.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/io.h>
  25 #include <linux/module.h>
  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         void __iomem *ioaddr_nvram;
  55         void __iomem *ioaddr_rtc;
  56         size_t size_nvram;
  57         unsigned long last_jiffies;
  58         struct bin_attribute nvram_attr;
  59 };
  60
  61 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
  62 {
  63         struct platform_device *pdev = to_platform_device(dev);
  64         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  65         void __iomem *ioaddr = pdata->ioaddr_rtc;
  66         u8 century;
  67
  68         century = bin2bcd((tm->tm_year + 1900) / 100);
  69
  70         writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
  71
  72         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  73         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  74         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  75         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  76         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  77         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  78         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  79
  80         /* RTC_CENTURY and RTC_CONTROL share same register */
  81         writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
  82         writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  83         return 0;
  84 }
  85
  86 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
  87 {
  88         struct platform_device *pdev = to_platform_device(dev);
  89         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  90         void __iomem *ioaddr = pdata->ioaddr_rtc;
  91         unsigned int year, month, day, hour, minute, second, week;
  92         unsigned int century;
  93
  94         /* give enough time to update RTC in case of continuous read */
  95         if (pdata->last_jiffies == jiffies)
  96                 msleep(1);
  97         pdata->last_jiffies = jiffies;
  98         writeb(RTC_READ, ioaddr + RTC_CONTROL);
  99         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
 100         minute = readb(ioaddr + RTC_MINUTES);
 101         hour = readb(ioaddr + RTC_HOURS);
 102         day = readb(ioaddr + RTC_DATE);
 103         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 104         month = readb(ioaddr + RTC_MONTH);
 105         year = readb(ioaddr + RTC_YEAR);
 106         century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 107         writeb(0, ioaddr + RTC_CONTROL);
 108         tm->tm_sec = bcd2bin(second);
 109         tm->tm_min = bcd2bin(minute);
 110         tm->tm_hour = bcd2bin(hour);
 111         tm->tm_mday = bcd2bin(day);
 112         tm->tm_wday = bcd2bin(week);
 113         tm->tm_mon = bcd2bin(month) - 1;
 114         /* year is 1900 + tm->tm_year */
 115         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 116
 117         return rtc_valid_tm(tm);
 118 }
 119
 120 static const struct rtc_class_ops ds1742_rtc_ops = {
 121         .read_time      = ds1742_rtc_read_time,
 122         .set_time       = ds1742_rtc_set_time,
 123 };
 124
 125 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
 126                                  struct bin_attribute *bin_attr,
 127                                  char *buf, loff_t pos, size_t size)
 128 {
 129         struct device *dev = container_of(kobj, struct device, kobj);
 130         struct platform_device *pdev = to_platform_device(dev);
 131         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 132         void __iomem *ioaddr = pdata->ioaddr_nvram;
 133         ssize_t count;
 134
 135         for (count = 0; count < size; count++)
 136                 *buf++ = readb(ioaddr + pos++);
 137         return count;
 138 }
 139
 140 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
 141                                   struct bin_attribute *bin_attr,
 142                                   char *buf, loff_t pos, size_t size)
 143 {
 144         struct device *dev = container_of(kobj, struct device, kobj);
 145         struct platform_device *pdev = to_platform_device(dev);
 146         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 147         void __iomem *ioaddr = pdata->ioaddr_nvram;
 148         ssize_t count;
 149
 150         for (count = 0; count < size; count++)
 151                 writeb(*buf++, ioaddr + pos++);
 152         return count;
 153 }
 154
 155 static int ds1742_rtc_probe(struct platform_device *pdev)
 156 {
 157         struct rtc_device *rtc;
 158         struct resource *res;
 159         unsigned int cen, sec;
 160         struct rtc_plat_data *pdata;
 161         void __iomem *ioaddr;
 162         int ret = 0;
 163
 164         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 165         if (!pdata)
 166                 return -ENOMEM;
 167
 168         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 169         ioaddr = devm_ioremap_resource(&pdev->dev, res);
 170         if (IS_ERR(ioaddr))
 171                 return PTR_ERR(ioaddr);
 172
 173         pdata->ioaddr_nvram = ioaddr;
 174         pdata->size_nvram = resource_size(res) - RTC_SIZE;
 175         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 176
 177         sysfs_bin_attr_init(&pdata->nvram_attr);
 178         pdata->nvram_attr.attr.name = "nvram";
 179         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 180         pdata->nvram_attr.read = ds1742_nvram_read;
 181         pdata->nvram_attr.write = ds1742_nvram_write;
 182         pdata->nvram_attr.size = pdata->size_nvram;
 183
 184         /* turn RTC on if it was not on */
 185         ioaddr = pdata->ioaddr_rtc;
 186         sec = readb(ioaddr + RTC_SECONDS);
 187         if (sec & RTC_STOP) {
 188                 sec &= RTC_SECONDS_MASK;
 189                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 190                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 191                 writeb(sec, ioaddr + RTC_SECONDS);
 192                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 193         }
 194         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 195                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 196
 197         pdata->last_jiffies = jiffies;
 198         platform_set_drvdata(pdev, pdata);
 199         rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 200                                   &ds1742_rtc_ops, THIS_MODULE);
 201         if (IS_ERR(rtc))
 202                 return PTR_ERR(rtc);
 203
 204         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 205         if (ret)
 206                 dev_err(&pdev->dev, "Unable to create sysfs entry: %s\n",
 207                         pdata->nvram_attr.attr.name);
 208
 209         return 0;
 210 }
 211
 212 static int ds1742_rtc_remove(struct platform_device *pdev)
 213 {
 214         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 215
 216         sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 217         return 0;
 218 }
 219
 220 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
 221         { .compatible = "maxim,ds1742", },
 222         { }
 223 };
 224 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
 225
 226 static struct platform_driver ds1742_rtc_driver = {
 227         .probe          = ds1742_rtc_probe,
 228         .remove         = ds1742_rtc_remove,
 229         .driver         = {
 230                 .name   = "rtc-ds1742",
 231                 .of_match_table = of_match_ptr(ds1742_rtc_of_match),
 232         },
 233 };
 234
 235 module_platform_driver(ds1742_rtc_driver);
 236
 237 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 238 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 239 MODULE_LICENSE("GPL");
 240 MODULE_ALIAS("platform:rtc-ds1742");