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 DRV_VERSION "0.4"
  28
  29 #define RTC_SIZE                8
  30
  31 #define RTC_CONTROL             0
  32 #define RTC_CENTURY             0
  33 #define RTC_SECONDS             1
  34 #define RTC_MINUTES             2
  35 #define RTC_HOURS               3
  36 #define RTC_DAY                 4
  37 #define RTC_DATE                5
  38 #define RTC_MONTH               6
  39 #define RTC_YEAR                7
  40
  41 #define RTC_CENTURY_MASK        0x3f
  42 #define RTC_SECONDS_MASK        0x7f
  43 #define RTC_DAY_MASK            0x07
  44
  45 /* Bits in the Control/Century register */
  46 #define RTC_WRITE               0x80
  47 #define RTC_READ                0x40
  48
  49 /* Bits in the Seconds register */
  50 #define RTC_STOP                0x80
  51
  52 /* Bits in the Day register */
  53 #define RTC_BATT_FLAG           0x80
  54
  55 struct rtc_plat_data {
  56         void __iomem *ioaddr_nvram;
  57         void __iomem *ioaddr_rtc;
  58         size_t size_nvram;
  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         return rtc_valid_tm(tm);
 120 }
 121
 122 static const struct rtc_class_ops ds1742_rtc_ops = {
 123         .read_time      = ds1742_rtc_read_time,
 124         .set_time       = ds1742_rtc_set_time,
 125 };
 126
 127 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
 128                                  struct bin_attribute *bin_attr,
 129                                  char *buf, loff_t pos, size_t size)
 130 {
 131         struct device *dev = container_of(kobj, struct device, kobj);
 132         struct platform_device *pdev = to_platform_device(dev);
 133         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 134         void __iomem *ioaddr = pdata->ioaddr_nvram;
 135         ssize_t count;
 136
 137         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 138                 *buf++ = readb(ioaddr + pos++);
 139         return count;
 140 }
 141
 142 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
 143                                   struct bin_attribute *bin_attr,
 144                                   char *buf, loff_t pos, size_t size)
 145 {
 146         struct device *dev = container_of(kobj, struct device, kobj);
 147         struct platform_device *pdev = to_platform_device(dev);
 148         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 149         void __iomem *ioaddr = pdata->ioaddr_nvram;
 150         ssize_t count;
 151
 152         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 153                 writeb(*buf++, ioaddr + pos++);
 154         return count;
 155 }
 156
 157 static int ds1742_rtc_probe(struct platform_device *pdev)
 158 {
 159         struct rtc_device *rtc;
 160         struct resource *res;
 161         unsigned int cen, sec;
 162         struct rtc_plat_data *pdata;
 163         void __iomem *ioaddr;
 164         int ret = 0;
 165
 166         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 167         if (!pdata)
 168                 return -ENOMEM;
 169
 170         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 171         ioaddr = devm_ioremap_resource(&pdev->dev, res);
 172         if (IS_ERR(ioaddr))
 173                 return PTR_ERR(ioaddr);
 174
 175         pdata->ioaddr_nvram = ioaddr;
 176         pdata->size_nvram = resource_size(res) - RTC_SIZE;
 177         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 178
 179         sysfs_bin_attr_init(&pdata->nvram_attr);
 180         pdata->nvram_attr.attr.name = "nvram";
 181         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 182         pdata->nvram_attr.read = ds1742_nvram_read;
 183         pdata->nvram_attr.write = ds1742_nvram_write;
 184         pdata->nvram_attr.size = pdata->size_nvram;
 185
 186         /* turn RTC on if it was not on */
 187         ioaddr = pdata->ioaddr_rtc;
 188         sec = readb(ioaddr + RTC_SECONDS);
 189         if (sec & RTC_STOP) {
 190                 sec &= RTC_SECONDS_MASK;
 191                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 192                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 193                 writeb(sec, ioaddr + RTC_SECONDS);
 194                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 195         }
 196         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 197                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 198
 199         pdata->last_jiffies = jiffies;
 200         platform_set_drvdata(pdev, pdata);
 201         rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 202                                   &ds1742_rtc_ops, THIS_MODULE);
 203         if (IS_ERR(rtc))
 204                 return PTR_ERR(rtc);
 205
 206         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 207
 208         return ret;
 209 }
 210
 211 static int ds1742_rtc_remove(struct platform_device *pdev)
 212 {
 213         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 214
 215         sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 216         return 0;
 217 }
 218
 219 static struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
 220         { .compatible = "maxim,ds1742", },
 221         { }
 222 };
 223 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
 224
 225 static struct platform_driver ds1742_rtc_driver = {
 226         .probe          = ds1742_rtc_probe,
 227         .remove         = ds1742_rtc_remove,
 228         .driver         = {
 229                 .name   = "rtc-ds1742",
 230                 .owner  = THIS_MODULE,
 231                 .of_match_table = 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_VERSION(DRV_VERSION);
 241 MODULE_ALIAS("platform:rtc-ds1742");