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 #include <linux/module.h>
  25
  26 #define DRV_VERSION "0.4"
  27
  28 #define RTC_SIZE                8
  29
  30 #define RTC_CONTROL             0
  31 #define RTC_CENTURY             0
  32 #define RTC_SECONDS             1
  33 #define RTC_MINUTES             2
  34 #define RTC_HOURS               3
  35 #define RTC_DAY                 4
  36 #define RTC_DATE                5
  37 #define RTC_MONTH               6
  38 #define RTC_YEAR                7
  39
  40 #define RTC_CENTURY_MASK        0x3f
  41 #define RTC_SECONDS_MASK        0x7f
  42 #define RTC_DAY_MASK            0x07
  43
  44 /* Bits in the Control/Century register */
  45 #define RTC_WRITE               0x80
  46 #define RTC_READ                0x40
  47
  48 /* Bits in the Seconds register */
  49 #define RTC_STOP                0x80
  50
  51 /* Bits in the Day register */
  52 #define RTC_BATT_FLAG           0x80
  53
  54 struct rtc_plat_data {
  55         void __iomem *ioaddr_nvram;
  56         void __iomem *ioaddr_rtc;
  57         size_t size_nvram;
  58         unsigned long last_jiffies;
  59         struct bin_attribute nvram_attr;
  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         return rtc_valid_tm(tm);
 119 }
 120
 121 static const struct rtc_class_ops ds1742_rtc_ops = {
 122         .read_time      = ds1742_rtc_read_time,
 123         .set_time       = ds1742_rtc_set_time,
 124 };
 125
 126 static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,
 127                                  struct bin_attribute *bin_attr,
 128                                  char *buf, loff_t pos, size_t size)
 129 {
 130         struct device *dev = container_of(kobj, struct device, kobj);
 131         struct platform_device *pdev = to_platform_device(dev);
 132         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 133         void __iomem *ioaddr = pdata->ioaddr_nvram;
 134         ssize_t count;
 135
 136         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 137                 *buf++ = readb(ioaddr + pos++);
 138         return count;
 139 }
 140
 141 static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,
 142                                   struct bin_attribute *bin_attr,
 143                                   char *buf, loff_t pos, size_t size)
 144 {
 145         struct device *dev = container_of(kobj, struct device, kobj);
 146         struct platform_device *pdev = to_platform_device(dev);
 147         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 148         void __iomem *ioaddr = pdata->ioaddr_nvram;
 149         ssize_t count;
 150
 151         for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)
 152                 writeb(*buf++, ioaddr + pos++);
 153         return count;
 154 }
 155
 156 static int ds1742_rtc_probe(struct platform_device *pdev)
 157 {
 158         struct rtc_device *rtc;
 159         struct resource *res;
 160         unsigned int cen, sec;
 161         struct rtc_plat_data *pdata;
 162         void __iomem *ioaddr;
 163         int ret = 0;
 164
 165         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 166         if (!pdata)
 167                 return -ENOMEM;
 168
 169         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 170         ioaddr = devm_ioremap_resource(&pdev->dev, res);
 171         if (IS_ERR(ioaddr))
 172                 return PTR_ERR(ioaddr);
 173
 174         pdata->ioaddr_nvram = ioaddr;
 175         pdata->size_nvram = resource_size(res) - RTC_SIZE;
 176         pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 177
 178         sysfs_bin_attr_init(&pdata->nvram_attr);
 179         pdata->nvram_attr.attr.name = "nvram";
 180         pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
 181         pdata->nvram_attr.read = ds1742_nvram_read;
 182         pdata->nvram_attr.write = ds1742_nvram_write;
 183         pdata->nvram_attr.size = pdata->size_nvram;
 184
 185         /* turn RTC on if it was not on */
 186         ioaddr = pdata->ioaddr_rtc;
 187         sec = readb(ioaddr + RTC_SECONDS);
 188         if (sec & RTC_STOP) {
 189                 sec &= RTC_SECONDS_MASK;
 190                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 191                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 192                 writeb(sec, ioaddr + RTC_SECONDS);
 193                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 194         }
 195         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 196                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 197
 198         pdata->last_jiffies = jiffies;
 199         platform_set_drvdata(pdev, pdata);
 200         rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 201                                   &ds1742_rtc_ops, THIS_MODULE);
 202         if (IS_ERR(rtc))
 203                 return PTR_ERR(rtc);
 204
 205         ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 206
 207         return ret;
 208 }
 209
 210 static int ds1742_rtc_remove(struct platform_device *pdev)
 211 {
 212         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 213
 214         sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 215         return 0;
 216 }
 217
 218 static struct platform_driver ds1742_rtc_driver = {
 219         .probe          = ds1742_rtc_probe,
 220         .remove         = ds1742_rtc_remove,
 221         .driver         = {
 222                 .name   = "rtc-ds1742",
 223                 .owner  = THIS_MODULE,
 224         },
 225 };
 226
 227 module_platform_driver(ds1742_rtc_driver);
 228
 229 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 230 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 231 MODULE_LICENSE("GPL");
 232 MODULE_VERSION(DRV_VERSION);
 233 MODULE_ALIAS("platform:rtc-ds1742");