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