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         unsigned long last_jiffies;
  57 };
  58
  59 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
  60 {
  61         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
  62         void __iomem *ioaddr = pdata->ioaddr_rtc;
  63         u8 century;
  64
  65         century = bin2bcd((tm->tm_year + 1900) / 100);
  66
  67         writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
  68
  69         writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  70         writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  71         writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  72         writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  73         writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  74         writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  75         writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
  76
  77         /* RTC_CENTURY and RTC_CONTROL share same register */
  78         writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
  79         writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  80         return 0;
  81 }
  82
  83 static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
  84 {
  85         struct rtc_plat_data *pdata = dev_get_drvdata(dev);
  86         void __iomem *ioaddr = pdata->ioaddr_rtc;
  87         unsigned int year, month, day, hour, minute, second, week;
  88         unsigned int century;
  89
  90         /* give enough time to update RTC in case of continuous read */
  91         if (pdata->last_jiffies == jiffies)
  92                 msleep(1);
  93         pdata->last_jiffies = jiffies;
  94         writeb(RTC_READ, ioaddr + RTC_CONTROL);
  95         second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
  96         minute = readb(ioaddr + RTC_MINUTES);
  97         hour = readb(ioaddr + RTC_HOURS);
  98         day = readb(ioaddr + RTC_DATE);
  99         week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
 100         month = readb(ioaddr + RTC_MONTH);
 101         year = readb(ioaddr + RTC_YEAR);
 102         century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 103         writeb(0, ioaddr + RTC_CONTROL);
 104         tm->tm_sec = bcd2bin(second);
 105         tm->tm_min = bcd2bin(minute);
 106         tm->tm_hour = bcd2bin(hour);
 107         tm->tm_mday = bcd2bin(day);
 108         tm->tm_wday = bcd2bin(week);
 109         tm->tm_mon = bcd2bin(month) - 1;
 110         /* year is 1900 + tm->tm_year */
 111         tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
 112
 113         return 0;
 114 }
 115
 116 static const struct rtc_class_ops ds1742_rtc_ops = {
 117         .read_time      = ds1742_rtc_read_time,
 118         .set_time       = ds1742_rtc_set_time,
 119 };
 120
 121 static int ds1742_nvram_read(void *priv, unsigned int pos, void *val,
 122                              size_t bytes)
 123 {
 124         struct rtc_plat_data *pdata = priv;
 125         void __iomem *ioaddr = pdata->ioaddr_nvram;
 126         u8 *buf = val;
 127
 128         for (; bytes; bytes--)
 129                 *buf++ = readb(ioaddr + pos++);
 130         return 0;
 131 }
 132
 133 static int ds1742_nvram_write(void *priv, unsigned int pos, void *val,
 134                               size_t bytes)
 135 {
 136         struct rtc_plat_data *pdata = priv;
 137         void __iomem *ioaddr = pdata->ioaddr_nvram;
 138         u8 *buf = val;
 139
 140         for (; bytes; bytes--)
 141                 writeb(*buf++, ioaddr + pos++);
 142         return 0;
 143 }
 144
 145 static int ds1742_rtc_probe(struct platform_device *pdev)
 146 {
 147         struct rtc_device *rtc;
 148         struct resource *res;
 149         unsigned int cen, sec;
 150         struct rtc_plat_data *pdata;
 151         void __iomem *ioaddr;
 152         int ret = 0;
 153         struct nvmem_config nvmem_cfg = {
 154                 .name = "ds1742_nvram",
 155                 .reg_read = ds1742_nvram_read,
 156                 .reg_write = ds1742_nvram_write,
 157         };
 158
 159
 160         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 161         if (!pdata)
 162                 return -ENOMEM;
 163
 164         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 165         ioaddr = devm_ioremap_resource(&pdev->dev, res);
 166         if (IS_ERR(ioaddr))
 167                 return PTR_ERR(ioaddr);
 168
 169         pdata->ioaddr_nvram = ioaddr;
 170         pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE;
 171
 172         nvmem_cfg.size = resource_size(res) - RTC_SIZE;
 173         nvmem_cfg.priv = pdata;
 174
 175         /* turn RTC on if it was not on */
 176         ioaddr = pdata->ioaddr_rtc;
 177         sec = readb(ioaddr + RTC_SECONDS);
 178         if (sec & RTC_STOP) {
 179                 sec &= RTC_SECONDS_MASK;
 180                 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
 181                 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
 182                 writeb(sec, ioaddr + RTC_SECONDS);
 183                 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
 184         }
 185         if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
 186                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 187
 188         pdata->last_jiffies = jiffies;
 189         platform_set_drvdata(pdev, pdata);
 190
 191         rtc = devm_rtc_allocate_device(&pdev->dev);
 192         if (IS_ERR(rtc))
 193                 return PTR_ERR(rtc);
 194
 195         rtc->ops = &ds1742_rtc_ops;
 196         rtc->nvram_old_abi = true;
 197
 198         ret = rtc_register_device(rtc);
 199         if (ret)
 200                 return ret;
 201
 202         if (rtc_nvmem_register(rtc, &nvmem_cfg))
 203                 dev_err(&pdev->dev, "Unable to register nvmem\n");
 204
 205         return 0;
 206 }
 207
 208 static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
 209         { .compatible = "maxim,ds1742", },
 210         { }
 211 };
 212 MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
 213
 214 static struct platform_driver ds1742_rtc_driver = {
 215         .probe          = ds1742_rtc_probe,
 216         .driver         = {
 217                 .name   = "rtc-ds1742",
 218                 .of_match_table = of_match_ptr(ds1742_rtc_of_match),
 219         },
 220 };
 221
 222 module_platform_driver(ds1742_rtc_driver);
 223
 224 MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
 225 MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
 226 MODULE_LICENSE("GPL");
 227 MODULE_ALIAS("platform:rtc-ds1742");