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