drivers/rtc/rtc-m48t86.c

   1 /*
   2  * ST M48T86 / Dallas DS12887 RTC driver
   3  * Copyright (c) 2006 Tower Technologies
   4  *
   5  * Author: Alessandro Zummo <a.zummo@towertech.it>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This drivers only supports the clock running in BCD and 24H mode.
  12  * If it will be ever adapted to binary and 12H mode, care must be taken
  13  * to not introduce bugs.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/rtc.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/m48t86.h>
  20 #include <linux/bcd.h>
  21
  22 #define M48T86_REG_SEC          0x00
  23 #define M48T86_REG_SECALRM      0x01
  24 #define M48T86_REG_MIN          0x02
  25 #define M48T86_REG_MINALRM      0x03
  26 #define M48T86_REG_HOUR         0x04
  27 #define M48T86_REG_HOURALRM     0x05
  28 #define M48T86_REG_DOW          0x06 /* 1 = sunday */
  29 #define M48T86_REG_DOM          0x07
  30 #define M48T86_REG_MONTH        0x08 /* 1 - 12 */
  31 #define M48T86_REG_YEAR         0x09 /* 0 - 99 */
  32 #define M48T86_REG_A            0x0A
  33 #define M48T86_REG_B            0x0B
  34 #define M48T86_REG_C            0x0C
  35 #define M48T86_REG_D            0x0D
  36
  37 #define M48T86_REG_B_H24        (1 << 1)
  38 #define M48T86_REG_B_DM         (1 << 2)
  39 #define M48T86_REG_B_SET        (1 << 7)
  40 #define M48T86_REG_D_VRT        (1 << 7)
  41
  42 #define DRV_VERSION "0.1"
  43
  44
  45 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
  46 {
  47         unsigned char reg;
  48         struct platform_device *pdev = to_platform_device(dev);
  49         struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
  50
  51         reg = ops->readbyte(M48T86_REG_B);
  52
  53         if (reg & M48T86_REG_B_DM) {
  54                 /* data (binary) mode */
  55                 tm->tm_sec      = ops->readbyte(M48T86_REG_SEC);
  56                 tm->tm_min      = ops->readbyte(M48T86_REG_MIN);
  57                 tm->tm_hour     = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
  58                 tm->tm_mday     = ops->readbyte(M48T86_REG_DOM);
  59                 /* tm_mon is 0-11 */
  60                 tm->tm_mon      = ops->readbyte(M48T86_REG_MONTH) - 1;
  61                 tm->tm_year     = ops->readbyte(M48T86_REG_YEAR) + 100;
  62                 tm->tm_wday     = ops->readbyte(M48T86_REG_DOW);
  63         } else {
  64                 /* bcd mode */
  65                 tm->tm_sec      = bcd2bin(ops->readbyte(M48T86_REG_SEC));
  66                 tm->tm_min      = bcd2bin(ops->readbyte(M48T86_REG_MIN));
  67                 tm->tm_hour     = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
  68                 tm->tm_mday     = bcd2bin(ops->readbyte(M48T86_REG_DOM));
  69                 /* tm_mon is 0-11 */
  70                 tm->tm_mon      = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
  71                 tm->tm_year     = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
  72                 tm->tm_wday     = bcd2bin(ops->readbyte(M48T86_REG_DOW));
  73         }
  74
  75         /* correct the hour if the clock is in 12h mode */
  76         if (!(reg & M48T86_REG_B_H24))
  77                 if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
  78                         tm->tm_hour += 12;
  79
  80         return rtc_valid_tm(tm);
  81 }
  82
  83 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
  84 {
  85         unsigned char reg;
  86         struct platform_device *pdev = to_platform_device(dev);
  87         struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
  88
  89         reg = ops->readbyte(M48T86_REG_B);
  90
  91         /* update flag and 24h mode */
  92         reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
  93         ops->writebyte(reg, M48T86_REG_B);
  94
  95         if (reg & M48T86_REG_B_DM) {
  96                 /* data (binary) mode */
  97                 ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
  98                 ops->writebyte(tm->tm_min, M48T86_REG_MIN);
  99                 ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
 100                 ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
 101                 ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
 102                 ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
 103                 ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
 104         } else {
 105                 /* bcd mode */
 106                 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
 107                 ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
 108                 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
 109                 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
 110                 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
 111                 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
 112                 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
 113         }
 114
 115         /* update ended */
 116         reg &= ~M48T86_REG_B_SET;
 117         ops->writebyte(reg, M48T86_REG_B);
 118
 119         return 0;
 120 }
 121
 122 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
 123 {
 124         unsigned char reg;
 125         struct platform_device *pdev = to_platform_device(dev);
 126         struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
 127
 128         reg = ops->readbyte(M48T86_REG_B);
 129
 130         seq_printf(seq, "mode\t\t: %s\n",
 131                  (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
 132
 133         reg = ops->readbyte(M48T86_REG_D);
 134
 135         seq_printf(seq, "battery\t\t: %s\n",
 136                  (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
 137
 138         return 0;
 139 }
 140
 141 static const struct rtc_class_ops m48t86_rtc_ops = {
 142         .read_time      = m48t86_rtc_read_time,
 143         .set_time       = m48t86_rtc_set_time,
 144         .proc           = m48t86_rtc_proc,
 145 };
 146
 147 static int m48t86_rtc_probe(struct platform_device *dev)
 148 {
 149         unsigned char reg;
 150         struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
 151         struct rtc_device *rtc;
 152
 153         rtc = devm_rtc_device_register(&dev->dev, "m48t86",
 154                                 &m48t86_rtc_ops, THIS_MODULE);
 155
 156         if (IS_ERR(rtc))
 157                 return PTR_ERR(rtc);
 158
 159         platform_set_drvdata(dev, rtc);
 160
 161         /* read battery status */
 162         reg = ops->readbyte(M48T86_REG_D);
 163         dev_info(&dev->dev, "battery %s\n",
 164                 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
 165
 166         return 0;
 167 }
 168
 169 static struct platform_driver m48t86_rtc_platform_driver = {
 170         .driver         = {
 171                 .name   = "rtc-m48t86",
 172         },
 173         .probe          = m48t86_rtc_probe,
 174 };
 175
 176 module_platform_driver(m48t86_rtc_platform_driver);
 177
 178 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 179 MODULE_DESCRIPTION("M48T86 RTC driver");
 180 MODULE_LICENSE("GPL");
 181 MODULE_VERSION(DRV_VERSION);
 182 MODULE_ALIAS("platform:rtc-m48t86");