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/platform_data/rtc-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 static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
  43 {
  44         unsigned char reg;
  45         struct platform_device *pdev = to_platform_device(dev);
  46         struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
  47
  48         reg = ops->readbyte(M48T86_REG_B);
  49
  50         if (reg & M48T86_REG_B_DM) {
  51                 /* data (binary) mode */
  52                 tm->tm_sec      = ops->readbyte(M48T86_REG_SEC);
  53                 tm->tm_min      = ops->readbyte(M48T86_REG_MIN);
  54                 tm->tm_hour     = ops->readbyte(M48T86_REG_HOUR) & 0x3F;
  55                 tm->tm_mday     = ops->readbyte(M48T86_REG_DOM);
  56                 /* tm_mon is 0-11 */
  57                 tm->tm_mon      = ops->readbyte(M48T86_REG_MONTH) - 1;
  58                 tm->tm_year     = ops->readbyte(M48T86_REG_YEAR) + 100;
  59                 tm->tm_wday     = ops->readbyte(M48T86_REG_DOW);
  60         } else {
  61                 /* bcd mode */
  62                 tm->tm_sec      = bcd2bin(ops->readbyte(M48T86_REG_SEC));
  63                 tm->tm_min      = bcd2bin(ops->readbyte(M48T86_REG_MIN));
  64                 tm->tm_hour     = bcd2bin(ops->readbyte(M48T86_REG_HOUR) & 0x3F);
  65                 tm->tm_mday     = bcd2bin(ops->readbyte(M48T86_REG_DOM));
  66                 /* tm_mon is 0-11 */
  67                 tm->tm_mon      = bcd2bin(ops->readbyte(M48T86_REG_MONTH)) - 1;
  68                 tm->tm_year     = bcd2bin(ops->readbyte(M48T86_REG_YEAR)) + 100;
  69                 tm->tm_wday     = bcd2bin(ops->readbyte(M48T86_REG_DOW));
  70         }
  71
  72         /* correct the hour if the clock is in 12h mode */
  73         if (!(reg & M48T86_REG_B_H24))
  74                 if (ops->readbyte(M48T86_REG_HOUR) & 0x80)
  75                         tm->tm_hour += 12;
  76
  77         return rtc_valid_tm(tm);
  78 }
  79
  80 static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
  81 {
  82         unsigned char reg;
  83         struct platform_device *pdev = to_platform_device(dev);
  84         struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
  85
  86         reg = ops->readbyte(M48T86_REG_B);
  87
  88         /* update flag and 24h mode */
  89         reg |= M48T86_REG_B_SET | M48T86_REG_B_H24;
  90         ops->writebyte(reg, M48T86_REG_B);
  91
  92         if (reg & M48T86_REG_B_DM) {
  93                 /* data (binary) mode */
  94                 ops->writebyte(tm->tm_sec, M48T86_REG_SEC);
  95                 ops->writebyte(tm->tm_min, M48T86_REG_MIN);
  96                 ops->writebyte(tm->tm_hour, M48T86_REG_HOUR);
  97                 ops->writebyte(tm->tm_mday, M48T86_REG_DOM);
  98                 ops->writebyte(tm->tm_mon + 1, M48T86_REG_MONTH);
  99                 ops->writebyte(tm->tm_year % 100, M48T86_REG_YEAR);
 100                 ops->writebyte(tm->tm_wday, M48T86_REG_DOW);
 101         } else {
 102                 /* bcd mode */
 103                 ops->writebyte(bin2bcd(tm->tm_sec), M48T86_REG_SEC);
 104                 ops->writebyte(bin2bcd(tm->tm_min), M48T86_REG_MIN);
 105                 ops->writebyte(bin2bcd(tm->tm_hour), M48T86_REG_HOUR);
 106                 ops->writebyte(bin2bcd(tm->tm_mday), M48T86_REG_DOM);
 107                 ops->writebyte(bin2bcd(tm->tm_mon + 1), M48T86_REG_MONTH);
 108                 ops->writebyte(bin2bcd(tm->tm_year % 100), M48T86_REG_YEAR);
 109                 ops->writebyte(bin2bcd(tm->tm_wday), M48T86_REG_DOW);
 110         }
 111
 112         /* update ended */
 113         reg &= ~M48T86_REG_B_SET;
 114         ops->writebyte(reg, M48T86_REG_B);
 115
 116         return 0;
 117 }
 118
 119 static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
 120 {
 121         unsigned char reg;
 122         struct platform_device *pdev = to_platform_device(dev);
 123         struct m48t86_ops *ops = dev_get_platdata(&pdev->dev);
 124
 125         reg = ops->readbyte(M48T86_REG_B);
 126
 127         seq_printf(seq, "mode\t\t: %s\n",
 128                  (reg & M48T86_REG_B_DM) ? "binary" : "bcd");
 129
 130         reg = ops->readbyte(M48T86_REG_D);
 131
 132         seq_printf(seq, "battery\t\t: %s\n",
 133                  (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
 134
 135         return 0;
 136 }
 137
 138 static const struct rtc_class_ops m48t86_rtc_ops = {
 139         .read_time      = m48t86_rtc_read_time,
 140         .set_time       = m48t86_rtc_set_time,
 141         .proc           = m48t86_rtc_proc,
 142 };
 143
 144 static int m48t86_rtc_probe(struct platform_device *dev)
 145 {
 146         unsigned char reg;
 147         struct m48t86_ops *ops = dev_get_platdata(&dev->dev);
 148         struct rtc_device *rtc;
 149
 150         rtc = devm_rtc_device_register(&dev->dev, "m48t86",
 151                                 &m48t86_rtc_ops, THIS_MODULE);
 152
 153         if (IS_ERR(rtc))
 154                 return PTR_ERR(rtc);
 155
 156         platform_set_drvdata(dev, rtc);
 157
 158         /* read battery status */
 159         reg = ops->readbyte(M48T86_REG_D);
 160         dev_info(&dev->dev, "battery %s\n",
 161                 (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
 162
 163         return 0;
 164 }
 165
 166 static struct platform_driver m48t86_rtc_platform_driver = {
 167         .driver         = {
 168                 .name   = "rtc-m48t86",
 169         },
 170         .probe          = m48t86_rtc_probe,
 171 };
 172
 173 module_platform_driver(m48t86_rtc_platform_driver);
 174
 175 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 176 MODULE_DESCRIPTION("M48T86 RTC driver");
 177 MODULE_LICENSE("GPL");
 178 MODULE_ALIAS("platform:rtc-m48t86");