linux/drivers/rtc/rtc-m48t86.c
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   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
  45static 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 = pdev->dev.platform_data;
  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
  83static 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 = pdev->dev.platform_data;
  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
 122static 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 = pdev->dev.platform_data;
 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
 141static 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
 147static int m48t86_rtc_probe(struct platform_device *dev)
 148{
 149        unsigned char reg;
 150        struct m48t86_ops *ops = dev->dev.platform_data;
 151        struct rtc_device *rtc = rtc_device_register("m48t86",
 152                                &dev->dev, &m48t86_rtc_ops, THIS_MODULE);
 153
 154        if (IS_ERR(rtc))
 155                return PTR_ERR(rtc);
 156
 157        platform_set_drvdata(dev, rtc);
 158
 159        /* read battery status */
 160        reg = ops->readbyte(M48T86_REG_D);
 161        dev_info(&dev->dev, "battery %s\n",
 162                (reg & M48T86_REG_D_VRT) ? "ok" : "exhausted");
 163
 164        return 0;
 165}
 166
 167static int m48t86_rtc_remove(struct platform_device *dev)
 168{
 169        struct rtc_device *rtc = platform_get_drvdata(dev);
 170
 171        if (rtc)
 172                rtc_device_unregister(rtc);
 173
 174        platform_set_drvdata(dev, NULL);
 175
 176        return 0;
 177}
 178
 179static struct platform_driver m48t86_rtc_platform_driver = {
 180        .driver         = {
 181                .name   = "rtc-m48t86",
 182                .owner  = THIS_MODULE,
 183        },
 184        .probe          = m48t86_rtc_probe,
 185        .remove         = m48t86_rtc_remove,
 186};
 187
 188module_platform_driver(m48t86_rtc_platform_driver);
 189
 190MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 191MODULE_DESCRIPTION("M48T86 RTC driver");
 192MODULE_LICENSE("GPL");
 193MODULE_VERSION(DRV_VERSION);
 194MODULE_ALIAS("platform:rtc-m48t86");
 195
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