drivers/rtc/rtc-em3027.c

   1 /*
   2  * An rtc/i2c driver for the EM Microelectronic EM3027
   3  * Copyright 2011 CompuLab, Ltd.
   4  *
   5  * Author: Mike Rapoport <mike@compulab.co.il>
   6  *
   7  * Based on rtc-ds1672.c by Alessandro Zummo <a.zummo@towertech.it>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/i2c.h>
  15 #include <linux/rtc.h>
  16 #include <linux/bcd.h>
  17 #include <linux/module.h>
  18
  19 /* Registers */
  20 #define EM3027_REG_ON_OFF_CTRL  0x00
  21 #define EM3027_REG_IRQ_CTRL     0x01
  22 #define EM3027_REG_IRQ_FLAGS    0x02
  23 #define EM3027_REG_STATUS       0x03
  24 #define EM3027_REG_RST_CTRL     0x04
  25
  26 #define EM3027_REG_WATCH_SEC    0x08
  27 #define EM3027_REG_WATCH_MIN    0x09
  28 #define EM3027_REG_WATCH_HOUR   0x0a
  29 #define EM3027_REG_WATCH_DATE   0x0b
  30 #define EM3027_REG_WATCH_DAY    0x0c
  31 #define EM3027_REG_WATCH_MON    0x0d
  32 #define EM3027_REG_WATCH_YEAR   0x0e
  33
  34 #define EM3027_REG_ALARM_SEC    0x10
  35 #define EM3027_REG_ALARM_MIN    0x11
  36 #define EM3027_REG_ALARM_HOUR   0x12
  37 #define EM3027_REG_ALARM_DATE   0x13
  38 #define EM3027_REG_ALARM_DAY    0x14
  39 #define EM3027_REG_ALARM_MON    0x15
  40 #define EM3027_REG_ALARM_YEAR   0x16
  41
  42 static struct i2c_driver em3027_driver;
  43
  44 static int em3027_get_time(struct device *dev, struct rtc_time *tm)
  45 {
  46         struct i2c_client *client = to_i2c_client(dev);
  47
  48         unsigned char addr = EM3027_REG_WATCH_SEC;
  49         unsigned char buf[7];
  50
  51         struct i2c_msg msgs[] = {
  52                 {client->addr, 0, 1, &addr},            /* setup read addr */
  53                 {client->addr, I2C_M_RD, 7, buf},       /* read time/date */
  54         };
  55
  56         /* read time/date registers */
  57         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  58                 dev_err(&client->dev, "%s: read error\n", __func__);
  59                 return -EIO;
  60         }
  61
  62         tm->tm_sec      = bcd2bin(buf[0]);
  63         tm->tm_min      = bcd2bin(buf[1]);
  64         tm->tm_hour     = bcd2bin(buf[2]);
  65         tm->tm_mday     = bcd2bin(buf[3]);
  66         tm->tm_wday     = bcd2bin(buf[4]);
  67         tm->tm_mon      = bcd2bin(buf[5]);
  68         tm->tm_year     = bcd2bin(buf[6]) + 100;
  69
  70         return 0;
  71 }
  72
  73 static int em3027_set_time(struct device *dev, struct rtc_time *tm)
  74 {
  75         struct i2c_client *client = to_i2c_client(dev);
  76         unsigned char buf[8];
  77
  78         struct i2c_msg msg = {
  79                 client->addr, 0, 8, buf,        /* write time/date */
  80         };
  81
  82         buf[0] = EM3027_REG_WATCH_SEC;
  83         buf[1] = bin2bcd(tm->tm_sec);
  84         buf[2] = bin2bcd(tm->tm_min);
  85         buf[3] = bin2bcd(tm->tm_hour);
  86         buf[4] = bin2bcd(tm->tm_mday);
  87         buf[5] = bin2bcd(tm->tm_wday);
  88         buf[6] = bin2bcd(tm->tm_mon);
  89         buf[7] = bin2bcd(tm->tm_year % 100);
  90
  91         /* write time/date registers */
  92         if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
  93                 dev_err(&client->dev, "%s: write error\n", __func__);
  94                 return -EIO;
  95         }
  96
  97         return 0;
  98 }
  99
 100 static const struct rtc_class_ops em3027_rtc_ops = {
 101         .read_time = em3027_get_time,
 102         .set_time = em3027_set_time,
 103 };
 104
 105 static int em3027_probe(struct i2c_client *client,
 106                         const struct i2c_device_id *id)
 107 {
 108         struct rtc_device *rtc;
 109
 110         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 111                 return -ENODEV;
 112
 113         rtc = rtc_device_register(em3027_driver.driver.name, &client->dev,
 114                                   &em3027_rtc_ops, THIS_MODULE);
 115         if (IS_ERR(rtc))
 116                 return PTR_ERR(rtc);
 117
 118         i2c_set_clientdata(client, rtc);
 119
 120         return 0;
 121 }
 122
 123 static int em3027_remove(struct i2c_client *client)
 124 {
 125         struct rtc_device *rtc = i2c_get_clientdata(client);
 126
 127         if (rtc)
 128                 rtc_device_unregister(rtc);
 129
 130         return 0;
 131 }
 132
 133 static struct i2c_device_id em3027_id[] = {
 134         { "em3027", 0 },
 135         { }
 136 };
 137
 138 static struct i2c_driver em3027_driver = {
 139         .driver = {
 140                    .name = "rtc-em3027",
 141         },
 142         .probe = &em3027_probe,
 143         .remove = &em3027_remove,
 144         .id_table = em3027_id,
 145 };
 146
 147 module_i2c_driver(em3027_driver);
 148
 149 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
 150 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
 151 MODULE_LICENSE("GPL");