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
  18 /* Registers */
  19 #define EM3027_REG_ON_OFF_CTRL  0x00
  20 #define EM3027_REG_IRQ_CTRL     0x01
  21 #define EM3027_REG_IRQ_FLAGS    0x02
  22 #define EM3027_REG_STATUS       0x03
  23 #define EM3027_REG_RST_CTRL     0x04
  24
  25 #define EM3027_REG_WATCH_SEC    0x08
  26 #define EM3027_REG_WATCH_MIN    0x09
  27 #define EM3027_REG_WATCH_HOUR   0x0a
  28 #define EM3027_REG_WATCH_DATE   0x0b
  29 #define EM3027_REG_WATCH_DAY    0x0c
  30 #define EM3027_REG_WATCH_MON    0x0d
  31 #define EM3027_REG_WATCH_YEAR   0x0e
  32
  33 #define EM3027_REG_ALARM_SEC    0x10
  34 #define EM3027_REG_ALARM_MIN    0x11
  35 #define EM3027_REG_ALARM_HOUR   0x12
  36 #define EM3027_REG_ALARM_DATE   0x13
  37 #define EM3027_REG_ALARM_DAY    0x14
  38 #define EM3027_REG_ALARM_MON    0x15
  39 #define EM3027_REG_ALARM_YEAR   0x16
  40
  41 static struct i2c_driver em3027_driver;
  42
  43 static int em3027_get_time(struct device *dev, struct rtc_time *tm)
  44 {
  45         struct i2c_client *client = to_i2c_client(dev);
  46
  47         unsigned char addr = EM3027_REG_WATCH_SEC;
  48         unsigned char buf[7];
  49
  50         struct i2c_msg msgs[] = {
  51                 {client->addr, 0, 1, &addr},            /* setup read addr */
  52                 {client->addr, I2C_M_RD, 7, buf},       /* read time/date */
  53         };
  54
  55         /* read time/date registers */
  56         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  57                 dev_err(&client->dev, "%s: read error\n", __func__);
  58                 return -EIO;
  59         }
  60
  61         tm->tm_sec      = bcd2bin(buf[0]);
  62         tm->tm_min      = bcd2bin(buf[1]);
  63         tm->tm_hour     = bcd2bin(buf[2]);
  64         tm->tm_mday     = bcd2bin(buf[3]);
  65         tm->tm_wday     = bcd2bin(buf[4]);
  66         tm->tm_mon      = bcd2bin(buf[5]);
  67         tm->tm_year     = bcd2bin(buf[6]) + 100;
  68
  69         return 0;
  70 }
  71
  72 static int em3027_set_time(struct device *dev, struct rtc_time *tm)
  73 {
  74         struct i2c_client *client = to_i2c_client(dev);
  75         unsigned char buf[8];
  76
  77         struct i2c_msg msg = {
  78                 client->addr, 0, 8, buf,        /* write time/date */
  79         };
  80
  81         buf[0] = EM3027_REG_WATCH_SEC;
  82         buf[1] = bin2bcd(tm->tm_sec);
  83         buf[2] = bin2bcd(tm->tm_min);
  84         buf[3] = bin2bcd(tm->tm_hour);
  85         buf[4] = bin2bcd(tm->tm_mday);
  86         buf[5] = bin2bcd(tm->tm_wday);
  87         buf[6] = bin2bcd(tm->tm_mon);
  88         buf[7] = bin2bcd(tm->tm_year % 100);
  89
  90         /* write time/date registers */
  91         if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
  92                 dev_err(&client->dev, "%s: write error\n", __func__);
  93                 return -EIO;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static const struct rtc_class_ops em3027_rtc_ops = {
 100         .read_time = em3027_get_time,
 101         .set_time = em3027_set_time,
 102 };
 103
 104 static int em3027_probe(struct i2c_client *client,
 105                         const struct i2c_device_id *id)
 106 {
 107         struct rtc_device *rtc;
 108
 109         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 110                 return -ENODEV;
 111
 112         rtc = rtc_device_register(em3027_driver.driver.name, &client->dev,
 113                                   &em3027_rtc_ops, THIS_MODULE);
 114         if (IS_ERR(rtc))
 115                 return PTR_ERR(rtc);
 116
 117         i2c_set_clientdata(client, rtc);
 118
 119         return 0;
 120 }
 121
 122 static int em3027_remove(struct i2c_client *client)
 123 {
 124         struct rtc_device *rtc = i2c_get_clientdata(client);
 125
 126         if (rtc)
 127                 rtc_device_unregister(rtc);
 128
 129         return 0;
 130 }
 131
 132 static struct i2c_device_id em3027_id[] = {
 133         { "em3027", 0 },
 134         { }
 135 };
 136
 137 static struct i2c_driver em3027_driver = {
 138         .driver = {
 139                    .name = "rtc-em3027",
 140         },
 141         .probe = &em3027_probe,
 142         .remove = &em3027_remove,
 143         .id_table = em3027_id,
 144 };
 145
 146 static int __init em3027_init(void)
 147 {
 148         return i2c_add_driver(&em3027_driver);
 149 }
 150
 151 static void __exit em3027_exit(void)
 152 {
 153         i2c_del_driver(&em3027_driver);
 154 }
 155
 156 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
 157 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
 158 MODULE_LICENSE("GPL");
 159
 160 module_init(em3027_init);
 161 module_exit(em3027_exit);