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                 {/* setup read addr */
  53                         .addr = client->addr,
  54                         .len = 1,
  55                         .buf = &addr
  56                 },
  57                 {/* read time/date */
  58                         .addr = client->addr,
  59                         .flags = I2C_M_RD,
  60                         .len = 7,
  61                         .buf = buf
  62                 },
  63         };
  64
  65         /* read time/date registers */
  66         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  67                 dev_err(&client->dev, "%s: read error\n", __func__);
  68                 return -EIO;
  69         }
  70
  71         tm->tm_sec      = bcd2bin(buf[0]);
  72         tm->tm_min      = bcd2bin(buf[1]);
  73         tm->tm_hour     = bcd2bin(buf[2]);
  74         tm->tm_mday     = bcd2bin(buf[3]);
  75         tm->tm_wday     = bcd2bin(buf[4]);
  76         tm->tm_mon      = bcd2bin(buf[5]);
  77         tm->tm_year     = bcd2bin(buf[6]) + 100;
  78
  79         return 0;
  80 }
  81
  82 static int em3027_set_time(struct device *dev, struct rtc_time *tm)
  83 {
  84         struct i2c_client *client = to_i2c_client(dev);
  85         unsigned char buf[8];
  86
  87         struct i2c_msg msg = {
  88                 .addr = client->addr,
  89                 .len = 8,
  90                 .buf = buf,     /* write time/date */
  91         };
  92
  93         buf[0] = EM3027_REG_WATCH_SEC;
  94         buf[1] = bin2bcd(tm->tm_sec);
  95         buf[2] = bin2bcd(tm->tm_min);
  96         buf[3] = bin2bcd(tm->tm_hour);
  97         buf[4] = bin2bcd(tm->tm_mday);
  98         buf[5] = bin2bcd(tm->tm_wday);
  99         buf[6] = bin2bcd(tm->tm_mon);
 100         buf[7] = bin2bcd(tm->tm_year % 100);
 101
 102         /* write time/date registers */
 103         if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
 104                 dev_err(&client->dev, "%s: write error\n", __func__);
 105                 return -EIO;
 106         }
 107
 108         return 0;
 109 }
 110
 111 static const struct rtc_class_ops em3027_rtc_ops = {
 112         .read_time = em3027_get_time,
 113         .set_time = em3027_set_time,
 114 };
 115
 116 static int em3027_probe(struct i2c_client *client,
 117                         const struct i2c_device_id *id)
 118 {
 119         struct rtc_device *rtc;
 120
 121         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 122                 return -ENODEV;
 123
 124         rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name,
 125                                   &em3027_rtc_ops, THIS_MODULE);
 126         if (IS_ERR(rtc))
 127                 return PTR_ERR(rtc);
 128
 129         i2c_set_clientdata(client, rtc);
 130
 131         return 0;
 132 }
 133
 134 static struct i2c_device_id em3027_id[] = {
 135         { "em3027", 0 },
 136         { }
 137 };
 138
 139 static struct i2c_driver em3027_driver = {
 140         .driver = {
 141                    .name = "rtc-em3027",
 142         },
 143         .probe = &em3027_probe,
 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");