kernel/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 #include <linux/of.h>
  19
  20 /* Registers */
  21 #define EM3027_REG_ON_OFF_CTRL  0x00
  22 #define EM3027_REG_IRQ_CTRL     0x01
  23 #define EM3027_REG_IRQ_FLAGS    0x02
  24 #define EM3027_REG_STATUS       0x03
  25 #define EM3027_REG_RST_CTRL     0x04
  26
  27 #define EM3027_REG_WATCH_SEC    0x08
  28 #define EM3027_REG_WATCH_MIN    0x09
  29 #define EM3027_REG_WATCH_HOUR   0x0a
  30 #define EM3027_REG_WATCH_DATE   0x0b
  31 #define EM3027_REG_WATCH_DAY    0x0c
  32 #define EM3027_REG_WATCH_MON    0x0d
  33 #define EM3027_REG_WATCH_YEAR   0x0e
  34
  35 #define EM3027_REG_ALARM_SEC    0x10
  36 #define EM3027_REG_ALARM_MIN    0x11
  37 #define EM3027_REG_ALARM_HOUR   0x12
  38 #define EM3027_REG_ALARM_DATE   0x13
  39 #define EM3027_REG_ALARM_DAY    0x14
  40 #define EM3027_REG_ALARM_MON    0x15
  41 #define EM3027_REG_ALARM_YEAR   0x16
  42
  43 static struct i2c_driver em3027_driver;
  44
  45 static int em3027_get_time(struct device *dev, struct rtc_time *tm)
  46 {
  47         struct i2c_client *client = to_i2c_client(dev);
  48
  49         unsigned char addr = EM3027_REG_WATCH_SEC;
  50         unsigned char buf[7];
  51
  52         struct i2c_msg msgs[] = {
  53                 {/* setup read addr */
  54                         .addr = client->addr,
  55                         .len = 1,
  56                         .buf = &addr
  57                 },
  58                 {/* read time/date */
  59                         .addr = client->addr,
  60                         .flags = I2C_M_RD,
  61                         .len = 7,
  62                         .buf = buf
  63                 },
  64         };
  65
  66         /* read time/date registers */
  67         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  68                 dev_err(&client->dev, "%s: read error\n", __func__);
  69                 return -EIO;
  70         }
  71
  72         tm->tm_sec      = bcd2bin(buf[0]);
  73         tm->tm_min      = bcd2bin(buf[1]);
  74         tm->tm_hour     = bcd2bin(buf[2]);
  75         tm->tm_mday     = bcd2bin(buf[3]);
  76         tm->tm_wday     = bcd2bin(buf[4]);
  77         tm->tm_mon      = bcd2bin(buf[5]);
  78         tm->tm_year     = bcd2bin(buf[6]) + 100;
  79
  80         return 0;
  81 }
  82
  83 static int em3027_set_time(struct device *dev, struct rtc_time *tm)
  84 {
  85         struct i2c_client *client = to_i2c_client(dev);
  86         unsigned char buf[8];
  87
  88         struct i2c_msg msg = {
  89                 .addr = client->addr,
  90                 .len = 8,
  91                 .buf = buf,     /* write time/date */
  92         };
  93
  94         buf[0] = EM3027_REG_WATCH_SEC;
  95         buf[1] = bin2bcd(tm->tm_sec);
  96         buf[2] = bin2bcd(tm->tm_min);
  97         buf[3] = bin2bcd(tm->tm_hour);
  98         buf[4] = bin2bcd(tm->tm_mday);
  99         buf[5] = bin2bcd(tm->tm_wday);
 100         buf[6] = bin2bcd(tm->tm_mon);
 101         buf[7] = bin2bcd(tm->tm_year % 100);
 102
 103         /* write time/date registers */
 104         if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
 105                 dev_err(&client->dev, "%s: write error\n", __func__);
 106                 return -EIO;
 107         }
 108
 109         return 0;
 110 }
 111
 112 static const struct rtc_class_ops em3027_rtc_ops = {
 113         .read_time = em3027_get_time,
 114         .set_time = em3027_set_time,
 115 };
 116
 117 static int em3027_probe(struct i2c_client *client,
 118                         const struct i2c_device_id *id)
 119 {
 120         struct rtc_device *rtc;
 121
 122         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 123                 return -ENODEV;
 124
 125         rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name,
 126                                   &em3027_rtc_ops, THIS_MODULE);
 127         if (IS_ERR(rtc))
 128                 return PTR_ERR(rtc);
 129
 130         i2c_set_clientdata(client, rtc);
 131
 132         return 0;
 133 }
 134
 135 static struct i2c_device_id em3027_id[] = {
 136         { "em3027", 0 },
 137         { }
 138 };
 139 MODULE_DEVICE_TABLE(i2c, em3027_id);
 140
 141 #ifdef CONFIG_OF
 142 static const struct of_device_id em3027_of_match[] = {
 143         { .compatible = "emmicro,em3027", },
 144         {}
 145 };
 146 MODULE_DEVICE_TABLE(of, em3027_of_match);
 147 #endif
 148
 149 static struct i2c_driver em3027_driver = {
 150         .driver = {
 151                    .name = "rtc-em3027",
 152                    .of_match_table = of_match_ptr(em3027_of_match),
 153         },
 154         .probe = &em3027_probe,
 155         .id_table = em3027_id,
 156 };
 157
 158 module_i2c_driver(em3027_driver);
 159
 160 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
 161 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
 162 MODULE_LICENSE("GPL");