drivers/rtc/rtc-em3027.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * An rtc/i2c driver for the EM Microelectronic EM3027
   4  * Copyright 2011 CompuLab, Ltd.
   5  *
   6  * Author: Mike Rapoport <mike@compulab.co.il>
   7  *
   8  * Based on rtc-ds1672.c by Alessandro Zummo <a.zummo@towertech.it>
   9  */
  10
  11 #include <linux/i2c.h>
  12 #include <linux/rtc.h>
  13 #include <linux/bcd.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16
  17 /* Registers */
  18 #define EM3027_REG_ON_OFF_CTRL  0x00
  19 #define EM3027_REG_IRQ_CTRL     0x01
  20 #define EM3027_REG_IRQ_FLAGS    0x02
  21 #define EM3027_REG_STATUS       0x03
  22 #define EM3027_REG_RST_CTRL     0x04
  23
  24 #define EM3027_REG_WATCH_SEC    0x08
  25 #define EM3027_REG_WATCH_MIN    0x09
  26 #define EM3027_REG_WATCH_HOUR   0x0a
  27 #define EM3027_REG_WATCH_DATE   0x0b
  28 #define EM3027_REG_WATCH_DAY    0x0c
  29 #define EM3027_REG_WATCH_MON    0x0d
  30 #define EM3027_REG_WATCH_YEAR   0x0e
  31
  32 #define EM3027_REG_ALARM_SEC    0x10
  33 #define EM3027_REG_ALARM_MIN    0x11
  34 #define EM3027_REG_ALARM_HOUR   0x12
  35 #define EM3027_REG_ALARM_DATE   0x13
  36 #define EM3027_REG_ALARM_DAY    0x14
  37 #define EM3027_REG_ALARM_MON    0x15
  38 #define EM3027_REG_ALARM_YEAR   0x16
  39
  40 static struct i2c_driver em3027_driver;
  41
  42 static int em3027_get_time(struct device *dev, struct rtc_time *tm)
  43 {
  44         struct i2c_client *client = to_i2c_client(dev);
  45
  46         unsigned char addr = EM3027_REG_WATCH_SEC;
  47         unsigned char buf[7];
  48
  49         struct i2c_msg msgs[] = {
  50                 {/* setup read addr */
  51                         .addr = client->addr,
  52                         .len = 1,
  53                         .buf = &addr
  54                 },
  55                 {/* read time/date */
  56                         .addr = client->addr,
  57                         .flags = I2C_M_RD,
  58                         .len = 7,
  59                         .buf = buf
  60                 },
  61         };
  62
  63         /* read time/date registers */
  64         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  65                 dev_err(&client->dev, "%s: read error\n", __func__);
  66                 return -EIO;
  67         }
  68
  69         tm->tm_sec      = bcd2bin(buf[0]);
  70         tm->tm_min      = bcd2bin(buf[1]);
  71         tm->tm_hour     = bcd2bin(buf[2]);
  72         tm->tm_mday     = bcd2bin(buf[3]);
  73         tm->tm_wday     = bcd2bin(buf[4]);
  74         tm->tm_mon      = bcd2bin(buf[5]) - 1;
  75         tm->tm_year     = bcd2bin(buf[6]) + 100;
  76
  77         return 0;
  78 }
  79
  80 static int em3027_set_time(struct device *dev, struct rtc_time *tm)
  81 {
  82         struct i2c_client *client = to_i2c_client(dev);
  83         unsigned char buf[8];
  84
  85         struct i2c_msg msg = {
  86                 .addr = client->addr,
  87                 .len = 8,
  88                 .buf = buf,     /* write time/date */
  89         };
  90
  91         buf[0] = EM3027_REG_WATCH_SEC;
  92         buf[1] = bin2bcd(tm->tm_sec);
  93         buf[2] = bin2bcd(tm->tm_min);
  94         buf[3] = bin2bcd(tm->tm_hour);
  95         buf[4] = bin2bcd(tm->tm_mday);
  96         buf[5] = bin2bcd(tm->tm_wday);
  97         buf[6] = bin2bcd(tm->tm_mon + 1);
  98         buf[7] = bin2bcd(tm->tm_year % 100);
  99
 100         /* write time/date registers */
 101         if ((i2c_transfer(client->adapter, &msg, 1)) != 1) {
 102                 dev_err(&client->dev, "%s: write error\n", __func__);
 103                 return -EIO;
 104         }
 105
 106         return 0;
 107 }
 108
 109 static const struct rtc_class_ops em3027_rtc_ops = {
 110         .read_time = em3027_get_time,
 111         .set_time = em3027_set_time,
 112 };
 113
 114 static int em3027_probe(struct i2c_client *client)
 115 {
 116         struct rtc_device *rtc;
 117
 118         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 119                 return -ENODEV;
 120
 121         rtc = devm_rtc_device_register(&client->dev, em3027_driver.driver.name,
 122                                   &em3027_rtc_ops, THIS_MODULE);
 123         if (IS_ERR(rtc))
 124                 return PTR_ERR(rtc);
 125
 126         i2c_set_clientdata(client, rtc);
 127
 128         return 0;
 129 }
 130
 131 static const struct i2c_device_id em3027_id[] = {
 132         { "em3027", 0 },
 133         { }
 134 };
 135 MODULE_DEVICE_TABLE(i2c, em3027_id);
 136
 137 #ifdef CONFIG_OF
 138 static const struct of_device_id em3027_of_match[] = {
 139         { .compatible = "emmicro,em3027", },
 140         {}
 141 };
 142 MODULE_DEVICE_TABLE(of, em3027_of_match);
 143 #endif
 144
 145 static struct i2c_driver em3027_driver = {
 146         .driver = {
 147                    .name = "rtc-em3027",
 148                    .of_match_table = of_match_ptr(em3027_of_match),
 149         },
 150         .probe = em3027_probe,
 151         .id_table = em3027_id,
 152 };
 153
 154 module_i2c_driver(em3027_driver);
 155
 156 MODULE_AUTHOR("Mike Rapoport <mike@compulab.co.il>");
 157 MODULE_DESCRIPTION("EM Microelectronic EM3027 RTC driver");
 158 MODULE_LICENSE("GPL");