drivers/rtc/rtc-pcf85063.c

   1 /*
   2  * An I2C driver for the PCF85063 RTC
   3  * Copyright 2014 Rose Technology
   4  *
   5  * Author: Søren Andersen <san@rosetechnology.dk>
   6  * Maintainers: http://www.nslu2-linux.org/
   7  *
   8  * based on the other drivers in this same directory.
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14 #include <linux/i2c.h>
  15 #include <linux/bcd.h>
  16 #include <linux/rtc.h>
  17 #include <linux/module.h>
  18
  19 #define DRV_VERSION "0.0.1"
  20
  21 #define PCF85063_REG_CTRL1              0x00 /* status */
  22 #define PCF85063_REG_CTRL2              0x01
  23
  24 #define PCF85063_REG_SC                 0x04 /* datetime */
  25 #define PCF85063_REG_MN                 0x05
  26 #define PCF85063_REG_HR                 0x06
  27 #define PCF85063_REG_DM                 0x07
  28 #define PCF85063_REG_DW                 0x08
  29 #define PCF85063_REG_MO                 0x09
  30 #define PCF85063_REG_YR                 0x0A
  31
  32 #define PCF85063_MO_C                   0x80 /* century */
  33
  34 static struct i2c_driver pcf85063_driver;
  35
  36 struct pcf85063 {
  37         struct rtc_device *rtc;
  38         int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
  39         int voltage_low; /* indicates if a low_voltage was detected */
  40 };
  41
  42 /*
  43  * In the routines that deal directly with the pcf85063 hardware, we use
  44  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  45  */
  46 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  47 {
  48         struct pcf85063 *pcf85063 = i2c_get_clientdata(client);
  49         unsigned char buf[13] = { PCF85063_REG_CTRL1 };
  50         struct i2c_msg msgs[] = {
  51                 {/* setup read ptr */
  52                         .addr = client->addr,
  53                         .len = 1,
  54                         .buf = buf
  55                 },
  56                 {/* read status + date */
  57                         .addr = client->addr,
  58                         .flags = I2C_M_RD,
  59                         .len = 13,
  60                         .buf = buf
  61                 },
  62         };
  63
  64         /* read registers */
  65         if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
  66                 dev_err(&client->dev, "%s: read error\n", __func__);
  67                 return -EIO;
  68         }
  69
  70         tm->tm_sec = bcd2bin(buf[PCF85063_REG_SC] & 0x7F);
  71         tm->tm_min = bcd2bin(buf[PCF85063_REG_MN] & 0x7F);
  72         tm->tm_hour = bcd2bin(buf[PCF85063_REG_HR] & 0x3F); /* rtc hr 0-23 */
  73         tm->tm_mday = bcd2bin(buf[PCF85063_REG_DM] & 0x3F);
  74         tm->tm_wday = buf[PCF85063_REG_DW] & 0x07;
  75         tm->tm_mon = bcd2bin(buf[PCF85063_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
  76         tm->tm_year = bcd2bin(buf[PCF85063_REG_YR]);
  77         if (tm->tm_year < 70)
  78                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  79         /* detect the polarity heuristically. see note above. */
  80         pcf85063->c_polarity = (buf[PCF85063_REG_MO] & PCF85063_MO_C) ?
  81                 (tm->tm_year >= 100) : (tm->tm_year < 100);
  82
  83         /* the clock can give out invalid datetime, but we cannot return
  84          * -EINVAL otherwise hwclock will refuse to set the time on bootup.
  85          */
  86         if (rtc_valid_tm(tm) < 0)
  87                 dev_err(&client->dev, "retrieved date/time is not valid.\n");
  88
  89         return 0;
  90 }
  91
  92 static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
  93 {
  94         int i = 0, err = 0;
  95         unsigned char buf[11];
  96
  97         /* Control & status */
  98         buf[PCF85063_REG_CTRL1] = 0;
  99         buf[PCF85063_REG_CTRL2] = 5;
 100
 101         /* hours, minutes and seconds */
 102         buf[PCF85063_REG_SC] = bin2bcd(tm->tm_sec) & 0x7F;
 103
 104         buf[PCF85063_REG_MN] = bin2bcd(tm->tm_min);
 105         buf[PCF85063_REG_HR] = bin2bcd(tm->tm_hour);
 106
 107         /* Day of month, 1 - 31 */
 108         buf[PCF85063_REG_DM] = bin2bcd(tm->tm_mday);
 109
 110         /* Day, 0 - 6 */
 111         buf[PCF85063_REG_DW] = tm->tm_wday & 0x07;
 112
 113         /* month, 1 - 12 */
 114         buf[PCF85063_REG_MO] = bin2bcd(tm->tm_mon + 1);
 115
 116         /* year and century */
 117         buf[PCF85063_REG_YR] = bin2bcd(tm->tm_year % 100);
 118
 119         /* write register's data */
 120         for (i = 0; i < sizeof(buf); i++) {
 121                 unsigned char data[2] = { i, buf[i] };
 122
 123                 err = i2c_master_send(client, data, sizeof(data));
 124                 if (err != sizeof(data)) {
 125                         dev_err(&client->dev, "%s: err=%d addr=%02x, data=%02x\n",
 126                                         __func__, err, data[0], data[1]);
 127                         return -EIO;
 128                 }
 129         }
 130
 131         return 0;
 132 }
 133
 134 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
 135 {
 136         return pcf85063_get_datetime(to_i2c_client(dev), tm);
 137 }
 138
 139 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
 140 {
 141         return pcf85063_set_datetime(to_i2c_client(dev), tm);
 142 }
 143
 144 static const struct rtc_class_ops pcf85063_rtc_ops = {
 145         .read_time      = pcf85063_rtc_read_time,
 146         .set_time       = pcf85063_rtc_set_time
 147 };
 148
 149 static int pcf85063_probe(struct i2c_client *client,
 150                                 const struct i2c_device_id *id)
 151 {
 152         struct pcf85063 *pcf85063;
 153
 154         dev_dbg(&client->dev, "%s\n", __func__);
 155
 156         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 157                 return -ENODEV;
 158
 159         pcf85063 = devm_kzalloc(&client->dev, sizeof(struct pcf85063),
 160                                 GFP_KERNEL);
 161         if (!pcf85063)
 162                 return -ENOMEM;
 163
 164         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 165
 166         i2c_set_clientdata(client, pcf85063);
 167
 168         pcf85063->rtc = devm_rtc_device_register(&client->dev,
 169                                 pcf85063_driver.driver.name,
 170                                 &pcf85063_rtc_ops, THIS_MODULE);
 171
 172         return PTR_ERR_OR_ZERO(pcf85063->rtc);
 173 }
 174
 175 static const struct i2c_device_id pcf85063_id[] = {
 176         { "pcf85063", 0 },
 177         { }
 178 };
 179 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
 180
 181 #ifdef CONFIG_OF
 182 static const struct of_device_id pcf85063_of_match[] = {
 183         { .compatible = "nxp,pcf85063" },
 184         {}
 185 };
 186 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
 187 #endif
 188
 189 static struct i2c_driver pcf85063_driver = {
 190         .driver         = {
 191                 .name   = "rtc-pcf85063",
 192                 .owner  = THIS_MODULE,
 193                 .of_match_table = of_match_ptr(pcf85063_of_match),
 194         },
 195         .probe          = pcf85063_probe,
 196         .id_table       = pcf85063_id,
 197 };
 198
 199 module_i2c_driver(pcf85063_driver);
 200
 201 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
 202 MODULE_DESCRIPTION("PCF85063 RTC driver");
 203 MODULE_LICENSE("GPL");
 204 MODULE_VERSION(DRV_VERSION);