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_SC_OS              0x80
  26 #define PCF85063_REG_MN                 0x05
  27 #define PCF85063_REG_HR                 0x06
  28 #define PCF85063_REG_DM                 0x07
  29 #define PCF85063_REG_DW                 0x08
  30 #define PCF85063_REG_MO                 0x09
  31 #define PCF85063_REG_YR                 0x0A
  32
  33 #define PCF85063_MO_C                   0x80 /* century */
  34
  35 static struct i2c_driver pcf85063_driver;
  36
  37 struct pcf85063 {
  38         struct rtc_device *rtc;
  39         int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
  40         int voltage_low; /* indicates if a low_voltage was detected */
  41 };
  42
  43 /*
  44  * In the routines that deal directly with the pcf85063 hardware, we use
  45  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  46  */
  47 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  48 {
  49         int rc;
  50         struct pcf85063 *pcf85063 = i2c_get_clientdata(client);
  51         u8 regs[7];
  52
  53         /*
  54          * while reading, the time/date registers are blocked and not updated
  55          * anymore until the access is finished. To not lose a second
  56          * event, the access must be finished within one second. So, read all
  57          * time/date registers in one turn.
  58          */
  59         rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
  60                                            sizeof(regs), regs);
  61         if (rc != sizeof(regs)) {
  62                 dev_err(&client->dev, "date/time register read error\n");
  63                 return -EIO;
  64         }
  65
  66         /* if the clock has lost its power it makes no sense to use its time */
  67         if (regs[0] & PCF85063_REG_SC_OS) {
  68                 dev_warn(&client->dev, "Power loss detected, invalid time\n");
  69                 return -EINVAL;
  70         }
  71
  72         tm->tm_sec = bcd2bin(regs[0] & 0x7F);
  73         tm->tm_min = bcd2bin(regs[1] & 0x7F);
  74         tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
  75         tm->tm_mday = bcd2bin(regs[3] & 0x3F);
  76         tm->tm_wday = regs[4] & 0x07;
  77         tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
  78         tm->tm_year = bcd2bin(regs[6]);
  79         if (tm->tm_year < 70)
  80                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  81         /* detect the polarity heuristically. see note above. */
  82         pcf85063->c_polarity = (regs[5] & PCF85063_MO_C) ?
  83                 (tm->tm_year >= 100) : (tm->tm_year < 100);
  84
  85         return rtc_valid_tm(tm);
  86 }
  87
  88 static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
  89 {
  90         int i = 0, err = 0;
  91         unsigned char buf[11];
  92
  93         /* Control & status */
  94         buf[PCF85063_REG_CTRL1] = 0;
  95         buf[PCF85063_REG_CTRL2] = 5;
  96
  97         /* hours, minutes and seconds */
  98         buf[PCF85063_REG_SC] = bin2bcd(tm->tm_sec) & 0x7F;
  99
 100         buf[PCF85063_REG_MN] = bin2bcd(tm->tm_min);
 101         buf[PCF85063_REG_HR] = bin2bcd(tm->tm_hour);
 102
 103         /* Day of month, 1 - 31 */
 104         buf[PCF85063_REG_DM] = bin2bcd(tm->tm_mday);
 105
 106         /* Day, 0 - 6 */
 107         buf[PCF85063_REG_DW] = tm->tm_wday & 0x07;
 108
 109         /* month, 1 - 12 */
 110         buf[PCF85063_REG_MO] = bin2bcd(tm->tm_mon + 1);
 111
 112         /* year and century */
 113         buf[PCF85063_REG_YR] = bin2bcd(tm->tm_year % 100);
 114
 115         /* write register's data */
 116         for (i = 0; i < sizeof(buf); i++) {
 117                 unsigned char data[2] = { i, buf[i] };
 118
 119                 err = i2c_master_send(client, data, sizeof(data));
 120                 if (err != sizeof(data)) {
 121                         dev_err(&client->dev, "%s: err=%d addr=%02x, data=%02x\n",
 122                                         __func__, err, data[0], data[1]);
 123                         return -EIO;
 124                 }
 125         }
 126
 127         return 0;
 128 }
 129
 130 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
 131 {
 132         return pcf85063_get_datetime(to_i2c_client(dev), tm);
 133 }
 134
 135 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
 136 {
 137         return pcf85063_set_datetime(to_i2c_client(dev), tm);
 138 }
 139
 140 static const struct rtc_class_ops pcf85063_rtc_ops = {
 141         .read_time      = pcf85063_rtc_read_time,
 142         .set_time       = pcf85063_rtc_set_time
 143 };
 144
 145 static int pcf85063_probe(struct i2c_client *client,
 146                                 const struct i2c_device_id *id)
 147 {
 148         struct pcf85063 *pcf85063;
 149
 150         dev_dbg(&client->dev, "%s\n", __func__);
 151
 152         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 153                 return -ENODEV;
 154
 155         pcf85063 = devm_kzalloc(&client->dev, sizeof(struct pcf85063),
 156                                 GFP_KERNEL);
 157         if (!pcf85063)
 158                 return -ENOMEM;
 159
 160         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 161
 162         i2c_set_clientdata(client, pcf85063);
 163
 164         pcf85063->rtc = devm_rtc_device_register(&client->dev,
 165                                 pcf85063_driver.driver.name,
 166                                 &pcf85063_rtc_ops, THIS_MODULE);
 167
 168         return PTR_ERR_OR_ZERO(pcf85063->rtc);
 169 }
 170
 171 static const struct i2c_device_id pcf85063_id[] = {
 172         { "pcf85063", 0 },
 173         { }
 174 };
 175 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
 176
 177 #ifdef CONFIG_OF
 178 static const struct of_device_id pcf85063_of_match[] = {
 179         { .compatible = "nxp,pcf85063" },
 180         {}
 181 };
 182 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
 183 #endif
 184
 185 static struct i2c_driver pcf85063_driver = {
 186         .driver         = {
 187                 .name   = "rtc-pcf85063",
 188                 .of_match_table = of_match_ptr(pcf85063_of_match),
 189         },
 190         .probe          = pcf85063_probe,
 191         .id_table       = pcf85063_id,
 192 };
 193
 194 module_i2c_driver(pcf85063_driver);
 195
 196 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
 197 MODULE_DESCRIPTION("PCF85063 RTC driver");
 198 MODULE_LICENSE("GPL");
 199 MODULE_VERSION(DRV_VERSION);