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 /*
  20  * Information for this driver was pulled from the following datasheets.
  21  *
  22  *  http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
  23  *  http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
  24  *
  25  *  PCF85063A -- Rev. 6 — 18 November 2015
  26  *  PCF85063TP -- Rev. 4 — 6 May 2015
  27 */
  28
  29 #define PCF85063_REG_CTRL1              0x00 /* status */
  30 #define PCF85063_REG_CTRL1_STOP         BIT(5)
  31 #define PCF85063_REG_CTRL2              0x01
  32
  33 #define PCF85063_REG_SC                 0x04 /* datetime */
  34 #define PCF85063_REG_SC_OS              0x80
  35 #define PCF85063_REG_MN                 0x05
  36 #define PCF85063_REG_HR                 0x06
  37 #define PCF85063_REG_DM                 0x07
  38 #define PCF85063_REG_DW                 0x08
  39 #define PCF85063_REG_MO                 0x09
  40 #define PCF85063_REG_YR                 0x0A
  41
  42 static struct i2c_driver pcf85063_driver;
  43
  44 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
  45 {
  46         int rc;
  47         u8 reg;
  48
  49         rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
  50         if (rc < 0) {
  51                 dev_err(&client->dev, "Failing to stop the clock\n");
  52                 return -EIO;
  53         }
  54
  55         /* stop the clock */
  56         reg = rc | PCF85063_REG_CTRL1_STOP;
  57
  58         rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
  59         if (rc < 0) {
  60                 dev_err(&client->dev, "Failing to stop the clock\n");
  61                 return -EIO;
  62         }
  63
  64         *ctrl1 = reg;
  65
  66         return 0;
  67 }
  68
  69 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
  70 {
  71         int rc;
  72
  73         /* start the clock */
  74         ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
  75
  76         rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
  77         if (rc < 0) {
  78                 dev_err(&client->dev, "Failing to start the clock\n");
  79                 return -EIO;
  80         }
  81
  82         return 0;
  83 }
  84
  85 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
  86 {
  87         struct i2c_client *client = to_i2c_client(dev);
  88         int rc;
  89         u8 regs[7];
  90
  91         /*
  92          * while reading, the time/date registers are blocked and not updated
  93          * anymore until the access is finished. To not lose a second
  94          * event, the access must be finished within one second. So, read all
  95          * time/date registers in one turn.
  96          */
  97         rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
  98                                            sizeof(regs), regs);
  99         if (rc != sizeof(regs)) {
 100                 dev_err(&client->dev, "date/time register read error\n");
 101                 return -EIO;
 102         }
 103
 104         /* if the clock has lost its power it makes no sense to use its time */
 105         if (regs[0] & PCF85063_REG_SC_OS) {
 106                 dev_warn(&client->dev, "Power loss detected, invalid time\n");
 107                 return -EINVAL;
 108         }
 109
 110         tm->tm_sec = bcd2bin(regs[0] & 0x7F);
 111         tm->tm_min = bcd2bin(regs[1] & 0x7F);
 112         tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
 113         tm->tm_mday = bcd2bin(regs[3] & 0x3F);
 114         tm->tm_wday = regs[4] & 0x07;
 115         tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
 116         tm->tm_year = bcd2bin(regs[6]);
 117         tm->tm_year += 100;
 118
 119         return 0;
 120 }
 121
 122 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
 123 {
 124         struct i2c_client *client = to_i2c_client(dev);
 125         int rc;
 126         u8 regs[7];
 127         u8 ctrl1;
 128
 129         if ((tm->tm_year < 100) || (tm->tm_year > 199))
 130                 return -EINVAL;
 131
 132         /*
 133          * to accurately set the time, reset the divider chain and keep it in
 134          * reset state until all time/date registers are written
 135          */
 136         rc = pcf85063_stop_clock(client, &ctrl1);
 137         if (rc != 0)
 138                 return rc;
 139
 140         /* hours, minutes and seconds */
 141         regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
 142
 143         regs[1] = bin2bcd(tm->tm_min);
 144         regs[2] = bin2bcd(tm->tm_hour);
 145
 146         /* Day of month, 1 - 31 */
 147         regs[3] = bin2bcd(tm->tm_mday);
 148
 149         /* Day, 0 - 6 */
 150         regs[4] = tm->tm_wday & 0x07;
 151
 152         /* month, 1 - 12 */
 153         regs[5] = bin2bcd(tm->tm_mon + 1);
 154
 155         /* year and century */
 156         regs[6] = bin2bcd(tm->tm_year - 100);
 157
 158         /* write all registers at once */
 159         rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
 160                                             sizeof(regs), regs);
 161         if (rc < 0) {
 162                 dev_err(&client->dev, "date/time register write error\n");
 163                 return rc;
 164         }
 165
 166         /*
 167          * Write the control register as a separate action since the size of
 168          * the register space is different between the PCF85063TP and
 169          * PCF85063A devices.  The rollover point can not be used.
 170          */
 171         rc = pcf85063_start_clock(client, ctrl1);
 172         if (rc != 0)
 173                 return rc;
 174
 175         return 0;
 176 }
 177
 178 static const struct rtc_class_ops pcf85063_rtc_ops = {
 179         .read_time      = pcf85063_rtc_read_time,
 180         .set_time       = pcf85063_rtc_set_time
 181 };
 182
 183 static int pcf85063_probe(struct i2c_client *client,
 184                                 const struct i2c_device_id *id)
 185 {
 186         struct rtc_device *rtc;
 187         int err;
 188
 189         dev_dbg(&client->dev, "%s\n", __func__);
 190
 191         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 192                 return -ENODEV;
 193
 194         err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
 195         if (err < 0) {
 196                 dev_err(&client->dev, "RTC chip is not present\n");
 197                 return err;
 198         }
 199
 200         rtc = devm_rtc_device_register(&client->dev,
 201                                        pcf85063_driver.driver.name,
 202                                        &pcf85063_rtc_ops, THIS_MODULE);
 203
 204         return PTR_ERR_OR_ZERO(rtc);
 205 }
 206
 207 static const struct i2c_device_id pcf85063_id[] = {
 208         { "pcf85063", 0 },
 209         { }
 210 };
 211 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
 212
 213 #ifdef CONFIG_OF
 214 static const struct of_device_id pcf85063_of_match[] = {
 215         { .compatible = "nxp,pcf85063" },
 216         {}
 217 };
 218 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
 219 #endif
 220
 221 static struct i2c_driver pcf85063_driver = {
 222         .driver         = {
 223                 .name   = "rtc-pcf85063",
 224                 .of_match_table = of_match_ptr(pcf85063_of_match),
 225         },
 226         .probe          = pcf85063_probe,
 227         .id_table       = pcf85063_id,
 228 };
 229
 230 module_i2c_driver(pcf85063_driver);
 231
 232 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
 233 MODULE_DESCRIPTION("PCF85063 RTC driver");
 234 MODULE_LICENSE("GPL");