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         s32 ret;
  47
  48         ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
  49         if (ret < 0) {
  50                 dev_err(&client->dev, "Failing to stop the clock\n");
  51                 return -EIO;
  52         }
  53
  54         /* stop the clock */
  55         ret |= PCF85063_REG_CTRL1_STOP;
  56
  57         ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
  58         if (ret < 0) {
  59                 dev_err(&client->dev, "Failing to stop the clock\n");
  60                 return -EIO;
  61         }
  62
  63         *ctrl1 = ret;
  64
  65         return 0;
  66 }
  67
  68 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
  69 {
  70         s32 ret;
  71
  72         /* start the clock */
  73         ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
  74
  75         ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
  76         if (ret < 0) {
  77                 dev_err(&client->dev, "Failing to start the clock\n");
  78                 return -EIO;
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
  85 {
  86         struct i2c_client *client = to_i2c_client(dev);
  87         int rc;
  88         u8 regs[7];
  89
  90         /*
  91          * while reading, the time/date registers are blocked and not updated
  92          * anymore until the access is finished. To not lose a second
  93          * event, the access must be finished within one second. So, read all
  94          * time/date registers in one turn.
  95          */
  96         rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
  97                                            sizeof(regs), regs);
  98         if (rc != sizeof(regs)) {
  99                 dev_err(&client->dev, "date/time register read error\n");
 100                 return -EIO;
 101         }
 102
 103         /* if the clock has lost its power it makes no sense to use its time */
 104         if (regs[0] & PCF85063_REG_SC_OS) {
 105                 dev_warn(&client->dev, "Power loss detected, invalid time\n");
 106                 return -EINVAL;
 107         }
 108
 109         tm->tm_sec = bcd2bin(regs[0] & 0x7F);
 110         tm->tm_min = bcd2bin(regs[1] & 0x7F);
 111         tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
 112         tm->tm_mday = bcd2bin(regs[3] & 0x3F);
 113         tm->tm_wday = regs[4] & 0x07;
 114         tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
 115         tm->tm_year = bcd2bin(regs[6]);
 116         tm->tm_year += 100;
 117
 118         return 0;
 119 }
 120
 121 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
 122 {
 123         struct i2c_client *client = to_i2c_client(dev);
 124         int rc;
 125         u8 regs[7];
 126         u8 ctrl1;
 127
 128         if ((tm->tm_year < 100) || (tm->tm_year > 199))
 129                 return -EINVAL;
 130
 131         /*
 132          * to accurately set the time, reset the divider chain and keep it in
 133          * reset state until all time/date registers are written
 134          */
 135         rc = pcf85063_stop_clock(client, &ctrl1);
 136         if (rc != 0)
 137                 return rc;
 138
 139         /* hours, minutes and seconds */
 140         regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
 141
 142         regs[1] = bin2bcd(tm->tm_min);
 143         regs[2] = bin2bcd(tm->tm_hour);
 144
 145         /* Day of month, 1 - 31 */
 146         regs[3] = bin2bcd(tm->tm_mday);
 147
 148         /* Day, 0 - 6 */
 149         regs[4] = tm->tm_wday & 0x07;
 150
 151         /* month, 1 - 12 */
 152         regs[5] = bin2bcd(tm->tm_mon + 1);
 153
 154         /* year and century */
 155         regs[6] = bin2bcd(tm->tm_year - 100);
 156
 157         /* write all registers at once */
 158         rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
 159                                             sizeof(regs), regs);
 160         if (rc < 0) {
 161                 dev_err(&client->dev, "date/time register write error\n");
 162                 return rc;
 163         }
 164
 165         /*
 166          * Write the control register as a separate action since the size of
 167          * the register space is different between the PCF85063TP and
 168          * PCF85063A devices.  The rollover point can not be used.
 169          */
 170         rc = pcf85063_start_clock(client, ctrl1);
 171         if (rc != 0)
 172                 return rc;
 173
 174         return 0;
 175 }
 176
 177 static const struct rtc_class_ops pcf85063_rtc_ops = {
 178         .read_time      = pcf85063_rtc_read_time,
 179         .set_time       = pcf85063_rtc_set_time
 180 };
 181
 182 static int pcf85063_probe(struct i2c_client *client,
 183                                 const struct i2c_device_id *id)
 184 {
 185         struct rtc_device *rtc;
 186         int err;
 187
 188         dev_dbg(&client->dev, "%s\n", __func__);
 189
 190         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 191                 return -ENODEV;
 192
 193         err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
 194         if (err < 0) {
 195                 dev_err(&client->dev, "RTC chip is not present\n");
 196                 return err;
 197         }
 198
 199         rtc = devm_rtc_device_register(&client->dev,
 200                                        pcf85063_driver.driver.name,
 201                                        &pcf85063_rtc_ops, THIS_MODULE);
 202
 203         return PTR_ERR_OR_ZERO(rtc);
 204 }
 205
 206 static const struct i2c_device_id pcf85063_id[] = {
 207         { "pcf85063", 0 },
 208         { }
 209 };
 210 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
 211
 212 #ifdef CONFIG_OF
 213 static const struct of_device_id pcf85063_of_match[] = {
 214         { .compatible = "nxp,pcf85063" },
 215         {}
 216 };
 217 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
 218 #endif
 219
 220 static struct i2c_driver pcf85063_driver = {
 221         .driver         = {
 222                 .name   = "rtc-pcf85063",
 223                 .of_match_table = of_match_ptr(pcf85063_of_match),
 224         },
 225         .probe          = pcf85063_probe,
 226         .id_table       = pcf85063_id,
 227 };
 228
 229 module_i2c_driver(pcf85063_driver);
 230
 231 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
 232 MODULE_DESCRIPTION("PCF85063 RTC driver");
 233 MODULE_LICENSE("GPL");