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 PCF85063_REG_CTRL1              0x00 /* status */
  20 #define PCF85063_REG_CTRL1_STOP         BIT(5)
  21 #define PCF85063_REG_CTRL2              0x01
  22
  23 #define PCF85063_REG_SC                 0x04 /* datetime */
  24 #define PCF85063_REG_SC_OS              0x80
  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 static struct i2c_driver pcf85063_driver;
  33
  34 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
  35 {
  36         s32 ret;
  37
  38         ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
  39         if (ret < 0) {
  40                 dev_err(&client->dev, "Failing to stop the clock\n");
  41                 return -EIO;
  42         }
  43
  44         /* stop the clock */
  45         ret |= PCF85063_REG_CTRL1_STOP;
  46
  47         ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
  48         if (ret < 0) {
  49                 dev_err(&client->dev, "Failing to stop the clock\n");
  50                 return -EIO;
  51         }
  52
  53         *ctrl1 = ret;
  54
  55         return 0;
  56 }
  57
  58 /*
  59  * In the routines that deal directly with the pcf85063 hardware, we use
  60  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  61  */
  62 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  63 {
  64         int rc;
  65         u8 regs[7];
  66
  67         /*
  68          * while reading, the time/date registers are blocked and not updated
  69          * anymore until the access is finished. To not lose a second
  70          * event, the access must be finished within one second. So, read all
  71          * time/date registers in one turn.
  72          */
  73         rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
  74                                            sizeof(regs), regs);
  75         if (rc != sizeof(regs)) {
  76                 dev_err(&client->dev, "date/time register read error\n");
  77                 return -EIO;
  78         }
  79
  80         /* if the clock has lost its power it makes no sense to use its time */
  81         if (regs[0] & PCF85063_REG_SC_OS) {
  82                 dev_warn(&client->dev, "Power loss detected, invalid time\n");
  83                 return -EINVAL;
  84         }
  85
  86         tm->tm_sec = bcd2bin(regs[0] & 0x7F);
  87         tm->tm_min = bcd2bin(regs[1] & 0x7F);
  88         tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
  89         tm->tm_mday = bcd2bin(regs[3] & 0x3F);
  90         tm->tm_wday = regs[4] & 0x07;
  91         tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
  92         tm->tm_year = bcd2bin(regs[6]);
  93         if (tm->tm_year < 70)
  94                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  95
  96         return rtc_valid_tm(tm);
  97 }
  98
  99 static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 100 {
 101         int rc;
 102         u8 regs[8];
 103
 104         /*
 105          * to accurately set the time, reset the divider chain and keep it in
 106          * reset state until all time/date registers are written
 107          */
 108         rc = pcf85063_stop_clock(client, &regs[7]);
 109         if (rc != 0)
 110                 return rc;
 111
 112         /* hours, minutes and seconds */
 113         regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
 114
 115         regs[1] = bin2bcd(tm->tm_min);
 116         regs[2] = bin2bcd(tm->tm_hour);
 117
 118         /* Day of month, 1 - 31 */
 119         regs[3] = bin2bcd(tm->tm_mday);
 120
 121         /* Day, 0 - 6 */
 122         regs[4] = tm->tm_wday & 0x07;
 123
 124         /* month, 1 - 12 */
 125         regs[5] = bin2bcd(tm->tm_mon + 1);
 126
 127         /* year and century */
 128         regs[6] = bin2bcd(tm->tm_year % 100);
 129
 130         /*
 131          * after all time/date registers are written, let the 'address auto
 132          * increment' feature wrap around and write register CTRL1 to re-enable
 133          * the clock divider chain again
 134          */
 135         regs[7] &= ~PCF85063_REG_CTRL1_STOP;
 136
 137         /* write all registers at once */
 138         rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
 139                                             sizeof(regs), regs);
 140         if (rc < 0) {
 141                 dev_err(&client->dev, "date/time register write error\n");
 142                 return rc;
 143         }
 144
 145         return 0;
 146 }
 147
 148 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
 149 {
 150         return pcf85063_get_datetime(to_i2c_client(dev), tm);
 151 }
 152
 153 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
 154 {
 155         return pcf85063_set_datetime(to_i2c_client(dev), tm);
 156 }
 157
 158 static const struct rtc_class_ops pcf85063_rtc_ops = {
 159         .read_time      = pcf85063_rtc_read_time,
 160         .set_time       = pcf85063_rtc_set_time
 161 };
 162
 163 static int pcf85063_probe(struct i2c_client *client,
 164                                 const struct i2c_device_id *id)
 165 {
 166         struct rtc_device *rtc;
 167
 168         dev_dbg(&client->dev, "%s\n", __func__);
 169
 170         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 171                 return -ENODEV;
 172
 173         rtc = devm_rtc_device_register(&client->dev,
 174                                        pcf85063_driver.driver.name,
 175                                        &pcf85063_rtc_ops, THIS_MODULE);
 176
 177         return PTR_ERR_OR_ZERO(rtc);
 178 }
 179
 180 static const struct i2c_device_id pcf85063_id[] = {
 181         { "pcf85063", 0 },
 182         { }
 183 };
 184 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
 185
 186 #ifdef CONFIG_OF
 187 static const struct of_device_id pcf85063_of_match[] = {
 188         { .compatible = "nxp,pcf85063" },
 189         {}
 190 };
 191 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
 192 #endif
 193
 194 static struct i2c_driver pcf85063_driver = {
 195         .driver         = {
 196                 .name   = "rtc-pcf85063",
 197                 .of_match_table = of_match_ptr(pcf85063_of_match),
 198         },
 199         .probe          = pcf85063_probe,
 200         .id_table       = pcf85063_id,
 201 };
 202
 203 module_i2c_driver(pcf85063_driver);
 204
 205 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
 206 MODULE_DESCRIPTION("PCF85063 RTC driver");
 207 MODULE_LICENSE("GPL");