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_CTRL1_STOP         BIT(5)
  23 #define PCF85063_REG_CTRL2              0x01
  24
  25 #define PCF85063_REG_SC                 0x04 /* datetime */
  26 #define PCF85063_REG_SC_OS              0x80
  27 #define PCF85063_REG_MN                 0x05
  28 #define PCF85063_REG_HR                 0x06
  29 #define PCF85063_REG_DM                 0x07
  30 #define PCF85063_REG_DW                 0x08
  31 #define PCF85063_REG_MO                 0x09
  32 #define PCF85063_REG_YR                 0x0A
  33
  34 #define PCF85063_MO_C                   0x80 /* century */
  35
  36 static struct i2c_driver pcf85063_driver;
  37
  38 struct pcf85063 {
  39         struct rtc_device *rtc;
  40         int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
  41         int voltage_low; /* indicates if a low_voltage was detected */
  42 };
  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 /*
  69  * In the routines that deal directly with the pcf85063 hardware, we use
  70  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  71  */
  72 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  73 {
  74         int rc;
  75         struct pcf85063 *pcf85063 = i2c_get_clientdata(client);
  76         u8 regs[7];
  77
  78         /*
  79          * while reading, the time/date registers are blocked and not updated
  80          * anymore until the access is finished. To not lose a second
  81          * event, the access must be finished within one second. So, read all
  82          * time/date registers in one turn.
  83          */
  84         rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
  85                                            sizeof(regs), regs);
  86         if (rc != sizeof(regs)) {
  87                 dev_err(&client->dev, "date/time register read error\n");
  88                 return -EIO;
  89         }
  90
  91         /* if the clock has lost its power it makes no sense to use its time */
  92         if (regs[0] & PCF85063_REG_SC_OS) {
  93                 dev_warn(&client->dev, "Power loss detected, invalid time\n");
  94                 return -EINVAL;
  95         }
  96
  97         tm->tm_sec = bcd2bin(regs[0] & 0x7F);
  98         tm->tm_min = bcd2bin(regs[1] & 0x7F);
  99         tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
 100         tm->tm_mday = bcd2bin(regs[3] & 0x3F);
 101         tm->tm_wday = regs[4] & 0x07;
 102         tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
 103         tm->tm_year = bcd2bin(regs[6]);
 104         if (tm->tm_year < 70)
 105                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 106         /* detect the polarity heuristically. see note above. */
 107         pcf85063->c_polarity = (regs[5] & PCF85063_MO_C) ?
 108                 (tm->tm_year >= 100) : (tm->tm_year < 100);
 109
 110         return rtc_valid_tm(tm);
 111 }
 112
 113 static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 114 {
 115         int rc;
 116         u8 regs[8];
 117
 118         /*
 119          * to accurately set the time, reset the divider chain and keep it in
 120          * reset state until all time/date registers are written
 121          */
 122         rc = pcf85063_stop_clock(client, &regs[7]);
 123         if (rc != 0)
 124                 return rc;
 125
 126         /* hours, minutes and seconds */
 127         regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
 128
 129         regs[1] = bin2bcd(tm->tm_min);
 130         regs[2] = bin2bcd(tm->tm_hour);
 131
 132         /* Day of month, 1 - 31 */
 133         regs[3] = bin2bcd(tm->tm_mday);
 134
 135         /* Day, 0 - 6 */
 136         regs[4] = tm->tm_wday & 0x07;
 137
 138         /* month, 1 - 12 */
 139         regs[5] = bin2bcd(tm->tm_mon + 1);
 140
 141         /* year and century */
 142         regs[6] = bin2bcd(tm->tm_year % 100);
 143
 144         /*
 145          * after all time/date registers are written, let the 'address auto
 146          * increment' feature wrap around and write register CTRL1 to re-enable
 147          * the clock divider chain again
 148          */
 149         regs[7] &= ~PCF85063_REG_CTRL1_STOP;
 150
 151         /* write all registers at once */
 152         rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
 153                                             sizeof(regs), regs);
 154         if (rc < 0) {
 155                 dev_err(&client->dev, "date/time register write error\n");
 156                 return rc;
 157         }
 158
 159         return 0;
 160 }
 161
 162 static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
 163 {
 164         return pcf85063_get_datetime(to_i2c_client(dev), tm);
 165 }
 166
 167 static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
 168 {
 169         return pcf85063_set_datetime(to_i2c_client(dev), tm);
 170 }
 171
 172 static const struct rtc_class_ops pcf85063_rtc_ops = {
 173         .read_time      = pcf85063_rtc_read_time,
 174         .set_time       = pcf85063_rtc_set_time
 175 };
 176
 177 static int pcf85063_probe(struct i2c_client *client,
 178                                 const struct i2c_device_id *id)
 179 {
 180         struct pcf85063 *pcf85063;
 181
 182         dev_dbg(&client->dev, "%s\n", __func__);
 183
 184         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 185                 return -ENODEV;
 186
 187         pcf85063 = devm_kzalloc(&client->dev, sizeof(struct pcf85063),
 188                                 GFP_KERNEL);
 189         if (!pcf85063)
 190                 return -ENOMEM;
 191
 192         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 193
 194         i2c_set_clientdata(client, pcf85063);
 195
 196         pcf85063->rtc = devm_rtc_device_register(&client->dev,
 197                                 pcf85063_driver.driver.name,
 198                                 &pcf85063_rtc_ops, THIS_MODULE);
 199
 200         return PTR_ERR_OR_ZERO(pcf85063->rtc);
 201 }
 202
 203 static const struct i2c_device_id pcf85063_id[] = {
 204         { "pcf85063", 0 },
 205         { }
 206 };
 207 MODULE_DEVICE_TABLE(i2c, pcf85063_id);
 208
 209 #ifdef CONFIG_OF
 210 static const struct of_device_id pcf85063_of_match[] = {
 211         { .compatible = "nxp,pcf85063" },
 212         {}
 213 };
 214 MODULE_DEVICE_TABLE(of, pcf85063_of_match);
 215 #endif
 216
 217 static struct i2c_driver pcf85063_driver = {
 218         .driver         = {
 219                 .name   = "rtc-pcf85063",
 220                 .of_match_table = of_match_ptr(pcf85063_of_match),
 221         },
 222         .probe          = pcf85063_probe,
 223         .id_table       = pcf85063_id,
 224 };
 225
 226 module_i2c_driver(pcf85063_driver);
 227
 228 MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
 229 MODULE_DESCRIPTION("PCF85063 RTC driver");
 230 MODULE_LICENSE("GPL");
 231 MODULE_VERSION(DRV_VERSION);