drivers/rtc/rtc-pcf2127.c

   1 /*
   2  * An I2C driver for the NXP PCF2127 RTC
   3  * Copyright 2013 Til-Technologies
   4  *
   5  * Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
   6  *
   7  * based on the other drivers in this same directory.
   8  *
   9  * http://www.nxp.com/documents/data_sheet/PCF2127AT.pdf
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/i2c.h>
  17 #include <linux/bcd.h>
  18 #include <linux/rtc.h>
  19 #include <linux/slab.h>
  20 #include <linux/module.h>
  21 #include <linux/of.h>
  22
  23 #define PCF2127_REG_CTRL1       (0x00)  /* Control Register 1 */
  24 #define PCF2127_REG_CTRL2       (0x01)  /* Control Register 2 */
  25
  26 #define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
  27 #define PCF2127_REG_CTRL3_BLF           BIT(2)
  28
  29 #define PCF2127_REG_SC          (0x03)  /* datetime */
  30 #define PCF2127_REG_MN          (0x04)
  31 #define PCF2127_REG_HR          (0x05)
  32 #define PCF2127_REG_DM          (0x06)
  33 #define PCF2127_REG_DW          (0x07)
  34 #define PCF2127_REG_MO          (0x08)
  35 #define PCF2127_REG_YR          (0x09)
  36
  37 #define PCF2127_OSF             BIT(7)  /* Oscillator Fail flag */
  38
  39 static struct i2c_driver pcf2127_driver;
  40
  41 struct pcf2127 {
  42         struct rtc_device *rtc;
  43 };
  44
  45 /*
  46  * In the routines that deal directly with the pcf2127 hardware, we use
  47  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  48  */
  49 static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  50 {
  51         unsigned char buf[10] = { PCF2127_REG_CTRL1 };
  52
  53         /* read registers */
  54         if (i2c_master_send(client, buf, 1) != 1 ||
  55                 i2c_master_recv(client, buf, sizeof(buf)) != sizeof(buf)) {
  56                 dev_err(&client->dev, "%s: read error\n", __func__);
  57                 return -EIO;
  58         }
  59
  60         if (buf[PCF2127_REG_CTRL3] & PCF2127_REG_CTRL3_BLF)
  61                 dev_info(&client->dev,
  62                         "low voltage detected, check/replace RTC battery.\n");
  63
  64         if (buf[PCF2127_REG_SC] & PCF2127_OSF) {
  65                 /*
  66                  * no need clear the flag here,
  67                  * it will be cleared once the new date is saved
  68                  */
  69                 dev_warn(&client->dev,
  70                          "oscillator stop detected, date/time is not reliable\n");
  71                 return -EINVAL;
  72         }
  73
  74         dev_dbg(&client->dev,
  75                 "%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
  76                 "sec=%02x, min=%02x, hr=%02x, "
  77                 "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
  78                 __func__,
  79                 buf[0], buf[1], buf[2],
  80                 buf[3], buf[4], buf[5],
  81                 buf[6], buf[7], buf[8], buf[9]);
  82
  83
  84         tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
  85         tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
  86         tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
  87         tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
  88         tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
  89         tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
  90         tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
  91         if (tm->tm_year < 70)
  92                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  93
  94         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  95                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  96                 __func__,
  97                 tm->tm_sec, tm->tm_min, tm->tm_hour,
  98                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  99
 100         return rtc_valid_tm(tm);
 101 }
 102
 103 static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 104 {
 105         unsigned char buf[8];
 106         int i = 0, err;
 107
 108         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 109                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 110                 __func__,
 111                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 112                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 113
 114         /* start register address */
 115         buf[i++] = PCF2127_REG_SC;
 116
 117         /* hours, minutes and seconds */
 118         buf[i++] = bin2bcd(tm->tm_sec); /* this will also clear OSF flag */
 119         buf[i++] = bin2bcd(tm->tm_min);
 120         buf[i++] = bin2bcd(tm->tm_hour);
 121         buf[i++] = bin2bcd(tm->tm_mday);
 122         buf[i++] = tm->tm_wday & 0x07;
 123
 124         /* month, 1 - 12 */
 125         buf[i++] = bin2bcd(tm->tm_mon + 1);
 126
 127         /* year */
 128         buf[i++] = bin2bcd(tm->tm_year % 100);
 129
 130         /* write register's data */
 131         err = i2c_master_send(client, buf, i);
 132         if (err != i) {
 133                 dev_err(&client->dev,
 134                         "%s: err=%d", __func__, err);
 135                 return -EIO;
 136         }
 137
 138         return 0;
 139 }
 140
 141 #ifdef CONFIG_RTC_INTF_DEV
 142 static int pcf2127_rtc_ioctl(struct device *dev,
 143                                 unsigned int cmd, unsigned long arg)
 144 {
 145         struct i2c_client *client = to_i2c_client(dev);
 146         unsigned char buf = PCF2127_REG_CTRL3;
 147         int touser;
 148         int ret;
 149
 150         switch (cmd) {
 151         case RTC_VL_READ:
 152                 ret = i2c_master_send(client, &buf, 1);
 153                 if (!ret)
 154                         ret = -EIO;
 155                 if (ret < 0)
 156                         return ret;
 157
 158                 ret = i2c_master_recv(client, &buf, 1);
 159                 if (!ret)
 160                         ret = -EIO;
 161                 if (ret < 0)
 162                         return ret;
 163
 164                 touser = buf & PCF2127_REG_CTRL3_BLF ? 1 : 0;
 165
 166                 if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
 167                         return -EFAULT;
 168                 return 0;
 169         default:
 170                 return -ENOIOCTLCMD;
 171         }
 172 }
 173 #else
 174 #define pcf2127_rtc_ioctl NULL
 175 #endif
 176
 177 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
 178 {
 179         return pcf2127_get_datetime(to_i2c_client(dev), tm);
 180 }
 181
 182 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
 183 {
 184         return pcf2127_set_datetime(to_i2c_client(dev), tm);
 185 }
 186
 187 static const struct rtc_class_ops pcf2127_rtc_ops = {
 188         .ioctl          = pcf2127_rtc_ioctl,
 189         .read_time      = pcf2127_rtc_read_time,
 190         .set_time       = pcf2127_rtc_set_time,
 191 };
 192
 193 static int pcf2127_probe(struct i2c_client *client,
 194                                 const struct i2c_device_id *id)
 195 {
 196         struct pcf2127 *pcf2127;
 197
 198         dev_dbg(&client->dev, "%s\n", __func__);
 199
 200         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 201                 return -ENODEV;
 202
 203         pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
 204                                 GFP_KERNEL);
 205         if (!pcf2127)
 206                 return -ENOMEM;
 207
 208         i2c_set_clientdata(client, pcf2127);
 209
 210         pcf2127->rtc = devm_rtc_device_register(&client->dev,
 211                                 pcf2127_driver.driver.name,
 212                                 &pcf2127_rtc_ops, THIS_MODULE);
 213
 214         return PTR_ERR_OR_ZERO(pcf2127->rtc);
 215 }
 216
 217 static const struct i2c_device_id pcf2127_id[] = {
 218         { "pcf2127", 0 },
 219         { }
 220 };
 221 MODULE_DEVICE_TABLE(i2c, pcf2127_id);
 222
 223 #ifdef CONFIG_OF
 224 static const struct of_device_id pcf2127_of_match[] = {
 225         { .compatible = "nxp,pcf2127" },
 226         {}
 227 };
 228 MODULE_DEVICE_TABLE(of, pcf2127_of_match);
 229 #endif
 230
 231 static struct i2c_driver pcf2127_driver = {
 232         .driver         = {
 233                 .name   = "rtc-pcf2127",
 234                 .of_match_table = of_match_ptr(pcf2127_of_match),
 235         },
 236         .probe          = pcf2127_probe,
 237         .id_table       = pcf2127_id,
 238 };
 239
 240 module_i2c_driver(pcf2127_driver);
 241
 242 MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
 243 MODULE_DESCRIPTION("NXP PCF2127 RTC driver");
 244 MODULE_LICENSE("GPL v2");