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 DRV_VERSION "0.0.1"
  24
  25 #define PCF2127_REG_CTRL1       (0x00)  /* Control Register 1 */
  26 #define PCF2127_REG_CTRL2       (0x01)  /* Control Register 2 */
  27 #define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
  28 #define PCF2127_REG_SC          (0x03)  /* datetime */
  29 #define PCF2127_REG_MN          (0x04)
  30 #define PCF2127_REG_HR          (0x05)
  31 #define PCF2127_REG_DM          (0x06)
  32 #define PCF2127_REG_DW          (0x07)
  33 #define PCF2127_REG_MO          (0x08)
  34 #define PCF2127_REG_YR          (0x09)
  35
  36 #define PCF2127_OSF             BIT(7)  /* Oscillator Fail flag */
  37
  38 static struct i2c_driver pcf2127_driver;
  39
  40 struct pcf2127 {
  41         struct rtc_device *rtc;
  42         int voltage_low; /* indicates if a low_voltage was detected */
  43         int oscillator_failed; /* OSF was detected and date is unreliable */
  44 };
  45
  46 /*
  47  * In the routines that deal directly with the pcf2127 hardware, we use
  48  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  49  */
  50 static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  51 {
  52         struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
  53         unsigned char buf[10] = { PCF2127_REG_CTRL1 };
  54
  55         /* read registers */
  56         if (i2c_master_send(client, buf, 1) != 1 ||
  57                 i2c_master_recv(client, buf, sizeof(buf)) != sizeof(buf)) {
  58                 dev_err(&client->dev, "%s: read error\n", __func__);
  59                 return -EIO;
  60         }
  61
  62         if (buf[PCF2127_REG_CTRL3] & 0x04) {
  63                 pcf2127->voltage_low = 1;
  64                 dev_info(&client->dev,
  65                         "low voltage detected, check/replace RTC battery.\n");
  66         }
  67
  68         if (buf[PCF2127_REG_SC] & PCF2127_OSF) {
  69                 /*
  70                  * no need clear the flag here,
  71                  * it will be cleared once the new date is saved
  72                  */
  73                 pcf2127->oscillator_failed = 1;
  74                 dev_warn(&client->dev,
  75                          "oscillator stop detected, date/time is not reliable\n");
  76                 return -EINVAL;
  77         }
  78
  79         dev_dbg(&client->dev,
  80                 "%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
  81                 "sec=%02x, min=%02x, hr=%02x, "
  82                 "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
  83                 __func__,
  84                 buf[0], buf[1], buf[2],
  85                 buf[3], buf[4], buf[5],
  86                 buf[6], buf[7], buf[8], buf[9]);
  87
  88
  89         tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
  90         tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
  91         tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
  92         tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
  93         tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
  94         tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
  95         tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
  96         if (tm->tm_year < 70)
  97                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  98
  99         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 100                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 101                 __func__,
 102                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 103                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 104
 105         return rtc_valid_tm(tm);
 106 }
 107
 108 static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 109 {
 110         struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
 111         unsigned char buf[8];
 112         int i = 0, err;
 113
 114         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 115                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 116                 __func__,
 117                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 118                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 119
 120         /* start register address */
 121         buf[i++] = PCF2127_REG_SC;
 122
 123         /* hours, minutes and seconds */
 124         buf[i++] = bin2bcd(tm->tm_sec); /* this will also clear OSF flag */
 125         buf[i++] = bin2bcd(tm->tm_min);
 126         buf[i++] = bin2bcd(tm->tm_hour);
 127         buf[i++] = bin2bcd(tm->tm_mday);
 128         buf[i++] = tm->tm_wday & 0x07;
 129
 130         /* month, 1 - 12 */
 131         buf[i++] = bin2bcd(tm->tm_mon + 1);
 132
 133         /* year */
 134         buf[i++] = bin2bcd(tm->tm_year % 100);
 135
 136         /* write register's data */
 137         err = i2c_master_send(client, buf, i);
 138         if (err != i) {
 139                 dev_err(&client->dev,
 140                         "%s: err=%d", __func__, err);
 141                 return -EIO;
 142         }
 143
 144         /* clear OSF flag in client data */
 145         pcf2127->oscillator_failed = 0;
 146
 147         return 0;
 148 }
 149
 150 #ifdef CONFIG_RTC_INTF_DEV
 151 static int pcf2127_rtc_ioctl(struct device *dev,
 152                                 unsigned int cmd, unsigned long arg)
 153 {
 154         struct pcf2127 *pcf2127 = i2c_get_clientdata(to_i2c_client(dev));
 155
 156         switch (cmd) {
 157         case RTC_VL_READ:
 158                 if (pcf2127->voltage_low)
 159                         dev_info(dev, "low voltage detected, check/replace battery\n");
 160                 if (pcf2127->oscillator_failed)
 161                         dev_info(dev, "oscillator stop detected, date/time is not reliable\n");
 162
 163                 if (copy_to_user((void __user *)arg, &pcf2127->voltage_low,
 164                                         sizeof(int)))
 165                         return -EFAULT;
 166                 return 0;
 167         default:
 168                 return -ENOIOCTLCMD;
 169         }
 170 }
 171 #else
 172 #define pcf2127_rtc_ioctl NULL
 173 #endif
 174
 175 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
 176 {
 177         return pcf2127_get_datetime(to_i2c_client(dev), tm);
 178 }
 179
 180 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
 181 {
 182         return pcf2127_set_datetime(to_i2c_client(dev), tm);
 183 }
 184
 185 static const struct rtc_class_ops pcf2127_rtc_ops = {
 186         .ioctl          = pcf2127_rtc_ioctl,
 187         .read_time      = pcf2127_rtc_read_time,
 188         .set_time       = pcf2127_rtc_set_time,
 189 };
 190
 191 static int pcf2127_probe(struct i2c_client *client,
 192                                 const struct i2c_device_id *id)
 193 {
 194         struct pcf2127 *pcf2127;
 195
 196         dev_dbg(&client->dev, "%s\n", __func__);
 197
 198         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 199                 return -ENODEV;
 200
 201         pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
 202                                 GFP_KERNEL);
 203         if (!pcf2127)
 204                 return -ENOMEM;
 205
 206         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 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");
 245 MODULE_VERSION(DRV_VERSION);