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 static struct i2c_driver pcf2127_driver;
  37
  38 struct pcf2127 {
  39         struct rtc_device *rtc;
  40         int voltage_low; /* indicates if a low_voltage was detected */
  41 };
  42
  43 /*
  44  * In the routines that deal directly with the pcf2127 hardware, we use
  45  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  46  */
  47 static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  48 {
  49         struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
  50         unsigned char buf[10] = { PCF2127_REG_CTRL1 };
  51
  52         /* read registers */
  53         if (i2c_master_send(client, buf, 1) != 1 ||
  54                 i2c_master_recv(client, buf, sizeof(buf)) != sizeof(buf)) {
  55                 dev_err(&client->dev, "%s: read error\n", __func__);
  56                 return -EIO;
  57         }
  58
  59         if (buf[PCF2127_REG_CTRL3] & 0x04) {
  60                 pcf2127->voltage_low = 1;
  61                 dev_info(&client->dev,
  62                         "low voltage detected, date/time is not reliable.\n");
  63         }
  64
  65         dev_dbg(&client->dev,
  66                 "%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
  67                 "sec=%02x, min=%02x, hr=%02x, "
  68                 "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
  69                 __func__,
  70                 buf[0], buf[1], buf[2],
  71                 buf[3], buf[4], buf[5],
  72                 buf[6], buf[7], buf[8], buf[9]);
  73
  74
  75         tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
  76         tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
  77         tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
  78         tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
  79         tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
  80         tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
  81         tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
  82         if (tm->tm_year < 70)
  83                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  84
  85         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  86                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  87                 __func__,
  88                 tm->tm_sec, tm->tm_min, tm->tm_hour,
  89                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  90
  91         /* the clock can give out invalid datetime, but we cannot return
  92          * -EINVAL otherwise hwclock will refuse to set the time on bootup.
  93          */
  94         if (rtc_valid_tm(tm) < 0)
  95                 dev_err(&client->dev, "retrieved date/time is not valid.\n");
  96
  97         return 0;
  98 }
  99
 100 static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 101 {
 102         unsigned char buf[8];
 103         int i = 0, err;
 104
 105         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 106                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 107                 __func__,
 108                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 109                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 110
 111         /* start register address */
 112         buf[i++] = PCF2127_REG_SC;
 113
 114         /* hours, minutes and seconds */
 115         buf[i++] = bin2bcd(tm->tm_sec);
 116         buf[i++] = bin2bcd(tm->tm_min);
 117         buf[i++] = bin2bcd(tm->tm_hour);
 118         buf[i++] = bin2bcd(tm->tm_mday);
 119         buf[i++] = tm->tm_wday & 0x07;
 120
 121         /* month, 1 - 12 */
 122         buf[i++] = bin2bcd(tm->tm_mon + 1);
 123
 124         /* year */
 125         buf[i++] = bin2bcd(tm->tm_year % 100);
 126
 127         /* write register's data */
 128         err = i2c_master_send(client, buf, i);
 129         if (err != i) {
 130                 dev_err(&client->dev,
 131                         "%s: err=%d", __func__, err);
 132                 return -EIO;
 133         }
 134
 135         return 0;
 136 }
 137
 138 #ifdef CONFIG_RTC_INTF_DEV
 139 static int pcf2127_rtc_ioctl(struct device *dev,
 140                                 unsigned int cmd, unsigned long arg)
 141 {
 142         struct pcf2127 *pcf2127 = i2c_get_clientdata(to_i2c_client(dev));
 143
 144         switch (cmd) {
 145         case RTC_VL_READ:
 146                 if (pcf2127->voltage_low)
 147                         dev_info(dev, "low voltage detected, date/time is not reliable.\n");
 148
 149                 if (copy_to_user((void __user *)arg, &pcf2127->voltage_low,
 150                                         sizeof(int)))
 151                         return -EFAULT;
 152                 return 0;
 153         default:
 154                 return -ENOIOCTLCMD;
 155         }
 156 }
 157 #else
 158 #define pcf2127_rtc_ioctl NULL
 159 #endif
 160
 161 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
 162 {
 163         return pcf2127_get_datetime(to_i2c_client(dev), tm);
 164 }
 165
 166 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
 167 {
 168         return pcf2127_set_datetime(to_i2c_client(dev), tm);
 169 }
 170
 171 static const struct rtc_class_ops pcf2127_rtc_ops = {
 172         .ioctl          = pcf2127_rtc_ioctl,
 173         .read_time      = pcf2127_rtc_read_time,
 174         .set_time       = pcf2127_rtc_set_time,
 175 };
 176
 177 static int pcf2127_probe(struct i2c_client *client,
 178                                 const struct i2c_device_id *id)
 179 {
 180         struct pcf2127 *pcf2127;
 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         pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
 188                                 GFP_KERNEL);
 189         if (!pcf2127)
 190                 return -ENOMEM;
 191
 192         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 193
 194         i2c_set_clientdata(client, pcf2127);
 195
 196         pcf2127->rtc = devm_rtc_device_register(&client->dev,
 197                                 pcf2127_driver.driver.name,
 198                                 &pcf2127_rtc_ops, THIS_MODULE);
 199
 200         return PTR_ERR_OR_ZERO(pcf2127->rtc);
 201 }
 202
 203 static const struct i2c_device_id pcf2127_id[] = {
 204         { "pcf2127", 0 },
 205         { }
 206 };
 207 MODULE_DEVICE_TABLE(i2c, pcf2127_id);
 208
 209 #ifdef CONFIG_OF
 210 static const struct of_device_id pcf2127_of_match[] = {
 211         { .compatible = "nxp,pcf2127" },
 212         {}
 213 };
 214 MODULE_DEVICE_TABLE(of, pcf2127_of_match);
 215 #endif
 216
 217 static struct i2c_driver pcf2127_driver = {
 218         .driver         = {
 219                 .name   = "rtc-pcf2127",
 220                 .owner  = THIS_MODULE,
 221                 .of_match_table = of_match_ptr(pcf2127_of_match),
 222         },
 223         .probe          = pcf2127_probe,
 224         .id_table       = pcf2127_id,
 225 };
 226
 227 module_i2c_driver(pcf2127_driver);
 228
 229 MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
 230 MODULE_DESCRIPTION("NXP PCF2127 RTC driver");
 231 MODULE_LICENSE("GPL");
 232 MODULE_VERSION(DRV_VERSION);