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
  28 #define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
  29 #define PCF2127_REG_CTRL3_BLF           BIT(2)
  30
  31 #define PCF2127_REG_SC          (0x03)  /* datetime */
  32 #define PCF2127_REG_MN          (0x04)
  33 #define PCF2127_REG_HR          (0x05)
  34 #define PCF2127_REG_DM          (0x06)
  35 #define PCF2127_REG_DW          (0x07)
  36 #define PCF2127_REG_MO          (0x08)
  37 #define PCF2127_REG_YR          (0x09)
  38
  39 #define PCF2127_OSF             BIT(7)  /* Oscillator Fail flag */
  40
  41 static struct i2c_driver pcf2127_driver;
  42
  43 struct pcf2127 {
  44         struct rtc_device *rtc;
  45 };
  46
  47 /*
  48  * In the routines that deal directly with the pcf2127 hardware, we use
  49  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  50  */
  51 static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  52 {
  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] & PCF2127_REG_CTRL3_BLF)
  63                 dev_info(&client->dev,
  64                         "low voltage detected, check/replace RTC battery.\n");
  65
  66         if (buf[PCF2127_REG_SC] & PCF2127_OSF) {
  67                 /*
  68                  * no need clear the flag here,
  69                  * it will be cleared once the new date is saved
  70                  */
  71                 dev_warn(&client->dev,
  72                          "oscillator stop detected, date/time is not reliable\n");
  73                 return -EINVAL;
  74         }
  75
  76         dev_dbg(&client->dev,
  77                 "%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
  78                 "sec=%02x, min=%02x, hr=%02x, "
  79                 "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
  80                 __func__,
  81                 buf[0], buf[1], buf[2],
  82                 buf[3], buf[4], buf[5],
  83                 buf[6], buf[7], buf[8], buf[9]);
  84
  85
  86         tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
  87         tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
  88         tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
  89         tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
  90         tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
  91         tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
  92         tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
  93         if (tm->tm_year < 70)
  94                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
  95
  96         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  97                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  98                 __func__,
  99                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 100                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 101
 102         return rtc_valid_tm(tm);
 103 }
 104
 105 static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 106 {
 107         unsigned char buf[8];
 108         int i = 0, err;
 109
 110         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 111                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 112                 __func__,
 113                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 114                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 115
 116         /* start register address */
 117         buf[i++] = PCF2127_REG_SC;
 118
 119         /* hours, minutes and seconds */
 120         buf[i++] = bin2bcd(tm->tm_sec); /* this will also clear OSF flag */
 121         buf[i++] = bin2bcd(tm->tm_min);
 122         buf[i++] = bin2bcd(tm->tm_hour);
 123         buf[i++] = bin2bcd(tm->tm_mday);
 124         buf[i++] = tm->tm_wday & 0x07;
 125
 126         /* month, 1 - 12 */
 127         buf[i++] = bin2bcd(tm->tm_mon + 1);
 128
 129         /* year */
 130         buf[i++] = bin2bcd(tm->tm_year % 100);
 131
 132         /* write register's data */
 133         err = i2c_master_send(client, buf, i);
 134         if (err != i) {
 135                 dev_err(&client->dev,
 136                         "%s: err=%d", __func__, err);
 137                 return -EIO;
 138         }
 139
 140         return 0;
 141 }
 142
 143 #ifdef CONFIG_RTC_INTF_DEV
 144 static int pcf2127_rtc_ioctl(struct device *dev,
 145                                 unsigned int cmd, unsigned long arg)
 146 {
 147         struct i2c_client *client = to_i2c_client(dev);
 148         unsigned char buf = PCF2127_REG_CTRL3;
 149         int touser;
 150         int ret;
 151
 152         switch (cmd) {
 153         case RTC_VL_READ:
 154                 ret = i2c_master_send(client, &buf, 1);
 155                 if (!ret)
 156                         ret = -EIO;
 157                 if (ret < 0)
 158                         return ret;
 159
 160                 ret = i2c_master_recv(client, &buf, 1);
 161                 if (!ret)
 162                         ret = -EIO;
 163                 if (ret < 0)
 164                         return ret;
 165
 166                 touser = buf & PCF2127_REG_CTRL3_BLF ? 1 : 0;
 167
 168                 if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
 169                         return -EFAULT;
 170                 return 0;
 171         default:
 172                 return -ENOIOCTLCMD;
 173         }
 174 }
 175 #else
 176 #define pcf2127_rtc_ioctl NULL
 177 #endif
 178
 179 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
 180 {
 181         return pcf2127_get_datetime(to_i2c_client(dev), tm);
 182 }
 183
 184 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
 185 {
 186         return pcf2127_set_datetime(to_i2c_client(dev), tm);
 187 }
 188
 189 static const struct rtc_class_ops pcf2127_rtc_ops = {
 190         .ioctl          = pcf2127_rtc_ioctl,
 191         .read_time      = pcf2127_rtc_read_time,
 192         .set_time       = pcf2127_rtc_set_time,
 193 };
 194
 195 static int pcf2127_probe(struct i2c_client *client,
 196                                 const struct i2c_device_id *id)
 197 {
 198         struct pcf2127 *pcf2127;
 199
 200         dev_dbg(&client->dev, "%s\n", __func__);
 201
 202         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 203                 return -ENODEV;
 204
 205         pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
 206                                 GFP_KERNEL);
 207         if (!pcf2127)
 208                 return -ENOMEM;
 209
 210         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 211
 212         i2c_set_clientdata(client, pcf2127);
 213
 214         pcf2127->rtc = devm_rtc_device_register(&client->dev,
 215                                 pcf2127_driver.driver.name,
 216                                 &pcf2127_rtc_ops, THIS_MODULE);
 217
 218         return PTR_ERR_OR_ZERO(pcf2127->rtc);
 219 }
 220
 221 static const struct i2c_device_id pcf2127_id[] = {
 222         { "pcf2127", 0 },
 223         { }
 224 };
 225 MODULE_DEVICE_TABLE(i2c, pcf2127_id);
 226
 227 #ifdef CONFIG_OF
 228 static const struct of_device_id pcf2127_of_match[] = {
 229         { .compatible = "nxp,pcf2127" },
 230         {}
 231 };
 232 MODULE_DEVICE_TABLE(of, pcf2127_of_match);
 233 #endif
 234
 235 static struct i2c_driver pcf2127_driver = {
 236         .driver         = {
 237                 .name   = "rtc-pcf2127",
 238                 .of_match_table = of_match_ptr(pcf2127_of_match),
 239         },
 240         .probe          = pcf2127_probe,
 241         .id_table       = pcf2127_id,
 242 };
 243
 244 module_i2c_driver(pcf2127_driver);
 245
 246 MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
 247 MODULE_DESCRIPTION("NXP PCF2127 RTC driver");
 248 MODULE_LICENSE("GPL v2");
 249 MODULE_VERSION(DRV_VERSION);