drivers/rtc/rtc-isl12022.c

   1 /*
   2  * An I2C driver for the Intersil ISL 12022
   3  *
   4  * Author: Roman Fietze <roman.fietze@telemotive.de>
   5  *
   6  * Based on the Philips PCF8563 RTC
   7  * by Alessandro Zummo <a.zummo@towertech.it>.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version
  11  * 2 as published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/i2c.h>
  15 #include <linux/bcd.h>
  16 #include <linux/rtc.h>
  17 #include <linux/slab.h>
  18 #include <linux/module.h>
  19 #include <linux/err.h>
  20
  21 #define DRV_VERSION "0.1"
  22
  23 /* ISL register offsets */
  24 #define ISL12022_REG_SC         0x00
  25 #define ISL12022_REG_MN         0x01
  26 #define ISL12022_REG_HR         0x02
  27 #define ISL12022_REG_DT         0x03
  28 #define ISL12022_REG_MO         0x04
  29 #define ISL12022_REG_YR         0x05
  30 #define ISL12022_REG_DW         0x06
  31
  32 #define ISL12022_REG_SR         0x07
  33 #define ISL12022_REG_INT        0x08
  34
  35 /* ISL register bits */
  36 #define ISL12022_HR_MIL         (1 << 7)        /* military or 24 hour time */
  37
  38 #define ISL12022_SR_LBAT85      (1 << 2)
  39 #define ISL12022_SR_LBAT75      (1 << 1)
  40
  41 #define ISL12022_INT_WRTC       (1 << 6)
  42
  43
  44 static struct i2c_driver isl12022_driver;
  45
  46 struct isl12022 {
  47         struct rtc_device *rtc;
  48
  49         bool write_enabled;     /* true if write enable is set */
  50 };
  51
  52
  53 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
  54                               uint8_t *data, size_t n)
  55 {
  56         struct i2c_msg msgs[] = {
  57                 {
  58                         .addr   = client->addr,
  59                         .flags  = 0,
  60                         .len    = 1,
  61                         .buf    = data
  62                 },              /* setup read ptr */
  63                 {
  64                         .addr   = client->addr,
  65                         .flags  = I2C_M_RD,
  66                         .len    = n,
  67                         .buf    = data
  68                 }
  69         };
  70
  71         int ret;
  72
  73         data[0] = reg;
  74         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  75         if (ret != ARRAY_SIZE(msgs)) {
  76                 dev_err(&client->dev, "%s: read error, ret=%d\n",
  77                         __func__, ret);
  78                 return -EIO;
  79         }
  80
  81         return 0;
  82 }
  83
  84
  85 static int isl12022_write_reg(struct i2c_client *client,
  86                               uint8_t reg, uint8_t val)
  87 {
  88         uint8_t data[2] = { reg, val };
  89         int err;
  90
  91         err = i2c_master_send(client, data, sizeof(data));
  92         if (err != sizeof(data)) {
  93                 dev_err(&client->dev,
  94                         "%s: err=%d addr=%02x, data=%02x\n",
  95                         __func__, err, data[0], data[1]);
  96                 return -EIO;
  97         }
  98
  99         return 0;
 100 }
 101
 102
 103 /*
 104  * In the routines that deal directly with the isl12022 hardware, we use
 105  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 106  */
 107 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 108 {
 109         uint8_t buf[ISL12022_REG_INT + 1];
 110         int ret;
 111
 112         ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
 113         if (ret)
 114                 return ret;
 115
 116         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
 117                 dev_warn(&client->dev,
 118                          "voltage dropped below %u%%, "
 119                          "date and time is not reliable.\n",
 120                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
 121         }
 122
 123         dev_dbg(&client->dev,
 124                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 125                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
 126                 "sr=%02x, int=%02x",
 127                 __func__,
 128                 buf[ISL12022_REG_SC],
 129                 buf[ISL12022_REG_MN],
 130                 buf[ISL12022_REG_HR],
 131                 buf[ISL12022_REG_DT],
 132                 buf[ISL12022_REG_MO],
 133                 buf[ISL12022_REG_YR],
 134                 buf[ISL12022_REG_DW],
 135                 buf[ISL12022_REG_SR],
 136                 buf[ISL12022_REG_INT]);
 137
 138         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 139         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 140         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 141         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 142         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 143         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 144         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
 145
 146         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 147                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 148                 __func__,
 149                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 150                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 151
 152         /* The clock can give out invalid datetime, but we cannot return
 153          * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
 154         if (rtc_valid_tm(tm) < 0)
 155                 dev_err(&client->dev, "retrieved date and time is invalid.\n");
 156
 157         return 0;
 158 }
 159
 160 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 161 {
 162         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 163         size_t i;
 164         int ret;
 165         uint8_t buf[ISL12022_REG_DW + 1];
 166
 167         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 168                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 169                 __func__,
 170                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 171                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 172
 173         if (!isl12022->write_enabled) {
 174
 175                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 176                 if (ret)
 177                         return ret;
 178
 179                 /* Check if WRTC (write rtc enable) is set factory default is
 180                  * 0 (not set) */
 181                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 182                         dev_info(&client->dev,
 183                                  "init write enable and 24 hour format\n");
 184
 185                         /* Set the write enable bit. */
 186                         ret = isl12022_write_reg(client,
 187                                                  ISL12022_REG_INT,
 188                                                  buf[0] | ISL12022_INT_WRTC);
 189                         if (ret)
 190                                 return ret;
 191
 192                         /* Write to any RTC register to start RTC, we use the
 193                          * HR register, setting the MIL bit to use the 24 hour
 194                          * format. */
 195                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 196                                                  buf, 1);
 197                         if (ret)
 198                                 return ret;
 199
 200                         ret = isl12022_write_reg(client,
 201                                                  ISL12022_REG_HR,
 202                                                  buf[0] | ISL12022_HR_MIL);
 203                         if (ret)
 204                                 return ret;
 205                 }
 206
 207                 isl12022->write_enabled = 1;
 208         }
 209
 210         /* hours, minutes and seconds */
 211         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 212         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 213         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 214
 215         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 216
 217         /* month, 1 - 12 */
 218         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 219
 220         /* year and century */
 221         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 222
 223         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 224
 225         /* write register's data */
 226         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 227                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 228                                          buf[ISL12022_REG_SC + i]);
 229                 if (ret)
 230                         return -EIO;
 231         }
 232
 233         return 0;
 234 }
 235
 236 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 237 {
 238         return isl12022_get_datetime(to_i2c_client(dev), tm);
 239 }
 240
 241 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 242 {
 243         return isl12022_set_datetime(to_i2c_client(dev), tm);
 244 }
 245
 246 static const struct rtc_class_ops isl12022_rtc_ops = {
 247         .read_time      = isl12022_rtc_read_time,
 248         .set_time       = isl12022_rtc_set_time,
 249 };
 250
 251 static int isl12022_probe(struct i2c_client *client,
 252                           const struct i2c_device_id *id)
 253 {
 254         struct isl12022 *isl12022;
 255
 256         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 257                 return -ENODEV;
 258
 259         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
 260                                 GFP_KERNEL);
 261         if (!isl12022)
 262                 return -ENOMEM;
 263
 264         dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 265
 266         i2c_set_clientdata(client, isl12022);
 267
 268         isl12022->rtc = devm_rtc_device_register(&client->dev,
 269                                         isl12022_driver.driver.name,
 270                                         &isl12022_rtc_ops, THIS_MODULE);
 271         return PTR_ERR_OR_ZERO(isl12022->rtc);
 272 }
 273
 274 static const struct i2c_device_id isl12022_id[] = {
 275         { "isl12022", 0 },
 276         { }
 277 };
 278 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 279
 280 static struct i2c_driver isl12022_driver = {
 281         .driver         = {
 282                 .name   = "rtc-isl12022",
 283         },
 284         .probe          = isl12022_probe,
 285         .id_table       = isl12022_id,
 286 };
 287
 288 module_i2c_driver(isl12022_driver);
 289
 290 MODULE_AUTHOR("roman.fietze@telemotive.de");
 291 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 292 MODULE_LICENSE("GPL");
 293 MODULE_VERSION(DRV_VERSION);