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
  19 #define DRV_VERSION "0.1"
  20
  21 /* ISL register offsets */
  22 #define ISL12022_REG_SC         0x00
  23 #define ISL12022_REG_MN         0x01
  24 #define ISL12022_REG_HR         0x02
  25 #define ISL12022_REG_DT         0x03
  26 #define ISL12022_REG_MO         0x04
  27 #define ISL12022_REG_YR         0x05
  28 #define ISL12022_REG_DW         0x06
  29
  30 #define ISL12022_REG_SR         0x07
  31 #define ISL12022_REG_INT        0x08
  32
  33 /* ISL register bits */
  34 #define ISL12022_HR_MIL         (1 << 7)        /* military or 24 hour time */
  35
  36 #define ISL12022_SR_LBAT85      (1 << 2)
  37 #define ISL12022_SR_LBAT75      (1 << 1)
  38
  39 #define ISL12022_INT_WRTC       (1 << 6)
  40
  41
  42 static struct i2c_driver isl12022_driver;
  43
  44 struct isl12022 {
  45         struct rtc_device *rtc;
  46
  47         bool write_enabled;     /* true if write enable is set */
  48 };
  49
  50
  51 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
  52                               uint8_t *data, size_t n)
  53 {
  54         struct i2c_msg msgs[] = {
  55                 {
  56                         .addr   = client->addr,
  57                         .flags  = 0,
  58                         .len    = 1,
  59                         .buf    = data
  60                 },              /* setup read ptr */
  61                 {
  62                         .addr   = client->addr,
  63                         .flags  = I2C_M_RD,
  64                         .len    = n,
  65                         .buf    = data
  66                 }
  67         };
  68
  69         int ret;
  70
  71         data[0] = reg;
  72         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  73         if (ret != ARRAY_SIZE(msgs)) {
  74                 dev_err(&client->dev, "%s: read error, ret=%d\n",
  75                         __func__, ret);
  76                 return -EIO;
  77         }
  78
  79         return 0;
  80 }
  81
  82
  83 static int isl12022_write_reg(struct i2c_client *client,
  84                               uint8_t reg, uint8_t val)
  85 {
  86         uint8_t data[2] = { reg, val };
  87         int err;
  88
  89         err = i2c_master_send(client, data, sizeof(data));
  90         if (err != sizeof(data)) {
  91                 dev_err(&client->dev,
  92                         "%s: err=%d addr=%02x, data=%02x\n",
  93                         __func__, err, data[0], data[1]);
  94                 return -EIO;
  95         }
  96
  97         return 0;
  98 }
  99
 100
 101 /*
 102  * In the routines that deal directly with the isl12022 hardware, we use
 103  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 104  */
 105 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 106 {
 107         uint8_t buf[ISL12022_REG_INT + 1];
 108         int ret;
 109
 110         ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
 111         if (ret)
 112                 return ret;
 113
 114         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
 115                 dev_warn(&client->dev,
 116                          "voltage dropped below %u%%, "
 117                          "date and time is not reliable.\n",
 118                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
 119         }
 120
 121         dev_dbg(&client->dev,
 122                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 123                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
 124                 "sr=%02x, int=%02x",
 125                 __func__,
 126                 buf[ISL12022_REG_SC],
 127                 buf[ISL12022_REG_MN],
 128                 buf[ISL12022_REG_HR],
 129                 buf[ISL12022_REG_DT],
 130                 buf[ISL12022_REG_MO],
 131                 buf[ISL12022_REG_YR],
 132                 buf[ISL12022_REG_DW],
 133                 buf[ISL12022_REG_SR],
 134                 buf[ISL12022_REG_INT]);
 135
 136         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 137         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 138         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 139         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 140         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 141         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 142         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
 143
 144         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 145                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 146                 __func__,
 147                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 148                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 149
 150         /* The clock can give out invalid datetime, but we cannot return
 151          * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
 152         if (rtc_valid_tm(tm) < 0)
 153                 dev_err(&client->dev, "retrieved date and time is invalid.\n");
 154
 155         return 0;
 156 }
 157
 158 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 159 {
 160         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 161         size_t i;
 162         int ret;
 163         uint8_t buf[ISL12022_REG_DW + 1];
 164
 165         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 166                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 167                 __func__,
 168                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 169                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 170
 171         if (!isl12022->write_enabled) {
 172
 173                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 174                 if (ret)
 175                         return ret;
 176
 177                 /* Check if WRTC (write rtc enable) is set factory default is
 178                  * 0 (not set) */
 179                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 180                         dev_info(&client->dev,
 181                                  "init write enable and 24 hour format\n");
 182
 183                         /* Set the write enable bit. */
 184                         ret = isl12022_write_reg(client,
 185                                                  ISL12022_REG_INT,
 186                                                  buf[0] | ISL12022_INT_WRTC);
 187                         if (ret)
 188                                 return ret;
 189
 190                         /* Write to any RTC register to start RTC, we use the
 191                          * HR register, setting the MIL bit to use the 24 hour
 192                          * format. */
 193                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 194                                                  buf, 1);
 195                         if (ret)
 196                                 return ret;
 197
 198                         ret = isl12022_write_reg(client,
 199                                                  ISL12022_REG_HR,
 200                                                  buf[0] | ISL12022_HR_MIL);
 201                         if (ret)
 202                                 return ret;
 203                 }
 204
 205                 isl12022->write_enabled = 1;
 206         }
 207
 208         /* hours, minutes and seconds */
 209         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 210         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 211         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 212
 213         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 214
 215         /* month, 1 - 12 */
 216         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 217
 218         /* year and century */
 219         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 220
 221         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 222
 223         /* write register's data */
 224         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 225                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 226                                          buf[ISL12022_REG_SC + i]);
 227                 if (ret)
 228                         return -EIO;
 229         };
 230
 231         return 0;
 232 }
 233
 234 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 235 {
 236         return isl12022_get_datetime(to_i2c_client(dev), tm);
 237 }
 238
 239 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 240 {
 241         return isl12022_set_datetime(to_i2c_client(dev), tm);
 242 }
 243
 244 static const struct rtc_class_ops isl12022_rtc_ops = {
 245         .read_time      = isl12022_rtc_read_time,
 246         .set_time       = isl12022_rtc_set_time,
 247 };
 248
 249 static int isl12022_probe(struct i2c_client *client,
 250                           const struct i2c_device_id *id)
 251 {
 252         struct isl12022 *isl12022;
 253
 254         int ret = 0;
 255
 256         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 257                 return -ENODEV;
 258
 259         isl12022 = kzalloc(sizeof(struct isl12022), GFP_KERNEL);
 260         if (!isl12022)
 261                 return -ENOMEM;
 262
 263         dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 264
 265         i2c_set_clientdata(client, isl12022);
 266
 267         isl12022->rtc = rtc_device_register(isl12022_driver.driver.name,
 268                                             &client->dev,
 269                                             &isl12022_rtc_ops,
 270                                             THIS_MODULE);
 271
 272         if (IS_ERR(isl12022->rtc)) {
 273                 ret = PTR_ERR(isl12022->rtc);
 274                 goto exit_kfree;
 275         }
 276
 277         return 0;
 278
 279 exit_kfree:
 280         kfree(isl12022);
 281
 282         return ret;
 283 }
 284
 285 static int isl12022_remove(struct i2c_client *client)
 286 {
 287         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 288
 289         rtc_device_unregister(isl12022->rtc);
 290         kfree(isl12022);
 291
 292         return 0;
 293 }
 294
 295 static const struct i2c_device_id isl12022_id[] = {
 296         { "isl12022", 0 },
 297         { "rtc8564", 0 },
 298         { }
 299 };
 300 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 301
 302 static struct i2c_driver isl12022_driver = {
 303         .driver         = {
 304                 .name   = "rtc-isl12022",
 305         },
 306         .probe          = isl12022_probe,
 307         .remove         = isl12022_remove,
 308         .id_table       = isl12022_id,
 309 };
 310
 311 static int __init isl12022_init(void)
 312 {
 313         return i2c_add_driver(&isl12022_driver);
 314 }
 315
 316 static void __exit isl12022_exit(void)
 317 {
 318         i2c_del_driver(&isl12022_driver);
 319 }
 320
 321 module_init(isl12022_init);
 322 module_exit(isl12022_exit);
 323
 324 MODULE_AUTHOR("roman.fietze@telemotive.de");
 325 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 326 MODULE_LICENSE("GPL");
 327 MODULE_VERSION(DRV_VERSION);