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 #include <linux/of.h>
  21 #include <linux/of_device.h>
  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_rtc_read_time(struct device *dev, struct rtc_time *tm)
 108 {
 109         struct i2c_client *client = to_i2c_client(dev);
 110         uint8_t buf[ISL12022_REG_INT + 1];
 111         int ret;
 112
 113         ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
 114         if (ret)
 115                 return ret;
 116
 117         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
 118                 dev_warn(&client->dev,
 119                          "voltage dropped below %u%%, "
 120                          "date and time is not reliable.\n",
 121                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
 122         }
 123
 124         dev_dbg(&client->dev,
 125                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 126                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
 127                 "sr=%02x, int=%02x",
 128                 __func__,
 129                 buf[ISL12022_REG_SC],
 130                 buf[ISL12022_REG_MN],
 131                 buf[ISL12022_REG_HR],
 132                 buf[ISL12022_REG_DT],
 133                 buf[ISL12022_REG_MO],
 134                 buf[ISL12022_REG_YR],
 135                 buf[ISL12022_REG_DW],
 136                 buf[ISL12022_REG_SR],
 137                 buf[ISL12022_REG_INT]);
 138
 139         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 140         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 141         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 142         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 143         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 144         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 145         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
 146
 147         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 148                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 149                 __func__,
 150                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 151                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 152
 153         return 0;
 154 }
 155
 156 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 157 {
 158         struct i2c_client *client = to_i2c_client(dev);
 159         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 160         size_t i;
 161         int ret;
 162         uint8_t buf[ISL12022_REG_DW + 1];
 163
 164         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 165                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 166                 __func__,
 167                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 168                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 169
 170         if (!isl12022->write_enabled) {
 171
 172                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 173                 if (ret)
 174                         return ret;
 175
 176                 /* Check if WRTC (write rtc enable) is set factory default is
 177                  * 0 (not set) */
 178                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 179                         dev_info(&client->dev,
 180                                  "init write enable and 24 hour format\n");
 181
 182                         /* Set the write enable bit. */
 183                         ret = isl12022_write_reg(client,
 184                                                  ISL12022_REG_INT,
 185                                                  buf[0] | ISL12022_INT_WRTC);
 186                         if (ret)
 187                                 return ret;
 188
 189                         /* Write to any RTC register to start RTC, we use the
 190                          * HR register, setting the MIL bit to use the 24 hour
 191                          * format. */
 192                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 193                                                  buf, 1);
 194                         if (ret)
 195                                 return ret;
 196
 197                         ret = isl12022_write_reg(client,
 198                                                  ISL12022_REG_HR,
 199                                                  buf[0] | ISL12022_HR_MIL);
 200                         if (ret)
 201                                 return ret;
 202                 }
 203
 204                 isl12022->write_enabled = true;
 205         }
 206
 207         /* hours, minutes and seconds */
 208         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 209         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 210         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 211
 212         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 213
 214         /* month, 1 - 12 */
 215         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 216
 217         /* year and century */
 218         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 219
 220         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 221
 222         /* write register's data */
 223         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 224                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 225                                          buf[ISL12022_REG_SC + i]);
 226                 if (ret)
 227                         return -EIO;
 228         }
 229
 230         return 0;
 231 }
 232
 233 static const struct rtc_class_ops isl12022_rtc_ops = {
 234         .read_time      = isl12022_rtc_read_time,
 235         .set_time       = isl12022_rtc_set_time,
 236 };
 237
 238 static int isl12022_probe(struct i2c_client *client,
 239                           const struct i2c_device_id *id)
 240 {
 241         struct isl12022 *isl12022;
 242
 243         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 244                 return -ENODEV;
 245
 246         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
 247                                 GFP_KERNEL);
 248         if (!isl12022)
 249                 return -ENOMEM;
 250
 251         i2c_set_clientdata(client, isl12022);
 252
 253         isl12022->rtc = devm_rtc_device_register(&client->dev,
 254                                         isl12022_driver.driver.name,
 255                                         &isl12022_rtc_ops, THIS_MODULE);
 256         return PTR_ERR_OR_ZERO(isl12022->rtc);
 257 }
 258
 259 #ifdef CONFIG_OF
 260 static const struct of_device_id isl12022_dt_match[] = {
 261         { .compatible = "isl,isl12022" }, /* for backward compat., don't use */
 262         { .compatible = "isil,isl12022" },
 263         { },
 264 };
 265 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
 266 #endif
 267
 268 static const struct i2c_device_id isl12022_id[] = {
 269         { "isl12022", 0 },
 270         { }
 271 };
 272 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 273
 274 static struct i2c_driver isl12022_driver = {
 275         .driver         = {
 276                 .name   = "rtc-isl12022",
 277 #ifdef CONFIG_OF
 278                 .of_match_table = of_match_ptr(isl12022_dt_match),
 279 #endif
 280         },
 281         .probe          = isl12022_probe,
 282         .id_table       = isl12022_id,
 283 };
 284
 285 module_i2c_driver(isl12022_driver);
 286
 287 MODULE_AUTHOR("roman.fietze@telemotive.de");
 288 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 289 MODULE_LICENSE("GPL");