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 #define DRV_VERSION "0.1"
  24
  25 /* ISL register offsets */
  26 #define ISL12022_REG_SC         0x00
  27 #define ISL12022_REG_MN         0x01
  28 #define ISL12022_REG_HR         0x02
  29 #define ISL12022_REG_DT         0x03
  30 #define ISL12022_REG_MO         0x04
  31 #define ISL12022_REG_YR         0x05
  32 #define ISL12022_REG_DW         0x06
  33
  34 #define ISL12022_REG_SR         0x07
  35 #define ISL12022_REG_INT        0x08
  36
  37 /* ISL register bits */
  38 #define ISL12022_HR_MIL         (1 << 7)        /* military or 24 hour time */
  39
  40 #define ISL12022_SR_LBAT85      (1 << 2)
  41 #define ISL12022_SR_LBAT75      (1 << 1)
  42
  43 #define ISL12022_INT_WRTC       (1 << 6)
  44
  45
  46 static struct i2c_driver isl12022_driver;
  47
  48 struct isl12022 {
  49         struct rtc_device *rtc;
  50
  51         bool write_enabled;     /* true if write enable is set */
  52 };
  53
  54
  55 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
  56                               uint8_t *data, size_t n)
  57 {
  58         struct i2c_msg msgs[] = {
  59                 {
  60                         .addr   = client->addr,
  61                         .flags  = 0,
  62                         .len    = 1,
  63                         .buf    = data
  64                 },              /* setup read ptr */
  65                 {
  66                         .addr   = client->addr,
  67                         .flags  = I2C_M_RD,
  68                         .len    = n,
  69                         .buf    = data
  70                 }
  71         };
  72
  73         int ret;
  74
  75         data[0] = reg;
  76         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  77         if (ret != ARRAY_SIZE(msgs)) {
  78                 dev_err(&client->dev, "%s: read error, ret=%d\n",
  79                         __func__, ret);
  80                 return -EIO;
  81         }
  82
  83         return 0;
  84 }
  85
  86
  87 static int isl12022_write_reg(struct i2c_client *client,
  88                               uint8_t reg, uint8_t val)
  89 {
  90         uint8_t data[2] = { reg, val };
  91         int err;
  92
  93         err = i2c_master_send(client, data, sizeof(data));
  94         if (err != sizeof(data)) {
  95                 dev_err(&client->dev,
  96                         "%s: err=%d addr=%02x, data=%02x\n",
  97                         __func__, err, data[0], data[1]);
  98                 return -EIO;
  99         }
 100
 101         return 0;
 102 }
 103
 104
 105 /*
 106  * In the routines that deal directly with the isl12022 hardware, we use
 107  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 108  */
 109 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 110 {
 111         uint8_t buf[ISL12022_REG_INT + 1];
 112         int ret;
 113
 114         ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
 115         if (ret)
 116                 return ret;
 117
 118         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
 119                 dev_warn(&client->dev,
 120                          "voltage dropped below %u%%, "
 121                          "date and time is not reliable.\n",
 122                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
 123         }
 124
 125         dev_dbg(&client->dev,
 126                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 127                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
 128                 "sr=%02x, int=%02x",
 129                 __func__,
 130                 buf[ISL12022_REG_SC],
 131                 buf[ISL12022_REG_MN],
 132                 buf[ISL12022_REG_HR],
 133                 buf[ISL12022_REG_DT],
 134                 buf[ISL12022_REG_MO],
 135                 buf[ISL12022_REG_YR],
 136                 buf[ISL12022_REG_DW],
 137                 buf[ISL12022_REG_SR],
 138                 buf[ISL12022_REG_INT]);
 139
 140         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 141         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 142         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 143         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 144         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 145         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 146         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
 147
 148         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 149                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 150                 __func__,
 151                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 152                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 153
 154         /* The clock can give out invalid datetime, but we cannot return
 155          * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
 156         if (rtc_valid_tm(tm) < 0)
 157                 dev_err(&client->dev, "retrieved date and time is invalid.\n");
 158
 159         return 0;
 160 }
 161
 162 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 163 {
 164         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 165         size_t i;
 166         int ret;
 167         uint8_t buf[ISL12022_REG_DW + 1];
 168
 169         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 170                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 171                 __func__,
 172                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 173                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 174
 175         if (!isl12022->write_enabled) {
 176
 177                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 178                 if (ret)
 179                         return ret;
 180
 181                 /* Check if WRTC (write rtc enable) is set factory default is
 182                  * 0 (not set) */
 183                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 184                         dev_info(&client->dev,
 185                                  "init write enable and 24 hour format\n");
 186
 187                         /* Set the write enable bit. */
 188                         ret = isl12022_write_reg(client,
 189                                                  ISL12022_REG_INT,
 190                                                  buf[0] | ISL12022_INT_WRTC);
 191                         if (ret)
 192                                 return ret;
 193
 194                         /* Write to any RTC register to start RTC, we use the
 195                          * HR register, setting the MIL bit to use the 24 hour
 196                          * format. */
 197                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 198                                                  buf, 1);
 199                         if (ret)
 200                                 return ret;
 201
 202                         ret = isl12022_write_reg(client,
 203                                                  ISL12022_REG_HR,
 204                                                  buf[0] | ISL12022_HR_MIL);
 205                         if (ret)
 206                                 return ret;
 207                 }
 208
 209                 isl12022->write_enabled = 1;
 210         }
 211
 212         /* hours, minutes and seconds */
 213         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 214         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 215         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 216
 217         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 218
 219         /* month, 1 - 12 */
 220         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 221
 222         /* year and century */
 223         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 224
 225         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 226
 227         /* write register's data */
 228         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 229                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 230                                          buf[ISL12022_REG_SC + i]);
 231                 if (ret)
 232                         return -EIO;
 233         }
 234
 235         return 0;
 236 }
 237
 238 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 239 {
 240         return isl12022_get_datetime(to_i2c_client(dev), tm);
 241 }
 242
 243 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 244 {
 245         return isl12022_set_datetime(to_i2c_client(dev), tm);
 246 }
 247
 248 static const struct rtc_class_ops isl12022_rtc_ops = {
 249         .read_time      = isl12022_rtc_read_time,
 250         .set_time       = isl12022_rtc_set_time,
 251 };
 252
 253 static int isl12022_probe(struct i2c_client *client,
 254                           const struct i2c_device_id *id)
 255 {
 256         struct isl12022 *isl12022;
 257
 258         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 259                 return -ENODEV;
 260
 261         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
 262                                 GFP_KERNEL);
 263         if (!isl12022)
 264                 return -ENOMEM;
 265
 266         dev_dbg(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 267
 268         i2c_set_clientdata(client, isl12022);
 269
 270         isl12022->rtc = devm_rtc_device_register(&client->dev,
 271                                         isl12022_driver.driver.name,
 272                                         &isl12022_rtc_ops, THIS_MODULE);
 273         return PTR_ERR_OR_ZERO(isl12022->rtc);
 274 }
 275
 276 #ifdef CONFIG_OF
 277 static const struct of_device_id isl12022_dt_match[] = {
 278         { .compatible = "isl,isl12022" },
 279         { },
 280 };
 281 #endif
 282
 283 static const struct i2c_device_id isl12022_id[] = {
 284         { "isl12022", 0 },
 285         { }
 286 };
 287 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 288
 289 static struct i2c_driver isl12022_driver = {
 290         .driver         = {
 291                 .name   = "rtc-isl12022",
 292 #ifdef CONFIG_OF
 293                 .of_match_table = of_match_ptr(isl12022_dt_match),
 294 #endif
 295         },
 296         .probe          = isl12022_probe,
 297         .id_table       = isl12022_id,
 298 };
 299
 300 module_i2c_driver(isl12022_driver);
 301
 302 MODULE_AUTHOR("roman.fietze@telemotive.de");
 303 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 304 MODULE_LICENSE("GPL");
 305 MODULE_VERSION(DRV_VERSION);