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
  20 #define DRV_VERSION "0.1"
  21
  22 /* ISL register offsets */
  23 #define ISL12022_REG_SC         0x00
  24 #define ISL12022_REG_MN         0x01
  25 #define ISL12022_REG_HR         0x02
  26 #define ISL12022_REG_DT         0x03
  27 #define ISL12022_REG_MO         0x04
  28 #define ISL12022_REG_YR         0x05
  29 #define ISL12022_REG_DW         0x06
  30
  31 #define ISL12022_REG_SR         0x07
  32 #define ISL12022_REG_INT        0x08
  33
  34 /* ISL register bits */
  35 #define ISL12022_HR_MIL         (1 << 7)        /* military or 24 hour time */
  36
  37 #define ISL12022_SR_LBAT85      (1 << 2)
  38 #define ISL12022_SR_LBAT75      (1 << 1)
  39
  40 #define ISL12022_INT_WRTC       (1 << 6)
  41
  42
  43 static struct i2c_driver isl12022_driver;
  44
  45 struct isl12022 {
  46         struct rtc_device *rtc;
  47
  48         bool write_enabled;     /* true if write enable is set */
  49 };
  50
  51
  52 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
  53                               uint8_t *data, size_t n)
  54 {
  55         struct i2c_msg msgs[] = {
  56                 {
  57                         .addr   = client->addr,
  58                         .flags  = 0,
  59                         .len    = 1,
  60                         .buf    = data
  61                 },              /* setup read ptr */
  62                 {
  63                         .addr   = client->addr,
  64                         .flags  = I2C_M_RD,
  65                         .len    = n,
  66                         .buf    = data
  67                 }
  68         };
  69
  70         int ret;
  71
  72         data[0] = reg;
  73         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  74         if (ret != ARRAY_SIZE(msgs)) {
  75                 dev_err(&client->dev, "%s: read error, ret=%d\n",
  76                         __func__, ret);
  77                 return -EIO;
  78         }
  79
  80         return 0;
  81 }
  82
  83
  84 static int isl12022_write_reg(struct i2c_client *client,
  85                               uint8_t reg, uint8_t val)
  86 {
  87         uint8_t data[2] = { reg, val };
  88         int err;
  89
  90         err = i2c_master_send(client, data, sizeof(data));
  91         if (err != sizeof(data)) {
  92                 dev_err(&client->dev,
  93                         "%s: err=%d addr=%02x, data=%02x\n",
  94                         __func__, err, data[0], data[1]);
  95                 return -EIO;
  96         }
  97
  98         return 0;
  99 }
 100
 101
 102 /*
 103  * In the routines that deal directly with the isl12022 hardware, we use
 104  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 105  */
 106 static int isl12022_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 107 {
 108         uint8_t buf[ISL12022_REG_INT + 1];
 109         int ret;
 110
 111         ret = isl12022_read_regs(client, ISL12022_REG_SC, buf, sizeof(buf));
 112         if (ret)
 113                 return ret;
 114
 115         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
 116                 dev_warn(&client->dev,
 117                          "voltage dropped below %u%%, "
 118                          "date and time is not reliable.\n",
 119                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
 120         }
 121
 122         dev_dbg(&client->dev,
 123                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 124                 "mday=%02x, mon=%02x, year=%02x, wday=%02x, "
 125                 "sr=%02x, int=%02x",
 126                 __func__,
 127                 buf[ISL12022_REG_SC],
 128                 buf[ISL12022_REG_MN],
 129                 buf[ISL12022_REG_HR],
 130                 buf[ISL12022_REG_DT],
 131                 buf[ISL12022_REG_MO],
 132                 buf[ISL12022_REG_YR],
 133                 buf[ISL12022_REG_DW],
 134                 buf[ISL12022_REG_SR],
 135                 buf[ISL12022_REG_INT]);
 136
 137         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 138         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 139         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 140         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 141         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 142         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 143         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
 144
 145         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 146                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 147                 __func__,
 148                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 149                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 150
 151         /* The clock can give out invalid datetime, but we cannot return
 152          * -EINVAL otherwise hwclock will refuse to set the time on bootup. */
 153         if (rtc_valid_tm(tm) < 0)
 154                 dev_err(&client->dev, "retrieved date and time is invalid.\n");
 155
 156         return 0;
 157 }
 158
 159 static int isl12022_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 160 {
 161         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 162         size_t i;
 163         int ret;
 164         uint8_t buf[ISL12022_REG_DW + 1];
 165
 166         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 167                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 168                 __func__,
 169                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 170                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 171
 172         if (!isl12022->write_enabled) {
 173
 174                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 175                 if (ret)
 176                         return ret;
 177
 178                 /* Check if WRTC (write rtc enable) is set factory default is
 179                  * 0 (not set) */
 180                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 181                         dev_info(&client->dev,
 182                                  "init write enable and 24 hour format\n");
 183
 184                         /* Set the write enable bit. */
 185                         ret = isl12022_write_reg(client,
 186                                                  ISL12022_REG_INT,
 187                                                  buf[0] | ISL12022_INT_WRTC);
 188                         if (ret)
 189                                 return ret;
 190
 191                         /* Write to any RTC register to start RTC, we use the
 192                          * HR register, setting the MIL bit to use the 24 hour
 193                          * format. */
 194                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 195                                                  buf, 1);
 196                         if (ret)
 197                                 return ret;
 198
 199                         ret = isl12022_write_reg(client,
 200                                                  ISL12022_REG_HR,
 201                                                  buf[0] | ISL12022_HR_MIL);
 202                         if (ret)
 203                                 return ret;
 204                 }
 205
 206                 isl12022->write_enabled = 1;
 207         }
 208
 209         /* hours, minutes and seconds */
 210         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 211         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 212         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 213
 214         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 215
 216         /* month, 1 - 12 */
 217         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 218
 219         /* year and century */
 220         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 221
 222         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 223
 224         /* write register's data */
 225         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 226                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 227                                          buf[ISL12022_REG_SC + i]);
 228                 if (ret)
 229                         return -EIO;
 230         }
 231
 232         return 0;
 233 }
 234
 235 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 236 {
 237         return isl12022_get_datetime(to_i2c_client(dev), tm);
 238 }
 239
 240 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 241 {
 242         return isl12022_set_datetime(to_i2c_client(dev), tm);
 243 }
 244
 245 static const struct rtc_class_ops isl12022_rtc_ops = {
 246         .read_time      = isl12022_rtc_read_time,
 247         .set_time       = isl12022_rtc_set_time,
 248 };
 249
 250 static int isl12022_probe(struct i2c_client *client,
 251                           const struct i2c_device_id *id)
 252 {
 253         struct isl12022 *isl12022;
 254
 255         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 256                 return -ENODEV;
 257
 258         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
 259                                 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 = devm_rtc_device_register(&client->dev,
 268                                         isl12022_driver.driver.name,
 269                                         &isl12022_rtc_ops, THIS_MODULE);
 270         if (IS_ERR(isl12022->rtc))
 271                 return PTR_ERR(isl12022->rtc);
 272
 273         return 0;
 274 }
 275
 276 static int isl12022_remove(struct i2c_client *client)
 277 {
 278         return 0;
 279 }
 280
 281 static const struct i2c_device_id isl12022_id[] = {
 282         { "isl12022", 0 },
 283         { }
 284 };
 285 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 286
 287 static struct i2c_driver isl12022_driver = {
 288         .driver         = {
 289                 .name   = "rtc-isl12022",
 290         },
 291         .probe          = isl12022_probe,
 292         .remove         = isl12022_remove,
 293         .id_table       = isl12022_id,
 294 };
 295
 296 module_i2c_driver(isl12022_driver);
 297
 298 MODULE_AUTHOR("roman.fietze@telemotive.de");
 299 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 300 MODULE_LICENSE("GPL");
 301 MODULE_VERSION(DRV_VERSION);