drivers/rtc/rtc-isl12022.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * An I2C driver for the Intersil ISL 12022
   4  *
   5  * Author: Roman Fietze <roman.fietze@telemotive.de>
   6  *
   7  * Based on the Philips PCF8563 RTC
   8  * by Alessandro Zummo <a.zummo@towertech.it>.
   9  */
  10
  11 #include <linux/i2c.h>
  12 #include <linux/bcd.h>
  13 #include <linux/rtc.h>
  14 #include <linux/slab.h>
  15 #include <linux/module.h>
  16 #include <linux/err.h>
  17 #include <linux/of.h>
  18 #include <linux/of_device.h>
  19
  20 /* ISL register offsets */
  21 #define ISL12022_REG_SC         0x00
  22 #define ISL12022_REG_MN         0x01
  23 #define ISL12022_REG_HR         0x02
  24 #define ISL12022_REG_DT         0x03
  25 #define ISL12022_REG_MO         0x04
  26 #define ISL12022_REG_YR         0x05
  27 #define ISL12022_REG_DW         0x06
  28
  29 #define ISL12022_REG_SR         0x07
  30 #define ISL12022_REG_INT        0x08
  31
  32 /* ISL register bits */
  33 #define ISL12022_HR_MIL         (1 << 7)        /* military or 24 hour time */
  34
  35 #define ISL12022_SR_LBAT85      (1 << 2)
  36 #define ISL12022_SR_LBAT75      (1 << 1)
  37
  38 #define ISL12022_INT_WRTC       (1 << 6)
  39
  40
  41 static struct i2c_driver isl12022_driver;
  42
  43 struct isl12022 {
  44         struct rtc_device *rtc;
  45
  46         bool write_enabled;     /* true if write enable is set */
  47 };
  48
  49
  50 static int isl12022_read_regs(struct i2c_client *client, uint8_t reg,
  51                               uint8_t *data, size_t n)
  52 {
  53         struct i2c_msg msgs[] = {
  54                 {
  55                         .addr   = client->addr,
  56                         .flags  = 0,
  57                         .len    = 1,
  58                         .buf    = data
  59                 },              /* setup read ptr */
  60                 {
  61                         .addr   = client->addr,
  62                         .flags  = I2C_M_RD,
  63                         .len    = n,
  64                         .buf    = data
  65                 }
  66         };
  67
  68         int ret;
  69
  70         data[0] = reg;
  71         ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  72         if (ret != ARRAY_SIZE(msgs)) {
  73                 dev_err(&client->dev, "%s: read error, ret=%d\n",
  74                         __func__, ret);
  75                 return -EIO;
  76         }
  77
  78         return 0;
  79 }
  80
  81
  82 static int isl12022_write_reg(struct i2c_client *client,
  83                               uint8_t reg, uint8_t val)
  84 {
  85         uint8_t data[2] = { reg, val };
  86         int err;
  87
  88         err = i2c_master_send(client, data, sizeof(data));
  89         if (err != sizeof(data)) {
  90                 dev_err(&client->dev,
  91                         "%s: err=%d addr=%02x, data=%02x\n",
  92                         __func__, err, data[0], data[1]);
  93                 return -EIO;
  94         }
  95
  96         return 0;
  97 }
  98
  99
 100 /*
 101  * In the routines that deal directly with the isl12022 hardware, we use
 102  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 103  */
 104 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 105 {
 106         struct i2c_client *client = to_i2c_client(dev);
 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         return 0;
 151 }
 152
 153 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 154 {
 155         struct i2c_client *client = to_i2c_client(dev);
 156         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 157         size_t i;
 158         int ret;
 159         uint8_t buf[ISL12022_REG_DW + 1];
 160
 161         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 162                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 163                 __func__,
 164                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 165                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 166
 167         if (!isl12022->write_enabled) {
 168
 169                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 170                 if (ret)
 171                         return ret;
 172
 173                 /* Check if WRTC (write rtc enable) is set factory default is
 174                  * 0 (not set) */
 175                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 176                         dev_info(&client->dev,
 177                                  "init write enable and 24 hour format\n");
 178
 179                         /* Set the write enable bit. */
 180                         ret = isl12022_write_reg(client,
 181                                                  ISL12022_REG_INT,
 182                                                  buf[0] | ISL12022_INT_WRTC);
 183                         if (ret)
 184                                 return ret;
 185
 186                         /* Write to any RTC register to start RTC, we use the
 187                          * HR register, setting the MIL bit to use the 24 hour
 188                          * format. */
 189                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 190                                                  buf, 1);
 191                         if (ret)
 192                                 return ret;
 193
 194                         ret = isl12022_write_reg(client,
 195                                                  ISL12022_REG_HR,
 196                                                  buf[0] | ISL12022_HR_MIL);
 197                         if (ret)
 198                                 return ret;
 199                 }
 200
 201                 isl12022->write_enabled = true;
 202         }
 203
 204         /* hours, minutes and seconds */
 205         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 206         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 207         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 208
 209         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 210
 211         /* month, 1 - 12 */
 212         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 213
 214         /* year and century */
 215         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 216
 217         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 218
 219         /* write register's data */
 220         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 221                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 222                                          buf[ISL12022_REG_SC + i]);
 223                 if (ret)
 224                         return -EIO;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static const struct rtc_class_ops isl12022_rtc_ops = {
 231         .read_time      = isl12022_rtc_read_time,
 232         .set_time       = isl12022_rtc_set_time,
 233 };
 234
 235 static int isl12022_probe(struct i2c_client *client,
 236                           const struct i2c_device_id *id)
 237 {
 238         struct isl12022 *isl12022;
 239
 240         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 241                 return -ENODEV;
 242
 243         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
 244                                 GFP_KERNEL);
 245         if (!isl12022)
 246                 return -ENOMEM;
 247
 248         i2c_set_clientdata(client, isl12022);
 249
 250         isl12022->rtc = devm_rtc_device_register(&client->dev,
 251                                         isl12022_driver.driver.name,
 252                                         &isl12022_rtc_ops, THIS_MODULE);
 253         return PTR_ERR_OR_ZERO(isl12022->rtc);
 254 }
 255
 256 #ifdef CONFIG_OF
 257 static const struct of_device_id isl12022_dt_match[] = {
 258         { .compatible = "isl,isl12022" }, /* for backward compat., don't use */
 259         { .compatible = "isil,isl12022" },
 260         { },
 261 };
 262 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
 263 #endif
 264
 265 static const struct i2c_device_id isl12022_id[] = {
 266         { "isl12022", 0 },
 267         { }
 268 };
 269 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 270
 271 static struct i2c_driver isl12022_driver = {
 272         .driver         = {
 273                 .name   = "rtc-isl12022",
 274 #ifdef CONFIG_OF
 275                 .of_match_table = of_match_ptr(isl12022_dt_match),
 276 #endif
 277         },
 278         .probe          = isl12022_probe,
 279         .id_table       = isl12022_id,
 280 };
 281
 282 module_i2c_driver(isl12022_driver);
 283
 284 MODULE_AUTHOR("roman.fietze@telemotive.de");
 285 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 286 MODULE_LICENSE("GPL");