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(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(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(dev, "%s: %ptR\n", __func__, tm);
 145
 146         return 0;
 147 }
 148
 149 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 150 {
 151         struct i2c_client *client = to_i2c_client(dev);
 152         struct isl12022 *isl12022 = i2c_get_clientdata(client);
 153         size_t i;
 154         int ret;
 155         uint8_t buf[ISL12022_REG_DW + 1];
 156
 157         dev_dbg(dev, "%s: %ptR\n", __func__, tm);
 158
 159         if (!isl12022->write_enabled) {
 160
 161                 ret = isl12022_read_regs(client, ISL12022_REG_INT, buf, 1);
 162                 if (ret)
 163                         return ret;
 164
 165                 /* Check if WRTC (write rtc enable) is set factory default is
 166                  * 0 (not set) */
 167                 if (!(buf[0] & ISL12022_INT_WRTC)) {
 168                         /* Set the write enable bit. */
 169                         ret = isl12022_write_reg(client,
 170                                                  ISL12022_REG_INT,
 171                                                  buf[0] | ISL12022_INT_WRTC);
 172                         if (ret)
 173                                 return ret;
 174
 175                         /* Write to any RTC register to start RTC, we use the
 176                          * HR register, setting the MIL bit to use the 24 hour
 177                          * format. */
 178                         ret = isl12022_read_regs(client, ISL12022_REG_HR,
 179                                                  buf, 1);
 180                         if (ret)
 181                                 return ret;
 182
 183                         ret = isl12022_write_reg(client,
 184                                                  ISL12022_REG_HR,
 185                                                  buf[0] | ISL12022_HR_MIL);
 186                         if (ret)
 187                                 return ret;
 188                 }
 189
 190                 isl12022->write_enabled = true;
 191         }
 192
 193         /* hours, minutes and seconds */
 194         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 195         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 196         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 197
 198         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 199
 200         /* month, 1 - 12 */
 201         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 202
 203         /* year and century */
 204         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 205
 206         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 207
 208         /* write register's data */
 209         for (i = 0; i < ARRAY_SIZE(buf); i++) {
 210                 ret = isl12022_write_reg(client, ISL12022_REG_SC + i,
 211                                          buf[ISL12022_REG_SC + i]);
 212                 if (ret)
 213                         return -EIO;
 214         }
 215
 216         return 0;
 217 }
 218
 219 static const struct rtc_class_ops isl12022_rtc_ops = {
 220         .read_time      = isl12022_rtc_read_time,
 221         .set_time       = isl12022_rtc_set_time,
 222 };
 223
 224 static int isl12022_probe(struct i2c_client *client)
 225 {
 226         struct isl12022 *isl12022;
 227
 228         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 229                 return -ENODEV;
 230
 231         isl12022 = devm_kzalloc(&client->dev, sizeof(struct isl12022),
 232                                 GFP_KERNEL);
 233         if (!isl12022)
 234                 return -ENOMEM;
 235
 236         i2c_set_clientdata(client, isl12022);
 237
 238         isl12022->rtc = devm_rtc_allocate_device(&client->dev);
 239         if (IS_ERR(isl12022->rtc))
 240                 return PTR_ERR(isl12022->rtc);
 241
 242         isl12022->rtc->ops = &isl12022_rtc_ops;
 243         isl12022->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 244         isl12022->rtc->range_max = RTC_TIMESTAMP_END_2099;
 245
 246         return devm_rtc_register_device(isl12022->rtc);
 247 }
 248
 249 #ifdef CONFIG_OF
 250 static const struct of_device_id isl12022_dt_match[] = {
 251         { .compatible = "isl,isl12022" }, /* for backward compat., don't use */
 252         { .compatible = "isil,isl12022" },
 253         { },
 254 };
 255 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
 256 #endif
 257
 258 static const struct i2c_device_id isl12022_id[] = {
 259         { "isl12022", 0 },
 260         { }
 261 };
 262 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 263
 264 static struct i2c_driver isl12022_driver = {
 265         .driver         = {
 266                 .name   = "rtc-isl12022",
 267 #ifdef CONFIG_OF
 268                 .of_match_table = of_match_ptr(isl12022_dt_match),
 269 #endif
 270         },
 271         .probe_new      = isl12022_probe,
 272         .id_table       = isl12022_id,
 273 };
 274
 275 module_i2c_driver(isl12022_driver);
 276
 277 MODULE_AUTHOR("roman.fietze@telemotive.de");
 278 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 279 MODULE_LICENSE("GPL");