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/bcd.h>
  12 #include <linux/err.h>
  13 #include <linux/hwmon.h>
  14 #include <linux/i2c.h>
  15 #include <linux/module.h>
  16 #include <linux/regmap.h>
  17 #include <linux/rtc.h>
  18 #include <linux/slab.h>
  19
  20 #include <asm/byteorder.h>
  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 #define ISL12022_REG_BETA       0x0d
  35 #define ISL12022_REG_TEMP_L     0x28
  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 #define ISL12022_BETA_TSE       (1 << 7)
  46
  47 static umode_t isl12022_hwmon_is_visible(const void *data,
  48                                          enum hwmon_sensor_types type,
  49                                          u32 attr, int channel)
  50 {
  51         if (type == hwmon_temp && attr == hwmon_temp_input)
  52                 return 0444;
  53
  54         return 0;
  55 }
  56
  57 /*
  58  * A user-initiated temperature conversion is not started by this function,
  59  * so the temperature is updated once every ~60 seconds.
  60  */
  61 static int isl12022_hwmon_read_temp(struct device *dev, long *mC)
  62 {
  63         struct regmap *regmap = dev_get_drvdata(dev);
  64         int temp, ret;
  65         __le16 buf;
  66
  67         ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L, &buf, sizeof(buf));
  68         if (ret)
  69                 return ret;
  70         /*
  71          * Temperature is represented as a 10-bit number, unit half-Kelvins.
  72          */
  73         temp = le16_to_cpu(buf);
  74         temp *= 500;
  75         temp -= 273000;
  76
  77         *mC = temp;
  78
  79         return 0;
  80 }
  81
  82 static int isl12022_hwmon_read(struct device *dev,
  83                                enum hwmon_sensor_types type,
  84                                u32 attr, int channel, long *val)
  85 {
  86         if (type == hwmon_temp && attr == hwmon_temp_input)
  87                 return isl12022_hwmon_read_temp(dev, val);
  88
  89         return -EOPNOTSUPP;
  90 }
  91
  92 static const struct hwmon_channel_info *isl12022_hwmon_info[] = {
  93         HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
  94         NULL
  95 };
  96
  97 static const struct hwmon_ops isl12022_hwmon_ops = {
  98         .is_visible = isl12022_hwmon_is_visible,
  99         .read = isl12022_hwmon_read,
 100 };
 101
 102 static const struct hwmon_chip_info isl12022_hwmon_chip_info = {
 103         .ops = &isl12022_hwmon_ops,
 104         .info = isl12022_hwmon_info,
 105 };
 106
 107 static void isl12022_hwmon_register(struct device *dev)
 108 {
 109         struct regmap *regmap = dev_get_drvdata(dev);
 110         struct device *hwmon;
 111         int ret;
 112
 113         if (!IS_REACHABLE(CONFIG_HWMON))
 114                 return;
 115
 116         ret = regmap_update_bits(regmap, ISL12022_REG_BETA,
 117                                  ISL12022_BETA_TSE, ISL12022_BETA_TSE);
 118         if (ret) {
 119                 dev_warn(dev, "unable to enable temperature sensor\n");
 120                 return;
 121         }
 122
 123         hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", regmap,
 124                                                      &isl12022_hwmon_chip_info,
 125                                                      NULL);
 126         if (IS_ERR(hwmon))
 127                 dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);
 128 }
 129
 130 /*
 131  * In the routines that deal directly with the isl12022 hardware, we use
 132  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 133  */
 134 static int isl12022_rtc_read_time(struct device *dev, struct rtc_time *tm)
 135 {
 136         struct regmap *regmap = dev_get_drvdata(dev);
 137         uint8_t buf[ISL12022_REG_INT + 1];
 138         int ret;
 139
 140         ret = regmap_bulk_read(regmap, ISL12022_REG_SC, buf, sizeof(buf));
 141         if (ret)
 142                 return ret;
 143
 144         if (buf[ISL12022_REG_SR] & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
 145                 dev_warn(dev,
 146                          "voltage dropped below %u%%, date and time is not reliable.\n",
 147                          buf[ISL12022_REG_SR] & ISL12022_SR_LBAT85 ? 85 : 75);
 148         }
 149
 150         dev_dbg(dev,
 151                 "raw data is sec=%02x, min=%02x, hr=%02x, mday=%02x, mon=%02x, year=%02x, wday=%02x, sr=%02x, int=%02x",
 152                 buf[ISL12022_REG_SC],
 153                 buf[ISL12022_REG_MN],
 154                 buf[ISL12022_REG_HR],
 155                 buf[ISL12022_REG_DT],
 156                 buf[ISL12022_REG_MO],
 157                 buf[ISL12022_REG_YR],
 158                 buf[ISL12022_REG_DW],
 159                 buf[ISL12022_REG_SR],
 160                 buf[ISL12022_REG_INT]);
 161
 162         tm->tm_sec = bcd2bin(buf[ISL12022_REG_SC] & 0x7F);
 163         tm->tm_min = bcd2bin(buf[ISL12022_REG_MN] & 0x7F);
 164         tm->tm_hour = bcd2bin(buf[ISL12022_REG_HR] & 0x3F);
 165         tm->tm_mday = bcd2bin(buf[ISL12022_REG_DT] & 0x3F);
 166         tm->tm_wday = buf[ISL12022_REG_DW] & 0x07;
 167         tm->tm_mon = bcd2bin(buf[ISL12022_REG_MO] & 0x1F) - 1;
 168         tm->tm_year = bcd2bin(buf[ISL12022_REG_YR]) + 100;
 169
 170         dev_dbg(dev, "%s: %ptR\n", __func__, tm);
 171
 172         return 0;
 173 }
 174
 175 static int isl12022_rtc_set_time(struct device *dev, struct rtc_time *tm)
 176 {
 177         struct regmap *regmap = dev_get_drvdata(dev);
 178         int ret;
 179         uint8_t buf[ISL12022_REG_DW + 1];
 180
 181         dev_dbg(dev, "%s: %ptR\n", __func__, tm);
 182
 183         /* Ensure the write enable bit is set. */
 184         ret = regmap_update_bits(regmap, ISL12022_REG_INT,
 185                                  ISL12022_INT_WRTC, ISL12022_INT_WRTC);
 186         if (ret)
 187                 return ret;
 188
 189         /* hours, minutes and seconds */
 190         buf[ISL12022_REG_SC] = bin2bcd(tm->tm_sec);
 191         buf[ISL12022_REG_MN] = bin2bcd(tm->tm_min);
 192         buf[ISL12022_REG_HR] = bin2bcd(tm->tm_hour) | ISL12022_HR_MIL;
 193
 194         buf[ISL12022_REG_DT] = bin2bcd(tm->tm_mday);
 195
 196         /* month, 1 - 12 */
 197         buf[ISL12022_REG_MO] = bin2bcd(tm->tm_mon + 1);
 198
 199         /* year and century */
 200         buf[ISL12022_REG_YR] = bin2bcd(tm->tm_year % 100);
 201
 202         buf[ISL12022_REG_DW] = tm->tm_wday & 0x07;
 203
 204         return regmap_bulk_write(regmap, ISL12022_REG_SC, buf, sizeof(buf));
 205 }
 206
 207 static const struct rtc_class_ops isl12022_rtc_ops = {
 208         .read_time      = isl12022_rtc_read_time,
 209         .set_time       = isl12022_rtc_set_time,
 210 };
 211
 212 static const struct regmap_config regmap_config = {
 213         .reg_bits = 8,
 214         .val_bits = 8,
 215         .use_single_write = true,
 216 };
 217
 218 static int isl12022_probe(struct i2c_client *client)
 219 {
 220         struct rtc_device *rtc;
 221         struct regmap *regmap;
 222
 223         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 224                 return -ENODEV;
 225
 226         regmap = devm_regmap_init_i2c(client, &regmap_config);
 227         if (IS_ERR(regmap)) {
 228                 dev_err(&client->dev, "regmap allocation failed\n");
 229                 return PTR_ERR(regmap);
 230         }
 231
 232         dev_set_drvdata(&client->dev, regmap);
 233
 234         isl12022_hwmon_register(&client->dev);
 235
 236         rtc = devm_rtc_allocate_device(&client->dev);
 237         if (IS_ERR(rtc))
 238                 return PTR_ERR(rtc);
 239
 240         rtc->ops = &isl12022_rtc_ops;
 241         rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 242         rtc->range_max = RTC_TIMESTAMP_END_2099;
 243
 244         return devm_rtc_register_device(rtc);
 245 }
 246
 247 static const struct of_device_id isl12022_dt_match[] = {
 248         { .compatible = "isl,isl12022" }, /* for backward compat., don't use */
 249         { .compatible = "isil,isl12022" },
 250         { },
 251 };
 252 MODULE_DEVICE_TABLE(of, isl12022_dt_match);
 253
 254 static const struct i2c_device_id isl12022_id[] = {
 255         { "isl12022", 0 },
 256         { }
 257 };
 258 MODULE_DEVICE_TABLE(i2c, isl12022_id);
 259
 260 static struct i2c_driver isl12022_driver = {
 261         .driver         = {
 262                 .name   = "rtc-isl12022",
 263                 .of_match_table = isl12022_dt_match,
 264         },
 265         .probe_new      = isl12022_probe,
 266         .id_table       = isl12022_id,
 267 };
 268
 269 module_i2c_driver(isl12022_driver);
 270
 271 MODULE_AUTHOR("roman.fietze@telemotive.de");
 272 MODULE_DESCRIPTION("ISL 12022 RTC driver");
 273 MODULE_LICENSE("GPL");