drivers/rtc/rtc-isl12057.c

   1 /*
   2  * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
   3  *
   4  * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
   5  *
   6  * This work is largely based on Intersil ISL1208 driver developed by
   7  * Hebert Valerio Riedel <hvr@gnu.org>.
   8  *
   9  * Detailed datasheet on which this development is based is available here:
  10  *
  11  *  http://natisbad.org/NAS2/refs/ISL12057.pdf
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/mutex.h>
  26 #include <linux/rtc.h>
  27 #include <linux/i2c.h>
  28 #include <linux/bcd.h>
  29 #include <linux/of.h>
  30 #include <linux/of_device.h>
  31 #include <linux/regmap.h>
  32
  33 #define DRV_NAME "rtc-isl12057"
  34
  35 /* RTC section */
  36 #define ISL12057_REG_RTC_SC     0x00    /* Seconds */
  37 #define ISL12057_REG_RTC_MN     0x01    /* Minutes */
  38 #define ISL12057_REG_RTC_HR     0x02    /* Hours */
  39 #define ISL12057_REG_RTC_HR_PM  BIT(5)  /* AM/PM bit in 12h format */
  40 #define ISL12057_REG_RTC_HR_MIL BIT(6)  /* 24h/12h format */
  41 #define ISL12057_REG_RTC_DW     0x03    /* Day of the Week */
  42 #define ISL12057_REG_RTC_DT     0x04    /* Date */
  43 #define ISL12057_REG_RTC_MO     0x05    /* Month */
  44 #define ISL12057_REG_RTC_MO_CEN BIT(7)  /* Century bit */
  45 #define ISL12057_REG_RTC_YR     0x06    /* Year */
  46 #define ISL12057_RTC_SEC_LEN    7
  47
  48 /* Alarm 1 section */
  49 #define ISL12057_REG_A1_SC      0x07    /* Alarm 1 Seconds */
  50 #define ISL12057_REG_A1_MN      0x08    /* Alarm 1 Minutes */
  51 #define ISL12057_REG_A1_HR      0x09    /* Alarm 1 Hours */
  52 #define ISL12057_REG_A1_HR_PM   BIT(5)  /* AM/PM bit in 12h format */
  53 #define ISL12057_REG_A1_HR_MIL  BIT(6)  /* 24h/12h format */
  54 #define ISL12057_REG_A1_DWDT    0x0A    /* Alarm 1 Date / Day of the week */
  55 #define ISL12057_REG_A1_DWDT_B  BIT(6)  /* DW / DT selection bit */
  56 #define ISL12057_A1_SEC_LEN     4
  57
  58 /* Alarm 2 section */
  59 #define ISL12057_REG_A2_MN      0x0B    /* Alarm 2 Minutes */
  60 #define ISL12057_REG_A2_HR      0x0C    /* Alarm 2 Hours */
  61 #define ISL12057_REG_A2_DWDT    0x0D    /* Alarm 2 Date / Day of the week */
  62 #define ISL12057_A2_SEC_LEN     3
  63
  64 /* Control/Status registers */
  65 #define ISL12057_REG_INT        0x0E
  66 #define ISL12057_REG_INT_A1IE   BIT(0)  /* Alarm 1 interrupt enable bit */
  67 #define ISL12057_REG_INT_A2IE   BIT(1)  /* Alarm 2 interrupt enable bit */
  68 #define ISL12057_REG_INT_INTCN  BIT(2)  /* Interrupt control enable bit */
  69 #define ISL12057_REG_INT_RS1    BIT(3)  /* Freq out control bit 1 */
  70 #define ISL12057_REG_INT_RS2    BIT(4)  /* Freq out control bit 2 */
  71 #define ISL12057_REG_INT_EOSC   BIT(7)  /* Oscillator enable bit */
  72
  73 #define ISL12057_REG_SR         0x0F
  74 #define ISL12057_REG_SR_A1F     BIT(0)  /* Alarm 1 interrupt bit */
  75 #define ISL12057_REG_SR_A2F     BIT(1)  /* Alarm 2 interrupt bit */
  76 #define ISL12057_REG_SR_OSF     BIT(7)  /* Oscillator failure bit */
  77
  78 /* Register memory map length */
  79 #define ISL12057_MEM_MAP_LEN    0x10
  80
  81 struct isl12057_rtc_data {
  82         struct regmap *regmap;
  83         struct mutex lock;
  84 };
  85
  86 static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
  87 {
  88         tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
  89         tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
  90
  91         if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
  92                 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x1f);
  93                 if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
  94                         tm->tm_hour += 12;
  95         } else {                                            /* 24 hour mode */
  96                 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
  97         }
  98
  99         tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
 100         tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
 101         tm->tm_mon  = bcd2bin(regs[ISL12057_REG_RTC_MO] & 0x1f) - 1; /* ditto */
 102         tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
 103
 104         /* Check if years register has overflown from 99 to 00 */
 105         if (regs[ISL12057_REG_RTC_MO] & ISL12057_REG_RTC_MO_CEN)
 106                 tm->tm_year += 100;
 107 }
 108
 109 static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
 110 {
 111         u8 century_bit;
 112
 113         /*
 114          * The clock has an 8 bit wide bcd-coded register for the year.
 115          * It also has a century bit encoded in MO flag which provides
 116          * information about overflow of year register from 99 to 00.
 117          * tm_year is an offset from 1900 and we are interested in the
 118          * 2000-2199 range, so any value less than 100 or larger than
 119          * 299 is invalid.
 120          */
 121         if (tm->tm_year < 100 || tm->tm_year > 299)
 122                 return -EINVAL;
 123
 124         century_bit = (tm->tm_year > 199) ? ISL12057_REG_RTC_MO_CEN : 0;
 125
 126         regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
 127         regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
 128         regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
 129         regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
 130         regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1) | century_bit;
 131         regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year % 100);
 132         regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
 133
 134         return 0;
 135 }
 136
 137 /*
 138  * Try and match register bits w/ fixed null values to see whether we
 139  * are dealing with an ISL12057. Note: this function is called early
 140  * during init and hence does need mutex protection.
 141  */
 142 static int isl12057_i2c_validate_chip(struct regmap *regmap)
 143 {
 144         u8 regs[ISL12057_MEM_MAP_LEN];
 145         static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
 146                                                        0xc0, 0x60, 0x00, 0x00,
 147                                                        0x00, 0x00, 0x00, 0x00,
 148                                                        0x00, 0x00, 0x60, 0x7c };
 149         int ret, i;
 150
 151         ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
 152         if (ret)
 153                 return ret;
 154
 155         for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
 156                 if (regs[i] & mask[i])  /* check if bits are cleared */
 157                         return -ENODEV;
 158         }
 159
 160         return 0;
 161 }
 162
 163 static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
 164 {
 165         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 166         u8 regs[ISL12057_RTC_SEC_LEN];
 167         unsigned int sr;
 168         int ret;
 169
 170         mutex_lock(&data->lock);
 171         ret = regmap_read(data->regmap, ISL12057_REG_SR, &sr);
 172         if (ret) {
 173                 dev_err(dev, "%s: unable to read oscillator status flag (%d)\n",
 174                         __func__, ret);
 175                 goto out;
 176         } else {
 177                 if (sr & ISL12057_REG_SR_OSF) {
 178                         ret = -ENODATA;
 179                         goto out;
 180                 }
 181         }
 182
 183         ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
 184                                ISL12057_RTC_SEC_LEN);
 185         if (ret)
 186                 dev_err(dev, "%s: unable to read RTC time section (%d)\n",
 187                         __func__, ret);
 188
 189 out:
 190         mutex_unlock(&data->lock);
 191
 192         if (ret)
 193                 return ret;
 194
 195         isl12057_rtc_regs_to_tm(tm, regs);
 196
 197         return rtc_valid_tm(tm);
 198 }
 199
 200 static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
 201 {
 202         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 203         u8 regs[ISL12057_RTC_SEC_LEN];
 204         int ret;
 205
 206         ret = isl12057_rtc_tm_to_regs(regs, tm);
 207         if (ret)
 208                 return ret;
 209
 210         mutex_lock(&data->lock);
 211         ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
 212                                 ISL12057_RTC_SEC_LEN);
 213         if (ret) {
 214                 dev_err(dev, "%s: unable to write RTC time section (%d)\n",
 215                         __func__, ret);
 216                 goto out;
 217         }
 218
 219         /*
 220          * Now that RTC time has been updated, let's clear oscillator
 221          * failure flag, if needed.
 222          */
 223         ret = regmap_update_bits(data->regmap, ISL12057_REG_SR,
 224                                  ISL12057_REG_SR_OSF, 0);
 225         if (ret < 0)
 226                 dev_err(dev, "%s: unable to clear osc. failure bit (%d)\n",
 227                         __func__, ret);
 228
 229 out:
 230         mutex_unlock(&data->lock);
 231
 232         return ret;
 233 }
 234
 235 /*
 236  * Check current RTC status and enable/disable what needs to be. Return 0 if
 237  * everything went ok and a negative value upon error. Note: this function
 238  * is called early during init and hence does need mutex protection.
 239  */
 240 static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
 241 {
 242         int ret;
 243
 244         /* Enable oscillator if not already running */
 245         ret = regmap_update_bits(regmap, ISL12057_REG_INT,
 246                                  ISL12057_REG_INT_EOSC, 0);
 247         if (ret < 0) {
 248                 dev_err(dev, "%s: unable to enable oscillator (%d)\n",
 249                         __func__, ret);
 250                 return ret;
 251         }
 252
 253         /* Clear alarm bit if needed */
 254         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
 255                                  ISL12057_REG_SR_A1F, 0);
 256         if (ret < 0) {
 257                 dev_err(dev, "%s: unable to clear alarm bit (%d)\n",
 258                         __func__, ret);
 259                 return ret;
 260         }
 261
 262         return 0;
 263 }
 264
 265 static const struct rtc_class_ops rtc_ops = {
 266         .read_time = isl12057_rtc_read_time,
 267         .set_time = isl12057_rtc_set_time,
 268 };
 269
 270 static struct regmap_config isl12057_rtc_regmap_config = {
 271         .reg_bits = 8,
 272         .val_bits = 8,
 273 };
 274
 275 static int isl12057_probe(struct i2c_client *client,
 276                           const struct i2c_device_id *id)
 277 {
 278         struct device *dev = &client->dev;
 279         struct isl12057_rtc_data *data;
 280         struct rtc_device *rtc;
 281         struct regmap *regmap;
 282         int ret;
 283
 284         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 285                                      I2C_FUNC_SMBUS_BYTE_DATA |
 286                                      I2C_FUNC_SMBUS_I2C_BLOCK))
 287                 return -ENODEV;
 288
 289         regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
 290         if (IS_ERR(regmap)) {
 291                 ret = PTR_ERR(regmap);
 292                 dev_err(dev, "%s: regmap allocation failed (%d)\n",
 293                         __func__, ret);
 294                 return ret;
 295         }
 296
 297         ret = isl12057_i2c_validate_chip(regmap);
 298         if (ret)
 299                 return ret;
 300
 301         ret = isl12057_check_rtc_status(dev, regmap);
 302         if (ret)
 303                 return ret;
 304
 305         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 306         if (!data)
 307                 return -ENOMEM;
 308
 309         mutex_init(&data->lock);
 310         data->regmap = regmap;
 311         dev_set_drvdata(dev, data);
 312
 313         rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
 314         return PTR_ERR_OR_ZERO(rtc);
 315 }
 316
 317 #ifdef CONFIG_OF
 318 static const struct of_device_id isl12057_dt_match[] = {
 319         { .compatible = "isl,isl12057" },
 320         { },
 321 };
 322 #endif
 323
 324 static const struct i2c_device_id isl12057_id[] = {
 325         { "isl12057", 0 },
 326         { }
 327 };
 328 MODULE_DEVICE_TABLE(i2c, isl12057_id);
 329
 330 static struct i2c_driver isl12057_driver = {
 331         .driver = {
 332                 .name = DRV_NAME,
 333                 .owner = THIS_MODULE,
 334                 .of_match_table = of_match_ptr(isl12057_dt_match),
 335         },
 336         .probe    = isl12057_probe,
 337         .id_table = isl12057_id,
 338 };
 339 module_i2c_driver(isl12057_driver);
 340
 341 MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
 342 MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
 343 MODULE_LICENSE("GPL");