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/rtc.h>
  30 #include <linux/of.h>
  31 #include <linux/of_device.h>
  32 #include <linux/regmap.h>
  33
  34 #define DRV_NAME "rtc-isl12057"
  35
  36 /* RTC section */
  37 #define ISL12057_REG_RTC_SC     0x00    /* Seconds */
  38 #define ISL12057_REG_RTC_MN     0x01    /* Minutes */
  39 #define ISL12057_REG_RTC_HR     0x02    /* Hours */
  40 #define ISL12057_REG_RTC_HR_PM  BIT(5)  /* AM/PM bit in 12h format */
  41 #define ISL12057_REG_RTC_HR_MIL BIT(6)  /* 24h/12h format */
  42 #define ISL12057_REG_RTC_DW     0x03    /* Day of the Week */
  43 #define ISL12057_REG_RTC_DT     0x04    /* Date */
  44 #define ISL12057_REG_RTC_MO     0x05    /* Month */
  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
 105 static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
 106 {
 107         /*
 108          * The clock has an 8 bit wide bcd-coded register for the year.
 109          * tm_year is an offset from 1900 and we are interested in the
 110          * 2000-2099 range, so any value less than 100 is invalid.
 111          */
 112         if (tm->tm_year < 100)
 113                 return -EINVAL;
 114
 115         regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
 116         regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
 117         regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
 118         regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
 119         regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
 120         regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
 121         regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
 122
 123         return 0;
 124 }
 125
 126 /*
 127  * Try and match register bits w/ fixed null values to see whether we
 128  * are dealing with an ISL12057. Note: this function is called early
 129  * during init and hence does need mutex protection.
 130  */
 131 static int isl12057_i2c_validate_chip(struct regmap *regmap)
 132 {
 133         u8 regs[ISL12057_MEM_MAP_LEN];
 134         static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
 135                                                        0xc0, 0x60, 0x00, 0x00,
 136                                                        0x00, 0x00, 0x00, 0x00,
 137                                                        0x00, 0x00, 0x60, 0x7c };
 138         int ret, i;
 139
 140         ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
 141         if (ret)
 142                 return ret;
 143
 144         for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
 145                 if (regs[i] & mask[i])  /* check if bits are cleared */
 146                         return -ENODEV;
 147         }
 148
 149         return 0;
 150 }
 151
 152 static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
 153 {
 154         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 155         u8 regs[ISL12057_RTC_SEC_LEN];
 156         int ret;
 157
 158         mutex_lock(&data->lock);
 159         ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
 160                                ISL12057_RTC_SEC_LEN);
 161         mutex_unlock(&data->lock);
 162
 163         if (ret) {
 164                 dev_err(dev, "%s: RTC read failed\n", __func__);
 165                 return ret;
 166         }
 167
 168         isl12057_rtc_regs_to_tm(tm, regs);
 169
 170         return rtc_valid_tm(tm);
 171 }
 172
 173 static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
 174 {
 175         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 176         u8 regs[ISL12057_RTC_SEC_LEN];
 177         int ret;
 178
 179         ret = isl12057_rtc_tm_to_regs(regs, tm);
 180         if (ret)
 181                 return ret;
 182
 183         mutex_lock(&data->lock);
 184         ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
 185                                 ISL12057_RTC_SEC_LEN);
 186         mutex_unlock(&data->lock);
 187
 188         if (ret)
 189                 dev_err(dev, "%s: RTC write failed\n", __func__);
 190
 191         return ret;
 192 }
 193
 194 /*
 195  * Check current RTC status and enable/disable what needs to be. Return 0 if
 196  * everything went ok and a negative value upon error. Note: this function
 197  * is called early during init and hence does need mutex protection.
 198  */
 199 static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
 200 {
 201         int ret;
 202
 203         /* Enable oscillator if not already running */
 204         ret = regmap_update_bits(regmap, ISL12057_REG_INT,
 205                                  ISL12057_REG_INT_EOSC, 0);
 206         if (ret < 0) {
 207                 dev_err(dev, "Unable to enable oscillator\n");
 208                 return ret;
 209         }
 210
 211         /* Clear oscillator failure bit if needed */
 212         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
 213                                  ISL12057_REG_SR_OSF, 0);
 214         if (ret < 0) {
 215                 dev_err(dev, "Unable to clear oscillator failure bit\n");
 216                 return ret;
 217         }
 218
 219         /* Clear alarm bit if needed */
 220         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
 221                                  ISL12057_REG_SR_A1F, 0);
 222         if (ret < 0) {
 223                 dev_err(dev, "Unable to clear alarm bit\n");
 224                 return ret;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static const struct rtc_class_ops rtc_ops = {
 231         .read_time = isl12057_rtc_read_time,
 232         .set_time = isl12057_rtc_set_time,
 233 };
 234
 235 static struct regmap_config isl12057_rtc_regmap_config = {
 236         .reg_bits = 8,
 237         .val_bits = 8,
 238 };
 239
 240 static int isl12057_probe(struct i2c_client *client,
 241                           const struct i2c_device_id *id)
 242 {
 243         struct device *dev = &client->dev;
 244         struct isl12057_rtc_data *data;
 245         struct rtc_device *rtc;
 246         struct regmap *regmap;
 247         int ret;
 248
 249         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 250                                      I2C_FUNC_SMBUS_BYTE_DATA |
 251                                      I2C_FUNC_SMBUS_I2C_BLOCK))
 252                 return -ENODEV;
 253
 254         regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
 255         if (IS_ERR(regmap)) {
 256                 ret = PTR_ERR(regmap);
 257                 dev_err(dev, "regmap allocation failed: %d\n", ret);
 258                 return ret;
 259         }
 260
 261         ret = isl12057_i2c_validate_chip(regmap);
 262         if (ret)
 263                 return ret;
 264
 265         ret = isl12057_check_rtc_status(dev, regmap);
 266         if (ret)
 267                 return ret;
 268
 269         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 270         if (!data)
 271                 return -ENOMEM;
 272
 273         mutex_init(&data->lock);
 274         data->regmap = regmap;
 275         dev_set_drvdata(dev, data);
 276
 277         rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
 278         if (IS_ERR(rtc))
 279                 return PTR_ERR(rtc);
 280
 281         return 0;
 282 }
 283
 284 #ifdef CONFIG_OF
 285 static struct of_device_id isl12057_dt_match[] = {
 286         { .compatible = "isl,isl12057" },
 287         { },
 288 };
 289 #endif
 290
 291 static const struct i2c_device_id isl12057_id[] = {
 292         { "isl12057", 0 },
 293         { }
 294 };
 295 MODULE_DEVICE_TABLE(i2c, isl12057_id);
 296
 297 static struct i2c_driver isl12057_driver = {
 298         .driver = {
 299                 .name = DRV_NAME,
 300                 .owner = THIS_MODULE,
 301                 .of_match_table = of_match_ptr(isl12057_dt_match),
 302         },
 303         .probe    = isl12057_probe,
 304         .id_table = isl12057_id,
 305 };
 306 module_i2c_driver(isl12057_driver);
 307
 308 MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
 309 MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
 310 MODULE_LICENSE("GPL");