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_YR     0x06    /* Year */
  45 #define ISL12057_RTC_SEC_LEN    7
  46
  47 /* Alarm 1 section */
  48 #define ISL12057_REG_A1_SC      0x07    /* Alarm 1 Seconds */
  49 #define ISL12057_REG_A1_MN      0x08    /* Alarm 1 Minutes */
  50 #define ISL12057_REG_A1_HR      0x09    /* Alarm 1 Hours */
  51 #define ISL12057_REG_A1_HR_PM   BIT(5)  /* AM/PM bit in 12h format */
  52 #define ISL12057_REG_A1_HR_MIL  BIT(6)  /* 24h/12h format */
  53 #define ISL12057_REG_A1_DWDT    0x0A    /* Alarm 1 Date / Day of the week */
  54 #define ISL12057_REG_A1_DWDT_B  BIT(6)  /* DW / DT selection bit */
  55 #define ISL12057_A1_SEC_LEN     4
  56
  57 /* Alarm 2 section */
  58 #define ISL12057_REG_A2_MN      0x0B    /* Alarm 2 Minutes */
  59 #define ISL12057_REG_A2_HR      0x0C    /* Alarm 2 Hours */
  60 #define ISL12057_REG_A2_DWDT    0x0D    /* Alarm 2 Date / Day of the week */
  61 #define ISL12057_A2_SEC_LEN     3
  62
  63 /* Control/Status registers */
  64 #define ISL12057_REG_INT        0x0E
  65 #define ISL12057_REG_INT_A1IE   BIT(0)  /* Alarm 1 interrupt enable bit */
  66 #define ISL12057_REG_INT_A2IE   BIT(1)  /* Alarm 2 interrupt enable bit */
  67 #define ISL12057_REG_INT_INTCN  BIT(2)  /* Interrupt control enable bit */
  68 #define ISL12057_REG_INT_RS1    BIT(3)  /* Freq out control bit 1 */
  69 #define ISL12057_REG_INT_RS2    BIT(4)  /* Freq out control bit 2 */
  70 #define ISL12057_REG_INT_EOSC   BIT(7)  /* Oscillator enable bit */
  71
  72 #define ISL12057_REG_SR         0x0F
  73 #define ISL12057_REG_SR_A1F     BIT(0)  /* Alarm 1 interrupt bit */
  74 #define ISL12057_REG_SR_A2F     BIT(1)  /* Alarm 2 interrupt bit */
  75 #define ISL12057_REG_SR_OSF     BIT(7)  /* Oscillator failure bit */
  76
  77 /* Register memory map length */
  78 #define ISL12057_MEM_MAP_LEN    0x10
  79
  80 struct isl12057_rtc_data {
  81         struct regmap *regmap;
  82         struct mutex lock;
  83 };
  84
  85 static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
  86 {
  87         tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
  88         tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
  89
  90         if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
  91                 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
  92                 if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
  93                         tm->tm_hour += 12;
  94         } else {                                            /* 24 hour mode */
  95                 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
  96         }
  97
  98         tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
  99         tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
 100         tm->tm_mon  = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
 101         tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
 102 }
 103
 104 static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
 105 {
 106         /*
 107          * The clock has an 8 bit wide bcd-coded register for the year.
 108          * tm_year is an offset from 1900 and we are interested in the
 109          * 2000-2099 range, so any value less than 100 is invalid.
 110          */
 111         if (tm->tm_year < 100)
 112                 return -EINVAL;
 113
 114         regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
 115         regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
 116         regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
 117         regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
 118         regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
 119         regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
 120         regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
 121
 122         return 0;
 123 }
 124
 125 /*
 126  * Try and match register bits w/ fixed null values to see whether we
 127  * are dealing with an ISL12057. Note: this function is called early
 128  * during init and hence does need mutex protection.
 129  */
 130 static int isl12057_i2c_validate_chip(struct regmap *regmap)
 131 {
 132         u8 regs[ISL12057_MEM_MAP_LEN];
 133         static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
 134                                                        0xc0, 0x60, 0x00, 0x00,
 135                                                        0x00, 0x00, 0x00, 0x00,
 136                                                        0x00, 0x00, 0x60, 0x7c };
 137         int ret, i;
 138
 139         ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
 140         if (ret)
 141                 return ret;
 142
 143         for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
 144                 if (regs[i] & mask[i])  /* check if bits are cleared */
 145                         return -ENODEV;
 146         }
 147
 148         return 0;
 149 }
 150
 151 static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
 152 {
 153         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 154         u8 regs[ISL12057_RTC_SEC_LEN];
 155         int ret;
 156
 157         mutex_lock(&data->lock);
 158         ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
 159                                ISL12057_RTC_SEC_LEN);
 160         mutex_unlock(&data->lock);
 161
 162         if (ret) {
 163                 dev_err(dev, "%s: RTC read failed\n", __func__);
 164                 return ret;
 165         }
 166
 167         isl12057_rtc_regs_to_tm(tm, regs);
 168
 169         return rtc_valid_tm(tm);
 170 }
 171
 172 static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
 173 {
 174         struct isl12057_rtc_data *data = dev_get_drvdata(dev);
 175         u8 regs[ISL12057_RTC_SEC_LEN];
 176         int ret;
 177
 178         ret = isl12057_rtc_tm_to_regs(regs, tm);
 179         if (ret)
 180                 return ret;
 181
 182         mutex_lock(&data->lock);
 183         ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
 184                                 ISL12057_RTC_SEC_LEN);
 185         mutex_unlock(&data->lock);
 186
 187         if (ret)
 188                 dev_err(dev, "%s: RTC write failed\n", __func__);
 189
 190         return ret;
 191 }
 192
 193 /*
 194  * Check current RTC status and enable/disable what needs to be. Return 0 if
 195  * everything went ok and a negative value upon error. Note: this function
 196  * is called early during init and hence does need mutex protection.
 197  */
 198 static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
 199 {
 200         int ret;
 201
 202         /* Enable oscillator if not already running */
 203         ret = regmap_update_bits(regmap, ISL12057_REG_INT,
 204                                  ISL12057_REG_INT_EOSC, 0);
 205         if (ret < 0) {
 206                 dev_err(dev, "Unable to enable oscillator\n");
 207                 return ret;
 208         }
 209
 210         /* Clear oscillator failure bit if needed */
 211         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
 212                                  ISL12057_REG_SR_OSF, 0);
 213         if (ret < 0) {
 214                 dev_err(dev, "Unable to clear oscillator failure bit\n");
 215                 return ret;
 216         }
 217
 218         /* Clear alarm bit if needed */
 219         ret = regmap_update_bits(regmap, ISL12057_REG_SR,
 220                                  ISL12057_REG_SR_A1F, 0);
 221         if (ret < 0) {
 222                 dev_err(dev, "Unable to clear alarm bit\n");
 223                 return ret;
 224         }
 225
 226         return 0;
 227 }
 228
 229 static const struct rtc_class_ops rtc_ops = {
 230         .read_time = isl12057_rtc_read_time,
 231         .set_time = isl12057_rtc_set_time,
 232 };
 233
 234 static struct regmap_config isl12057_rtc_regmap_config = {
 235         .reg_bits = 8,
 236         .val_bits = 8,
 237 };
 238
 239 static int isl12057_probe(struct i2c_client *client,
 240                           const struct i2c_device_id *id)
 241 {
 242         struct device *dev = &client->dev;
 243         struct isl12057_rtc_data *data;
 244         struct rtc_device *rtc;
 245         struct regmap *regmap;
 246         int ret;
 247
 248         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 249                                      I2C_FUNC_SMBUS_BYTE_DATA |
 250                                      I2C_FUNC_SMBUS_I2C_BLOCK))
 251                 return -ENODEV;
 252
 253         regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
 254         if (IS_ERR(regmap)) {
 255                 ret = PTR_ERR(regmap);
 256                 dev_err(dev, "regmap allocation failed: %d\n", ret);
 257                 return ret;
 258         }
 259
 260         ret = isl12057_i2c_validate_chip(regmap);
 261         if (ret)
 262                 return ret;
 263
 264         ret = isl12057_check_rtc_status(dev, regmap);
 265         if (ret)
 266                 return ret;
 267
 268         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 269         if (!data)
 270                 return -ENOMEM;
 271
 272         mutex_init(&data->lock);
 273         data->regmap = regmap;
 274         dev_set_drvdata(dev, data);
 275
 276         rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
 277         return PTR_ERR_OR_ZERO(rtc);
 278 }
 279
 280 #ifdef CONFIG_OF
 281 static const struct of_device_id isl12057_dt_match[] = {
 282         { .compatible = "isl,isl12057" },
 283         { },
 284 };
 285 #endif
 286
 287 static const struct i2c_device_id isl12057_id[] = {
 288         { "isl12057", 0 },
 289         { }
 290 };
 291 MODULE_DEVICE_TABLE(i2c, isl12057_id);
 292
 293 static struct i2c_driver isl12057_driver = {
 294         .driver = {
 295                 .name = DRV_NAME,
 296                 .owner = THIS_MODULE,
 297                 .of_match_table = of_match_ptr(isl12057_dt_match),
 298         },
 299         .probe    = isl12057_probe,
 300         .id_table = isl12057_id,
 301 };
 302 module_i2c_driver(isl12057_driver);
 303
 304 MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
 305 MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
 306 MODULE_LICENSE("GPL");