1 /* 2 * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C 3 * 4 * Copyright (C) 2009-2011 Freescale Semiconductor. 5 * Author: Jack Lan <jack.lan@freescale.com> 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License as published by the 9 * Free Software Foundation; either version 2 of the License, or (at your 10 * option) any later version. 11 */ 12 /* 13 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as 14 * recommened in .../Documentation/i2c/writing-clients section 15 * "Sending and receiving", using SMBus level communication is preferred. 16 */ 17 18 #include <linux/kernel.h> 19 #include <linux/module.h> 20 #include <linux/interrupt.h> 21 #include <linux/i2c.h> 22 #include <linux/rtc.h> 23 #include <linux/bcd.h> 24 #include <linux/workqueue.h> 25 #include <linux/slab.h> 26 27 #define DS3232_REG_SECONDS 0x00 28 #define DS3232_REG_MINUTES 0x01 29 #define DS3232_REG_HOURS 0x02 30 #define DS3232_REG_AMPM 0x02 31 #define DS3232_REG_DAY 0x03 32 #define DS3232_REG_DATE 0x04 33 #define DS3232_REG_MONTH 0x05 34 #define DS3232_REG_CENTURY 0x05 35 #define DS3232_REG_YEAR 0x06 36 #define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */ 37 #define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */ 38 #define DS3232_REG_CR 0x0E /* Control register */ 39 # define DS3232_REG_CR_nEOSC 0x80 40 # define DS3232_REG_CR_INTCN 0x04 41 # define DS3232_REG_CR_A2IE 0x02 42 # define DS3232_REG_CR_A1IE 0x01 43 44 #define DS3232_REG_SR 0x0F /* control/status register */ 45 # define DS3232_REG_SR_OSF 0x80 46 # define DS3232_REG_SR_BSY 0x04 47 # define DS3232_REG_SR_A2F 0x02 48 # define DS3232_REG_SR_A1F 0x01 49 50 struct ds3232 { 51 struct i2c_client *client; 52 struct rtc_device *rtc; 53 struct work_struct work; 54 55 /* The mutex protects alarm operations, and prevents a race 56 * between the enable_irq() in the workqueue and the free_irq() 57 * in the remove function. 58 */ 59 struct mutex mutex; 60 int exiting; 61 }; 62 63 static struct i2c_driver ds3232_driver; 64 65 static int ds3232_check_rtc_status(struct i2c_client *client) 66 { 67 int ret = 0; 68 int control, stat; 69 70 stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 71 if (stat < 0) 72 return stat; 73 74 if (stat & DS3232_REG_SR_OSF) 75 dev_warn(&client->dev, 76 "oscillator discontinuity flagged, " 77 "time unreliable\n"); 78 79 stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F); 80 81 ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); 82 if (ret < 0) 83 return ret; 84 85 /* If the alarm is pending, clear it before requesting 86 * the interrupt, so an interrupt event isn't reported 87 * before everything is initialized. 88 */ 89 90 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 91 if (control < 0) 92 return control; 93 94 control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE); 95 control |= DS3232_REG_CR_INTCN; 96 97 return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 98 } 99 100 static int ds3232_read_time(struct device *dev, struct rtc_time *time) 101 { 102 struct i2c_client *client = to_i2c_client(dev); 103 int ret; 104 u8 buf[7]; 105 unsigned int year, month, day, hour, minute, second; 106 unsigned int week, twelve_hr, am_pm; 107 unsigned int century, add_century = 0; 108 109 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf); 110 111 if (ret < 0) 112 return ret; 113 if (ret < 7) 114 return -EIO; 115 116 second = buf[0]; 117 minute = buf[1]; 118 hour = buf[2]; 119 week = buf[3]; 120 day = buf[4]; 121 month = buf[5]; 122 year = buf[6]; 123 124 /* Extract additional information for AM/PM and century */ 125 126 twelve_hr = hour & 0x40; 127 am_pm = hour & 0x20; 128 century = month & 0x80; 129 130 /* Write to rtc_time structure */ 131 132 time->tm_sec = bcd2bin(second); 133 time->tm_min = bcd2bin(minute); 134 if (twelve_hr) { 135 /* Convert to 24 hr */ 136 if (am_pm) 137 time->tm_hour = bcd2bin(hour & 0x1F) + 12; 138 else 139 time->tm_hour = bcd2bin(hour & 0x1F); 140 } else { 141 time->tm_hour = bcd2bin(hour); 142 } 143 144 /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */ 145 time->tm_wday = bcd2bin(week) - 1; 146 time->tm_mday = bcd2bin(day); 147 /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */ 148 time->tm_mon = bcd2bin(month & 0x7F) - 1; 149 if (century) 150 add_century = 100; 151 152 time->tm_year = bcd2bin(year) + add_century; 153 154 return rtc_valid_tm(time); 155 } 156 157 static int ds3232_set_time(struct device *dev, struct rtc_time *time) 158 { 159 struct i2c_client *client = to_i2c_client(dev); 160 u8 buf[7]; 161 162 /* Extract time from rtc_time and load into ds3232*/ 163 164 buf[0] = bin2bcd(time->tm_sec); 165 buf[1] = bin2bcd(time->tm_min); 166 buf[2] = bin2bcd(time->tm_hour); 167 /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */ 168 buf[3] = bin2bcd(time->tm_wday + 1); 169 buf[4] = bin2bcd(time->tm_mday); /* Date */ 170 /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */ 171 buf[5] = bin2bcd(time->tm_mon + 1); 172 if (time->tm_year >= 100) { 173 buf[5] |= 0x80; 174 buf[6] = bin2bcd(time->tm_year - 100); 175 } else { 176 buf[6] = bin2bcd(time->tm_year); 177 } 178 179 return i2c_smbus_write_i2c_block_data(client, 180 DS3232_REG_SECONDS, 7, buf); 181 } 182 183 /* 184 * DS3232 has two alarm, we only use alarm1 185 * According to linux specification, only support one-shot alarm 186 * no periodic alarm mode 187 */ 188 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) 189 { 190 struct i2c_client *client = to_i2c_client(dev); 191 struct ds3232 *ds3232 = i2c_get_clientdata(client); 192 int control, stat; 193 int ret; 194 u8 buf[4]; 195 196 mutex_lock(&ds3232->mutex); 197 198 ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 199 if (ret < 0) 200 goto out; 201 stat = ret; 202 ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 203 if (ret < 0) 204 goto out; 205 control = ret; 206 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 207 if (ret < 0) 208 goto out; 209 210 alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F); 211 alarm->time.tm_min = bcd2bin(buf[1] & 0x7F); 212 alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F); 213 alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F); 214 215 alarm->time.tm_mon = -1; 216 alarm->time.tm_year = -1; 217 alarm->time.tm_wday = -1; 218 alarm->time.tm_yday = -1; 219 alarm->time.tm_isdst = -1; 220 221 alarm->enabled = !!(control & DS3232_REG_CR_A1IE); 222 alarm->pending = !!(stat & DS3232_REG_SR_A1F); 223 224 ret = 0; 225 out: 226 mutex_unlock(&ds3232->mutex); 227 return ret; 228 } 229 230 /* 231 * linux rtc-module does not support wday alarm 232 * and only 24h time mode supported indeed 233 */ 234 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 235 { 236 struct i2c_client *client = to_i2c_client(dev); 237 struct ds3232 *ds3232 = i2c_get_clientdata(client); 238 int control, stat; 239 int ret; 240 u8 buf[4]; 241 242 if (client->irq <= 0) 243 return -EINVAL; 244 245 mutex_lock(&ds3232->mutex); 246 247 buf[0] = bin2bcd(alarm->time.tm_sec); 248 buf[1] = bin2bcd(alarm->time.tm_min); 249 buf[2] = bin2bcd(alarm->time.tm_hour); 250 buf[3] = bin2bcd(alarm->time.tm_mday); 251 252 /* clear alarm interrupt enable bit */ 253 ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 254 if (ret < 0) 255 goto out; 256 control = ret; 257 control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE); 258 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 259 if (ret < 0) 260 goto out; 261 262 /* clear any pending alarm flag */ 263 ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 264 if (ret < 0) 265 goto out; 266 stat = ret; 267 stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F); 268 ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); 269 if (ret < 0) 270 goto out; 271 272 ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 273 274 if (alarm->enabled) { 275 control |= DS3232_REG_CR_A1IE; 276 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 277 } 278 out: 279 mutex_unlock(&ds3232->mutex); 280 return ret; 281 } 282 283 static void ds3232_update_alarm(struct i2c_client *client) 284 { 285 struct ds3232 *ds3232 = i2c_get_clientdata(client); 286 int control; 287 int ret; 288 u8 buf[4]; 289 290 mutex_lock(&ds3232->mutex); 291 292 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 293 if (ret < 0) 294 goto unlock; 295 296 buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 297 0x80 : buf[0]; 298 buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 299 0x80 : buf[1]; 300 buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 301 0x80 : buf[2]; 302 buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 303 0x80 : buf[3]; 304 305 ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 306 if (ret < 0) 307 goto unlock; 308 309 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 310 if (control < 0) 311 goto unlock; 312 313 if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF)) 314 /* enable alarm1 interrupt */ 315 control |= DS3232_REG_CR_A1IE; 316 else 317 /* disable alarm1 interrupt */ 318 control &= ~(DS3232_REG_CR_A1IE); 319 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 320 321 unlock: 322 mutex_unlock(&ds3232->mutex); 323 } 324 325 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled) 326 { 327 struct i2c_client *client = to_i2c_client(dev); 328 struct ds3232 *ds3232 = i2c_get_clientdata(client); 329 330 if (client->irq <= 0) 331 return -EINVAL; 332 333 if (enabled) 334 ds3232->rtc->irq_data |= RTC_AF; 335 else 336 ds3232->rtc->irq_data &= ~RTC_AF; 337 338 ds3232_update_alarm(client); 339 return 0; 340 } 341 342 static irqreturn_t ds3232_irq(int irq, void *dev_id) 343 { 344 struct i2c_client *client = dev_id; 345 struct ds3232 *ds3232 = i2c_get_clientdata(client); 346 347 disable_irq_nosync(irq); 348 schedule_work(&ds3232->work); 349 return IRQ_HANDLED; 350 } 351 352 static void ds3232_work(struct work_struct *work) 353 { 354 struct ds3232 *ds3232 = container_of(work, struct ds3232, work); 355 struct i2c_client *client = ds3232->client; 356 int stat, control; 357 358 mutex_lock(&ds3232->mutex); 359 360 stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 361 if (stat < 0) 362 goto unlock; 363 364 if (stat & DS3232_REG_SR_A1F) { 365 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 366 if (control < 0) 367 goto out; 368 /* disable alarm1 interrupt */ 369 control &= ~(DS3232_REG_CR_A1IE); 370 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 371 372 /* clear the alarm pend flag */ 373 stat &= ~DS3232_REG_SR_A1F; 374 i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); 375 376 rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF); 377 } 378 379 out: 380 if (!ds3232->exiting) 381 enable_irq(client->irq); 382 unlock: 383 mutex_unlock(&ds3232->mutex); 384 } 385 386 static const struct rtc_class_ops ds3232_rtc_ops = { 387 .read_time = ds3232_read_time, 388 .set_time = ds3232_set_time, 389 .read_alarm = ds3232_read_alarm, 390 .set_alarm = ds3232_set_alarm, 391 .alarm_irq_enable = ds3232_alarm_irq_enable, 392 }; 393 394 static int ds3232_probe(struct i2c_client *client, 395 const struct i2c_device_id *id) 396 { 397 struct ds3232 *ds3232; 398 int ret; 399 400 ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL); 401 if (!ds3232) 402 return -ENOMEM; 403 404 ds3232->client = client; 405 i2c_set_clientdata(client, ds3232); 406 407 INIT_WORK(&ds3232->work, ds3232_work); 408 mutex_init(&ds3232->mutex); 409 410 ret = ds3232_check_rtc_status(client); 411 if (ret) 412 goto out_free; 413 414 ds3232->rtc = rtc_device_register(client->name, &client->dev, 415 &ds3232_rtc_ops, THIS_MODULE); 416 if (IS_ERR(ds3232->rtc)) { 417 ret = PTR_ERR(ds3232->rtc); 418 dev_err(&client->dev, "unable to register the class device\n"); 419 goto out_irq; 420 } 421 422 if (client->irq >= 0) { 423 ret = request_irq(client->irq, ds3232_irq, 0, 424 "ds3232", client); 425 if (ret) { 426 dev_err(&client->dev, "unable to request IRQ\n"); 427 goto out_free; 428 } 429 } 430 431 return 0; 432 433 out_irq: 434 if (client->irq >= 0) 435 free_irq(client->irq, client); 436 437 out_free: 438 kfree(ds3232); 439 return ret; 440 } 441 442 static int ds3232_remove(struct i2c_client *client) 443 { 444 struct ds3232 *ds3232 = i2c_get_clientdata(client); 445 446 if (client->irq >= 0) { 447 mutex_lock(&ds3232->mutex); 448 ds3232->exiting = 1; 449 mutex_unlock(&ds3232->mutex); 450 451 free_irq(client->irq, client); 452 cancel_work_sync(&ds3232->work); 453 } 454 455 rtc_device_unregister(ds3232->rtc); 456 kfree(ds3232); 457 return 0; 458 } 459 460 static const struct i2c_device_id ds3232_id[] = { 461 { "ds3232", 0 }, 462 { } 463 }; 464 MODULE_DEVICE_TABLE(i2c, ds3232_id); 465 466 static struct i2c_driver ds3232_driver = { 467 .driver = { 468 .name = "rtc-ds3232", 469 .owner = THIS_MODULE, 470 }, 471 .probe = ds3232_probe, 472 .remove = ds3232_remove, 473 .id_table = ds3232_id, 474 }; 475 476 module_i2c_driver(ds3232_driver); 477 478 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>"); 479 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver"); 480 MODULE_LICENSE("GPL"); 481