1 /* 2 * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C 3 * 4 * Copyright (C) 2009-2010 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 time->tm_wday = bcd2bin(week); 145 time->tm_mday = bcd2bin(day); 146 time->tm_mon = bcd2bin(month & 0x7F); 147 if (century) 148 add_century = 100; 149 150 time->tm_year = bcd2bin(year) + add_century; 151 152 return rtc_valid_tm(time); 153 } 154 155 static int ds3232_set_time(struct device *dev, struct rtc_time *time) 156 { 157 struct i2c_client *client = to_i2c_client(dev); 158 u8 buf[7]; 159 160 /* Extract time from rtc_time and load into ds3232*/ 161 162 buf[0] = bin2bcd(time->tm_sec); 163 buf[1] = bin2bcd(time->tm_min); 164 buf[2] = bin2bcd(time->tm_hour); 165 buf[3] = bin2bcd(time->tm_wday); /* Day of the week */ 166 buf[4] = bin2bcd(time->tm_mday); /* Date */ 167 buf[5] = bin2bcd(time->tm_mon); 168 if (time->tm_year >= 100) { 169 buf[5] |= 0x80; 170 buf[6] = bin2bcd(time->tm_year - 100); 171 } else { 172 buf[6] = bin2bcd(time->tm_year); 173 } 174 175 return i2c_smbus_write_i2c_block_data(client, 176 DS3232_REG_SECONDS, 7, buf); 177 } 178 179 /* 180 * DS3232 has two alarm, we only use alarm1 181 * According to linux specification, only support one-shot alarm 182 * no periodic alarm mode 183 */ 184 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) 185 { 186 struct i2c_client *client = to_i2c_client(dev); 187 struct ds3232 *ds3232 = i2c_get_clientdata(client); 188 int control, stat; 189 int ret; 190 u8 buf[4]; 191 192 mutex_lock(&ds3232->mutex); 193 194 ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 195 if (ret < 0) 196 goto out; 197 stat = ret; 198 ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 199 if (ret < 0) 200 goto out; 201 control = ret; 202 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 203 if (ret < 0) 204 goto out; 205 206 alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F); 207 alarm->time.tm_min = bcd2bin(buf[1] & 0x7F); 208 alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F); 209 alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F); 210 211 alarm->time.tm_mon = -1; 212 alarm->time.tm_year = -1; 213 alarm->time.tm_wday = -1; 214 alarm->time.tm_yday = -1; 215 alarm->time.tm_isdst = -1; 216 217 alarm->enabled = !!(control & DS3232_REG_CR_A1IE); 218 alarm->pending = !!(stat & DS3232_REG_SR_A1F); 219 220 ret = 0; 221 out: 222 mutex_unlock(&ds3232->mutex); 223 return ret; 224 } 225 226 /* 227 * linux rtc-module does not support wday alarm 228 * and only 24h time mode supported indeed 229 */ 230 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 231 { 232 struct i2c_client *client = to_i2c_client(dev); 233 struct ds3232 *ds3232 = i2c_get_clientdata(client); 234 int control, stat; 235 int ret; 236 u8 buf[4]; 237 238 if (client->irq <= 0) 239 return -EINVAL; 240 241 mutex_lock(&ds3232->mutex); 242 243 buf[0] = bin2bcd(alarm->time.tm_sec); 244 buf[1] = bin2bcd(alarm->time.tm_min); 245 buf[2] = bin2bcd(alarm->time.tm_hour); 246 buf[3] = bin2bcd(alarm->time.tm_mday); 247 248 /* clear alarm interrupt enable bit */ 249 ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 250 if (ret < 0) 251 goto out; 252 control = ret; 253 control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE); 254 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 255 if (ret < 0) 256 goto out; 257 258 /* clear any pending alarm flag */ 259 ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 260 if (ret < 0) 261 goto out; 262 stat = ret; 263 stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F); 264 ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); 265 if (ret < 0) 266 goto out; 267 268 ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 269 270 if (alarm->enabled) { 271 control |= DS3232_REG_CR_A1IE; 272 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 273 } 274 out: 275 mutex_unlock(&ds3232->mutex); 276 return ret; 277 } 278 279 static void ds3232_update_alarm(struct i2c_client *client) 280 { 281 struct ds3232 *ds3232 = i2c_get_clientdata(client); 282 int control; 283 int ret; 284 u8 buf[4]; 285 286 mutex_lock(&ds3232->mutex); 287 288 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 289 if (ret < 0) 290 goto unlock; 291 292 buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 293 0x80 : buf[0]; 294 buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 295 0x80 : buf[1]; 296 buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 297 0x80 : buf[2]; 298 buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 299 0x80 : buf[3]; 300 301 ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); 302 if (ret < 0) 303 goto unlock; 304 305 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 306 if (control < 0) 307 goto unlock; 308 309 if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF)) 310 /* enable alarm1 interrupt */ 311 control |= DS3232_REG_CR_A1IE; 312 else 313 /* disable alarm1 interrupt */ 314 control &= ~(DS3232_REG_CR_A1IE); 315 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 316 317 unlock: 318 mutex_unlock(&ds3232->mutex); 319 } 320 321 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled) 322 { 323 struct i2c_client *client = to_i2c_client(dev); 324 struct ds3232 *ds3232 = i2c_get_clientdata(client); 325 326 if (client->irq <= 0) 327 return -EINVAL; 328 329 if (enabled) 330 ds3232->rtc->irq_data |= RTC_AF; 331 else 332 ds3232->rtc->irq_data &= ~RTC_AF; 333 334 ds3232_update_alarm(client); 335 return 0; 336 } 337 338 static int ds3232_update_irq_enable(struct device *dev, unsigned int enabled) 339 { 340 struct i2c_client *client = to_i2c_client(dev); 341 struct ds3232 *ds3232 = i2c_get_clientdata(client); 342 343 if (client->irq <= 0) 344 return -EINVAL; 345 346 if (enabled) 347 ds3232->rtc->irq_data |= RTC_UF; 348 else 349 ds3232->rtc->irq_data &= ~RTC_UF; 350 351 ds3232_update_alarm(client); 352 return 0; 353 } 354 355 static irqreturn_t ds3232_irq(int irq, void *dev_id) 356 { 357 struct i2c_client *client = dev_id; 358 struct ds3232 *ds3232 = i2c_get_clientdata(client); 359 360 disable_irq_nosync(irq); 361 schedule_work(&ds3232->work); 362 return IRQ_HANDLED; 363 } 364 365 static void ds3232_work(struct work_struct *work) 366 { 367 struct ds3232 *ds3232 = container_of(work, struct ds3232, work); 368 struct i2c_client *client = ds3232->client; 369 int stat, control; 370 371 mutex_lock(&ds3232->mutex); 372 373 stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR); 374 if (stat < 0) 375 goto unlock; 376 377 if (stat & DS3232_REG_SR_A1F) { 378 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); 379 if (control < 0) 380 goto out; 381 /* disable alarm1 interrupt */ 382 control &= ~(DS3232_REG_CR_A1IE); 383 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); 384 385 /* clear the alarm pend flag */ 386 stat &= ~DS3232_REG_SR_A1F; 387 i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); 388 389 rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF); 390 } 391 392 out: 393 if (!ds3232->exiting) 394 enable_irq(client->irq); 395 unlock: 396 mutex_unlock(&ds3232->mutex); 397 } 398 399 static const struct rtc_class_ops ds3232_rtc_ops = { 400 .read_time = ds3232_read_time, 401 .set_time = ds3232_set_time, 402 .read_alarm = ds3232_read_alarm, 403 .set_alarm = ds3232_set_alarm, 404 .alarm_irq_enable = ds3232_alarm_irq_enable, 405 .update_irq_enable = ds3232_update_irq_enable, 406 }; 407 408 static int __devinit ds3232_probe(struct i2c_client *client, 409 const struct i2c_device_id *id) 410 { 411 struct ds3232 *ds3232; 412 int ret; 413 414 ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL); 415 if (!ds3232) 416 return -ENOMEM; 417 418 ds3232->client = client; 419 i2c_set_clientdata(client, ds3232); 420 421 INIT_WORK(&ds3232->work, ds3232_work); 422 mutex_init(&ds3232->mutex); 423 424 ret = ds3232_check_rtc_status(client); 425 if (ret) 426 goto out_free; 427 428 ds3232->rtc = rtc_device_register(client->name, &client->dev, 429 &ds3232_rtc_ops, THIS_MODULE); 430 if (IS_ERR(ds3232->rtc)) { 431 ret = PTR_ERR(ds3232->rtc); 432 dev_err(&client->dev, "unable to register the class device\n"); 433 goto out_irq; 434 } 435 436 if (client->irq >= 0) { 437 ret = request_irq(client->irq, ds3232_irq, 0, 438 "ds3232", client); 439 if (ret) { 440 dev_err(&client->dev, "unable to request IRQ\n"); 441 goto out_free; 442 } 443 } 444 445 return 0; 446 447 out_irq: 448 if (client->irq >= 0) 449 free_irq(client->irq, client); 450 451 out_free: 452 kfree(ds3232); 453 return ret; 454 } 455 456 static int __devexit ds3232_remove(struct i2c_client *client) 457 { 458 struct ds3232 *ds3232 = i2c_get_clientdata(client); 459 460 if (client->irq >= 0) { 461 mutex_lock(&ds3232->mutex); 462 ds3232->exiting = 1; 463 mutex_unlock(&ds3232->mutex); 464 465 free_irq(client->irq, client); 466 flush_scheduled_work(); 467 } 468 469 rtc_device_unregister(ds3232->rtc); 470 kfree(ds3232); 471 return 0; 472 } 473 474 static const struct i2c_device_id ds3232_id[] = { 475 { "ds3232", 0 }, 476 { } 477 }; 478 MODULE_DEVICE_TABLE(i2c, ds3232_id); 479 480 static struct i2c_driver ds3232_driver = { 481 .driver = { 482 .name = "rtc-ds3232", 483 .owner = THIS_MODULE, 484 }, 485 .probe = ds3232_probe, 486 .remove = __devexit_p(ds3232_remove), 487 .id_table = ds3232_id, 488 }; 489 490 static int __init ds3232_init(void) 491 { 492 return i2c_add_driver(&ds3232_driver); 493 } 494 495 static void __exit ds3232_exit(void) 496 { 497 i2c_del_driver(&ds3232_driver); 498 } 499 500 module_init(ds3232_init); 501 module_exit(ds3232_exit); 502 503 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>"); 504 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver"); 505 MODULE_LICENSE("GPL"); 506