1 /* 2 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C 3 * 4 * Based on code by Randy Vinson <rvinson@mvista.com>, 5 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>. 6 * 7 * Copyright (C) 2006-2007 Freescale Semiconductor 8 * 9 * 2005 (c) MontaVista Software, Inc. This file is licensed under 10 * the terms of the GNU General Public License version 2. This program 11 * is licensed "as is" without any warranty of any kind, whether express 12 * or implied. 13 */ 14 /* 15 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as 16 * recommened in .../Documentation/i2c/writing-clients section 17 * "Sending and receiving", using SMBus level communication is preferred. 18 */ 19 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/interrupt.h> 23 #include <linux/i2c.h> 24 #include <linux/rtc.h> 25 #include <linux/bcd.h> 26 #include <linux/workqueue.h> 27 28 #define DS1374_REG_TOD0 0x00 /* Time of Day */ 29 #define DS1374_REG_TOD1 0x01 30 #define DS1374_REG_TOD2 0x02 31 #define DS1374_REG_TOD3 0x03 32 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */ 33 #define DS1374_REG_WDALM1 0x05 34 #define DS1374_REG_WDALM2 0x06 35 #define DS1374_REG_CR 0x07 /* Control */ 36 #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */ 37 #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */ 38 #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */ 39 #define DS1374_REG_SR 0x08 /* Status */ 40 #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */ 41 #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */ 42 #define DS1374_REG_TCR 0x09 /* Trickle Charge */ 43 44 static const struct i2c_device_id ds1374_id[] = { 45 { "ds1374", 0 }, 46 { } 47 }; 48 MODULE_DEVICE_TABLE(i2c, ds1374_id); 49 50 struct ds1374 { 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 ds1374_driver; 64 65 static int ds1374_read_rtc(struct i2c_client *client, u32 *time, 66 int reg, int nbytes) 67 { 68 u8 buf[4]; 69 int ret; 70 int i; 71 72 if (nbytes > 4) { 73 WARN_ON(1); 74 return -EINVAL; 75 } 76 77 ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf); 78 79 if (ret < 0) 80 return ret; 81 if (ret < nbytes) 82 return -EIO; 83 84 for (i = nbytes - 1, *time = 0; i >= 0; i--) 85 *time = (*time << 8) | buf[i]; 86 87 return 0; 88 } 89 90 static int ds1374_write_rtc(struct i2c_client *client, u32 time, 91 int reg, int nbytes) 92 { 93 u8 buf[4]; 94 int i; 95 96 if (nbytes > 4) { 97 WARN_ON(1); 98 return -EINVAL; 99 } 100 101 for (i = 0; i < nbytes; i++) { 102 buf[i] = time & 0xff; 103 time >>= 8; 104 } 105 106 return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf); 107 } 108 109 static int ds1374_check_rtc_status(struct i2c_client *client) 110 { 111 int ret = 0; 112 int control, stat; 113 114 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); 115 if (stat < 0) 116 return stat; 117 118 if (stat & DS1374_REG_SR_OSF) 119 dev_warn(&client->dev, 120 "oscillator discontinuity flagged, " 121 "time unreliable\n"); 122 123 stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF); 124 125 ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); 126 if (ret < 0) 127 return ret; 128 129 /* If the alarm is pending, clear it before requesting 130 * the interrupt, so an interrupt event isn't reported 131 * before everything is initialized. 132 */ 133 134 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 135 if (control < 0) 136 return control; 137 138 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); 139 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); 140 } 141 142 static int ds1374_read_time(struct device *dev, struct rtc_time *time) 143 { 144 struct i2c_client *client = to_i2c_client(dev); 145 u32 itime; 146 int ret; 147 148 ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4); 149 if (!ret) 150 rtc_time_to_tm(itime, time); 151 152 return ret; 153 } 154 155 static int ds1374_set_time(struct device *dev, struct rtc_time *time) 156 { 157 struct i2c_client *client = to_i2c_client(dev); 158 unsigned long itime; 159 160 rtc_tm_to_time(time, &itime); 161 return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4); 162 } 163 164 /* The ds1374 has a decrementer for an alarm, rather than a comparator. 165 * If the time of day is changed, then the alarm will need to be 166 * reset. 167 */ 168 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) 169 { 170 struct i2c_client *client = to_i2c_client(dev); 171 struct ds1374 *ds1374 = i2c_get_clientdata(client); 172 u32 now, cur_alarm; 173 int cr, sr; 174 int ret = 0; 175 176 if (client->irq <= 0) 177 return -EINVAL; 178 179 mutex_lock(&ds1374->mutex); 180 181 cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 182 if (ret < 0) 183 goto out; 184 185 sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR); 186 if (ret < 0) 187 goto out; 188 189 ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4); 190 if (ret) 191 goto out; 192 193 ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3); 194 if (ret) 195 goto out; 196 197 rtc_time_to_tm(now + cur_alarm, &alarm->time); 198 alarm->enabled = !!(cr & DS1374_REG_CR_WACE); 199 alarm->pending = !!(sr & DS1374_REG_SR_AF); 200 201 out: 202 mutex_unlock(&ds1374->mutex); 203 return ret; 204 } 205 206 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 207 { 208 struct i2c_client *client = to_i2c_client(dev); 209 struct ds1374 *ds1374 = i2c_get_clientdata(client); 210 struct rtc_time now; 211 unsigned long new_alarm, itime; 212 int cr; 213 int ret = 0; 214 215 if (client->irq <= 0) 216 return -EINVAL; 217 218 ret = ds1374_read_time(dev, &now); 219 if (ret < 0) 220 return ret; 221 222 rtc_tm_to_time(&alarm->time, &new_alarm); 223 rtc_tm_to_time(&now, &itime); 224 225 /* This can happen due to races, in addition to dates that are 226 * truly in the past. To avoid requiring the caller to check for 227 * races, dates in the past are assumed to be in the recent past 228 * (i.e. not something that we'd rather the caller know about via 229 * an error), and the alarm is set to go off as soon as possible. 230 */ 231 if (time_before_eq(new_alarm, itime)) 232 new_alarm = 1; 233 else 234 new_alarm -= itime; 235 236 mutex_lock(&ds1374->mutex); 237 238 ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 239 if (ret < 0) 240 goto out; 241 242 /* Disable any existing alarm before setting the new one 243 * (or lack thereof). */ 244 cr &= ~DS1374_REG_CR_WACE; 245 246 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); 247 if (ret < 0) 248 goto out; 249 250 ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3); 251 if (ret) 252 goto out; 253 254 if (alarm->enabled) { 255 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; 256 cr &= ~DS1374_REG_CR_WDALM; 257 258 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); 259 } 260 261 out: 262 mutex_unlock(&ds1374->mutex); 263 return ret; 264 } 265 266 static irqreturn_t ds1374_irq(int irq, void *dev_id) 267 { 268 struct i2c_client *client = dev_id; 269 struct ds1374 *ds1374 = i2c_get_clientdata(client); 270 271 disable_irq_nosync(irq); 272 schedule_work(&ds1374->work); 273 return IRQ_HANDLED; 274 } 275 276 static void ds1374_work(struct work_struct *work) 277 { 278 struct ds1374 *ds1374 = container_of(work, struct ds1374, work); 279 struct i2c_client *client = ds1374->client; 280 int stat, control; 281 282 mutex_lock(&ds1374->mutex); 283 284 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); 285 if (stat < 0) 286 goto unlock; 287 288 if (stat & DS1374_REG_SR_AF) { 289 stat &= ~DS1374_REG_SR_AF; 290 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); 291 292 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 293 if (control < 0) 294 goto out; 295 296 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); 297 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); 298 299 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); 300 } 301 302 out: 303 if (!ds1374->exiting) 304 enable_irq(client->irq); 305 unlock: 306 mutex_unlock(&ds1374->mutex); 307 } 308 309 static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) 310 { 311 struct i2c_client *client = to_i2c_client(dev); 312 struct ds1374 *ds1374 = i2c_get_clientdata(client); 313 int ret = -ENOIOCTLCMD; 314 315 mutex_lock(&ds1374->mutex); 316 317 switch (cmd) { 318 case RTC_AIE_OFF: 319 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 320 if (ret < 0) 321 goto out; 322 323 ret &= ~DS1374_REG_CR_WACE; 324 325 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); 326 if (ret < 0) 327 goto out; 328 329 break; 330 331 case RTC_AIE_ON: 332 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 333 if (ret < 0) 334 goto out; 335 336 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; 337 ret &= ~DS1374_REG_CR_WDALM; 338 339 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); 340 if (ret < 0) 341 goto out; 342 343 break; 344 } 345 346 out: 347 mutex_unlock(&ds1374->mutex); 348 return ret; 349 } 350 351 static const struct rtc_class_ops ds1374_rtc_ops = { 352 .read_time = ds1374_read_time, 353 .set_time = ds1374_set_time, 354 .read_alarm = ds1374_read_alarm, 355 .set_alarm = ds1374_set_alarm, 356 .ioctl = ds1374_ioctl, 357 }; 358 359 static int ds1374_probe(struct i2c_client *client, 360 const struct i2c_device_id *id) 361 { 362 struct ds1374 *ds1374; 363 int ret; 364 365 ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL); 366 if (!ds1374) 367 return -ENOMEM; 368 369 ds1374->client = client; 370 i2c_set_clientdata(client, ds1374); 371 372 INIT_WORK(&ds1374->work, ds1374_work); 373 mutex_init(&ds1374->mutex); 374 375 ret = ds1374_check_rtc_status(client); 376 if (ret) 377 goto out_free; 378 379 if (client->irq > 0) { 380 ret = request_irq(client->irq, ds1374_irq, 0, 381 "ds1374", client); 382 if (ret) { 383 dev_err(&client->dev, "unable to request IRQ\n"); 384 goto out_free; 385 } 386 387 device_set_wakeup_capable(&client->dev, 1); 388 } 389 390 ds1374->rtc = rtc_device_register(client->name, &client->dev, 391 &ds1374_rtc_ops, THIS_MODULE); 392 if (IS_ERR(ds1374->rtc)) { 393 ret = PTR_ERR(ds1374->rtc); 394 dev_err(&client->dev, "unable to register the class device\n"); 395 goto out_irq; 396 } 397 398 return 0; 399 400 out_irq: 401 if (client->irq > 0) 402 free_irq(client->irq, client); 403 404 out_free: 405 i2c_set_clientdata(client, NULL); 406 kfree(ds1374); 407 return ret; 408 } 409 410 static int __devexit ds1374_remove(struct i2c_client *client) 411 { 412 struct ds1374 *ds1374 = i2c_get_clientdata(client); 413 414 if (client->irq > 0) { 415 mutex_lock(&ds1374->mutex); 416 ds1374->exiting = 1; 417 mutex_unlock(&ds1374->mutex); 418 419 free_irq(client->irq, client); 420 flush_scheduled_work(); 421 } 422 423 rtc_device_unregister(ds1374->rtc); 424 i2c_set_clientdata(client, NULL); 425 kfree(ds1374); 426 return 0; 427 } 428 429 #ifdef CONFIG_PM 430 static int ds1374_suspend(struct i2c_client *client, pm_message_t state) 431 { 432 if (client->irq >= 0 && device_may_wakeup(&client->dev)) 433 enable_irq_wake(client->irq); 434 return 0; 435 } 436 437 static int ds1374_resume(struct i2c_client *client) 438 { 439 if (client->irq >= 0 && device_may_wakeup(&client->dev)) 440 disable_irq_wake(client->irq); 441 return 0; 442 } 443 #else 444 #define ds1374_suspend NULL 445 #define ds1374_resume NULL 446 #endif 447 448 static struct i2c_driver ds1374_driver = { 449 .driver = { 450 .name = "rtc-ds1374", 451 .owner = THIS_MODULE, 452 }, 453 .probe = ds1374_probe, 454 .suspend = ds1374_suspend, 455 .resume = ds1374_resume, 456 .remove = __devexit_p(ds1374_remove), 457 .id_table = ds1374_id, 458 }; 459 460 static int __init ds1374_init(void) 461 { 462 return i2c_add_driver(&ds1374_driver); 463 } 464 465 static void __exit ds1374_exit(void) 466 { 467 i2c_del_driver(&ds1374_driver); 468 } 469 470 module_init(ds1374_init); 471 module_exit(ds1374_exit); 472 473 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); 474 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); 475 MODULE_LICENSE("GPL"); 476