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 #include <linux/slab.h> 28 #include <linux/pm.h> 29 30 #define DS1374_REG_TOD0 0x00 /* Time of Day */ 31 #define DS1374_REG_TOD1 0x01 32 #define DS1374_REG_TOD2 0x02 33 #define DS1374_REG_TOD3 0x03 34 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */ 35 #define DS1374_REG_WDALM1 0x05 36 #define DS1374_REG_WDALM2 0x06 37 #define DS1374_REG_CR 0x07 /* Control */ 38 #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */ 39 #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */ 40 #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */ 41 #define DS1374_REG_SR 0x08 /* Status */ 42 #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */ 43 #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */ 44 #define DS1374_REG_TCR 0x09 /* Trickle Charge */ 45 46 static const struct i2c_device_id ds1374_id[] = { 47 { "ds1374", 0 }, 48 { } 49 }; 50 MODULE_DEVICE_TABLE(i2c, ds1374_id); 51 52 struct ds1374 { 53 struct i2c_client *client; 54 struct rtc_device *rtc; 55 struct work_struct work; 56 57 /* The mutex protects alarm operations, and prevents a race 58 * between the enable_irq() in the workqueue and the free_irq() 59 * in the remove function. 60 */ 61 struct mutex mutex; 62 int exiting; 63 }; 64 65 static struct i2c_driver ds1374_driver; 66 67 static int ds1374_read_rtc(struct i2c_client *client, u32 *time, 68 int reg, int nbytes) 69 { 70 u8 buf[4]; 71 int ret; 72 int i; 73 74 if (nbytes > 4) { 75 WARN_ON(1); 76 return -EINVAL; 77 } 78 79 ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf); 80 81 if (ret < 0) 82 return ret; 83 if (ret < nbytes) 84 return -EIO; 85 86 for (i = nbytes - 1, *time = 0; i >= 0; i--) 87 *time = (*time << 8) | buf[i]; 88 89 return 0; 90 } 91 92 static int ds1374_write_rtc(struct i2c_client *client, u32 time, 93 int reg, int nbytes) 94 { 95 u8 buf[4]; 96 int i; 97 98 if (nbytes > 4) { 99 WARN_ON(1); 100 return -EINVAL; 101 } 102 103 for (i = 0; i < nbytes; i++) { 104 buf[i] = time & 0xff; 105 time >>= 8; 106 } 107 108 return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf); 109 } 110 111 static int ds1374_check_rtc_status(struct i2c_client *client) 112 { 113 int ret = 0; 114 int control, stat; 115 116 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); 117 if (stat < 0) 118 return stat; 119 120 if (stat & DS1374_REG_SR_OSF) 121 dev_warn(&client->dev, 122 "oscillator discontinuity flagged, " 123 "time unreliable\n"); 124 125 stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF); 126 127 ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); 128 if (ret < 0) 129 return ret; 130 131 /* If the alarm is pending, clear it before requesting 132 * the interrupt, so an interrupt event isn't reported 133 * before everything is initialized. 134 */ 135 136 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 137 if (control < 0) 138 return control; 139 140 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); 141 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); 142 } 143 144 static int ds1374_read_time(struct device *dev, struct rtc_time *time) 145 { 146 struct i2c_client *client = to_i2c_client(dev); 147 u32 itime; 148 int ret; 149 150 ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4); 151 if (!ret) 152 rtc_time_to_tm(itime, time); 153 154 return ret; 155 } 156 157 static int ds1374_set_time(struct device *dev, struct rtc_time *time) 158 { 159 struct i2c_client *client = to_i2c_client(dev); 160 unsigned long itime; 161 162 rtc_tm_to_time(time, &itime); 163 return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4); 164 } 165 166 /* The ds1374 has a decrementer for an alarm, rather than a comparator. 167 * If the time of day is changed, then the alarm will need to be 168 * reset. 169 */ 170 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) 171 { 172 struct i2c_client *client = to_i2c_client(dev); 173 struct ds1374 *ds1374 = i2c_get_clientdata(client); 174 u32 now, cur_alarm; 175 int cr, sr; 176 int ret = 0; 177 178 if (client->irq <= 0) 179 return -EINVAL; 180 181 mutex_lock(&ds1374->mutex); 182 183 cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 184 if (ret < 0) 185 goto out; 186 187 sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR); 188 if (ret < 0) 189 goto out; 190 191 ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4); 192 if (ret) 193 goto out; 194 195 ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3); 196 if (ret) 197 goto out; 198 199 rtc_time_to_tm(now + cur_alarm, &alarm->time); 200 alarm->enabled = !!(cr & DS1374_REG_CR_WACE); 201 alarm->pending = !!(sr & DS1374_REG_SR_AF); 202 203 out: 204 mutex_unlock(&ds1374->mutex); 205 return ret; 206 } 207 208 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) 209 { 210 struct i2c_client *client = to_i2c_client(dev); 211 struct ds1374 *ds1374 = i2c_get_clientdata(client); 212 struct rtc_time now; 213 unsigned long new_alarm, itime; 214 int cr; 215 int ret = 0; 216 217 if (client->irq <= 0) 218 return -EINVAL; 219 220 ret = ds1374_read_time(dev, &now); 221 if (ret < 0) 222 return ret; 223 224 rtc_tm_to_time(&alarm->time, &new_alarm); 225 rtc_tm_to_time(&now, &itime); 226 227 /* This can happen due to races, in addition to dates that are 228 * truly in the past. To avoid requiring the caller to check for 229 * races, dates in the past are assumed to be in the recent past 230 * (i.e. not something that we'd rather the caller know about via 231 * an error), and the alarm is set to go off as soon as possible. 232 */ 233 if (time_before_eq(new_alarm, itime)) 234 new_alarm = 1; 235 else 236 new_alarm -= itime; 237 238 mutex_lock(&ds1374->mutex); 239 240 ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 241 if (ret < 0) 242 goto out; 243 244 /* Disable any existing alarm before setting the new one 245 * (or lack thereof). */ 246 cr &= ~DS1374_REG_CR_WACE; 247 248 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); 249 if (ret < 0) 250 goto out; 251 252 ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3); 253 if (ret) 254 goto out; 255 256 if (alarm->enabled) { 257 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; 258 cr &= ~DS1374_REG_CR_WDALM; 259 260 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); 261 } 262 263 out: 264 mutex_unlock(&ds1374->mutex); 265 return ret; 266 } 267 268 static irqreturn_t ds1374_irq(int irq, void *dev_id) 269 { 270 struct i2c_client *client = dev_id; 271 struct ds1374 *ds1374 = i2c_get_clientdata(client); 272 273 disable_irq_nosync(irq); 274 schedule_work(&ds1374->work); 275 return IRQ_HANDLED; 276 } 277 278 static void ds1374_work(struct work_struct *work) 279 { 280 struct ds1374 *ds1374 = container_of(work, struct ds1374, work); 281 struct i2c_client *client = ds1374->client; 282 int stat, control; 283 284 mutex_lock(&ds1374->mutex); 285 286 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); 287 if (stat < 0) 288 goto unlock; 289 290 if (stat & DS1374_REG_SR_AF) { 291 stat &= ~DS1374_REG_SR_AF; 292 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); 293 294 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 295 if (control < 0) 296 goto out; 297 298 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); 299 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); 300 301 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); 302 } 303 304 out: 305 if (!ds1374->exiting) 306 enable_irq(client->irq); 307 unlock: 308 mutex_unlock(&ds1374->mutex); 309 } 310 311 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled) 312 { 313 struct i2c_client *client = to_i2c_client(dev); 314 struct ds1374 *ds1374 = i2c_get_clientdata(client); 315 int ret; 316 317 mutex_lock(&ds1374->mutex); 318 319 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); 320 if (ret < 0) 321 goto out; 322 323 if (enabled) { 324 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; 325 ret &= ~DS1374_REG_CR_WDALM; 326 } else { 327 ret &= ~DS1374_REG_CR_WACE; 328 } 329 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); 330 331 out: 332 mutex_unlock(&ds1374->mutex); 333 return ret; 334 } 335 336 static const struct rtc_class_ops ds1374_rtc_ops = { 337 .read_time = ds1374_read_time, 338 .set_time = ds1374_set_time, 339 .read_alarm = ds1374_read_alarm, 340 .set_alarm = ds1374_set_alarm, 341 .alarm_irq_enable = ds1374_alarm_irq_enable, 342 }; 343 344 static int ds1374_probe(struct i2c_client *client, 345 const struct i2c_device_id *id) 346 { 347 struct ds1374 *ds1374; 348 int ret; 349 350 ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL); 351 if (!ds1374) 352 return -ENOMEM; 353 354 ds1374->client = client; 355 i2c_set_clientdata(client, ds1374); 356 357 INIT_WORK(&ds1374->work, ds1374_work); 358 mutex_init(&ds1374->mutex); 359 360 ret = ds1374_check_rtc_status(client); 361 if (ret) 362 goto out_free; 363 364 if (client->irq > 0) { 365 ret = request_irq(client->irq, ds1374_irq, 0, 366 "ds1374", client); 367 if (ret) { 368 dev_err(&client->dev, "unable to request IRQ\n"); 369 goto out_free; 370 } 371 372 device_set_wakeup_capable(&client->dev, 1); 373 } 374 375 ds1374->rtc = rtc_device_register(client->name, &client->dev, 376 &ds1374_rtc_ops, THIS_MODULE); 377 if (IS_ERR(ds1374->rtc)) { 378 ret = PTR_ERR(ds1374->rtc); 379 dev_err(&client->dev, "unable to register the class device\n"); 380 goto out_irq; 381 } 382 383 return 0; 384 385 out_irq: 386 if (client->irq > 0) 387 free_irq(client->irq, client); 388 389 out_free: 390 kfree(ds1374); 391 return ret; 392 } 393 394 static int __devexit ds1374_remove(struct i2c_client *client) 395 { 396 struct ds1374 *ds1374 = i2c_get_clientdata(client); 397 398 if (client->irq > 0) { 399 mutex_lock(&ds1374->mutex); 400 ds1374->exiting = 1; 401 mutex_unlock(&ds1374->mutex); 402 403 free_irq(client->irq, client); 404 cancel_work_sync(&ds1374->work); 405 } 406 407 rtc_device_unregister(ds1374->rtc); 408 kfree(ds1374); 409 return 0; 410 } 411 412 #ifdef CONFIG_PM 413 static int ds1374_suspend(struct device *dev) 414 { 415 struct i2c_client *client = to_i2c_client(dev); 416 417 if (client->irq >= 0 && device_may_wakeup(&client->dev)) 418 enable_irq_wake(client->irq); 419 return 0; 420 } 421 422 static int ds1374_resume(struct device *dev) 423 { 424 struct i2c_client *client = to_i2c_client(dev); 425 426 if (client->irq >= 0 && device_may_wakeup(&client->dev)) 427 disable_irq_wake(client->irq); 428 return 0; 429 } 430 431 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume); 432 433 #define DS1374_PM (&ds1374_pm) 434 #else 435 #define DS1374_PM NULL 436 #endif 437 438 static struct i2c_driver ds1374_driver = { 439 .driver = { 440 .name = "rtc-ds1374", 441 .owner = THIS_MODULE, 442 .pm = DS1374_PM, 443 }, 444 .probe = ds1374_probe, 445 .remove = __devexit_p(ds1374_remove), 446 .id_table = ds1374_id, 447 }; 448 449 module_i2c_driver(ds1374_driver); 450 451 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); 452 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); 453 MODULE_LICENSE("GPL"); 454