drivers/rtc/rtc-twl.c

   1 /*
   2  * rtc-twl.c -- TWL Real Time Clock interface
   3  *
   4  * Copyright (C) 2007 MontaVista Software, Inc
   5  * Author: Alexandre Rusev <[email protected]>
   6  *
   7  * Based on original TI driver twl4030-rtc.c
   8  *   Copyright (C) 2006 Texas Instruments, Inc.
   9  *
  10  * Based on rtc-omap.c
  11  *   Copyright (C) 2003 MontaVista Software, Inc.
  12  *   Author: George G. Davis <[email protected]> or <[email protected]>
  13  *   Copyright (C) 2006 David Brownell
  14  *
  15  * This program is free software; you can redistribute it and/or
  16  * modify it under the terms of the GNU General Public License
  17  * as published by the Free Software Foundation; either version
  18  * 2 of the License, or (at your option) any later version.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/errno.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/types.h>
  26 #include <linux/rtc.h>
  27 #include <linux/bcd.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/interrupt.h>
  30
  31 #include <linux/i2c/twl.h>
  32
  33
  34 /*
  35  * RTC block register offsets (use TWL_MODULE_RTC)
  36  */
  37 enum {
  38         REG_SECONDS_REG = 0,
  39         REG_MINUTES_REG,
  40         REG_HOURS_REG,
  41         REG_DAYS_REG,
  42         REG_MONTHS_REG,
  43         REG_YEARS_REG,
  44         REG_WEEKS_REG,
  45
  46         REG_ALARM_SECONDS_REG,
  47         REG_ALARM_MINUTES_REG,
  48         REG_ALARM_HOURS_REG,
  49         REG_ALARM_DAYS_REG,
  50         REG_ALARM_MONTHS_REG,
  51         REG_ALARM_YEARS_REG,
  52
  53         REG_RTC_CTRL_REG,
  54         REG_RTC_STATUS_REG,
  55         REG_RTC_INTERRUPTS_REG,
  56
  57         REG_RTC_COMP_LSB_REG,
  58         REG_RTC_COMP_MSB_REG,
  59 };
  60 static const u8 twl4030_rtc_reg_map[] = {
  61         [REG_SECONDS_REG] = 0x00,
  62         [REG_MINUTES_REG] = 0x01,
  63         [REG_HOURS_REG] = 0x02,
  64         [REG_DAYS_REG] = 0x03,
  65         [REG_MONTHS_REG] = 0x04,
  66         [REG_YEARS_REG] = 0x05,
  67         [REG_WEEKS_REG] = 0x06,
  68
  69         [REG_ALARM_SECONDS_REG] = 0x07,
  70         [REG_ALARM_MINUTES_REG] = 0x08,
  71         [REG_ALARM_HOURS_REG] = 0x09,
  72         [REG_ALARM_DAYS_REG] = 0x0A,
  73         [REG_ALARM_MONTHS_REG] = 0x0B,
  74         [REG_ALARM_YEARS_REG] = 0x0C,
  75
  76         [REG_RTC_CTRL_REG] = 0x0D,
  77         [REG_RTC_STATUS_REG] = 0x0E,
  78         [REG_RTC_INTERRUPTS_REG] = 0x0F,
  79
  80         [REG_RTC_COMP_LSB_REG] = 0x10,
  81         [REG_RTC_COMP_MSB_REG] = 0x11,
  82 };
  83 static const u8 twl6030_rtc_reg_map[] = {
  84         [REG_SECONDS_REG] = 0x00,
  85         [REG_MINUTES_REG] = 0x01,
  86         [REG_HOURS_REG] = 0x02,
  87         [REG_DAYS_REG] = 0x03,
  88         [REG_MONTHS_REG] = 0x04,
  89         [REG_YEARS_REG] = 0x05,
  90         [REG_WEEKS_REG] = 0x06,
  91
  92         [REG_ALARM_SECONDS_REG] = 0x08,
  93         [REG_ALARM_MINUTES_REG] = 0x09,
  94         [REG_ALARM_HOURS_REG] = 0x0A,
  95         [REG_ALARM_DAYS_REG] = 0x0B,
  96         [REG_ALARM_MONTHS_REG] = 0x0C,
  97         [REG_ALARM_YEARS_REG] = 0x0D,
  98
  99         [REG_RTC_CTRL_REG] = 0x10,
 100         [REG_RTC_STATUS_REG] = 0x11,
 101         [REG_RTC_INTERRUPTS_REG] = 0x12,
 102
 103         [REG_RTC_COMP_LSB_REG] = 0x13,
 104         [REG_RTC_COMP_MSB_REG] = 0x14,
 105 };
 106
 107 /* RTC_CTRL_REG bitfields */
 108 #define BIT_RTC_CTRL_REG_STOP_RTC_M              0x01
 109 #define BIT_RTC_CTRL_REG_ROUND_30S_M             0x02
 110 #define BIT_RTC_CTRL_REG_AUTO_COMP_M             0x04
 111 #define BIT_RTC_CTRL_REG_MODE_12_24_M            0x08
 112 #define BIT_RTC_CTRL_REG_TEST_MODE_M             0x10
 113 #define BIT_RTC_CTRL_REG_SET_32_COUNTER_M        0x20
 114 #define BIT_RTC_CTRL_REG_GET_TIME_M              0x40
 115
 116 /* RTC_STATUS_REG bitfields */
 117 #define BIT_RTC_STATUS_REG_RUN_M                 0x02
 118 #define BIT_RTC_STATUS_REG_1S_EVENT_M            0x04
 119 #define BIT_RTC_STATUS_REG_1M_EVENT_M            0x08
 120 #define BIT_RTC_STATUS_REG_1H_EVENT_M            0x10
 121 #define BIT_RTC_STATUS_REG_1D_EVENT_M            0x20
 122 #define BIT_RTC_STATUS_REG_ALARM_M               0x40
 123 #define BIT_RTC_STATUS_REG_POWER_UP_M            0x80
 124
 125 /* RTC_INTERRUPTS_REG bitfields */
 126 #define BIT_RTC_INTERRUPTS_REG_EVERY_M           0x03
 127 #define BIT_RTC_INTERRUPTS_REG_IT_TIMER_M        0x04
 128 #define BIT_RTC_INTERRUPTS_REG_IT_ALARM_M        0x08
 129
 130
 131 /* REG_SECONDS_REG through REG_YEARS_REG is how many registers? */
 132 #define ALL_TIME_REGS           6
 133
 134 /*----------------------------------------------------------------------*/
 135 static u8  *rtc_reg_map;
 136
 137 /*
 138  * Supports 1 byte read from TWL RTC register.
 139  */
 140 static int twl_rtc_read_u8(u8 *data, u8 reg)
 141 {
 142         int ret;
 143
 144         ret = twl_i2c_read_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
 145         if (ret < 0)
 146                 pr_err("twl_rtc: Could not read TWL"
 147                        "register %X - error %d\n", reg, ret);
 148         return ret;
 149 }
 150
 151 /*
 152  * Supports 1 byte write to TWL RTC registers.
 153  */
 154 static int twl_rtc_write_u8(u8 data, u8 reg)
 155 {
 156         int ret;
 157
 158         ret = twl_i2c_write_u8(TWL_MODULE_RTC, data, (rtc_reg_map[reg]));
 159         if (ret < 0)
 160                 pr_err("twl_rtc: Could not write TWL"
 161                        "register %X - error %d\n", reg, ret);
 162         return ret;
 163 }
 164
 165 /*
 166  * Cache the value for timer/alarm interrupts register; this is
 167  * only changed by callers holding rtc ops lock (or resume).
 168  */
 169 static unsigned char rtc_irq_bits;
 170
 171 /*
 172  * Enable 1/second update and/or alarm interrupts.
 173  */
 174 static int set_rtc_irq_bit(unsigned char bit)
 175 {
 176         unsigned char val;
 177         int ret;
 178
 179         val = rtc_irq_bits | bit;
 180         val &= ~BIT_RTC_INTERRUPTS_REG_EVERY_M;
 181         ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
 182         if (ret == 0)
 183                 rtc_irq_bits = val;
 184
 185         return ret;
 186 }
 187
 188 /*
 189  * Disable update and/or alarm interrupts.
 190  */
 191 static int mask_rtc_irq_bit(unsigned char bit)
 192 {
 193         unsigned char val;
 194         int ret;
 195
 196         val = rtc_irq_bits & ~bit;
 197         ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
 198         if (ret == 0)
 199                 rtc_irq_bits = val;
 200
 201         return ret;
 202 }
 203
 204 static int twl_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
 205 {
 206         int ret;
 207
 208         if (enabled)
 209                 ret = set_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
 210         else
 211                 ret = mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
 212
 213         return ret;
 214 }
 215
 216 /*
 217  * Gets current TWL RTC time and date parameters.
 218  *
 219  * The RTC's time/alarm representation is not what gmtime(3) requires
 220  * Linux to use:
 221  *
 222  *  - Months are 1..12 vs Linux 0-11
 223  *  - Years are 0..99 vs Linux 1900..N (we assume 21st century)
 224  */
 225 static int twl_rtc_read_time(struct device *dev, struct rtc_time *tm)
 226 {
 227         unsigned char rtc_data[ALL_TIME_REGS + 1];
 228         int ret;
 229         u8 save_control;
 230
 231         ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
 232         if (ret < 0)
 233                 return ret;
 234
 235         save_control |= BIT_RTC_CTRL_REG_GET_TIME_M;
 236
 237         ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
 238         if (ret < 0)
 239                 return ret;
 240
 241         ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
 242                         (rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);
 243
 244         if (ret < 0) {
 245                 dev_err(dev, "rtc_read_time error %d\n", ret);
 246                 return ret;
 247         }
 248
 249         tm->tm_sec = bcd2bin(rtc_data[0]);
 250         tm->tm_min = bcd2bin(rtc_data[1]);
 251         tm->tm_hour = bcd2bin(rtc_data[2]);
 252         tm->tm_mday = bcd2bin(rtc_data[3]);
 253         tm->tm_mon = bcd2bin(rtc_data[4]) - 1;
 254         tm->tm_year = bcd2bin(rtc_data[5]) + 100;
 255
 256         return ret;
 257 }
 258
 259 static int twl_rtc_set_time(struct device *dev, struct rtc_time *tm)
 260 {
 261         unsigned char save_control;
 262         unsigned char rtc_data[ALL_TIME_REGS + 1];
 263         int ret;
 264
 265         rtc_data[1] = bin2bcd(tm->tm_sec);
 266         rtc_data[2] = bin2bcd(tm->tm_min);
 267         rtc_data[3] = bin2bcd(tm->tm_hour);
 268         rtc_data[4] = bin2bcd(tm->tm_mday);
 269         rtc_data[5] = bin2bcd(tm->tm_mon + 1);
 270         rtc_data[6] = bin2bcd(tm->tm_year - 100);
 271
 272         /* Stop RTC while updating the TC registers */
 273         ret = twl_rtc_read_u8(&save_control, REG_RTC_CTRL_REG);
 274         if (ret < 0)
 275                 goto out;
 276
 277         save_control &= ~BIT_RTC_CTRL_REG_STOP_RTC_M;
 278         ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
 279         if (ret < 0)
 280                 goto out;
 281
 282         /* update all the time registers in one shot */
 283         ret = twl_i2c_write(TWL_MODULE_RTC, rtc_data,
 284                 (rtc_reg_map[REG_SECONDS_REG]), ALL_TIME_REGS);
 285         if (ret < 0) {
 286                 dev_err(dev, "rtc_set_time error %d\n", ret);
 287                 goto out;
 288         }
 289
 290         /* Start back RTC */
 291         save_control |= BIT_RTC_CTRL_REG_STOP_RTC_M;
 292         ret = twl_rtc_write_u8(save_control, REG_RTC_CTRL_REG);
 293
 294 out:
 295         return ret;
 296 }
 297
 298 /*
 299  * Gets current TWL RTC alarm time.
 300  */
 301 static int twl_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 302 {
 303         unsigned char rtc_data[ALL_TIME_REGS + 1];
 304         int ret;
 305
 306         ret = twl_i2c_read(TWL_MODULE_RTC, rtc_data,
 307                         (rtc_reg_map[REG_ALARM_SECONDS_REG]), ALL_TIME_REGS);
 308         if (ret < 0) {
 309                 dev_err(dev, "rtc_read_alarm error %d\n", ret);
 310                 return ret;
 311         }
 312
 313         /* some of these fields may be wildcard/"match all" */
 314         alm->time.tm_sec = bcd2bin(rtc_data[0]);
 315         alm->time.tm_min = bcd2bin(rtc_data[1]);
 316         alm->time.tm_hour = bcd2bin(rtc_data[2]);
 317         alm->time.tm_mday = bcd2bin(rtc_data[3]);
 318         alm->time.tm_mon = bcd2bin(rtc_data[4]) - 1;
 319         alm->time.tm_year = bcd2bin(rtc_data[5]) + 100;
 320
 321         /* report cached alarm enable state */
 322         if (rtc_irq_bits & BIT_RTC_INTERRUPTS_REG_IT_ALARM_M)
 323                 alm->enabled = 1;
 324
 325         return ret;
 326 }
 327
 328 static int twl_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 329 {
 330         unsigned char alarm_data[ALL_TIME_REGS + 1];
 331         int ret;
 332
 333         ret = twl_rtc_alarm_irq_enable(dev, 0);
 334         if (ret)
 335                 goto out;
 336
 337         alarm_data[1] = bin2bcd(alm->time.tm_sec);
 338         alarm_data[2] = bin2bcd(alm->time.tm_min);
 339         alarm_data[3] = bin2bcd(alm->time.tm_hour);
 340         alarm_data[4] = bin2bcd(alm->time.tm_mday);
 341         alarm_data[5] = bin2bcd(alm->time.tm_mon + 1);
 342         alarm_data[6] = bin2bcd(alm->time.tm_year - 100);
 343
 344         /* update all the alarm registers in one shot */
 345         ret = twl_i2c_write(TWL_MODULE_RTC, alarm_data,
 346                 (rtc_reg_map[REG_ALARM_SECONDS_REG]), ALL_TIME_REGS);
 347         if (ret) {
 348                 dev_err(dev, "rtc_set_alarm error %d\n", ret);
 349                 goto out;
 350         }
 351
 352         if (alm->enabled)
 353                 ret = twl_rtc_alarm_irq_enable(dev, 1);
 354 out:
 355         return ret;
 356 }
 357
 358 static irqreturn_t twl_rtc_interrupt(int irq, void *rtc)
 359 {
 360         unsigned long events = 0;
 361         int ret = IRQ_NONE;
 362         int res;
 363         u8 rd_reg;
 364
 365         res = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
 366         if (res)
 367                 goto out;
 368         /*
 369          * Figure out source of interrupt: ALARM or TIMER in RTC_STATUS_REG.
 370          * only one (ALARM or RTC) interrupt source may be enabled
 371          * at time, we also could check our results
 372          * by reading RTS_INTERRUPTS_REGISTER[IT_TIMER,IT_ALARM]
 373          */
 374         if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
 375                 events |= RTC_IRQF | RTC_AF;
 376         else
 377                 events |= RTC_IRQF | RTC_UF;
 378
 379         res = twl_rtc_write_u8(rd_reg | BIT_RTC_STATUS_REG_ALARM_M,
 380                                    REG_RTC_STATUS_REG);
 381         if (res)
 382                 goto out;
 383
 384         if (twl_class_is_4030()) {
 385                 /* Clear on Read enabled. RTC_IT bit of TWL4030_INT_PWR_ISR1
 386                  * needs 2 reads to clear the interrupt. One read is done in
 387                  * do_twl_pwrirq(). Doing the second read, to clear
 388                  * the bit.
 389                  *
 390                  * FIXME the reason PWR_ISR1 needs an extra read is that
 391                  * RTC_IF retriggered until we cleared REG_ALARM_M above.
 392                  * But re-reading like this is a bad hack; by doing so we
 393                  * risk wrongly clearing status for some other IRQ (losing
 394                  * the interrupt).  Be smarter about handling RTC_UF ...
 395                  */
 396                 res = twl_i2c_read_u8(TWL4030_MODULE_INT,
 397                         &rd_reg, TWL4030_INT_PWR_ISR1);
 398                 if (res)
 399                         goto out;
 400         }
 401
 402         /* Notify RTC core on event */
 403         rtc_update_irq(rtc, 1, events);
 404
 405         ret = IRQ_HANDLED;
 406 out:
 407         return ret;
 408 }
 409
 410 static struct rtc_class_ops twl_rtc_ops = {
 411         .read_time      = twl_rtc_read_time,
 412         .set_time       = twl_rtc_set_time,
 413         .read_alarm     = twl_rtc_read_alarm,
 414         .set_alarm      = twl_rtc_set_alarm,
 415         .alarm_irq_enable = twl_rtc_alarm_irq_enable,
 416 };
 417
 418 /*----------------------------------------------------------------------*/
 419
 420 static int __devinit twl_rtc_probe(struct platform_device *pdev)
 421 {
 422         struct rtc_device *rtc;
 423         int ret = -EINVAL;
 424         int irq = platform_get_irq(pdev, 0);
 425         u8 rd_reg;
 426
 427         if (irq <= 0)
 428                 goto out1;
 429
 430         ret = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
 431         if (ret < 0)
 432                 goto out1;
 433
 434         if (rd_reg & BIT_RTC_STATUS_REG_POWER_UP_M)
 435                 dev_warn(&pdev->dev, "Power up reset detected.\n");
 436
 437         if (rd_reg & BIT_RTC_STATUS_REG_ALARM_M)
 438                 dev_warn(&pdev->dev, "Pending Alarm interrupt detected.\n");
 439
 440         /* Clear RTC Power up reset and pending alarm interrupts */
 441         ret = twl_rtc_write_u8(rd_reg, REG_RTC_STATUS_REG);
 442         if (ret < 0)
 443                 goto out1;
 444
 445         if (twl_class_is_6030()) {
 446                 twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
 447                         REG_INT_MSK_LINE_A);
 448                 twl6030_interrupt_unmask(TWL6030_RTC_INT_MASK,
 449                         REG_INT_MSK_STS_A);
 450         }
 451
 452         /* Check RTC module status, Enable if it is off */
 453         ret = twl_rtc_read_u8(&rd_reg, REG_RTC_CTRL_REG);
 454         if (ret < 0)
 455                 goto out1;
 456
 457         if (!(rd_reg & BIT_RTC_CTRL_REG_STOP_RTC_M)) {
 458                 dev_info(&pdev->dev, "Enabling TWL-RTC.\n");
 459                 rd_reg = BIT_RTC_CTRL_REG_STOP_RTC_M;
 460                 ret = twl_rtc_write_u8(rd_reg, REG_RTC_CTRL_REG);
 461                 if (ret < 0)
 462                         goto out1;
 463         }
 464
 465         /* init cached IRQ enable bits */
 466         ret = twl_rtc_read_u8(&rtc_irq_bits, REG_RTC_INTERRUPTS_REG);
 467         if (ret < 0)
 468                 goto out1;
 469
 470         rtc = rtc_device_register(pdev->name,
 471                                   &pdev->dev, &twl_rtc_ops, THIS_MODULE);
 472         if (IS_ERR(rtc)) {
 473                 ret = PTR_ERR(rtc);
 474                 dev_err(&pdev->dev, "can't register RTC device, err %ld\n",
 475                         PTR_ERR(rtc));
 476                 goto out1;
 477         }
 478
 479         ret = request_threaded_irq(irq, NULL, twl_rtc_interrupt,
 480                                    IRQF_TRIGGER_RISING,
 481                                    dev_name(&rtc->dev), rtc);
 482         if (ret < 0) {
 483                 dev_err(&pdev->dev, "IRQ is not free.\n");
 484                 goto out2;
 485         }
 486
 487         platform_set_drvdata(pdev, rtc);
 488         return 0;
 489
 490 out2:
 491         rtc_device_unregister(rtc);
 492 out1:
 493         return ret;
 494 }
 495
 496 /*
 497  * Disable all TWL RTC module interrupts.
 498  * Sets status flag to free.
 499  */
 500 static int __devexit twl_rtc_remove(struct platform_device *pdev)
 501 {
 502         /* leave rtc running, but disable irqs */
 503         struct rtc_device *rtc = platform_get_drvdata(pdev);
 504         int irq = platform_get_irq(pdev, 0);
 505
 506         mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
 507         mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
 508         if (twl_class_is_6030()) {
 509                 twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
 510                         REG_INT_MSK_LINE_A);
 511                 twl6030_interrupt_mask(TWL6030_RTC_INT_MASK,
 512                         REG_INT_MSK_STS_A);
 513         }
 514
 515
 516         free_irq(irq, rtc);
 517
 518         rtc_device_unregister(rtc);
 519         platform_set_drvdata(pdev, NULL);
 520         return 0;
 521 }
 522
 523 static void twl_rtc_shutdown(struct platform_device *pdev)
 524 {
 525         /* mask timer interrupts, but leave alarm interrupts on to enable
 526            power-on when alarm is triggered */
 527         mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
 528 }
 529
 530 #ifdef CONFIG_PM
 531
 532 static unsigned char irqstat;
 533
 534 static int twl_rtc_suspend(struct platform_device *pdev, pm_message_t state)
 535 {
 536         irqstat = rtc_irq_bits;
 537
 538         mask_rtc_irq_bit(BIT_RTC_INTERRUPTS_REG_IT_TIMER_M);
 539         return 0;
 540 }
 541
 542 static int twl_rtc_resume(struct platform_device *pdev)
 543 {
 544         set_rtc_irq_bit(irqstat);
 545         return 0;
 546 }
 547
 548 #else
 549 #define twl_rtc_suspend NULL
 550 #define twl_rtc_resume  NULL
 551 #endif
 552
 553 static const struct of_device_id twl_rtc_of_match[] = {
 554         {.compatible = "ti,twl4030-rtc", },
 555         { },
 556 };
 557 MODULE_DEVICE_TABLE(of, twl_rtc_of_match);
 558 MODULE_ALIAS("platform:twl_rtc");
 559
 560 static struct platform_driver twl4030rtc_driver = {
 561         .probe          = twl_rtc_probe,
 562         .remove         = __devexit_p(twl_rtc_remove),
 563         .shutdown       = twl_rtc_shutdown,
 564         .suspend        = twl_rtc_suspend,
 565         .resume         = twl_rtc_resume,
 566         .driver         = {
 567                 .owner          = THIS_MODULE,
 568                 .name           = "twl_rtc",
 569                 .of_match_table = twl_rtc_of_match,
 570         },
 571 };
 572
 573 static int __init twl_rtc_init(void)
 574 {
 575         if (twl_class_is_4030())
 576                 rtc_reg_map = (u8 *) twl4030_rtc_reg_map;
 577         else
 578                 rtc_reg_map = (u8 *) twl6030_rtc_reg_map;
 579
 580         return platform_driver_register(&twl4030rtc_driver);
 581 }
 582 module_init(twl_rtc_init);
 583
 584 static void __exit twl_rtc_exit(void)
 585 {
 586         platform_driver_unregister(&twl4030rtc_driver);
 587 }
 588 module_exit(twl_rtc_exit);
 589
 590 MODULE_AUTHOR("Texas Instruments, MontaVista Software");
 591 MODULE_LICENSE("GPL");