drivers/rtc/rtc-s3c.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* drivers/rtc/rtc-s3c.c
   3  *
   4  * Copyright (c) 2010 Samsung Electronics Co., Ltd.
   5  *              http://www.samsung.com/
   6  *
   7  * Copyright (c) 2004,2006 Simtec Electronics
   8  *      Ben Dooks, <ben@simtec.co.uk>
   9  *      http://armlinux.simtec.co.uk/
  10  *
  11  * S3C2410/S3C2440/S3C24XX Internal RTC Driver
  12 */
  13
  14 #include <linux/module.h>
  15 #include <linux/fs.h>
  16 #include <linux/string.h>
  17 #include <linux/init.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/rtc.h>
  21 #include <linux/bcd.h>
  22 #include <linux/clk.h>
  23 #include <linux/log2.h>
  24 #include <linux/slab.h>
  25 #include <linux/of.h>
  26 #include <linux/of_device.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/io.h>
  29
  30 #include <asm/irq.h>
  31 #include "rtc-s3c.h"
  32
  33 struct s3c_rtc {
  34         struct device *dev;
  35         struct rtc_device *rtc;
  36
  37         void __iomem *base;
  38         struct clk *rtc_clk;
  39         struct clk *rtc_src_clk;
  40         bool alarm_enabled;
  41
  42         const struct s3c_rtc_data *data;
  43
  44         int irq_alarm;
  45         spinlock_t alarm_lock;
  46
  47         bool wake_en;
  48 };
  49
  50 struct s3c_rtc_data {
  51         bool needs_src_clk;
  52
  53         void (*irq_handler) (struct s3c_rtc *info, int mask);
  54         void (*enable) (struct s3c_rtc *info);
  55         void (*disable) (struct s3c_rtc *info);
  56 };
  57
  58 static int s3c_rtc_enable_clk(struct s3c_rtc *info)
  59 {
  60         int ret;
  61
  62         ret = clk_enable(info->rtc_clk);
  63         if (ret)
  64                 return ret;
  65
  66         if (info->data->needs_src_clk) {
  67                 ret = clk_enable(info->rtc_src_clk);
  68                 if (ret) {
  69                         clk_disable(info->rtc_clk);
  70                         return ret;
  71                 }
  72         }
  73         return 0;
  74 }
  75
  76 static void s3c_rtc_disable_clk(struct s3c_rtc *info)
  77 {
  78         if (info->data->needs_src_clk)
  79                 clk_disable(info->rtc_src_clk);
  80         clk_disable(info->rtc_clk);
  81 }
  82
  83 /* IRQ Handler */
  84 static irqreturn_t s3c_rtc_alarmirq(int irq, void *id)
  85 {
  86         struct s3c_rtc *info = (struct s3c_rtc *)id;
  87
  88         if (info->data->irq_handler)
  89                 info->data->irq_handler(info, S3C2410_INTP_ALM);
  90
  91         return IRQ_HANDLED;
  92 }
  93
  94 /* Update control registers */
  95 static int s3c_rtc_setaie(struct device *dev, unsigned int enabled)
  96 {
  97         struct s3c_rtc *info = dev_get_drvdata(dev);
  98         unsigned long flags;
  99         unsigned int tmp;
 100         int ret;
 101
 102         dev_dbg(info->dev, "%s: aie=%d\n", __func__, enabled);
 103
 104         ret = s3c_rtc_enable_clk(info);
 105         if (ret)
 106                 return ret;
 107
 108         tmp = readb(info->base + S3C2410_RTCALM) & ~S3C2410_RTCALM_ALMEN;
 109
 110         if (enabled)
 111                 tmp |= S3C2410_RTCALM_ALMEN;
 112
 113         writeb(tmp, info->base + S3C2410_RTCALM);
 114
 115         spin_lock_irqsave(&info->alarm_lock, flags);
 116
 117         if (info->alarm_enabled && !enabled)
 118                 s3c_rtc_disable_clk(info);
 119         else if (!info->alarm_enabled && enabled)
 120                 ret = s3c_rtc_enable_clk(info);
 121
 122         info->alarm_enabled = enabled;
 123         spin_unlock_irqrestore(&info->alarm_lock, flags);
 124
 125         s3c_rtc_disable_clk(info);
 126
 127         return ret;
 128 }
 129
 130 /* Read time from RTC and convert it from BCD */
 131 static int s3c_rtc_read_time(struct s3c_rtc *info, struct rtc_time *tm)
 132 {
 133         unsigned int have_retried = 0;
 134         int ret;
 135
 136         ret = s3c_rtc_enable_clk(info);
 137         if (ret)
 138                 return ret;
 139
 140 retry_get_time:
 141         tm->tm_min  = readb(info->base + S3C2410_RTCMIN);
 142         tm->tm_hour = readb(info->base + S3C2410_RTCHOUR);
 143         tm->tm_mday = readb(info->base + S3C2410_RTCDATE);
 144         tm->tm_mon  = readb(info->base + S3C2410_RTCMON);
 145         tm->tm_year = readb(info->base + S3C2410_RTCYEAR);
 146         tm->tm_sec  = readb(info->base + S3C2410_RTCSEC);
 147
 148         /*
 149          * The only way to work out whether the system was mid-update
 150          * when we read it is to check the second counter, and if it
 151          * is zero, then we re-try the entire read
 152          */
 153         if (tm->tm_sec == 0 && !have_retried) {
 154                 have_retried = 1;
 155                 goto retry_get_time;
 156         }
 157
 158         s3c_rtc_disable_clk(info);
 159
 160         tm->tm_sec  = bcd2bin(tm->tm_sec);
 161         tm->tm_min  = bcd2bin(tm->tm_min);
 162         tm->tm_hour = bcd2bin(tm->tm_hour);
 163         tm->tm_mday = bcd2bin(tm->tm_mday);
 164         tm->tm_mon  = bcd2bin(tm->tm_mon);
 165         tm->tm_year = bcd2bin(tm->tm_year);
 166
 167         return 0;
 168 }
 169
 170 /* Convert time to BCD and write it to RTC */
 171 static int s3c_rtc_write_time(struct s3c_rtc *info, const struct rtc_time *tm)
 172 {
 173         int ret;
 174
 175         ret = s3c_rtc_enable_clk(info);
 176         if (ret)
 177                 return ret;
 178
 179         writeb(bin2bcd(tm->tm_sec),  info->base + S3C2410_RTCSEC);
 180         writeb(bin2bcd(tm->tm_min),  info->base + S3C2410_RTCMIN);
 181         writeb(bin2bcd(tm->tm_hour), info->base + S3C2410_RTCHOUR);
 182         writeb(bin2bcd(tm->tm_mday), info->base + S3C2410_RTCDATE);
 183         writeb(bin2bcd(tm->tm_mon),  info->base + S3C2410_RTCMON);
 184         writeb(bin2bcd(tm->tm_year), info->base + S3C2410_RTCYEAR);
 185
 186         s3c_rtc_disable_clk(info);
 187
 188         return 0;
 189 }
 190
 191 static int s3c_rtc_gettime(struct device *dev, struct rtc_time *tm)
 192 {
 193         struct s3c_rtc *info = dev_get_drvdata(dev);
 194         int ret;
 195
 196         ret = s3c_rtc_read_time(info, tm);
 197         if (ret)
 198                 return ret;
 199
 200         /* Convert internal representation to actual date/time */
 201         tm->tm_year += 100;
 202         tm->tm_mon -= 1;
 203
 204         dev_dbg(dev, "read time %ptR\n", tm);
 205         return 0;
 206 }
 207
 208 static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm)
 209 {
 210         struct s3c_rtc *info = dev_get_drvdata(dev);
 211         struct rtc_time rtc_tm = *tm;
 212
 213         dev_dbg(dev, "set time %ptR\n", tm);
 214
 215         /*
 216          * Convert actual date/time to internal representation.
 217          * We get around Y2K by simply not supporting it.
 218          */
 219         rtc_tm.tm_year -= 100;
 220         rtc_tm.tm_mon += 1;
 221
 222         return s3c_rtc_write_time(info, &rtc_tm);
 223 }
 224
 225 static int s3c_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
 226 {
 227         struct s3c_rtc *info = dev_get_drvdata(dev);
 228         struct rtc_time *alm_tm = &alrm->time;
 229         unsigned int alm_en;
 230         int ret;
 231
 232         ret = s3c_rtc_enable_clk(info);
 233         if (ret)
 234                 return ret;
 235
 236         alm_tm->tm_sec  = readb(info->base + S3C2410_ALMSEC);
 237         alm_tm->tm_min  = readb(info->base + S3C2410_ALMMIN);
 238         alm_tm->tm_hour = readb(info->base + S3C2410_ALMHOUR);
 239         alm_tm->tm_mon  = readb(info->base + S3C2410_ALMMON);
 240         alm_tm->tm_mday = readb(info->base + S3C2410_ALMDATE);
 241         alm_tm->tm_year = readb(info->base + S3C2410_ALMYEAR);
 242
 243         alm_en = readb(info->base + S3C2410_RTCALM);
 244
 245         s3c_rtc_disable_clk(info);
 246
 247         alrm->enabled = (alm_en & S3C2410_RTCALM_ALMEN) ? 1 : 0;
 248
 249         dev_dbg(dev, "read alarm %d, %ptR\n", alm_en, alm_tm);
 250
 251         /* decode the alarm enable field */
 252         if (alm_en & S3C2410_RTCALM_SECEN)
 253                 alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
 254
 255         if (alm_en & S3C2410_RTCALM_MINEN)
 256                 alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
 257
 258         if (alm_en & S3C2410_RTCALM_HOUREN)
 259                 alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
 260
 261         if (alm_en & S3C2410_RTCALM_DAYEN)
 262                 alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);
 263
 264         if (alm_en & S3C2410_RTCALM_MONEN) {
 265                 alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon);
 266                 alm_tm->tm_mon -= 1;
 267         }
 268
 269         if (alm_en & S3C2410_RTCALM_YEAREN)
 270                 alm_tm->tm_year = bcd2bin(alm_tm->tm_year);
 271
 272         return 0;
 273 }
 274
 275 static int s3c_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 276 {
 277         struct s3c_rtc *info = dev_get_drvdata(dev);
 278         struct rtc_time *tm = &alrm->time;
 279         unsigned int alrm_en;
 280         int ret;
 281
 282         dev_dbg(dev, "s3c_rtc_setalarm: %d, %ptR\n", alrm->enabled, tm);
 283
 284         ret = s3c_rtc_enable_clk(info);
 285         if (ret)
 286                 return ret;
 287
 288         alrm_en = readb(info->base + S3C2410_RTCALM) & S3C2410_RTCALM_ALMEN;
 289         writeb(0x00, info->base + S3C2410_RTCALM);
 290
 291         if (tm->tm_sec < 60 && tm->tm_sec >= 0) {
 292                 alrm_en |= S3C2410_RTCALM_SECEN;
 293                 writeb(bin2bcd(tm->tm_sec), info->base + S3C2410_ALMSEC);
 294         }
 295
 296         if (tm->tm_min < 60 && tm->tm_min >= 0) {
 297                 alrm_en |= S3C2410_RTCALM_MINEN;
 298                 writeb(bin2bcd(tm->tm_min), info->base + S3C2410_ALMMIN);
 299         }
 300
 301         if (tm->tm_hour < 24 && tm->tm_hour >= 0) {
 302                 alrm_en |= S3C2410_RTCALM_HOUREN;
 303                 writeb(bin2bcd(tm->tm_hour), info->base + S3C2410_ALMHOUR);
 304         }
 305
 306         if (tm->tm_mon < 12 && tm->tm_mon >= 0) {
 307                 alrm_en |= S3C2410_RTCALM_MONEN;
 308                 writeb(bin2bcd(tm->tm_mon + 1), info->base + S3C2410_ALMMON);
 309         }
 310
 311         if (tm->tm_mday <= 31 && tm->tm_mday >= 1) {
 312                 alrm_en |= S3C2410_RTCALM_DAYEN;
 313                 writeb(bin2bcd(tm->tm_mday), info->base + S3C2410_ALMDATE);
 314         }
 315
 316         dev_dbg(dev, "setting S3C2410_RTCALM to %08x\n", alrm_en);
 317
 318         writeb(alrm_en, info->base + S3C2410_RTCALM);
 319
 320         s3c_rtc_setaie(dev, alrm->enabled);
 321
 322         s3c_rtc_disable_clk(info);
 323
 324         return 0;
 325 }
 326
 327 static const struct rtc_class_ops s3c_rtcops = {
 328         .read_time      = s3c_rtc_gettime,
 329         .set_time       = s3c_rtc_settime,
 330         .read_alarm     = s3c_rtc_getalarm,
 331         .set_alarm      = s3c_rtc_setalarm,
 332         .alarm_irq_enable = s3c_rtc_setaie,
 333 };
 334
 335 static void s3c24xx_rtc_enable(struct s3c_rtc *info)
 336 {
 337         unsigned int con, tmp;
 338
 339         con = readw(info->base + S3C2410_RTCCON);
 340         /* re-enable the device, and check it is ok */
 341         if ((con & S3C2410_RTCCON_RTCEN) == 0) {
 342                 dev_info(info->dev, "rtc disabled, re-enabling\n");
 343
 344                 tmp = readw(info->base + S3C2410_RTCCON);
 345                 writew(tmp | S3C2410_RTCCON_RTCEN, info->base + S3C2410_RTCCON);
 346         }
 347
 348         if (con & S3C2410_RTCCON_CNTSEL) {
 349                 dev_info(info->dev, "removing RTCCON_CNTSEL\n");
 350
 351                 tmp = readw(info->base + S3C2410_RTCCON);
 352                 writew(tmp & ~S3C2410_RTCCON_CNTSEL,
 353                        info->base + S3C2410_RTCCON);
 354         }
 355
 356         if (con & S3C2410_RTCCON_CLKRST) {
 357                 dev_info(info->dev, "removing RTCCON_CLKRST\n");
 358
 359                 tmp = readw(info->base + S3C2410_RTCCON);
 360                 writew(tmp & ~S3C2410_RTCCON_CLKRST,
 361                        info->base + S3C2410_RTCCON);
 362         }
 363 }
 364
 365 static void s3c24xx_rtc_disable(struct s3c_rtc *info)
 366 {
 367         unsigned int con;
 368
 369         con = readw(info->base + S3C2410_RTCCON);
 370         con &= ~S3C2410_RTCCON_RTCEN;
 371         writew(con, info->base + S3C2410_RTCCON);
 372
 373         con = readb(info->base + S3C2410_TICNT);
 374         con &= ~S3C2410_TICNT_ENABLE;
 375         writeb(con, info->base + S3C2410_TICNT);
 376 }
 377
 378 static void s3c6410_rtc_disable(struct s3c_rtc *info)
 379 {
 380         unsigned int con;
 381
 382         con = readw(info->base + S3C2410_RTCCON);
 383         con &= ~S3C64XX_RTCCON_TICEN;
 384         con &= ~S3C2410_RTCCON_RTCEN;
 385         writew(con, info->base + S3C2410_RTCCON);
 386 }
 387
 388 static int s3c_rtc_remove(struct platform_device *pdev)
 389 {
 390         struct s3c_rtc *info = platform_get_drvdata(pdev);
 391
 392         s3c_rtc_setaie(info->dev, 0);
 393
 394         if (info->data->needs_src_clk)
 395                 clk_unprepare(info->rtc_src_clk);
 396         clk_unprepare(info->rtc_clk);
 397
 398         return 0;
 399 }
 400
 401 static int s3c_rtc_probe(struct platform_device *pdev)
 402 {
 403         struct s3c_rtc *info = NULL;
 404         int ret;
 405
 406         info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 407         if (!info)
 408                 return -ENOMEM;
 409
 410         info->dev = &pdev->dev;
 411         info->data = of_device_get_match_data(&pdev->dev);
 412         if (!info->data) {
 413                 dev_err(&pdev->dev, "failed getting s3c_rtc_data\n");
 414                 return -EINVAL;
 415         }
 416         spin_lock_init(&info->alarm_lock);
 417
 418         platform_set_drvdata(pdev, info);
 419
 420         info->irq_alarm = platform_get_irq(pdev, 0);
 421         if (info->irq_alarm < 0)
 422                 return info->irq_alarm;
 423
 424         dev_dbg(&pdev->dev, "s3c2410_rtc: alarm irq %d\n", info->irq_alarm);
 425
 426         /* get the memory region */
 427         info->base = devm_platform_ioremap_resource(pdev, 0);
 428         if (IS_ERR(info->base))
 429                 return PTR_ERR(info->base);
 430
 431         info->rtc_clk = devm_clk_get(&pdev->dev, "rtc");
 432         if (IS_ERR(info->rtc_clk)) {
 433                 ret = PTR_ERR(info->rtc_clk);
 434                 if (ret != -EPROBE_DEFER)
 435                         dev_err(&pdev->dev, "failed to find rtc clock\n");
 436                 else
 437                         dev_dbg(&pdev->dev, "probe deferred due to missing rtc clk\n");
 438                 return ret;
 439         }
 440         ret = clk_prepare_enable(info->rtc_clk);
 441         if (ret)
 442                 return ret;
 443
 444         if (info->data->needs_src_clk) {
 445                 info->rtc_src_clk = devm_clk_get(&pdev->dev, "rtc_src");
 446                 if (IS_ERR(info->rtc_src_clk)) {
 447                         ret = dev_err_probe(&pdev->dev, PTR_ERR(info->rtc_src_clk),
 448                                             "failed to find rtc source clock\n");
 449                         goto err_src_clk;
 450                 }
 451                 ret = clk_prepare_enable(info->rtc_src_clk);
 452                 if (ret)
 453                         goto err_src_clk;
 454         }
 455
 456         /* disable RTC enable bits potentially set by the bootloader */
 457         if (info->data->disable)
 458                 info->data->disable(info);
 459
 460         /* check to see if everything is setup correctly */
 461         if (info->data->enable)
 462                 info->data->enable(info);
 463
 464         dev_dbg(&pdev->dev, "s3c2410_rtc: RTCCON=%02x\n",
 465                 readw(info->base + S3C2410_RTCCON));
 466
 467         device_init_wakeup(&pdev->dev, 1);
 468
 469         info->rtc = devm_rtc_allocate_device(&pdev->dev);
 470         if (IS_ERR(info->rtc)) {
 471                 ret = PTR_ERR(info->rtc);
 472                 goto err_nortc;
 473         }
 474
 475         info->rtc->ops = &s3c_rtcops;
 476         info->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 477         info->rtc->range_max = RTC_TIMESTAMP_END_2099;
 478
 479         ret = devm_rtc_register_device(info->rtc);
 480         if (ret)
 481                 goto err_nortc;
 482
 483         ret = devm_request_irq(&pdev->dev, info->irq_alarm, s3c_rtc_alarmirq,
 484                                0, "s3c2410-rtc alarm", info);
 485         if (ret) {
 486                 dev_err(&pdev->dev, "IRQ%d error %d\n", info->irq_alarm, ret);
 487                 goto err_nortc;
 488         }
 489
 490         s3c_rtc_disable_clk(info);
 491
 492         return 0;
 493
 494 err_nortc:
 495         if (info->data->disable)
 496                 info->data->disable(info);
 497
 498         if (info->data->needs_src_clk)
 499                 clk_disable_unprepare(info->rtc_src_clk);
 500 err_src_clk:
 501         clk_disable_unprepare(info->rtc_clk);
 502
 503         return ret;
 504 }
 505
 506 #ifdef CONFIG_PM_SLEEP
 507
 508 static int s3c_rtc_suspend(struct device *dev)
 509 {
 510         struct s3c_rtc *info = dev_get_drvdata(dev);
 511         int ret;
 512
 513         ret = s3c_rtc_enable_clk(info);
 514         if (ret)
 515                 return ret;
 516
 517         if (info->data->disable)
 518                 info->data->disable(info);
 519
 520         if (device_may_wakeup(dev) && !info->wake_en) {
 521                 if (enable_irq_wake(info->irq_alarm) == 0)
 522                         info->wake_en = true;
 523                 else
 524                         dev_err(dev, "enable_irq_wake failed\n");
 525         }
 526
 527         return 0;
 528 }
 529
 530 static int s3c_rtc_resume(struct device *dev)
 531 {
 532         struct s3c_rtc *info = dev_get_drvdata(dev);
 533
 534         if (info->data->enable)
 535                 info->data->enable(info);
 536
 537         s3c_rtc_disable_clk(info);
 538
 539         if (device_may_wakeup(dev) && info->wake_en) {
 540                 disable_irq_wake(info->irq_alarm);
 541                 info->wake_en = false;
 542         }
 543
 544         return 0;
 545 }
 546 #endif
 547 static SIMPLE_DEV_PM_OPS(s3c_rtc_pm_ops, s3c_rtc_suspend, s3c_rtc_resume);
 548
 549 static void s3c24xx_rtc_irq(struct s3c_rtc *info, int mask)
 550 {
 551         rtc_update_irq(info->rtc, 1, RTC_AF | RTC_IRQF);
 552 }
 553
 554 static void s3c6410_rtc_irq(struct s3c_rtc *info, int mask)
 555 {
 556         rtc_update_irq(info->rtc, 1, RTC_AF | RTC_IRQF);
 557         writeb(mask, info->base + S3C2410_INTP);
 558 }
 559
 560 static struct s3c_rtc_data const s3c2410_rtc_data = {
 561         .irq_handler            = s3c24xx_rtc_irq,
 562         .enable                 = s3c24xx_rtc_enable,
 563         .disable                = s3c24xx_rtc_disable,
 564 };
 565
 566 static struct s3c_rtc_data const s3c2416_rtc_data = {
 567         .irq_handler            = s3c24xx_rtc_irq,
 568         .enable                 = s3c24xx_rtc_enable,
 569         .disable                = s3c24xx_rtc_disable,
 570 };
 571
 572 static struct s3c_rtc_data const s3c2443_rtc_data = {
 573         .irq_handler            = s3c24xx_rtc_irq,
 574         .enable                 = s3c24xx_rtc_enable,
 575         .disable                = s3c24xx_rtc_disable,
 576 };
 577
 578 static struct s3c_rtc_data const s3c6410_rtc_data = {
 579         .needs_src_clk          = true,
 580         .irq_handler            = s3c6410_rtc_irq,
 581         .enable                 = s3c24xx_rtc_enable,
 582         .disable                = s3c6410_rtc_disable,
 583 };
 584
 585 static const __maybe_unused struct of_device_id s3c_rtc_dt_match[] = {
 586         {
 587                 .compatible = "samsung,s3c2410-rtc",
 588                 .data = &s3c2410_rtc_data,
 589         }, {
 590                 .compatible = "samsung,s3c2416-rtc",
 591                 .data = &s3c2416_rtc_data,
 592         }, {
 593                 .compatible = "samsung,s3c2443-rtc",
 594                 .data = &s3c2443_rtc_data,
 595         }, {
 596                 .compatible = "samsung,s3c6410-rtc",
 597                 .data = &s3c6410_rtc_data,
 598         }, {
 599                 .compatible = "samsung,exynos3250-rtc",
 600                 .data = &s3c6410_rtc_data,
 601         },
 602         { /* sentinel */ },
 603 };
 604 MODULE_DEVICE_TABLE(of, s3c_rtc_dt_match);
 605
 606 static struct platform_driver s3c_rtc_driver = {
 607         .probe          = s3c_rtc_probe,
 608         .remove         = s3c_rtc_remove,
 609         .driver         = {
 610                 .name   = "s3c-rtc",
 611                 .pm     = &s3c_rtc_pm_ops,
 612                 .of_match_table = of_match_ptr(s3c_rtc_dt_match),
 613         },
 614 };
 615 module_platform_driver(s3c_rtc_driver);
 616
 617 MODULE_DESCRIPTION("Samsung S3C RTC Driver");
 618 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
 619 MODULE_LICENSE("GPL");
 620 MODULE_ALIAS("platform:s3c2410-rtc");