drivers/rtc/rtc-mrst.c

   1 /*
   2  * rtc-mrst.c: Driver for Moorestown virtual RTC
   3  *
   4  * (C) Copyright 2009 Intel Corporation
   5  * Author: Jacob Pan (jacob.jun.pan@intel.com)
   6  *         Feng Tang (feng.tang@intel.com)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; version 2
  11  * of the License.
  12  *
  13  * Note:
  14  * VRTC is emulated by system controller firmware, the real HW
  15  * RTC is located in the PMIC device. SCU FW shadows PMIC RTC
  16  * in a memory mapped IO space that is visible to the host IA
  17  * processor.
  18  *
  19  * This driver is based upon drivers/rtc/rtc-cmos.c
  20  */
  21
  22 /*
  23  * Note:
  24  *  * vRTC only supports binary mode and 24H mode
  25  *  * vRTC only support PIE and AIE, no UIE, and its PIE only happens
  26  *    at 23:59:59pm everyday, no support for adjustable frequency
  27  *  * Alarm function is also limited to hr/min/sec.
  28  */
  29
  30 #include <linux/mod_devicetable.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/kernel.h>
  35 #include <linux/module.h>
  36 #include <linux/init.h>
  37 #include <linux/sfi.h>
  38
  39 #include <asm-generic/rtc.h>
  40 #include <asm/intel_scu_ipc.h>
  41 #include <asm/intel-mid.h>
  42 #include <asm/intel_mid_vrtc.h>
  43
  44 struct mrst_rtc {
  45         struct rtc_device       *rtc;
  46         struct device           *dev;
  47         int                     irq;
  48         struct resource         *iomem;
  49
  50         u8                      enabled_wake;
  51         u8                      suspend_ctrl;
  52 };
  53
  54 static const char driver_name[] = "rtc_mrst";
  55
  56 #define RTC_IRQMASK     (RTC_PF | RTC_AF)
  57
  58 static inline int is_intr(u8 rtc_intr)
  59 {
  60         if (!(rtc_intr & RTC_IRQF))
  61                 return 0;
  62         return rtc_intr & RTC_IRQMASK;
  63 }
  64
  65 static inline unsigned char vrtc_is_updating(void)
  66 {
  67         unsigned char uip;
  68         unsigned long flags;
  69
  70         spin_lock_irqsave(&rtc_lock, flags);
  71         uip = (vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP);
  72         spin_unlock_irqrestore(&rtc_lock, flags);
  73         return uip;
  74 }
  75
  76 /*
  77  * rtc_time's year contains the increment over 1900, but vRTC's YEAR
  78  * register can't be programmed to value larger than 0x64, so vRTC
  79  * driver chose to use 1972 (1970 is UNIX time start point) as the base,
  80  * and does the translation at read/write time.
  81  *
  82  * Why not just use 1970 as the offset? it's because using 1972 will
  83  * make it consistent in leap year setting for both vrtc and low-level
  84  * physical rtc devices. Then why not use 1960 as the offset? If we use
  85  * 1960, for a device's first use, its YEAR register is 0 and the system
  86  * year will be parsed as 1960 which is not a valid UNIX time and will
  87  * cause many applications to fail mysteriously.
  88  */
  89 static int mrst_read_time(struct device *dev, struct rtc_time *time)
  90 {
  91         unsigned long flags;
  92
  93         if (vrtc_is_updating())
  94                 mdelay(20);
  95
  96         spin_lock_irqsave(&rtc_lock, flags);
  97         time->tm_sec = vrtc_cmos_read(RTC_SECONDS);
  98         time->tm_min = vrtc_cmos_read(RTC_MINUTES);
  99         time->tm_hour = vrtc_cmos_read(RTC_HOURS);
 100         time->tm_mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
 101         time->tm_mon = vrtc_cmos_read(RTC_MONTH);
 102         time->tm_year = vrtc_cmos_read(RTC_YEAR);
 103         spin_unlock_irqrestore(&rtc_lock, flags);
 104
 105         /* Adjust for the 1972/1900 */
 106         time->tm_year += 72;
 107         time->tm_mon--;
 108         return rtc_valid_tm(time);
 109 }
 110
 111 static int mrst_set_time(struct device *dev, struct rtc_time *time)
 112 {
 113         int ret;
 114         unsigned long flags;
 115         unsigned char mon, day, hrs, min, sec;
 116         unsigned int yrs;
 117
 118         yrs = time->tm_year;
 119         mon = time->tm_mon + 1;   /* tm_mon starts at zero */
 120         day = time->tm_mday;
 121         hrs = time->tm_hour;
 122         min = time->tm_min;
 123         sec = time->tm_sec;
 124
 125         if (yrs < 72 || yrs > 138)
 126                 return -EINVAL;
 127         yrs -= 72;
 128
 129         spin_lock_irqsave(&rtc_lock, flags);
 130
 131         vrtc_cmos_write(yrs, RTC_YEAR);
 132         vrtc_cmos_write(mon, RTC_MONTH);
 133         vrtc_cmos_write(day, RTC_DAY_OF_MONTH);
 134         vrtc_cmos_write(hrs, RTC_HOURS);
 135         vrtc_cmos_write(min, RTC_MINUTES);
 136         vrtc_cmos_write(sec, RTC_SECONDS);
 137
 138         spin_unlock_irqrestore(&rtc_lock, flags);
 139
 140         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETTIME);
 141         return ret;
 142 }
 143
 144 static int mrst_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 145 {
 146         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 147         unsigned char rtc_control;
 148
 149         if (mrst->irq <= 0)
 150                 return -EIO;
 151
 152         /* Basic alarms only support hour, minute, and seconds fields.
 153          * Some also support day and month, for alarms up to a year in
 154          * the future.
 155          */
 156         t->time.tm_mday = -1;
 157         t->time.tm_mon = -1;
 158         t->time.tm_year = -1;
 159
 160         /* vRTC only supports binary mode */
 161         spin_lock_irq(&rtc_lock);
 162         t->time.tm_sec = vrtc_cmos_read(RTC_SECONDS_ALARM);
 163         t->time.tm_min = vrtc_cmos_read(RTC_MINUTES_ALARM);
 164         t->time.tm_hour = vrtc_cmos_read(RTC_HOURS_ALARM);
 165
 166         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 167         spin_unlock_irq(&rtc_lock);
 168
 169         t->enabled = !!(rtc_control & RTC_AIE);
 170         t->pending = 0;
 171
 172         return 0;
 173 }
 174
 175 static void mrst_checkintr(struct mrst_rtc *mrst, unsigned char rtc_control)
 176 {
 177         unsigned char   rtc_intr;
 178
 179         /*
 180          * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
 181          * allegedly some older rtcs need that to handle irqs properly
 182          */
 183         rtc_intr = vrtc_cmos_read(RTC_INTR_FLAGS);
 184         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
 185         if (is_intr(rtc_intr))
 186                 rtc_update_irq(mrst->rtc, 1, rtc_intr);
 187 }
 188
 189 static void mrst_irq_enable(struct mrst_rtc *mrst, unsigned char mask)
 190 {
 191         unsigned char   rtc_control;
 192
 193         /*
 194          * Flush any pending IRQ status, notably for update irqs,
 195          * before we enable new IRQs
 196          */
 197         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 198         mrst_checkintr(mrst, rtc_control);
 199
 200         rtc_control |= mask;
 201         vrtc_cmos_write(rtc_control, RTC_CONTROL);
 202
 203         mrst_checkintr(mrst, rtc_control);
 204 }
 205
 206 static void mrst_irq_disable(struct mrst_rtc *mrst, unsigned char mask)
 207 {
 208         unsigned char   rtc_control;
 209
 210         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 211         rtc_control &= ~mask;
 212         vrtc_cmos_write(rtc_control, RTC_CONTROL);
 213         mrst_checkintr(mrst, rtc_control);
 214 }
 215
 216 static int mrst_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 217 {
 218         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 219         unsigned char hrs, min, sec;
 220         int ret = 0;
 221
 222         if (!mrst->irq)
 223                 return -EIO;
 224
 225         hrs = t->time.tm_hour;
 226         min = t->time.tm_min;
 227         sec = t->time.tm_sec;
 228
 229         spin_lock_irq(&rtc_lock);
 230         /* Next rtc irq must not be from previous alarm setting */
 231         mrst_irq_disable(mrst, RTC_AIE);
 232
 233         /* Update alarm */
 234         vrtc_cmos_write(hrs, RTC_HOURS_ALARM);
 235         vrtc_cmos_write(min, RTC_MINUTES_ALARM);
 236         vrtc_cmos_write(sec, RTC_SECONDS_ALARM);
 237
 238         spin_unlock_irq(&rtc_lock);
 239
 240         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETALARM);
 241         if (ret)
 242                 return ret;
 243
 244         spin_lock_irq(&rtc_lock);
 245         if (t->enabled)
 246                 mrst_irq_enable(mrst, RTC_AIE);
 247
 248         spin_unlock_irq(&rtc_lock);
 249
 250         return 0;
 251 }
 252
 253 /* Currently, the vRTC doesn't support UIE ON/OFF */
 254 static int mrst_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 255 {
 256         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 257         unsigned long   flags;
 258
 259         spin_lock_irqsave(&rtc_lock, flags);
 260         if (enabled)
 261                 mrst_irq_enable(mrst, RTC_AIE);
 262         else
 263                 mrst_irq_disable(mrst, RTC_AIE);
 264         spin_unlock_irqrestore(&rtc_lock, flags);
 265         return 0;
 266 }
 267
 268
 269 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 270
 271 static int mrst_procfs(struct device *dev, struct seq_file *seq)
 272 {
 273         unsigned char   rtc_control, valid;
 274
 275         spin_lock_irq(&rtc_lock);
 276         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 277         valid = vrtc_cmos_read(RTC_VALID);
 278         spin_unlock_irq(&rtc_lock);
 279
 280         seq_printf(seq,
 281                    "periodic_IRQ\t: %s\n"
 282                    "alarm\t\t: %s\n"
 283                    "BCD\t\t: no\n"
 284                    "periodic_freq\t: daily (not adjustable)\n",
 285                    (rtc_control & RTC_PIE) ? "on" : "off",
 286                    (rtc_control & RTC_AIE) ? "on" : "off");
 287
 288         return 0;
 289 }
 290
 291 #else
 292 #define mrst_procfs     NULL
 293 #endif
 294
 295 static const struct rtc_class_ops mrst_rtc_ops = {
 296         .read_time      = mrst_read_time,
 297         .set_time       = mrst_set_time,
 298         .read_alarm     = mrst_read_alarm,
 299         .set_alarm      = mrst_set_alarm,
 300         .proc           = mrst_procfs,
 301         .alarm_irq_enable = mrst_rtc_alarm_irq_enable,
 302 };
 303
 304 static struct mrst_rtc  mrst_rtc;
 305
 306 /*
 307  * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
 308  * Reg B, so no need for this driver to clear it
 309  */
 310 static irqreturn_t mrst_rtc_irq(int irq, void *p)
 311 {
 312         u8 irqstat;
 313
 314         spin_lock(&rtc_lock);
 315         /* This read will clear all IRQ flags inside Reg C */
 316         irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
 317         spin_unlock(&rtc_lock);
 318
 319         irqstat &= RTC_IRQMASK | RTC_IRQF;
 320         if (is_intr(irqstat)) {
 321                 rtc_update_irq(p, 1, irqstat);
 322                 return IRQ_HANDLED;
 323         }
 324         return IRQ_NONE;
 325 }
 326
 327 static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
 328                               int rtc_irq)
 329 {
 330         int retval = 0;
 331         unsigned char rtc_control;
 332
 333         /* There can be only one ... */
 334         if (mrst_rtc.dev)
 335                 return -EBUSY;
 336
 337         if (!iomem)
 338                 return -ENODEV;
 339
 340         iomem = request_mem_region(iomem->start, resource_size(iomem),
 341                                    driver_name);
 342         if (!iomem) {
 343                 dev_dbg(dev, "i/o mem already in use.\n");
 344                 return -EBUSY;
 345         }
 346
 347         mrst_rtc.irq = rtc_irq;
 348         mrst_rtc.iomem = iomem;
 349         mrst_rtc.dev = dev;
 350         dev_set_drvdata(dev, &mrst_rtc);
 351
 352         mrst_rtc.rtc = rtc_device_register(driver_name, dev,
 353                                 &mrst_rtc_ops, THIS_MODULE);
 354         if (IS_ERR(mrst_rtc.rtc)) {
 355                 retval = PTR_ERR(mrst_rtc.rtc);
 356                 goto cleanup0;
 357         }
 358
 359         rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
 360
 361         spin_lock_irq(&rtc_lock);
 362         mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
 363         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 364         spin_unlock_irq(&rtc_lock);
 365
 366         if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
 367                 dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
 368
 369         if (rtc_irq) {
 370                 retval = request_irq(rtc_irq, mrst_rtc_irq,
 371                                 0, dev_name(&mrst_rtc.rtc->dev),
 372                                 mrst_rtc.rtc);
 373                 if (retval < 0) {
 374                         dev_dbg(dev, "IRQ %d is already in use, err %d\n",
 375                                 rtc_irq, retval);
 376                         goto cleanup1;
 377                 }
 378         }
 379         dev_dbg(dev, "initialised\n");
 380         return 0;
 381
 382 cleanup1:
 383         rtc_device_unregister(mrst_rtc.rtc);
 384 cleanup0:
 385         mrst_rtc.dev = NULL;
 386         release_mem_region(iomem->start, resource_size(iomem));
 387         dev_err(dev, "rtc-mrst: unable to initialise\n");
 388         return retval;
 389 }
 390
 391 static void rtc_mrst_do_shutdown(void)
 392 {
 393         spin_lock_irq(&rtc_lock);
 394         mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
 395         spin_unlock_irq(&rtc_lock);
 396 }
 397
 398 static void rtc_mrst_do_remove(struct device *dev)
 399 {
 400         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 401         struct resource *iomem;
 402
 403         rtc_mrst_do_shutdown();
 404
 405         if (mrst->irq)
 406                 free_irq(mrst->irq, mrst->rtc);
 407
 408         rtc_device_unregister(mrst->rtc);
 409         mrst->rtc = NULL;
 410
 411         iomem = mrst->iomem;
 412         release_mem_region(iomem->start, resource_size(iomem));
 413         mrst->iomem = NULL;
 414
 415         mrst->dev = NULL;
 416 }
 417
 418 #ifdef CONFIG_PM_SLEEP
 419 static int mrst_suspend(struct device *dev)
 420 {
 421         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 422         unsigned char   tmp;
 423
 424         /* Only the alarm might be a wakeup event source */
 425         spin_lock_irq(&rtc_lock);
 426         mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
 427         if (tmp & (RTC_PIE | RTC_AIE)) {
 428                 unsigned char   mask;
 429
 430                 if (device_may_wakeup(dev))
 431                         mask = RTC_IRQMASK & ~RTC_AIE;
 432                 else
 433                         mask = RTC_IRQMASK;
 434                 tmp &= ~mask;
 435                 vrtc_cmos_write(tmp, RTC_CONTROL);
 436
 437                 mrst_checkintr(mrst, tmp);
 438         }
 439         spin_unlock_irq(&rtc_lock);
 440
 441         if (tmp & RTC_AIE) {
 442                 mrst->enabled_wake = 1;
 443                 enable_irq_wake(mrst->irq);
 444         }
 445
 446         dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
 447                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
 448                         tmp);
 449
 450         return 0;
 451 }
 452
 453 /*
 454  * We want RTC alarms to wake us from the deep power saving state
 455  */
 456 static inline int mrst_poweroff(struct device *dev)
 457 {
 458         return mrst_suspend(dev);
 459 }
 460
 461 static int mrst_resume(struct device *dev)
 462 {
 463         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 464         unsigned char tmp = mrst->suspend_ctrl;
 465
 466         /* Re-enable any irqs previously active */
 467         if (tmp & RTC_IRQMASK) {
 468                 unsigned char   mask;
 469
 470                 if (mrst->enabled_wake) {
 471                         disable_irq_wake(mrst->irq);
 472                         mrst->enabled_wake = 0;
 473                 }
 474
 475                 spin_lock_irq(&rtc_lock);
 476                 do {
 477                         vrtc_cmos_write(tmp, RTC_CONTROL);
 478
 479                         mask = vrtc_cmos_read(RTC_INTR_FLAGS);
 480                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
 481                         if (!is_intr(mask))
 482                                 break;
 483
 484                         rtc_update_irq(mrst->rtc, 1, mask);
 485                         tmp &= ~RTC_AIE;
 486                 } while (mask & RTC_AIE);
 487                 spin_unlock_irq(&rtc_lock);
 488         }
 489
 490         dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
 491
 492         return 0;
 493 }
 494
 495 static SIMPLE_DEV_PM_OPS(mrst_pm_ops, mrst_suspend, mrst_resume);
 496 #define MRST_PM_OPS (&mrst_pm_ops)
 497
 498 #else
 499 #define MRST_PM_OPS NULL
 500
 501 static inline int mrst_poweroff(struct device *dev)
 502 {
 503         return -ENOSYS;
 504 }
 505
 506 #endif
 507
 508 static int vrtc_mrst_platform_probe(struct platform_device *pdev)
 509 {
 510         return vrtc_mrst_do_probe(&pdev->dev,
 511                         platform_get_resource(pdev, IORESOURCE_MEM, 0),
 512                         platform_get_irq(pdev, 0));
 513 }
 514
 515 static int vrtc_mrst_platform_remove(struct platform_device *pdev)
 516 {
 517         rtc_mrst_do_remove(&pdev->dev);
 518         return 0;
 519 }
 520
 521 static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
 522 {
 523         if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
 524                 return;
 525
 526         rtc_mrst_do_shutdown();
 527 }
 528
 529 MODULE_ALIAS("platform:vrtc_mrst");
 530
 531 static struct platform_driver vrtc_mrst_platform_driver = {
 532         .probe          = vrtc_mrst_platform_probe,
 533         .remove         = vrtc_mrst_platform_remove,
 534         .shutdown       = vrtc_mrst_platform_shutdown,
 535         .driver = {
 536                 .name   = driver_name,
 537                 .pm     = MRST_PM_OPS,
 538         }
 539 };
 540
 541 module_platform_driver(vrtc_mrst_platform_driver);
 542
 543 MODULE_AUTHOR("Jacob Pan; Feng Tang");
 544 MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
 545 MODULE_LICENSE("GPL");