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/mc146818rtc.h>
  36 #include <linux/module.h>
  37 #include <linux/init.h>
  38 #include <linux/sfi.h>
  39
  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         /* vRTC only supports binary mode */
 153         spin_lock_irq(&rtc_lock);
 154         t->time.tm_sec = vrtc_cmos_read(RTC_SECONDS_ALARM);
 155         t->time.tm_min = vrtc_cmos_read(RTC_MINUTES_ALARM);
 156         t->time.tm_hour = vrtc_cmos_read(RTC_HOURS_ALARM);
 157
 158         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 159         spin_unlock_irq(&rtc_lock);
 160
 161         t->enabled = !!(rtc_control & RTC_AIE);
 162         t->pending = 0;
 163
 164         return 0;
 165 }
 166
 167 static void mrst_checkintr(struct mrst_rtc *mrst, unsigned char rtc_control)
 168 {
 169         unsigned char   rtc_intr;
 170
 171         /*
 172          * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
 173          * allegedly some older rtcs need that to handle irqs properly
 174          */
 175         rtc_intr = vrtc_cmos_read(RTC_INTR_FLAGS);
 176         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
 177         if (is_intr(rtc_intr))
 178                 rtc_update_irq(mrst->rtc, 1, rtc_intr);
 179 }
 180
 181 static void mrst_irq_enable(struct mrst_rtc *mrst, unsigned char mask)
 182 {
 183         unsigned char   rtc_control;
 184
 185         /*
 186          * Flush any pending IRQ status, notably for update irqs,
 187          * before we enable new IRQs
 188          */
 189         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 190         mrst_checkintr(mrst, rtc_control);
 191
 192         rtc_control |= mask;
 193         vrtc_cmos_write(rtc_control, RTC_CONTROL);
 194
 195         mrst_checkintr(mrst, rtc_control);
 196 }
 197
 198 static void mrst_irq_disable(struct mrst_rtc *mrst, unsigned char mask)
 199 {
 200         unsigned char   rtc_control;
 201
 202         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 203         rtc_control &= ~mask;
 204         vrtc_cmos_write(rtc_control, RTC_CONTROL);
 205         mrst_checkintr(mrst, rtc_control);
 206 }
 207
 208 static int mrst_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 209 {
 210         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 211         unsigned char hrs, min, sec;
 212         int ret = 0;
 213
 214         if (!mrst->irq)
 215                 return -EIO;
 216
 217         hrs = t->time.tm_hour;
 218         min = t->time.tm_min;
 219         sec = t->time.tm_sec;
 220
 221         spin_lock_irq(&rtc_lock);
 222         /* Next rtc irq must not be from previous alarm setting */
 223         mrst_irq_disable(mrst, RTC_AIE);
 224
 225         /* Update alarm */
 226         vrtc_cmos_write(hrs, RTC_HOURS_ALARM);
 227         vrtc_cmos_write(min, RTC_MINUTES_ALARM);
 228         vrtc_cmos_write(sec, RTC_SECONDS_ALARM);
 229
 230         spin_unlock_irq(&rtc_lock);
 231
 232         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETALARM);
 233         if (ret)
 234                 return ret;
 235
 236         spin_lock_irq(&rtc_lock);
 237         if (t->enabled)
 238                 mrst_irq_enable(mrst, RTC_AIE);
 239
 240         spin_unlock_irq(&rtc_lock);
 241
 242         return 0;
 243 }
 244
 245 /* Currently, the vRTC doesn't support UIE ON/OFF */
 246 static int mrst_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 247 {
 248         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 249         unsigned long   flags;
 250
 251         spin_lock_irqsave(&rtc_lock, flags);
 252         if (enabled)
 253                 mrst_irq_enable(mrst, RTC_AIE);
 254         else
 255                 mrst_irq_disable(mrst, RTC_AIE);
 256         spin_unlock_irqrestore(&rtc_lock, flags);
 257         return 0;
 258 }
 259
 260
 261 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 262
 263 static int mrst_procfs(struct device *dev, struct seq_file *seq)
 264 {
 265         unsigned char   rtc_control, valid;
 266
 267         spin_lock_irq(&rtc_lock);
 268         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 269         valid = vrtc_cmos_read(RTC_VALID);
 270         spin_unlock_irq(&rtc_lock);
 271
 272         seq_printf(seq,
 273                    "periodic_IRQ\t: %s\n"
 274                    "alarm\t\t: %s\n"
 275                    "BCD\t\t: no\n"
 276                    "periodic_freq\t: daily (not adjustable)\n",
 277                    (rtc_control & RTC_PIE) ? "on" : "off",
 278                    (rtc_control & RTC_AIE) ? "on" : "off");
 279
 280         return 0;
 281 }
 282
 283 #else
 284 #define mrst_procfs     NULL
 285 #endif
 286
 287 static const struct rtc_class_ops mrst_rtc_ops = {
 288         .read_time      = mrst_read_time,
 289         .set_time       = mrst_set_time,
 290         .read_alarm     = mrst_read_alarm,
 291         .set_alarm      = mrst_set_alarm,
 292         .proc           = mrst_procfs,
 293         .alarm_irq_enable = mrst_rtc_alarm_irq_enable,
 294 };
 295
 296 static struct mrst_rtc  mrst_rtc;
 297
 298 /*
 299  * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
 300  * Reg B, so no need for this driver to clear it
 301  */
 302 static irqreturn_t mrst_rtc_irq(int irq, void *p)
 303 {
 304         u8 irqstat;
 305
 306         spin_lock(&rtc_lock);
 307         /* This read will clear all IRQ flags inside Reg C */
 308         irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
 309         spin_unlock(&rtc_lock);
 310
 311         irqstat &= RTC_IRQMASK | RTC_IRQF;
 312         if (is_intr(irqstat)) {
 313                 rtc_update_irq(p, 1, irqstat);
 314                 return IRQ_HANDLED;
 315         }
 316         return IRQ_NONE;
 317 }
 318
 319 static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
 320                               int rtc_irq)
 321 {
 322         int retval = 0;
 323         unsigned char rtc_control;
 324
 325         /* There can be only one ... */
 326         if (mrst_rtc.dev)
 327                 return -EBUSY;
 328
 329         if (!iomem)
 330                 return -ENODEV;
 331
 332         iomem = request_mem_region(iomem->start, resource_size(iomem),
 333                                    driver_name);
 334         if (!iomem) {
 335                 dev_dbg(dev, "i/o mem already in use.\n");
 336                 return -EBUSY;
 337         }
 338
 339         mrst_rtc.irq = rtc_irq;
 340         mrst_rtc.iomem = iomem;
 341         mrst_rtc.dev = dev;
 342         dev_set_drvdata(dev, &mrst_rtc);
 343
 344         mrst_rtc.rtc = rtc_device_register(driver_name, dev,
 345                                 &mrst_rtc_ops, THIS_MODULE);
 346         if (IS_ERR(mrst_rtc.rtc)) {
 347                 retval = PTR_ERR(mrst_rtc.rtc);
 348                 goto cleanup0;
 349         }
 350
 351         rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
 352
 353         spin_lock_irq(&rtc_lock);
 354         mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
 355         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 356         spin_unlock_irq(&rtc_lock);
 357
 358         if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
 359                 dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
 360
 361         if (rtc_irq) {
 362                 retval = request_irq(rtc_irq, mrst_rtc_irq,
 363                                 0, dev_name(&mrst_rtc.rtc->dev),
 364                                 mrst_rtc.rtc);
 365                 if (retval < 0) {
 366                         dev_dbg(dev, "IRQ %d is already in use, err %d\n",
 367                                 rtc_irq, retval);
 368                         goto cleanup1;
 369                 }
 370         }
 371         dev_dbg(dev, "initialised\n");
 372         return 0;
 373
 374 cleanup1:
 375         rtc_device_unregister(mrst_rtc.rtc);
 376 cleanup0:
 377         mrst_rtc.dev = NULL;
 378         release_mem_region(iomem->start, resource_size(iomem));
 379         dev_err(dev, "rtc-mrst: unable to initialise\n");
 380         return retval;
 381 }
 382
 383 static void rtc_mrst_do_shutdown(void)
 384 {
 385         spin_lock_irq(&rtc_lock);
 386         mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
 387         spin_unlock_irq(&rtc_lock);
 388 }
 389
 390 static void rtc_mrst_do_remove(struct device *dev)
 391 {
 392         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 393         struct resource *iomem;
 394
 395         rtc_mrst_do_shutdown();
 396
 397         if (mrst->irq)
 398                 free_irq(mrst->irq, mrst->rtc);
 399
 400         rtc_device_unregister(mrst->rtc);
 401         mrst->rtc = NULL;
 402
 403         iomem = mrst->iomem;
 404         release_mem_region(iomem->start, resource_size(iomem));
 405         mrst->iomem = NULL;
 406
 407         mrst->dev = NULL;
 408 }
 409
 410 #ifdef CONFIG_PM_SLEEP
 411 static int mrst_suspend(struct device *dev)
 412 {
 413         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 414         unsigned char   tmp;
 415
 416         /* Only the alarm might be a wakeup event source */
 417         spin_lock_irq(&rtc_lock);
 418         mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
 419         if (tmp & (RTC_PIE | RTC_AIE)) {
 420                 unsigned char   mask;
 421
 422                 if (device_may_wakeup(dev))
 423                         mask = RTC_IRQMASK & ~RTC_AIE;
 424                 else
 425                         mask = RTC_IRQMASK;
 426                 tmp &= ~mask;
 427                 vrtc_cmos_write(tmp, RTC_CONTROL);
 428
 429                 mrst_checkintr(mrst, tmp);
 430         }
 431         spin_unlock_irq(&rtc_lock);
 432
 433         if (tmp & RTC_AIE) {
 434                 mrst->enabled_wake = 1;
 435                 enable_irq_wake(mrst->irq);
 436         }
 437
 438         dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
 439                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
 440                         tmp);
 441
 442         return 0;
 443 }
 444
 445 /*
 446  * We want RTC alarms to wake us from the deep power saving state
 447  */
 448 static inline int mrst_poweroff(struct device *dev)
 449 {
 450         return mrst_suspend(dev);
 451 }
 452
 453 static int mrst_resume(struct device *dev)
 454 {
 455         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 456         unsigned char tmp = mrst->suspend_ctrl;
 457
 458         /* Re-enable any irqs previously active */
 459         if (tmp & RTC_IRQMASK) {
 460                 unsigned char   mask;
 461
 462                 if (mrst->enabled_wake) {
 463                         disable_irq_wake(mrst->irq);
 464                         mrst->enabled_wake = 0;
 465                 }
 466
 467                 spin_lock_irq(&rtc_lock);
 468                 do {
 469                         vrtc_cmos_write(tmp, RTC_CONTROL);
 470
 471                         mask = vrtc_cmos_read(RTC_INTR_FLAGS);
 472                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
 473                         if (!is_intr(mask))
 474                                 break;
 475
 476                         rtc_update_irq(mrst->rtc, 1, mask);
 477                         tmp &= ~RTC_AIE;
 478                 } while (mask & RTC_AIE);
 479                 spin_unlock_irq(&rtc_lock);
 480         }
 481
 482         dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
 483
 484         return 0;
 485 }
 486
 487 static SIMPLE_DEV_PM_OPS(mrst_pm_ops, mrst_suspend, mrst_resume);
 488 #define MRST_PM_OPS (&mrst_pm_ops)
 489
 490 #else
 491 #define MRST_PM_OPS NULL
 492
 493 static inline int mrst_poweroff(struct device *dev)
 494 {
 495         return -ENOSYS;
 496 }
 497
 498 #endif
 499
 500 static int vrtc_mrst_platform_probe(struct platform_device *pdev)
 501 {
 502         return vrtc_mrst_do_probe(&pdev->dev,
 503                         platform_get_resource(pdev, IORESOURCE_MEM, 0),
 504                         platform_get_irq(pdev, 0));
 505 }
 506
 507 static int vrtc_mrst_platform_remove(struct platform_device *pdev)
 508 {
 509         rtc_mrst_do_remove(&pdev->dev);
 510         return 0;
 511 }
 512
 513 static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
 514 {
 515         if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
 516                 return;
 517
 518         rtc_mrst_do_shutdown();
 519 }
 520
 521 MODULE_ALIAS("platform:vrtc_mrst");
 522
 523 static struct platform_driver vrtc_mrst_platform_driver = {
 524         .probe          = vrtc_mrst_platform_probe,
 525         .remove         = vrtc_mrst_platform_remove,
 526         .shutdown       = vrtc_mrst_platform_shutdown,
 527         .driver = {
 528                 .name   = driver_name,
 529                 .pm     = MRST_PM_OPS,
 530         }
 531 };
 532
 533 module_platform_driver(vrtc_mrst_platform_driver);
 534
 535 MODULE_AUTHOR("Jacob Pan; Feng Tang");
 536 MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
 537 MODULE_LICENSE("GPL");