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