drivers/rtc/rtc-mrst.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * rtc-mrst.c: Driver for Moorestown virtual RTC
   4  *
   5  * (C) Copyright 2009 Intel Corporation
   6  * Author: Jacob Pan (jacob.jun.pan@intel.com)
   7  *         Feng Tang (feng.tang@intel.com)
   8  *
   9  * Note:
  10  * VRTC is emulated by system controller firmware, the real HW
  11  * RTC is located in the PMIC device. SCU FW shadows PMIC RTC
  12  * in a memory mapped IO space that is visible to the host IA
  13  * processor.
  14  *
  15  * This driver is based upon drivers/rtc/rtc-cmos.c
  16  */
  17
  18 /*
  19  * Note:
  20  *  * vRTC only supports binary mode and 24H mode
  21  *  * vRTC only support PIE and AIE, no UIE, and its PIE only happens
  22  *    at 23:59:59pm everyday, no support for adjustable frequency
  23  *  * Alarm function is also limited to hr/min/sec.
  24  */
  25
  26 #include <linux/mod_devicetable.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/kernel.h>
  31 #include <linux/mc146818rtc.h>
  32 #include <linux/module.h>
  33 #include <linux/init.h>
  34 #include <linux/sfi.h>
  35
  36 #include <asm/intel_scu_ipc.h>
  37 #include <asm/intel-mid.h>
  38 #include <asm/intel_mid_vrtc.h>
  39
  40 struct mrst_rtc {
  41         struct rtc_device       *rtc;
  42         struct device           *dev;
  43         int                     irq;
  44
  45         u8                      enabled_wake;
  46         u8                      suspend_ctrl;
  47 };
  48
  49 static const char driver_name[] = "rtc_mrst";
  50
  51 #define RTC_IRQMASK     (RTC_PF | RTC_AF)
  52
  53 static inline int is_intr(u8 rtc_intr)
  54 {
  55         if (!(rtc_intr & RTC_IRQF))
  56                 return 0;
  57         return rtc_intr & RTC_IRQMASK;
  58 }
  59
  60 static inline unsigned char vrtc_is_updating(void)
  61 {
  62         unsigned char uip;
  63         unsigned long flags;
  64
  65         spin_lock_irqsave(&rtc_lock, flags);
  66         uip = (vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP);
  67         spin_unlock_irqrestore(&rtc_lock, flags);
  68         return uip;
  69 }
  70
  71 /*
  72  * rtc_time's year contains the increment over 1900, but vRTC's YEAR
  73  * register can't be programmed to value larger than 0x64, so vRTC
  74  * driver chose to use 1972 (1970 is UNIX time start point) as the base,
  75  * and does the translation at read/write time.
  76  *
  77  * Why not just use 1970 as the offset? it's because using 1972 will
  78  * make it consistent in leap year setting for both vrtc and low-level
  79  * physical rtc devices. Then why not use 1960 as the offset? If we use
  80  * 1960, for a device's first use, its YEAR register is 0 and the system
  81  * year will be parsed as 1960 which is not a valid UNIX time and will
  82  * cause many applications to fail mysteriously.
  83  */
  84 static int mrst_read_time(struct device *dev, struct rtc_time *time)
  85 {
  86         unsigned long flags;
  87
  88         if (vrtc_is_updating())
  89                 msleep(20);
  90
  91         spin_lock_irqsave(&rtc_lock, flags);
  92         time->tm_sec = vrtc_cmos_read(RTC_SECONDS);
  93         time->tm_min = vrtc_cmos_read(RTC_MINUTES);
  94         time->tm_hour = vrtc_cmos_read(RTC_HOURS);
  95         time->tm_mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
  96         time->tm_mon = vrtc_cmos_read(RTC_MONTH);
  97         time->tm_year = vrtc_cmos_read(RTC_YEAR);
  98         spin_unlock_irqrestore(&rtc_lock, flags);
  99
 100         /* Adjust for the 1972/1900 */
 101         time->tm_year += 72;
 102         time->tm_mon--;
 103         return 0;
 104 }
 105
 106 static int mrst_set_time(struct device *dev, struct rtc_time *time)
 107 {
 108         int ret;
 109         unsigned long flags;
 110         unsigned char mon, day, hrs, min, sec;
 111         unsigned int yrs;
 112
 113         yrs = time->tm_year;
 114         mon = time->tm_mon + 1;   /* tm_mon starts at zero */
 115         day = time->tm_mday;
 116         hrs = time->tm_hour;
 117         min = time->tm_min;
 118         sec = time->tm_sec;
 119
 120         if (yrs < 72 || yrs > 172)
 121                 return -EINVAL;
 122         yrs -= 72;
 123
 124         spin_lock_irqsave(&rtc_lock, flags);
 125
 126         vrtc_cmos_write(yrs, RTC_YEAR);
 127         vrtc_cmos_write(mon, RTC_MONTH);
 128         vrtc_cmos_write(day, RTC_DAY_OF_MONTH);
 129         vrtc_cmos_write(hrs, RTC_HOURS);
 130         vrtc_cmos_write(min, RTC_MINUTES);
 131         vrtc_cmos_write(sec, RTC_SECONDS);
 132
 133         spin_unlock_irqrestore(&rtc_lock, flags);
 134
 135         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETTIME);
 136         return ret;
 137 }
 138
 139 static int mrst_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 140 {
 141         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 142         unsigned char rtc_control;
 143
 144         if (mrst->irq <= 0)
 145                 return -EIO;
 146
 147         /* vRTC only supports binary mode */
 148         spin_lock_irq(&rtc_lock);
 149         t->time.tm_sec = vrtc_cmos_read(RTC_SECONDS_ALARM);
 150         t->time.tm_min = vrtc_cmos_read(RTC_MINUTES_ALARM);
 151         t->time.tm_hour = vrtc_cmos_read(RTC_HOURS_ALARM);
 152
 153         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 154         spin_unlock_irq(&rtc_lock);
 155
 156         t->enabled = !!(rtc_control & RTC_AIE);
 157         t->pending = 0;
 158
 159         return 0;
 160 }
 161
 162 static void mrst_checkintr(struct mrst_rtc *mrst, unsigned char rtc_control)
 163 {
 164         unsigned char   rtc_intr;
 165
 166         /*
 167          * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
 168          * allegedly some older rtcs need that to handle irqs properly
 169          */
 170         rtc_intr = vrtc_cmos_read(RTC_INTR_FLAGS);
 171         rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
 172         if (is_intr(rtc_intr))
 173                 rtc_update_irq(mrst->rtc, 1, rtc_intr);
 174 }
 175
 176 static void mrst_irq_enable(struct mrst_rtc *mrst, unsigned char mask)
 177 {
 178         unsigned char   rtc_control;
 179
 180         /*
 181          * Flush any pending IRQ status, notably for update irqs,
 182          * before we enable new IRQs
 183          */
 184         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 185         mrst_checkintr(mrst, rtc_control);
 186
 187         rtc_control |= mask;
 188         vrtc_cmos_write(rtc_control, RTC_CONTROL);
 189
 190         mrst_checkintr(mrst, rtc_control);
 191 }
 192
 193 static void mrst_irq_disable(struct mrst_rtc *mrst, unsigned char mask)
 194 {
 195         unsigned char   rtc_control;
 196
 197         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 198         rtc_control &= ~mask;
 199         vrtc_cmos_write(rtc_control, RTC_CONTROL);
 200         mrst_checkintr(mrst, rtc_control);
 201 }
 202
 203 static int mrst_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 204 {
 205         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 206         unsigned char hrs, min, sec;
 207         int ret = 0;
 208
 209         if (!mrst->irq)
 210                 return -EIO;
 211
 212         hrs = t->time.tm_hour;
 213         min = t->time.tm_min;
 214         sec = t->time.tm_sec;
 215
 216         spin_lock_irq(&rtc_lock);
 217         /* Next rtc irq must not be from previous alarm setting */
 218         mrst_irq_disable(mrst, RTC_AIE);
 219
 220         /* Update alarm */
 221         vrtc_cmos_write(hrs, RTC_HOURS_ALARM);
 222         vrtc_cmos_write(min, RTC_MINUTES_ALARM);
 223         vrtc_cmos_write(sec, RTC_SECONDS_ALARM);
 224
 225         spin_unlock_irq(&rtc_lock);
 226
 227         ret = intel_scu_ipc_simple_command(IPCMSG_VRTC, IPC_CMD_VRTC_SETALARM);
 228         if (ret)
 229                 return ret;
 230
 231         spin_lock_irq(&rtc_lock);
 232         if (t->enabled)
 233                 mrst_irq_enable(mrst, RTC_AIE);
 234
 235         spin_unlock_irq(&rtc_lock);
 236
 237         return 0;
 238 }
 239
 240 /* Currently, the vRTC doesn't support UIE ON/OFF */
 241 static int mrst_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 242 {
 243         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 244         unsigned long   flags;
 245
 246         spin_lock_irqsave(&rtc_lock, flags);
 247         if (enabled)
 248                 mrst_irq_enable(mrst, RTC_AIE);
 249         else
 250                 mrst_irq_disable(mrst, RTC_AIE);
 251         spin_unlock_irqrestore(&rtc_lock, flags);
 252         return 0;
 253 }
 254
 255
 256 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 257
 258 static int mrst_procfs(struct device *dev, struct seq_file *seq)
 259 {
 260         unsigned char   rtc_control;
 261
 262         spin_lock_irq(&rtc_lock);
 263         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 264         spin_unlock_irq(&rtc_lock);
 265
 266         seq_printf(seq,
 267                    "periodic_IRQ\t: %s\n"
 268                    "alarm\t\t: %s\n"
 269                    "BCD\t\t: no\n"
 270                    "periodic_freq\t: daily (not adjustable)\n",
 271                    (rtc_control & RTC_PIE) ? "on" : "off",
 272                    (rtc_control & RTC_AIE) ? "on" : "off");
 273
 274         return 0;
 275 }
 276
 277 #else
 278 #define mrst_procfs     NULL
 279 #endif
 280
 281 static const struct rtc_class_ops mrst_rtc_ops = {
 282         .read_time      = mrst_read_time,
 283         .set_time       = mrst_set_time,
 284         .read_alarm     = mrst_read_alarm,
 285         .set_alarm      = mrst_set_alarm,
 286         .proc           = mrst_procfs,
 287         .alarm_irq_enable = mrst_rtc_alarm_irq_enable,
 288 };
 289
 290 static struct mrst_rtc  mrst_rtc;
 291
 292 /*
 293  * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
 294  * Reg B, so no need for this driver to clear it
 295  */
 296 static irqreturn_t mrst_rtc_irq(int irq, void *p)
 297 {
 298         u8 irqstat;
 299
 300         spin_lock(&rtc_lock);
 301         /* This read will clear all IRQ flags inside Reg C */
 302         irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
 303         spin_unlock(&rtc_lock);
 304
 305         irqstat &= RTC_IRQMASK | RTC_IRQF;
 306         if (is_intr(irqstat)) {
 307                 rtc_update_irq(p, 1, irqstat);
 308                 return IRQ_HANDLED;
 309         }
 310         return IRQ_NONE;
 311 }
 312
 313 static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
 314                               int rtc_irq)
 315 {
 316         int retval = 0;
 317         unsigned char rtc_control;
 318
 319         /* There can be only one ... */
 320         if (mrst_rtc.dev)
 321                 return -EBUSY;
 322
 323         if (!iomem)
 324                 return -ENODEV;
 325
 326         iomem = devm_request_mem_region(dev, iomem->start, resource_size(iomem),
 327                                         driver_name);
 328         if (!iomem) {
 329                 dev_dbg(dev, "i/o mem already in use.\n");
 330                 return -EBUSY;
 331         }
 332
 333         mrst_rtc.irq = rtc_irq;
 334         mrst_rtc.dev = dev;
 335         dev_set_drvdata(dev, &mrst_rtc);
 336
 337         mrst_rtc.rtc = devm_rtc_allocate_device(dev);
 338         if (IS_ERR(mrst_rtc.rtc))
 339                 return PTR_ERR(mrst_rtc.rtc);
 340
 341         mrst_rtc.rtc->ops = &mrst_rtc_ops;
 342
 343         rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
 344
 345         spin_lock_irq(&rtc_lock);
 346         mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
 347         rtc_control = vrtc_cmos_read(RTC_CONTROL);
 348         spin_unlock_irq(&rtc_lock);
 349
 350         if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
 351                 dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
 352
 353         if (rtc_irq) {
 354                 retval = devm_request_irq(dev, rtc_irq, mrst_rtc_irq,
 355                                           0, dev_name(&mrst_rtc.rtc->dev),
 356                                           mrst_rtc.rtc);
 357                 if (retval < 0) {
 358                         dev_dbg(dev, "IRQ %d is already in use, err %d\n",
 359                                 rtc_irq, retval);
 360                         goto cleanup0;
 361                 }
 362         }
 363
 364         retval = rtc_register_device(mrst_rtc.rtc);
 365         if (retval)
 366                 goto cleanup0;
 367
 368         dev_dbg(dev, "initialised\n");
 369         return 0;
 370
 371 cleanup0:
 372         mrst_rtc.dev = NULL;
 373         dev_err(dev, "rtc-mrst: unable to initialise\n");
 374         return retval;
 375 }
 376
 377 static void rtc_mrst_do_shutdown(void)
 378 {
 379         spin_lock_irq(&rtc_lock);
 380         mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
 381         spin_unlock_irq(&rtc_lock);
 382 }
 383
 384 static void rtc_mrst_do_remove(struct device *dev)
 385 {
 386         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 387
 388         rtc_mrst_do_shutdown();
 389
 390         mrst->rtc = NULL;
 391         mrst->dev = NULL;
 392 }
 393
 394 #ifdef CONFIG_PM_SLEEP
 395 static int mrst_suspend(struct device *dev)
 396 {
 397         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 398         unsigned char   tmp;
 399
 400         /* Only the alarm might be a wakeup event source */
 401         spin_lock_irq(&rtc_lock);
 402         mrst->suspend_ctrl = tmp = vrtc_cmos_read(RTC_CONTROL);
 403         if (tmp & (RTC_PIE | RTC_AIE)) {
 404                 unsigned char   mask;
 405
 406                 if (device_may_wakeup(dev))
 407                         mask = RTC_IRQMASK & ~RTC_AIE;
 408                 else
 409                         mask = RTC_IRQMASK;
 410                 tmp &= ~mask;
 411                 vrtc_cmos_write(tmp, RTC_CONTROL);
 412
 413                 mrst_checkintr(mrst, tmp);
 414         }
 415         spin_unlock_irq(&rtc_lock);
 416
 417         if (tmp & RTC_AIE) {
 418                 mrst->enabled_wake = 1;
 419                 enable_irq_wake(mrst->irq);
 420         }
 421
 422         dev_dbg(&mrst_rtc.rtc->dev, "suspend%s, ctrl %02x\n",
 423                         (tmp & RTC_AIE) ? ", alarm may wake" : "",
 424                         tmp);
 425
 426         return 0;
 427 }
 428
 429 /*
 430  * We want RTC alarms to wake us from the deep power saving state
 431  */
 432 static inline int mrst_poweroff(struct device *dev)
 433 {
 434         return mrst_suspend(dev);
 435 }
 436
 437 static int mrst_resume(struct device *dev)
 438 {
 439         struct mrst_rtc *mrst = dev_get_drvdata(dev);
 440         unsigned char tmp = mrst->suspend_ctrl;
 441
 442         /* Re-enable any irqs previously active */
 443         if (tmp & RTC_IRQMASK) {
 444                 unsigned char   mask;
 445
 446                 if (mrst->enabled_wake) {
 447                         disable_irq_wake(mrst->irq);
 448                         mrst->enabled_wake = 0;
 449                 }
 450
 451                 spin_lock_irq(&rtc_lock);
 452                 do {
 453                         vrtc_cmos_write(tmp, RTC_CONTROL);
 454
 455                         mask = vrtc_cmos_read(RTC_INTR_FLAGS);
 456                         mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
 457                         if (!is_intr(mask))
 458                                 break;
 459
 460                         rtc_update_irq(mrst->rtc, 1, mask);
 461                         tmp &= ~RTC_AIE;
 462                 } while (mask & RTC_AIE);
 463                 spin_unlock_irq(&rtc_lock);
 464         }
 465
 466         dev_dbg(&mrst_rtc.rtc->dev, "resume, ctrl %02x\n", tmp);
 467
 468         return 0;
 469 }
 470
 471 static SIMPLE_DEV_PM_OPS(mrst_pm_ops, mrst_suspend, mrst_resume);
 472 #define MRST_PM_OPS (&mrst_pm_ops)
 473
 474 #else
 475 #define MRST_PM_OPS NULL
 476
 477 static inline int mrst_poweroff(struct device *dev)
 478 {
 479         return -ENOSYS;
 480 }
 481
 482 #endif
 483
 484 static int vrtc_mrst_platform_probe(struct platform_device *pdev)
 485 {
 486         return vrtc_mrst_do_probe(&pdev->dev,
 487                         platform_get_resource(pdev, IORESOURCE_MEM, 0),
 488                         platform_get_irq(pdev, 0));
 489 }
 490
 491 static int vrtc_mrst_platform_remove(struct platform_device *pdev)
 492 {
 493         rtc_mrst_do_remove(&pdev->dev);
 494         return 0;
 495 }
 496
 497 static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
 498 {
 499         if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
 500                 return;
 501
 502         rtc_mrst_do_shutdown();
 503 }
 504
 505 MODULE_ALIAS("platform:vrtc_mrst");
 506
 507 static struct platform_driver vrtc_mrst_platform_driver = {
 508         .probe          = vrtc_mrst_platform_probe,
 509         .remove         = vrtc_mrst_platform_remove,
 510         .shutdown       = vrtc_mrst_platform_shutdown,
 511         .driver = {
 512                 .name   = driver_name,
 513                 .pm     = MRST_PM_OPS,
 514         }
 515 };
 516
 517 module_platform_driver(vrtc_mrst_platform_driver);
 518
 519 MODULE_AUTHOR("Jacob Pan; Feng Tang");
 520 MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
 521 MODULE_LICENSE("GPL");