linux/drivers/rtc/rtc-mrst.c
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   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/mrst.h>
  42#include <asm/mrst-vrtc.h>
  43
  44struct 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
  54static const char driver_name[] = "rtc_mrst";
  55
  56#define RTC_IRQMASK     (RTC_PF | RTC_AF)
  57
  58static 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
  65static 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 */
  89static 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
 111static 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
 144static 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
 175static 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
 189static 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
 206static 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
 216static 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 */
 254static 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 defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 270
 271static 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        return 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
 289#else
 290#define mrst_procfs     NULL
 291#endif
 292
 293static const struct rtc_class_ops mrst_rtc_ops = {
 294        .read_time      = mrst_read_time,
 295        .set_time       = mrst_set_time,
 296        .read_alarm     = mrst_read_alarm,
 297        .set_alarm      = mrst_set_alarm,
 298        .proc           = mrst_procfs,
 299        .alarm_irq_enable = mrst_rtc_alarm_irq_enable,
 300};
 301
 302static struct mrst_rtc  mrst_rtc;
 303
 304/*
 305 * When vRTC IRQ is captured by SCU FW, FW will clear the AIE bit in
 306 * Reg B, so no need for this driver to clear it
 307 */
 308static irqreturn_t mrst_rtc_irq(int irq, void *p)
 309{
 310        u8 irqstat;
 311
 312        spin_lock(&rtc_lock);
 313        /* This read will clear all IRQ flags inside Reg C */
 314        irqstat = vrtc_cmos_read(RTC_INTR_FLAGS);
 315        spin_unlock(&rtc_lock);
 316
 317        irqstat &= RTC_IRQMASK | RTC_IRQF;
 318        if (is_intr(irqstat)) {
 319                rtc_update_irq(p, 1, irqstat);
 320                return IRQ_HANDLED;
 321        }
 322        return IRQ_NONE;
 323}
 324
 325static int vrtc_mrst_do_probe(struct device *dev, struct resource *iomem,
 326                              int rtc_irq)
 327{
 328        int retval = 0;
 329        unsigned char rtc_control;
 330
 331        /* There can be only one ... */
 332        if (mrst_rtc.dev)
 333                return -EBUSY;
 334
 335        if (!iomem)
 336                return -ENODEV;
 337
 338        iomem = request_mem_region(iomem->start, resource_size(iomem),
 339                                   driver_name);
 340        if (!iomem) {
 341                dev_dbg(dev, "i/o mem already in use.\n");
 342                return -EBUSY;
 343        }
 344
 345        mrst_rtc.irq = rtc_irq;
 346        mrst_rtc.iomem = iomem;
 347        mrst_rtc.dev = dev;
 348        dev_set_drvdata(dev, &mrst_rtc);
 349
 350        mrst_rtc.rtc = rtc_device_register(driver_name, dev,
 351                                &mrst_rtc_ops, THIS_MODULE);
 352        if (IS_ERR(mrst_rtc.rtc)) {
 353                retval = PTR_ERR(mrst_rtc.rtc);
 354                goto cleanup0;
 355        }
 356
 357        rename_region(iomem, dev_name(&mrst_rtc.rtc->dev));
 358
 359        spin_lock_irq(&rtc_lock);
 360        mrst_irq_disable(&mrst_rtc, RTC_PIE | RTC_AIE);
 361        rtc_control = vrtc_cmos_read(RTC_CONTROL);
 362        spin_unlock_irq(&rtc_lock);
 363
 364        if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY)))
 365                dev_dbg(dev, "TODO: support more than 24-hr BCD mode\n");
 366
 367        if (rtc_irq) {
 368                retval = request_irq(rtc_irq, mrst_rtc_irq,
 369                                0, dev_name(&mrst_rtc.rtc->dev),
 370                                mrst_rtc.rtc);
 371                if (retval < 0) {
 372                        dev_dbg(dev, "IRQ %d is already in use, err %d\n",
 373                                rtc_irq, retval);
 374                        goto cleanup1;
 375                }
 376        }
 377        dev_dbg(dev, "initialised\n");
 378        return 0;
 379
 380cleanup1:
 381        rtc_device_unregister(mrst_rtc.rtc);
 382cleanup0:
 383        dev_set_drvdata(dev, NULL);
 384        mrst_rtc.dev = NULL;
 385        release_mem_region(iomem->start, resource_size(iomem));
 386        dev_err(dev, "rtc-mrst: unable to initialise\n");
 387        return retval;
 388}
 389
 390static void rtc_mrst_do_shutdown(void)
 391{
 392        spin_lock_irq(&rtc_lock);
 393        mrst_irq_disable(&mrst_rtc, RTC_IRQMASK);
 394        spin_unlock_irq(&rtc_lock);
 395}
 396
 397static void rtc_mrst_do_remove(struct device *dev)
 398{
 399        struct mrst_rtc *mrst = dev_get_drvdata(dev);
 400        struct resource *iomem;
 401
 402        rtc_mrst_do_shutdown();
 403
 404        if (mrst->irq)
 405                free_irq(mrst->irq, mrst->rtc);
 406
 407        rtc_device_unregister(mrst->rtc);
 408        mrst->rtc = NULL;
 409
 410        iomem = mrst->iomem;
 411        release_mem_region(iomem->start, resource_size(iomem));
 412        mrst->iomem = NULL;
 413
 414        mrst->dev = NULL;
 415        dev_set_drvdata(dev, NULL);
 416}
 417
 418#ifdef  CONFIG_PM
 419static int mrst_suspend(struct device *dev, pm_message_t mesg)
 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 */
 456static inline int mrst_poweroff(struct device *dev)
 457{
 458        return mrst_suspend(dev, PMSG_HIBERNATE);
 459}
 460
 461static 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#else
 496#define mrst_suspend    NULL
 497#define mrst_resume     NULL
 498
 499static inline int mrst_poweroff(struct device *dev)
 500{
 501        return -ENOSYS;
 502}
 503
 504#endif
 505
 506static int vrtc_mrst_platform_probe(struct platform_device *pdev)
 507{
 508        return vrtc_mrst_do_probe(&pdev->dev,
 509                        platform_get_resource(pdev, IORESOURCE_MEM, 0),
 510                        platform_get_irq(pdev, 0));
 511}
 512
 513static int vrtc_mrst_platform_remove(struct platform_device *pdev)
 514{
 515        rtc_mrst_do_remove(&pdev->dev);
 516        return 0;
 517}
 518
 519static void vrtc_mrst_platform_shutdown(struct platform_device *pdev)
 520{
 521        if (system_state == SYSTEM_POWER_OFF && !mrst_poweroff(&pdev->dev))
 522                return;
 523
 524        rtc_mrst_do_shutdown();
 525}
 526
 527MODULE_ALIAS("platform:vrtc_mrst");
 528
 529static struct platform_driver vrtc_mrst_platform_driver = {
 530        .probe          = vrtc_mrst_platform_probe,
 531        .remove         = vrtc_mrst_platform_remove,
 532        .shutdown       = vrtc_mrst_platform_shutdown,
 533        .driver = {
 534                .name           = (char *) driver_name,
 535                .suspend        = mrst_suspend,
 536                .resume         = mrst_resume,
 537        }
 538};
 539
 540module_platform_driver(vrtc_mrst_platform_driver);
 541
 542MODULE_AUTHOR("Jacob Pan; Feng Tang");
 543MODULE_DESCRIPTION("Driver for Moorestown virtual RTC");
 544MODULE_LICENSE("GPL");
 545
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