drivers/rtc/rtc-wm831x.c

   1 /*
   2  *      Real Time Clock driver for Wolfson Microelectronics WM831x
   3  *
   4  *      Copyright (C) 2009 Wolfson Microelectronics PLC.
   5  *
   6  *  Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
   7  *
   8  *  This program is free software; you can redistribute  it and/or modify it
   9  *  under  the terms of  the GNU General  Public License as published by the
  10  *  Free Software Foundation;  either version 2 of the  License, or (at your
  11  *  option) any later version.
  12  *
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/time.h>
  18 #include <linux/rtc.h>
  19 #include <linux/slab.h>
  20 #include <linux/bcd.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/ioctl.h>
  23 #include <linux/completion.h>
  24 #include <linux/mfd/wm831x/core.h>
  25 #include <linux/delay.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/random.h>
  28
  29 /*
  30  * R16416 (0x4020) - RTC Write Counter
  31  */
  32 #define WM831X_RTC_WR_CNT_MASK                  0xFFFF  /* RTC_WR_CNT - [15:0] */
  33 #define WM831X_RTC_WR_CNT_SHIFT                      0  /* RTC_WR_CNT - [15:0] */
  34 #define WM831X_RTC_WR_CNT_WIDTH                     16  /* RTC_WR_CNT - [15:0] */
  35
  36 /*
  37  * R16417 (0x4021) - RTC Time 1
  38  */
  39 #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
  40 #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
  41 #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
  42
  43 /*
  44  * R16418 (0x4022) - RTC Time 2
  45  */
  46 #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
  47 #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
  48 #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
  49
  50 /*
  51  * R16419 (0x4023) - RTC Alarm 1
  52  */
  53 #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
  54 #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
  55 #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
  56
  57 /*
  58  * R16420 (0x4024) - RTC Alarm 2
  59  */
  60 #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
  61 #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
  62 #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
  63
  64 /*
  65  * R16421 (0x4025) - RTC Control
  66  */
  67 #define WM831X_RTC_VALID                        0x8000  /* RTC_VALID */
  68 #define WM831X_RTC_VALID_MASK                   0x8000  /* RTC_VALID */
  69 #define WM831X_RTC_VALID_SHIFT                      15  /* RTC_VALID */
  70 #define WM831X_RTC_VALID_WIDTH                       1  /* RTC_VALID */
  71 #define WM831X_RTC_SYNC_BUSY                    0x4000  /* RTC_SYNC_BUSY */
  72 #define WM831X_RTC_SYNC_BUSY_MASK               0x4000  /* RTC_SYNC_BUSY */
  73 #define WM831X_RTC_SYNC_BUSY_SHIFT                  14  /* RTC_SYNC_BUSY */
  74 #define WM831X_RTC_SYNC_BUSY_WIDTH                   1  /* RTC_SYNC_BUSY */
  75 #define WM831X_RTC_ALM_ENA                      0x0400  /* RTC_ALM_ENA */
  76 #define WM831X_RTC_ALM_ENA_MASK                 0x0400  /* RTC_ALM_ENA */
  77 #define WM831X_RTC_ALM_ENA_SHIFT                    10  /* RTC_ALM_ENA */
  78 #define WM831X_RTC_ALM_ENA_WIDTH                     1  /* RTC_ALM_ENA */
  79 #define WM831X_RTC_PINT_FREQ_MASK               0x0070  /* RTC_PINT_FREQ - [6:4] */
  80 #define WM831X_RTC_PINT_FREQ_SHIFT                   4  /* RTC_PINT_FREQ - [6:4] */
  81 #define WM831X_RTC_PINT_FREQ_WIDTH                   3  /* RTC_PINT_FREQ - [6:4] */
  82
  83 /*
  84  * R16422 (0x4026) - RTC Trim
  85  */
  86 #define WM831X_RTC_TRIM_MASK                    0x03FF  /* RTC_TRIM - [9:0] */
  87 #define WM831X_RTC_TRIM_SHIFT                        0  /* RTC_TRIM - [9:0] */
  88 #define WM831X_RTC_TRIM_WIDTH                       10  /* RTC_TRIM - [9:0] */
  89
  90 #define WM831X_SET_TIME_RETRIES 5
  91 #define WM831X_GET_TIME_RETRIES 5
  92
  93 struct wm831x_rtc {
  94         struct wm831x *wm831x;
  95         struct rtc_device *rtc;
  96         unsigned int alarm_enabled:1;
  97 };
  98
  99 static void wm831x_rtc_add_randomness(struct wm831x *wm831x)
 100 {
 101         int ret;
 102         u16 reg;
 103
 104         /*
 105          * The write counter contains a pseudo-random number which is
 106          * regenerated every time we set the RTC so it should be a
 107          * useful per-system source of entropy.
 108          */
 109         ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER);
 110         if (ret >= 0) {
 111                 reg = ret;
 112                 add_device_randomness(&reg, sizeof(reg));
 113         } else {
 114                 dev_warn(wm831x->dev, "Failed to read RTC write counter: %d\n",
 115                          ret);
 116         }
 117 }
 118
 119 /*
 120  * Read current time and date in RTC
 121  */
 122 static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
 123 {
 124         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 125         struct wm831x *wm831x = wm831x_rtc->wm831x;
 126         u16 time1[2], time2[2];
 127         int ret;
 128         int count = 0;
 129
 130         /* Has the RTC been programmed? */
 131         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 132         if (ret < 0) {
 133                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
 134                 return ret;
 135         }
 136         if (!(ret & WM831X_RTC_VALID)) {
 137                 dev_dbg(dev, "RTC not yet configured\n");
 138                 return -EINVAL;
 139         }
 140
 141         /* Read twice to make sure we don't read a corrupt, partially
 142          * incremented, value.
 143          */
 144         do {
 145                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
 146                                        2, time1);
 147                 if (ret != 0)
 148                         continue;
 149
 150                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
 151                                        2, time2);
 152                 if (ret != 0)
 153                         continue;
 154
 155                 if (memcmp(time1, time2, sizeof(time1)) == 0) {
 156                         u32 time = (time1[0] << 16) | time1[1];
 157
 158                         rtc_time_to_tm(time, tm);
 159                         return 0;
 160                 }
 161
 162         } while (++count < WM831X_GET_TIME_RETRIES);
 163
 164         dev_err(dev, "Timed out reading current time\n");
 165
 166         return -EIO;
 167 }
 168
 169 /*
 170  * Set current time and date in RTC
 171  */
 172 static int wm831x_rtc_set_mmss(struct device *dev, unsigned long time)
 173 {
 174         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 175         struct wm831x *wm831x = wm831x_rtc->wm831x;
 176         struct rtc_time new_tm;
 177         unsigned long new_time;
 178         int ret;
 179         int count = 0;
 180
 181         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
 182                                (time >> 16) & 0xffff);
 183         if (ret < 0) {
 184                 dev_err(dev, "Failed to write TIME_1: %d\n", ret);
 185                 return ret;
 186         }
 187
 188         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
 189         if (ret < 0) {
 190                 dev_err(dev, "Failed to write TIME_2: %d\n", ret);
 191                 return ret;
 192         }
 193
 194         /* Wait for the update to complete - should happen first time
 195          * round but be conservative.
 196          */
 197         do {
 198                 msleep(1);
 199
 200                 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 201                 if (ret < 0)
 202                         ret = WM831X_RTC_SYNC_BUSY;
 203         } while (!(ret & WM831X_RTC_SYNC_BUSY) &&
 204                  ++count < WM831X_SET_TIME_RETRIES);
 205
 206         if (ret & WM831X_RTC_SYNC_BUSY) {
 207                 dev_err(dev, "Timed out writing RTC update\n");
 208                 return -EIO;
 209         }
 210
 211         /* Check that the update was accepted; security features may
 212          * have caused the update to be ignored.
 213          */
 214         ret = wm831x_rtc_readtime(dev, &new_tm);
 215         if (ret < 0)
 216                 return ret;
 217
 218         ret = rtc_tm_to_time(&new_tm, &new_time);
 219         if (ret < 0) {
 220                 dev_err(dev, "Failed to convert time: %d\n", ret);
 221                 return ret;
 222         }
 223
 224         /* Allow a second of change in case of tick */
 225         if (new_time - time > 1) {
 226                 dev_err(dev, "RTC update not permitted by hardware\n");
 227                 return -EPERM;
 228         }
 229
 230         return 0;
 231 }
 232
 233 /*
 234  * Read alarm time and date in RTC
 235  */
 236 static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 237 {
 238         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 239         int ret;
 240         u16 data[2];
 241         u32 time;
 242
 243         ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
 244                                2, data);
 245         if (ret != 0) {
 246                 dev_err(dev, "Failed to read alarm time: %d\n", ret);
 247                 return ret;
 248         }
 249
 250         time = (data[0] << 16) | data[1];
 251
 252         rtc_time_to_tm(time, &alrm->time);
 253
 254         ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
 255         if (ret < 0) {
 256                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
 257                 return ret;
 258         }
 259
 260         if (ret & WM831X_RTC_ALM_ENA)
 261                 alrm->enabled = 1;
 262         else
 263                 alrm->enabled = 0;
 264
 265         return 0;
 266 }
 267
 268 static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
 269 {
 270         wm831x_rtc->alarm_enabled = 0;
 271
 272         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 273                                WM831X_RTC_ALM_ENA, 0);
 274 }
 275
 276 static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
 277 {
 278         wm831x_rtc->alarm_enabled = 1;
 279
 280         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 281                                WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
 282 }
 283
 284 static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 285 {
 286         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 287         struct wm831x *wm831x = wm831x_rtc->wm831x;
 288         int ret;
 289         unsigned long time;
 290
 291         ret = rtc_tm_to_time(&alrm->time, &time);
 292         if (ret < 0) {
 293                 dev_err(dev, "Failed to convert time: %d\n", ret);
 294                 return ret;
 295         }
 296
 297         ret = wm831x_rtc_stop_alarm(wm831x_rtc);
 298         if (ret < 0) {
 299                 dev_err(dev, "Failed to stop alarm: %d\n", ret);
 300                 return ret;
 301         }
 302
 303         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
 304                                (time >> 16) & 0xffff);
 305         if (ret < 0) {
 306                 dev_err(dev, "Failed to write ALARM_1: %d\n", ret);
 307                 return ret;
 308         }
 309
 310         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
 311         if (ret < 0) {
 312                 dev_err(dev, "Failed to write ALARM_2: %d\n", ret);
 313                 return ret;
 314         }
 315
 316         if (alrm->enabled) {
 317                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
 318                 if (ret < 0) {
 319                         dev_err(dev, "Failed to start alarm: %d\n", ret);
 320                         return ret;
 321                 }
 322         }
 323
 324         return 0;
 325 }
 326
 327 static int wm831x_rtc_alarm_irq_enable(struct device *dev,
 328                                        unsigned int enabled)
 329 {
 330         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 331
 332         if (enabled)
 333                 return wm831x_rtc_start_alarm(wm831x_rtc);
 334         else
 335                 return wm831x_rtc_stop_alarm(wm831x_rtc);
 336 }
 337
 338 static irqreturn_t wm831x_alm_irq(int irq, void *data)
 339 {
 340         struct wm831x_rtc *wm831x_rtc = data;
 341
 342         rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
 343
 344         return IRQ_HANDLED;
 345 }
 346
 347 static const struct rtc_class_ops wm831x_rtc_ops = {
 348         .read_time = wm831x_rtc_readtime,
 349         .set_mmss = wm831x_rtc_set_mmss,
 350         .read_alarm = wm831x_rtc_readalarm,
 351         .set_alarm = wm831x_rtc_setalarm,
 352         .alarm_irq_enable = wm831x_rtc_alarm_irq_enable,
 353 };
 354
 355 #ifdef CONFIG_PM
 356 /* Turn off the alarm if it should not be a wake source. */
 357 static int wm831x_rtc_suspend(struct device *dev)
 358 {
 359         struct platform_device *pdev = to_platform_device(dev);
 360         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
 361         int ret, enable;
 362
 363         if (wm831x_rtc->alarm_enabled && device_may_wakeup(&pdev->dev))
 364                 enable = WM831X_RTC_ALM_ENA;
 365         else
 366                 enable = 0;
 367
 368         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 369                               WM831X_RTC_ALM_ENA, enable);
 370         if (ret != 0)
 371                 dev_err(&pdev->dev, "Failed to update RTC alarm: %d\n", ret);
 372
 373         return 0;
 374 }
 375
 376 /* Enable the alarm if it should be enabled (in case it was disabled to
 377  * prevent use as a wake source).
 378  */
 379 static int wm831x_rtc_resume(struct device *dev)
 380 {
 381         struct platform_device *pdev = to_platform_device(dev);
 382         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
 383         int ret;
 384
 385         if (wm831x_rtc->alarm_enabled) {
 386                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
 387                 if (ret != 0)
 388                         dev_err(&pdev->dev,
 389                                 "Failed to restart RTC alarm: %d\n", ret);
 390         }
 391
 392         return 0;
 393 }
 394
 395 /* Unconditionally disable the alarm */
 396 static int wm831x_rtc_freeze(struct device *dev)
 397 {
 398         struct platform_device *pdev = to_platform_device(dev);
 399         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
 400         int ret;
 401
 402         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 403                               WM831X_RTC_ALM_ENA, 0);
 404         if (ret != 0)
 405                 dev_err(&pdev->dev, "Failed to stop RTC alarm: %d\n", ret);
 406
 407         return 0;
 408 }
 409 #else
 410 #define wm831x_rtc_suspend NULL
 411 #define wm831x_rtc_resume NULL
 412 #define wm831x_rtc_freeze NULL
 413 #endif
 414
 415 static int wm831x_rtc_probe(struct platform_device *pdev)
 416 {
 417         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 418         struct wm831x_rtc *wm831x_rtc;
 419         int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM"));
 420         int ret = 0;
 421
 422         wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL);
 423         if (wm831x_rtc == NULL)
 424                 return -ENOMEM;
 425
 426         platform_set_drvdata(pdev, wm831x_rtc);
 427         wm831x_rtc->wm831x = wm831x;
 428
 429         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 430         if (ret < 0) {
 431                 dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret);
 432                 goto err;
 433         }
 434         if (ret & WM831X_RTC_ALM_ENA)
 435                 wm831x_rtc->alarm_enabled = 1;
 436
 437         device_init_wakeup(&pdev->dev, 1);
 438
 439         wm831x_rtc->rtc = devm_rtc_device_register(&pdev->dev, "wm831x",
 440                                               &wm831x_rtc_ops, THIS_MODULE);
 441         if (IS_ERR(wm831x_rtc->rtc)) {
 442                 ret = PTR_ERR(wm831x_rtc->rtc);
 443                 goto err;
 444         }
 445
 446         ret = devm_request_threaded_irq(&pdev->dev, alm_irq, NULL,
 447                                 wm831x_alm_irq,
 448                                 IRQF_TRIGGER_RISING, "RTC alarm",
 449                                 wm831x_rtc);
 450         if (ret != 0) {
 451                 dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
 452                         alm_irq, ret);
 453         }
 454
 455         wm831x_rtc_add_randomness(wm831x);
 456
 457         return 0;
 458
 459 err:
 460         return ret;
 461 }
 462
 463 static const struct dev_pm_ops wm831x_rtc_pm_ops = {
 464         .suspend = wm831x_rtc_suspend,
 465         .resume = wm831x_rtc_resume,
 466
 467         .freeze = wm831x_rtc_freeze,
 468         .thaw = wm831x_rtc_resume,
 469         .restore = wm831x_rtc_resume,
 470
 471         .poweroff = wm831x_rtc_suspend,
 472 };
 473
 474 static struct platform_driver wm831x_rtc_driver = {
 475         .probe = wm831x_rtc_probe,
 476         .driver = {
 477                 .name = "wm831x-rtc",
 478                 .pm = &wm831x_rtc_pm_ops,
 479         },
 480 };
 481
 482 module_platform_driver(wm831x_rtc_driver);
 483
 484 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
 485 MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
 486 MODULE_LICENSE("GPL");
 487 MODULE_ALIAS("platform:wm831x-rtc");