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
  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 /*
 100  * Read current time and date in RTC
 101  */
 102 static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
 103 {
 104         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 105         struct wm831x *wm831x = wm831x_rtc->wm831x;
 106         u16 time1[2], time2[2];
 107         int ret;
 108         int count = 0;
 109
 110         /* Has the RTC been programmed? */
 111         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 112         if (ret < 0) {
 113                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
 114                 return ret;
 115         }
 116         if (!(ret & WM831X_RTC_VALID)) {
 117                 dev_dbg(dev, "RTC not yet configured\n");
 118                 return -EINVAL;
 119         }
 120
 121         /* Read twice to make sure we don't read a corrupt, partially
 122          * incremented, value.
 123          */
 124         do {
 125                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
 126                                        2, time1);
 127                 if (ret != 0)
 128                         continue;
 129
 130                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
 131                                        2, time2);
 132                 if (ret != 0)
 133                         continue;
 134
 135                 if (memcmp(time1, time2, sizeof(time1)) == 0) {
 136                         u32 time = (time1[0] << 16) | time1[1];
 137
 138                         rtc_time_to_tm(time, tm);
 139                         return rtc_valid_tm(tm);
 140                 }
 141
 142         } while (++count < WM831X_GET_TIME_RETRIES);
 143
 144         dev_err(dev, "Timed out reading current time\n");
 145
 146         return -EIO;
 147 }
 148
 149 /*
 150  * Set current time and date in RTC
 151  */
 152 static int wm831x_rtc_set_mmss(struct device *dev, unsigned long time)
 153 {
 154         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 155         struct wm831x *wm831x = wm831x_rtc->wm831x;
 156         struct rtc_time new_tm;
 157         unsigned long new_time;
 158         int ret;
 159         int count = 0;
 160
 161         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
 162                                (time >> 16) & 0xffff);
 163         if (ret < 0) {
 164                 dev_err(dev, "Failed to write TIME_1: %d\n", ret);
 165                 return ret;
 166         }
 167
 168         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
 169         if (ret < 0) {
 170                 dev_err(dev, "Failed to write TIME_2: %d\n", ret);
 171                 return ret;
 172         }
 173
 174         /* Wait for the update to complete - should happen first time
 175          * round but be conservative.
 176          */
 177         do {
 178                 msleep(1);
 179
 180                 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 181                 if (ret < 0)
 182                         ret = WM831X_RTC_SYNC_BUSY;
 183         } while (!(ret & WM831X_RTC_SYNC_BUSY) &&
 184                  ++count < WM831X_SET_TIME_RETRIES);
 185
 186         if (ret & WM831X_RTC_SYNC_BUSY) {
 187                 dev_err(dev, "Timed out writing RTC update\n");
 188                 return -EIO;
 189         }
 190
 191         /* Check that the update was accepted; security features may
 192          * have caused the update to be ignored.
 193          */
 194         ret = wm831x_rtc_readtime(dev, &new_tm);
 195         if (ret < 0)
 196                 return ret;
 197
 198         ret = rtc_tm_to_time(&new_tm, &new_time);
 199         if (ret < 0) {
 200                 dev_err(dev, "Failed to convert time: %d\n", ret);
 201                 return ret;
 202         }
 203
 204         /* Allow a second of change in case of tick */
 205         if (new_time - time > 1) {
 206                 dev_err(dev, "RTC update not permitted by hardware\n");
 207                 return -EPERM;
 208         }
 209
 210         return 0;
 211 }
 212
 213 /*
 214  * Read alarm time and date in RTC
 215  */
 216 static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 217 {
 218         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 219         int ret;
 220         u16 data[2];
 221         u32 time;
 222
 223         ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
 224                                2, data);
 225         if (ret != 0) {
 226                 dev_err(dev, "Failed to read alarm time: %d\n", ret);
 227                 return ret;
 228         }
 229
 230         time = (data[0] << 16) | data[1];
 231
 232         rtc_time_to_tm(time, &alrm->time);
 233
 234         ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
 235         if (ret < 0) {
 236                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
 237                 return ret;
 238         }
 239
 240         if (ret & WM831X_RTC_ALM_ENA)
 241                 alrm->enabled = 1;
 242         else
 243                 alrm->enabled = 0;
 244
 245         return 0;
 246 }
 247
 248 static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
 249 {
 250         wm831x_rtc->alarm_enabled = 0;
 251
 252         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 253                                WM831X_RTC_ALM_ENA, 0);
 254 }
 255
 256 static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
 257 {
 258         wm831x_rtc->alarm_enabled = 1;
 259
 260         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 261                                WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
 262 }
 263
 264 static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 265 {
 266         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 267         struct wm831x *wm831x = wm831x_rtc->wm831x;
 268         int ret;
 269         unsigned long time;
 270
 271         ret = rtc_tm_to_time(&alrm->time, &time);
 272         if (ret < 0) {
 273                 dev_err(dev, "Failed to convert time: %d\n", ret);
 274                 return ret;
 275         }
 276
 277         ret = wm831x_rtc_stop_alarm(wm831x_rtc);
 278         if (ret < 0) {
 279                 dev_err(dev, "Failed to stop alarm: %d\n", ret);
 280                 return ret;
 281         }
 282
 283         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
 284                                (time >> 16) & 0xffff);
 285         if (ret < 0) {
 286                 dev_err(dev, "Failed to write ALARM_1: %d\n", ret);
 287                 return ret;
 288         }
 289
 290         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
 291         if (ret < 0) {
 292                 dev_err(dev, "Failed to write ALARM_2: %d\n", ret);
 293                 return ret;
 294         }
 295
 296         if (alrm->enabled) {
 297                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
 298                 if (ret < 0) {
 299                         dev_err(dev, "Failed to start alarm: %d\n", ret);
 300                         return ret;
 301                 }
 302         }
 303
 304         return 0;
 305 }
 306
 307 static int wm831x_rtc_alarm_irq_enable(struct device *dev,
 308                                        unsigned int enabled)
 309 {
 310         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 311
 312         if (enabled)
 313                 return wm831x_rtc_start_alarm(wm831x_rtc);
 314         else
 315                 return wm831x_rtc_stop_alarm(wm831x_rtc);
 316 }
 317
 318 static irqreturn_t wm831x_alm_irq(int irq, void *data)
 319 {
 320         struct wm831x_rtc *wm831x_rtc = data;
 321
 322         rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
 323
 324         return IRQ_HANDLED;
 325 }
 326
 327 static const struct rtc_class_ops wm831x_rtc_ops = {
 328         .read_time = wm831x_rtc_readtime,
 329         .set_mmss = wm831x_rtc_set_mmss,
 330         .read_alarm = wm831x_rtc_readalarm,
 331         .set_alarm = wm831x_rtc_setalarm,
 332         .alarm_irq_enable = wm831x_rtc_alarm_irq_enable,
 333 };
 334
 335 #ifdef CONFIG_PM
 336 /* Turn off the alarm if it should not be a wake source. */
 337 static int wm831x_rtc_suspend(struct device *dev)
 338 {
 339         struct platform_device *pdev = to_platform_device(dev);
 340         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
 341         int ret, enable;
 342
 343         if (wm831x_rtc->alarm_enabled && device_may_wakeup(&pdev->dev))
 344                 enable = WM831X_RTC_ALM_ENA;
 345         else
 346                 enable = 0;
 347
 348         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 349                               WM831X_RTC_ALM_ENA, enable);
 350         if (ret != 0)
 351                 dev_err(&pdev->dev, "Failed to update RTC alarm: %d\n", ret);
 352
 353         return 0;
 354 }
 355
 356 /* Enable the alarm if it should be enabled (in case it was disabled to
 357  * prevent use as a wake source).
 358  */
 359 static int wm831x_rtc_resume(struct device *dev)
 360 {
 361         struct platform_device *pdev = to_platform_device(dev);
 362         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
 363         int ret;
 364
 365         if (wm831x_rtc->alarm_enabled) {
 366                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
 367                 if (ret != 0)
 368                         dev_err(&pdev->dev,
 369                                 "Failed to restart RTC alarm: %d\n", ret);
 370         }
 371
 372         return 0;
 373 }
 374
 375 /* Unconditionally disable the alarm */
 376 static int wm831x_rtc_freeze(struct device *dev)
 377 {
 378         struct platform_device *pdev = to_platform_device(dev);
 379         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(&pdev->dev);
 380         int ret;
 381
 382         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 383                               WM831X_RTC_ALM_ENA, 0);
 384         if (ret != 0)
 385                 dev_err(&pdev->dev, "Failed to stop RTC alarm: %d\n", ret);
 386
 387         return 0;
 388 }
 389 #else
 390 #define wm831x_rtc_suspend NULL
 391 #define wm831x_rtc_resume NULL
 392 #define wm831x_rtc_freeze NULL
 393 #endif
 394
 395 static int wm831x_rtc_probe(struct platform_device *pdev)
 396 {
 397         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 398         struct wm831x_rtc *wm831x_rtc;
 399         int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM"));
 400         int ret = 0;
 401
 402         wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL);
 403         if (wm831x_rtc == NULL)
 404                 return -ENOMEM;
 405
 406         platform_set_drvdata(pdev, wm831x_rtc);
 407         wm831x_rtc->wm831x = wm831x;
 408
 409         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 410         if (ret < 0) {
 411                 dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret);
 412                 goto err;
 413         }
 414         if (ret & WM831X_RTC_ALM_ENA)
 415                 wm831x_rtc->alarm_enabled = 1;
 416
 417         device_init_wakeup(&pdev->dev, 1);
 418
 419         wm831x_rtc->rtc = rtc_device_register("wm831x", &pdev->dev,
 420                                               &wm831x_rtc_ops, THIS_MODULE);
 421         if (IS_ERR(wm831x_rtc->rtc)) {
 422                 ret = PTR_ERR(wm831x_rtc->rtc);
 423                 goto err;
 424         }
 425
 426         ret = request_threaded_irq(alm_irq, NULL, wm831x_alm_irq,
 427                                    IRQF_TRIGGER_RISING, "RTC alarm",
 428                                    wm831x_rtc);
 429         if (ret != 0) {
 430                 dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
 431                         alm_irq, ret);
 432         }
 433
 434         return 0;
 435
 436 err:
 437         return ret;
 438 }
 439
 440 static int __devexit wm831x_rtc_remove(struct platform_device *pdev)
 441 {
 442         struct wm831x_rtc *wm831x_rtc = platform_get_drvdata(pdev);
 443         int alm_irq = platform_get_irq_byname(pdev, "ALM");
 444
 445         free_irq(alm_irq, wm831x_rtc);
 446         rtc_device_unregister(wm831x_rtc->rtc);
 447
 448         return 0;
 449 }
 450
 451 static const struct dev_pm_ops wm831x_rtc_pm_ops = {
 452         .suspend = wm831x_rtc_suspend,
 453         .resume = wm831x_rtc_resume,
 454
 455         .freeze = wm831x_rtc_freeze,
 456         .thaw = wm831x_rtc_resume,
 457         .restore = wm831x_rtc_resume,
 458
 459         .poweroff = wm831x_rtc_suspend,
 460 };
 461
 462 static struct platform_driver wm831x_rtc_driver = {
 463         .probe = wm831x_rtc_probe,
 464         .remove = __devexit_p(wm831x_rtc_remove),
 465         .driver = {
 466                 .name = "wm831x-rtc",
 467                 .pm = &wm831x_rtc_pm_ops,
 468         },
 469 };
 470
 471 module_platform_driver(wm831x_rtc_driver);
 472
 473 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
 474 MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
 475 MODULE_LICENSE("GPL");
 476 MODULE_ALIAS("platform:wm831x-rtc");