drivers/rtc/rtc-wm831x.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      Real Time Clock driver for Wolfson Microelectronics WM831x
   4  *
   5  *      Copyright (C) 2009 Wolfson Microelectronics PLC.
   6  *
   7  *  Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
   8  *
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/time.h>
  14 #include <linux/rtc.h>
  15 #include <linux/slab.h>
  16 #include <linux/bcd.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/ioctl.h>
  19 #include <linux/completion.h>
  20 #include <linux/mfd/wm831x/core.h>
  21 #include <linux/delay.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/random.h>
  24
  25 /*
  26  * R16416 (0x4020) - RTC Write Counter
  27  */
  28 #define WM831X_RTC_WR_CNT_MASK                  0xFFFF  /* RTC_WR_CNT - [15:0] */
  29 #define WM831X_RTC_WR_CNT_SHIFT                      0  /* RTC_WR_CNT - [15:0] */
  30 #define WM831X_RTC_WR_CNT_WIDTH                     16  /* RTC_WR_CNT - [15:0] */
  31
  32 /*
  33  * R16417 (0x4021) - RTC Time 1
  34  */
  35 #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
  36 #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
  37 #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
  38
  39 /*
  40  * R16418 (0x4022) - RTC Time 2
  41  */
  42 #define WM831X_RTC_TIME_MASK                    0xFFFF  /* RTC_TIME - [15:0] */
  43 #define WM831X_RTC_TIME_SHIFT                        0  /* RTC_TIME - [15:0] */
  44 #define WM831X_RTC_TIME_WIDTH                       16  /* RTC_TIME - [15:0] */
  45
  46 /*
  47  * R16419 (0x4023) - RTC Alarm 1
  48  */
  49 #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
  50 #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
  51 #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
  52
  53 /*
  54  * R16420 (0x4024) - RTC Alarm 2
  55  */
  56 #define WM831X_RTC_ALM_MASK                     0xFFFF  /* RTC_ALM - [15:0] */
  57 #define WM831X_RTC_ALM_SHIFT                         0  /* RTC_ALM - [15:0] */
  58 #define WM831X_RTC_ALM_WIDTH                        16  /* RTC_ALM - [15:0] */
  59
  60 /*
  61  * R16421 (0x4025) - RTC Control
  62  */
  63 #define WM831X_RTC_VALID                        0x8000  /* RTC_VALID */
  64 #define WM831X_RTC_VALID_MASK                   0x8000  /* RTC_VALID */
  65 #define WM831X_RTC_VALID_SHIFT                      15  /* RTC_VALID */
  66 #define WM831X_RTC_VALID_WIDTH                       1  /* RTC_VALID */
  67 #define WM831X_RTC_SYNC_BUSY                    0x4000  /* RTC_SYNC_BUSY */
  68 #define WM831X_RTC_SYNC_BUSY_MASK               0x4000  /* RTC_SYNC_BUSY */
  69 #define WM831X_RTC_SYNC_BUSY_SHIFT                  14  /* RTC_SYNC_BUSY */
  70 #define WM831X_RTC_SYNC_BUSY_WIDTH                   1  /* RTC_SYNC_BUSY */
  71 #define WM831X_RTC_ALM_ENA                      0x0400  /* RTC_ALM_ENA */
  72 #define WM831X_RTC_ALM_ENA_MASK                 0x0400  /* RTC_ALM_ENA */
  73 #define WM831X_RTC_ALM_ENA_SHIFT                    10  /* RTC_ALM_ENA */
  74 #define WM831X_RTC_ALM_ENA_WIDTH                     1  /* RTC_ALM_ENA */
  75 #define WM831X_RTC_PINT_FREQ_MASK               0x0070  /* RTC_PINT_FREQ - [6:4] */
  76 #define WM831X_RTC_PINT_FREQ_SHIFT                   4  /* RTC_PINT_FREQ - [6:4] */
  77 #define WM831X_RTC_PINT_FREQ_WIDTH                   3  /* RTC_PINT_FREQ - [6:4] */
  78
  79 /*
  80  * R16422 (0x4026) - RTC Trim
  81  */
  82 #define WM831X_RTC_TRIM_MASK                    0x03FF  /* RTC_TRIM - [9:0] */
  83 #define WM831X_RTC_TRIM_SHIFT                        0  /* RTC_TRIM - [9:0] */
  84 #define WM831X_RTC_TRIM_WIDTH                       10  /* RTC_TRIM - [9:0] */
  85
  86 #define WM831X_SET_TIME_RETRIES 5
  87 #define WM831X_GET_TIME_RETRIES 5
  88
  89 struct wm831x_rtc {
  90         struct wm831x *wm831x;
  91         struct rtc_device *rtc;
  92         unsigned int alarm_enabled:1;
  93 };
  94
  95 static void wm831x_rtc_add_randomness(struct wm831x *wm831x)
  96 {
  97         int ret;
  98         u16 reg;
  99
 100         /*
 101          * The write counter contains a pseudo-random number which is
 102          * regenerated every time we set the RTC so it should be a
 103          * useful per-system source of entropy.
 104          */
 105         ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER);
 106         if (ret >= 0) {
 107                 reg = ret;
 108                 add_device_randomness(&reg, sizeof(reg));
 109         } else {
 110                 dev_warn(wm831x->dev, "Failed to read RTC write counter: %d\n",
 111                          ret);
 112         }
 113 }
 114
 115 /*
 116  * Read current time and date in RTC
 117  */
 118 static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
 119 {
 120         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 121         struct wm831x *wm831x = wm831x_rtc->wm831x;
 122         u16 time1[2], time2[2];
 123         int ret;
 124         int count = 0;
 125
 126         /* Has the RTC been programmed? */
 127         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 128         if (ret < 0) {
 129                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
 130                 return ret;
 131         }
 132         if (!(ret & WM831X_RTC_VALID)) {
 133                 dev_dbg(dev, "RTC not yet configured\n");
 134                 return -EINVAL;
 135         }
 136
 137         /* Read twice to make sure we don't read a corrupt, partially
 138          * incremented, value.
 139          */
 140         do {
 141                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
 142                                        2, time1);
 143                 if (ret != 0)
 144                         continue;
 145
 146                 ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
 147                                        2, time2);
 148                 if (ret != 0)
 149                         continue;
 150
 151                 if (memcmp(time1, time2, sizeof(time1)) == 0) {
 152                         u32 time = (time1[0] << 16) | time1[1];
 153
 154                         rtc_time64_to_tm(time, tm);
 155                         return 0;
 156                 }
 157
 158         } while (++count < WM831X_GET_TIME_RETRIES);
 159
 160         dev_err(dev, "Timed out reading current time\n");
 161
 162         return -EIO;
 163 }
 164
 165 /*
 166  * Set current time and date in RTC
 167  */
 168 static int wm831x_rtc_settime(struct device *dev, struct rtc_time *tm)
 169 {
 170         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 171         struct wm831x *wm831x = wm831x_rtc->wm831x;
 172         struct rtc_time new_tm;
 173         unsigned long time, new_time;
 174         int ret;
 175         int count = 0;
 176
 177         time = rtc_tm_to_time64(tm);
 178
 179         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
 180                                (time >> 16) & 0xffff);
 181         if (ret < 0) {
 182                 dev_err(dev, "Failed to write TIME_1: %d\n", ret);
 183                 return ret;
 184         }
 185
 186         ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
 187         if (ret < 0) {
 188                 dev_err(dev, "Failed to write TIME_2: %d\n", ret);
 189                 return ret;
 190         }
 191
 192         /* Wait for the update to complete - should happen first time
 193          * round but be conservative.
 194          */
 195         do {
 196                 msleep(1);
 197
 198                 ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 199                 if (ret < 0)
 200                         ret = WM831X_RTC_SYNC_BUSY;
 201         } while (!(ret & WM831X_RTC_SYNC_BUSY) &&
 202                  ++count < WM831X_SET_TIME_RETRIES);
 203
 204         if (ret & WM831X_RTC_SYNC_BUSY) {
 205                 dev_err(dev, "Timed out writing RTC update\n");
 206                 return -EIO;
 207         }
 208
 209         /* Check that the update was accepted; security features may
 210          * have caused the update to be ignored.
 211          */
 212         ret = wm831x_rtc_readtime(dev, &new_tm);
 213         if (ret < 0)
 214                 return ret;
 215
 216         new_time = rtc_tm_to_time64(&new_tm);
 217
 218         /* Allow a second of change in case of tick */
 219         if (new_time - time > 1) {
 220                 dev_err(dev, "RTC update not permitted by hardware\n");
 221                 return -EPERM;
 222         }
 223
 224         return 0;
 225 }
 226
 227 /*
 228  * Read alarm time and date in RTC
 229  */
 230 static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 231 {
 232         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 233         int ret;
 234         u16 data[2];
 235         u32 time;
 236
 237         ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
 238                                2, data);
 239         if (ret != 0) {
 240                 dev_err(dev, "Failed to read alarm time: %d\n", ret);
 241                 return ret;
 242         }
 243
 244         time = (data[0] << 16) | data[1];
 245
 246         rtc_time64_to_tm(time, &alrm->time);
 247
 248         ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
 249         if (ret < 0) {
 250                 dev_err(dev, "Failed to read RTC control: %d\n", ret);
 251                 return ret;
 252         }
 253
 254         if (ret & WM831X_RTC_ALM_ENA)
 255                 alrm->enabled = 1;
 256         else
 257                 alrm->enabled = 0;
 258
 259         return 0;
 260 }
 261
 262 static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
 263 {
 264         wm831x_rtc->alarm_enabled = 0;
 265
 266         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 267                                WM831X_RTC_ALM_ENA, 0);
 268 }
 269
 270 static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
 271 {
 272         wm831x_rtc->alarm_enabled = 1;
 273
 274         return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 275                                WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
 276 }
 277
 278 static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 279 {
 280         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 281         struct wm831x *wm831x = wm831x_rtc->wm831x;
 282         int ret;
 283         unsigned long time;
 284
 285         time = rtc_tm_to_time64(&alrm->time);
 286
 287         ret = wm831x_rtc_stop_alarm(wm831x_rtc);
 288         if (ret < 0) {
 289                 dev_err(dev, "Failed to stop alarm: %d\n", ret);
 290                 return ret;
 291         }
 292
 293         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
 294                                (time >> 16) & 0xffff);
 295         if (ret < 0) {
 296                 dev_err(dev, "Failed to write ALARM_1: %d\n", ret);
 297                 return ret;
 298         }
 299
 300         ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
 301         if (ret < 0) {
 302                 dev_err(dev, "Failed to write ALARM_2: %d\n", ret);
 303                 return ret;
 304         }
 305
 306         if (alrm->enabled) {
 307                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
 308                 if (ret < 0) {
 309                         dev_err(dev, "Failed to start alarm: %d\n", ret);
 310                         return ret;
 311                 }
 312         }
 313
 314         return 0;
 315 }
 316
 317 static int wm831x_rtc_alarm_irq_enable(struct device *dev,
 318                                        unsigned int enabled)
 319 {
 320         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 321
 322         if (enabled)
 323                 return wm831x_rtc_start_alarm(wm831x_rtc);
 324         else
 325                 return wm831x_rtc_stop_alarm(wm831x_rtc);
 326 }
 327
 328 static irqreturn_t wm831x_alm_irq(int irq, void *data)
 329 {
 330         struct wm831x_rtc *wm831x_rtc = data;
 331
 332         rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
 333
 334         return IRQ_HANDLED;
 335 }
 336
 337 static const struct rtc_class_ops wm831x_rtc_ops = {
 338         .read_time = wm831x_rtc_readtime,
 339         .set_time = wm831x_rtc_settime,
 340         .read_alarm = wm831x_rtc_readalarm,
 341         .set_alarm = wm831x_rtc_setalarm,
 342         .alarm_irq_enable = wm831x_rtc_alarm_irq_enable,
 343 };
 344
 345 #ifdef CONFIG_PM
 346 /* Turn off the alarm if it should not be a wake source. */
 347 static int wm831x_rtc_suspend(struct device *dev)
 348 {
 349         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 350         int ret, enable;
 351
 352         if (wm831x_rtc->alarm_enabled && device_may_wakeup(dev))
 353                 enable = WM831X_RTC_ALM_ENA;
 354         else
 355                 enable = 0;
 356
 357         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 358                               WM831X_RTC_ALM_ENA, enable);
 359         if (ret != 0)
 360                 dev_err(dev, "Failed to update RTC alarm: %d\n", ret);
 361
 362         return 0;
 363 }
 364
 365 /* Enable the alarm if it should be enabled (in case it was disabled to
 366  * prevent use as a wake source).
 367  */
 368 static int wm831x_rtc_resume(struct device *dev)
 369 {
 370         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 371         int ret;
 372
 373         if (wm831x_rtc->alarm_enabled) {
 374                 ret = wm831x_rtc_start_alarm(wm831x_rtc);
 375                 if (ret != 0)
 376                         dev_err(dev, "Failed to restart RTC alarm: %d\n", ret);
 377         }
 378
 379         return 0;
 380 }
 381
 382 /* Unconditionally disable the alarm */
 383 static int wm831x_rtc_freeze(struct device *dev)
 384 {
 385         struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
 386         int ret;
 387
 388         ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
 389                               WM831X_RTC_ALM_ENA, 0);
 390         if (ret != 0)
 391                 dev_err(dev, "Failed to stop RTC alarm: %d\n", ret);
 392
 393         return 0;
 394 }
 395 #else
 396 #define wm831x_rtc_suspend NULL
 397 #define wm831x_rtc_resume NULL
 398 #define wm831x_rtc_freeze NULL
 399 #endif
 400
 401 static int wm831x_rtc_probe(struct platform_device *pdev)
 402 {
 403         struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
 404         struct wm831x_rtc *wm831x_rtc;
 405         int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM"));
 406         int ret = 0;
 407
 408         wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL);
 409         if (wm831x_rtc == NULL)
 410                 return -ENOMEM;
 411
 412         platform_set_drvdata(pdev, wm831x_rtc);
 413         wm831x_rtc->wm831x = wm831x;
 414
 415         ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
 416         if (ret < 0) {
 417                 dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret);
 418                 return ret;
 419         }
 420         if (ret & WM831X_RTC_ALM_ENA)
 421                 wm831x_rtc->alarm_enabled = 1;
 422
 423         device_init_wakeup(&pdev->dev, 1);
 424
 425         wm831x_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
 426         if (IS_ERR(wm831x_rtc->rtc))
 427                 return PTR_ERR(wm831x_rtc->rtc);
 428
 429         wm831x_rtc->rtc->ops = &wm831x_rtc_ops;
 430         wm831x_rtc->rtc->range_max = U32_MAX;
 431
 432         ret = rtc_register_device(wm831x_rtc->rtc);
 433         if (ret)
 434                 return ret;
 435
 436         ret = devm_request_threaded_irq(&pdev->dev, alm_irq, NULL,
 437                                 wm831x_alm_irq,
 438                                 IRQF_TRIGGER_RISING, "RTC alarm",
 439                                 wm831x_rtc);
 440         if (ret != 0) {
 441                 dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
 442                         alm_irq, ret);
 443         }
 444
 445         wm831x_rtc_add_randomness(wm831x);
 446
 447         return 0;
 448 }
 449
 450 static const struct dev_pm_ops wm831x_rtc_pm_ops = {
 451         .suspend = wm831x_rtc_suspend,
 452         .resume = wm831x_rtc_resume,
 453
 454         .freeze = wm831x_rtc_freeze,
 455         .thaw = wm831x_rtc_resume,
 456         .restore = wm831x_rtc_resume,
 457
 458         .poweroff = wm831x_rtc_suspend,
 459 };
 460
 461 static struct platform_driver wm831x_rtc_driver = {
 462         .probe = wm831x_rtc_probe,
 463         .driver = {
 464                 .name = "wm831x-rtc",
 465                 .pm = &wm831x_rtc_pm_ops,
 466         },
 467 };
 468
 469 module_platform_driver(wm831x_rtc_driver);
 470
 471 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
 472 MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
 473 MODULE_LICENSE("GPL");
 474 MODULE_ALIAS("platform:wm831x-rtc");