drivers/rtc/rtc-cadence.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Copyright 2019 Cadence
   5  *
   6  * Authors:
   7  *  Jan Kotas <jank@cadence.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/of.h>
  13 #include <linux/io.h>
  14 #include <linux/rtc.h>
  15 #include <linux/clk.h>
  16 #include <linux/bcd.h>
  17 #include <linux/bitfield.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/pm_wakeirq.h>
  20
  21 /* Registers */
  22 #define CDNS_RTC_CTLR           0x00
  23 #define CDNS_RTC_HMR            0x04
  24 #define CDNS_RTC_TIMR           0x08
  25 #define CDNS_RTC_CALR           0x0C
  26 #define CDNS_RTC_TIMAR          0x10
  27 #define CDNS_RTC_CALAR          0x14
  28 #define CDNS_RTC_AENR           0x18
  29 #define CDNS_RTC_EFLR           0x1C
  30 #define CDNS_RTC_IENR           0x20
  31 #define CDNS_RTC_IDISR          0x24
  32 #define CDNS_RTC_IMSKR          0x28
  33 #define CDNS_RTC_STSR           0x2C
  34 #define CDNS_RTC_KRTCR          0x30
  35
  36 /* Control */
  37 #define CDNS_RTC_CTLR_TIME      BIT(0)
  38 #define CDNS_RTC_CTLR_CAL       BIT(1)
  39 #define CDNS_RTC_CTLR_TIME_CAL  (CDNS_RTC_CTLR_TIME | CDNS_RTC_CTLR_CAL)
  40
  41 /* Status */
  42 #define CDNS_RTC_STSR_VT        BIT(0)
  43 #define CDNS_RTC_STSR_VC        BIT(1)
  44 #define CDNS_RTC_STSR_VTA       BIT(2)
  45 #define CDNS_RTC_STSR_VCA       BIT(3)
  46 #define CDNS_RTC_STSR_VT_VC     (CDNS_RTC_STSR_VT | CDNS_RTC_STSR_VC)
  47 #define CDNS_RTC_STSR_VTA_VCA   (CDNS_RTC_STSR_VTA | CDNS_RTC_STSR_VCA)
  48
  49 /* Keep RTC */
  50 #define CDNS_RTC_KRTCR_KRTC     BIT(0)
  51
  52 /* Alarm, Event, Interrupt */
  53 #define CDNS_RTC_AEI_HOS        BIT(0)
  54 #define CDNS_RTC_AEI_SEC        BIT(1)
  55 #define CDNS_RTC_AEI_MIN        BIT(2)
  56 #define CDNS_RTC_AEI_HOUR       BIT(3)
  57 #define CDNS_RTC_AEI_DATE       BIT(4)
  58 #define CDNS_RTC_AEI_MNTH       BIT(5)
  59 #define CDNS_RTC_AEI_ALRM       BIT(6)
  60
  61 /* Time */
  62 #define CDNS_RTC_TIME_H         GENMASK(7, 0)
  63 #define CDNS_RTC_TIME_S         GENMASK(14, 8)
  64 #define CDNS_RTC_TIME_M         GENMASK(22, 16)
  65 #define CDNS_RTC_TIME_HR        GENMASK(29, 24)
  66 #define CDNS_RTC_TIME_PM        BIT(30)
  67 #define CDNS_RTC_TIME_CH        BIT(31)
  68
  69 /* Calendar */
  70 #define CDNS_RTC_CAL_DAY        GENMASK(2, 0)
  71 #define CDNS_RTC_CAL_M          GENMASK(7, 3)
  72 #define CDNS_RTC_CAL_D          GENMASK(13, 8)
  73 #define CDNS_RTC_CAL_Y          GENMASK(23, 16)
  74 #define CDNS_RTC_CAL_C          GENMASK(29, 24)
  75 #define CDNS_RTC_CAL_CH         BIT(31)
  76
  77 #define CDNS_RTC_MAX_REGS_TRIES 3
  78
  79 struct cdns_rtc {
  80         struct rtc_device *rtc_dev;
  81         struct clk *pclk;
  82         struct clk *ref_clk;
  83         void __iomem *regs;
  84         int irq;
  85 };
  86
  87 static void cdns_rtc_set_enabled(struct cdns_rtc *crtc, bool enabled)
  88 {
  89         u32 reg = enabled ? 0x0 : CDNS_RTC_CTLR_TIME_CAL;
  90
  91         writel(reg, crtc->regs + CDNS_RTC_CTLR);
  92 }
  93
  94 static bool cdns_rtc_get_enabled(struct cdns_rtc *crtc)
  95 {
  96         return !(readl(crtc->regs + CDNS_RTC_CTLR) & CDNS_RTC_CTLR_TIME_CAL);
  97 }
  98
  99 static irqreturn_t cdns_rtc_irq_handler(int irq, void *id)
 100 {
 101         struct device *dev = id;
 102         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 103
 104         /* Reading the register clears it */
 105         if (!(readl(crtc->regs + CDNS_RTC_EFLR) & CDNS_RTC_AEI_ALRM))
 106                 return IRQ_NONE;
 107
 108         rtc_update_irq(crtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
 109         return IRQ_HANDLED;
 110 }
 111
 112 static u32 cdns_rtc_time2reg(struct rtc_time *tm)
 113 {
 114         return FIELD_PREP(CDNS_RTC_TIME_S,  bin2bcd(tm->tm_sec))
 115              | FIELD_PREP(CDNS_RTC_TIME_M,  bin2bcd(tm->tm_min))
 116              | FIELD_PREP(CDNS_RTC_TIME_HR, bin2bcd(tm->tm_hour));
 117 }
 118
 119 static void cdns_rtc_reg2time(u32 reg, struct rtc_time *tm)
 120 {
 121         tm->tm_sec  = bcd2bin(FIELD_GET(CDNS_RTC_TIME_S, reg));
 122         tm->tm_min  = bcd2bin(FIELD_GET(CDNS_RTC_TIME_M, reg));
 123         tm->tm_hour = bcd2bin(FIELD_GET(CDNS_RTC_TIME_HR, reg));
 124 }
 125
 126 static int cdns_rtc_read_time(struct device *dev, struct rtc_time *tm)
 127 {
 128         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 129         u32 reg;
 130
 131         /* If the RTC is disabled, assume the values are invalid */
 132         if (!cdns_rtc_get_enabled(crtc))
 133                 return -EINVAL;
 134
 135         cdns_rtc_set_enabled(crtc, false);
 136
 137         reg = readl(crtc->regs + CDNS_RTC_TIMR);
 138         cdns_rtc_reg2time(reg, tm);
 139
 140         reg = readl(crtc->regs + CDNS_RTC_CALR);
 141         tm->tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
 142         tm->tm_mon  = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
 143         tm->tm_year = bcd2bin(FIELD_GET(CDNS_RTC_CAL_Y, reg))
 144                     + bcd2bin(FIELD_GET(CDNS_RTC_CAL_C, reg)) * 100 - 1900;
 145         tm->tm_wday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_DAY, reg)) - 1;
 146
 147         cdns_rtc_set_enabled(crtc, true);
 148         return 0;
 149 }
 150
 151 static int cdns_rtc_set_time(struct device *dev, struct rtc_time *tm)
 152 {
 153         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 154         u32 timr, calr, stsr;
 155         int ret = -EIO;
 156         int year = tm->tm_year + 1900;
 157         int tries;
 158
 159         cdns_rtc_set_enabled(crtc, false);
 160
 161         timr = cdns_rtc_time2reg(tm);
 162
 163         calr = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(tm->tm_mday))
 164              | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(tm->tm_mon + 1))
 165              | FIELD_PREP(CDNS_RTC_CAL_Y, bin2bcd(year % 100))
 166              | FIELD_PREP(CDNS_RTC_CAL_C, bin2bcd(year / 100))
 167              | FIELD_PREP(CDNS_RTC_CAL_DAY, tm->tm_wday + 1);
 168
 169         /* Update registers, check valid flags */
 170         for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
 171                 writel(timr, crtc->regs + CDNS_RTC_TIMR);
 172                 writel(calr, crtc->regs + CDNS_RTC_CALR);
 173                 stsr = readl(crtc->regs + CDNS_RTC_STSR);
 174
 175                 if ((stsr & CDNS_RTC_STSR_VT_VC) == CDNS_RTC_STSR_VT_VC) {
 176                         ret = 0;
 177                         break;
 178                 }
 179         }
 180
 181         cdns_rtc_set_enabled(crtc, true);
 182         return ret;
 183 }
 184
 185 static int cdns_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 186 {
 187         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 188
 189         if (enabled) {
 190                 writel((CDNS_RTC_AEI_SEC | CDNS_RTC_AEI_MIN | CDNS_RTC_AEI_HOUR
 191                         | CDNS_RTC_AEI_DATE | CDNS_RTC_AEI_MNTH),
 192                        crtc->regs + CDNS_RTC_AENR);
 193                 writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IENR);
 194         } else {
 195                 writel(0, crtc->regs + CDNS_RTC_AENR);
 196                 writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IDISR);
 197         }
 198
 199         return 0;
 200 }
 201
 202 static int cdns_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 203 {
 204         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 205         u32 reg;
 206
 207         reg = readl(crtc->regs + CDNS_RTC_TIMAR);
 208         cdns_rtc_reg2time(reg, &alarm->time);
 209
 210         reg = readl(crtc->regs + CDNS_RTC_CALAR);
 211         alarm->time.tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
 212         alarm->time.tm_mon  = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
 213
 214         return 0;
 215 }
 216
 217 static int cdns_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 218 {
 219         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 220         int ret = -EIO;
 221         int tries;
 222         u32 timar, calar, stsr;
 223
 224         cdns_rtc_alarm_irq_enable(dev, 0);
 225
 226         timar = cdns_rtc_time2reg(&alarm->time);
 227         calar = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(alarm->time.tm_mday))
 228               | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(alarm->time.tm_mon + 1));
 229
 230         /* Update registers, check valid alarm flags */
 231         for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
 232                 writel(timar, crtc->regs + CDNS_RTC_TIMAR);
 233                 writel(calar, crtc->regs + CDNS_RTC_CALAR);
 234                 stsr = readl(crtc->regs + CDNS_RTC_STSR);
 235
 236                 if ((stsr & CDNS_RTC_STSR_VTA_VCA) == CDNS_RTC_STSR_VTA_VCA) {
 237                         ret = 0;
 238                         break;
 239                 }
 240         }
 241
 242         if (!ret)
 243                 cdns_rtc_alarm_irq_enable(dev, alarm->enabled);
 244         return ret;
 245 }
 246
 247 static const struct rtc_class_ops cdns_rtc_ops = {
 248         .read_time      = cdns_rtc_read_time,
 249         .set_time       = cdns_rtc_set_time,
 250         .read_alarm     = cdns_rtc_read_alarm,
 251         .set_alarm      = cdns_rtc_set_alarm,
 252         .alarm_irq_enable = cdns_rtc_alarm_irq_enable,
 253 };
 254
 255 static int cdns_rtc_probe(struct platform_device *pdev)
 256 {
 257         struct cdns_rtc *crtc;
 258         int ret;
 259         unsigned long ref_clk_freq;
 260
 261         crtc = devm_kzalloc(&pdev->dev, sizeof(*crtc), GFP_KERNEL);
 262         if (!crtc)
 263                 return -ENOMEM;
 264
 265         crtc->regs = devm_platform_ioremap_resource(pdev, 0);
 266         if (IS_ERR(crtc->regs))
 267                 return PTR_ERR(crtc->regs);
 268
 269         crtc->irq = platform_get_irq(pdev, 0);
 270         if (crtc->irq < 0)
 271                 return -EINVAL;
 272
 273         crtc->pclk = devm_clk_get(&pdev->dev, "pclk");
 274         if (IS_ERR(crtc->pclk)) {
 275                 ret = PTR_ERR(crtc->pclk);
 276                 dev_err(&pdev->dev,
 277                         "Failed to retrieve the peripheral clock, %d\n", ret);
 278                 return ret;
 279         }
 280
 281         crtc->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
 282         if (IS_ERR(crtc->ref_clk)) {
 283                 ret = PTR_ERR(crtc->ref_clk);
 284                 dev_err(&pdev->dev,
 285                         "Failed to retrieve the reference clock, %d\n", ret);
 286                 return ret;
 287         }
 288
 289         crtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
 290         if (IS_ERR(crtc->rtc_dev))
 291                 return PTR_ERR(crtc->rtc_dev);
 292
 293         platform_set_drvdata(pdev, crtc);
 294
 295         ret = clk_prepare_enable(crtc->pclk);
 296         if (ret) {
 297                 dev_err(&pdev->dev,
 298                         "Failed to enable the peripheral clock, %d\n", ret);
 299                 return ret;
 300         }
 301
 302         ret = clk_prepare_enable(crtc->ref_clk);
 303         if (ret) {
 304                 dev_err(&pdev->dev,
 305                         "Failed to enable the reference clock, %d\n", ret);
 306                 goto err_disable_pclk;
 307         }
 308
 309         ref_clk_freq = clk_get_rate(crtc->ref_clk);
 310         if ((ref_clk_freq != 1) && (ref_clk_freq != 100)) {
 311                 dev_err(&pdev->dev,
 312                         "Invalid reference clock frequency %lu Hz.\n",
 313                         ref_clk_freq);
 314                 ret = -EINVAL;
 315                 goto err_disable_ref_clk;
 316         }
 317
 318         ret = devm_request_irq(&pdev->dev, crtc->irq,
 319                                cdns_rtc_irq_handler, 0,
 320                                dev_name(&pdev->dev), &pdev->dev);
 321         if (ret) {
 322                 dev_err(&pdev->dev,
 323                         "Failed to request interrupt for the device, %d\n",
 324                         ret);
 325                 goto err_disable_ref_clk;
 326         }
 327
 328         /* The RTC supports 01.01.1900 - 31.12.2999 */
 329         crtc->rtc_dev->range_min = mktime64(1900,  1,  1,  0,  0,  0);
 330         crtc->rtc_dev->range_max = mktime64(2999, 12, 31, 23, 59, 59);
 331
 332         crtc->rtc_dev->ops = &cdns_rtc_ops;
 333         device_init_wakeup(&pdev->dev, true);
 334
 335         /* Always use 24-hour mode and keep the RTC values */
 336         writel(0, crtc->regs + CDNS_RTC_HMR);
 337         writel(CDNS_RTC_KRTCR_KRTC, crtc->regs + CDNS_RTC_KRTCR);
 338
 339         ret = devm_rtc_register_device(crtc->rtc_dev);
 340         if (ret)
 341                 goto err_disable_wakeup;
 342
 343         return 0;
 344
 345 err_disable_wakeup:
 346         device_init_wakeup(&pdev->dev, false);
 347
 348 err_disable_ref_clk:
 349         clk_disable_unprepare(crtc->ref_clk);
 350
 351 err_disable_pclk:
 352         clk_disable_unprepare(crtc->pclk);
 353
 354         return ret;
 355 }
 356
 357 static int cdns_rtc_remove(struct platform_device *pdev)
 358 {
 359         struct cdns_rtc *crtc = platform_get_drvdata(pdev);
 360
 361         cdns_rtc_alarm_irq_enable(&pdev->dev, 0);
 362         device_init_wakeup(&pdev->dev, 0);
 363
 364         clk_disable_unprepare(crtc->pclk);
 365         clk_disable_unprepare(crtc->ref_clk);
 366
 367         return 0;
 368 }
 369
 370 #ifdef CONFIG_PM_SLEEP
 371 static int cdns_rtc_suspend(struct device *dev)
 372 {
 373         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 374
 375         if (device_may_wakeup(dev))
 376                 enable_irq_wake(crtc->irq);
 377
 378         return 0;
 379 }
 380
 381 static int cdns_rtc_resume(struct device *dev)
 382 {
 383         struct cdns_rtc *crtc = dev_get_drvdata(dev);
 384
 385         if (device_may_wakeup(dev))
 386                 disable_irq_wake(crtc->irq);
 387
 388         return 0;
 389 }
 390 #endif
 391
 392 static SIMPLE_DEV_PM_OPS(cdns_rtc_pm_ops, cdns_rtc_suspend, cdns_rtc_resume);
 393
 394 static const struct of_device_id cdns_rtc_of_match[] = {
 395         { .compatible = "cdns,rtc-r109v3" },
 396         { },
 397 };
 398 MODULE_DEVICE_TABLE(of, cdns_rtc_of_match);
 399
 400 static struct platform_driver cdns_rtc_driver = {
 401         .driver = {
 402                 .name = "cdns-rtc",
 403                 .of_match_table = cdns_rtc_of_match,
 404                 .pm = &cdns_rtc_pm_ops,
 405         },
 406         .probe = cdns_rtc_probe,
 407         .remove = cdns_rtc_remove,
 408 };
 409 module_platform_driver(cdns_rtc_driver);
 410
 411 MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
 412 MODULE_DESCRIPTION("Cadence RTC driver");
 413 MODULE_LICENSE("GPL v2");
 414 MODULE_ALIAS("platform:cdns-rtc");