drivers/rtc/rtc-stm32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STMicroelectronics 2017
   4  * Author:  Amelie Delaunay <amelie.delaunay@st.com>
   5  */
   6
   7 #include <linux/bcd.h>
   8 #include <linux/clk.h>
   9 #include <linux/iopoll.h>
  10 #include <linux/ioport.h>
  11 #include <linux/mfd/syscon.h>
  12 #include <linux/module.h>
  13 #include <linux/of_device.h>
  14 #include <linux/pm_wakeirq.h>
  15 #include <linux/regmap.h>
  16 #include <linux/rtc.h>
  17
  18 #define DRIVER_NAME "stm32_rtc"
  19
  20 /* STM32_RTC_TR bit fields  */
  21 #define STM32_RTC_TR_SEC_SHIFT          0
  22 #define STM32_RTC_TR_SEC                GENMASK(6, 0)
  23 #define STM32_RTC_TR_MIN_SHIFT          8
  24 #define STM32_RTC_TR_MIN                GENMASK(14, 8)
  25 #define STM32_RTC_TR_HOUR_SHIFT         16
  26 #define STM32_RTC_TR_HOUR               GENMASK(21, 16)
  27
  28 /* STM32_RTC_DR bit fields */
  29 #define STM32_RTC_DR_DATE_SHIFT         0
  30 #define STM32_RTC_DR_DATE               GENMASK(5, 0)
  31 #define STM32_RTC_DR_MONTH_SHIFT        8
  32 #define STM32_RTC_DR_MONTH              GENMASK(12, 8)
  33 #define STM32_RTC_DR_WDAY_SHIFT         13
  34 #define STM32_RTC_DR_WDAY               GENMASK(15, 13)
  35 #define STM32_RTC_DR_YEAR_SHIFT         16
  36 #define STM32_RTC_DR_YEAR               GENMASK(23, 16)
  37
  38 /* STM32_RTC_CR bit fields */
  39 #define STM32_RTC_CR_FMT                BIT(6)
  40 #define STM32_RTC_CR_ALRAE              BIT(8)
  41 #define STM32_RTC_CR_ALRAIE             BIT(12)
  42
  43 /* STM32_RTC_ISR/STM32_RTC_ICSR bit fields */
  44 #define STM32_RTC_ISR_ALRAWF            BIT(0)
  45 #define STM32_RTC_ISR_INITS             BIT(4)
  46 #define STM32_RTC_ISR_RSF               BIT(5)
  47 #define STM32_RTC_ISR_INITF             BIT(6)
  48 #define STM32_RTC_ISR_INIT              BIT(7)
  49 #define STM32_RTC_ISR_ALRAF             BIT(8)
  50
  51 /* STM32_RTC_PRER bit fields */
  52 #define STM32_RTC_PRER_PRED_S_SHIFT     0
  53 #define STM32_RTC_PRER_PRED_S           GENMASK(14, 0)
  54 #define STM32_RTC_PRER_PRED_A_SHIFT     16
  55 #define STM32_RTC_PRER_PRED_A           GENMASK(22, 16)
  56
  57 /* STM32_RTC_ALRMAR and STM32_RTC_ALRMBR bit fields */
  58 #define STM32_RTC_ALRMXR_SEC_SHIFT      0
  59 #define STM32_RTC_ALRMXR_SEC            GENMASK(6, 0)
  60 #define STM32_RTC_ALRMXR_SEC_MASK       BIT(7)
  61 #define STM32_RTC_ALRMXR_MIN_SHIFT      8
  62 #define STM32_RTC_ALRMXR_MIN            GENMASK(14, 8)
  63 #define STM32_RTC_ALRMXR_MIN_MASK       BIT(15)
  64 #define STM32_RTC_ALRMXR_HOUR_SHIFT     16
  65 #define STM32_RTC_ALRMXR_HOUR           GENMASK(21, 16)
  66 #define STM32_RTC_ALRMXR_PM             BIT(22)
  67 #define STM32_RTC_ALRMXR_HOUR_MASK      BIT(23)
  68 #define STM32_RTC_ALRMXR_DATE_SHIFT     24
  69 #define STM32_RTC_ALRMXR_DATE           GENMASK(29, 24)
  70 #define STM32_RTC_ALRMXR_WDSEL          BIT(30)
  71 #define STM32_RTC_ALRMXR_WDAY_SHIFT     24
  72 #define STM32_RTC_ALRMXR_WDAY           GENMASK(27, 24)
  73 #define STM32_RTC_ALRMXR_DATE_MASK      BIT(31)
  74
  75 /* STM32_RTC_SR/_SCR bit fields */
  76 #define STM32_RTC_SR_ALRA               BIT(0)
  77
  78 /* STM32_RTC_VERR bit fields */
  79 #define STM32_RTC_VERR_MINREV_SHIFT     0
  80 #define STM32_RTC_VERR_MINREV           GENMASK(3, 0)
  81 #define STM32_RTC_VERR_MAJREV_SHIFT     4
  82 #define STM32_RTC_VERR_MAJREV           GENMASK(7, 4)
  83
  84 /* STM32_RTC_WPR key constants */
  85 #define RTC_WPR_1ST_KEY                 0xCA
  86 #define RTC_WPR_2ND_KEY                 0x53
  87 #define RTC_WPR_WRONG_KEY               0xFF
  88
  89 /* Max STM32 RTC register offset is 0x3FC */
  90 #define UNDEF_REG                       0xFFFF
  91
  92 struct stm32_rtc;
  93
  94 struct stm32_rtc_registers {
  95         u16 tr;
  96         u16 dr;
  97         u16 cr;
  98         u16 isr;
  99         u16 prer;
 100         u16 alrmar;
 101         u16 wpr;
 102         u16 sr;
 103         u16 scr;
 104         u16 verr;
 105 };
 106
 107 struct stm32_rtc_events {
 108         u32 alra;
 109 };
 110
 111 struct stm32_rtc_data {
 112         const struct stm32_rtc_registers regs;
 113         const struct stm32_rtc_events events;
 114         void (*clear_events)(struct stm32_rtc *rtc, unsigned int flags);
 115         bool has_pclk;
 116         bool need_dbp;
 117         bool has_wakeirq;
 118 };
 119
 120 struct stm32_rtc {
 121         struct rtc_device *rtc_dev;
 122         void __iomem *base;
 123         struct regmap *dbp;
 124         unsigned int dbp_reg;
 125         unsigned int dbp_mask;
 126         struct clk *pclk;
 127         struct clk *rtc_ck;
 128         const struct stm32_rtc_data *data;
 129         int irq_alarm;
 130         int wakeirq_alarm;
 131 };
 132
 133 static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
 134 {
 135         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 136
 137         writel_relaxed(RTC_WPR_1ST_KEY, rtc->base + regs->wpr);
 138         writel_relaxed(RTC_WPR_2ND_KEY, rtc->base + regs->wpr);
 139 }
 140
 141 static void stm32_rtc_wpr_lock(struct stm32_rtc *rtc)
 142 {
 143         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 144
 145         writel_relaxed(RTC_WPR_WRONG_KEY, rtc->base + regs->wpr);
 146 }
 147
 148 static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
 149 {
 150         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 151         unsigned int isr = readl_relaxed(rtc->base + regs->isr);
 152
 153         if (!(isr & STM32_RTC_ISR_INITF)) {
 154                 isr |= STM32_RTC_ISR_INIT;
 155                 writel_relaxed(isr, rtc->base + regs->isr);
 156
 157                 /*
 158                  * It takes around 2 rtc_ck clock cycles to enter in
 159                  * initialization phase mode (and have INITF flag set). As
 160                  * slowest rtc_ck frequency may be 32kHz and highest should be
 161                  * 1MHz, we poll every 10 us with a timeout of 100ms.
 162                  */
 163                 return readl_relaxed_poll_timeout_atomic(
 164                                         rtc->base + regs->isr,
 165                                         isr, (isr & STM32_RTC_ISR_INITF),
 166                                         10, 100000);
 167         }
 168
 169         return 0;
 170 }
 171
 172 static void stm32_rtc_exit_init_mode(struct stm32_rtc *rtc)
 173 {
 174         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 175         unsigned int isr = readl_relaxed(rtc->base + regs->isr);
 176
 177         isr &= ~STM32_RTC_ISR_INIT;
 178         writel_relaxed(isr, rtc->base + regs->isr);
 179 }
 180
 181 static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)
 182 {
 183         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 184         unsigned int isr = readl_relaxed(rtc->base + regs->isr);
 185
 186         isr &= ~STM32_RTC_ISR_RSF;
 187         writel_relaxed(isr, rtc->base + regs->isr);
 188
 189         /*
 190          * Wait for RSF to be set to ensure the calendar registers are
 191          * synchronised, it takes around 2 rtc_ck clock cycles
 192          */
 193         return readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
 194                                                  isr,
 195                                                  (isr & STM32_RTC_ISR_RSF),
 196                                                  10, 100000);
 197 }
 198
 199 static void stm32_rtc_clear_event_flags(struct stm32_rtc *rtc,
 200                                         unsigned int flags)
 201 {
 202         rtc->data->clear_events(rtc, flags);
 203 }
 204
 205 static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
 206 {
 207         struct stm32_rtc *rtc = (struct stm32_rtc *)dev_id;
 208         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 209         const struct stm32_rtc_events *evts = &rtc->data->events;
 210         unsigned int status, cr;
 211
 212         mutex_lock(&rtc->rtc_dev->ops_lock);
 213
 214         status = readl_relaxed(rtc->base + regs->sr);
 215         cr = readl_relaxed(rtc->base + regs->cr);
 216
 217         if ((status & evts->alra) &&
 218             (cr & STM32_RTC_CR_ALRAIE)) {
 219                 /* Alarm A flag - Alarm interrupt */
 220                 dev_dbg(&rtc->rtc_dev->dev, "Alarm occurred\n");
 221
 222                 /* Pass event to the kernel */
 223                 rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
 224
 225                 /* Clear event flags, otherwise new events won't be received */
 226                 stm32_rtc_clear_event_flags(rtc, evts->alra);
 227         }
 228
 229         mutex_unlock(&rtc->rtc_dev->ops_lock);
 230
 231         return IRQ_HANDLED;
 232 }
 233
 234 /* Convert rtc_time structure from bin to bcd format */
 235 static void tm2bcd(struct rtc_time *tm)
 236 {
 237         tm->tm_sec = bin2bcd(tm->tm_sec);
 238         tm->tm_min = bin2bcd(tm->tm_min);
 239         tm->tm_hour = bin2bcd(tm->tm_hour);
 240
 241         tm->tm_mday = bin2bcd(tm->tm_mday);
 242         tm->tm_mon = bin2bcd(tm->tm_mon + 1);
 243         tm->tm_year = bin2bcd(tm->tm_year - 100);
 244         /*
 245          * Number of days since Sunday
 246          * - on kernel side, 0=Sunday...6=Saturday
 247          * - on rtc side, 0=invalid,1=Monday...7=Sunday
 248          */
 249         tm->tm_wday = (!tm->tm_wday) ? 7 : tm->tm_wday;
 250 }
 251
 252 /* Convert rtc_time structure from bcd to bin format */
 253 static void bcd2tm(struct rtc_time *tm)
 254 {
 255         tm->tm_sec = bcd2bin(tm->tm_sec);
 256         tm->tm_min = bcd2bin(tm->tm_min);
 257         tm->tm_hour = bcd2bin(tm->tm_hour);
 258
 259         tm->tm_mday = bcd2bin(tm->tm_mday);
 260         tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
 261         tm->tm_year = bcd2bin(tm->tm_year) + 100;
 262         /*
 263          * Number of days since Sunday
 264          * - on kernel side, 0=Sunday...6=Saturday
 265          * - on rtc side, 0=invalid,1=Monday...7=Sunday
 266          */
 267         tm->tm_wday %= 7;
 268 }
 269
 270 static int stm32_rtc_read_time(struct device *dev, struct rtc_time *tm)
 271 {
 272         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 273         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 274         unsigned int tr, dr;
 275
 276         /* Time and Date in BCD format */
 277         tr = readl_relaxed(rtc->base + regs->tr);
 278         dr = readl_relaxed(rtc->base + regs->dr);
 279
 280         tm->tm_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
 281         tm->tm_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
 282         tm->tm_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
 283
 284         tm->tm_mday = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
 285         tm->tm_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
 286         tm->tm_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
 287         tm->tm_wday = (dr & STM32_RTC_DR_WDAY) >> STM32_RTC_DR_WDAY_SHIFT;
 288
 289         /* We don't report tm_yday and tm_isdst */
 290
 291         bcd2tm(tm);
 292
 293         return 0;
 294 }
 295
 296 static int stm32_rtc_set_time(struct device *dev, struct rtc_time *tm)
 297 {
 298         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 299         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 300         unsigned int tr, dr;
 301         int ret = 0;
 302
 303         tm2bcd(tm);
 304
 305         /* Time in BCD format */
 306         tr = ((tm->tm_sec << STM32_RTC_TR_SEC_SHIFT) & STM32_RTC_TR_SEC) |
 307              ((tm->tm_min << STM32_RTC_TR_MIN_SHIFT) & STM32_RTC_TR_MIN) |
 308              ((tm->tm_hour << STM32_RTC_TR_HOUR_SHIFT) & STM32_RTC_TR_HOUR);
 309
 310         /* Date in BCD format */
 311         dr = ((tm->tm_mday << STM32_RTC_DR_DATE_SHIFT) & STM32_RTC_DR_DATE) |
 312              ((tm->tm_mon << STM32_RTC_DR_MONTH_SHIFT) & STM32_RTC_DR_MONTH) |
 313              ((tm->tm_year << STM32_RTC_DR_YEAR_SHIFT) & STM32_RTC_DR_YEAR) |
 314              ((tm->tm_wday << STM32_RTC_DR_WDAY_SHIFT) & STM32_RTC_DR_WDAY);
 315
 316         stm32_rtc_wpr_unlock(rtc);
 317
 318         ret = stm32_rtc_enter_init_mode(rtc);
 319         if (ret) {
 320                 dev_err(dev, "Can't enter in init mode. Set time aborted.\n");
 321                 goto end;
 322         }
 323
 324         writel_relaxed(tr, rtc->base + regs->tr);
 325         writel_relaxed(dr, rtc->base + regs->dr);
 326
 327         stm32_rtc_exit_init_mode(rtc);
 328
 329         ret = stm32_rtc_wait_sync(rtc);
 330 end:
 331         stm32_rtc_wpr_lock(rtc);
 332
 333         return ret;
 334 }
 335
 336 static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 337 {
 338         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 339         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 340         const struct stm32_rtc_events *evts = &rtc->data->events;
 341         struct rtc_time *tm = &alrm->time;
 342         unsigned int alrmar, cr, status;
 343
 344         alrmar = readl_relaxed(rtc->base + regs->alrmar);
 345         cr = readl_relaxed(rtc->base + regs->cr);
 346         status = readl_relaxed(rtc->base + regs->sr);
 347
 348         if (alrmar & STM32_RTC_ALRMXR_DATE_MASK) {
 349                 /*
 350                  * Date/day doesn't matter in Alarm comparison so alarm
 351                  * triggers every day
 352                  */
 353                 tm->tm_mday = -1;
 354                 tm->tm_wday = -1;
 355         } else {
 356                 if (alrmar & STM32_RTC_ALRMXR_WDSEL) {
 357                         /* Alarm is set to a day of week */
 358                         tm->tm_mday = -1;
 359                         tm->tm_wday = (alrmar & STM32_RTC_ALRMXR_WDAY) >>
 360                                       STM32_RTC_ALRMXR_WDAY_SHIFT;
 361                         tm->tm_wday %= 7;
 362                 } else {
 363                         /* Alarm is set to a day of month */
 364                         tm->tm_wday = -1;
 365                         tm->tm_mday = (alrmar & STM32_RTC_ALRMXR_DATE) >>
 366                                        STM32_RTC_ALRMXR_DATE_SHIFT;
 367                 }
 368         }
 369
 370         if (alrmar & STM32_RTC_ALRMXR_HOUR_MASK) {
 371                 /* Hours don't matter in Alarm comparison */
 372                 tm->tm_hour = -1;
 373         } else {
 374                 tm->tm_hour = (alrmar & STM32_RTC_ALRMXR_HOUR) >>
 375                                STM32_RTC_ALRMXR_HOUR_SHIFT;
 376                 if (alrmar & STM32_RTC_ALRMXR_PM)
 377                         tm->tm_hour += 12;
 378         }
 379
 380         if (alrmar & STM32_RTC_ALRMXR_MIN_MASK) {
 381                 /* Minutes don't matter in Alarm comparison */
 382                 tm->tm_min = -1;
 383         } else {
 384                 tm->tm_min = (alrmar & STM32_RTC_ALRMXR_MIN) >>
 385                               STM32_RTC_ALRMXR_MIN_SHIFT;
 386         }
 387
 388         if (alrmar & STM32_RTC_ALRMXR_SEC_MASK) {
 389                 /* Seconds don't matter in Alarm comparison */
 390                 tm->tm_sec = -1;
 391         } else {
 392                 tm->tm_sec = (alrmar & STM32_RTC_ALRMXR_SEC) >>
 393                               STM32_RTC_ALRMXR_SEC_SHIFT;
 394         }
 395
 396         bcd2tm(tm);
 397
 398         alrm->enabled = (cr & STM32_RTC_CR_ALRAE) ? 1 : 0;
 399         alrm->pending = (status & evts->alra) ? 1 : 0;
 400
 401         return 0;
 402 }
 403
 404 static int stm32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 405 {
 406         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 407         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 408         const struct stm32_rtc_events *evts = &rtc->data->events;
 409         unsigned int cr;
 410
 411         cr = readl_relaxed(rtc->base + regs->cr);
 412
 413         stm32_rtc_wpr_unlock(rtc);
 414
 415         /* We expose Alarm A to the kernel */
 416         if (enabled)
 417                 cr |= (STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
 418         else
 419                 cr &= ~(STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
 420         writel_relaxed(cr, rtc->base + regs->cr);
 421
 422         /* Clear event flags, otherwise new events won't be received */
 423         stm32_rtc_clear_event_flags(rtc, evts->alra);
 424
 425         stm32_rtc_wpr_lock(rtc);
 426
 427         return 0;
 428 }
 429
 430 static int stm32_rtc_valid_alrm(struct stm32_rtc *rtc, struct rtc_time *tm)
 431 {
 432         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 433         int cur_day, cur_mon, cur_year, cur_hour, cur_min, cur_sec;
 434         unsigned int dr = readl_relaxed(rtc->base + regs->dr);
 435         unsigned int tr = readl_relaxed(rtc->base + regs->tr);
 436
 437         cur_day = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
 438         cur_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
 439         cur_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
 440         cur_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
 441         cur_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
 442         cur_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
 443
 444         /*
 445          * Assuming current date is M-D-Y H:M:S.
 446          * RTC alarm can't be set on a specific month and year.
 447          * So the valid alarm range is:
 448          *      M-D-Y H:M:S < alarm <= (M+1)-D-Y H:M:S
 449          * with a specific case for December...
 450          */
 451         if ((((tm->tm_year > cur_year) &&
 452               (tm->tm_mon == 0x1) && (cur_mon == 0x12)) ||
 453              ((tm->tm_year == cur_year) &&
 454               (tm->tm_mon <= cur_mon + 1))) &&
 455             ((tm->tm_mday > cur_day) ||
 456              ((tm->tm_mday == cur_day) &&
 457              ((tm->tm_hour > cur_hour) ||
 458               ((tm->tm_hour == cur_hour) && (tm->tm_min > cur_min)) ||
 459               ((tm->tm_hour == cur_hour) && (tm->tm_min == cur_min) &&
 460                (tm->tm_sec >= cur_sec))))))
 461                 return 0;
 462
 463         return -EINVAL;
 464 }
 465
 466 static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 467 {
 468         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 469         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 470         struct rtc_time *tm = &alrm->time;
 471         unsigned int cr, isr, alrmar;
 472         int ret = 0;
 473
 474         tm2bcd(tm);
 475
 476         /*
 477          * RTC alarm can't be set on a specific date, unless this date is
 478          * up to the same day of month next month.
 479          */
 480         if (stm32_rtc_valid_alrm(rtc, tm) < 0) {
 481                 dev_err(dev, "Alarm can be set only on upcoming month.\n");
 482                 return -EINVAL;
 483         }
 484
 485         alrmar = 0;
 486         /* tm_year and tm_mon are not used because not supported by RTC */
 487         alrmar |= (tm->tm_mday << STM32_RTC_ALRMXR_DATE_SHIFT) &
 488                   STM32_RTC_ALRMXR_DATE;
 489         /* 24-hour format */
 490         alrmar &= ~STM32_RTC_ALRMXR_PM;
 491         alrmar |= (tm->tm_hour << STM32_RTC_ALRMXR_HOUR_SHIFT) &
 492                   STM32_RTC_ALRMXR_HOUR;
 493         alrmar |= (tm->tm_min << STM32_RTC_ALRMXR_MIN_SHIFT) &
 494                   STM32_RTC_ALRMXR_MIN;
 495         alrmar |= (tm->tm_sec << STM32_RTC_ALRMXR_SEC_SHIFT) &
 496                   STM32_RTC_ALRMXR_SEC;
 497
 498         stm32_rtc_wpr_unlock(rtc);
 499
 500         /* Disable Alarm */
 501         cr = readl_relaxed(rtc->base + regs->cr);
 502         cr &= ~STM32_RTC_CR_ALRAE;
 503         writel_relaxed(cr, rtc->base + regs->cr);
 504
 505         /*
 506          * Poll Alarm write flag to be sure that Alarm update is allowed: it
 507          * takes around 2 rtc_ck clock cycles
 508          */
 509         ret = readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
 510                                                 isr,
 511                                                 (isr & STM32_RTC_ISR_ALRAWF),
 512                                                 10, 100000);
 513
 514         if (ret) {
 515                 dev_err(dev, "Alarm update not allowed\n");
 516                 goto end;
 517         }
 518
 519         /* Write to Alarm register */
 520         writel_relaxed(alrmar, rtc->base + regs->alrmar);
 521
 522         stm32_rtc_alarm_irq_enable(dev, alrm->enabled);
 523 end:
 524         stm32_rtc_wpr_lock(rtc);
 525
 526         return ret;
 527 }
 528
 529 static const struct rtc_class_ops stm32_rtc_ops = {
 530         .read_time      = stm32_rtc_read_time,
 531         .set_time       = stm32_rtc_set_time,
 532         .read_alarm     = stm32_rtc_read_alarm,
 533         .set_alarm      = stm32_rtc_set_alarm,
 534         .alarm_irq_enable = stm32_rtc_alarm_irq_enable,
 535 };
 536
 537 static void stm32_rtc_clear_events(struct stm32_rtc *rtc,
 538                                    unsigned int flags)
 539 {
 540         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 541
 542         /* Flags are cleared by writing 0 in RTC_ISR */
 543         writel_relaxed(readl_relaxed(rtc->base + regs->isr) & ~flags,
 544                        rtc->base + regs->isr);
 545 }
 546
 547 static const struct stm32_rtc_data stm32_rtc_data = {
 548         .has_pclk = false,
 549         .need_dbp = true,
 550         .has_wakeirq = false,
 551         .regs = {
 552                 .tr = 0x00,
 553                 .dr = 0x04,
 554                 .cr = 0x08,
 555                 .isr = 0x0C,
 556                 .prer = 0x10,
 557                 .alrmar = 0x1C,
 558                 .wpr = 0x24,
 559                 .sr = 0x0C, /* set to ISR offset to ease alarm management */
 560                 .scr = UNDEF_REG,
 561                 .verr = UNDEF_REG,
 562         },
 563         .events = {
 564                 .alra = STM32_RTC_ISR_ALRAF,
 565         },
 566         .clear_events = stm32_rtc_clear_events,
 567 };
 568
 569 static const struct stm32_rtc_data stm32h7_rtc_data = {
 570         .has_pclk = true,
 571         .need_dbp = true,
 572         .has_wakeirq = false,
 573         .regs = {
 574                 .tr = 0x00,
 575                 .dr = 0x04,
 576                 .cr = 0x08,
 577                 .isr = 0x0C,
 578                 .prer = 0x10,
 579                 .alrmar = 0x1C,
 580                 .wpr = 0x24,
 581                 .sr = 0x0C, /* set to ISR offset to ease alarm management */
 582                 .scr = UNDEF_REG,
 583                 .verr = UNDEF_REG,
 584         },
 585         .events = {
 586                 .alra = STM32_RTC_ISR_ALRAF,
 587         },
 588         .clear_events = stm32_rtc_clear_events,
 589 };
 590
 591 static void stm32mp1_rtc_clear_events(struct stm32_rtc *rtc,
 592                                       unsigned int flags)
 593 {
 594         struct stm32_rtc_registers regs = rtc->data->regs;
 595
 596         /* Flags are cleared by writing 1 in RTC_SCR */
 597         writel_relaxed(flags, rtc->base + regs.scr);
 598 }
 599
 600 static const struct stm32_rtc_data stm32mp1_data = {
 601         .has_pclk = true,
 602         .need_dbp = false,
 603         .has_wakeirq = true,
 604         .regs = {
 605                 .tr = 0x00,
 606                 .dr = 0x04,
 607                 .cr = 0x18,
 608                 .isr = 0x0C, /* named RTC_ICSR on stm32mp1 */
 609                 .prer = 0x10,
 610                 .alrmar = 0x40,
 611                 .wpr = 0x24,
 612                 .sr = 0x50,
 613                 .scr = 0x5C,
 614                 .verr = 0x3F4,
 615         },
 616         .events = {
 617                 .alra = STM32_RTC_SR_ALRA,
 618         },
 619         .clear_events = stm32mp1_rtc_clear_events,
 620 };
 621
 622 static const struct of_device_id stm32_rtc_of_match[] = {
 623         { .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
 624         { .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },
 625         { .compatible = "st,stm32mp1-rtc", .data = &stm32mp1_data },
 626         {}
 627 };
 628 MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
 629
 630 static int stm32_rtc_init(struct platform_device *pdev,
 631                           struct stm32_rtc *rtc)
 632 {
 633         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 634         unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
 635         unsigned int rate;
 636         int ret = 0;
 637
 638         rate = clk_get_rate(rtc->rtc_ck);
 639
 640         /* Find prediv_a and prediv_s to obtain the 1Hz calendar clock */
 641         pred_a_max = STM32_RTC_PRER_PRED_A >> STM32_RTC_PRER_PRED_A_SHIFT;
 642         pred_s_max = STM32_RTC_PRER_PRED_S >> STM32_RTC_PRER_PRED_S_SHIFT;
 643
 644         for (pred_a = pred_a_max; pred_a + 1 > 0; pred_a--) {
 645                 pred_s = (rate / (pred_a + 1)) - 1;
 646
 647                 if (((pred_s + 1) * (pred_a + 1)) == rate)
 648                         break;
 649         }
 650
 651         /*
 652          * Can't find a 1Hz, so give priority to RTC power consumption
 653          * by choosing the higher possible value for prediv_a
 654          */
 655         if ((pred_s > pred_s_max) || (pred_a > pred_a_max)) {
 656                 pred_a = pred_a_max;
 657                 pred_s = (rate / (pred_a + 1)) - 1;
 658
 659                 dev_warn(&pdev->dev, "rtc_ck is %s\n",
 660                          (rate < ((pred_a + 1) * (pred_s + 1))) ?
 661                          "fast" : "slow");
 662         }
 663
 664         stm32_rtc_wpr_unlock(rtc);
 665
 666         ret = stm32_rtc_enter_init_mode(rtc);
 667         if (ret) {
 668                 dev_err(&pdev->dev,
 669                         "Can't enter in init mode. Prescaler config failed.\n");
 670                 goto end;
 671         }
 672
 673         prer = (pred_s << STM32_RTC_PRER_PRED_S_SHIFT) & STM32_RTC_PRER_PRED_S;
 674         writel_relaxed(prer, rtc->base + regs->prer);
 675         prer |= (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) & STM32_RTC_PRER_PRED_A;
 676         writel_relaxed(prer, rtc->base + regs->prer);
 677
 678         /* Force 24h time format */
 679         cr = readl_relaxed(rtc->base + regs->cr);
 680         cr &= ~STM32_RTC_CR_FMT;
 681         writel_relaxed(cr, rtc->base + regs->cr);
 682
 683         stm32_rtc_exit_init_mode(rtc);
 684
 685         ret = stm32_rtc_wait_sync(rtc);
 686 end:
 687         stm32_rtc_wpr_lock(rtc);
 688
 689         return ret;
 690 }
 691
 692 static int stm32_rtc_probe(struct platform_device *pdev)
 693 {
 694         struct stm32_rtc *rtc;
 695         const struct stm32_rtc_registers *regs;
 696         int ret;
 697
 698         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 699         if (!rtc)
 700                 return -ENOMEM;
 701
 702         rtc->base = devm_platform_ioremap_resource(pdev, 0);
 703         if (IS_ERR(rtc->base))
 704                 return PTR_ERR(rtc->base);
 705
 706         rtc->data = (struct stm32_rtc_data *)
 707                     of_device_get_match_data(&pdev->dev);
 708         regs = &rtc->data->regs;
 709
 710         if (rtc->data->need_dbp) {
 711                 rtc->dbp = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 712                                                            "st,syscfg");
 713                 if (IS_ERR(rtc->dbp)) {
 714                         dev_err(&pdev->dev, "no st,syscfg\n");
 715                         return PTR_ERR(rtc->dbp);
 716                 }
 717
 718                 ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
 719                                                  1, &rtc->dbp_reg);
 720                 if (ret) {
 721                         dev_err(&pdev->dev, "can't read DBP register offset\n");
 722                         return ret;
 723                 }
 724
 725                 ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
 726                                                  2, &rtc->dbp_mask);
 727                 if (ret) {
 728                         dev_err(&pdev->dev, "can't read DBP register mask\n");
 729                         return ret;
 730                 }
 731         }
 732
 733         if (!rtc->data->has_pclk) {
 734                 rtc->pclk = NULL;
 735                 rtc->rtc_ck = devm_clk_get(&pdev->dev, NULL);
 736         } else {
 737                 rtc->pclk = devm_clk_get(&pdev->dev, "pclk");
 738                 if (IS_ERR(rtc->pclk)) {
 739                         dev_err(&pdev->dev, "no pclk clock");
 740                         return PTR_ERR(rtc->pclk);
 741                 }
 742                 rtc->rtc_ck = devm_clk_get(&pdev->dev, "rtc_ck");
 743         }
 744         if (IS_ERR(rtc->rtc_ck)) {
 745                 dev_err(&pdev->dev, "no rtc_ck clock");
 746                 return PTR_ERR(rtc->rtc_ck);
 747         }
 748
 749         if (rtc->data->has_pclk) {
 750                 ret = clk_prepare_enable(rtc->pclk);
 751                 if (ret)
 752                         return ret;
 753         }
 754
 755         ret = clk_prepare_enable(rtc->rtc_ck);
 756         if (ret)
 757                 goto err;
 758
 759         if (rtc->data->need_dbp)
 760                 regmap_update_bits(rtc->dbp, rtc->dbp_reg,
 761                                    rtc->dbp_mask, rtc->dbp_mask);
 762
 763         /*
 764          * After a system reset, RTC_ISR.INITS flag can be read to check if
 765          * the calendar has been initialized or not. INITS flag is reset by a
 766          * power-on reset (no vbat, no power-supply). It is not reset if
 767          * rtc_ck parent clock has changed (so RTC prescalers need to be
 768          * changed). That's why we cannot rely on this flag to know if RTC
 769          * init has to be done.
 770          */
 771         ret = stm32_rtc_init(pdev, rtc);
 772         if (ret)
 773                 goto err;
 774
 775         rtc->irq_alarm = platform_get_irq(pdev, 0);
 776         if (rtc->irq_alarm <= 0) {
 777                 ret = rtc->irq_alarm;
 778                 goto err;
 779         }
 780
 781         ret = device_init_wakeup(&pdev->dev, true);
 782         if (rtc->data->has_wakeirq) {
 783                 rtc->wakeirq_alarm = platform_get_irq(pdev, 1);
 784                 if (rtc->wakeirq_alarm > 0) {
 785                         ret = dev_pm_set_dedicated_wake_irq(&pdev->dev,
 786                                                             rtc->wakeirq_alarm);
 787                 } else {
 788                         ret = rtc->wakeirq_alarm;
 789                         if (rtc->wakeirq_alarm == -EPROBE_DEFER)
 790                                 goto err;
 791                 }
 792         }
 793         if (ret)
 794                 dev_warn(&pdev->dev, "alarm can't wake up the system: %d", ret);
 795
 796         platform_set_drvdata(pdev, rtc);
 797
 798         rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
 799                                                 &stm32_rtc_ops, THIS_MODULE);
 800         if (IS_ERR(rtc->rtc_dev)) {
 801                 ret = PTR_ERR(rtc->rtc_dev);
 802                 dev_err(&pdev->dev, "rtc device registration failed, err=%d\n",
 803                         ret);
 804                 goto err;
 805         }
 806
 807         /* Handle RTC alarm interrupts */
 808         ret = devm_request_threaded_irq(&pdev->dev, rtc->irq_alarm, NULL,
 809                                         stm32_rtc_alarm_irq, IRQF_ONESHOT,
 810                                         pdev->name, rtc);
 811         if (ret) {
 812                 dev_err(&pdev->dev, "IRQ%d (alarm interrupt) already claimed\n",
 813                         rtc->irq_alarm);
 814                 goto err;
 815         }
 816
 817         /*
 818          * If INITS flag is reset (calendar year field set to 0x00), calendar
 819          * must be initialized
 820          */
 821         if (!(readl_relaxed(rtc->base + regs->isr) & STM32_RTC_ISR_INITS))
 822                 dev_warn(&pdev->dev, "Date/Time must be initialized\n");
 823
 824         if (regs->verr != UNDEF_REG) {
 825                 u32 ver = readl_relaxed(rtc->base + regs->verr);
 826
 827                 dev_info(&pdev->dev, "registered rev:%d.%d\n",
 828                          (ver >> STM32_RTC_VERR_MAJREV_SHIFT) & 0xF,
 829                          (ver >> STM32_RTC_VERR_MINREV_SHIFT) & 0xF);
 830         }
 831
 832         return 0;
 833 err:
 834         if (rtc->data->has_pclk)
 835                 clk_disable_unprepare(rtc->pclk);
 836         clk_disable_unprepare(rtc->rtc_ck);
 837
 838         if (rtc->data->need_dbp)
 839                 regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
 840
 841         dev_pm_clear_wake_irq(&pdev->dev);
 842         device_init_wakeup(&pdev->dev, false);
 843
 844         return ret;
 845 }
 846
 847 static int stm32_rtc_remove(struct platform_device *pdev)
 848 {
 849         struct stm32_rtc *rtc = platform_get_drvdata(pdev);
 850         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 851         unsigned int cr;
 852
 853         /* Disable interrupts */
 854         stm32_rtc_wpr_unlock(rtc);
 855         cr = readl_relaxed(rtc->base + regs->cr);
 856         cr &= ~STM32_RTC_CR_ALRAIE;
 857         writel_relaxed(cr, rtc->base + regs->cr);
 858         stm32_rtc_wpr_lock(rtc);
 859
 860         clk_disable_unprepare(rtc->rtc_ck);
 861         if (rtc->data->has_pclk)
 862                 clk_disable_unprepare(rtc->pclk);
 863
 864         /* Enable backup domain write protection if needed */
 865         if (rtc->data->need_dbp)
 866                 regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
 867
 868         dev_pm_clear_wake_irq(&pdev->dev);
 869         device_init_wakeup(&pdev->dev, false);
 870
 871         return 0;
 872 }
 873
 874 #ifdef CONFIG_PM_SLEEP
 875 static int stm32_rtc_suspend(struct device *dev)
 876 {
 877         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 878
 879         if (rtc->data->has_pclk)
 880                 clk_disable_unprepare(rtc->pclk);
 881
 882         if (device_may_wakeup(dev))
 883                 return enable_irq_wake(rtc->irq_alarm);
 884
 885         return 0;
 886 }
 887
 888 static int stm32_rtc_resume(struct device *dev)
 889 {
 890         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 891         int ret = 0;
 892
 893         if (rtc->data->has_pclk) {
 894                 ret = clk_prepare_enable(rtc->pclk);
 895                 if (ret)
 896                         return ret;
 897         }
 898
 899         ret = stm32_rtc_wait_sync(rtc);
 900         if (ret < 0) {
 901                 if (rtc->data->has_pclk)
 902                         clk_disable_unprepare(rtc->pclk);
 903                 return ret;
 904         }
 905
 906         if (device_may_wakeup(dev))
 907                 return disable_irq_wake(rtc->irq_alarm);
 908
 909         return ret;
 910 }
 911 #endif
 912
 913 static SIMPLE_DEV_PM_OPS(stm32_rtc_pm_ops,
 914                          stm32_rtc_suspend, stm32_rtc_resume);
 915
 916 static struct platform_driver stm32_rtc_driver = {
 917         .probe          = stm32_rtc_probe,
 918         .remove         = stm32_rtc_remove,
 919         .driver         = {
 920                 .name   = DRIVER_NAME,
 921                 .pm     = &stm32_rtc_pm_ops,
 922                 .of_match_table = stm32_rtc_of_match,
 923         },
 924 };
 925
 926 module_platform_driver(stm32_rtc_driver);
 927
 928 MODULE_ALIAS("platform:" DRIVER_NAME);
 929 MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
 930 MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");
 931 MODULE_LICENSE("GPL v2");