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/errno.h>
  10 #include <linux/iopoll.h>
  11 #include <linux/ioport.h>
  12 #include <linux/mfd/syscon.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/pm_wakeirq.h>
  17 #include <linux/regmap.h>
  18 #include <linux/rtc.h>
  19
  20 #define DRIVER_NAME "stm32_rtc"
  21
  22 /* STM32_RTC_TR bit fields  */
  23 #define STM32_RTC_TR_SEC_SHIFT          0
  24 #define STM32_RTC_TR_SEC                GENMASK(6, 0)
  25 #define STM32_RTC_TR_MIN_SHIFT          8
  26 #define STM32_RTC_TR_MIN                GENMASK(14, 8)
  27 #define STM32_RTC_TR_HOUR_SHIFT         16
  28 #define STM32_RTC_TR_HOUR               GENMASK(21, 16)
  29
  30 /* STM32_RTC_DR bit fields */
  31 #define STM32_RTC_DR_DATE_SHIFT         0
  32 #define STM32_RTC_DR_DATE               GENMASK(5, 0)
  33 #define STM32_RTC_DR_MONTH_SHIFT        8
  34 #define STM32_RTC_DR_MONTH              GENMASK(12, 8)
  35 #define STM32_RTC_DR_WDAY_SHIFT         13
  36 #define STM32_RTC_DR_WDAY               GENMASK(15, 13)
  37 #define STM32_RTC_DR_YEAR_SHIFT         16
  38 #define STM32_RTC_DR_YEAR               GENMASK(23, 16)
  39
  40 /* STM32_RTC_CR bit fields */
  41 #define STM32_RTC_CR_FMT                BIT(6)
  42 #define STM32_RTC_CR_ALRAE              BIT(8)
  43 #define STM32_RTC_CR_ALRAIE             BIT(12)
  44
  45 /* STM32_RTC_ISR/STM32_RTC_ICSR bit fields */
  46 #define STM32_RTC_ISR_ALRAWF            BIT(0)
  47 #define STM32_RTC_ISR_INITS             BIT(4)
  48 #define STM32_RTC_ISR_RSF               BIT(5)
  49 #define STM32_RTC_ISR_INITF             BIT(6)
  50 #define STM32_RTC_ISR_INIT              BIT(7)
  51 #define STM32_RTC_ISR_ALRAF             BIT(8)
  52
  53 /* STM32_RTC_PRER bit fields */
  54 #define STM32_RTC_PRER_PRED_S_SHIFT     0
  55 #define STM32_RTC_PRER_PRED_S           GENMASK(14, 0)
  56 #define STM32_RTC_PRER_PRED_A_SHIFT     16
  57 #define STM32_RTC_PRER_PRED_A           GENMASK(22, 16)
  58
  59 /* STM32_RTC_ALRMAR and STM32_RTC_ALRMBR bit fields */
  60 #define STM32_RTC_ALRMXR_SEC_SHIFT      0
  61 #define STM32_RTC_ALRMXR_SEC            GENMASK(6, 0)
  62 #define STM32_RTC_ALRMXR_SEC_MASK       BIT(7)
  63 #define STM32_RTC_ALRMXR_MIN_SHIFT      8
  64 #define STM32_RTC_ALRMXR_MIN            GENMASK(14, 8)
  65 #define STM32_RTC_ALRMXR_MIN_MASK       BIT(15)
  66 #define STM32_RTC_ALRMXR_HOUR_SHIFT     16
  67 #define STM32_RTC_ALRMXR_HOUR           GENMASK(21, 16)
  68 #define STM32_RTC_ALRMXR_PM             BIT(22)
  69 #define STM32_RTC_ALRMXR_HOUR_MASK      BIT(23)
  70 #define STM32_RTC_ALRMXR_DATE_SHIFT     24
  71 #define STM32_RTC_ALRMXR_DATE           GENMASK(29, 24)
  72 #define STM32_RTC_ALRMXR_WDSEL          BIT(30)
  73 #define STM32_RTC_ALRMXR_WDAY_SHIFT     24
  74 #define STM32_RTC_ALRMXR_WDAY           GENMASK(27, 24)
  75 #define STM32_RTC_ALRMXR_DATE_MASK      BIT(31)
  76
  77 /* STM32_RTC_SR/_SCR bit fields */
  78 #define STM32_RTC_SR_ALRA               BIT(0)
  79
  80 /* STM32_RTC_VERR bit fields */
  81 #define STM32_RTC_VERR_MINREV_SHIFT     0
  82 #define STM32_RTC_VERR_MINREV           GENMASK(3, 0)
  83 #define STM32_RTC_VERR_MAJREV_SHIFT     4
  84 #define STM32_RTC_VERR_MAJREV           GENMASK(7, 4)
  85
  86 /* STM32_RTC_WPR key constants */
  87 #define RTC_WPR_1ST_KEY                 0xCA
  88 #define RTC_WPR_2ND_KEY                 0x53
  89 #define RTC_WPR_WRONG_KEY               0xFF
  90
  91 /* Max STM32 RTC register offset is 0x3FC */
  92 #define UNDEF_REG                       0xFFFF
  93
  94 /* STM32 RTC driver time helpers */
  95 #define SEC_PER_DAY             (24 * 60 * 60)
  96
  97 struct stm32_rtc;
  98
  99 struct stm32_rtc_registers {
 100         u16 tr;
 101         u16 dr;
 102         u16 cr;
 103         u16 isr;
 104         u16 prer;
 105         u16 alrmar;
 106         u16 wpr;
 107         u16 sr;
 108         u16 scr;
 109         u16 verr;
 110 };
 111
 112 struct stm32_rtc_events {
 113         u32 alra;
 114 };
 115
 116 struct stm32_rtc_data {
 117         const struct stm32_rtc_registers regs;
 118         const struct stm32_rtc_events events;
 119         void (*clear_events)(struct stm32_rtc *rtc, unsigned int flags);
 120         bool has_pclk;
 121         bool need_dbp;
 122         bool need_accuracy;
 123 };
 124
 125 struct stm32_rtc {
 126         struct rtc_device *rtc_dev;
 127         void __iomem *base;
 128         struct regmap *dbp;
 129         unsigned int dbp_reg;
 130         unsigned int dbp_mask;
 131         struct clk *pclk;
 132         struct clk *rtc_ck;
 133         const struct stm32_rtc_data *data;
 134         int irq_alarm;
 135 };
 136
 137 static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
 138 {
 139         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 140
 141         writel_relaxed(RTC_WPR_1ST_KEY, rtc->base + regs->wpr);
 142         writel_relaxed(RTC_WPR_2ND_KEY, rtc->base + regs->wpr);
 143 }
 144
 145 static void stm32_rtc_wpr_lock(struct stm32_rtc *rtc)
 146 {
 147         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 148
 149         writel_relaxed(RTC_WPR_WRONG_KEY, rtc->base + regs->wpr);
 150 }
 151
 152 static int stm32_rtc_enter_init_mode(struct stm32_rtc *rtc)
 153 {
 154         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 155         unsigned int isr = readl_relaxed(rtc->base + regs->isr);
 156
 157         if (!(isr & STM32_RTC_ISR_INITF)) {
 158                 isr |= STM32_RTC_ISR_INIT;
 159                 writel_relaxed(isr, rtc->base + regs->isr);
 160
 161                 /*
 162                  * It takes around 2 rtc_ck clock cycles to enter in
 163                  * initialization phase mode (and have INITF flag set). As
 164                  * slowest rtc_ck frequency may be 32kHz and highest should be
 165                  * 1MHz, we poll every 10 us with a timeout of 100ms.
 166                  */
 167                 return readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr, isr,
 168                                                          (isr & STM32_RTC_ISR_INITF),
 169                                                          10, 100000);
 170         }
 171
 172         return 0;
 173 }
 174
 175 static void stm32_rtc_exit_init_mode(struct stm32_rtc *rtc)
 176 {
 177         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 178         unsigned int isr = readl_relaxed(rtc->base + regs->isr);
 179
 180         isr &= ~STM32_RTC_ISR_INIT;
 181         writel_relaxed(isr, rtc->base + regs->isr);
 182 }
 183
 184 static int stm32_rtc_wait_sync(struct stm32_rtc *rtc)
 185 {
 186         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 187         unsigned int isr = readl_relaxed(rtc->base + regs->isr);
 188
 189         isr &= ~STM32_RTC_ISR_RSF;
 190         writel_relaxed(isr, rtc->base + regs->isr);
 191
 192         /*
 193          * Wait for RSF to be set to ensure the calendar registers are
 194          * synchronised, it takes around 2 rtc_ck clock cycles
 195          */
 196         return readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
 197                                                  isr,
 198                                                  (isr & STM32_RTC_ISR_RSF),
 199                                                  10, 100000);
 200 }
 201
 202 static void stm32_rtc_clear_event_flags(struct stm32_rtc *rtc,
 203                                         unsigned int flags)
 204 {
 205         rtc->data->clear_events(rtc, flags);
 206 }
 207
 208 static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
 209 {
 210         struct stm32_rtc *rtc = (struct stm32_rtc *)dev_id;
 211         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 212         const struct stm32_rtc_events *evts = &rtc->data->events;
 213         unsigned int status, cr;
 214
 215         rtc_lock(rtc->rtc_dev);
 216
 217         status = readl_relaxed(rtc->base + regs->sr);
 218         cr = readl_relaxed(rtc->base + regs->cr);
 219
 220         if ((status & evts->alra) &&
 221             (cr & STM32_RTC_CR_ALRAIE)) {
 222                 /* Alarm A flag - Alarm interrupt */
 223                 dev_dbg(&rtc->rtc_dev->dev, "Alarm occurred\n");
 224
 225                 /* Pass event to the kernel */
 226                 rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
 227
 228                 /* Clear event flags, otherwise new events won't be received */
 229                 stm32_rtc_clear_event_flags(rtc, evts->alra);
 230         }
 231
 232         rtc_unlock(rtc->rtc_dev);
 233
 234         return IRQ_HANDLED;
 235 }
 236
 237 /* Convert rtc_time structure from bin to bcd format */
 238 static void tm2bcd(struct rtc_time *tm)
 239 {
 240         tm->tm_sec = bin2bcd(tm->tm_sec);
 241         tm->tm_min = bin2bcd(tm->tm_min);
 242         tm->tm_hour = bin2bcd(tm->tm_hour);
 243
 244         tm->tm_mday = bin2bcd(tm->tm_mday);
 245         tm->tm_mon = bin2bcd(tm->tm_mon + 1);
 246         tm->tm_year = bin2bcd(tm->tm_year - 100);
 247         /*
 248          * Number of days since Sunday
 249          * - on kernel side, 0=Sunday...6=Saturday
 250          * - on rtc side, 0=invalid,1=Monday...7=Sunday
 251          */
 252         tm->tm_wday = (!tm->tm_wday) ? 7 : tm->tm_wday;
 253 }
 254
 255 /* Convert rtc_time structure from bcd to bin format */
 256 static void bcd2tm(struct rtc_time *tm)
 257 {
 258         tm->tm_sec = bcd2bin(tm->tm_sec);
 259         tm->tm_min = bcd2bin(tm->tm_min);
 260         tm->tm_hour = bcd2bin(tm->tm_hour);
 261
 262         tm->tm_mday = bcd2bin(tm->tm_mday);
 263         tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
 264         tm->tm_year = bcd2bin(tm->tm_year) + 100;
 265         /*
 266          * Number of days since Sunday
 267          * - on kernel side, 0=Sunday...6=Saturday
 268          * - on rtc side, 0=invalid,1=Monday...7=Sunday
 269          */
 270         tm->tm_wday %= 7;
 271 }
 272
 273 static int stm32_rtc_read_time(struct device *dev, struct rtc_time *tm)
 274 {
 275         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 276         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 277         unsigned int tr, dr;
 278
 279         /* Time and Date in BCD format */
 280         tr = readl_relaxed(rtc->base + regs->tr);
 281         dr = readl_relaxed(rtc->base + regs->dr);
 282
 283         tm->tm_sec = (tr & STM32_RTC_TR_SEC) >> STM32_RTC_TR_SEC_SHIFT;
 284         tm->tm_min = (tr & STM32_RTC_TR_MIN) >> STM32_RTC_TR_MIN_SHIFT;
 285         tm->tm_hour = (tr & STM32_RTC_TR_HOUR) >> STM32_RTC_TR_HOUR_SHIFT;
 286
 287         tm->tm_mday = (dr & STM32_RTC_DR_DATE) >> STM32_RTC_DR_DATE_SHIFT;
 288         tm->tm_mon = (dr & STM32_RTC_DR_MONTH) >> STM32_RTC_DR_MONTH_SHIFT;
 289         tm->tm_year = (dr & STM32_RTC_DR_YEAR) >> STM32_RTC_DR_YEAR_SHIFT;
 290         tm->tm_wday = (dr & STM32_RTC_DR_WDAY) >> STM32_RTC_DR_WDAY_SHIFT;
 291
 292         /* We don't report tm_yday and tm_isdst */
 293
 294         bcd2tm(tm);
 295
 296         return 0;
 297 }
 298
 299 static int stm32_rtc_set_time(struct device *dev, struct rtc_time *tm)
 300 {
 301         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 302         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 303         unsigned int tr, dr;
 304         int ret = 0;
 305
 306         tm2bcd(tm);
 307
 308         /* Time in BCD format */
 309         tr = ((tm->tm_sec << STM32_RTC_TR_SEC_SHIFT) & STM32_RTC_TR_SEC) |
 310              ((tm->tm_min << STM32_RTC_TR_MIN_SHIFT) & STM32_RTC_TR_MIN) |
 311              ((tm->tm_hour << STM32_RTC_TR_HOUR_SHIFT) & STM32_RTC_TR_HOUR);
 312
 313         /* Date in BCD format */
 314         dr = ((tm->tm_mday << STM32_RTC_DR_DATE_SHIFT) & STM32_RTC_DR_DATE) |
 315              ((tm->tm_mon << STM32_RTC_DR_MONTH_SHIFT) & STM32_RTC_DR_MONTH) |
 316              ((tm->tm_year << STM32_RTC_DR_YEAR_SHIFT) & STM32_RTC_DR_YEAR) |
 317              ((tm->tm_wday << STM32_RTC_DR_WDAY_SHIFT) & STM32_RTC_DR_WDAY);
 318
 319         stm32_rtc_wpr_unlock(rtc);
 320
 321         ret = stm32_rtc_enter_init_mode(rtc);
 322         if (ret) {
 323                 dev_err(dev, "Can't enter in init mode. Set time aborted.\n");
 324                 goto end;
 325         }
 326
 327         writel_relaxed(tr, rtc->base + regs->tr);
 328         writel_relaxed(dr, rtc->base + regs->dr);
 329
 330         stm32_rtc_exit_init_mode(rtc);
 331
 332         ret = stm32_rtc_wait_sync(rtc);
 333 end:
 334         stm32_rtc_wpr_lock(rtc);
 335
 336         return ret;
 337 }
 338
 339 static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 340 {
 341         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 342         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 343         const struct stm32_rtc_events *evts = &rtc->data->events;
 344         struct rtc_time *tm = &alrm->time;
 345         unsigned int alrmar, cr, status;
 346
 347         alrmar = readl_relaxed(rtc->base + regs->alrmar);
 348         cr = readl_relaxed(rtc->base + regs->cr);
 349         status = readl_relaxed(rtc->base + regs->sr);
 350
 351         if (alrmar & STM32_RTC_ALRMXR_DATE_MASK) {
 352                 /*
 353                  * Date/day doesn't matter in Alarm comparison so alarm
 354                  * triggers every day
 355                  */
 356                 tm->tm_mday = -1;
 357                 tm->tm_wday = -1;
 358         } else {
 359                 if (alrmar & STM32_RTC_ALRMXR_WDSEL) {
 360                         /* Alarm is set to a day of week */
 361                         tm->tm_mday = -1;
 362                         tm->tm_wday = (alrmar & STM32_RTC_ALRMXR_WDAY) >>
 363                                       STM32_RTC_ALRMXR_WDAY_SHIFT;
 364                         tm->tm_wday %= 7;
 365                 } else {
 366                         /* Alarm is set to a day of month */
 367                         tm->tm_wday = -1;
 368                         tm->tm_mday = (alrmar & STM32_RTC_ALRMXR_DATE) >>
 369                                        STM32_RTC_ALRMXR_DATE_SHIFT;
 370                 }
 371         }
 372
 373         if (alrmar & STM32_RTC_ALRMXR_HOUR_MASK) {
 374                 /* Hours don't matter in Alarm comparison */
 375                 tm->tm_hour = -1;
 376         } else {
 377                 tm->tm_hour = (alrmar & STM32_RTC_ALRMXR_HOUR) >>
 378                                STM32_RTC_ALRMXR_HOUR_SHIFT;
 379                 if (alrmar & STM32_RTC_ALRMXR_PM)
 380                         tm->tm_hour += 12;
 381         }
 382
 383         if (alrmar & STM32_RTC_ALRMXR_MIN_MASK) {
 384                 /* Minutes don't matter in Alarm comparison */
 385                 tm->tm_min = -1;
 386         } else {
 387                 tm->tm_min = (alrmar & STM32_RTC_ALRMXR_MIN) >>
 388                               STM32_RTC_ALRMXR_MIN_SHIFT;
 389         }
 390
 391         if (alrmar & STM32_RTC_ALRMXR_SEC_MASK) {
 392                 /* Seconds don't matter in Alarm comparison */
 393                 tm->tm_sec = -1;
 394         } else {
 395                 tm->tm_sec = (alrmar & STM32_RTC_ALRMXR_SEC) >>
 396                               STM32_RTC_ALRMXR_SEC_SHIFT;
 397         }
 398
 399         bcd2tm(tm);
 400
 401         alrm->enabled = (cr & STM32_RTC_CR_ALRAE) ? 1 : 0;
 402         alrm->pending = (status & evts->alra) ? 1 : 0;
 403
 404         return 0;
 405 }
 406
 407 static int stm32_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 408 {
 409         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 410         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 411         const struct stm32_rtc_events *evts = &rtc->data->events;
 412         unsigned int cr;
 413
 414         cr = readl_relaxed(rtc->base + regs->cr);
 415
 416         stm32_rtc_wpr_unlock(rtc);
 417
 418         /* We expose Alarm A to the kernel */
 419         if (enabled)
 420                 cr |= (STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
 421         else
 422                 cr &= ~(STM32_RTC_CR_ALRAIE | STM32_RTC_CR_ALRAE);
 423         writel_relaxed(cr, rtc->base + regs->cr);
 424
 425         /* Clear event flags, otherwise new events won't be received */
 426         stm32_rtc_clear_event_flags(rtc, evts->alra);
 427
 428         stm32_rtc_wpr_lock(rtc);
 429
 430         return 0;
 431 }
 432
 433 static int stm32_rtc_valid_alrm(struct device *dev, struct rtc_time *tm)
 434 {
 435         static struct rtc_time now;
 436         time64_t max_alarm_time64;
 437         int max_day_forward;
 438         int next_month;
 439         int next_year;
 440
 441         /*
 442          * Assuming current date is M-D-Y H:M:S.
 443          * RTC alarm can't be set on a specific month and year.
 444          * So the valid alarm range is:
 445          *      M-D-Y H:M:S < alarm <= (M+1)-D-Y H:M:S
 446          */
 447         stm32_rtc_read_time(dev, &now);
 448
 449         /*
 450          * Find the next month and the year of the next month.
 451          * Note: tm_mon and next_month are from 0 to 11
 452          */
 453         next_month = now.tm_mon + 1;
 454         if (next_month == 12) {
 455                 next_month = 0;
 456                 next_year = now.tm_year + 1;
 457         } else {
 458                 next_year = now.tm_year;
 459         }
 460
 461         /* Find the maximum limit of alarm in days. */
 462         max_day_forward = rtc_month_days(now.tm_mon, now.tm_year)
 463                          - now.tm_mday
 464                          + min(rtc_month_days(next_month, next_year), now.tm_mday);
 465
 466         /* Convert to timestamp and compare the alarm time and its upper limit */
 467         max_alarm_time64 = rtc_tm_to_time64(&now) + max_day_forward * SEC_PER_DAY;
 468         return rtc_tm_to_time64(tm) <= max_alarm_time64 ? 0 : -EINVAL;
 469 }
 470
 471 static int stm32_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 472 {
 473         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 474         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 475         struct rtc_time *tm = &alrm->time;
 476         unsigned int cr, isr, alrmar;
 477         int ret = 0;
 478
 479         /*
 480          * RTC alarm can't be set on a specific date, unless this date is
 481          * up to the same day of month next month.
 482          */
 483         if (stm32_rtc_valid_alrm(dev, tm) < 0) {
 484                 dev_err(dev, "Alarm can be set only on upcoming month.\n");
 485                 return -EINVAL;
 486         }
 487
 488         tm2bcd(tm);
 489
 490         alrmar = 0;
 491         /* tm_year and tm_mon are not used because not supported by RTC */
 492         alrmar |= (tm->tm_mday << STM32_RTC_ALRMXR_DATE_SHIFT) &
 493                   STM32_RTC_ALRMXR_DATE;
 494         /* 24-hour format */
 495         alrmar &= ~STM32_RTC_ALRMXR_PM;
 496         alrmar |= (tm->tm_hour << STM32_RTC_ALRMXR_HOUR_SHIFT) &
 497                   STM32_RTC_ALRMXR_HOUR;
 498         alrmar |= (tm->tm_min << STM32_RTC_ALRMXR_MIN_SHIFT) &
 499                   STM32_RTC_ALRMXR_MIN;
 500         alrmar |= (tm->tm_sec << STM32_RTC_ALRMXR_SEC_SHIFT) &
 501                   STM32_RTC_ALRMXR_SEC;
 502
 503         stm32_rtc_wpr_unlock(rtc);
 504
 505         /* Disable Alarm */
 506         cr = readl_relaxed(rtc->base + regs->cr);
 507         cr &= ~STM32_RTC_CR_ALRAE;
 508         writel_relaxed(cr, rtc->base + regs->cr);
 509
 510         /*
 511          * Poll Alarm write flag to be sure that Alarm update is allowed: it
 512          * takes around 2 rtc_ck clock cycles
 513          */
 514         ret = readl_relaxed_poll_timeout_atomic(rtc->base + regs->isr,
 515                                                 isr,
 516                                                 (isr & STM32_RTC_ISR_ALRAWF),
 517                                                 10, 100000);
 518
 519         if (ret) {
 520                 dev_err(dev, "Alarm update not allowed\n");
 521                 goto end;
 522         }
 523
 524         /* Write to Alarm register */
 525         writel_relaxed(alrmar, rtc->base + regs->alrmar);
 526
 527         stm32_rtc_alarm_irq_enable(dev, alrm->enabled);
 528 end:
 529         stm32_rtc_wpr_lock(rtc);
 530
 531         return ret;
 532 }
 533
 534 static const struct rtc_class_ops stm32_rtc_ops = {
 535         .read_time      = stm32_rtc_read_time,
 536         .set_time       = stm32_rtc_set_time,
 537         .read_alarm     = stm32_rtc_read_alarm,
 538         .set_alarm      = stm32_rtc_set_alarm,
 539         .alarm_irq_enable = stm32_rtc_alarm_irq_enable,
 540 };
 541
 542 static void stm32_rtc_clear_events(struct stm32_rtc *rtc,
 543                                    unsigned int flags)
 544 {
 545         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 546
 547         /* Flags are cleared by writing 0 in RTC_ISR */
 548         writel_relaxed(readl_relaxed(rtc->base + regs->isr) & ~flags,
 549                        rtc->base + regs->isr);
 550 }
 551
 552 static const struct stm32_rtc_data stm32_rtc_data = {
 553         .has_pclk = false,
 554         .need_dbp = true,
 555         .need_accuracy = false,
 556         .regs = {
 557                 .tr = 0x00,
 558                 .dr = 0x04,
 559                 .cr = 0x08,
 560                 .isr = 0x0C,
 561                 .prer = 0x10,
 562                 .alrmar = 0x1C,
 563                 .wpr = 0x24,
 564                 .sr = 0x0C, /* set to ISR offset to ease alarm management */
 565                 .scr = UNDEF_REG,
 566                 .verr = UNDEF_REG,
 567         },
 568         .events = {
 569                 .alra = STM32_RTC_ISR_ALRAF,
 570         },
 571         .clear_events = stm32_rtc_clear_events,
 572 };
 573
 574 static const struct stm32_rtc_data stm32h7_rtc_data = {
 575         .has_pclk = true,
 576         .need_dbp = true,
 577         .need_accuracy = false,
 578         .regs = {
 579                 .tr = 0x00,
 580                 .dr = 0x04,
 581                 .cr = 0x08,
 582                 .isr = 0x0C,
 583                 .prer = 0x10,
 584                 .alrmar = 0x1C,
 585                 .wpr = 0x24,
 586                 .sr = 0x0C, /* set to ISR offset to ease alarm management */
 587                 .scr = UNDEF_REG,
 588                 .verr = UNDEF_REG,
 589         },
 590         .events = {
 591                 .alra = STM32_RTC_ISR_ALRAF,
 592         },
 593         .clear_events = stm32_rtc_clear_events,
 594 };
 595
 596 static void stm32mp1_rtc_clear_events(struct stm32_rtc *rtc,
 597                                       unsigned int flags)
 598 {
 599         struct stm32_rtc_registers regs = rtc->data->regs;
 600
 601         /* Flags are cleared by writing 1 in RTC_SCR */
 602         writel_relaxed(flags, rtc->base + regs.scr);
 603 }
 604
 605 static const struct stm32_rtc_data stm32mp1_data = {
 606         .has_pclk = true,
 607         .need_dbp = false,
 608         .need_accuracy = true,
 609         .regs = {
 610                 .tr = 0x00,
 611                 .dr = 0x04,
 612                 .cr = 0x18,
 613                 .isr = 0x0C, /* named RTC_ICSR on stm32mp1 */
 614                 .prer = 0x10,
 615                 .alrmar = 0x40,
 616                 .wpr = 0x24,
 617                 .sr = 0x50,
 618                 .scr = 0x5C,
 619                 .verr = 0x3F4,
 620         },
 621         .events = {
 622                 .alra = STM32_RTC_SR_ALRA,
 623         },
 624         .clear_events = stm32mp1_rtc_clear_events,
 625 };
 626
 627 static const struct of_device_id stm32_rtc_of_match[] = {
 628         { .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
 629         { .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },
 630         { .compatible = "st,stm32mp1-rtc", .data = &stm32mp1_data },
 631         {}
 632 };
 633 MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
 634
 635 static int stm32_rtc_init(struct platform_device *pdev,
 636                           struct stm32_rtc *rtc)
 637 {
 638         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 639         unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
 640         unsigned int rate;
 641         int ret;
 642
 643         rate = clk_get_rate(rtc->rtc_ck);
 644
 645         /* Find prediv_a and prediv_s to obtain the 1Hz calendar clock */
 646         pred_a_max = STM32_RTC_PRER_PRED_A >> STM32_RTC_PRER_PRED_A_SHIFT;
 647         pred_s_max = STM32_RTC_PRER_PRED_S >> STM32_RTC_PRER_PRED_S_SHIFT;
 648
 649         if (rate > (pred_a_max + 1) * (pred_s_max + 1)) {
 650                 dev_err(&pdev->dev, "rtc_ck rate is too high: %dHz\n", rate);
 651                 return -EINVAL;
 652         }
 653
 654         if (rtc->data->need_accuracy) {
 655                 for (pred_a = 0; pred_a <= pred_a_max; pred_a++) {
 656                         pred_s = (rate / (pred_a + 1)) - 1;
 657
 658                         if (pred_s <= pred_s_max && ((pred_s + 1) * (pred_a + 1)) == rate)
 659                                 break;
 660                 }
 661         } else {
 662                 for (pred_a = pred_a_max; pred_a + 1 > 0; pred_a--) {
 663                         pred_s = (rate / (pred_a + 1)) - 1;
 664
 665                         if (((pred_s + 1) * (pred_a + 1)) == rate)
 666                                 break;
 667                 }
 668         }
 669
 670         /*
 671          * Can't find a 1Hz, so give priority to RTC power consumption
 672          * by choosing the higher possible value for prediv_a
 673          */
 674         if (pred_s > pred_s_max || pred_a > pred_a_max) {
 675                 pred_a = pred_a_max;
 676                 pred_s = (rate / (pred_a + 1)) - 1;
 677
 678                 dev_warn(&pdev->dev, "rtc_ck is %s\n",
 679                          (rate < ((pred_a + 1) * (pred_s + 1))) ?
 680                          "fast" : "slow");
 681         }
 682
 683         cr = readl_relaxed(rtc->base + regs->cr);
 684
 685         prer = readl_relaxed(rtc->base + regs->prer);
 686         prer &= STM32_RTC_PRER_PRED_S | STM32_RTC_PRER_PRED_A;
 687
 688         pred_s = (pred_s << STM32_RTC_PRER_PRED_S_SHIFT) &
 689                  STM32_RTC_PRER_PRED_S;
 690         pred_a = (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) &
 691                  STM32_RTC_PRER_PRED_A;
 692
 693         /* quit if there is nothing to initialize */
 694         if ((cr & STM32_RTC_CR_FMT) == 0 && prer == (pred_s | pred_a))
 695                 return 0;
 696
 697         stm32_rtc_wpr_unlock(rtc);
 698
 699         ret = stm32_rtc_enter_init_mode(rtc);
 700         if (ret) {
 701                 dev_err(&pdev->dev,
 702                         "Can't enter in init mode. Prescaler config failed.\n");
 703                 goto end;
 704         }
 705
 706         writel_relaxed(pred_s, rtc->base + regs->prer);
 707         writel_relaxed(pred_a | pred_s, rtc->base + regs->prer);
 708
 709         /* Force 24h time format */
 710         cr &= ~STM32_RTC_CR_FMT;
 711         writel_relaxed(cr, rtc->base + regs->cr);
 712
 713         stm32_rtc_exit_init_mode(rtc);
 714
 715         ret = stm32_rtc_wait_sync(rtc);
 716 end:
 717         stm32_rtc_wpr_lock(rtc);
 718
 719         return ret;
 720 }
 721
 722 static int stm32_rtc_probe(struct platform_device *pdev)
 723 {
 724         struct stm32_rtc *rtc;
 725         const struct stm32_rtc_registers *regs;
 726         int ret;
 727
 728         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
 729         if (!rtc)
 730                 return -ENOMEM;
 731
 732         rtc->base = devm_platform_ioremap_resource(pdev, 0);
 733         if (IS_ERR(rtc->base))
 734                 return PTR_ERR(rtc->base);
 735
 736         rtc->data = (struct stm32_rtc_data *)
 737                     of_device_get_match_data(&pdev->dev);
 738         regs = &rtc->data->regs;
 739
 740         if (rtc->data->need_dbp) {
 741                 rtc->dbp = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
 742                                                            "st,syscfg");
 743                 if (IS_ERR(rtc->dbp)) {
 744                         dev_err(&pdev->dev, "no st,syscfg\n");
 745                         return PTR_ERR(rtc->dbp);
 746                 }
 747
 748                 ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
 749                                                  1, &rtc->dbp_reg);
 750                 if (ret) {
 751                         dev_err(&pdev->dev, "can't read DBP register offset\n");
 752                         return ret;
 753                 }
 754
 755                 ret = of_property_read_u32_index(pdev->dev.of_node, "st,syscfg",
 756                                                  2, &rtc->dbp_mask);
 757                 if (ret) {
 758                         dev_err(&pdev->dev, "can't read DBP register mask\n");
 759                         return ret;
 760                 }
 761         }
 762
 763         if (!rtc->data->has_pclk) {
 764                 rtc->pclk = NULL;
 765                 rtc->rtc_ck = devm_clk_get(&pdev->dev, NULL);
 766         } else {
 767                 rtc->pclk = devm_clk_get(&pdev->dev, "pclk");
 768                 if (IS_ERR(rtc->pclk))
 769                         return dev_err_probe(&pdev->dev, PTR_ERR(rtc->pclk), "no pclk clock");
 770
 771                 rtc->rtc_ck = devm_clk_get(&pdev->dev, "rtc_ck");
 772         }
 773         if (IS_ERR(rtc->rtc_ck))
 774                 return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_ck), "no rtc_ck clock");
 775
 776         if (rtc->data->has_pclk) {
 777                 ret = clk_prepare_enable(rtc->pclk);
 778                 if (ret)
 779                         return ret;
 780         }
 781
 782         ret = clk_prepare_enable(rtc->rtc_ck);
 783         if (ret)
 784                 goto err_no_rtc_ck;
 785
 786         if (rtc->data->need_dbp)
 787                 regmap_update_bits(rtc->dbp, rtc->dbp_reg,
 788                                    rtc->dbp_mask, rtc->dbp_mask);
 789
 790         /*
 791          * After a system reset, RTC_ISR.INITS flag can be read to check if
 792          * the calendar has been initialized or not. INITS flag is reset by a
 793          * power-on reset (no vbat, no power-supply). It is not reset if
 794          * rtc_ck parent clock has changed (so RTC prescalers need to be
 795          * changed). That's why we cannot rely on this flag to know if RTC
 796          * init has to be done.
 797          */
 798         ret = stm32_rtc_init(pdev, rtc);
 799         if (ret)
 800                 goto err;
 801
 802         rtc->irq_alarm = platform_get_irq(pdev, 0);
 803         if (rtc->irq_alarm <= 0) {
 804                 ret = rtc->irq_alarm;
 805                 goto err;
 806         }
 807
 808         ret = device_init_wakeup(&pdev->dev, true);
 809         if (ret)
 810                 goto err;
 811
 812         ret = dev_pm_set_wake_irq(&pdev->dev, rtc->irq_alarm);
 813         if (ret)
 814                 goto err;
 815
 816         platform_set_drvdata(pdev, rtc);
 817
 818         rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
 819                                                 &stm32_rtc_ops, THIS_MODULE);
 820         if (IS_ERR(rtc->rtc_dev)) {
 821                 ret = PTR_ERR(rtc->rtc_dev);
 822                 dev_err(&pdev->dev, "rtc device registration failed, err=%d\n",
 823                         ret);
 824                 goto err;
 825         }
 826
 827         /* Handle RTC alarm interrupts */
 828         ret = devm_request_threaded_irq(&pdev->dev, rtc->irq_alarm, NULL,
 829                                         stm32_rtc_alarm_irq, IRQF_ONESHOT,
 830                                         pdev->name, rtc);
 831         if (ret) {
 832                 dev_err(&pdev->dev, "IRQ%d (alarm interrupt) already claimed\n",
 833                         rtc->irq_alarm);
 834                 goto err;
 835         }
 836
 837         /*
 838          * If INITS flag is reset (calendar year field set to 0x00), calendar
 839          * must be initialized
 840          */
 841         if (!(readl_relaxed(rtc->base + regs->isr) & STM32_RTC_ISR_INITS))
 842                 dev_warn(&pdev->dev, "Date/Time must be initialized\n");
 843
 844         if (regs->verr != UNDEF_REG) {
 845                 u32 ver = readl_relaxed(rtc->base + regs->verr);
 846
 847                 dev_info(&pdev->dev, "registered rev:%d.%d\n",
 848                          (ver >> STM32_RTC_VERR_MAJREV_SHIFT) & 0xF,
 849                          (ver >> STM32_RTC_VERR_MINREV_SHIFT) & 0xF);
 850         }
 851
 852         return 0;
 853
 854 err:
 855         clk_disable_unprepare(rtc->rtc_ck);
 856 err_no_rtc_ck:
 857         if (rtc->data->has_pclk)
 858                 clk_disable_unprepare(rtc->pclk);
 859
 860         if (rtc->data->need_dbp)
 861                 regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
 862
 863         dev_pm_clear_wake_irq(&pdev->dev);
 864         device_init_wakeup(&pdev->dev, false);
 865
 866         return ret;
 867 }
 868
 869 static void stm32_rtc_remove(struct platform_device *pdev)
 870 {
 871         struct stm32_rtc *rtc = platform_get_drvdata(pdev);
 872         const struct stm32_rtc_registers *regs = &rtc->data->regs;
 873         unsigned int cr;
 874
 875         /* Disable interrupts */
 876         stm32_rtc_wpr_unlock(rtc);
 877         cr = readl_relaxed(rtc->base + regs->cr);
 878         cr &= ~STM32_RTC_CR_ALRAIE;
 879         writel_relaxed(cr, rtc->base + regs->cr);
 880         stm32_rtc_wpr_lock(rtc);
 881
 882         clk_disable_unprepare(rtc->rtc_ck);
 883         if (rtc->data->has_pclk)
 884                 clk_disable_unprepare(rtc->pclk);
 885
 886         /* Enable backup domain write protection if needed */
 887         if (rtc->data->need_dbp)
 888                 regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
 889
 890         dev_pm_clear_wake_irq(&pdev->dev);
 891         device_init_wakeup(&pdev->dev, false);
 892 }
 893
 894 static int stm32_rtc_suspend(struct device *dev)
 895 {
 896         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 897
 898         if (rtc->data->has_pclk)
 899                 clk_disable_unprepare(rtc->pclk);
 900
 901         return 0;
 902 }
 903
 904 static int stm32_rtc_resume(struct device *dev)
 905 {
 906         struct stm32_rtc *rtc = dev_get_drvdata(dev);
 907         int ret = 0;
 908
 909         if (rtc->data->has_pclk) {
 910                 ret = clk_prepare_enable(rtc->pclk);
 911                 if (ret)
 912                         return ret;
 913         }
 914
 915         ret = stm32_rtc_wait_sync(rtc);
 916         if (ret < 0) {
 917                 if (rtc->data->has_pclk)
 918                         clk_disable_unprepare(rtc->pclk);
 919                 return ret;
 920         }
 921
 922         return ret;
 923 }
 924
 925 static const struct dev_pm_ops stm32_rtc_pm_ops = {
 926         NOIRQ_SYSTEM_SLEEP_PM_OPS(stm32_rtc_suspend, stm32_rtc_resume)
 927 };
 928
 929 static struct platform_driver stm32_rtc_driver = {
 930         .probe          = stm32_rtc_probe,
 931         .remove_new     = stm32_rtc_remove,
 932         .driver         = {
 933                 .name   = DRIVER_NAME,
 934                 .pm     = &stm32_rtc_pm_ops,
 935                 .of_match_table = stm32_rtc_of_match,
 936         },
 937 };
 938
 939 module_platform_driver(stm32_rtc_driver);
 940
 941 MODULE_ALIAS("platform:" DRIVER_NAME);
 942 MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
 943 MODULE_DESCRIPTION("STMicroelectronics STM32 Real Time Clock driver");
 944 MODULE_LICENSE("GPL v2");