drivers/rtc/rtc-m41t80.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * I2C client/driver for the ST M41T80 family of i2c rtc chips.
   4  *
   5  * Author: Alexander Bigga <ab@mycable.de>
   6  *
   7  * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
   8  *
   9  * 2006 (c) mycable GmbH
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/bcd.h>
  15 #include <linux/clk-provider.h>
  16 #include <linux/i2c.h>
  17 #include <linux/init.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/of_device.h>
  21 #include <linux/rtc.h>
  22 #include <linux/slab.h>
  23 #include <linux/mutex.h>
  24 #include <linux/string.h>
  25 #ifdef CONFIG_RTC_DRV_M41T80_WDT
  26 #include <linux/fs.h>
  27 #include <linux/ioctl.h>
  28 #include <linux/miscdevice.h>
  29 #include <linux/reboot.h>
  30 #include <linux/watchdog.h>
  31 #endif
  32
  33 #define M41T80_REG_SSEC         0x00
  34 #define M41T80_REG_SEC          0x01
  35 #define M41T80_REG_MIN          0x02
  36 #define M41T80_REG_HOUR         0x03
  37 #define M41T80_REG_WDAY         0x04
  38 #define M41T80_REG_DAY          0x05
  39 #define M41T80_REG_MON          0x06
  40 #define M41T80_REG_YEAR         0x07
  41 #define M41T80_REG_ALARM_MON    0x0a
  42 #define M41T80_REG_ALARM_DAY    0x0b
  43 #define M41T80_REG_ALARM_HOUR   0x0c
  44 #define M41T80_REG_ALARM_MIN    0x0d
  45 #define M41T80_REG_ALARM_SEC    0x0e
  46 #define M41T80_REG_FLAGS        0x0f
  47 #define M41T80_REG_SQW          0x13
  48
  49 #define M41T80_DATETIME_REG_SIZE        (M41T80_REG_YEAR + 1)
  50 #define M41T80_ALARM_REG_SIZE   \
  51         (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
  52
  53 #define M41T80_SQW_MAX_FREQ     32768
  54
  55 #define M41T80_SEC_ST           BIT(7)  /* ST: Stop Bit */
  56 #define M41T80_ALMON_AFE        BIT(7)  /* AFE: AF Enable Bit */
  57 #define M41T80_ALMON_SQWE       BIT(6)  /* SQWE: SQW Enable Bit */
  58 #define M41T80_ALHOUR_HT        BIT(6)  /* HT: Halt Update Bit */
  59 #define M41T80_FLAGS_OF         BIT(2)  /* OF: Oscillator Failure Bit */
  60 #define M41T80_FLAGS_AF         BIT(6)  /* AF: Alarm Flag Bit */
  61 #define M41T80_FLAGS_BATT_LOW   BIT(4)  /* BL: Battery Low Bit */
  62 #define M41T80_WATCHDOG_RB2     BIT(7)  /* RB: Watchdog resolution */
  63 #define M41T80_WATCHDOG_RB1     BIT(1)  /* RB: Watchdog resolution */
  64 #define M41T80_WATCHDOG_RB0     BIT(0)  /* RB: Watchdog resolution */
  65
  66 #define M41T80_FEATURE_HT       BIT(0)  /* Halt feature */
  67 #define M41T80_FEATURE_BL       BIT(1)  /* Battery low indicator */
  68 #define M41T80_FEATURE_SQ       BIT(2)  /* Squarewave feature */
  69 #define M41T80_FEATURE_WD       BIT(3)  /* Extra watchdog resolution */
  70 #define M41T80_FEATURE_SQ_ALT   BIT(4)  /* RSx bits are in reg 4 */
  71
  72 static const struct i2c_device_id m41t80_id[] = {
  73         { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
  74         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  75         { "m41t80", M41T80_FEATURE_SQ },
  76         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  77         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  78         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  79         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  80         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  81         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  82         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  83         { "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
  84         { }
  85 };
  86 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  87
  88 static const struct of_device_id m41t80_of_match[] = {
  89         {
  90                 .compatible = "st,m41t62",
  91                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT)
  92         },
  93         {
  94                 .compatible = "st,m41t65",
  95                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_WD)
  96         },
  97         {
  98                 .compatible = "st,m41t80",
  99                 .data = (void *)(M41T80_FEATURE_SQ)
 100         },
 101         {
 102                 .compatible = "st,m41t81",
 103                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_SQ)
 104         },
 105         {
 106                 .compatible = "st,m41t81s",
 107                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 108         },
 109         {
 110                 .compatible = "st,m41t82",
 111                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 112         },
 113         {
 114                 .compatible = "st,m41t83",
 115                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 116         },
 117         {
 118                 .compatible = "st,m41t84",
 119                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 120         },
 121         {
 122                 .compatible = "st,m41t85",
 123                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 124         },
 125         {
 126                 .compatible = "st,m41t87",
 127                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 128         },
 129         {
 130                 .compatible = "microcrystal,rv4162",
 131                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT)
 132         },
 133         /* DT compatibility only, do not use compatibles below: */
 134         {
 135                 .compatible = "st,rv4162",
 136                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT)
 137         },
 138         {
 139                 .compatible = "rv4162",
 140                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT)
 141         },
 142         { }
 143 };
 144 MODULE_DEVICE_TABLE(of, m41t80_of_match);
 145
 146 struct m41t80_data {
 147         unsigned long features;
 148         struct i2c_client *client;
 149         struct rtc_device *rtc;
 150 #ifdef CONFIG_COMMON_CLK
 151         struct clk_hw sqw;
 152         unsigned long freq;
 153         unsigned int sqwe;
 154 #endif
 155 };
 156
 157 static irqreturn_t m41t80_handle_irq(int irq, void *dev_id)
 158 {
 159         struct i2c_client *client = dev_id;
 160         struct m41t80_data *m41t80 = i2c_get_clientdata(client);
 161         struct mutex *lock = &m41t80->rtc->ops_lock;
 162         unsigned long events = 0;
 163         int flags, flags_afe;
 164
 165         mutex_lock(lock);
 166
 167         flags_afe = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 168         if (flags_afe < 0) {
 169                 mutex_unlock(lock);
 170                 return IRQ_NONE;
 171         }
 172
 173         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 174         if (flags <= 0) {
 175                 mutex_unlock(lock);
 176                 return IRQ_NONE;
 177         }
 178
 179         if (flags & M41T80_FLAGS_AF) {
 180                 flags &= ~M41T80_FLAGS_AF;
 181                 flags_afe &= ~M41T80_ALMON_AFE;
 182                 events |= RTC_AF;
 183         }
 184
 185         if (events) {
 186                 rtc_update_irq(m41t80->rtc, 1, events);
 187                 i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS, flags);
 188                 i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 189                                           flags_afe);
 190         }
 191
 192         mutex_unlock(lock);
 193
 194         return IRQ_HANDLED;
 195 }
 196
 197 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 198 {
 199         struct i2c_client *client = to_i2c_client(dev);
 200         unsigned char buf[8];
 201         int err, flags;
 202
 203         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 204         if (flags < 0)
 205                 return flags;
 206
 207         if (flags & M41T80_FLAGS_OF) {
 208                 dev_err(&client->dev, "Oscillator failure, data is invalid.\n");
 209                 return -EINVAL;
 210         }
 211
 212         err = i2c_smbus_read_i2c_block_data(client, M41T80_REG_SSEC,
 213                                             sizeof(buf), buf);
 214         if (err < 0) {
 215                 dev_err(&client->dev, "Unable to read date\n");
 216                 return err;
 217         }
 218
 219         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 220         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 221         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 222         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 223         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 224         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 225
 226         /* assume 20YY not 19YY, and ignore the Century Bit */
 227         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 228         return 0;
 229 }
 230
 231 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 232 {
 233         struct i2c_client *client = to_i2c_client(dev);
 234         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 235         unsigned char buf[8];
 236         int err, flags;
 237
 238         buf[M41T80_REG_SSEC] = 0;
 239         buf[M41T80_REG_SEC] = bin2bcd(tm->tm_sec);
 240         buf[M41T80_REG_MIN] = bin2bcd(tm->tm_min);
 241         buf[M41T80_REG_HOUR] = bin2bcd(tm->tm_hour);
 242         buf[M41T80_REG_DAY] = bin2bcd(tm->tm_mday);
 243         buf[M41T80_REG_MON] = bin2bcd(tm->tm_mon + 1);
 244         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100);
 245         buf[M41T80_REG_WDAY] = tm->tm_wday;
 246
 247         /* If the square wave output is controlled in the weekday register */
 248         if (clientdata->features & M41T80_FEATURE_SQ_ALT) {
 249                 int val;
 250
 251                 val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY);
 252                 if (val < 0)
 253                         return val;
 254
 255                 buf[M41T80_REG_WDAY] |= (val & 0xf0);
 256         }
 257
 258         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC,
 259                                              sizeof(buf), buf);
 260         if (err < 0) {
 261                 dev_err(&client->dev, "Unable to write to date registers\n");
 262                 return err;
 263         }
 264
 265         /* Clear the OF bit of Flags Register */
 266         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 267         if (flags < 0)
 268                 return flags;
 269
 270         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 271                                         flags & ~M41T80_FLAGS_OF);
 272         if (err < 0) {
 273                 dev_err(&client->dev, "Unable to write flags register\n");
 274                 return err;
 275         }
 276
 277         return err;
 278 }
 279
 280 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 281 {
 282         struct i2c_client *client = to_i2c_client(dev);
 283         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 284         int reg;
 285
 286         if (clientdata->features & M41T80_FEATURE_BL) {
 287                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 288                 if (reg < 0)
 289                         return reg;
 290                 seq_printf(seq, "battery\t\t: %s\n",
 291                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 292         }
 293         return 0;
 294 }
 295
 296 static int m41t80_alarm_irq_enable(struct device *dev, unsigned int enabled)
 297 {
 298         struct i2c_client *client = to_i2c_client(dev);
 299         int flags, retval;
 300
 301         flags = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 302         if (flags < 0)
 303                 return flags;
 304
 305         if (enabled)
 306                 flags |= M41T80_ALMON_AFE;
 307         else
 308                 flags &= ~M41T80_ALMON_AFE;
 309
 310         retval = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, flags);
 311         if (retval < 0) {
 312                 dev_err(dev, "Unable to enable alarm IRQ %d\n", retval);
 313                 return retval;
 314         }
 315         return 0;
 316 }
 317
 318 static int m41t80_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 319 {
 320         struct i2c_client *client = to_i2c_client(dev);
 321         u8 alarmvals[5];
 322         int ret, err;
 323
 324         alarmvals[0] = bin2bcd(alrm->time.tm_mon + 1);
 325         alarmvals[1] = bin2bcd(alrm->time.tm_mday);
 326         alarmvals[2] = bin2bcd(alrm->time.tm_hour);
 327         alarmvals[3] = bin2bcd(alrm->time.tm_min);
 328         alarmvals[4] = bin2bcd(alrm->time.tm_sec);
 329
 330         /* Clear AF and AFE flags */
 331         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 332         if (ret < 0)
 333                 return ret;
 334         err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 335                                         ret & ~(M41T80_ALMON_AFE));
 336         if (err < 0) {
 337                 dev_err(dev, "Unable to clear AFE bit\n");
 338                 return err;
 339         }
 340
 341         /* Keep SQWE bit value */
 342         alarmvals[0] |= (ret & M41T80_ALMON_SQWE);
 343
 344         ret = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 345         if (ret < 0)
 346                 return ret;
 347
 348         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 349                                         ret & ~(M41T80_FLAGS_AF));
 350         if (err < 0) {
 351                 dev_err(dev, "Unable to clear AF bit\n");
 352                 return err;
 353         }
 354
 355         /* Write the alarm */
 356         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_ALARM_MON,
 357                                              5, alarmvals);
 358         if (err)
 359                 return err;
 360
 361         /* Enable the alarm interrupt */
 362         if (alrm->enabled) {
 363                 alarmvals[0] |= M41T80_ALMON_AFE;
 364                 err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 365                                                 alarmvals[0]);
 366                 if (err)
 367                         return err;
 368         }
 369
 370         return 0;
 371 }
 372
 373 static int m41t80_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 374 {
 375         struct i2c_client *client = to_i2c_client(dev);
 376         u8 alarmvals[5];
 377         int flags, ret;
 378
 379         ret = i2c_smbus_read_i2c_block_data(client, M41T80_REG_ALARM_MON,
 380                                             5, alarmvals);
 381         if (ret != 5)
 382                 return ret < 0 ? ret : -EIO;
 383
 384         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 385         if (flags < 0)
 386                 return flags;
 387
 388         alrm->time.tm_sec  = bcd2bin(alarmvals[4] & 0x7f);
 389         alrm->time.tm_min  = bcd2bin(alarmvals[3] & 0x7f);
 390         alrm->time.tm_hour = bcd2bin(alarmvals[2] & 0x3f);
 391         alrm->time.tm_mday = bcd2bin(alarmvals[1] & 0x3f);
 392         alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f) - 1;
 393
 394         alrm->enabled = !!(alarmvals[0] & M41T80_ALMON_AFE);
 395         alrm->pending = (flags & M41T80_FLAGS_AF) && alrm->enabled;
 396
 397         return 0;
 398 }
 399
 400 static struct rtc_class_ops m41t80_rtc_ops = {
 401         .read_time = m41t80_rtc_read_time,
 402         .set_time = m41t80_rtc_set_time,
 403         .proc = m41t80_rtc_proc,
 404 };
 405
 406 #ifdef CONFIG_PM_SLEEP
 407 static int m41t80_suspend(struct device *dev)
 408 {
 409         struct i2c_client *client = to_i2c_client(dev);
 410
 411         if (client->irq >= 0 && device_may_wakeup(dev))
 412                 enable_irq_wake(client->irq);
 413
 414         return 0;
 415 }
 416
 417 static int m41t80_resume(struct device *dev)
 418 {
 419         struct i2c_client *client = to_i2c_client(dev);
 420
 421         if (client->irq >= 0 && device_may_wakeup(dev))
 422                 disable_irq_wake(client->irq);
 423
 424         return 0;
 425 }
 426 #endif
 427
 428 static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
 429
 430 #ifdef CONFIG_COMMON_CLK
 431 #define sqw_to_m41t80_data(_hw) container_of(_hw, struct m41t80_data, sqw)
 432
 433 static unsigned long m41t80_decode_freq(int setting)
 434 {
 435         return (setting == 0) ? 0 : (setting == 1) ? M41T80_SQW_MAX_FREQ :
 436                 M41T80_SQW_MAX_FREQ >> setting;
 437 }
 438
 439 static unsigned long m41t80_get_freq(struct m41t80_data *m41t80)
 440 {
 441         struct i2c_client *client = m41t80->client;
 442         int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 443                 M41T80_REG_WDAY : M41T80_REG_SQW;
 444         int ret = i2c_smbus_read_byte_data(client, reg_sqw);
 445
 446         if (ret < 0)
 447                 return 0;
 448         return m41t80_decode_freq(ret >> 4);
 449 }
 450
 451 static unsigned long m41t80_sqw_recalc_rate(struct clk_hw *hw,
 452                                             unsigned long parent_rate)
 453 {
 454         return sqw_to_m41t80_data(hw)->freq;
 455 }
 456
 457 static long m41t80_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
 458                                   unsigned long *prate)
 459 {
 460         if (rate >= M41T80_SQW_MAX_FREQ)
 461                 return M41T80_SQW_MAX_FREQ;
 462         if (rate >= M41T80_SQW_MAX_FREQ / 4)
 463                 return M41T80_SQW_MAX_FREQ / 4;
 464         if (!rate)
 465                 return 0;
 466         return 1 << ilog2(rate);
 467 }
 468
 469 static int m41t80_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
 470                                unsigned long parent_rate)
 471 {
 472         struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 473         struct i2c_client *client = m41t80->client;
 474         int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 475                 M41T80_REG_WDAY : M41T80_REG_SQW;
 476         int reg, ret, val = 0;
 477
 478         if (rate >= M41T80_SQW_MAX_FREQ)
 479                 val = 1;
 480         else if (rate >= M41T80_SQW_MAX_FREQ / 4)
 481                 val = 2;
 482         else if (rate)
 483                 val = 15 - ilog2(rate);
 484
 485         reg = i2c_smbus_read_byte_data(client, reg_sqw);
 486         if (reg < 0)
 487                 return reg;
 488
 489         reg = (reg & 0x0f) | (val << 4);
 490
 491         ret = i2c_smbus_write_byte_data(client, reg_sqw, reg);
 492         if (!ret)
 493                 m41t80->freq = m41t80_decode_freq(val);
 494         return ret;
 495 }
 496
 497 static int m41t80_sqw_control(struct clk_hw *hw, bool enable)
 498 {
 499         struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 500         struct i2c_client *client = m41t80->client;
 501         int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 502
 503         if (ret < 0)
 504                 return ret;
 505
 506         if (enable)
 507                 ret |= M41T80_ALMON_SQWE;
 508         else
 509                 ret &= ~M41T80_ALMON_SQWE;
 510
 511         ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret);
 512         if (!ret)
 513                 m41t80->sqwe = enable;
 514         return ret;
 515 }
 516
 517 static int m41t80_sqw_prepare(struct clk_hw *hw)
 518 {
 519         return m41t80_sqw_control(hw, 1);
 520 }
 521
 522 static void m41t80_sqw_unprepare(struct clk_hw *hw)
 523 {
 524         m41t80_sqw_control(hw, 0);
 525 }
 526
 527 static int m41t80_sqw_is_prepared(struct clk_hw *hw)
 528 {
 529         return sqw_to_m41t80_data(hw)->sqwe;
 530 }
 531
 532 static const struct clk_ops m41t80_sqw_ops = {
 533         .prepare = m41t80_sqw_prepare,
 534         .unprepare = m41t80_sqw_unprepare,
 535         .is_prepared = m41t80_sqw_is_prepared,
 536         .recalc_rate = m41t80_sqw_recalc_rate,
 537         .round_rate = m41t80_sqw_round_rate,
 538         .set_rate = m41t80_sqw_set_rate,
 539 };
 540
 541 static struct clk *m41t80_sqw_register_clk(struct m41t80_data *m41t80)
 542 {
 543         struct i2c_client *client = m41t80->client;
 544         struct device_node *node = client->dev.of_node;
 545         struct clk *clk;
 546         struct clk_init_data init;
 547         int ret;
 548
 549         /* First disable the clock */
 550         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 551         if (ret < 0)
 552                 return ERR_PTR(ret);
 553         ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 554                                         ret & ~(M41T80_ALMON_SQWE));
 555         if (ret < 0)
 556                 return ERR_PTR(ret);
 557
 558         init.name = "m41t80-sqw";
 559         init.ops = &m41t80_sqw_ops;
 560         init.flags = 0;
 561         init.parent_names = NULL;
 562         init.num_parents = 0;
 563         m41t80->sqw.init = &init;
 564         m41t80->freq = m41t80_get_freq(m41t80);
 565
 566         /* optional override of the clockname */
 567         of_property_read_string(node, "clock-output-names", &init.name);
 568
 569         /* register the clock */
 570         clk = clk_register(&client->dev, &m41t80->sqw);
 571         if (!IS_ERR(clk))
 572                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 573
 574         return clk;
 575 }
 576 #endif
 577
 578 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 579 /*
 580  *****************************************************************************
 581  *
 582  * Watchdog Driver
 583  *
 584  *****************************************************************************
 585  */
 586 static DEFINE_MUTEX(m41t80_rtc_mutex);
 587 static struct i2c_client *save_client;
 588
 589 /* Default margin */
 590 #define WD_TIMO 60              /* 1..31 seconds */
 591
 592 static int wdt_margin = WD_TIMO;
 593 module_param(wdt_margin, int, 0);
 594 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 595
 596 static unsigned long wdt_is_open;
 597 static int boot_flag;
 598
 599 /**
 600  *      wdt_ping:
 601  *
 602  *      Reload counter one with the watchdog timeout. We don't bother reloading
 603  *      the cascade counter.
 604  */
 605 static void wdt_ping(void)
 606 {
 607         unsigned char i2c_data[2];
 608         struct i2c_msg msgs1[1] = {
 609                 {
 610                         .addr   = save_client->addr,
 611                         .flags  = 0,
 612                         .len    = 2,
 613                         .buf    = i2c_data,
 614                 },
 615         };
 616         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 617
 618         i2c_data[0] = 0x09;             /* watchdog register */
 619
 620         if (wdt_margin > 31)
 621                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 622         else
 623                 /*
 624                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 625                  */
 626                 i2c_data[1] = wdt_margin << 2 | 0x82;
 627
 628         /*
 629          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 630          * that would be an invalid resolution.
 631          */
 632         if (clientdata->features & M41T80_FEATURE_WD)
 633                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 634
 635         i2c_transfer(save_client->adapter, msgs1, 1);
 636 }
 637
 638 /**
 639  *      wdt_disable:
 640  *
 641  *      disables watchdog.
 642  */
 643 static void wdt_disable(void)
 644 {
 645         unsigned char i2c_data[2], i2c_buf[0x10];
 646         struct i2c_msg msgs0[2] = {
 647                 {
 648                         .addr   = save_client->addr,
 649                         .flags  = 0,
 650                         .len    = 1,
 651                         .buf    = i2c_data,
 652                 },
 653                 {
 654                         .addr   = save_client->addr,
 655                         .flags  = I2C_M_RD,
 656                         .len    = 1,
 657                         .buf    = i2c_buf,
 658                 },
 659         };
 660         struct i2c_msg msgs1[1] = {
 661                 {
 662                         .addr   = save_client->addr,
 663                         .flags  = 0,
 664                         .len    = 2,
 665                         .buf    = i2c_data,
 666                 },
 667         };
 668
 669         i2c_data[0] = 0x09;
 670         i2c_transfer(save_client->adapter, msgs0, 2);
 671
 672         i2c_data[0] = 0x09;
 673         i2c_data[1] = 0x00;
 674         i2c_transfer(save_client->adapter, msgs1, 1);
 675 }
 676
 677 /**
 678  *      wdt_write:
 679  *      @file: file handle to the watchdog
 680  *      @buf: buffer to write (unused as data does not matter here
 681  *      @count: count of bytes
 682  *      @ppos: pointer to the position to write. No seeks allowed
 683  *
 684  *      A write to a watchdog device is defined as a keepalive signal. Any
 685  *      write of data will do, as we we don't define content meaning.
 686  */
 687 static ssize_t wdt_write(struct file *file, const char __user *buf,
 688                          size_t count, loff_t *ppos)
 689 {
 690         if (count) {
 691                 wdt_ping();
 692                 return 1;
 693         }
 694         return 0;
 695 }
 696
 697 static ssize_t wdt_read(struct file *file, char __user *buf,
 698                         size_t count, loff_t *ppos)
 699 {
 700         return 0;
 701 }
 702
 703 /**
 704  *      wdt_ioctl:
 705  *      @file: file handle to the device
 706  *      @cmd: watchdog command
 707  *      @arg: argument pointer
 708  *
 709  *      The watchdog API defines a common set of functions for all watchdogs
 710  *      according to their available features. We only actually usefully support
 711  *      querying capabilities and current status.
 712  */
 713 static int wdt_ioctl(struct file *file, unsigned int cmd,
 714                      unsigned long arg)
 715 {
 716         int new_margin, rv;
 717         static struct watchdog_info ident = {
 718                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 719                         WDIOF_SETTIMEOUT,
 720                 .firmware_version = 1,
 721                 .identity = "M41T80 WTD"
 722         };
 723
 724         switch (cmd) {
 725         case WDIOC_GETSUPPORT:
 726                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 727                                     sizeof(ident)) ? -EFAULT : 0;
 728
 729         case WDIOC_GETSTATUS:
 730         case WDIOC_GETBOOTSTATUS:
 731                 return put_user(boot_flag, (int __user *)arg);
 732         case WDIOC_KEEPALIVE:
 733                 wdt_ping();
 734                 return 0;
 735         case WDIOC_SETTIMEOUT:
 736                 if (get_user(new_margin, (int __user *)arg))
 737                         return -EFAULT;
 738                 /* Arbitrary, can't find the card's limits */
 739                 if (new_margin < 1 || new_margin > 124)
 740                         return -EINVAL;
 741                 wdt_margin = new_margin;
 742                 wdt_ping();
 743                 fallthrough;
 744         case WDIOC_GETTIMEOUT:
 745                 return put_user(wdt_margin, (int __user *)arg);
 746
 747         case WDIOC_SETOPTIONS:
 748                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 749                         return -EFAULT;
 750
 751                 if (rv & WDIOS_DISABLECARD) {
 752                         pr_info("disable watchdog\n");
 753                         wdt_disable();
 754                 }
 755
 756                 if (rv & WDIOS_ENABLECARD) {
 757                         pr_info("enable watchdog\n");
 758                         wdt_ping();
 759                 }
 760
 761                 return -EINVAL;
 762         }
 763         return -ENOTTY;
 764 }
 765
 766 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 767                                unsigned long arg)
 768 {
 769         int ret;
 770
 771         mutex_lock(&m41t80_rtc_mutex);
 772         ret = wdt_ioctl(file, cmd, arg);
 773         mutex_unlock(&m41t80_rtc_mutex);
 774
 775         return ret;
 776 }
 777
 778 /**
 779  *      wdt_open:
 780  *      @inode: inode of device
 781  *      @file: file handle to device
 782  *
 783  */
 784 static int wdt_open(struct inode *inode, struct file *file)
 785 {
 786         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 787                 mutex_lock(&m41t80_rtc_mutex);
 788                 if (test_and_set_bit(0, &wdt_is_open)) {
 789                         mutex_unlock(&m41t80_rtc_mutex);
 790                         return -EBUSY;
 791                 }
 792                 /*
 793                  *      Activate
 794                  */
 795                 wdt_is_open = 1;
 796                 mutex_unlock(&m41t80_rtc_mutex);
 797                 return stream_open(inode, file);
 798         }
 799         return -ENODEV;
 800 }
 801
 802 /**
 803  *      wdt_close:
 804  *      @inode: inode to board
 805  *      @file: file handle to board
 806  *
 807  */
 808 static int wdt_release(struct inode *inode, struct file *file)
 809 {
 810         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 811                 clear_bit(0, &wdt_is_open);
 812         return 0;
 813 }
 814
 815 /**
 816  *      notify_sys:
 817  *      @this: our notifier block
 818  *      @code: the event being reported
 819  *      @unused: unused
 820  *
 821  *      Our notifier is called on system shutdowns. We want to turn the card
 822  *      off at reboot otherwise the machine will reboot again during memory
 823  *      test or worse yet during the following fsck. This would suck, in fact
 824  *      trust me - if it happens it does suck.
 825  */
 826 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 827                           void *unused)
 828 {
 829         if (code == SYS_DOWN || code == SYS_HALT)
 830                 /* Disable Watchdog */
 831                 wdt_disable();
 832         return NOTIFY_DONE;
 833 }
 834
 835 static const struct file_operations wdt_fops = {
 836         .owner  = THIS_MODULE,
 837         .read   = wdt_read,
 838         .unlocked_ioctl = wdt_unlocked_ioctl,
 839         .compat_ioctl = compat_ptr_ioctl,
 840         .write  = wdt_write,
 841         .open   = wdt_open,
 842         .release = wdt_release,
 843         .llseek = no_llseek,
 844 };
 845
 846 static struct miscdevice wdt_dev = {
 847         .minor = WATCHDOG_MINOR,
 848         .name = "watchdog",
 849         .fops = &wdt_fops,
 850 };
 851
 852 /*
 853  *      The WDT card needs to learn about soft shutdowns in order to
 854  *      turn the timebomb registers off.
 855  */
 856 static struct notifier_block wdt_notifier = {
 857         .notifier_call = wdt_notify_sys,
 858 };
 859 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 860
 861 /*
 862  *****************************************************************************
 863  *
 864  *      Driver Interface
 865  *
 866  *****************************************************************************
 867  */
 868
 869 static int m41t80_probe(struct i2c_client *client,
 870                         const struct i2c_device_id *id)
 871 {
 872         struct i2c_adapter *adapter = client->adapter;
 873         int rc = 0;
 874         struct rtc_time tm;
 875         struct m41t80_data *m41t80_data = NULL;
 876         bool wakeup_source = false;
 877
 878         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK |
 879                                      I2C_FUNC_SMBUS_BYTE_DATA)) {
 880                 dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
 881                 return -ENODEV;
 882         }
 883
 884         m41t80_data = devm_kzalloc(&client->dev, sizeof(*m41t80_data),
 885                                    GFP_KERNEL);
 886         if (!m41t80_data)
 887                 return -ENOMEM;
 888
 889         m41t80_data->client = client;
 890         if (client->dev.of_node)
 891                 m41t80_data->features = (unsigned long)
 892                         of_device_get_match_data(&client->dev);
 893         else
 894                 m41t80_data->features = id->driver_data;
 895         i2c_set_clientdata(client, m41t80_data);
 896
 897         m41t80_data->rtc =  devm_rtc_allocate_device(&client->dev);
 898         if (IS_ERR(m41t80_data->rtc))
 899                 return PTR_ERR(m41t80_data->rtc);
 900
 901 #ifdef CONFIG_OF
 902         wakeup_source = of_property_read_bool(client->dev.of_node,
 903                                               "wakeup-source");
 904 #endif
 905         if (client->irq > 0) {
 906                 rc = devm_request_threaded_irq(&client->dev, client->irq,
 907                                                NULL, m41t80_handle_irq,
 908                                                IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 909                                                "m41t80", client);
 910                 if (rc) {
 911                         dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
 912                         client->irq = 0;
 913                         wakeup_source = false;
 914                 }
 915         }
 916         if (client->irq > 0 || wakeup_source) {
 917                 m41t80_rtc_ops.read_alarm = m41t80_read_alarm;
 918                 m41t80_rtc_ops.set_alarm = m41t80_set_alarm;
 919                 m41t80_rtc_ops.alarm_irq_enable = m41t80_alarm_irq_enable;
 920                 /* Enable the wakealarm */
 921                 device_init_wakeup(&client->dev, true);
 922         }
 923
 924         m41t80_data->rtc->ops = &m41t80_rtc_ops;
 925         m41t80_data->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 926         m41t80_data->rtc->range_max = RTC_TIMESTAMP_END_2099;
 927
 928         if (client->irq <= 0) {
 929                 /* We cannot support UIE mode if we do not have an IRQ line */
 930                 m41t80_data->rtc->uie_unsupported = 1;
 931         }
 932
 933         /* Make sure HT (Halt Update) bit is cleared */
 934         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 935
 936         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 937                 if (m41t80_data->features & M41T80_FEATURE_HT) {
 938                         m41t80_rtc_read_time(&client->dev, &tm);
 939                         dev_info(&client->dev, "HT bit was set!\n");
 940                         dev_info(&client->dev, "Power Down at %ptR\n", &tm);
 941                 }
 942                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 943                                                rc & ~M41T80_ALHOUR_HT);
 944         }
 945
 946         if (rc < 0) {
 947                 dev_err(&client->dev, "Can't clear HT bit\n");
 948                 return rc;
 949         }
 950
 951         /* Make sure ST (stop) bit is cleared */
 952         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 953
 954         if (rc >= 0 && rc & M41T80_SEC_ST)
 955                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 956                                                rc & ~M41T80_SEC_ST);
 957         if (rc < 0) {
 958                 dev_err(&client->dev, "Can't clear ST bit\n");
 959                 return rc;
 960         }
 961
 962 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 963         if (m41t80_data->features & M41T80_FEATURE_HT) {
 964                 save_client = client;
 965                 rc = misc_register(&wdt_dev);
 966                 if (rc)
 967                         return rc;
 968                 rc = register_reboot_notifier(&wdt_notifier);
 969                 if (rc) {
 970                         misc_deregister(&wdt_dev);
 971                         return rc;
 972                 }
 973         }
 974 #endif
 975 #ifdef CONFIG_COMMON_CLK
 976         if (m41t80_data->features & M41T80_FEATURE_SQ)
 977                 m41t80_sqw_register_clk(m41t80_data);
 978 #endif
 979
 980         rc = devm_rtc_register_device(m41t80_data->rtc);
 981         if (rc)
 982                 return rc;
 983
 984         return 0;
 985 }
 986
 987 static int m41t80_remove(struct i2c_client *client)
 988 {
 989 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 990         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 991
 992         if (clientdata->features & M41T80_FEATURE_HT) {
 993                 misc_deregister(&wdt_dev);
 994                 unregister_reboot_notifier(&wdt_notifier);
 995         }
 996 #endif
 997
 998         return 0;
 999 }
1000
1001 static struct i2c_driver m41t80_driver = {
1002         .driver = {
1003                 .name = "rtc-m41t80",
1004                 .of_match_table = of_match_ptr(m41t80_of_match),
1005                 .pm = &m41t80_pm,
1006         },
1007         .probe = m41t80_probe,
1008         .remove = m41t80_remove,
1009         .id_table = m41t80_id,
1010 };
1011
1012 module_i2c_driver(m41t80_driver);
1013
1014 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
1015 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
1016 MODULE_LICENSE("GPL");