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         if (tm->tm_year < 100 || tm->tm_year > 199)
 239                 return -EINVAL;
 240
 241         buf[M41T80_REG_SSEC] = 0;
 242         buf[M41T80_REG_SEC] = bin2bcd(tm->tm_sec);
 243         buf[M41T80_REG_MIN] = bin2bcd(tm->tm_min);
 244         buf[M41T80_REG_HOUR] = bin2bcd(tm->tm_hour);
 245         buf[M41T80_REG_DAY] = bin2bcd(tm->tm_mday);
 246         buf[M41T80_REG_MON] = bin2bcd(tm->tm_mon + 1);
 247         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100);
 248         buf[M41T80_REG_WDAY] = tm->tm_wday;
 249
 250         /* If the square wave output is controlled in the weekday register */
 251         if (clientdata->features & M41T80_FEATURE_SQ_ALT) {
 252                 int val;
 253
 254                 val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY);
 255                 if (val < 0)
 256                         return val;
 257
 258                 buf[M41T80_REG_WDAY] |= (val & 0xf0);
 259         }
 260
 261         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC,
 262                                              sizeof(buf), buf);
 263         if (err < 0) {
 264                 dev_err(&client->dev, "Unable to write to date registers\n");
 265                 return err;
 266         }
 267
 268         /* Clear the OF bit of Flags Register */
 269         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 270         if (flags < 0)
 271                 return flags;
 272
 273         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 274                                         flags & ~M41T80_FLAGS_OF);
 275         if (err < 0) {
 276                 dev_err(&client->dev, "Unable to write flags register\n");
 277                 return err;
 278         }
 279
 280         return err;
 281 }
 282
 283 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 284 {
 285         struct i2c_client *client = to_i2c_client(dev);
 286         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 287         int reg;
 288
 289         if (clientdata->features & M41T80_FEATURE_BL) {
 290                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 291                 if (reg < 0)
 292                         return reg;
 293                 seq_printf(seq, "battery\t\t: %s\n",
 294                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 295         }
 296         return 0;
 297 }
 298
 299 static int m41t80_alarm_irq_enable(struct device *dev, unsigned int enabled)
 300 {
 301         struct i2c_client *client = to_i2c_client(dev);
 302         int flags, retval;
 303
 304         flags = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 305         if (flags < 0)
 306                 return flags;
 307
 308         if (enabled)
 309                 flags |= M41T80_ALMON_AFE;
 310         else
 311                 flags &= ~M41T80_ALMON_AFE;
 312
 313         retval = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, flags);
 314         if (retval < 0) {
 315                 dev_err(dev, "Unable to enable alarm IRQ %d\n", retval);
 316                 return retval;
 317         }
 318         return 0;
 319 }
 320
 321 static int m41t80_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 322 {
 323         struct i2c_client *client = to_i2c_client(dev);
 324         u8 alarmvals[5];
 325         int ret, err;
 326
 327         alarmvals[0] = bin2bcd(alrm->time.tm_mon + 1);
 328         alarmvals[1] = bin2bcd(alrm->time.tm_mday);
 329         alarmvals[2] = bin2bcd(alrm->time.tm_hour);
 330         alarmvals[3] = bin2bcd(alrm->time.tm_min);
 331         alarmvals[4] = bin2bcd(alrm->time.tm_sec);
 332
 333         /* Clear AF and AFE flags */
 334         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 335         if (ret < 0)
 336                 return ret;
 337         err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 338                                         ret & ~(M41T80_ALMON_AFE));
 339         if (err < 0) {
 340                 dev_err(dev, "Unable to clear AFE bit\n");
 341                 return err;
 342         }
 343
 344         /* Keep SQWE bit value */
 345         alarmvals[0] |= (ret & M41T80_ALMON_SQWE);
 346
 347         ret = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 348         if (ret < 0)
 349                 return ret;
 350
 351         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 352                                         ret & ~(M41T80_FLAGS_AF));
 353         if (err < 0) {
 354                 dev_err(dev, "Unable to clear AF bit\n");
 355                 return err;
 356         }
 357
 358         /* Write the alarm */
 359         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_ALARM_MON,
 360                                              5, alarmvals);
 361         if (err)
 362                 return err;
 363
 364         /* Enable the alarm interrupt */
 365         if (alrm->enabled) {
 366                 alarmvals[0] |= M41T80_ALMON_AFE;
 367                 err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 368                                                 alarmvals[0]);
 369                 if (err)
 370                         return err;
 371         }
 372
 373         return 0;
 374 }
 375
 376 static int m41t80_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 377 {
 378         struct i2c_client *client = to_i2c_client(dev);
 379         u8 alarmvals[5];
 380         int flags, ret;
 381
 382         ret = i2c_smbus_read_i2c_block_data(client, M41T80_REG_ALARM_MON,
 383                                             5, alarmvals);
 384         if (ret != 5)
 385                 return ret < 0 ? ret : -EIO;
 386
 387         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 388         if (flags < 0)
 389                 return flags;
 390
 391         alrm->time.tm_sec  = bcd2bin(alarmvals[4] & 0x7f);
 392         alrm->time.tm_min  = bcd2bin(alarmvals[3] & 0x7f);
 393         alrm->time.tm_hour = bcd2bin(alarmvals[2] & 0x3f);
 394         alrm->time.tm_mday = bcd2bin(alarmvals[1] & 0x3f);
 395         alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f) - 1;
 396
 397         alrm->enabled = !!(alarmvals[0] & M41T80_ALMON_AFE);
 398         alrm->pending = (flags & M41T80_FLAGS_AF) && alrm->enabled;
 399
 400         return 0;
 401 }
 402
 403 static struct rtc_class_ops m41t80_rtc_ops = {
 404         .read_time = m41t80_rtc_read_time,
 405         .set_time = m41t80_rtc_set_time,
 406         .proc = m41t80_rtc_proc,
 407 };
 408
 409 #ifdef CONFIG_PM_SLEEP
 410 static int m41t80_suspend(struct device *dev)
 411 {
 412         struct i2c_client *client = to_i2c_client(dev);
 413
 414         if (client->irq >= 0 && device_may_wakeup(dev))
 415                 enable_irq_wake(client->irq);
 416
 417         return 0;
 418 }
 419
 420 static int m41t80_resume(struct device *dev)
 421 {
 422         struct i2c_client *client = to_i2c_client(dev);
 423
 424         if (client->irq >= 0 && device_may_wakeup(dev))
 425                 disable_irq_wake(client->irq);
 426
 427         return 0;
 428 }
 429 #endif
 430
 431 static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
 432
 433 #ifdef CONFIG_COMMON_CLK
 434 #define sqw_to_m41t80_data(_hw) container_of(_hw, struct m41t80_data, sqw)
 435
 436 static unsigned long m41t80_decode_freq(int setting)
 437 {
 438         return (setting == 0) ? 0 : (setting == 1) ? M41T80_SQW_MAX_FREQ :
 439                 M41T80_SQW_MAX_FREQ >> setting;
 440 }
 441
 442 static unsigned long m41t80_get_freq(struct m41t80_data *m41t80)
 443 {
 444         struct i2c_client *client = m41t80->client;
 445         int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 446                 M41T80_REG_WDAY : M41T80_REG_SQW;
 447         int ret = i2c_smbus_read_byte_data(client, reg_sqw);
 448
 449         if (ret < 0)
 450                 return 0;
 451         return m41t80_decode_freq(ret >> 4);
 452 }
 453
 454 static unsigned long m41t80_sqw_recalc_rate(struct clk_hw *hw,
 455                                             unsigned long parent_rate)
 456 {
 457         return sqw_to_m41t80_data(hw)->freq;
 458 }
 459
 460 static long m41t80_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
 461                                   unsigned long *prate)
 462 {
 463         if (rate >= M41T80_SQW_MAX_FREQ)
 464                 return M41T80_SQW_MAX_FREQ;
 465         if (rate >= M41T80_SQW_MAX_FREQ / 4)
 466                 return M41T80_SQW_MAX_FREQ / 4;
 467         if (!rate)
 468                 return 0;
 469         return 1 << ilog2(rate);
 470 }
 471
 472 static int m41t80_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
 473                                unsigned long parent_rate)
 474 {
 475         struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 476         struct i2c_client *client = m41t80->client;
 477         int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 478                 M41T80_REG_WDAY : M41T80_REG_SQW;
 479         int reg, ret, val = 0;
 480
 481         if (rate >= M41T80_SQW_MAX_FREQ)
 482                 val = 1;
 483         else if (rate >= M41T80_SQW_MAX_FREQ / 4)
 484                 val = 2;
 485         else if (rate)
 486                 val = 15 - ilog2(rate);
 487
 488         reg = i2c_smbus_read_byte_data(client, reg_sqw);
 489         if (reg < 0)
 490                 return reg;
 491
 492         reg = (reg & 0x0f) | (val << 4);
 493
 494         ret = i2c_smbus_write_byte_data(client, reg_sqw, reg);
 495         if (!ret)
 496                 m41t80->freq = m41t80_decode_freq(val);
 497         return ret;
 498 }
 499
 500 static int m41t80_sqw_control(struct clk_hw *hw, bool enable)
 501 {
 502         struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 503         struct i2c_client *client = m41t80->client;
 504         int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 505
 506         if (ret < 0)
 507                 return ret;
 508
 509         if (enable)
 510                 ret |= M41T80_ALMON_SQWE;
 511         else
 512                 ret &= ~M41T80_ALMON_SQWE;
 513
 514         ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret);
 515         if (!ret)
 516                 m41t80->sqwe = enable;
 517         return ret;
 518 }
 519
 520 static int m41t80_sqw_prepare(struct clk_hw *hw)
 521 {
 522         return m41t80_sqw_control(hw, 1);
 523 }
 524
 525 static void m41t80_sqw_unprepare(struct clk_hw *hw)
 526 {
 527         m41t80_sqw_control(hw, 0);
 528 }
 529
 530 static int m41t80_sqw_is_prepared(struct clk_hw *hw)
 531 {
 532         return sqw_to_m41t80_data(hw)->sqwe;
 533 }
 534
 535 static const struct clk_ops m41t80_sqw_ops = {
 536         .prepare = m41t80_sqw_prepare,
 537         .unprepare = m41t80_sqw_unprepare,
 538         .is_prepared = m41t80_sqw_is_prepared,
 539         .recalc_rate = m41t80_sqw_recalc_rate,
 540         .round_rate = m41t80_sqw_round_rate,
 541         .set_rate = m41t80_sqw_set_rate,
 542 };
 543
 544 static struct clk *m41t80_sqw_register_clk(struct m41t80_data *m41t80)
 545 {
 546         struct i2c_client *client = m41t80->client;
 547         struct device_node *node = client->dev.of_node;
 548         struct clk *clk;
 549         struct clk_init_data init;
 550         int ret;
 551
 552         /* First disable the clock */
 553         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 554         if (ret < 0)
 555                 return ERR_PTR(ret);
 556         ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 557                                         ret & ~(M41T80_ALMON_SQWE));
 558         if (ret < 0)
 559                 return ERR_PTR(ret);
 560
 561         init.name = "m41t80-sqw";
 562         init.ops = &m41t80_sqw_ops;
 563         init.flags = 0;
 564         init.parent_names = NULL;
 565         init.num_parents = 0;
 566         m41t80->sqw.init = &init;
 567         m41t80->freq = m41t80_get_freq(m41t80);
 568
 569         /* optional override of the clockname */
 570         of_property_read_string(node, "clock-output-names", &init.name);
 571
 572         /* register the clock */
 573         clk = clk_register(&client->dev, &m41t80->sqw);
 574         if (!IS_ERR(clk))
 575                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 576
 577         return clk;
 578 }
 579 #endif
 580
 581 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 582 /*
 583  *****************************************************************************
 584  *
 585  * Watchdog Driver
 586  *
 587  *****************************************************************************
 588  */
 589 static DEFINE_MUTEX(m41t80_rtc_mutex);
 590 static struct i2c_client *save_client;
 591
 592 /* Default margin */
 593 #define WD_TIMO 60              /* 1..31 seconds */
 594
 595 static int wdt_margin = WD_TIMO;
 596 module_param(wdt_margin, int, 0);
 597 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 598
 599 static unsigned long wdt_is_open;
 600 static int boot_flag;
 601
 602 /**
 603  *      wdt_ping:
 604  *
 605  *      Reload counter one with the watchdog timeout. We don't bother reloading
 606  *      the cascade counter.
 607  */
 608 static void wdt_ping(void)
 609 {
 610         unsigned char i2c_data[2];
 611         struct i2c_msg msgs1[1] = {
 612                 {
 613                         .addr   = save_client->addr,
 614                         .flags  = 0,
 615                         .len    = 2,
 616                         .buf    = i2c_data,
 617                 },
 618         };
 619         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 620
 621         i2c_data[0] = 0x09;             /* watchdog register */
 622
 623         if (wdt_margin > 31)
 624                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 625         else
 626                 /*
 627                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 628                  */
 629                 i2c_data[1] = wdt_margin << 2 | 0x82;
 630
 631         /*
 632          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 633          * that would be an invalid resolution.
 634          */
 635         if (clientdata->features & M41T80_FEATURE_WD)
 636                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 637
 638         i2c_transfer(save_client->adapter, msgs1, 1);
 639 }
 640
 641 /**
 642  *      wdt_disable:
 643  *
 644  *      disables watchdog.
 645  */
 646 static void wdt_disable(void)
 647 {
 648         unsigned char i2c_data[2], i2c_buf[0x10];
 649         struct i2c_msg msgs0[2] = {
 650                 {
 651                         .addr   = save_client->addr,
 652                         .flags  = 0,
 653                         .len    = 1,
 654                         .buf    = i2c_data,
 655                 },
 656                 {
 657                         .addr   = save_client->addr,
 658                         .flags  = I2C_M_RD,
 659                         .len    = 1,
 660                         .buf    = i2c_buf,
 661                 },
 662         };
 663         struct i2c_msg msgs1[1] = {
 664                 {
 665                         .addr   = save_client->addr,
 666                         .flags  = 0,
 667                         .len    = 2,
 668                         .buf    = i2c_data,
 669                 },
 670         };
 671
 672         i2c_data[0] = 0x09;
 673         i2c_transfer(save_client->adapter, msgs0, 2);
 674
 675         i2c_data[0] = 0x09;
 676         i2c_data[1] = 0x00;
 677         i2c_transfer(save_client->adapter, msgs1, 1);
 678 }
 679
 680 /**
 681  *      wdt_write:
 682  *      @file: file handle to the watchdog
 683  *      @buf: buffer to write (unused as data does not matter here
 684  *      @count: count of bytes
 685  *      @ppos: pointer to the position to write. No seeks allowed
 686  *
 687  *      A write to a watchdog device is defined as a keepalive signal. Any
 688  *      write of data will do, as we we don't define content meaning.
 689  */
 690 static ssize_t wdt_write(struct file *file, const char __user *buf,
 691                          size_t count, loff_t *ppos)
 692 {
 693         if (count) {
 694                 wdt_ping();
 695                 return 1;
 696         }
 697         return 0;
 698 }
 699
 700 static ssize_t wdt_read(struct file *file, char __user *buf,
 701                         size_t count, loff_t *ppos)
 702 {
 703         return 0;
 704 }
 705
 706 /**
 707  *      wdt_ioctl:
 708  *      @inode: inode of the device
 709  *      @file: file handle to the device
 710  *      @cmd: watchdog command
 711  *      @arg: argument pointer
 712  *
 713  *      The watchdog API defines a common set of functions for all watchdogs
 714  *      according to their available features. We only actually usefully support
 715  *      querying capabilities and current status.
 716  */
 717 static int wdt_ioctl(struct file *file, unsigned int cmd,
 718                      unsigned long arg)
 719 {
 720         int new_margin, rv;
 721         static struct watchdog_info ident = {
 722                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 723                         WDIOF_SETTIMEOUT,
 724                 .firmware_version = 1,
 725                 .identity = "M41T80 WTD"
 726         };
 727
 728         switch (cmd) {
 729         case WDIOC_GETSUPPORT:
 730                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 731                                     sizeof(ident)) ? -EFAULT : 0;
 732
 733         case WDIOC_GETSTATUS:
 734         case WDIOC_GETBOOTSTATUS:
 735                 return put_user(boot_flag, (int __user *)arg);
 736         case WDIOC_KEEPALIVE:
 737                 wdt_ping();
 738                 return 0;
 739         case WDIOC_SETTIMEOUT:
 740                 if (get_user(new_margin, (int __user *)arg))
 741                         return -EFAULT;
 742                 /* Arbitrary, can't find the card's limits */
 743                 if (new_margin < 1 || new_margin > 124)
 744                         return -EINVAL;
 745                 wdt_margin = new_margin;
 746                 wdt_ping();
 747                 /* Fall through */
 748         case WDIOC_GETTIMEOUT:
 749                 return put_user(wdt_margin, (int __user *)arg);
 750
 751         case WDIOC_SETOPTIONS:
 752                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 753                         return -EFAULT;
 754
 755                 if (rv & WDIOS_DISABLECARD) {
 756                         pr_info("disable watchdog\n");
 757                         wdt_disable();
 758                 }
 759
 760                 if (rv & WDIOS_ENABLECARD) {
 761                         pr_info("enable watchdog\n");
 762                         wdt_ping();
 763                 }
 764
 765                 return -EINVAL;
 766         }
 767         return -ENOTTY;
 768 }
 769
 770 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 771                                unsigned long arg)
 772 {
 773         int ret;
 774
 775         mutex_lock(&m41t80_rtc_mutex);
 776         ret = wdt_ioctl(file, cmd, arg);
 777         mutex_unlock(&m41t80_rtc_mutex);
 778
 779         return ret;
 780 }
 781
 782 /**
 783  *      wdt_open:
 784  *      @inode: inode of device
 785  *      @file: file handle to device
 786  *
 787  */
 788 static int wdt_open(struct inode *inode, struct file *file)
 789 {
 790         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 791                 mutex_lock(&m41t80_rtc_mutex);
 792                 if (test_and_set_bit(0, &wdt_is_open)) {
 793                         mutex_unlock(&m41t80_rtc_mutex);
 794                         return -EBUSY;
 795                 }
 796                 /*
 797                  *      Activate
 798                  */
 799                 wdt_is_open = 1;
 800                 mutex_unlock(&m41t80_rtc_mutex);
 801                 return stream_open(inode, file);
 802         }
 803         return -ENODEV;
 804 }
 805
 806 /**
 807  *      wdt_close:
 808  *      @inode: inode to board
 809  *      @file: file handle to board
 810  *
 811  */
 812 static int wdt_release(struct inode *inode, struct file *file)
 813 {
 814         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 815                 clear_bit(0, &wdt_is_open);
 816         return 0;
 817 }
 818
 819 /**
 820  *      notify_sys:
 821  *      @this: our notifier block
 822  *      @code: the event being reported
 823  *      @unused: unused
 824  *
 825  *      Our notifier is called on system shutdowns. We want to turn the card
 826  *      off at reboot otherwise the machine will reboot again during memory
 827  *      test or worse yet during the following fsck. This would suck, in fact
 828  *      trust me - if it happens it does suck.
 829  */
 830 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 831                           void *unused)
 832 {
 833         if (code == SYS_DOWN || code == SYS_HALT)
 834                 /* Disable Watchdog */
 835                 wdt_disable();
 836         return NOTIFY_DONE;
 837 }
 838
 839 static const struct file_operations wdt_fops = {
 840         .owner  = THIS_MODULE,
 841         .read   = wdt_read,
 842         .unlocked_ioctl = wdt_unlocked_ioctl,
 843         .write  = wdt_write,
 844         .open   = wdt_open,
 845         .release = wdt_release,
 846         .llseek = no_llseek,
 847 };
 848
 849 static struct miscdevice wdt_dev = {
 850         .minor = WATCHDOG_MINOR,
 851         .name = "watchdog",
 852         .fops = &wdt_fops,
 853 };
 854
 855 /*
 856  *      The WDT card needs to learn about soft shutdowns in order to
 857  *      turn the timebomb registers off.
 858  */
 859 static struct notifier_block wdt_notifier = {
 860         .notifier_call = wdt_notify_sys,
 861 };
 862 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 863
 864 /*
 865  *****************************************************************************
 866  *
 867  *      Driver Interface
 868  *
 869  *****************************************************************************
 870  */
 871
 872 static int m41t80_probe(struct i2c_client *client,
 873                         const struct i2c_device_id *id)
 874 {
 875         struct i2c_adapter *adapter = client->adapter;
 876         int rc = 0;
 877         struct rtc_time tm;
 878         struct m41t80_data *m41t80_data = NULL;
 879         bool wakeup_source = false;
 880
 881         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK |
 882                                      I2C_FUNC_SMBUS_BYTE_DATA)) {
 883                 dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
 884                 return -ENODEV;
 885         }
 886
 887         m41t80_data = devm_kzalloc(&client->dev, sizeof(*m41t80_data),
 888                                    GFP_KERNEL);
 889         if (!m41t80_data)
 890                 return -ENOMEM;
 891
 892         m41t80_data->client = client;
 893         if (client->dev.of_node)
 894                 m41t80_data->features = (unsigned long)
 895                         of_device_get_match_data(&client->dev);
 896         else
 897                 m41t80_data->features = id->driver_data;
 898         i2c_set_clientdata(client, m41t80_data);
 899
 900         m41t80_data->rtc =  devm_rtc_allocate_device(&client->dev);
 901         if (IS_ERR(m41t80_data->rtc))
 902                 return PTR_ERR(m41t80_data->rtc);
 903
 904 #ifdef CONFIG_OF
 905         wakeup_source = of_property_read_bool(client->dev.of_node,
 906                                               "wakeup-source");
 907 #endif
 908         if (client->irq > 0) {
 909                 rc = devm_request_threaded_irq(&client->dev, client->irq,
 910                                                NULL, m41t80_handle_irq,
 911                                                IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 912                                                "m41t80", client);
 913                 if (rc) {
 914                         dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
 915                         client->irq = 0;
 916                         wakeup_source = false;
 917                 }
 918         }
 919         if (client->irq > 0 || wakeup_source) {
 920                 m41t80_rtc_ops.read_alarm = m41t80_read_alarm;
 921                 m41t80_rtc_ops.set_alarm = m41t80_set_alarm;
 922                 m41t80_rtc_ops.alarm_irq_enable = m41t80_alarm_irq_enable;
 923                 /* Enable the wakealarm */
 924                 device_init_wakeup(&client->dev, true);
 925         }
 926
 927         m41t80_data->rtc->ops = &m41t80_rtc_ops;
 928
 929         if (client->irq <= 0) {
 930                 /* We cannot support UIE mode if we do not have an IRQ line */
 931                 m41t80_data->rtc->uie_unsupported = 1;
 932         }
 933
 934         /* Make sure HT (Halt Update) bit is cleared */
 935         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 936
 937         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 938                 if (m41t80_data->features & M41T80_FEATURE_HT) {
 939                         m41t80_rtc_read_time(&client->dev, &tm);
 940                         dev_info(&client->dev, "HT bit was set!\n");
 941                         dev_info(&client->dev, "Power Down at %ptR\n", &tm);
 942                 }
 943                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 944                                                rc & ~M41T80_ALHOUR_HT);
 945         }
 946
 947         if (rc < 0) {
 948                 dev_err(&client->dev, "Can't clear HT bit\n");
 949                 return rc;
 950         }
 951
 952         /* Make sure ST (stop) bit is cleared */
 953         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 954
 955         if (rc >= 0 && rc & M41T80_SEC_ST)
 956                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 957                                                rc & ~M41T80_SEC_ST);
 958         if (rc < 0) {
 959                 dev_err(&client->dev, "Can't clear ST bit\n");
 960                 return rc;
 961         }
 962
 963 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 964         if (m41t80_data->features & M41T80_FEATURE_HT) {
 965                 save_client = client;
 966                 rc = misc_register(&wdt_dev);
 967                 if (rc)
 968                         return rc;
 969                 rc = register_reboot_notifier(&wdt_notifier);
 970                 if (rc) {
 971                         misc_deregister(&wdt_dev);
 972                         return rc;
 973                 }
 974         }
 975 #endif
 976 #ifdef CONFIG_COMMON_CLK
 977         if (m41t80_data->features & M41T80_FEATURE_SQ)
 978                 m41t80_sqw_register_clk(m41t80_data);
 979 #endif
 980
 981         rc = rtc_register_device(m41t80_data->rtc);
 982         if (rc)
 983                 return rc;
 984
 985         return 0;
 986 }
 987
 988 static int m41t80_remove(struct i2c_client *client)
 989 {
 990 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 991         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 992
 993         if (clientdata->features & M41T80_FEATURE_HT) {
 994                 misc_deregister(&wdt_dev);
 995                 unregister_reboot_notifier(&wdt_notifier);
 996         }
 997 #endif
 998
 999         return 0;
1000 }
1001
1002 static struct i2c_driver m41t80_driver = {
1003         .driver = {
1004                 .name = "rtc-m41t80",
1005                 .of_match_table = of_match_ptr(m41t80_of_match),
1006                 .pm = &m41t80_pm,
1007         },
1008         .probe = m41t80_probe,
1009         .remove = m41t80_remove,
1010         .id_table = m41t80_id,
1011 };
1012
1013 module_i2c_driver(m41t80_driver);
1014
1015 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
1016 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
1017 MODULE_LICENSE("GPL");