drivers/rtc/rtc-m41t80.c

   1 /*
   2  * I2C client/driver for the ST M41T80 family of i2c rtc chips.
   3  *
   4  * Author: Alexander Bigga <ab@mycable.de>
   5  *
   6  * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
   7  *
   8  * 2006 (c) mycable GmbH
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/bcd.h>
  19 #include <linux/clk-provider.h>
  20 #include <linux/i2c.h>
  21 #include <linux/init.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/of_device.h>
  25 #include <linux/rtc.h>
  26 #include <linux/slab.h>
  27 #include <linux/mutex.h>
  28 #include <linux/string.h>
  29 #ifdef CONFIG_RTC_DRV_M41T80_WDT
  30 #include <linux/fs.h>
  31 #include <linux/ioctl.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/reboot.h>
  34 #include <linux/watchdog.h>
  35 #endif
  36
  37 #define M41T80_REG_SSEC         0x00
  38 #define M41T80_REG_SEC          0x01
  39 #define M41T80_REG_MIN          0x02
  40 #define M41T80_REG_HOUR         0x03
  41 #define M41T80_REG_WDAY         0x04
  42 #define M41T80_REG_DAY          0x05
  43 #define M41T80_REG_MON          0x06
  44 #define M41T80_REG_YEAR         0x07
  45 #define M41T80_REG_ALARM_MON    0x0a
  46 #define M41T80_REG_ALARM_DAY    0x0b
  47 #define M41T80_REG_ALARM_HOUR   0x0c
  48 #define M41T80_REG_ALARM_MIN    0x0d
  49 #define M41T80_REG_ALARM_SEC    0x0e
  50 #define M41T80_REG_FLAGS        0x0f
  51 #define M41T80_REG_SQW          0x13
  52
  53 #define M41T80_DATETIME_REG_SIZE        (M41T80_REG_YEAR + 1)
  54 #define M41T80_ALARM_REG_SIZE   \
  55         (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
  56
  57 #define M41T80_SQW_MAX_FREQ     32768
  58
  59 #define M41T80_SEC_ST           BIT(7)  /* ST: Stop Bit */
  60 #define M41T80_ALMON_AFE        BIT(7)  /* AFE: AF Enable Bit */
  61 #define M41T80_ALMON_SQWE       BIT(6)  /* SQWE: SQW Enable Bit */
  62 #define M41T80_ALHOUR_HT        BIT(6)  /* HT: Halt Update Bit */
  63 #define M41T80_FLAGS_OF         BIT(2)  /* OF: Oscillator Failure Bit */
  64 #define M41T80_FLAGS_AF         BIT(6)  /* AF: Alarm Flag Bit */
  65 #define M41T80_FLAGS_BATT_LOW   BIT(4)  /* BL: Battery Low Bit */
  66 #define M41T80_WATCHDOG_RB2     BIT(7)  /* RB: Watchdog resolution */
  67 #define M41T80_WATCHDOG_RB1     BIT(1)  /* RB: Watchdog resolution */
  68 #define M41T80_WATCHDOG_RB0     BIT(0)  /* RB: Watchdog resolution */
  69
  70 #define M41T80_FEATURE_HT       BIT(0)  /* Halt feature */
  71 #define M41T80_FEATURE_BL       BIT(1)  /* Battery low indicator */
  72 #define M41T80_FEATURE_SQ       BIT(2)  /* Squarewave feature */
  73 #define M41T80_FEATURE_WD       BIT(3)  /* Extra watchdog resolution */
  74 #define M41T80_FEATURE_SQ_ALT   BIT(4)  /* RSx bits are in reg 4 */
  75
  76 static const struct i2c_device_id m41t80_id[] = {
  77         { "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
  78         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  79         { "m41t80", M41T80_FEATURE_SQ },
  80         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  81         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  82         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  83         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  84         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  85         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  86         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  87         { "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
  88         { }
  89 };
  90 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  91
  92 static const struct of_device_id m41t80_of_match[] = {
  93         {
  94                 .compatible = "st,m41t62",
  95                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT)
  96         },
  97         {
  98                 .compatible = "st,m41t65",
  99                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_WD)
 100         },
 101         {
 102                 .compatible = "st,m41t80",
 103                 .data = (void *)(M41T80_FEATURE_SQ)
 104         },
 105         {
 106                 .compatible = "st,m41t81",
 107                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_SQ)
 108         },
 109         {
 110                 .compatible = "st,m41t81s",
 111                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 112         },
 113         {
 114                 .compatible = "st,m41t82",
 115                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 116         },
 117         {
 118                 .compatible = "st,m41t83",
 119                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 120         },
 121         {
 122                 .compatible = "st,m41t84",
 123                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 124         },
 125         {
 126                 .compatible = "st,m41t85",
 127                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 128         },
 129         {
 130                 .compatible = "st,m41t87",
 131                 .data = (void *)(M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ)
 132         },
 133         {
 134                 .compatible = "microcrystal,rv4162",
 135                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT)
 136         },
 137         /* DT compatibility only, do not use compatibles below: */
 138         {
 139                 .compatible = "st,rv4162",
 140                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT)
 141         },
 142         {
 143                 .compatible = "rv4162",
 144                 .data = (void *)(M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT)
 145         },
 146         { }
 147 };
 148 MODULE_DEVICE_TABLE(of, m41t80_of_match);
 149
 150 struct m41t80_data {
 151         unsigned long features;
 152         struct i2c_client *client;
 153         struct rtc_device *rtc;
 154 #ifdef CONFIG_COMMON_CLK
 155         struct clk_hw sqw;
 156         unsigned long freq;
 157         unsigned int sqwe;
 158 #endif
 159 };
 160
 161 static irqreturn_t m41t80_handle_irq(int irq, void *dev_id)
 162 {
 163         struct i2c_client *client = dev_id;
 164         struct m41t80_data *m41t80 = i2c_get_clientdata(client);
 165         struct mutex *lock = &m41t80->rtc->ops_lock;
 166         unsigned long events = 0;
 167         int flags, flags_afe;
 168
 169         mutex_lock(lock);
 170
 171         flags_afe = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 172         if (flags_afe < 0) {
 173                 mutex_unlock(lock);
 174                 return IRQ_NONE;
 175         }
 176
 177         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 178         if (flags <= 0) {
 179                 mutex_unlock(lock);
 180                 return IRQ_NONE;
 181         }
 182
 183         if (flags & M41T80_FLAGS_AF) {
 184                 flags &= ~M41T80_FLAGS_AF;
 185                 flags_afe &= ~M41T80_ALMON_AFE;
 186                 events |= RTC_AF;
 187         }
 188
 189         if (events) {
 190                 rtc_update_irq(m41t80->rtc, 1, events);
 191                 i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS, flags);
 192                 i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 193                                           flags_afe);
 194         }
 195
 196         mutex_unlock(lock);
 197
 198         return IRQ_HANDLED;
 199 }
 200
 201 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 202 {
 203         struct i2c_client *client = to_i2c_client(dev);
 204         unsigned char buf[8];
 205         int err, flags;
 206
 207         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 208         if (flags < 0)
 209                 return flags;
 210
 211         if (flags & M41T80_FLAGS_OF) {
 212                 dev_err(&client->dev, "Oscillator failure, data is invalid.\n");
 213                 return -EINVAL;
 214         }
 215
 216         err = i2c_smbus_read_i2c_block_data(client, M41T80_REG_SSEC,
 217                                             sizeof(buf), buf);
 218         if (err < 0) {
 219                 dev_err(&client->dev, "Unable to read date\n");
 220                 return err;
 221         }
 222
 223         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 224         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 225         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 226         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 227         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 228         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 229
 230         /* assume 20YY not 19YY, and ignore the Century Bit */
 231         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 232         return 0;
 233 }
 234
 235 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 236 {
 237         struct i2c_client *client = to_i2c_client(dev);
 238         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 239         unsigned char buf[8];
 240         int err, flags;
 241
 242         if (tm->tm_year < 100 || tm->tm_year > 199)
 243                 return -EINVAL;
 244
 245         buf[M41T80_REG_SSEC] = 0;
 246         buf[M41T80_REG_SEC] = bin2bcd(tm->tm_sec);
 247         buf[M41T80_REG_MIN] = bin2bcd(tm->tm_min);
 248         buf[M41T80_REG_HOUR] = bin2bcd(tm->tm_hour);
 249         buf[M41T80_REG_DAY] = bin2bcd(tm->tm_mday);
 250         buf[M41T80_REG_MON] = bin2bcd(tm->tm_mon + 1);
 251         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100);
 252         buf[M41T80_REG_WDAY] = tm->tm_wday;
 253
 254         /* If the square wave output is controlled in the weekday register */
 255         if (clientdata->features & M41T80_FEATURE_SQ_ALT) {
 256                 int val;
 257
 258                 val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY);
 259                 if (val < 0)
 260                         return val;
 261
 262                 buf[M41T80_REG_WDAY] |= (val & 0xf0);
 263         }
 264
 265         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC,
 266                                              sizeof(buf), buf);
 267         if (err < 0) {
 268                 dev_err(&client->dev, "Unable to write to date registers\n");
 269                 return err;
 270         }
 271
 272         /* Clear the OF bit of Flags Register */
 273         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 274         if (flags < 0)
 275                 return flags;
 276
 277         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 278                                         flags & ~M41T80_FLAGS_OF);
 279         if (err < 0) {
 280                 dev_err(&client->dev, "Unable to write flags register\n");
 281                 return err;
 282         }
 283
 284         return err;
 285 }
 286
 287 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 288 {
 289         struct i2c_client *client = to_i2c_client(dev);
 290         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 291         int reg;
 292
 293         if (clientdata->features & M41T80_FEATURE_BL) {
 294                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 295                 if (reg < 0)
 296                         return reg;
 297                 seq_printf(seq, "battery\t\t: %s\n",
 298                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 299         }
 300         return 0;
 301 }
 302
 303 static int m41t80_alarm_irq_enable(struct device *dev, unsigned int enabled)
 304 {
 305         struct i2c_client *client = to_i2c_client(dev);
 306         int flags, retval;
 307
 308         flags = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 309         if (flags < 0)
 310                 return flags;
 311
 312         if (enabled)
 313                 flags |= M41T80_ALMON_AFE;
 314         else
 315                 flags &= ~M41T80_ALMON_AFE;
 316
 317         retval = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, flags);
 318         if (retval < 0) {
 319                 dev_err(dev, "Unable to enable alarm IRQ %d\n", retval);
 320                 return retval;
 321         }
 322         return 0;
 323 }
 324
 325 static int m41t80_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 326 {
 327         struct i2c_client *client = to_i2c_client(dev);
 328         u8 alarmvals[5];
 329         int ret, err;
 330
 331         alarmvals[0] = bin2bcd(alrm->time.tm_mon + 1);
 332         alarmvals[1] = bin2bcd(alrm->time.tm_mday);
 333         alarmvals[2] = bin2bcd(alrm->time.tm_hour);
 334         alarmvals[3] = bin2bcd(alrm->time.tm_min);
 335         alarmvals[4] = bin2bcd(alrm->time.tm_sec);
 336
 337         /* Clear AF and AFE flags */
 338         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 339         if (ret < 0)
 340                 return ret;
 341         err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 342                                         ret & ~(M41T80_ALMON_AFE));
 343         if (err < 0) {
 344                 dev_err(dev, "Unable to clear AFE bit\n");
 345                 return err;
 346         }
 347
 348         /* Keep SQWE bit value */
 349         alarmvals[0] |= (ret & M41T80_ALMON_SQWE);
 350
 351         ret = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 352         if (ret < 0)
 353                 return ret;
 354
 355         err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 356                                         ret & ~(M41T80_FLAGS_AF));
 357         if (err < 0) {
 358                 dev_err(dev, "Unable to clear AF bit\n");
 359                 return err;
 360         }
 361
 362         /* Write the alarm */
 363         err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_ALARM_MON,
 364                                              5, alarmvals);
 365         if (err)
 366                 return err;
 367
 368         /* Enable the alarm interrupt */
 369         if (alrm->enabled) {
 370                 alarmvals[0] |= M41T80_ALMON_AFE;
 371                 err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 372                                                 alarmvals[0]);
 373                 if (err)
 374                         return err;
 375         }
 376
 377         return 0;
 378 }
 379
 380 static int m41t80_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 381 {
 382         struct i2c_client *client = to_i2c_client(dev);
 383         u8 alarmvals[5];
 384         int flags, ret;
 385
 386         ret = i2c_smbus_read_i2c_block_data(client, M41T80_REG_ALARM_MON,
 387                                             5, alarmvals);
 388         if (ret != 5)
 389                 return ret < 0 ? ret : -EIO;
 390
 391         flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 392         if (flags < 0)
 393                 return flags;
 394
 395         alrm->time.tm_sec  = bcd2bin(alarmvals[4] & 0x7f);
 396         alrm->time.tm_min  = bcd2bin(alarmvals[3] & 0x7f);
 397         alrm->time.tm_hour = bcd2bin(alarmvals[2] & 0x3f);
 398         alrm->time.tm_mday = bcd2bin(alarmvals[1] & 0x3f);
 399         alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f) - 1;
 400
 401         alrm->enabled = !!(alarmvals[0] & M41T80_ALMON_AFE);
 402         alrm->pending = (flags & M41T80_FLAGS_AF) && alrm->enabled;
 403
 404         return 0;
 405 }
 406
 407 static struct rtc_class_ops m41t80_rtc_ops = {
 408         .read_time = m41t80_rtc_read_time,
 409         .set_time = m41t80_rtc_set_time,
 410         .proc = m41t80_rtc_proc,
 411 };
 412
 413 #ifdef CONFIG_PM_SLEEP
 414 static int m41t80_suspend(struct device *dev)
 415 {
 416         struct i2c_client *client = to_i2c_client(dev);
 417
 418         if (client->irq >= 0 && device_may_wakeup(dev))
 419                 enable_irq_wake(client->irq);
 420
 421         return 0;
 422 }
 423
 424 static int m41t80_resume(struct device *dev)
 425 {
 426         struct i2c_client *client = to_i2c_client(dev);
 427
 428         if (client->irq >= 0 && device_may_wakeup(dev))
 429                 disable_irq_wake(client->irq);
 430
 431         return 0;
 432 }
 433 #endif
 434
 435 static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
 436
 437 #ifdef CONFIG_COMMON_CLK
 438 #define sqw_to_m41t80_data(_hw) container_of(_hw, struct m41t80_data, sqw)
 439
 440 static unsigned long m41t80_decode_freq(int setting)
 441 {
 442         return (setting == 0) ? 0 : (setting == 1) ? M41T80_SQW_MAX_FREQ :
 443                 M41T80_SQW_MAX_FREQ >> setting;
 444 }
 445
 446 static unsigned long m41t80_get_freq(struct m41t80_data *m41t80)
 447 {
 448         struct i2c_client *client = m41t80->client;
 449         int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 450                 M41T80_REG_WDAY : M41T80_REG_SQW;
 451         int ret = i2c_smbus_read_byte_data(client, reg_sqw);
 452
 453         if (ret < 0)
 454                 return 0;
 455         return m41t80_decode_freq(ret >> 4);
 456 }
 457
 458 static unsigned long m41t80_sqw_recalc_rate(struct clk_hw *hw,
 459                                             unsigned long parent_rate)
 460 {
 461         return sqw_to_m41t80_data(hw)->freq;
 462 }
 463
 464 static long m41t80_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
 465                                   unsigned long *prate)
 466 {
 467         if (rate >= M41T80_SQW_MAX_FREQ)
 468                 return M41T80_SQW_MAX_FREQ;
 469         if (rate >= M41T80_SQW_MAX_FREQ / 4)
 470                 return M41T80_SQW_MAX_FREQ / 4;
 471         if (!rate)
 472                 return 0;
 473         return 1 << ilog2(rate);
 474 }
 475
 476 static int m41t80_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
 477                                unsigned long parent_rate)
 478 {
 479         struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 480         struct i2c_client *client = m41t80->client;
 481         int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 482                 M41T80_REG_WDAY : M41T80_REG_SQW;
 483         int reg, ret, val = 0;
 484
 485         if (rate >= M41T80_SQW_MAX_FREQ)
 486                 val = 1;
 487         else if (rate >= M41T80_SQW_MAX_FREQ / 4)
 488                 val = 2;
 489         else if (rate)
 490                 val = 15 - ilog2(rate);
 491
 492         reg = i2c_smbus_read_byte_data(client, reg_sqw);
 493         if (reg < 0)
 494                 return reg;
 495
 496         reg = (reg & 0x0f) | (val << 4);
 497
 498         ret = i2c_smbus_write_byte_data(client, reg_sqw, reg);
 499         if (!ret)
 500                 m41t80->freq = m41t80_decode_freq(val);
 501         return ret;
 502 }
 503
 504 static int m41t80_sqw_control(struct clk_hw *hw, bool enable)
 505 {
 506         struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 507         struct i2c_client *client = m41t80->client;
 508         int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 509
 510         if (ret < 0)
 511                 return ret;
 512
 513         if (enable)
 514                 ret |= M41T80_ALMON_SQWE;
 515         else
 516                 ret &= ~M41T80_ALMON_SQWE;
 517
 518         ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret);
 519         if (!ret)
 520                 m41t80->sqwe = enable;
 521         return ret;
 522 }
 523
 524 static int m41t80_sqw_prepare(struct clk_hw *hw)
 525 {
 526         return m41t80_sqw_control(hw, 1);
 527 }
 528
 529 static void m41t80_sqw_unprepare(struct clk_hw *hw)
 530 {
 531         m41t80_sqw_control(hw, 0);
 532 }
 533
 534 static int m41t80_sqw_is_prepared(struct clk_hw *hw)
 535 {
 536         return sqw_to_m41t80_data(hw)->sqwe;
 537 }
 538
 539 static const struct clk_ops m41t80_sqw_ops = {
 540         .prepare = m41t80_sqw_prepare,
 541         .unprepare = m41t80_sqw_unprepare,
 542         .is_prepared = m41t80_sqw_is_prepared,
 543         .recalc_rate = m41t80_sqw_recalc_rate,
 544         .round_rate = m41t80_sqw_round_rate,
 545         .set_rate = m41t80_sqw_set_rate,
 546 };
 547
 548 static struct clk *m41t80_sqw_register_clk(struct m41t80_data *m41t80)
 549 {
 550         struct i2c_client *client = m41t80->client;
 551         struct device_node *node = client->dev.of_node;
 552         struct clk *clk;
 553         struct clk_init_data init;
 554         int ret;
 555
 556         /* First disable the clock */
 557         ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 558         if (ret < 0)
 559                 return ERR_PTR(ret);
 560         ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 561                                         ret & ~(M41T80_ALMON_SQWE));
 562         if (ret < 0)
 563                 return ERR_PTR(ret);
 564
 565         init.name = "m41t80-sqw";
 566         init.ops = &m41t80_sqw_ops;
 567         init.flags = 0;
 568         init.parent_names = NULL;
 569         init.num_parents = 0;
 570         m41t80->sqw.init = &init;
 571         m41t80->freq = m41t80_get_freq(m41t80);
 572
 573         /* optional override of the clockname */
 574         of_property_read_string(node, "clock-output-names", &init.name);
 575
 576         /* register the clock */
 577         clk = clk_register(&client->dev, &m41t80->sqw);
 578         if (!IS_ERR(clk))
 579                 of_clk_add_provider(node, of_clk_src_simple_get, clk);
 580
 581         return clk;
 582 }
 583 #endif
 584
 585 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 586 /*
 587  *****************************************************************************
 588  *
 589  * Watchdog Driver
 590  *
 591  *****************************************************************************
 592  */
 593 static DEFINE_MUTEX(m41t80_rtc_mutex);
 594 static struct i2c_client *save_client;
 595
 596 /* Default margin */
 597 #define WD_TIMO 60              /* 1..31 seconds */
 598
 599 static int wdt_margin = WD_TIMO;
 600 module_param(wdt_margin, int, 0);
 601 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 602
 603 static unsigned long wdt_is_open;
 604 static int boot_flag;
 605
 606 /**
 607  *      wdt_ping:
 608  *
 609  *      Reload counter one with the watchdog timeout. We don't bother reloading
 610  *      the cascade counter.
 611  */
 612 static void wdt_ping(void)
 613 {
 614         unsigned char i2c_data[2];
 615         struct i2c_msg msgs1[1] = {
 616                 {
 617                         .addr   = save_client->addr,
 618                         .flags  = 0,
 619                         .len    = 2,
 620                         .buf    = i2c_data,
 621                 },
 622         };
 623         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 624
 625         i2c_data[0] = 0x09;             /* watchdog register */
 626
 627         if (wdt_margin > 31)
 628                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 629         else
 630                 /*
 631                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 632                  */
 633                 i2c_data[1] = wdt_margin << 2 | 0x82;
 634
 635         /*
 636          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 637          * that would be an invalid resolution.
 638          */
 639         if (clientdata->features & M41T80_FEATURE_WD)
 640                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 641
 642         i2c_transfer(save_client->adapter, msgs1, 1);
 643 }
 644
 645 /**
 646  *      wdt_disable:
 647  *
 648  *      disables watchdog.
 649  */
 650 static void wdt_disable(void)
 651 {
 652         unsigned char i2c_data[2], i2c_buf[0x10];
 653         struct i2c_msg msgs0[2] = {
 654                 {
 655                         .addr   = save_client->addr,
 656                         .flags  = 0,
 657                         .len    = 1,
 658                         .buf    = i2c_data,
 659                 },
 660                 {
 661                         .addr   = save_client->addr,
 662                         .flags  = I2C_M_RD,
 663                         .len    = 1,
 664                         .buf    = i2c_buf,
 665                 },
 666         };
 667         struct i2c_msg msgs1[1] = {
 668                 {
 669                         .addr   = save_client->addr,
 670                         .flags  = 0,
 671                         .len    = 2,
 672                         .buf    = i2c_data,
 673                 },
 674         };
 675
 676         i2c_data[0] = 0x09;
 677         i2c_transfer(save_client->adapter, msgs0, 2);
 678
 679         i2c_data[0] = 0x09;
 680         i2c_data[1] = 0x00;
 681         i2c_transfer(save_client->adapter, msgs1, 1);
 682 }
 683
 684 /**
 685  *      wdt_write:
 686  *      @file: file handle to the watchdog
 687  *      @buf: buffer to write (unused as data does not matter here
 688  *      @count: count of bytes
 689  *      @ppos: pointer to the position to write. No seeks allowed
 690  *
 691  *      A write to a watchdog device is defined as a keepalive signal. Any
 692  *      write of data will do, as we we don't define content meaning.
 693  */
 694 static ssize_t wdt_write(struct file *file, const char __user *buf,
 695                          size_t count, loff_t *ppos)
 696 {
 697         if (count) {
 698                 wdt_ping();
 699                 return 1;
 700         }
 701         return 0;
 702 }
 703
 704 static ssize_t wdt_read(struct file *file, char __user *buf,
 705                         size_t count, loff_t *ppos)
 706 {
 707         return 0;
 708 }
 709
 710 /**
 711  *      wdt_ioctl:
 712  *      @inode: inode of the device
 713  *      @file: file handle to the device
 714  *      @cmd: watchdog command
 715  *      @arg: argument pointer
 716  *
 717  *      The watchdog API defines a common set of functions for all watchdogs
 718  *      according to their available features. We only actually usefully support
 719  *      querying capabilities and current status.
 720  */
 721 static int wdt_ioctl(struct file *file, unsigned int cmd,
 722                      unsigned long arg)
 723 {
 724         int new_margin, rv;
 725         static struct watchdog_info ident = {
 726                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 727                         WDIOF_SETTIMEOUT,
 728                 .firmware_version = 1,
 729                 .identity = "M41T80 WTD"
 730         };
 731
 732         switch (cmd) {
 733         case WDIOC_GETSUPPORT:
 734                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 735                                     sizeof(ident)) ? -EFAULT : 0;
 736
 737         case WDIOC_GETSTATUS:
 738         case WDIOC_GETBOOTSTATUS:
 739                 return put_user(boot_flag, (int __user *)arg);
 740         case WDIOC_KEEPALIVE:
 741                 wdt_ping();
 742                 return 0;
 743         case WDIOC_SETTIMEOUT:
 744                 if (get_user(new_margin, (int __user *)arg))
 745                         return -EFAULT;
 746                 /* Arbitrary, can't find the card's limits */
 747                 if (new_margin < 1 || new_margin > 124)
 748                         return -EINVAL;
 749                 wdt_margin = new_margin;
 750                 wdt_ping();
 751                 /* Fall through */
 752         case WDIOC_GETTIMEOUT:
 753                 return put_user(wdt_margin, (int __user *)arg);
 754
 755         case WDIOC_SETOPTIONS:
 756                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 757                         return -EFAULT;
 758
 759                 if (rv & WDIOS_DISABLECARD) {
 760                         pr_info("disable watchdog\n");
 761                         wdt_disable();
 762                 }
 763
 764                 if (rv & WDIOS_ENABLECARD) {
 765                         pr_info("enable watchdog\n");
 766                         wdt_ping();
 767                 }
 768
 769                 return -EINVAL;
 770         }
 771         return -ENOTTY;
 772 }
 773
 774 static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 775                                unsigned long arg)
 776 {
 777         int ret;
 778
 779         mutex_lock(&m41t80_rtc_mutex);
 780         ret = wdt_ioctl(file, cmd, arg);
 781         mutex_unlock(&m41t80_rtc_mutex);
 782
 783         return ret;
 784 }
 785
 786 /**
 787  *      wdt_open:
 788  *      @inode: inode of device
 789  *      @file: file handle to device
 790  *
 791  */
 792 static int wdt_open(struct inode *inode, struct file *file)
 793 {
 794         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 795                 mutex_lock(&m41t80_rtc_mutex);
 796                 if (test_and_set_bit(0, &wdt_is_open)) {
 797                         mutex_unlock(&m41t80_rtc_mutex);
 798                         return -EBUSY;
 799                 }
 800                 /*
 801                  *      Activate
 802                  */
 803                 wdt_is_open = 1;
 804                 mutex_unlock(&m41t80_rtc_mutex);
 805                 return stream_open(inode, file);
 806         }
 807         return -ENODEV;
 808 }
 809
 810 /**
 811  *      wdt_close:
 812  *      @inode: inode to board
 813  *      @file: file handle to board
 814  *
 815  */
 816 static int wdt_release(struct inode *inode, struct file *file)
 817 {
 818         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 819                 clear_bit(0, &wdt_is_open);
 820         return 0;
 821 }
 822
 823 /**
 824  *      notify_sys:
 825  *      @this: our notifier block
 826  *      @code: the event being reported
 827  *      @unused: unused
 828  *
 829  *      Our notifier is called on system shutdowns. We want to turn the card
 830  *      off at reboot otherwise the machine will reboot again during memory
 831  *      test or worse yet during the following fsck. This would suck, in fact
 832  *      trust me - if it happens it does suck.
 833  */
 834 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 835                           void *unused)
 836 {
 837         if (code == SYS_DOWN || code == SYS_HALT)
 838                 /* Disable Watchdog */
 839                 wdt_disable();
 840         return NOTIFY_DONE;
 841 }
 842
 843 static const struct file_operations wdt_fops = {
 844         .owner  = THIS_MODULE,
 845         .read   = wdt_read,
 846         .unlocked_ioctl = wdt_unlocked_ioctl,
 847         .write  = wdt_write,
 848         .open   = wdt_open,
 849         .release = wdt_release,
 850         .llseek = no_llseek,
 851 };
 852
 853 static struct miscdevice wdt_dev = {
 854         .minor = WATCHDOG_MINOR,
 855         .name = "watchdog",
 856         .fops = &wdt_fops,
 857 };
 858
 859 /*
 860  *      The WDT card needs to learn about soft shutdowns in order to
 861  *      turn the timebomb registers off.
 862  */
 863 static struct notifier_block wdt_notifier = {
 864         .notifier_call = wdt_notify_sys,
 865 };
 866 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 867
 868 /*
 869  *****************************************************************************
 870  *
 871  *      Driver Interface
 872  *
 873  *****************************************************************************
 874  */
 875
 876 static int m41t80_probe(struct i2c_client *client,
 877                         const struct i2c_device_id *id)
 878 {
 879         struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
 880         int rc = 0;
 881         struct rtc_time tm;
 882         struct m41t80_data *m41t80_data = NULL;
 883         bool wakeup_source = false;
 884
 885         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK |
 886                                      I2C_FUNC_SMBUS_BYTE_DATA)) {
 887                 dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
 888                 return -ENODEV;
 889         }
 890
 891         m41t80_data = devm_kzalloc(&client->dev, sizeof(*m41t80_data),
 892                                    GFP_KERNEL);
 893         if (!m41t80_data)
 894                 return -ENOMEM;
 895
 896         m41t80_data->client = client;
 897         if (client->dev.of_node)
 898                 m41t80_data->features = (unsigned long)
 899                         of_device_get_match_data(&client->dev);
 900         else
 901                 m41t80_data->features = id->driver_data;
 902         i2c_set_clientdata(client, m41t80_data);
 903
 904         m41t80_data->rtc =  devm_rtc_allocate_device(&client->dev);
 905         if (IS_ERR(m41t80_data->rtc))
 906                 return PTR_ERR(m41t80_data->rtc);
 907
 908 #ifdef CONFIG_OF
 909         wakeup_source = of_property_read_bool(client->dev.of_node,
 910                                               "wakeup-source");
 911 #endif
 912         if (client->irq > 0) {
 913                 rc = devm_request_threaded_irq(&client->dev, client->irq,
 914                                                NULL, m41t80_handle_irq,
 915                                                IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 916                                                "m41t80", client);
 917                 if (rc) {
 918                         dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
 919                         client->irq = 0;
 920                         wakeup_source = false;
 921                 }
 922         }
 923         if (client->irq > 0 || wakeup_source) {
 924                 m41t80_rtc_ops.read_alarm = m41t80_read_alarm;
 925                 m41t80_rtc_ops.set_alarm = m41t80_set_alarm;
 926                 m41t80_rtc_ops.alarm_irq_enable = m41t80_alarm_irq_enable;
 927                 /* Enable the wakealarm */
 928                 device_init_wakeup(&client->dev, true);
 929         }
 930
 931         m41t80_data->rtc->ops = &m41t80_rtc_ops;
 932
 933         if (client->irq <= 0) {
 934                 /* We cannot support UIE mode if we do not have an IRQ line */
 935                 m41t80_data->rtc->uie_unsupported = 1;
 936         }
 937
 938         /* Make sure HT (Halt Update) bit is cleared */
 939         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 940
 941         if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 942                 if (m41t80_data->features & M41T80_FEATURE_HT) {
 943                         m41t80_rtc_read_time(&client->dev, &tm);
 944                         dev_info(&client->dev, "HT bit was set!\n");
 945                         dev_info(&client->dev, "Power Down at %ptR\n", &tm);
 946                 }
 947                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 948                                                rc & ~M41T80_ALHOUR_HT);
 949         }
 950
 951         if (rc < 0) {
 952                 dev_err(&client->dev, "Can't clear HT bit\n");
 953                 return rc;
 954         }
 955
 956         /* Make sure ST (stop) bit is cleared */
 957         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 958
 959         if (rc >= 0 && rc & M41T80_SEC_ST)
 960                 rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 961                                                rc & ~M41T80_SEC_ST);
 962         if (rc < 0) {
 963                 dev_err(&client->dev, "Can't clear ST bit\n");
 964                 return rc;
 965         }
 966
 967 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 968         if (m41t80_data->features & M41T80_FEATURE_HT) {
 969                 save_client = client;
 970                 rc = misc_register(&wdt_dev);
 971                 if (rc)
 972                         return rc;
 973                 rc = register_reboot_notifier(&wdt_notifier);
 974                 if (rc) {
 975                         misc_deregister(&wdt_dev);
 976                         return rc;
 977                 }
 978         }
 979 #endif
 980 #ifdef CONFIG_COMMON_CLK
 981         if (m41t80_data->features & M41T80_FEATURE_SQ)
 982                 m41t80_sqw_register_clk(m41t80_data);
 983 #endif
 984
 985         rc = rtc_register_device(m41t80_data->rtc);
 986         if (rc)
 987                 return rc;
 988
 989         return 0;
 990 }
 991
 992 static int m41t80_remove(struct i2c_client *client)
 993 {
 994 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 995         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 996
 997         if (clientdata->features & M41T80_FEATURE_HT) {
 998                 misc_deregister(&wdt_dev);
 999                 unregister_reboot_notifier(&wdt_notifier);
1000         }
1001 #endif
1002
1003         return 0;
1004 }
1005
1006 static struct i2c_driver m41t80_driver = {
1007         .driver = {
1008                 .name = "rtc-m41t80",
1009                 .of_match_table = of_match_ptr(m41t80_of_match),
1010                 .pm = &m41t80_pm,
1011         },
1012         .probe = m41t80_probe,
1013         .remove = m41t80_remove,
1014         .id_table = m41t80_id,
1015 };
1016
1017 module_i2c_driver(m41t80_driver);
1018
1019 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
1020 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
1021 MODULE_LICENSE("GPL");