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 #include <linux/bcd.h>
  17 #include <linux/i2c.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/rtc.h>
  22 #include <linux/slab.h>
  23 #include <linux/smp_lock.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 0
  34 #define M41T80_REG_SEC  1
  35 #define M41T80_REG_MIN  2
  36 #define M41T80_REG_HOUR 3
  37 #define M41T80_REG_WDAY 4
  38 #define M41T80_REG_DAY  5
  39 #define M41T80_REG_MON  6
  40 #define M41T80_REG_YEAR 7
  41 #define M41T80_REG_ALARM_MON    0xa
  42 #define M41T80_REG_ALARM_DAY    0xb
  43 #define M41T80_REG_ALARM_HOUR   0xc
  44 #define M41T80_REG_ALARM_MIN    0xd
  45 #define M41T80_REG_ALARM_SEC    0xe
  46 #define M41T80_REG_FLAGS        0xf
  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_SEC_ST           (1 << 7)        /* ST: Stop Bit */
  54 #define M41T80_ALMON_AFE        (1 << 7)        /* AFE: AF Enable Bit */
  55 #define M41T80_ALMON_SQWE       (1 << 6)        /* SQWE: SQW Enable Bit */
  56 #define M41T80_ALHOUR_HT        (1 << 6)        /* HT: Halt Update Bit */
  57 #define M41T80_FLAGS_AF         (1 << 6)        /* AF: Alarm Flag Bit */
  58 #define M41T80_FLAGS_BATT_LOW   (1 << 4)        /* BL: Battery Low Bit */
  59 #define M41T80_WATCHDOG_RB2     (1 << 7)        /* RB: Watchdog resolution */
  60 #define M41T80_WATCHDOG_RB1     (1 << 1)        /* RB: Watchdog resolution */
  61 #define M41T80_WATCHDOG_RB0     (1 << 0)        /* RB: Watchdog resolution */
  62
  63 #define M41T80_FEATURE_HT       (1 << 0)        /* Halt feature */
  64 #define M41T80_FEATURE_BL       (1 << 1)        /* Battery low indicator */
  65 #define M41T80_FEATURE_SQ       (1 << 2)        /* Squarewave feature */
  66 #define M41T80_FEATURE_WD       (1 << 3)        /* Extra watchdog resolution */
  67
  68 #define DRV_VERSION "0.05"
  69
  70 static const struct i2c_device_id m41t80_id[] = {
  71         { "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
  72         { "m41t80", M41T80_FEATURE_SQ },
  73         { "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
  74         { "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  75         { "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  76         { "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  77         { "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  78         { "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  79         { "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
  80         { }
  81 };
  82 MODULE_DEVICE_TABLE(i2c, m41t80_id);
  83
  84 struct m41t80_data {
  85         u8 features;
  86         struct rtc_device *rtc;
  87 };
  88
  89 static int m41t80_get_datetime(struct i2c_client *client,
  90                                struct rtc_time *tm)
  91 {
  92         u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
  93         struct i2c_msg msgs[] = {
  94                 {
  95                         .addr   = client->addr,
  96                         .flags  = 0,
  97                         .len    = 1,
  98                         .buf    = dt_addr,
  99                 },
 100                 {
 101                         .addr   = client->addr,
 102                         .flags  = I2C_M_RD,
 103                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 104                         .buf    = buf + M41T80_REG_SEC,
 105                 },
 106         };
 107
 108         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 109                 dev_err(&client->dev, "read error\n");
 110                 return -EIO;
 111         }
 112
 113         tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 114         tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 115         tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 116         tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 117         tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 118         tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 119
 120         /* assume 20YY not 19YY, and ignore the Century Bit */
 121         tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 122         return 0;
 123 }
 124
 125 /* Sets the given date and time to the real time clock. */
 126 static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 127 {
 128         u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
 129         u8 *buf = &wbuf[1];
 130         u8 dt_addr[1] = { M41T80_REG_SEC };
 131         struct i2c_msg msgs_in[] = {
 132                 {
 133                         .addr   = client->addr,
 134                         .flags  = 0,
 135                         .len    = 1,
 136                         .buf    = dt_addr,
 137                 },
 138                 {
 139                         .addr   = client->addr,
 140                         .flags  = I2C_M_RD,
 141                         .len    = M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
 142                         .buf    = buf + M41T80_REG_SEC,
 143                 },
 144         };
 145         struct i2c_msg msgs[] = {
 146                 {
 147                         .addr   = client->addr,
 148                         .flags  = 0,
 149                         .len    = 1 + M41T80_DATETIME_REG_SIZE,
 150                         .buf    = wbuf,
 151                  },
 152         };
 153
 154         /* Read current reg values into buf[1..7] */
 155         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 156                 dev_err(&client->dev, "read error\n");
 157                 return -EIO;
 158         }
 159
 160         wbuf[0] = 0; /* offset into rtc's regs */
 161         /* Merge time-data and register flags into buf[0..7] */
 162         buf[M41T80_REG_SSEC] = 0;
 163         buf[M41T80_REG_SEC] =
 164                 bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
 165         buf[M41T80_REG_MIN] =
 166                 bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
 167         buf[M41T80_REG_HOUR] =
 168                 bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f) ;
 169         buf[M41T80_REG_WDAY] =
 170                 (tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
 171         buf[M41T80_REG_DAY] =
 172                 bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
 173         buf[M41T80_REG_MON] =
 174                 bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
 175         /* assume 20YY not 19YY */
 176         buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
 177
 178         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 179                 dev_err(&client->dev, "write error\n");
 180                 return -EIO;
 181         }
 182         return 0;
 183 }
 184
 185 #if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
 186 static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 187 {
 188         struct i2c_client *client = to_i2c_client(dev);
 189         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 190         u8 reg;
 191
 192         if (clientdata->features & M41T80_FEATURE_BL) {
 193                 reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 194                 seq_printf(seq, "battery\t\t: %s\n",
 195                            (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 196         }
 197         return 0;
 198 }
 199 #else
 200 #define m41t80_rtc_proc NULL
 201 #endif
 202
 203 static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 204 {
 205         return m41t80_get_datetime(to_i2c_client(dev), tm);
 206 }
 207
 208 static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 209 {
 210         return m41t80_set_datetime(to_i2c_client(dev), tm);
 211 }
 212
 213 #if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
 214 static int
 215 m41t80_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 216 {
 217         struct i2c_client *client = to_i2c_client(dev);
 218         int rc;
 219
 220         switch (cmd) {
 221         case RTC_AIE_OFF:
 222         case RTC_AIE_ON:
 223                 break;
 224         default:
 225                 return -ENOIOCTLCMD;
 226         }
 227
 228         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 229         if (rc < 0)
 230                 goto err;
 231         switch (cmd) {
 232         case RTC_AIE_OFF:
 233                 rc &= ~M41T80_ALMON_AFE;
 234                 break;
 235         case RTC_AIE_ON:
 236                 rc |= M41T80_ALMON_AFE;
 237                 break;
 238         }
 239         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
 240                 goto err;
 241         return 0;
 242 err:
 243         return -EIO;
 244 }
 245 #else
 246 #define m41t80_rtc_ioctl NULL
 247 #endif
 248
 249 static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 250 {
 251         struct i2c_client *client = to_i2c_client(dev);
 252         u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
 253         u8 *buf = &wbuf[1];
 254         u8 *reg = buf - M41T80_REG_ALARM_MON;
 255         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 256         struct i2c_msg msgs_in[] = {
 257                 {
 258                         .addr   = client->addr,
 259                         .flags  = 0,
 260                         .len    = 1,
 261                         .buf    = dt_addr,
 262                 },
 263                 {
 264                         .addr   = client->addr,
 265                         .flags  = I2C_M_RD,
 266                         .len    = M41T80_ALARM_REG_SIZE,
 267                         .buf    = buf,
 268                 },
 269         };
 270         struct i2c_msg msgs[] = {
 271                 {
 272                         .addr   = client->addr,
 273                         .flags  = 0,
 274                         .len    = 1 + M41T80_ALARM_REG_SIZE,
 275                         .buf    = wbuf,
 276                  },
 277         };
 278
 279         if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
 280                 dev_err(&client->dev, "read error\n");
 281                 return -EIO;
 282         }
 283         reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
 284         reg[M41T80_REG_ALARM_DAY] = 0;
 285         reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
 286         reg[M41T80_REG_ALARM_MIN] = 0;
 287         reg[M41T80_REG_ALARM_SEC] = 0;
 288
 289         wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
 290         reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
 291                 bin2bcd(t->time.tm_sec) : 0x80;
 292         reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
 293                 bin2bcd(t->time.tm_min) : 0x80;
 294         reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
 295                 bin2bcd(t->time.tm_hour) : 0x80;
 296         reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
 297                 bin2bcd(t->time.tm_mday) : 0x80;
 298         if (t->time.tm_mon >= 0)
 299                 reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
 300         else
 301                 reg[M41T80_REG_ALARM_DAY] |= 0x40;
 302
 303         if (i2c_transfer(client->adapter, msgs, 1) != 1) {
 304                 dev_err(&client->dev, "write error\n");
 305                 return -EIO;
 306         }
 307
 308         if (t->enabled) {
 309                 reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
 310                 if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 311                                               reg[M41T80_REG_ALARM_MON]) < 0) {
 312                         dev_err(&client->dev, "write error\n");
 313                         return -EIO;
 314                 }
 315         }
 316         return 0;
 317 }
 318
 319 static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 320 {
 321         struct i2c_client *client = to_i2c_client(dev);
 322         u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
 323         u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
 324         u8 *reg = buf - M41T80_REG_ALARM_MON;
 325         struct i2c_msg msgs[] = {
 326                 {
 327                         .addr   = client->addr,
 328                         .flags  = 0,
 329                         .len    = 1,
 330                         .buf    = dt_addr,
 331                 },
 332                 {
 333                         .addr   = client->addr,
 334                         .flags  = I2C_M_RD,
 335                         .len    = M41T80_ALARM_REG_SIZE + 1,
 336                         .buf    = buf,
 337                 },
 338         };
 339
 340         if (i2c_transfer(client->adapter, msgs, 2) < 0) {
 341                 dev_err(&client->dev, "read error\n");
 342                 return -EIO;
 343         }
 344         t->time.tm_sec = -1;
 345         t->time.tm_min = -1;
 346         t->time.tm_hour = -1;
 347         t->time.tm_mday = -1;
 348         t->time.tm_mon = -1;
 349         if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
 350                 t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
 351         if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
 352                 t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
 353         if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
 354                 t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
 355         if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
 356                 t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
 357         if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
 358                 t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
 359         t->time.tm_year = -1;
 360         t->time.tm_wday = -1;
 361         t->time.tm_yday = -1;
 362         t->time.tm_isdst = -1;
 363         t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
 364         t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
 365         return 0;
 366 }
 367
 368 static struct rtc_class_ops m41t80_rtc_ops = {
 369         .read_time = m41t80_rtc_read_time,
 370         .set_time = m41t80_rtc_set_time,
 371         .read_alarm = m41t80_rtc_read_alarm,
 372         .set_alarm = m41t80_rtc_set_alarm,
 373         .proc = m41t80_rtc_proc,
 374         .ioctl = m41t80_rtc_ioctl,
 375 };
 376
 377 #if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
 378 static ssize_t m41t80_sysfs_show_flags(struct device *dev,
 379                                 struct device_attribute *attr, char *buf)
 380 {
 381         struct i2c_client *client = to_i2c_client(dev);
 382         int val;
 383
 384         val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 385         if (val < 0)
 386                 return -EIO;
 387         return sprintf(buf, "%#x\n", val);
 388 }
 389 static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
 390
 391 static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
 392                                 struct device_attribute *attr, char *buf)
 393 {
 394         struct i2c_client *client = to_i2c_client(dev);
 395         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 396         int val;
 397
 398         if (!(clientdata->features & M41T80_FEATURE_SQ))
 399                 return -EINVAL;
 400
 401         val = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
 402         if (val < 0)
 403                 return -EIO;
 404         val = (val >> 4) & 0xf;
 405         switch (val) {
 406         case 0:
 407                 break;
 408         case 1:
 409                 val = 32768;
 410                 break;
 411         default:
 412                 val = 32768 >> val;
 413         }
 414         return sprintf(buf, "%d\n", val);
 415 }
 416 static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
 417                                 struct device_attribute *attr,
 418                                 const char *buf, size_t count)
 419 {
 420         struct i2c_client *client = to_i2c_client(dev);
 421         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 422         int almon, sqw;
 423         int val = simple_strtoul(buf, NULL, 0);
 424
 425         if (!(clientdata->features & M41T80_FEATURE_SQ))
 426                 return -EINVAL;
 427
 428         if (val) {
 429                 if (!is_power_of_2(val))
 430                         return -EINVAL;
 431                 val = ilog2(val);
 432                 if (val == 15)
 433                         val = 1;
 434                 else if (val < 14)
 435                         val = 15 - val;
 436                 else
 437                         return -EINVAL;
 438         }
 439         /* disable SQW, set SQW frequency & re-enable */
 440         almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 441         if (almon < 0)
 442                 return -EIO;
 443         sqw = i2c_smbus_read_byte_data(client, M41T80_REG_SQW);
 444         if (sqw < 0)
 445                 return -EIO;
 446         sqw = (sqw & 0x0f) | (val << 4);
 447         if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 448                                       almon & ~M41T80_ALMON_SQWE) < 0 ||
 449             i2c_smbus_write_byte_data(client, M41T80_REG_SQW, sqw) < 0)
 450                 return -EIO;
 451         if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 452                                              almon | M41T80_ALMON_SQWE) < 0)
 453                 return -EIO;
 454         return count;
 455 }
 456 static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
 457                    m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
 458
 459 static struct attribute *attrs[] = {
 460         &dev_attr_flags.attr,
 461         &dev_attr_sqwfreq.attr,
 462         NULL,
 463 };
 464 static struct attribute_group attr_group = {
 465         .attrs = attrs,
 466 };
 467
 468 static int m41t80_sysfs_register(struct device *dev)
 469 {
 470         return sysfs_create_group(&dev->kobj, &attr_group);
 471 }
 472 #else
 473 static int m41t80_sysfs_register(struct device *dev)
 474 {
 475         return 0;
 476 }
 477 #endif
 478
 479 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 480 /*
 481  *****************************************************************************
 482  *
 483  * Watchdog Driver
 484  *
 485  *****************************************************************************
 486  */
 487 static struct i2c_client *save_client;
 488
 489 /* Default margin */
 490 #define WD_TIMO 60              /* 1..31 seconds */
 491
 492 static int wdt_margin = WD_TIMO;
 493 module_param(wdt_margin, int, 0);
 494 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 495
 496 static unsigned long wdt_is_open;
 497 static int boot_flag;
 498
 499 /**
 500  *      wdt_ping:
 501  *
 502  *      Reload counter one with the watchdog timeout. We don't bother reloading
 503  *      the cascade counter.
 504  */
 505 static void wdt_ping(void)
 506 {
 507         unsigned char i2c_data[2];
 508         struct i2c_msg msgs1[1] = {
 509                 {
 510                         .addr   = save_client->addr,
 511                         .flags  = 0,
 512                         .len    = 2,
 513                         .buf    = i2c_data,
 514                 },
 515         };
 516         struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 517
 518         i2c_data[0] = 0x09;             /* watchdog register */
 519
 520         if (wdt_margin > 31)
 521                 i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 522         else
 523                 /*
 524                  * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 525                  */
 526                 i2c_data[1] = wdt_margin<<2 | 0x82;
 527
 528         /*
 529          * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 530          * that would be an invalid resolution.
 531          */
 532         if (clientdata->features & M41T80_FEATURE_WD)
 533                 i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 534
 535         i2c_transfer(save_client->adapter, msgs1, 1);
 536 }
 537
 538 /**
 539  *      wdt_disable:
 540  *
 541  *      disables watchdog.
 542  */
 543 static void wdt_disable(void)
 544 {
 545         unsigned char i2c_data[2], i2c_buf[0x10];
 546         struct i2c_msg msgs0[2] = {
 547                 {
 548                         .addr   = save_client->addr,
 549                         .flags  = 0,
 550                         .len    = 1,
 551                         .buf    = i2c_data,
 552                 },
 553                 {
 554                         .addr   = save_client->addr,
 555                         .flags  = I2C_M_RD,
 556                         .len    = 1,
 557                         .buf    = i2c_buf,
 558                 },
 559         };
 560         struct i2c_msg msgs1[1] = {
 561                 {
 562                         .addr   = save_client->addr,
 563                         .flags  = 0,
 564                         .len    = 2,
 565                         .buf    = i2c_data,
 566                 },
 567         };
 568
 569         i2c_data[0] = 0x09;
 570         i2c_transfer(save_client->adapter, msgs0, 2);
 571
 572         i2c_data[0] = 0x09;
 573         i2c_data[1] = 0x00;
 574         i2c_transfer(save_client->adapter, msgs1, 1);
 575 }
 576
 577 /**
 578  *      wdt_write:
 579  *      @file: file handle to the watchdog
 580  *      @buf: buffer to write (unused as data does not matter here
 581  *      @count: count of bytes
 582  *      @ppos: pointer to the position to write. No seeks allowed
 583  *
 584  *      A write to a watchdog device is defined as a keepalive signal. Any
 585  *      write of data will do, as we we don't define content meaning.
 586  */
 587 static ssize_t wdt_write(struct file *file, const char __user *buf,
 588                          size_t count, loff_t *ppos)
 589 {
 590         /*  Can't seek (pwrite) on this device
 591         if (ppos != &file->f_pos)
 592         return -ESPIPE;
 593         */
 594         if (count) {
 595                 wdt_ping();
 596                 return 1;
 597         }
 598         return 0;
 599 }
 600
 601 static ssize_t wdt_read(struct file *file, char __user *buf,
 602                         size_t count, loff_t *ppos)
 603 {
 604         return 0;
 605 }
 606
 607 /**
 608  *      wdt_ioctl:
 609  *      @inode: inode of the device
 610  *      @file: file handle to the device
 611  *      @cmd: watchdog command
 612  *      @arg: argument pointer
 613  *
 614  *      The watchdog API defines a common set of functions for all watchdogs
 615  *      according to their available features. We only actually usefully support
 616  *      querying capabilities and current status.
 617  */
 618 static int wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 619                      unsigned long arg)
 620 {
 621         int new_margin, rv;
 622         static struct watchdog_info ident = {
 623                 .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 624                         WDIOF_SETTIMEOUT,
 625                 .firmware_version = 1,
 626                 .identity = "M41T80 WTD"
 627         };
 628
 629         switch (cmd) {
 630         case WDIOC_GETSUPPORT:
 631                 return copy_to_user((struct watchdog_info __user *)arg, &ident,
 632                                     sizeof(ident)) ? -EFAULT : 0;
 633
 634         case WDIOC_GETSTATUS:
 635         case WDIOC_GETBOOTSTATUS:
 636                 return put_user(boot_flag, (int __user *)arg);
 637         case WDIOC_KEEPALIVE:
 638                 wdt_ping();
 639                 return 0;
 640         case WDIOC_SETTIMEOUT:
 641                 if (get_user(new_margin, (int __user *)arg))
 642                         return -EFAULT;
 643                 /* Arbitrary, can't find the card's limits */
 644                 if (new_margin < 1 || new_margin > 124)
 645                         return -EINVAL;
 646                 wdt_margin = new_margin;
 647                 wdt_ping();
 648                 /* Fall */
 649         case WDIOC_GETTIMEOUT:
 650                 return put_user(wdt_margin, (int __user *)arg);
 651
 652         case WDIOC_SETOPTIONS:
 653                 if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 654                         return -EFAULT;
 655
 656                 if (rv & WDIOS_DISABLECARD) {
 657                         pr_info("rtc-m41t80: disable watchdog\n");
 658                         wdt_disable();
 659                 }
 660
 661                 if (rv & WDIOS_ENABLECARD) {
 662                         pr_info("rtc-m41t80: enable watchdog\n");
 663                         wdt_ping();
 664                 }
 665
 666                 return -EINVAL;
 667         }
 668         return -ENOTTY;
 669 }
 670
 671 /**
 672  *      wdt_open:
 673  *      @inode: inode of device
 674  *      @file: file handle to device
 675  *
 676  */
 677 static int wdt_open(struct inode *inode, struct file *file)
 678 {
 679         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
 680                 lock_kernel();
 681                 if (test_and_set_bit(0, &wdt_is_open)) {
 682                         unlock_kernel();
 683                         return -EBUSY;
 684                 }
 685                 /*
 686                  *      Activate
 687                  */
 688                 wdt_is_open = 1;
 689                 unlock_kernel();
 690                 return 0;
 691         }
 692         return -ENODEV;
 693 }
 694
 695 /**
 696  *      wdt_close:
 697  *      @inode: inode to board
 698  *      @file: file handle to board
 699  *
 700  */
 701 static int wdt_release(struct inode *inode, struct file *file)
 702 {
 703         if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
 704                 clear_bit(0, &wdt_is_open);
 705         return 0;
 706 }
 707
 708 /**
 709  *      notify_sys:
 710  *      @this: our notifier block
 711  *      @code: the event being reported
 712  *      @unused: unused
 713  *
 714  *      Our notifier is called on system shutdowns. We want to turn the card
 715  *      off at reboot otherwise the machine will reboot again during memory
 716  *      test or worse yet during the following fsck. This would suck, in fact
 717  *      trust me - if it happens it does suck.
 718  */
 719 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 720                           void *unused)
 721 {
 722         if (code == SYS_DOWN || code == SYS_HALT)
 723                 /* Disable Watchdog */
 724                 wdt_disable();
 725         return NOTIFY_DONE;
 726 }
 727
 728 static const struct file_operations wdt_fops = {
 729         .owner  = THIS_MODULE,
 730         .read   = wdt_read,
 731         .ioctl  = wdt_ioctl,
 732         .write  = wdt_write,
 733         .open   = wdt_open,
 734         .release = wdt_release,
 735 };
 736
 737 static struct miscdevice wdt_dev = {
 738         .minor = WATCHDOG_MINOR,
 739         .name = "watchdog",
 740         .fops = &wdt_fops,
 741 };
 742
 743 /*
 744  *      The WDT card needs to learn about soft shutdowns in order to
 745  *      turn the timebomb registers off.
 746  */
 747 static struct notifier_block wdt_notifier = {
 748         .notifier_call = wdt_notify_sys,
 749 };
 750 #endif /* CONFIG_RTC_DRV_M41T80_WDT */
 751
 752 /*
 753  *****************************************************************************
 754  *
 755  *      Driver Interface
 756  *
 757  *****************************************************************************
 758  */
 759 static int m41t80_probe(struct i2c_client *client,
 760                         const struct i2c_device_id *id)
 761 {
 762         int rc = 0;
 763         struct rtc_device *rtc = NULL;
 764         struct rtc_time tm;
 765         struct m41t80_data *clientdata = NULL;
 766
 767         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
 768                                      | I2C_FUNC_SMBUS_BYTE_DATA)) {
 769                 rc = -ENODEV;
 770                 goto exit;
 771         }
 772
 773         dev_info(&client->dev,
 774                  "chip found, driver version " DRV_VERSION "\n");
 775
 776         clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
 777         if (!clientdata) {
 778                 rc = -ENOMEM;
 779                 goto exit;
 780         }
 781
 782         rtc = rtc_device_register(client->name, &client->dev,
 783                                   &m41t80_rtc_ops, THIS_MODULE);
 784         if (IS_ERR(rtc)) {
 785                 rc = PTR_ERR(rtc);
 786                 rtc = NULL;
 787                 goto exit;
 788         }
 789
 790         clientdata->rtc = rtc;
 791         clientdata->features = id->driver_data;
 792         i2c_set_clientdata(client, clientdata);
 793
 794         /* Make sure HT (Halt Update) bit is cleared */
 795         rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 796         if (rc < 0)
 797                 goto ht_err;
 798
 799         if (rc & M41T80_ALHOUR_HT) {
 800                 if (clientdata->features & M41T80_FEATURE_HT) {
 801                         m41t80_get_datetime(client, &tm);
 802                         dev_info(&client->dev, "HT bit was set!\n");
 803                         dev_info(&client->dev,
 804                                  "Power Down at "
 805                                  "%04i-%02i-%02i %02i:%02i:%02i\n",
 806                                  tm.tm_year + 1900,
 807                                  tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
 808                                  tm.tm_min, tm.tm_sec);
 809                 }
 810                 if (i2c_smbus_write_byte_data(client,
 811                                               M41T80_REG_ALARM_HOUR,
 812                                               rc & ~M41T80_ALHOUR_HT) < 0)
 813                         goto ht_err;
 814         }
 815
 816         /* Make sure ST (stop) bit is cleared */
 817         rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 818         if (rc < 0)
 819                 goto st_err;
 820
 821         if (rc & M41T80_SEC_ST) {
 822                 if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 823                                               rc & ~M41T80_SEC_ST) < 0)
 824                         goto st_err;
 825         }
 826
 827         rc = m41t80_sysfs_register(&client->dev);
 828         if (rc)
 829                 goto exit;
 830
 831 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 832         if (clientdata->features & M41T80_FEATURE_HT) {
 833                 save_client = client;
 834                 rc = misc_register(&wdt_dev);
 835                 if (rc)
 836                         goto exit;
 837                 rc = register_reboot_notifier(&wdt_notifier);
 838                 if (rc) {
 839                         misc_deregister(&wdt_dev);
 840                         goto exit;
 841                 }
 842         }
 843 #endif
 844         return 0;
 845
 846 st_err:
 847         rc = -EIO;
 848         dev_err(&client->dev, "Can't clear ST bit\n");
 849         goto exit;
 850 ht_err:
 851         rc = -EIO;
 852         dev_err(&client->dev, "Can't clear HT bit\n");
 853         goto exit;
 854
 855 exit:
 856         if (rtc)
 857                 rtc_device_unregister(rtc);
 858         kfree(clientdata);
 859         return rc;
 860 }
 861
 862 static int m41t80_remove(struct i2c_client *client)
 863 {
 864         struct m41t80_data *clientdata = i2c_get_clientdata(client);
 865         struct rtc_device *rtc = clientdata->rtc;
 866
 867 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 868         if (clientdata->features & M41T80_FEATURE_HT) {
 869                 misc_deregister(&wdt_dev);
 870                 unregister_reboot_notifier(&wdt_notifier);
 871         }
 872 #endif
 873         if (rtc)
 874                 rtc_device_unregister(rtc);
 875         kfree(clientdata);
 876
 877         return 0;
 878 }
 879
 880 static struct i2c_driver m41t80_driver = {
 881         .driver = {
 882                 .name = "rtc-m41t80",
 883         },
 884         .probe = m41t80_probe,
 885         .remove = m41t80_remove,
 886         .id_table = m41t80_id,
 887 };
 888
 889 static int __init m41t80_rtc_init(void)
 890 {
 891         return i2c_add_driver(&m41t80_driver);
 892 }
 893
 894 static void __exit m41t80_rtc_exit(void)
 895 {
 896         i2c_del_driver(&m41t80_driver);
 897 }
 898
 899 MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
 900 MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
 901 MODULE_LICENSE("GPL");
 902 MODULE_VERSION(DRV_VERSION);
 903
 904 module_init(m41t80_rtc_init);
 905 module_exit(m41t80_rtc_exit);