linux/drivers/rtc/rtc-m41t80.c
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   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
  72static 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};
  86MODULE_DEVICE_TABLE(i2c, m41t80_id);
  87
  88static const __maybe_unused 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};
 144MODULE_DEVICE_TABLE(of, m41t80_of_match);
 145
 146struct 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
 157static 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        unsigned long events = 0;
 162        int flags, flags_afe;
 163
 164        rtc_lock(m41t80->rtc);
 165
 166        flags_afe = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 167        if (flags_afe < 0) {
 168                rtc_unlock(m41t80->rtc);
 169                return IRQ_NONE;
 170        }
 171
 172        flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 173        if (flags <= 0) {
 174                rtc_unlock(m41t80->rtc);
 175                return IRQ_NONE;
 176        }
 177
 178        if (flags & M41T80_FLAGS_AF) {
 179                flags &= ~M41T80_FLAGS_AF;
 180                flags_afe &= ~M41T80_ALMON_AFE;
 181                events |= RTC_AF;
 182        }
 183
 184        if (events) {
 185                rtc_update_irq(m41t80->rtc, 1, events);
 186                i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS, flags);
 187                i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 188                                          flags_afe);
 189        }
 190
 191        rtc_unlock(m41t80->rtc);
 192
 193        return IRQ_HANDLED;
 194}
 195
 196static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
 197{
 198        struct i2c_client *client = to_i2c_client(dev);
 199        unsigned char buf[8];
 200        int err, flags;
 201
 202        flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 203        if (flags < 0)
 204                return flags;
 205
 206        if (flags & M41T80_FLAGS_OF) {
 207                dev_err(&client->dev, "Oscillator failure, data is invalid.\n");
 208                return -EINVAL;
 209        }
 210
 211        err = i2c_smbus_read_i2c_block_data(client, M41T80_REG_SSEC,
 212                                            sizeof(buf), buf);
 213        if (err < 0) {
 214                dev_err(&client->dev, "Unable to read date\n");
 215                return err;
 216        }
 217
 218        tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
 219        tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
 220        tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
 221        tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
 222        tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
 223        tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
 224
 225        /* assume 20YY not 19YY, and ignore the Century Bit */
 226        tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
 227        return 0;
 228}
 229
 230static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
 231{
 232        struct i2c_client *client = to_i2c_client(dev);
 233        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 234        unsigned char buf[8];
 235        int err, flags;
 236
 237        buf[M41T80_REG_SSEC] = 0;
 238        buf[M41T80_REG_SEC] = bin2bcd(tm->tm_sec);
 239        buf[M41T80_REG_MIN] = bin2bcd(tm->tm_min);
 240        buf[M41T80_REG_HOUR] = bin2bcd(tm->tm_hour);
 241        buf[M41T80_REG_DAY] = bin2bcd(tm->tm_mday);
 242        buf[M41T80_REG_MON] = bin2bcd(tm->tm_mon + 1);
 243        buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100);
 244        buf[M41T80_REG_WDAY] = tm->tm_wday;
 245
 246        /* If the square wave output is controlled in the weekday register */
 247        if (clientdata->features & M41T80_FEATURE_SQ_ALT) {
 248                int val;
 249
 250                val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY);
 251                if (val < 0)
 252                        return val;
 253
 254                buf[M41T80_REG_WDAY] |= (val & 0xf0);
 255        }
 256
 257        err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC,
 258                                             sizeof(buf), buf);
 259        if (err < 0) {
 260                dev_err(&client->dev, "Unable to write to date registers\n");
 261                return err;
 262        }
 263
 264        /* Clear the OF bit of Flags Register */
 265        flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 266        if (flags < 0)
 267                return flags;
 268
 269        err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 270                                        flags & ~M41T80_FLAGS_OF);
 271        if (err < 0) {
 272                dev_err(&client->dev, "Unable to write flags register\n");
 273                return err;
 274        }
 275
 276        return err;
 277}
 278
 279static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
 280{
 281        struct i2c_client *client = to_i2c_client(dev);
 282        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 283        int reg;
 284
 285        if (clientdata->features & M41T80_FEATURE_BL) {
 286                reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 287                if (reg < 0)
 288                        return reg;
 289                seq_printf(seq, "battery\t\t: %s\n",
 290                           (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
 291        }
 292        return 0;
 293}
 294
 295static int m41t80_alarm_irq_enable(struct device *dev, unsigned int enabled)
 296{
 297        struct i2c_client *client = to_i2c_client(dev);
 298        int flags, retval;
 299
 300        flags = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 301        if (flags < 0)
 302                return flags;
 303
 304        if (enabled)
 305                flags |= M41T80_ALMON_AFE;
 306        else
 307                flags &= ~M41T80_ALMON_AFE;
 308
 309        retval = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, flags);
 310        if (retval < 0) {
 311                dev_err(dev, "Unable to enable alarm IRQ %d\n", retval);
 312                return retval;
 313        }
 314        return 0;
 315}
 316
 317static int m41t80_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 318{
 319        struct i2c_client *client = to_i2c_client(dev);
 320        u8 alarmvals[5];
 321        int ret, err;
 322
 323        alarmvals[0] = bin2bcd(alrm->time.tm_mon + 1);
 324        alarmvals[1] = bin2bcd(alrm->time.tm_mday);
 325        alarmvals[2] = bin2bcd(alrm->time.tm_hour);
 326        alarmvals[3] = bin2bcd(alrm->time.tm_min);
 327        alarmvals[4] = bin2bcd(alrm->time.tm_sec);
 328
 329        /* Clear AF and AFE flags */
 330        ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 331        if (ret < 0)
 332                return ret;
 333        err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 334                                        ret & ~(M41T80_ALMON_AFE));
 335        if (err < 0) {
 336                dev_err(dev, "Unable to clear AFE bit\n");
 337                return err;
 338        }
 339
 340        /* Keep SQWE bit value */
 341        alarmvals[0] |= (ret & M41T80_ALMON_SQWE);
 342
 343        ret = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 344        if (ret < 0)
 345                return ret;
 346
 347        err = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
 348                                        ret & ~(M41T80_FLAGS_AF));
 349        if (err < 0) {
 350                dev_err(dev, "Unable to clear AF bit\n");
 351                return err;
 352        }
 353
 354        /* Write the alarm */
 355        err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_ALARM_MON,
 356                                             5, alarmvals);
 357        if (err)
 358                return err;
 359
 360        /* Enable the alarm interrupt */
 361        if (alrm->enabled) {
 362                alarmvals[0] |= M41T80_ALMON_AFE;
 363                err = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 364                                                alarmvals[0]);
 365                if (err)
 366                        return err;
 367        }
 368
 369        return 0;
 370}
 371
 372static int m41t80_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 373{
 374        struct i2c_client *client = to_i2c_client(dev);
 375        u8 alarmvals[5];
 376        int flags, ret;
 377
 378        ret = i2c_smbus_read_i2c_block_data(client, M41T80_REG_ALARM_MON,
 379                                            5, alarmvals);
 380        if (ret != 5)
 381                return ret < 0 ? ret : -EIO;
 382
 383        flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
 384        if (flags < 0)
 385                return flags;
 386
 387        alrm->time.tm_sec  = bcd2bin(alarmvals[4] & 0x7f);
 388        alrm->time.tm_min  = bcd2bin(alarmvals[3] & 0x7f);
 389        alrm->time.tm_hour = bcd2bin(alarmvals[2] & 0x3f);
 390        alrm->time.tm_mday = bcd2bin(alarmvals[1] & 0x3f);
 391        alrm->time.tm_mon  = bcd2bin(alarmvals[0] & 0x3f) - 1;
 392
 393        alrm->enabled = !!(alarmvals[0] & M41T80_ALMON_AFE);
 394        alrm->pending = (flags & M41T80_FLAGS_AF) && alrm->enabled;
 395
 396        return 0;
 397}
 398
 399static const struct rtc_class_ops m41t80_rtc_ops = {
 400        .read_time = m41t80_rtc_read_time,
 401        .set_time = m41t80_rtc_set_time,
 402        .proc = m41t80_rtc_proc,
 403        .read_alarm = m41t80_read_alarm,
 404        .set_alarm = m41t80_set_alarm,
 405        .alarm_irq_enable = m41t80_alarm_irq_enable,
 406};
 407
 408#ifdef CONFIG_PM_SLEEP
 409static int m41t80_suspend(struct device *dev)
 410{
 411        struct i2c_client *client = to_i2c_client(dev);
 412
 413        if (client->irq >= 0 && device_may_wakeup(dev))
 414                enable_irq_wake(client->irq);
 415
 416        return 0;
 417}
 418
 419static int m41t80_resume(struct device *dev)
 420{
 421        struct i2c_client *client = to_i2c_client(dev);
 422
 423        if (client->irq >= 0 && device_may_wakeup(dev))
 424                disable_irq_wake(client->irq);
 425
 426        return 0;
 427}
 428#endif
 429
 430static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
 431
 432#ifdef CONFIG_COMMON_CLK
 433#define sqw_to_m41t80_data(_hw) container_of(_hw, struct m41t80_data, sqw)
 434
 435static unsigned long m41t80_decode_freq(int setting)
 436{
 437        return (setting == 0) ? 0 : (setting == 1) ? M41T80_SQW_MAX_FREQ :
 438                M41T80_SQW_MAX_FREQ >> setting;
 439}
 440
 441static unsigned long m41t80_get_freq(struct m41t80_data *m41t80)
 442{
 443        struct i2c_client *client = m41t80->client;
 444        int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 445                M41T80_REG_WDAY : M41T80_REG_SQW;
 446        int ret = i2c_smbus_read_byte_data(client, reg_sqw);
 447
 448        if (ret < 0)
 449                return 0;
 450        return m41t80_decode_freq(ret >> 4);
 451}
 452
 453static unsigned long m41t80_sqw_recalc_rate(struct clk_hw *hw,
 454                                            unsigned long parent_rate)
 455{
 456        return sqw_to_m41t80_data(hw)->freq;
 457}
 458
 459static long m41t80_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
 460                                  unsigned long *prate)
 461{
 462        if (rate >= M41T80_SQW_MAX_FREQ)
 463                return M41T80_SQW_MAX_FREQ;
 464        if (rate >= M41T80_SQW_MAX_FREQ / 4)
 465                return M41T80_SQW_MAX_FREQ / 4;
 466        if (!rate)
 467                return 0;
 468        return 1 << ilog2(rate);
 469}
 470
 471static int m41t80_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
 472                               unsigned long parent_rate)
 473{
 474        struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 475        struct i2c_client *client = m41t80->client;
 476        int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ?
 477                M41T80_REG_WDAY : M41T80_REG_SQW;
 478        int reg, ret, val = 0;
 479
 480        if (rate >= M41T80_SQW_MAX_FREQ)
 481                val = 1;
 482        else if (rate >= M41T80_SQW_MAX_FREQ / 4)
 483                val = 2;
 484        else if (rate)
 485                val = 15 - ilog2(rate);
 486
 487        reg = i2c_smbus_read_byte_data(client, reg_sqw);
 488        if (reg < 0)
 489                return reg;
 490
 491        reg = (reg & 0x0f) | (val << 4);
 492
 493        ret = i2c_smbus_write_byte_data(client, reg_sqw, reg);
 494        if (!ret)
 495                m41t80->freq = m41t80_decode_freq(val);
 496        return ret;
 497}
 498
 499static int m41t80_sqw_control(struct clk_hw *hw, bool enable)
 500{
 501        struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw);
 502        struct i2c_client *client = m41t80->client;
 503        int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 504
 505        if (ret < 0)
 506                return ret;
 507
 508        if (enable)
 509                ret |= M41T80_ALMON_SQWE;
 510        else
 511                ret &= ~M41T80_ALMON_SQWE;
 512
 513        ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret);
 514        if (!ret)
 515                m41t80->sqwe = enable;
 516        return ret;
 517}
 518
 519static int m41t80_sqw_prepare(struct clk_hw *hw)
 520{
 521        return m41t80_sqw_control(hw, 1);
 522}
 523
 524static void m41t80_sqw_unprepare(struct clk_hw *hw)
 525{
 526        m41t80_sqw_control(hw, 0);
 527}
 528
 529static int m41t80_sqw_is_prepared(struct clk_hw *hw)
 530{
 531        return sqw_to_m41t80_data(hw)->sqwe;
 532}
 533
 534static const struct clk_ops m41t80_sqw_ops = {
 535        .prepare = m41t80_sqw_prepare,
 536        .unprepare = m41t80_sqw_unprepare,
 537        .is_prepared = m41t80_sqw_is_prepared,
 538        .recalc_rate = m41t80_sqw_recalc_rate,
 539        .round_rate = m41t80_sqw_round_rate,
 540        .set_rate = m41t80_sqw_set_rate,
 541};
 542
 543static struct clk *m41t80_sqw_register_clk(struct m41t80_data *m41t80)
 544{
 545        struct i2c_client *client = m41t80->client;
 546        struct device_node *node = client->dev.of_node;
 547        struct device_node *fixed_clock;
 548        struct clk *clk;
 549        struct clk_init_data init;
 550        int ret;
 551
 552        fixed_clock = of_get_child_by_name(node, "clock");
 553        if (fixed_clock) {
 554                /*
 555                 * skip registering square wave clock when a fixed
 556                 * clock has been registered. The fixed clock is
 557                 * registered automatically when being referenced.
 558                 */
 559                of_node_put(fixed_clock);
 560                return 0;
 561        }
 562
 563        /* First disable the clock */
 564        ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
 565        if (ret < 0)
 566                return ERR_PTR(ret);
 567        ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
 568                                        ret & ~(M41T80_ALMON_SQWE));
 569        if (ret < 0)
 570                return ERR_PTR(ret);
 571
 572        init.name = "m41t80-sqw";
 573        init.ops = &m41t80_sqw_ops;
 574        init.flags = 0;
 575        init.parent_names = NULL;
 576        init.num_parents = 0;
 577        m41t80->sqw.init = &init;
 578        m41t80->freq = m41t80_get_freq(m41t80);
 579
 580        /* optional override of the clockname */
 581        of_property_read_string(node, "clock-output-names", &init.name);
 582
 583        /* register the clock */
 584        clk = clk_register(&client->dev, &m41t80->sqw);
 585        if (!IS_ERR(clk))
 586                of_clk_add_provider(node, of_clk_src_simple_get, clk);
 587
 588        return clk;
 589}
 590#endif
 591
 592#ifdef CONFIG_RTC_DRV_M41T80_WDT
 593/*
 594 *****************************************************************************
 595 *
 596 * Watchdog Driver
 597 *
 598 *****************************************************************************
 599 */
 600static DEFINE_MUTEX(m41t80_rtc_mutex);
 601static struct i2c_client *save_client;
 602
 603/* Default margin */
 604#define WD_TIMO 60              /* 1..31 seconds */
 605
 606static int wdt_margin = WD_TIMO;
 607module_param(wdt_margin, int, 0);
 608MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
 609
 610static unsigned long wdt_is_open;
 611static int boot_flag;
 612
 613/**
 614 *      wdt_ping - Reload counter one with the watchdog timeout.
 615 *      We don't bother reloading the cascade counter.
 616 */
 617static void wdt_ping(void)
 618{
 619        unsigned char i2c_data[2];
 620        struct i2c_msg msgs1[1] = {
 621                {
 622                        .addr   = save_client->addr,
 623                        .flags  = 0,
 624                        .len    = 2,
 625                        .buf    = i2c_data,
 626                },
 627        };
 628        struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
 629
 630        i2c_data[0] = 0x09;             /* watchdog register */
 631
 632        if (wdt_margin > 31)
 633                i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
 634        else
 635                /*
 636                 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
 637                 */
 638                i2c_data[1] = wdt_margin << 2 | 0x82;
 639
 640        /*
 641         * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
 642         * that would be an invalid resolution.
 643         */
 644        if (clientdata->features & M41T80_FEATURE_WD)
 645                i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
 646
 647        i2c_transfer(save_client->adapter, msgs1, 1);
 648}
 649
 650/**
 651 *      wdt_disable - disables watchdog.
 652 */
 653static void wdt_disable(void)
 654{
 655        unsigned char i2c_data[2], i2c_buf[0x10];
 656        struct i2c_msg msgs0[2] = {
 657                {
 658                        .addr   = save_client->addr,
 659                        .flags  = 0,
 660                        .len    = 1,
 661                        .buf    = i2c_data,
 662                },
 663                {
 664                        .addr   = save_client->addr,
 665                        .flags  = I2C_M_RD,
 666                        .len    = 1,
 667                        .buf    = i2c_buf,
 668                },
 669        };
 670        struct i2c_msg msgs1[1] = {
 671                {
 672                        .addr   = save_client->addr,
 673                        .flags  = 0,
 674                        .len    = 2,
 675                        .buf    = i2c_data,
 676                },
 677        };
 678
 679        i2c_data[0] = 0x09;
 680        i2c_transfer(save_client->adapter, msgs0, 2);
 681
 682        i2c_data[0] = 0x09;
 683        i2c_data[1] = 0x00;
 684        i2c_transfer(save_client->adapter, msgs1, 1);
 685}
 686
 687/**
 688 *      wdt_write - write to watchdog.
 689 *      @file: file handle to the watchdog
 690 *      @buf: buffer to write (unused as data does not matter here
 691 *      @count: count of bytes
 692 *      @ppos: pointer to the position to write. No seeks allowed
 693 *
 694 *      A write to a watchdog device is defined as a keepalive signal. Any
 695 *      write of data will do, as we we don't define content meaning.
 696 */
 697static ssize_t wdt_write(struct file *file, const char __user *buf,
 698                         size_t count, loff_t *ppos)
 699{
 700        if (count) {
 701                wdt_ping();
 702                return 1;
 703        }
 704        return 0;
 705}
 706
 707static ssize_t wdt_read(struct file *file, char __user *buf,
 708                        size_t count, loff_t *ppos)
 709{
 710        return 0;
 711}
 712
 713/**
 714 *      wdt_ioctl - ioctl handler to set watchdog.
 715 *      @file: file handle to the device
 716 *      @cmd: watchdog command
 717 *      @arg: argument pointer
 718 *
 719 *      The watchdog API defines a common set of functions for all watchdogs
 720 *      according to their available features. We only actually usefully support
 721 *      querying capabilities and current status.
 722 */
 723static int wdt_ioctl(struct file *file, unsigned int cmd,
 724                     unsigned long arg)
 725{
 726        int new_margin, rv;
 727        static struct watchdog_info ident = {
 728                .options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
 729                        WDIOF_SETTIMEOUT,
 730                .firmware_version = 1,
 731                .identity = "M41T80 WTD"
 732        };
 733
 734        switch (cmd) {
 735        case WDIOC_GETSUPPORT:
 736                return copy_to_user((struct watchdog_info __user *)arg, &ident,
 737                                    sizeof(ident)) ? -EFAULT : 0;
 738
 739        case WDIOC_GETSTATUS:
 740        case WDIOC_GETBOOTSTATUS:
 741                return put_user(boot_flag, (int __user *)arg);
 742        case WDIOC_KEEPALIVE:
 743                wdt_ping();
 744                return 0;
 745        case WDIOC_SETTIMEOUT:
 746                if (get_user(new_margin, (int __user *)arg))
 747                        return -EFAULT;
 748                /* Arbitrary, can't find the card's limits */
 749                if (new_margin < 1 || new_margin > 124)
 750                        return -EINVAL;
 751                wdt_margin = new_margin;
 752                wdt_ping();
 753                fallthrough;
 754        case WDIOC_GETTIMEOUT:
 755                return put_user(wdt_margin, (int __user *)arg);
 756
 757        case WDIOC_SETOPTIONS:
 758                if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
 759                        return -EFAULT;
 760
 761                if (rv & WDIOS_DISABLECARD) {
 762                        pr_info("disable watchdog\n");
 763                        wdt_disable();
 764                }
 765
 766                if (rv & WDIOS_ENABLECARD) {
 767                        pr_info("enable watchdog\n");
 768                        wdt_ping();
 769                }
 770
 771                return -EINVAL;
 772        }
 773        return -ENOTTY;
 774}
 775
 776static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
 777                               unsigned long arg)
 778{
 779        int ret;
 780
 781        mutex_lock(&m41t80_rtc_mutex);
 782        ret = wdt_ioctl(file, cmd, arg);
 783        mutex_unlock(&m41t80_rtc_mutex);
 784
 785        return ret;
 786}
 787
 788/**
 789 *      wdt_open - open a watchdog.
 790 *      @inode: inode of device
 791 *      @file: file handle to device
 792 *
 793 */
 794static int wdt_open(struct inode *inode, struct file *file)
 795{
 796        if (iminor(inode) == WATCHDOG_MINOR) {
 797                mutex_lock(&m41t80_rtc_mutex);
 798                if (test_and_set_bit(0, &wdt_is_open)) {
 799                        mutex_unlock(&m41t80_rtc_mutex);
 800                        return -EBUSY;
 801                }
 802                /*
 803                 *      Activate
 804                 */
 805                wdt_is_open = 1;
 806                mutex_unlock(&m41t80_rtc_mutex);
 807                return stream_open(inode, file);
 808        }
 809        return -ENODEV;
 810}
 811
 812/**
 813 *      wdt_release - release a watchdog.
 814 *      @inode: inode to board
 815 *      @file: file handle to board
 816 *
 817 */
 818static int wdt_release(struct inode *inode, struct file *file)
 819{
 820        if (iminor(inode) == WATCHDOG_MINOR)
 821                clear_bit(0, &wdt_is_open);
 822        return 0;
 823}
 824
 825/**
 826 *      wdt_notify_sys - notify to watchdog.
 827 *      @this: our notifier block
 828 *      @code: the event being reported
 829 *      @unused: unused
 830 *
 831 *      Our notifier is called on system shutdowns. We want to turn the card
 832 *      off at reboot otherwise the machine will reboot again during memory
 833 *      test or worse yet during the following fsck. This would suck, in fact
 834 *      trust me - if it happens it does suck.
 835 */
 836static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 837                          void *unused)
 838{
 839        if (code == SYS_DOWN || code == SYS_HALT)
 840                /* Disable Watchdog */
 841                wdt_disable();
 842        return NOTIFY_DONE;
 843}
 844
 845static const struct file_operations wdt_fops = {
 846        .owner  = THIS_MODULE,
 847        .read   = wdt_read,
 848        .unlocked_ioctl = wdt_unlocked_ioctl,
 849        .compat_ioctl = compat_ptr_ioctl,
 850        .write  = wdt_write,
 851        .open   = wdt_open,
 852        .release = wdt_release,
 853        .llseek = no_llseek,
 854};
 855
 856static struct miscdevice wdt_dev = {
 857        .minor = WATCHDOG_MINOR,
 858        .name = "watchdog",
 859        .fops = &wdt_fops,
 860};
 861
 862/*
 863 *      The WDT card needs to learn about soft shutdowns in order to
 864 *      turn the timebomb registers off.
 865 */
 866static struct notifier_block wdt_notifier = {
 867        .notifier_call = wdt_notify_sys,
 868};
 869#endif /* CONFIG_RTC_DRV_M41T80_WDT */
 870
 871/*
 872 *****************************************************************************
 873 *
 874 *      Driver Interface
 875 *
 876 *****************************************************************************
 877 */
 878
 879static int m41t80_probe(struct i2c_client *client,
 880                        const struct i2c_device_id *id)
 881{
 882        struct i2c_adapter *adapter = client->adapter;
 883        int rc = 0;
 884        struct rtc_time tm;
 885        struct m41t80_data *m41t80_data = NULL;
 886        bool wakeup_source = false;
 887
 888        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK |
 889                                     I2C_FUNC_SMBUS_BYTE_DATA)) {
 890                dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
 891                return -ENODEV;
 892        }
 893
 894        m41t80_data = devm_kzalloc(&client->dev, sizeof(*m41t80_data),
 895                                   GFP_KERNEL);
 896        if (!m41t80_data)
 897                return -ENOMEM;
 898
 899        m41t80_data->client = client;
 900        if (client->dev.of_node)
 901                m41t80_data->features = (unsigned long)
 902                        of_device_get_match_data(&client->dev);
 903        else
 904                m41t80_data->features = id->driver_data;
 905        i2c_set_clientdata(client, m41t80_data);
 906
 907        m41t80_data->rtc =  devm_rtc_allocate_device(&client->dev);
 908        if (IS_ERR(m41t80_data->rtc))
 909                return PTR_ERR(m41t80_data->rtc);
 910
 911#ifdef CONFIG_OF
 912        wakeup_source = of_property_read_bool(client->dev.of_node,
 913                                              "wakeup-source");
 914#endif
 915        if (client->irq > 0) {
 916                rc = devm_request_threaded_irq(&client->dev, client->irq,
 917                                               NULL, m41t80_handle_irq,
 918                                               IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 919                                               "m41t80", client);
 920                if (rc) {
 921                        dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
 922                        client->irq = 0;
 923                        wakeup_source = false;
 924                }
 925        }
 926        if (client->irq > 0 || wakeup_source)
 927                device_init_wakeup(&client->dev, true);
 928        else
 929                clear_bit(RTC_FEATURE_ALARM, m41t80_data->rtc->features);
 930
 931        m41t80_data->rtc->ops = &m41t80_rtc_ops;
 932        m41t80_data->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 933        m41t80_data->rtc->range_max = RTC_TIMESTAMP_END_2099;
 934
 935        if (client->irq <= 0) {
 936                /* We cannot support UIE mode if we do not have an IRQ line */
 937                m41t80_data->rtc->uie_unsupported = 1;
 938        }
 939
 940        /* Make sure HT (Halt Update) bit is cleared */
 941        rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
 942
 943        if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
 944                if (m41t80_data->features & M41T80_FEATURE_HT) {
 945                        m41t80_rtc_read_time(&client->dev, &tm);
 946                        dev_info(&client->dev, "HT bit was set!\n");
 947                        dev_info(&client->dev, "Power Down at %ptR\n", &tm);
 948                }
 949                rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
 950                                               rc & ~M41T80_ALHOUR_HT);
 951        }
 952
 953        if (rc < 0) {
 954                dev_err(&client->dev, "Can't clear HT bit\n");
 955                return rc;
 956        }
 957
 958        /* Make sure ST (stop) bit is cleared */
 959        rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
 960
 961        if (rc >= 0 && rc & M41T80_SEC_ST)
 962                rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
 963                                               rc & ~M41T80_SEC_ST);
 964        if (rc < 0) {
 965                dev_err(&client->dev, "Can't clear ST bit\n");
 966                return rc;
 967        }
 968
 969#ifdef CONFIG_RTC_DRV_M41T80_WDT
 970        if (m41t80_data->features & M41T80_FEATURE_HT) {
 971                save_client = client;
 972                rc = misc_register(&wdt_dev);
 973                if (rc)
 974                        return rc;
 975                rc = register_reboot_notifier(&wdt_notifier);
 976                if (rc) {
 977                        misc_deregister(&wdt_dev);
 978                        return rc;
 979                }
 980        }
 981#endif
 982#ifdef CONFIG_COMMON_CLK
 983        if (m41t80_data->features & M41T80_FEATURE_SQ)
 984                m41t80_sqw_register_clk(m41t80_data);
 985#endif
 986
 987        rc = devm_rtc_register_device(m41t80_data->rtc);
 988        if (rc)
 989                return rc;
 990
 991        return 0;
 992}
 993
 994static int m41t80_remove(struct i2c_client *client)
 995{
 996#ifdef CONFIG_RTC_DRV_M41T80_WDT
 997        struct m41t80_data *clientdata = i2c_get_clientdata(client);
 998
 999        if (clientdata->features & M41T80_FEATURE_HT) {
1000                misc_deregister(&wdt_dev);
1001                unregister_reboot_notifier(&wdt_notifier);
1002        }
1003#endif
1004
1005        return 0;
1006}
1007
1008static struct i2c_driver m41t80_driver = {
1009        .driver = {
1010                .name = "rtc-m41t80",
1011                .of_match_table = of_match_ptr(m41t80_of_match),
1012                .pm = &m41t80_pm,
1013        },
1014        .probe = m41t80_probe,
1015        .remove = m41t80_remove,
1016        .id_table = m41t80_id,
1017};
1018
1019module_i2c_driver(m41t80_driver);
1020
1021MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
1022MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
1023MODULE_LICENSE("GPL");
1024