linux/drivers/rtc/rtc-ds1374.c
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   1/*
   2 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
   3 *
   4 * Based on code by Randy Vinson <rvinson@mvista.com>,
   5 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
   6 *
   7 * Copyright (C) 2006-2007 Freescale Semiconductor
   8 *
   9 * 2005 (c) MontaVista Software, Inc. This file is licensed under
  10 * the terms of the GNU General Public License version 2. This program
  11 * is licensed "as is" without any warranty of any kind, whether express
  12 * or implied.
  13 */
  14/*
  15 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  16 * recommened in .../Documentation/i2c/writing-clients section
  17 * "Sending and receiving", using SMBus level communication is preferred.
  18 */
  19
  20#include <linux/kernel.h>
  21#include <linux/module.h>
  22#include <linux/interrupt.h>
  23#include <linux/i2c.h>
  24#include <linux/rtc.h>
  25#include <linux/bcd.h>
  26#include <linux/workqueue.h>
  27#include <linux/slab.h>
  28#include <linux/pm.h>
  29
  30#define DS1374_REG_TOD0         0x00 /* Time of Day */
  31#define DS1374_REG_TOD1         0x01
  32#define DS1374_REG_TOD2         0x02
  33#define DS1374_REG_TOD3         0x03
  34#define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
  35#define DS1374_REG_WDALM1       0x05
  36#define DS1374_REG_WDALM2       0x06
  37#define DS1374_REG_CR           0x07 /* Control */
  38#define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
  39#define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
  40#define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
  41#define DS1374_REG_SR           0x08 /* Status */
  42#define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
  43#define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
  44#define DS1374_REG_TCR          0x09 /* Trickle Charge */
  45
  46static const struct i2c_device_id ds1374_id[] = {
  47        { "ds1374", 0 },
  48        { }
  49};
  50MODULE_DEVICE_TABLE(i2c, ds1374_id);
  51
  52struct ds1374 {
  53        struct i2c_client *client;
  54        struct rtc_device *rtc;
  55        struct work_struct work;
  56
  57        /* The mutex protects alarm operations, and prevents a race
  58         * between the enable_irq() in the workqueue and the free_irq()
  59         * in the remove function.
  60         */
  61        struct mutex mutex;
  62        int exiting;
  63};
  64
  65static struct i2c_driver ds1374_driver;
  66
  67static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
  68                           int reg, int nbytes)
  69{
  70        u8 buf[4];
  71        int ret;
  72        int i;
  73
  74        if (nbytes > 4) {
  75                WARN_ON(1);
  76                return -EINVAL;
  77        }
  78
  79        ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
  80
  81        if (ret < 0)
  82                return ret;
  83        if (ret < nbytes)
  84                return -EIO;
  85
  86        for (i = nbytes - 1, *time = 0; i >= 0; i--)
  87                *time = (*time << 8) | buf[i];
  88
  89        return 0;
  90}
  91
  92static int ds1374_write_rtc(struct i2c_client *client, u32 time,
  93                            int reg, int nbytes)
  94{
  95        u8 buf[4];
  96        int i;
  97
  98        if (nbytes > 4) {
  99                WARN_ON(1);
 100                return -EINVAL;
 101        }
 102
 103        for (i = 0; i < nbytes; i++) {
 104                buf[i] = time & 0xff;
 105                time >>= 8;
 106        }
 107
 108        return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
 109}
 110
 111static int ds1374_check_rtc_status(struct i2c_client *client)
 112{
 113        int ret = 0;
 114        int control, stat;
 115
 116        stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 117        if (stat < 0)
 118                return stat;
 119
 120        if (stat & DS1374_REG_SR_OSF)
 121                dev_warn(&client->dev,
 122                         "oscillator discontinuity flagged, time unreliable\n");
 123
 124        stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
 125
 126        ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 127        if (ret < 0)
 128                return ret;
 129
 130        /* If the alarm is pending, clear it before requesting
 131         * the interrupt, so an interrupt event isn't reported
 132         * before everything is initialized.
 133         */
 134
 135        control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 136        if (control < 0)
 137                return control;
 138
 139        control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 140        return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 141}
 142
 143static int ds1374_read_time(struct device *dev, struct rtc_time *time)
 144{
 145        struct i2c_client *client = to_i2c_client(dev);
 146        u32 itime;
 147        int ret;
 148
 149        ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
 150        if (!ret)
 151                rtc_time_to_tm(itime, time);
 152
 153        return ret;
 154}
 155
 156static int ds1374_set_time(struct device *dev, struct rtc_time *time)
 157{
 158        struct i2c_client *client = to_i2c_client(dev);
 159        unsigned long itime;
 160
 161        rtc_tm_to_time(time, &itime);
 162        return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
 163}
 164
 165/* The ds1374 has a decrementer for an alarm, rather than a comparator.
 166 * If the time of day is changed, then the alarm will need to be
 167 * reset.
 168 */
 169static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 170{
 171        struct i2c_client *client = to_i2c_client(dev);
 172        struct ds1374 *ds1374 = i2c_get_clientdata(client);
 173        u32 now, cur_alarm;
 174        int cr, sr;
 175        int ret = 0;
 176
 177        if (client->irq <= 0)
 178                return -EINVAL;
 179
 180        mutex_lock(&ds1374->mutex);
 181
 182        cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 183        if (ret < 0)
 184                goto out;
 185
 186        sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 187        if (ret < 0)
 188                goto out;
 189
 190        ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
 191        if (ret)
 192                goto out;
 193
 194        ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
 195        if (ret)
 196                goto out;
 197
 198        rtc_time_to_tm(now + cur_alarm, &alarm->time);
 199        alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
 200        alarm->pending = !!(sr & DS1374_REG_SR_AF);
 201
 202out:
 203        mutex_unlock(&ds1374->mutex);
 204        return ret;
 205}
 206
 207static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 208{
 209        struct i2c_client *client = to_i2c_client(dev);
 210        struct ds1374 *ds1374 = i2c_get_clientdata(client);
 211        struct rtc_time now;
 212        unsigned long new_alarm, itime;
 213        int cr;
 214        int ret = 0;
 215
 216        if (client->irq <= 0)
 217                return -EINVAL;
 218
 219        ret = ds1374_read_time(dev, &now);
 220        if (ret < 0)
 221                return ret;
 222
 223        rtc_tm_to_time(&alarm->time, &new_alarm);
 224        rtc_tm_to_time(&now, &itime);
 225
 226        /* This can happen due to races, in addition to dates that are
 227         * truly in the past.  To avoid requiring the caller to check for
 228         * races, dates in the past are assumed to be in the recent past
 229         * (i.e. not something that we'd rather the caller know about via
 230         * an error), and the alarm is set to go off as soon as possible.
 231         */
 232        if (time_before_eq(new_alarm, itime))
 233                new_alarm = 1;
 234        else
 235                new_alarm -= itime;
 236
 237        mutex_lock(&ds1374->mutex);
 238
 239        ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 240        if (ret < 0)
 241                goto out;
 242
 243        /* Disable any existing alarm before setting the new one
 244         * (or lack thereof). */
 245        cr &= ~DS1374_REG_CR_WACE;
 246
 247        ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 248        if (ret < 0)
 249                goto out;
 250
 251        ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
 252        if (ret)
 253                goto out;
 254
 255        if (alarm->enabled) {
 256                cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 257                cr &= ~DS1374_REG_CR_WDALM;
 258
 259                ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 260        }
 261
 262out:
 263        mutex_unlock(&ds1374->mutex);
 264        return ret;
 265}
 266
 267static irqreturn_t ds1374_irq(int irq, void *dev_id)
 268{
 269        struct i2c_client *client = dev_id;
 270        struct ds1374 *ds1374 = i2c_get_clientdata(client);
 271
 272        disable_irq_nosync(irq);
 273        schedule_work(&ds1374->work);
 274        return IRQ_HANDLED;
 275}
 276
 277static void ds1374_work(struct work_struct *work)
 278{
 279        struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
 280        struct i2c_client *client = ds1374->client;
 281        int stat, control;
 282
 283        mutex_lock(&ds1374->mutex);
 284
 285        stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 286        if (stat < 0)
 287                goto unlock;
 288
 289        if (stat & DS1374_REG_SR_AF) {
 290                stat &= ~DS1374_REG_SR_AF;
 291                i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 292
 293                control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 294                if (control < 0)
 295                        goto out;
 296
 297                control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 298                i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 299
 300                rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
 301        }
 302
 303out:
 304        if (!ds1374->exiting)
 305                enable_irq(client->irq);
 306unlock:
 307        mutex_unlock(&ds1374->mutex);
 308}
 309
 310static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
 311{
 312        struct i2c_client *client = to_i2c_client(dev);
 313        struct ds1374 *ds1374 = i2c_get_clientdata(client);
 314        int ret;
 315
 316        mutex_lock(&ds1374->mutex);
 317
 318        ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 319        if (ret < 0)
 320                goto out;
 321
 322        if (enabled) {
 323                ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 324                ret &= ~DS1374_REG_CR_WDALM;
 325        } else {
 326                ret &= ~DS1374_REG_CR_WACE;
 327        }
 328        ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
 329
 330out:
 331        mutex_unlock(&ds1374->mutex);
 332        return ret;
 333}
 334
 335static const struct rtc_class_ops ds1374_rtc_ops = {
 336        .read_time = ds1374_read_time,
 337        .set_time = ds1374_set_time,
 338        .read_alarm = ds1374_read_alarm,
 339        .set_alarm = ds1374_set_alarm,
 340        .alarm_irq_enable = ds1374_alarm_irq_enable,
 341};
 342
 343static int ds1374_probe(struct i2c_client *client,
 344                        const struct i2c_device_id *id)
 345{
 346        struct ds1374 *ds1374;
 347        int ret;
 348
 349        ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
 350        if (!ds1374)
 351                return -ENOMEM;
 352
 353        ds1374->client = client;
 354        i2c_set_clientdata(client, ds1374);
 355
 356        INIT_WORK(&ds1374->work, ds1374_work);
 357        mutex_init(&ds1374->mutex);
 358
 359        ret = ds1374_check_rtc_status(client);
 360        if (ret)
 361                return ret;
 362
 363        if (client->irq > 0) {
 364                ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
 365                                        "ds1374", client);
 366                if (ret) {
 367                        dev_err(&client->dev, "unable to request IRQ\n");
 368                        return ret;
 369                }
 370
 371                device_set_wakeup_capable(&client->dev, 1);
 372        }
 373
 374        ds1374->rtc = devm_rtc_device_register(&client->dev, client->name,
 375                                                &ds1374_rtc_ops, THIS_MODULE);
 376        if (IS_ERR(ds1374->rtc)) {
 377                dev_err(&client->dev, "unable to register the class device\n");
 378                return PTR_ERR(ds1374->rtc);
 379        }
 380
 381        return 0;
 382}
 383
 384static int ds1374_remove(struct i2c_client *client)
 385{
 386        struct ds1374 *ds1374 = i2c_get_clientdata(client);
 387
 388        if (client->irq > 0) {
 389                mutex_lock(&ds1374->mutex);
 390                ds1374->exiting = 1;
 391                mutex_unlock(&ds1374->mutex);
 392
 393                devm_free_irq(&client->dev, client->irq, client);
 394                cancel_work_sync(&ds1374->work);
 395        }
 396
 397        return 0;
 398}
 399
 400#ifdef CONFIG_PM_SLEEP
 401static int ds1374_suspend(struct device *dev)
 402{
 403        struct i2c_client *client = to_i2c_client(dev);
 404
 405        if (client->irq >= 0 && device_may_wakeup(&client->dev))
 406                enable_irq_wake(client->irq);
 407        return 0;
 408}
 409
 410static int ds1374_resume(struct device *dev)
 411{
 412        struct i2c_client *client = to_i2c_client(dev);
 413
 414        if (client->irq >= 0 && device_may_wakeup(&client->dev))
 415                disable_irq_wake(client->irq);
 416        return 0;
 417}
 418#endif
 419
 420static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
 421
 422static struct i2c_driver ds1374_driver = {
 423        .driver = {
 424                .name = "rtc-ds1374",
 425                .owner = THIS_MODULE,
 426                .pm = &ds1374_pm,
 427        },
 428        .probe = ds1374_probe,
 429        .remove = ds1374_remove,
 430        .id_table = ds1374_id,
 431};
 432
 433module_i2c_driver(ds1374_driver);
 434
 435MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
 436MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
 437MODULE_LICENSE("GPL");
 438
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