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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C4 *5 * Based on code by Randy Vinson <rvinson@mvista.com>,6 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.7 *8 * Copyright (C) 2014 Rose Technology9 * Copyright (C) 2006-2007 Freescale Semiconductor10 * Copyright (c) 2005 MontaVista Software, Inc.11 */12/*13 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as14 * recommended in .../Documentation/i2c/writing-clients.rst section15 * "Sending and receiving", using SMBus level communication is preferred.16 */17 18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt19 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#ifdef CONFIG_RTC_DRV_DS1374_WDT30#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#endif36 37#define DS1374_REG_TOD0 0x00 /* Time of Day */38#define DS1374_REG_TOD1 0x0139#define DS1374_REG_TOD2 0x0240#define DS1374_REG_TOD3 0x0341#define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */42#define DS1374_REG_WDALM1 0x0543#define DS1374_REG_WDALM2 0x0644#define DS1374_REG_CR 0x07 /* Control */45#define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */46#define DS1374_REG_CR_WDSTR 0x08 /* 1=INT, 0=RST */47#define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */48#define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */49#define DS1374_REG_SR 0x08 /* Status */50#define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */51#define DS1374_REG_SR_AF 0x01 /* Alarm Flag */52#define DS1374_REG_TCR 0x09 /* Trickle Charge */53 54static const struct i2c_device_id ds1374_id[] = {55 { "ds1374" },56 { }57};58MODULE_DEVICE_TABLE(i2c, ds1374_id);59 60#ifdef CONFIG_OF61static const struct of_device_id ds1374_of_match[] = {62 { .compatible = "dallas,ds1374" },63 { }64};65MODULE_DEVICE_TABLE(of, ds1374_of_match);66#endif67 68struct ds1374 {69 struct i2c_client *client;70 struct rtc_device *rtc;71 struct work_struct work;72#ifdef CONFIG_RTC_DRV_DS1374_WDT73 struct watchdog_device wdt;74#endif75 /* The mutex protects alarm operations, and prevents a race76 * between the enable_irq() in the workqueue and the free_irq()77 * in the remove function.78 */79 struct mutex mutex;80 int exiting;81};82 83static struct i2c_driver ds1374_driver;84 85static int ds1374_read_rtc(struct i2c_client *client, u32 *time,86 int reg, int nbytes)87{88 u8 buf[4];89 int ret;90 int i;91 92 if (WARN_ON(nbytes > 4))93 return -EINVAL;94 95 ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);96 97 if (ret < 0)98 return ret;99 if (ret < nbytes)100 return -EIO;101 102 for (i = nbytes - 1, *time = 0; i >= 0; i--)103 *time = (*time << 8) | buf[i];104 105 return 0;106}107 108static int ds1374_write_rtc(struct i2c_client *client, u32 time,109 int reg, int nbytes)110{111 u8 buf[4];112 int i;113 114 if (nbytes > 4) {115 WARN_ON(1);116 return -EINVAL;117 }118 119 for (i = 0; i < nbytes; i++) {120 buf[i] = time & 0xff;121 time >>= 8;122 }123 124 return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);125}126 127static int ds1374_check_rtc_status(struct i2c_client *client)128{129 int ret = 0;130 int control, stat;131 132 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);133 if (stat < 0)134 return stat;135 136 if (stat & DS1374_REG_SR_OSF)137 dev_warn(&client->dev,138 "oscillator discontinuity flagged, time unreliable\n");139 140 stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);141 142 ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);143 if (ret < 0)144 return ret;145 146 /* If the alarm is pending, clear it before requesting147 * the interrupt, so an interrupt event isn't reported148 * before everything is initialized.149 */150 151 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);152 if (control < 0)153 return control;154 155 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);156 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);157}158 159static int ds1374_read_time(struct device *dev, struct rtc_time *time)160{161 struct i2c_client *client = to_i2c_client(dev);162 u32 itime;163 int ret;164 165 ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);166 if (!ret)167 rtc_time64_to_tm(itime, time);168 169 return ret;170}171 172static int ds1374_set_time(struct device *dev, struct rtc_time *time)173{174 struct i2c_client *client = to_i2c_client(dev);175 unsigned long itime = rtc_tm_to_time64(time);176 177 return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);178}179 180#ifndef CONFIG_RTC_DRV_DS1374_WDT181/* The ds1374 has a decrementer for an alarm, rather than a comparator.182 * If the time of day is changed, then the alarm will need to be183 * reset.184 */185static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)186{187 struct i2c_client *client = to_i2c_client(dev);188 struct ds1374 *ds1374 = i2c_get_clientdata(client);189 u32 now, cur_alarm;190 int cr, sr;191 int ret = 0;192 193 if (client->irq <= 0)194 return -EINVAL;195 196 mutex_lock(&ds1374->mutex);197 198 cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);199 if (ret < 0)200 goto out;201 202 sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);203 if (ret < 0)204 goto out;205 206 ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);207 if (ret)208 goto out;209 210 ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);211 if (ret)212 goto out;213 214 rtc_time64_to_tm(now + cur_alarm, &alarm->time);215 alarm->enabled = !!(cr & DS1374_REG_CR_WACE);216 alarm->pending = !!(sr & DS1374_REG_SR_AF);217 218out:219 mutex_unlock(&ds1374->mutex);220 return ret;221}222 223static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)224{225 struct i2c_client *client = to_i2c_client(dev);226 struct ds1374 *ds1374 = i2c_get_clientdata(client);227 struct rtc_time now;228 unsigned long new_alarm, itime;229 int cr;230 int ret = 0;231 232 if (client->irq <= 0)233 return -EINVAL;234 235 ret = ds1374_read_time(dev, &now);236 if (ret < 0)237 return ret;238 239 new_alarm = rtc_tm_to_time64(&alarm->time);240 itime = rtc_tm_to_time64(&now);241 242 /* This can happen due to races, in addition to dates that are243 * truly in the past. To avoid requiring the caller to check for244 * races, dates in the past are assumed to be in the recent past245 * (i.e. not something that we'd rather the caller know about via246 * an error), and the alarm is set to go off as soon as possible.247 */248 if (time_before_eq(new_alarm, itime))249 new_alarm = 1;250 else251 new_alarm -= itime;252 253 mutex_lock(&ds1374->mutex);254 255 ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);256 if (ret < 0)257 goto out;258 259 /* Disable any existing alarm before setting the new one260 * (or lack thereof). */261 cr &= ~DS1374_REG_CR_WACE;262 263 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);264 if (ret < 0)265 goto out;266 267 ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);268 if (ret)269 goto out;270 271 if (alarm->enabled) {272 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;273 cr &= ~DS1374_REG_CR_WDALM;274 275 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);276 }277 278out:279 mutex_unlock(&ds1374->mutex);280 return ret;281}282#endif283 284static irqreturn_t ds1374_irq(int irq, void *dev_id)285{286 struct i2c_client *client = dev_id;287 struct ds1374 *ds1374 = i2c_get_clientdata(client);288 289 disable_irq_nosync(irq);290 schedule_work(&ds1374->work);291 return IRQ_HANDLED;292}293 294static void ds1374_work(struct work_struct *work)295{296 struct ds1374 *ds1374 = container_of(work, struct ds1374, work);297 struct i2c_client *client = ds1374->client;298 int stat, control;299 300 mutex_lock(&ds1374->mutex);301 302 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);303 if (stat < 0)304 goto unlock;305 306 if (stat & DS1374_REG_SR_AF) {307 stat &= ~DS1374_REG_SR_AF;308 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);309 310 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);311 if (control < 0)312 goto out;313 314 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);315 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);316 317 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);318 }319 320out:321 if (!ds1374->exiting)322 enable_irq(client->irq);323unlock:324 mutex_unlock(&ds1374->mutex);325}326 327#ifndef CONFIG_RTC_DRV_DS1374_WDT328static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)329{330 struct i2c_client *client = to_i2c_client(dev);331 struct ds1374 *ds1374 = i2c_get_clientdata(client);332 int ret;333 334 mutex_lock(&ds1374->mutex);335 336 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);337 if (ret < 0)338 goto out;339 340 if (enabled) {341 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;342 ret &= ~DS1374_REG_CR_WDALM;343 } else {344 ret &= ~DS1374_REG_CR_WACE;345 }346 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);347 348out:349 mutex_unlock(&ds1374->mutex);350 return ret;351}352#endif353 354static const struct rtc_class_ops ds1374_rtc_ops = {355 .read_time = ds1374_read_time,356 .set_time = ds1374_set_time,357#ifndef CONFIG_RTC_DRV_DS1374_WDT358 .read_alarm = ds1374_read_alarm,359 .set_alarm = ds1374_set_alarm,360 .alarm_irq_enable = ds1374_alarm_irq_enable,361#endif362};363 364#ifdef CONFIG_RTC_DRV_DS1374_WDT365/*366 *****************************************************************************367 *368 * Watchdog Driver369 *370 *****************************************************************************371 */372/* Default margin */373#define TIMER_MARGIN_DEFAULT 32374#define TIMER_MARGIN_MIN 1375#define TIMER_MARGIN_MAX 4095 /* 24-bit value */376 377static int wdt_margin;378module_param(wdt_margin, int, 0);379MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");380 381static bool nowayout = WATCHDOG_NOWAYOUT;382module_param(nowayout, bool, 0);383MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default ="384 __MODULE_STRING(WATCHDOG_NOWAYOUT)")");385 386static const struct watchdog_info ds1374_wdt_info = {387 .identity = "DS1374 Watchdog",388 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |389 WDIOF_MAGICCLOSE,390};391 392static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)393{394 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);395 struct i2c_client *client = ds1374->client;396 int ret, cr;397 398 wdt->timeout = timeout;399 400 cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);401 if (cr < 0)402 return cr;403 404 /* Disable any existing watchdog/alarm before setting the new one */405 cr &= ~DS1374_REG_CR_WACE;406 407 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);408 if (ret < 0)409 return ret;410 411 /* Set new watchdog time */412 timeout = timeout * 4096;413 ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3);414 if (ret)415 return ret;416 417 /* Enable watchdog timer */418 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;419 cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */420 cr &= ~DS1374_REG_CR_AIE;421 422 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);423 if (ret < 0)424 return ret;425 426 return 0;427}428 429/*430 * Reload the watchdog timer. (ie, pat the watchdog)431 */432static int ds1374_wdt_start(struct watchdog_device *wdt)433{434 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);435 u32 val;436 437 return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3);438}439 440static int ds1374_wdt_stop(struct watchdog_device *wdt)441{442 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);443 struct i2c_client *client = ds1374->client;444 int cr;445 446 cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);447 if (cr < 0)448 return cr;449 450 /* Disable watchdog timer */451 cr &= ~DS1374_REG_CR_WACE;452 453 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);454}455 456static const struct watchdog_ops ds1374_wdt_ops = {457 .owner = THIS_MODULE,458 .start = ds1374_wdt_start,459 .stop = ds1374_wdt_stop,460 .set_timeout = ds1374_wdt_settimeout,461};462#endif /*CONFIG_RTC_DRV_DS1374_WDT*/463/*464 *****************************************************************************465 *466 * Driver Interface467 *468 *****************************************************************************469 */470static int ds1374_probe(struct i2c_client *client)471{472 struct ds1374 *ds1374;473 int ret;474 475 ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);476 if (!ds1374)477 return -ENOMEM;478 479 ds1374->rtc = devm_rtc_allocate_device(&client->dev);480 if (IS_ERR(ds1374->rtc))481 return PTR_ERR(ds1374->rtc);482 483 ds1374->client = client;484 i2c_set_clientdata(client, ds1374);485 486 INIT_WORK(&ds1374->work, ds1374_work);487 mutex_init(&ds1374->mutex);488 489 ret = ds1374_check_rtc_status(client);490 if (ret)491 return ret;492 493 if (client->irq > 0) {494 ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,495 "ds1374", client);496 if (ret) {497 dev_err(&client->dev, "unable to request IRQ\n");498 return ret;499 }500 501 device_set_wakeup_capable(&client->dev, 1);502 }503 504 ds1374->rtc->ops = &ds1374_rtc_ops;505 ds1374->rtc->range_max = U32_MAX;506 507 ret = devm_rtc_register_device(ds1374->rtc);508 if (ret)509 return ret;510 511#ifdef CONFIG_RTC_DRV_DS1374_WDT512 ds1374->wdt.info = &ds1374_wdt_info;513 ds1374->wdt.ops = &ds1374_wdt_ops;514 ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;515 ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;516 ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;517 518 watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev);519 watchdog_set_nowayout(&ds1374->wdt, nowayout);520 watchdog_stop_on_reboot(&ds1374->wdt);521 watchdog_stop_on_unregister(&ds1374->wdt);522 watchdog_set_drvdata(&ds1374->wdt, ds1374);523 ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout);524 525 ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);526 if (ret)527 return ret;528#endif529 530 return 0;531}532 533static void ds1374_remove(struct i2c_client *client)534{535 struct ds1374 *ds1374 = i2c_get_clientdata(client);536 537 if (client->irq > 0) {538 mutex_lock(&ds1374->mutex);539 ds1374->exiting = 1;540 mutex_unlock(&ds1374->mutex);541 542 devm_free_irq(&client->dev, client->irq, client);543 cancel_work_sync(&ds1374->work);544 }545}546 547#ifdef CONFIG_PM_SLEEP548static int ds1374_suspend(struct device *dev)549{550 struct i2c_client *client = to_i2c_client(dev);551 552 if (client->irq > 0 && device_may_wakeup(&client->dev))553 enable_irq_wake(client->irq);554 return 0;555}556 557static int ds1374_resume(struct device *dev)558{559 struct i2c_client *client = to_i2c_client(dev);560 561 if (client->irq > 0 && device_may_wakeup(&client->dev))562 disable_irq_wake(client->irq);563 return 0;564}565#endif566 567static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);568 569static struct i2c_driver ds1374_driver = {570 .driver = {571 .name = "rtc-ds1374",572 .of_match_table = of_match_ptr(ds1374_of_match),573 .pm = &ds1374_pm,574 },575 .probe = ds1374_probe,576 .remove = ds1374_remove,577 .id_table = ds1374_id,578};579 580module_i2c_driver(ds1374_driver);581 582MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");583MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");584MODULE_LICENSE("GPL");585