// SPDX-License-Identifier: GPL-2.0-only /* * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C * * Based on code by Randy Vinson , * which was based on the m41t00.c by Mark Greer . * * Copyright (C) 2014 Rose Technology * Copyright (C) 2006-2007 Freescale Semiconductor * Copyright (c) 2005 MontaVista Software, Inc. */ /* * It would be more efficient to use i2c msgs/i2c_transfer directly but, as * recommended in .../Documentation/i2c/writing-clients.rst section * "Sending and receiving", using SMBus level communication is preferred. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #ifdef CONFIG_RTC_DRV_DS1374_WDT #include #include #include #include #include #endif #define DS1374_REG_TOD0 0x00 /* Time of Day */ #define DS1374_REG_TOD1 0x01 #define DS1374_REG_TOD2 0x02 #define DS1374_REG_TOD3 0x03 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */ #define DS1374_REG_WDALM1 0x05 #define DS1374_REG_WDALM2 0x06 #define DS1374_REG_CR 0x07 /* Control */ #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */ #define DS1374_REG_CR_WDSTR 0x08 /* 1=INT, 0=RST */ #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */ #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */ #define DS1374_REG_SR 0x08 /* Status */ #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */ #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */ #define DS1374_REG_TCR 0x09 /* Trickle Charge */ static const struct i2c_device_id ds1374_id[] = { { "ds1374", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, ds1374_id); #ifdef CONFIG_OF static const struct of_device_id ds1374_of_match[] = { { .compatible = "dallas,ds1374" }, { } }; MODULE_DEVICE_TABLE(of, ds1374_of_match); #endif struct ds1374 { struct i2c_client *client; struct rtc_device *rtc; struct work_struct work; #ifdef CONFIG_RTC_DRV_DS1374_WDT struct watchdog_device wdt; #endif /* The mutex protects alarm operations, and prevents a race * between the enable_irq() in the workqueue and the free_irq() * in the remove function. */ struct mutex mutex; int exiting; }; static struct i2c_driver ds1374_driver; static int ds1374_read_rtc(struct i2c_client *client, u32 *time, int reg, int nbytes) { u8 buf[4]; int ret; int i; if (WARN_ON(nbytes > 4)) return -EINVAL; ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf); if (ret < 0) return ret; if (ret < nbytes) return -EIO; for (i = nbytes - 1, *time = 0; i >= 0; i--) *time = (*time << 8) | buf[i]; return 0; } static int ds1374_write_rtc(struct i2c_client *client, u32 time, int reg, int nbytes) { u8 buf[4]; int i; if (nbytes > 4) { WARN_ON(1); return -EINVAL; } for (i = 0; i < nbytes; i++) { buf[i] = time & 0xff; time >>= 8; } return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf); } static int ds1374_check_rtc_status(struct i2c_client *client) { int ret = 0; int control, stat; stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); if (stat < 0) return stat; if (stat & DS1374_REG_SR_OSF) dev_warn(&client->dev, "oscillator discontinuity flagged, time unreliable\n"); stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF); ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); if (ret < 0) return ret; /* If the alarm is pending, clear it before requesting * the interrupt, so an interrupt event isn't reported * before everything is initialized. */ control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (control < 0) return control; control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); } static int ds1374_read_time(struct device *dev, struct rtc_time *time) { struct i2c_client *client = to_i2c_client(dev); u32 itime; int ret; ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4); if (!ret) rtc_time64_to_tm(itime, time); return ret; } static int ds1374_set_time(struct device *dev, struct rtc_time *time) { struct i2c_client *client = to_i2c_client(dev); unsigned long itime = rtc_tm_to_time64(time); return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4); } #ifndef CONFIG_RTC_DRV_DS1374_WDT /* The ds1374 has a decrementer for an alarm, rather than a comparator. * If the time of day is changed, then the alarm will need to be * reset. */ static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) { struct i2c_client *client = to_i2c_client(dev); struct ds1374 *ds1374 = i2c_get_clientdata(client); u32 now, cur_alarm; int cr, sr; int ret = 0; if (client->irq <= 0) return -EINVAL; mutex_lock(&ds1374->mutex); cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR); if (ret < 0) goto out; ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4); if (ret) goto out; ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3); if (ret) goto out; rtc_time64_to_tm(now + cur_alarm, &alarm->time); alarm->enabled = !!(cr & DS1374_REG_CR_WACE); alarm->pending = !!(sr & DS1374_REG_SR_AF); out: mutex_unlock(&ds1374->mutex); return ret; } static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) { struct i2c_client *client = to_i2c_client(dev); struct ds1374 *ds1374 = i2c_get_clientdata(client); struct rtc_time now; unsigned long new_alarm, itime; int cr; int ret = 0; if (client->irq <= 0) return -EINVAL; ret = ds1374_read_time(dev, &now); if (ret < 0) return ret; new_alarm = rtc_tm_to_time64(&alarm->time); itime = rtc_tm_to_time64(&now); /* This can happen due to races, in addition to dates that are * truly in the past. To avoid requiring the caller to check for * races, dates in the past are assumed to be in the recent past * (i.e. not something that we'd rather the caller know about via * an error), and the alarm is set to go off as soon as possible. */ if (time_before_eq(new_alarm, itime)) new_alarm = 1; else new_alarm -= itime; mutex_lock(&ds1374->mutex); ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; /* Disable any existing alarm before setting the new one * (or lack thereof). */ cr &= ~DS1374_REG_CR_WACE; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); if (ret < 0) goto out; ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3); if (ret) goto out; if (alarm->enabled) { cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; cr &= ~DS1374_REG_CR_WDALM; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); } out: mutex_unlock(&ds1374->mutex); return ret; } #endif static irqreturn_t ds1374_irq(int irq, void *dev_id) { struct i2c_client *client = dev_id; struct ds1374 *ds1374 = i2c_get_clientdata(client); disable_irq_nosync(irq); schedule_work(&ds1374->work); return IRQ_HANDLED; } static void ds1374_work(struct work_struct *work) { struct ds1374 *ds1374 = container_of(work, struct ds1374, work); struct i2c_client *client = ds1374->client; int stat, control; mutex_lock(&ds1374->mutex); stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); if (stat < 0) goto unlock; if (stat & DS1374_REG_SR_AF) { stat &= ~DS1374_REG_SR_AF; i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (control < 0) goto out; control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); } out: if (!ds1374->exiting) enable_irq(client->irq); unlock: mutex_unlock(&ds1374->mutex); } #ifndef CONFIG_RTC_DRV_DS1374_WDT static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled) { struct i2c_client *client = to_i2c_client(dev); struct ds1374 *ds1374 = i2c_get_clientdata(client); int ret; mutex_lock(&ds1374->mutex); ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; if (enabled) { ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; ret &= ~DS1374_REG_CR_WDALM; } else { ret &= ~DS1374_REG_CR_WACE; } ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); out: mutex_unlock(&ds1374->mutex); return ret; } #endif static const struct rtc_class_ops ds1374_rtc_ops = { .read_time = ds1374_read_time, .set_time = ds1374_set_time, #ifndef CONFIG_RTC_DRV_DS1374_WDT .read_alarm = ds1374_read_alarm, .set_alarm = ds1374_set_alarm, .alarm_irq_enable = ds1374_alarm_irq_enable, #endif }; #ifdef CONFIG_RTC_DRV_DS1374_WDT /* ***************************************************************************** * * Watchdog Driver * ***************************************************************************** */ /* Default margin */ #define TIMER_MARGIN_DEFAULT 32 #define TIMER_MARGIN_MIN 1 #define TIMER_MARGIN_MAX 4095 /* 24-bit value */ static int wdt_margin; module_param(wdt_margin, int, 0); MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)"); static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default =" __MODULE_STRING(WATCHDOG_NOWAYOUT)")"); static const struct watchdog_info ds1374_wdt_info = { .identity = "DS1374 Watchdog", .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, }; static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout) { struct ds1374 *ds1374 = watchdog_get_drvdata(wdt); struct i2c_client *client = ds1374->client; int ret, cr; wdt->timeout = timeout; cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (cr < 0) return cr; /* Disable any existing watchdog/alarm before setting the new one */ cr &= ~DS1374_REG_CR_WACE; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); if (ret < 0) return ret; /* Set new watchdog time */ timeout = timeout * 4096; ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3); if (ret) return ret; /* Enable watchdog timer */ cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM; cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */ cr &= ~DS1374_REG_CR_AIE; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); if (ret < 0) return ret; return 0; } /* * Reload the watchdog timer. (ie, pat the watchdog) */ static int ds1374_wdt_start(struct watchdog_device *wdt) { struct ds1374 *ds1374 = watchdog_get_drvdata(wdt); u32 val; return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3); } static int ds1374_wdt_stop(struct watchdog_device *wdt) { struct ds1374 *ds1374 = watchdog_get_drvdata(wdt); struct i2c_client *client = ds1374->client; int cr; cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (cr < 0) return cr; /* Disable watchdog timer */ cr &= ~DS1374_REG_CR_WACE; return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); } static const struct watchdog_ops ds1374_wdt_ops = { .owner = THIS_MODULE, .start = ds1374_wdt_start, .stop = ds1374_wdt_stop, .set_timeout = ds1374_wdt_settimeout, }; #endif /*CONFIG_RTC_DRV_DS1374_WDT*/ /* ***************************************************************************** * * Driver Interface * ***************************************************************************** */ static int ds1374_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct ds1374 *ds1374; int ret; ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL); if (!ds1374) return -ENOMEM; ds1374->rtc = devm_rtc_allocate_device(&client->dev); if (IS_ERR(ds1374->rtc)) return PTR_ERR(ds1374->rtc); ds1374->client = client; i2c_set_clientdata(client, ds1374); INIT_WORK(&ds1374->work, ds1374_work); mutex_init(&ds1374->mutex); ret = ds1374_check_rtc_status(client); if (ret) return ret; if (client->irq > 0) { ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0, "ds1374", client); if (ret) { dev_err(&client->dev, "unable to request IRQ\n"); return ret; } device_set_wakeup_capable(&client->dev, 1); } ds1374->rtc->ops = &ds1374_rtc_ops; ds1374->rtc->range_max = U32_MAX; ret = devm_rtc_register_device(ds1374->rtc); if (ret) return ret; #ifdef CONFIG_RTC_DRV_DS1374_WDT ds1374->wdt.info = &ds1374_wdt_info; ds1374->wdt.ops = &ds1374_wdt_ops; ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT; ds1374->wdt.min_timeout = TIMER_MARGIN_MIN; ds1374->wdt.max_timeout = TIMER_MARGIN_MAX; watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev); watchdog_set_nowayout(&ds1374->wdt, nowayout); watchdog_stop_on_reboot(&ds1374->wdt); watchdog_stop_on_unregister(&ds1374->wdt); watchdog_set_drvdata(&ds1374->wdt, ds1374); ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout); ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt); if (ret) return ret; #endif return 0; } static int ds1374_remove(struct i2c_client *client) { struct ds1374 *ds1374 = i2c_get_clientdata(client); if (client->irq > 0) { mutex_lock(&ds1374->mutex); ds1374->exiting = 1; mutex_unlock(&ds1374->mutex); devm_free_irq(&client->dev, client->irq, client); cancel_work_sync(&ds1374->work); } return 0; } #ifdef CONFIG_PM_SLEEP static int ds1374_suspend(struct device *dev) { struct i2c_client *client = to_i2c_client(dev); if (client->irq > 0 && device_may_wakeup(&client->dev)) enable_irq_wake(client->irq); return 0; } static int ds1374_resume(struct device *dev) { struct i2c_client *client = to_i2c_client(dev); if (client->irq > 0 && device_may_wakeup(&client->dev)) disable_irq_wake(client->irq); return 0; } #endif static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume); static struct i2c_driver ds1374_driver = { .driver = { .name = "rtc-ds1374", .of_match_table = of_match_ptr(ds1374_of_match), .pm = &ds1374_pm, }, .probe = ds1374_probe, .remove = ds1374_remove, .id_table = ds1374_id, }; module_i2c_driver(ds1374_driver); MODULE_AUTHOR("Scott Wood "); MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); MODULE_LICENSE("GPL");