// 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 <[email protected]>, * which was based on the m41t00.c by Mark Greer <[email protected]>. * * 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) … #include <linux/kernel.h> #include <linux/module.h> #include <linux/interrupt.h> #include <linux/i2c.h> #include <linux/rtc.h> #include <linux/bcd.h> #include <linux/workqueue.h> #include <linux/slab.h> #include <linux/pm.h> #ifdef CONFIG_RTC_DRV_DS1374_WDT #include <linux/fs.h> #include <linux/ioctl.h> #include <linux/miscdevice.h> #include <linux/reboot.h> #include <linux/watchdog.h> #endif #define DS1374_REG_TOD0 … #define DS1374_REG_TOD1 … #define DS1374_REG_TOD2 … #define DS1374_REG_TOD3 … #define DS1374_REG_WDALM0 … #define DS1374_REG_WDALM1 … #define DS1374_REG_WDALM2 … #define DS1374_REG_CR … #define DS1374_REG_CR_AIE … #define DS1374_REG_CR_WDSTR … #define DS1374_REG_CR_WDALM … #define DS1374_REG_CR_WACE … #define DS1374_REG_SR … #define DS1374_REG_SR_OSF … #define DS1374_REG_SR_AF … #define DS1374_REG_TCR … static const struct i2c_device_id ds1374_id[] = …; MODULE_DEVICE_TABLE(i2c, ds1374_id); #ifdef CONFIG_OF static const struct of_device_id ds1374_of_match[] = …; MODULE_DEVICE_TABLE(of, ds1374_of_match); #endif struct ds1374 { … }; static struct i2c_driver ds1374_driver; static int ds1374_read_rtc(struct i2c_client *client, u32 *time, int reg, int nbytes) { … } static int ds1374_write_rtc(struct i2c_client *client, u32 time, int reg, int nbytes) { … } static int ds1374_check_rtc_status(struct i2c_client *client) { … } static int ds1374_read_time(struct device *dev, struct rtc_time *time) { … } static int ds1374_set_time(struct device *dev, struct rtc_time *time) { … } #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) { … } static void ds1374_work(struct work_struct *work) { … } #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 = …; #ifdef CONFIG_RTC_DRV_DS1374_WDT /* ***************************************************************************** * * Watchdog Driver * ***************************************************************************** */ /* Default margin */ #define TIMER_MARGIN_DEFAULT … #define TIMER_MARGIN_MIN … #define TIMER_MARGIN_MAX … static int wdt_margin; module_param(wdt_margin, int, 0); MODULE_PARM_DESC(…) …; static bool nowayout = … WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(…) …; static const struct watchdog_info ds1374_wdt_info = …; static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout) { … } /* * Reload the watchdog timer. (ie, pat the watchdog) */ static int ds1374_wdt_start(struct watchdog_device *wdt) { … } static int ds1374_wdt_stop(struct watchdog_device *wdt) { … } static const struct watchdog_ops ds1374_wdt_ops = …; #endif /*CONFIG_RTC_DRV_DS1374_WDT*/ /* ***************************************************************************** * * Driver Interface * ***************************************************************************** */ static int ds1374_probe(struct i2c_client *client) { … } static void ds1374_remove(struct i2c_client *client) { … } #ifdef CONFIG_PM_SLEEP static int ds1374_suspend(struct device *dev) { … } static int ds1374_resume(struct device *dev) { … } #endif static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume); static struct i2c_driver ds1374_driver = …; module_i2c_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …;
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