diff options
Diffstat (limited to 'drivers/rtc/rtc-ds1374.c')
| -rw-r--r-- | drivers/rtc/rtc-ds1374.c | 590 |
1 files changed, 590 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c new file mode 100644 index 000000000..177d870bd --- /dev/null +++ b/drivers/rtc/rtc-ds1374.c @@ -0,0 +1,590 @@ +/* + * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C + * + * Based on code by Randy Vinson <rvinson@mvista.com>, + * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>. + * + * Copyright (C) 2014 Rose Technology + * Copyright (C) 2006-2007 Freescale Semiconductor + * + * 2005 (c) MontaVista Software, Inc. This file is licensed under + * the terms of the GNU General Public License version 2. This program + * is licensed "as is" without any warranty of any kind, whether express + * or implied. + */ +/* + * 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 <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 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 = 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 <scottwood@freescale.com>"); +MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); +MODULE_LICENSE("GPL"); |