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-rw-r--r--drivers/rtc/rtc-ds1374.c584
1 files changed, 584 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c
new file mode 100644
index 000000000..7f089f066
--- /dev/null
+++ b/drivers/rtc/rtc-ds1374.c
@@ -0,0 +1,584 @@
+// 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 <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
+ * 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 <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)
+{
+ 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 void 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);
+ }
+}
+
+#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_new = 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");