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