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bf4994d781
This patch adds an RTC class driver for the Maxim/Dallas 1374 RTC chip, based on drivers/i2c/chips/ds1374.c. It supports alarm functionality. Signed-off-by: Scott Wood <scottwood@freescale.com> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
450 lines
10 KiB
C
450 lines
10 KiB
C
/*
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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) 2006-2007 Freescale Semiconductor
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*
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* 2005 (c) MontaVista Software, Inc. This file is licensed under
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* the terms of the GNU General Public License version 2. This program
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* is licensed "as is" without any warranty of any kind, whether express
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* or implied.
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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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* recommened in .../Documentation/i2c/writing-clients section
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* "Sending and receiving", using SMBus level communication is preferred.
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*/
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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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#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_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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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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/* 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 (nbytes > 4) {
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WARN_ON(1);
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return -EINVAL;
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}
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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, "
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"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_time_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;
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rtc_tm_to_time(time, &itime);
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return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
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}
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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_time_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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rtc_tm_to_time(&alarm->time, &new_alarm);
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rtc_tm_to_time(&now, &itime);
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new_alarm -= itime;
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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 (new_alarm <= 0)
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new_alarm = 1;
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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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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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return;
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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() assumes that it is called
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* from IRQ-disabled context.
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*/
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local_irq_disable();
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rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
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local_irq_enable();
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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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mutex_unlock(&ds1374->mutex);
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}
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static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
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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 = -ENOIOCTLCMD;
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mutex_lock(&ds1374->mutex);
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switch (cmd) {
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case RTC_AIE_OFF:
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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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ret &= ~DS1374_REG_CR_WACE;
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
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if (ret < 0)
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goto out;
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break;
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case RTC_AIE_ON:
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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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ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
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ret &= ~DS1374_REG_CR_WDALM;
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
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if (ret < 0)
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goto out;
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break;
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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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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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.read_alarm = ds1374_read_alarm,
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.set_alarm = ds1374_set_alarm,
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.ioctl = ds1374_ioctl,
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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 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
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if (!ds1374)
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return -ENOMEM;
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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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goto out_free;
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if (client->irq >= 0) {
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ret = request_irq(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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goto out_free;
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}
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}
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ds1374->rtc = rtc_device_register(client->name, &client->dev,
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&ds1374_rtc_ops, THIS_MODULE);
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if (IS_ERR(ds1374->rtc)) {
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ret = PTR_ERR(ds1374->rtc);
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dev_err(&client->dev, "unable to register the class device\n");
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goto out_irq;
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}
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return 0;
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out_irq:
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if (client->irq >= 0)
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free_irq(client->irq, client);
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out_free:
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i2c_set_clientdata(client, NULL);
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kfree(ds1374);
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return ret;
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}
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static int __devexit ds1374_remove(struct i2c_client *client)
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{
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struct ds1374 *ds1374 = i2c_get_clientdata(client);
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if (client->irq >= 0) {
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mutex_lock(&ds1374->mutex);
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ds1374->exiting = 1;
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mutex_unlock(&ds1374->mutex);
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free_irq(client->irq, client);
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flush_scheduled_work();
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}
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rtc_device_unregister(ds1374->rtc);
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i2c_set_clientdata(client, NULL);
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kfree(ds1374);
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return 0;
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}
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static struct i2c_driver ds1374_driver = {
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.driver = {
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.name = "rtc-ds1374",
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.owner = THIS_MODULE,
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},
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.probe = ds1374_probe,
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.remove = __devexit_p(ds1374_remove),
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};
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static int __init ds1374_init(void)
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{
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return i2c_add_driver(&ds1374_driver);
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}
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static void __exit ds1374_exit(void)
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{
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i2c_del_driver(&ds1374_driver);
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}
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module_init(ds1374_init);
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module_exit(ds1374_exit);
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MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
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MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
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MODULE_LICENSE("GPL");
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