rtc: add support for DS3232 RTC
Add a driver for the DS3232 RTC chip via the I2C bus. Alarms are not supported in this version of the driver. [akpm@linux-foundation.org: fix Kconfig help text] Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com> Signed-off-by: Jingchang Lu <b22599@freescale.com> Signed-off-by: Srikanth Srinivasan <srikanth.srinivasan@freescale.com> Signed-off-by: Roy Zang <tie-fei.zang@freescale.com> Acked-by: Wan ZongShun <mcuos.com@gmail.com> Cc: Kumar Gala <kumar.gala@freescale.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Roy Zang
Linus Torvalds
parent
2f11e57dad
commit
c03675f05f
3 changed files with 337 additions and 0 deletions
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@ -166,6 +166,16 @@ config RTC_DRV_DS1672
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This driver can also be built as a module. If so, the module
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will be called rtc-ds1672.
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config RTC_DRV_DS3232
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tristate "Dallas/Maxim DS3232"
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depends on RTC_CLASS && I2C
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help
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If you say yes here you get support for Dallas Semiconductor
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DS3232 real-time clock chips.
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This driver can also be built as a module. If so, the module
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will be called rtc-ds3232.
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config RTC_DRV_MAX6900
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tristate "Maxim MAX6900"
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help
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@ -41,6 +41,7 @@ obj-$(CONFIG_RTC_DRV_DS1511) += rtc-ds1511.o
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obj-$(CONFIG_RTC_DRV_DS1553) += rtc-ds1553.o
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obj-$(CONFIG_RTC_DRV_DS1672) += rtc-ds1672.o
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obj-$(CONFIG_RTC_DRV_DS1742) += rtc-ds1742.o
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obj-$(CONFIG_RTC_DRV_DS3232) += rtc-ds3232.o
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obj-$(CONFIG_RTC_DRV_DS3234) += rtc-ds3234.o
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obj-$(CONFIG_RTC_DRV_EFI) += rtc-efi.o
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obj-$(CONFIG_RTC_DRV_EP93XX) += rtc-ep93xx.o
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326
drivers/rtc/rtc-ds3232.c
Normal file
326
drivers/rtc/rtc-ds3232.c
Normal file
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@ -0,0 +1,326 @@
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/*
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* RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
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*
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* Copyright (C) 2009-2010 Freescale Semiconductor.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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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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#include <linux/slab.h>
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#define DS3232_REG_SECONDS 0x00
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#define DS3232_REG_MINUTES 0x01
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#define DS3232_REG_HOURS 0x02
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#define DS3232_REG_AMPM 0x02
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#define DS3232_REG_DAY 0x03
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#define DS3232_REG_DATE 0x04
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#define DS3232_REG_MONTH 0x05
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#define DS3232_REG_CENTURY 0x05
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#define DS3232_REG_YEAR 0x06
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#define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */
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#define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */
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#define DS3232_REG_CR 0x0E /* Control register */
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# define DS3232_REG_CR_nEOSC 0x80
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# define DS3232_REG_CR_INTCN 0x04
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# define DS3232_REG_CR_A2IE 0x02
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# define DS3232_REG_CR_A1IE 0x01
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#define DS3232_REG_SR 0x0F /* control/status register */
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# define DS3232_REG_SR_OSF 0x80
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# define DS3232_REG_SR_BSY 0x04
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# define DS3232_REG_SR_A2F 0x02
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# define DS3232_REG_SR_A1F 0x01
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struct ds3232 {
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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 ds3232_driver;
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static int ds3232_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, DS3232_REG_SR);
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if (stat < 0)
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return stat;
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if (stat & DS3232_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 &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
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ret = i2c_smbus_write_byte_data(client, DS3232_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, DS3232_REG_CR);
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if (control < 0)
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return control;
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control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
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control |= DS3232_REG_CR_INTCN;
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return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
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}
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static int ds3232_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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int ret;
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u8 buf[7];
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unsigned int year, month, day, hour, minute, second;
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unsigned int week, twelve_hr, am_pm;
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unsigned int century, add_century = 0;
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ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);
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if (ret < 0)
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return ret;
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if (ret < 7)
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return -EIO;
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second = buf[0];
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minute = buf[1];
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hour = buf[2];
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week = buf[3];
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day = buf[4];
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month = buf[5];
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year = buf[6];
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/* Extract additional information for AM/PM and century */
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twelve_hr = hour & 0x40;
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am_pm = hour & 0x20;
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century = month & 0x80;
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/* Write to rtc_time structure */
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time->tm_sec = bcd2bin(second);
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time->tm_min = bcd2bin(minute);
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if (twelve_hr) {
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/* Convert to 24 hr */
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if (am_pm)
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time->tm_hour = bcd2bin(hour & 0x1F) + 12;
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else
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time->tm_hour = bcd2bin(hour & 0x1F);
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} else {
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time->tm_hour = bcd2bin(hour);
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}
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time->tm_wday = bcd2bin(week);
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time->tm_mday = bcd2bin(day);
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time->tm_mon = bcd2bin(month & 0x7F);
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if (century)
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add_century = 100;
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time->tm_year = bcd2bin(year) + add_century;
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return rtc_valid_tm(time);
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}
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static int ds3232_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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u8 buf[7];
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/* Extract time from rtc_time and load into ds3232*/
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buf[0] = bin2bcd(time->tm_sec);
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buf[1] = bin2bcd(time->tm_min);
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buf[2] = bin2bcd(time->tm_hour);
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buf[3] = bin2bcd(time->tm_wday); /* Day of the week */
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buf[4] = bin2bcd(time->tm_mday); /* Date */
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buf[5] = bin2bcd(time->tm_mon);
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if (time->tm_year >= 100) {
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buf[5] |= 0x80;
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buf[6] = bin2bcd(time->tm_year - 100);
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} else {
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buf[6] = bin2bcd(time->tm_year);
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}
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return i2c_smbus_write_i2c_block_data(client,
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DS3232_REG_SECONDS, 7, buf);
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}
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static irqreturn_t ds3232_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 ds3232 *ds3232 = i2c_get_clientdata(client);
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disable_irq_nosync(irq);
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schedule_work(&ds3232->work);
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return IRQ_HANDLED;
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}
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static void ds3232_work(struct work_struct *work)
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{
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struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
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struct i2c_client *client = ds3232->client;
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int stat, control;
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mutex_lock(&ds3232->mutex);
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stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
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if (stat < 0)
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goto unlock;
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if (stat & DS3232_REG_SR_A1F) {
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control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
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if (control < 0)
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goto out;
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/* disable alarm1 interrupt */
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control &= ~(DS3232_REG_CR_A1IE);
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i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
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/* clear the alarm pend flag */
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stat &= ~DS3232_REG_SR_A1F;
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i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
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rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
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}
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out:
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if (!ds3232->exiting)
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enable_irq(client->irq);
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unlock:
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mutex_unlock(&ds3232->mutex);
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}
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static const struct rtc_class_ops ds3232_rtc_ops = {
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.read_time = ds3232_read_time,
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.set_time = ds3232_set_time,
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};
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static int __devinit ds3232_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct ds3232 *ds3232;
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int ret;
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ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL);
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if (!ds3232)
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return -ENOMEM;
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ds3232->client = client;
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i2c_set_clientdata(client, ds3232);
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INIT_WORK(&ds3232->work, ds3232_work);
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mutex_init(&ds3232->mutex);
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ret = ds3232_check_rtc_status(client);
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if (ret)
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goto out_free;
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ds3232->rtc = rtc_device_register(client->name, &client->dev,
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&ds3232_rtc_ops, THIS_MODULE);
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if (IS_ERR(ds3232->rtc)) {
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ret = PTR_ERR(ds3232->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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if (client->irq >= 0) {
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ret = request_irq(client->irq, ds3232_irq, 0,
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"ds3232", 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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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(ds3232);
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return ret;
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}
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static int __devexit ds3232_remove(struct i2c_client *client)
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{
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struct ds3232 *ds3232 = i2c_get_clientdata(client);
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if (client->irq >= 0) {
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mutex_lock(&ds3232->mutex);
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ds3232->exiting = 1;
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mutex_unlock(&ds3232->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(ds3232->rtc);
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i2c_set_clientdata(client, NULL);
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kfree(ds3232);
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return 0;
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}
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static const struct i2c_device_id ds3232_id[] = {
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{ "ds3232", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ds3232_id);
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static struct i2c_driver ds3232_driver = {
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.driver = {
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.name = "rtc-ds3232",
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.owner = THIS_MODULE,
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},
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.probe = ds3232_probe,
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.remove = __devexit_p(ds3232_remove),
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.id_table = ds3232_id,
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};
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static int __init ds3232_init(void)
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{
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return i2c_add_driver(&ds3232_driver);
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}
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static void __exit ds3232_exit(void)
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{
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i2c_del_driver(&ds3232_driver);
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}
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module_init(ds3232_init);
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module_exit(ds3232_exit);
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MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
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MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
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MODULE_LICENSE("GPL");
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