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![John Stultz](/assets/img/avatar_default.png)
Commit f44f7f96a2
("RTC: Initialize kernel state from RTC") uncovered
an issue in a number of RTC drivers, where the drivers call
rtc_device_register before initializing the device or platform drvdata.
This frequently results in null pointer dereferences when the
rtc_device_register immediately makes use of the rtc device, calling
rtc_read_alarm.
The solution is to ensure the drvdata is initialized prior to registering
the rtc device.
CC: Wolfram Sang <w.sang@pengutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: rtc-linux@googlegroups.com
Signed-off-by: John Stultz <john.stultz@linaro.org>
317 lines
7.9 KiB
C
317 lines
7.9 KiB
C
/*
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* RTC driver for Maxim MAX8925
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*
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* Copyright (C) 2009-2010 Marvell International Ltd.
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* Haojian Zhuang <haojian.zhuang@marvell.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/slab.h>
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#include <linux/rtc.h>
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#include <linux/platform_device.h>
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#include <linux/mfd/max8925.h>
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enum {
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RTC_SEC = 0,
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RTC_MIN,
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RTC_HOUR,
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RTC_WEEKDAY,
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RTC_DATE,
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RTC_MONTH,
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RTC_YEAR1,
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RTC_YEAR2,
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};
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#define MAX8925_RTC_SEC 0x00
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#define MAX8925_RTC_MIN 0x01
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#define MAX8925_RTC_HOUR 0x02
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#define MAX8925_RTC_WEEKDAY 0x03
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#define MAX8925_RTC_DATE 0x04
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#define MAX8925_RTC_MONTH 0x05
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#define MAX8925_RTC_YEAR1 0x06
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#define MAX8925_RTC_YEAR2 0x07
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#define MAX8925_ALARM0_SEC 0x08
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#define MAX8925_ALARM0_MIN 0x09
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#define MAX8925_ALARM0_HOUR 0x0a
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#define MAX8925_ALARM0_WEEKDAY 0x0b
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#define MAX8925_ALARM0_DATE 0x0c
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#define MAX8925_ALARM0_MON 0x0d
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#define MAX8925_ALARM0_YEAR1 0x0e
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#define MAX8925_ALARM0_YEAR2 0x0f
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#define MAX8925_ALARM1_SEC 0x10
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#define MAX8925_ALARM1_MIN 0x11
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#define MAX8925_ALARM1_HOUR 0x12
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#define MAX8925_ALARM1_WEEKDAY 0x13
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#define MAX8925_ALARM1_DATE 0x14
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#define MAX8925_ALARM1_MON 0x15
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#define MAX8925_ALARM1_YEAR1 0x16
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#define MAX8925_ALARM1_YEAR2 0x17
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#define MAX8925_RTC_CNTL 0x1b
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#define MAX8925_RTC_STATUS 0x20
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#define TIME_NUM 8
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#define ALARM_1SEC (1 << 7)
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#define HOUR_12 (1 << 7)
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#define HOUR_AM_PM (1 << 5)
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#define ALARM0_IRQ (1 << 3)
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#define ALARM1_IRQ (1 << 2)
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#define ALARM0_STATUS (1 << 2)
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#define ALARM1_STATUS (1 << 1)
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struct max8925_rtc_info {
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struct rtc_device *rtc_dev;
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struct max8925_chip *chip;
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struct i2c_client *rtc;
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struct device *dev;
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};
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static irqreturn_t rtc_update_handler(int irq, void *data)
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{
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struct max8925_rtc_info *info = (struct max8925_rtc_info *)data;
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/* disable ALARM0 except for 1SEC alarm */
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max8925_set_bits(info->rtc, MAX8925_ALARM0_CNTL, 0x7f, 0);
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rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);
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return IRQ_HANDLED;
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}
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static int tm_calc(struct rtc_time *tm, unsigned char *buf, int len)
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{
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if (len < TIME_NUM)
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return -EINVAL;
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tm->tm_year = (buf[RTC_YEAR2] >> 4) * 1000
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+ (buf[RTC_YEAR2] & 0xf) * 100
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+ (buf[RTC_YEAR1] >> 4) * 10
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+ (buf[RTC_YEAR1] & 0xf);
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tm->tm_year -= 1900;
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tm->tm_mon = ((buf[RTC_MONTH] >> 4) & 0x01) * 10
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+ (buf[RTC_MONTH] & 0x0f);
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tm->tm_mday = ((buf[RTC_DATE] >> 4) & 0x03) * 10
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+ (buf[RTC_DATE] & 0x0f);
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tm->tm_wday = buf[RTC_WEEKDAY] & 0x07;
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if (buf[RTC_HOUR] & HOUR_12) {
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tm->tm_hour = ((buf[RTC_HOUR] >> 4) & 0x1) * 10
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+ (buf[RTC_HOUR] & 0x0f);
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if (buf[RTC_HOUR] & HOUR_AM_PM)
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tm->tm_hour += 12;
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} else
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tm->tm_hour = ((buf[RTC_HOUR] >> 4) & 0x03) * 10
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+ (buf[RTC_HOUR] & 0x0f);
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tm->tm_min = ((buf[RTC_MIN] >> 4) & 0x7) * 10
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+ (buf[RTC_MIN] & 0x0f);
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tm->tm_sec = ((buf[RTC_SEC] >> 4) & 0x7) * 10
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+ (buf[RTC_SEC] & 0x0f);
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return 0;
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}
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static int data_calc(unsigned char *buf, struct rtc_time *tm, int len)
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{
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unsigned char high, low;
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if (len < TIME_NUM)
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return -EINVAL;
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high = (tm->tm_year + 1900) / 1000;
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low = (tm->tm_year + 1900) / 100;
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low = low - high * 10;
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buf[RTC_YEAR2] = (high << 4) + low;
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high = (tm->tm_year + 1900) / 10;
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low = tm->tm_year + 1900;
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low = low - high * 10;
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high = high - (high / 10) * 10;
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buf[RTC_YEAR1] = (high << 4) + low;
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high = tm->tm_mon / 10;
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low = tm->tm_mon;
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low = low - high * 10;
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buf[RTC_MONTH] = (high << 4) + low;
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high = tm->tm_mday / 10;
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low = tm->tm_mday;
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low = low - high * 10;
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buf[RTC_DATE] = (high << 4) + low;
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buf[RTC_WEEKDAY] = tm->tm_wday;
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high = tm->tm_hour / 10;
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low = tm->tm_hour;
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low = low - high * 10;
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buf[RTC_HOUR] = (high << 4) + low;
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high = tm->tm_min / 10;
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low = tm->tm_min;
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low = low - high * 10;
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buf[RTC_MIN] = (high << 4) + low;
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high = tm->tm_sec / 10;
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low = tm->tm_sec;
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low = low - high * 10;
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buf[RTC_SEC] = (high << 4) + low;
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return 0;
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}
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static int max8925_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct max8925_rtc_info *info = dev_get_drvdata(dev);
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unsigned char buf[TIME_NUM];
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int ret;
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ret = max8925_bulk_read(info->rtc, MAX8925_RTC_SEC, TIME_NUM, buf);
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if (ret < 0)
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goto out;
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ret = tm_calc(tm, buf, TIME_NUM);
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out:
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return ret;
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}
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static int max8925_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct max8925_rtc_info *info = dev_get_drvdata(dev);
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unsigned char buf[TIME_NUM];
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int ret;
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ret = data_calc(buf, tm, TIME_NUM);
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if (ret < 0)
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goto out;
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ret = max8925_bulk_write(info->rtc, MAX8925_RTC_SEC, TIME_NUM, buf);
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out:
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return ret;
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}
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static int max8925_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
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{
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struct max8925_rtc_info *info = dev_get_drvdata(dev);
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unsigned char buf[TIME_NUM];
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int ret;
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ret = max8925_bulk_read(info->rtc, MAX8925_ALARM0_SEC, TIME_NUM, buf);
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if (ret < 0)
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goto out;
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ret = tm_calc(&alrm->time, buf, TIME_NUM);
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if (ret < 0)
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goto out;
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ret = max8925_reg_read(info->rtc, MAX8925_RTC_IRQ_MASK);
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if (ret < 0)
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goto out;
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if ((ret & ALARM0_IRQ) == 0)
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alrm->enabled = 1;
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else
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alrm->enabled = 0;
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ret = max8925_reg_read(info->rtc, MAX8925_RTC_STATUS);
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if (ret < 0)
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goto out;
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if (ret & ALARM0_STATUS)
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alrm->pending = 1;
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else
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alrm->pending = 0;
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out:
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return ret;
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}
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static int max8925_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
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{
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struct max8925_rtc_info *info = dev_get_drvdata(dev);
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unsigned char buf[TIME_NUM];
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int ret;
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ret = data_calc(buf, &alrm->time, TIME_NUM);
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if (ret < 0)
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goto out;
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ret = max8925_bulk_write(info->rtc, MAX8925_ALARM0_SEC, TIME_NUM, buf);
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if (ret < 0)
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goto out;
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/* only enable alarm on year/month/day/hour/min/sec */
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ret = max8925_reg_write(info->rtc, MAX8925_ALARM0_CNTL, 0x77);
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if (ret < 0)
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goto out;
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out:
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return ret;
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}
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static const struct rtc_class_ops max8925_rtc_ops = {
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.read_time = max8925_rtc_read_time,
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.set_time = max8925_rtc_set_time,
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.read_alarm = max8925_rtc_read_alarm,
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.set_alarm = max8925_rtc_set_alarm,
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};
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static int __devinit max8925_rtc_probe(struct platform_device *pdev)
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{
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struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
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struct max8925_rtc_info *info;
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int irq, ret;
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info = kzalloc(sizeof(struct max8925_rtc_info), GFP_KERNEL);
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if (!info)
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return -ENOMEM;
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info->chip = chip;
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info->rtc = chip->rtc;
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info->dev = &pdev->dev;
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irq = chip->irq_base + MAX8925_IRQ_RTC_ALARM0;
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ret = request_threaded_irq(irq, NULL, rtc_update_handler,
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IRQF_ONESHOT, "rtc-alarm0", info);
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if (ret < 0) {
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dev_err(chip->dev, "Failed to request IRQ: #%d: %d\n",
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irq, ret);
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goto out_irq;
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}
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dev_set_drvdata(&pdev->dev, info);
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/* XXX - isn't this redundant? */
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platform_set_drvdata(pdev, info);
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info->rtc_dev = rtc_device_register("max8925-rtc", &pdev->dev,
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&max8925_rtc_ops, THIS_MODULE);
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ret = PTR_ERR(info->rtc_dev);
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if (IS_ERR(info->rtc_dev)) {
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dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
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goto out_rtc;
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}
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return 0;
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out_rtc:
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platform_set_drvdata(pdev, NULL);
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free_irq(chip->irq_base + MAX8925_IRQ_RTC_ALARM0, info);
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out_irq:
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kfree(info);
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return ret;
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}
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static int __devexit max8925_rtc_remove(struct platform_device *pdev)
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{
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struct max8925_rtc_info *info = platform_get_drvdata(pdev);
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if (info) {
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free_irq(info->chip->irq_base + MAX8925_IRQ_RTC_ALARM0, info);
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rtc_device_unregister(info->rtc_dev);
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kfree(info);
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}
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return 0;
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}
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static struct platform_driver max8925_rtc_driver = {
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.driver = {
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.name = "max8925-rtc",
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.owner = THIS_MODULE,
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},
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.probe = max8925_rtc_probe,
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.remove = __devexit_p(max8925_rtc_remove),
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};
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static int __init max8925_rtc_init(void)
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{
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return platform_driver_register(&max8925_rtc_driver);
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}
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module_init(max8925_rtc_init);
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static void __exit max8925_rtc_exit(void)
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{
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platform_driver_unregister(&max8925_rtc_driver);
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}
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module_exit(max8925_rtc_exit);
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MODULE_DESCRIPTION("Maxim MAX8925 RTC driver");
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MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
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MODULE_LICENSE("GPL");
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