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linux/drivers/rtc/rtc-max8925.c
John Stultz 2f5c4fe8f9 rtc: max8925: Initialize drvdata before registering device 
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>
2011-05-06 18:02:00 -07:00

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