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linux/drivers/rtc/rtc-max8998.c
John Stultz 03cf7c477d rtc: max8998: 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 18:02:02 -07:00

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/*
* RTC driver for Maxim MAX8998
*
* Copyright (C) 2010 Samsung Electronics Co.Ltd
* Author: Minkyu Kang <mk7.kang@samsung.com>
* Author: Joonyoung Shim <jy0922.shim@samsung.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
*/
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/mfd/max8998.h>
#include <linux/mfd/max8998-private.h>
#include <linux/delay.h>
#define MAX8998_RTC_SEC 0x00
#define MAX8998_RTC_MIN 0x01
#define MAX8998_RTC_HOUR 0x02
#define MAX8998_RTC_WEEKDAY 0x03
#define MAX8998_RTC_DATE 0x04
#define MAX8998_RTC_MONTH 0x05
#define MAX8998_RTC_YEAR1 0x06
#define MAX8998_RTC_YEAR2 0x07
#define MAX8998_ALARM0_SEC 0x08
#define MAX8998_ALARM0_MIN 0x09
#define MAX8998_ALARM0_HOUR 0x0a
#define MAX8998_ALARM0_WEEKDAY 0x0b
#define MAX8998_ALARM0_DATE 0x0c
#define MAX8998_ALARM0_MONTH 0x0d
#define MAX8998_ALARM0_YEAR1 0x0e
#define MAX8998_ALARM0_YEAR2 0x0f
#define MAX8998_ALARM1_SEC 0x10
#define MAX8998_ALARM1_MIN 0x11
#define MAX8998_ALARM1_HOUR 0x12
#define MAX8998_ALARM1_WEEKDAY 0x13
#define MAX8998_ALARM1_DATE 0x14
#define MAX8998_ALARM1_MONTH 0x15
#define MAX8998_ALARM1_YEAR1 0x16
#define MAX8998_ALARM1_YEAR2 0x17
#define MAX8998_ALARM0_CONF 0x18
#define MAX8998_ALARM1_CONF 0x19
#define MAX8998_RTC_STATUS 0x1a
#define MAX8998_WTSR_SMPL_CNTL 0x1b
#define MAX8998_TEST 0x1f
#define HOUR_12 (1 << 7)
#define HOUR_PM (1 << 5)
#define ALARM0_STATUS (1 << 1)
#define ALARM1_STATUS (1 << 2)
enum {
RTC_SEC = 0,
RTC_MIN,
RTC_HOUR,
RTC_WEEKDAY,
RTC_DATE,
RTC_MONTH,
RTC_YEAR1,
RTC_YEAR2,
};
struct max8998_rtc_info {
struct device *dev;
struct max8998_dev *max8998;
struct i2c_client *rtc;
struct rtc_device *rtc_dev;
int irq;
bool lp3974_bug_workaround;
};
static void max8998_data_to_tm(u8 *data, struct rtc_time *tm)
{
tm->tm_sec = bcd2bin(data[RTC_SEC]);
tm->tm_min = bcd2bin(data[RTC_MIN]);
if (data[RTC_HOUR] & HOUR_12) {
tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x1f);
if (data[RTC_HOUR] & HOUR_PM)
tm->tm_hour += 12;
} else
tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);
tm->tm_wday = data[RTC_WEEKDAY] & 0x07;
tm->tm_mday = bcd2bin(data[RTC_DATE]);
tm->tm_mon = bcd2bin(data[RTC_MONTH]);
tm->tm_year = bcd2bin(data[RTC_YEAR1]) + bcd2bin(data[RTC_YEAR2]) * 100;
tm->tm_year -= 1900;
}
static void max8998_tm_to_data(struct rtc_time *tm, u8 *data)
{
data[RTC_SEC] = bin2bcd(tm->tm_sec);
data[RTC_MIN] = bin2bcd(tm->tm_min);
data[RTC_HOUR] = bin2bcd(tm->tm_hour);
data[RTC_WEEKDAY] = tm->tm_wday;
data[RTC_DATE] = bin2bcd(tm->tm_mday);
data[RTC_MONTH] = bin2bcd(tm->tm_mon);
data[RTC_YEAR1] = bin2bcd(tm->tm_year % 100);
data[RTC_YEAR2] = bin2bcd((tm->tm_year + 1900) / 100);
}
static int max8998_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct max8998_rtc_info *info = dev_get_drvdata(dev);
u8 data[8];
int ret;
ret = max8998_bulk_read(info->rtc, MAX8998_RTC_SEC, 8, data);
if (ret < 0)
return ret;
max8998_data_to_tm(data, tm);
return rtc_valid_tm(tm);
}
static int max8998_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct max8998_rtc_info *info = dev_get_drvdata(dev);
u8 data[8];
int ret;
max8998_tm_to_data(tm, data);
ret = max8998_bulk_write(info->rtc, MAX8998_RTC_SEC, 8, data);
if (info->lp3974_bug_workaround)
msleep(2000);
return ret;
}
static int max8998_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct max8998_rtc_info *info = dev_get_drvdata(dev);
u8 data[8];
u8 val;
int ret;
ret = max8998_bulk_read(info->rtc, MAX8998_ALARM0_SEC, 8, data);
if (ret < 0)
return ret;
max8998_data_to_tm(data, &alrm->time);
ret = max8998_read_reg(info->rtc, MAX8998_ALARM0_CONF, &val);
if (ret < 0)
return ret;
alrm->enabled = !!val;
ret = max8998_read_reg(info->rtc, MAX8998_RTC_STATUS, &val);
if (ret < 0)
return ret;
if (val & ALARM0_STATUS)
alrm->pending = 1;
else
alrm->pending = 0;
return 0;
}
static int max8998_rtc_stop_alarm(struct max8998_rtc_info *info)
{
int ret = max8998_write_reg(info->rtc, MAX8998_ALARM0_CONF, 0);
if (info->lp3974_bug_workaround)
msleep(2000);
return ret;
}
static int max8998_rtc_start_alarm(struct max8998_rtc_info *info)
{
int ret;
u8 alarm0_conf = 0x77;
/* LP3974 with delay bug chips has rtc alarm bugs with "MONTH" field */
if (info->lp3974_bug_workaround)
alarm0_conf = 0x57;
ret = max8998_write_reg(info->rtc, MAX8998_ALARM0_CONF, alarm0_conf);
if (info->lp3974_bug_workaround)
msleep(2000);
return ret;
}
static int max8998_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct max8998_rtc_info *info = dev_get_drvdata(dev);
u8 data[8];
int ret;
max8998_tm_to_data(&alrm->time, data);
ret = max8998_rtc_stop_alarm(info);
if (ret < 0)
return ret;
ret = max8998_bulk_write(info->rtc, MAX8998_ALARM0_SEC, 8, data);
if (ret < 0)
return ret;
if (info->lp3974_bug_workaround)
msleep(2000);
if (alrm->enabled)
ret = max8998_rtc_start_alarm(info);
return ret;
}
static int max8998_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct max8998_rtc_info *info = dev_get_drvdata(dev);
if (enabled)
return max8998_rtc_start_alarm(info);
else
return max8998_rtc_stop_alarm(info);
}
static irqreturn_t max8998_rtc_alarm_irq(int irq, void *data)
{
struct max8998_rtc_info *info = data;
rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);
return IRQ_HANDLED;
}
static const struct rtc_class_ops max8998_rtc_ops = {
.read_time = max8998_rtc_read_time,
.set_time = max8998_rtc_set_time,
.read_alarm = max8998_rtc_read_alarm,
.set_alarm = max8998_rtc_set_alarm,
.alarm_irq_enable = max8998_rtc_alarm_irq_enable,
};
static int __devinit max8998_rtc_probe(struct platform_device *pdev)
{
struct max8998_dev *max8998 = dev_get_drvdata(pdev->dev.parent);
struct max8998_platform_data *pdata = dev_get_platdata(max8998->dev);
struct max8998_rtc_info *info;
int ret;
info = kzalloc(sizeof(struct max8998_rtc_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
info->dev = &pdev->dev;
info->max8998 = max8998;
info->rtc = max8998->rtc;
info->irq = max8998->irq_base + MAX8998_IRQ_ALARM0;
platform_set_drvdata(pdev, info);
info->rtc_dev = rtc_device_register("max8998-rtc", &pdev->dev,
&max8998_rtc_ops, THIS_MODULE);
if (IS_ERR(info->rtc_dev)) {
ret = PTR_ERR(info->rtc_dev);
dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
goto out_rtc;
}
ret = request_threaded_irq(info->irq, NULL, max8998_rtc_alarm_irq, 0,
"rtc-alarm0", info);
if (ret < 0)
dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
info->irq, ret);
dev_info(&pdev->dev, "RTC CHIP NAME: %s\n", pdev->id_entry->name);
if (pdata->rtc_delay) {
info->lp3974_bug_workaround = true;
dev_warn(&pdev->dev, "LP3974 with RTC REGERR option."
" RTC updates will be extremely slow.\n");
}
return 0;
out_rtc:
platform_set_drvdata(pdev, NULL);
kfree(info);
return ret;
}
static int __devexit max8998_rtc_remove(struct platform_device *pdev)
{
struct max8998_rtc_info *info = platform_get_drvdata(pdev);
if (info) {
free_irq(info->irq, info);
rtc_device_unregister(info->rtc_dev);
kfree(info);
}
return 0;
}
static const struct platform_device_id max8998_rtc_id[] = {
{ "max8998-rtc", TYPE_MAX8998 },
{ "lp3974-rtc", TYPE_LP3974 },
{ }
};
static struct platform_driver max8998_rtc_driver = {
.driver = {
.name = "max8998-rtc",
.owner = THIS_MODULE,
},
.probe = max8998_rtc_probe,
.remove = __devexit_p(max8998_rtc_remove),
.id_table = max8998_rtc_id,
};
static int __init max8998_rtc_init(void)
{
return platform_driver_register(&max8998_rtc_driver);
}
module_init(max8998_rtc_init);
static void __exit max8998_rtc_exit(void)
{
platform_driver_unregister(&max8998_rtc_driver);
}
module_exit(max8998_rtc_exit);
MODULE_AUTHOR("Minkyu Kang <mk7.kang@samsung.com>");
MODULE_AUTHOR("Joonyoung Shim <jy0922.shim@samsung.com>");
MODULE_DESCRIPTION("Maxim MAX8998 RTC driver");
MODULE_LICENSE("GPL");
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