kernel-ark/drivers/rtc/rtc-dev.c
David Brownell f8245c2688 rtc: remove "RTC_ALM_SET mode" bugs
This fixes a common glitch in how RTC drivers handle two "set alarm" modes,
by getting rid of the surprising/hidden one that was rarely implemented
correctly (and which could expose nonportable hardware-specific behavior).

The glitch comes from the /dev/rtcX logic implementing the legacy
RTC_ALM_SET (limited to 24 hours, needing RTC_AIE_ON) ioctl on top of the
RTC driver call providing access to the newer RTC_WKALM_SET (without those
limitations) by initializing the day/month/year fields to be invalid ...
that second mode.

Now, since few RTC drivers check those fields, and most hardware misbehaves
when faced with invalid date fields, many RTC drivers will set bogus alarm
times on those RTC_ALM_SET code paths.  (Several in-tree drivers have that
issue, and I also noticed it with code reviews on several new RTC drivers.)

This patch ensures that RTC drivers never see such invalid alarm fields, by
moving some logic out of rtc-omap into the RTC_ALM_SET code and adding an
explicit check (which will prevent the issue on other code paths).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Scott Wood <scottwood@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>
2007-05-08 11:15:19 -07:00

490 lines
11 KiB
C

/*
* RTC subsystem, dev interface
*
* Copyright (C) 2005 Tower Technologies
* Author: Alessandro Zummo <a.zummo@towertech.it>
*
* based on arch/arm/common/rtctime.c
*
* 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/rtc.h>
#include "rtc-core.h"
static dev_t rtc_devt;
#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
static int rtc_dev_open(struct inode *inode, struct file *file)
{
int err;
struct rtc_device *rtc = container_of(inode->i_cdev,
struct rtc_device, char_dev);
const struct rtc_class_ops *ops = rtc->ops;
/* We keep the lock as long as the device is in use
* and return immediately if busy
*/
if (!(mutex_trylock(&rtc->char_lock)))
return -EBUSY;
file->private_data = rtc;
err = ops->open ? ops->open(rtc->dev.parent) : 0;
if (err == 0) {
spin_lock_irq(&rtc->irq_lock);
rtc->irq_data = 0;
spin_unlock_irq(&rtc->irq_lock);
return 0;
}
/* something has gone wrong, release the lock */
mutex_unlock(&rtc->char_lock);
return err;
}
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
/*
* Routine to poll RTC seconds field for change as often as possible,
* after first RTC_UIE use timer to reduce polling
*/
static void rtc_uie_task(struct work_struct *work)
{
struct rtc_device *rtc =
container_of(work, struct rtc_device, uie_task);
struct rtc_time tm;
int num = 0;
int err;
err = rtc_read_time(rtc, &tm);
local_irq_disable();
spin_lock(&rtc->irq_lock);
if (rtc->stop_uie_polling || err) {
rtc->uie_task_active = 0;
} else if (rtc->oldsecs != tm.tm_sec) {
num = (tm.tm_sec + 60 - rtc->oldsecs) % 60;
rtc->oldsecs = tm.tm_sec;
rtc->uie_timer.expires = jiffies + HZ - (HZ/10);
rtc->uie_timer_active = 1;
rtc->uie_task_active = 0;
add_timer(&rtc->uie_timer);
} else if (schedule_work(&rtc->uie_task) == 0) {
rtc->uie_task_active = 0;
}
spin_unlock(&rtc->irq_lock);
if (num)
rtc_update_irq(rtc, num, RTC_UF | RTC_IRQF);
local_irq_enable();
}
static void rtc_uie_timer(unsigned long data)
{
struct rtc_device *rtc = (struct rtc_device *)data;
unsigned long flags;
spin_lock_irqsave(&rtc->irq_lock, flags);
rtc->uie_timer_active = 0;
rtc->uie_task_active = 1;
if ((schedule_work(&rtc->uie_task) == 0))
rtc->uie_task_active = 0;
spin_unlock_irqrestore(&rtc->irq_lock, flags);
}
static void clear_uie(struct rtc_device *rtc)
{
spin_lock_irq(&rtc->irq_lock);
if (rtc->irq_active) {
rtc->stop_uie_polling = 1;
if (rtc->uie_timer_active) {
spin_unlock_irq(&rtc->irq_lock);
del_timer_sync(&rtc->uie_timer);
spin_lock_irq(&rtc->irq_lock);
rtc->uie_timer_active = 0;
}
if (rtc->uie_task_active) {
spin_unlock_irq(&rtc->irq_lock);
flush_scheduled_work();
spin_lock_irq(&rtc->irq_lock);
}
rtc->irq_active = 0;
}
spin_unlock_irq(&rtc->irq_lock);
}
static int set_uie(struct rtc_device *rtc)
{
struct rtc_time tm;
int err;
err = rtc_read_time(rtc, &tm);
if (err)
return err;
spin_lock_irq(&rtc->irq_lock);
if (!rtc->irq_active) {
rtc->irq_active = 1;
rtc->stop_uie_polling = 0;
rtc->oldsecs = tm.tm_sec;
rtc->uie_task_active = 1;
if (schedule_work(&rtc->uie_task) == 0)
rtc->uie_task_active = 0;
}
rtc->irq_data = 0;
spin_unlock_irq(&rtc->irq_lock);
return 0;
}
#endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */
static ssize_t
rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct rtc_device *rtc = to_rtc_device(file->private_data);
DECLARE_WAITQUEUE(wait, current);
unsigned long data;
ssize_t ret;
if (count != sizeof(unsigned int) && count < sizeof(unsigned long))
return -EINVAL;
add_wait_queue(&rtc->irq_queue, &wait);
do {
__set_current_state(TASK_INTERRUPTIBLE);
spin_lock_irq(&rtc->irq_lock);
data = rtc->irq_data;
rtc->irq_data = 0;
spin_unlock_irq(&rtc->irq_lock);
if (data != 0) {
ret = 0;
break;
}
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
schedule();
} while (1);
set_current_state(TASK_RUNNING);
remove_wait_queue(&rtc->irq_queue, &wait);
if (ret == 0) {
/* Check for any data updates */
if (rtc->ops->read_callback)
data = rtc->ops->read_callback(rtc->dev.parent,
data);
if (sizeof(int) != sizeof(long) &&
count == sizeof(unsigned int))
ret = put_user(data, (unsigned int __user *)buf) ?:
sizeof(unsigned int);
else
ret = put_user(data, (unsigned long __user *)buf) ?:
sizeof(unsigned long);
}
return ret;
}
static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
{
struct rtc_device *rtc = to_rtc_device(file->private_data);
unsigned long data;
poll_wait(file, &rtc->irq_queue, wait);
data = rtc->irq_data;
return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
}
static int rtc_dev_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
int err = 0;
struct rtc_device *rtc = file->private_data;
const struct rtc_class_ops *ops = rtc->ops;
struct rtc_time tm;
struct rtc_wkalrm alarm;
void __user *uarg = (void __user *) arg;
/* check that the calling task has appropriate permissions
* for certain ioctls. doing this check here is useful
* to avoid duplicate code in each driver.
*/
switch (cmd) {
case RTC_EPOCH_SET:
case RTC_SET_TIME:
if (!capable(CAP_SYS_TIME))
return -EACCES;
break;
case RTC_IRQP_SET:
if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
return -EACCES;
break;
case RTC_PIE_ON:
if (!capable(CAP_SYS_RESOURCE))
return -EACCES;
break;
}
/* avoid conflicting IRQ users */
if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
spin_lock_irq(&rtc->irq_task_lock);
if (rtc->irq_task)
err = -EBUSY;
spin_unlock_irq(&rtc->irq_task_lock);
if (err < 0)
return err;
}
/* try the driver's ioctl interface */
if (ops->ioctl) {
err = ops->ioctl(rtc->dev.parent, cmd, arg);
if (err != -ENOIOCTLCMD)
return err;
}
/* if the driver does not provide the ioctl interface
* or if that particular ioctl was not implemented
* (-ENOIOCTLCMD), we will try to emulate here.
*/
switch (cmd) {
case RTC_ALM_READ:
err = rtc_read_alarm(rtc, &alarm);
if (err < 0)
return err;
if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
return -EFAULT;
break;
case RTC_ALM_SET:
if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
return -EFAULT;
alarm.enabled = 0;
alarm.pending = 0;
alarm.time.tm_wday = -1;
alarm.time.tm_yday = -1;
alarm.time.tm_isdst = -1;
/* RTC_ALM_SET alarms may be up to 24 hours in the future.
* Rather than expecting every RTC to implement "don't care"
* for day/month/year fields, just force the alarm to have
* the right values for those fields.
*
* RTC_WKALM_SET should be used instead. Not only does it
* eliminate the need for a separate RTC_AIE_ON call, it
* doesn't have the "alarm 23:59:59 in the future" race.
*
* NOTE: some legacy code may have used invalid fields as
* wildcards, exposing hardware "periodic alarm" capabilities.
* Not supported here.
*/
{
unsigned long now, then;
err = rtc_read_time(rtc, &tm);
if (err < 0)
return err;
rtc_tm_to_time(&tm, &now);
alarm.time.tm_mday = tm.tm_mday;
alarm.time.tm_mon = tm.tm_mon;
alarm.time.tm_year = tm.tm_year;
err = rtc_valid_tm(&alarm.time);
if (err < 0)
return err;
rtc_tm_to_time(&alarm.time, &then);
/* alarm may need to wrap into tomorrow */
if (then < now) {
rtc_time_to_tm(now + 24 * 60 * 60, &tm);
alarm.time.tm_mday = tm.tm_mday;
alarm.time.tm_mon = tm.tm_mon;
alarm.time.tm_year = tm.tm_year;
}
}
err = rtc_set_alarm(rtc, &alarm);
break;
case RTC_RD_TIME:
err = rtc_read_time(rtc, &tm);
if (err < 0)
return err;
if (copy_to_user(uarg, &tm, sizeof(tm)))
return -EFAULT;
break;
case RTC_SET_TIME:
if (copy_from_user(&tm, uarg, sizeof(tm)))
return -EFAULT;
err = rtc_set_time(rtc, &tm);
break;
case RTC_IRQP_READ:
if (ops->irq_set_freq)
err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
break;
case RTC_IRQP_SET:
if (ops->irq_set_freq)
err = rtc_irq_set_freq(rtc, rtc->irq_task, arg);
break;
#if 0
case RTC_EPOCH_SET:
#ifndef rtc_epoch
/*
* There were no RTC clocks before 1900.
*/
if (arg < 1900) {
err = -EINVAL;
break;
}
rtc_epoch = arg;
err = 0;
#endif
break;
case RTC_EPOCH_READ:
err = put_user(rtc_epoch, (unsigned long __user *)uarg);
break;
#endif
case RTC_WKALM_SET:
if (copy_from_user(&alarm, uarg, sizeof(alarm)))
return -EFAULT;
err = rtc_set_alarm(rtc, &alarm);
break;
case RTC_WKALM_RD:
err = rtc_read_alarm(rtc, &alarm);
if (err < 0)
return err;
if (copy_to_user(uarg, &alarm, sizeof(alarm)))
return -EFAULT;
break;
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
case RTC_UIE_OFF:
clear_uie(rtc);
return 0;
case RTC_UIE_ON:
return set_uie(rtc);
#endif
default:
err = -ENOTTY;
break;
}
return err;
}
static int rtc_dev_release(struct inode *inode, struct file *file)
{
struct rtc_device *rtc = to_rtc_device(file->private_data);
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
clear_uie(rtc);
#endif
if (rtc->ops->release)
rtc->ops->release(rtc->dev.parent);
mutex_unlock(&rtc->char_lock);
return 0;
}
static int rtc_dev_fasync(int fd, struct file *file, int on)
{
struct rtc_device *rtc = to_rtc_device(file->private_data);
return fasync_helper(fd, file, on, &rtc->async_queue);
}
static const struct file_operations rtc_dev_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = rtc_dev_read,
.poll = rtc_dev_poll,
.ioctl = rtc_dev_ioctl,
.open = rtc_dev_open,
.release = rtc_dev_release,
.fasync = rtc_dev_fasync,
};
/* insertion/removal hooks */
void rtc_dev_prepare(struct rtc_device *rtc)
{
if (!rtc_devt)
return;
if (rtc->id >= RTC_DEV_MAX) {
pr_debug("%s: too many RTC devices\n", rtc->name);
return;
}
rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
mutex_init(&rtc->char_lock);
spin_lock_init(&rtc->irq_lock);
init_waitqueue_head(&rtc->irq_queue);
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
INIT_WORK(&rtc->uie_task, rtc_uie_task);
setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
#endif
cdev_init(&rtc->char_dev, &rtc_dev_fops);
rtc->char_dev.owner = rtc->owner;
}
void rtc_dev_add_device(struct rtc_device *rtc)
{
if (cdev_add(&rtc->char_dev, rtc->dev.devt, 1))
printk(KERN_WARNING "%s: failed to add char device %d:%d\n",
rtc->name, MAJOR(rtc_devt), rtc->id);
else
pr_debug("%s: dev (%d:%d)\n", rtc->name,
MAJOR(rtc_devt), rtc->id);
}
void rtc_dev_del_device(struct rtc_device *rtc)
{
if (rtc->dev.devt)
cdev_del(&rtc->char_dev);
}
void __init rtc_dev_init(void)
{
int err;
err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
if (err < 0)
printk(KERN_ERR "%s: failed to allocate char dev region\n",
__FILE__);
}
void __exit rtc_dev_exit(void)
{
if (rtc_devt)
unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
}