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alistair23-linux/drivers/char/efirtc.c
John Kacur f29627c2a3 efirtc: explicitly set llseek to no_llseek 
Now that we've removed the BKL here, let's explicitly set llseek to
no_llseek since the default llseek is not used here.

The default_llseek function still contains the BKL.  When we are auditing
code to see if we can remove the BKL, this is one of the hidden
considerations we need to take into account.  i.e., is there
syncronization between code that has the BKL and llseek.

At the same time we remove the BKL it would be a good idea to do indicate
when no llseek function is required, so we don't have to revisit this code
again, when we are trying to determine if we can remove the BKL from the
default_llseek.

Signed-off-by: John Kacur <jkacur@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-16 07:19:59 -08:00

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/*
* EFI Time Services Driver for Linux
*
* Copyright (C) 1999 Hewlett-Packard Co
* Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
*
* Based on skeleton from the drivers/char/rtc.c driver by P. Gortmaker
*
* This code provides an architected & portable interface to the real time
* clock by using EFI instead of direct bit fiddling. The functionalities are
* quite different from the rtc.c driver. The only way to talk to the device
* is by using ioctl(). There is a /proc interface which provides the raw
* information.
*
* Please note that we have kept the API as close as possible to the
* legacy RTC. The standard /sbin/hwclock program should work normally
* when used to get/set the time.
*
* NOTES:
* - Locking is required for safe execution of EFI calls with regards
* to interrupts and SMP.
*
* TODO (December 1999):
* - provide the API to set/get the WakeUp Alarm (different from the
* rtc.c alarm).
* - SMP testing
* - Add module support
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/proc_fs.h>
#include <linux/efi.h>
#include <linux/uaccess.h>
#include <asm/system.h>
#define EFI_RTC_VERSION "0.4"
#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
/*
* EFI Epoch is 1/1/1998
*/
#define EFI_RTC_EPOCH 1998
static DEFINE_SPINLOCK(efi_rtc_lock);
static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
#define is_leap(year) \
((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
static const unsigned short int __mon_yday[2][13] =
{
/* Normal years. */
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
/* Leap years. */
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
/*
* returns day of the year [0-365]
*/
static inline int
compute_yday(efi_time_t *eft)
{
/* efi_time_t.month is in the [1-12] so, we need -1 */
return __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
}
/*
* returns day of the week [0-6] 0=Sunday
*
* Don't try to provide a year that's before 1998, please !
*/
static int
compute_wday(efi_time_t *eft)
{
int y;
int ndays = 0;
if ( eft->year < 1998 ) {
printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
return -1;
}
for(y=EFI_RTC_EPOCH; y < eft->year; y++ ) {
ndays += 365 + (is_leap(y) ? 1 : 0);
}
ndays += compute_yday(eft);
/*
* 4=1/1/1998 was a Thursday
*/
return (ndays + 4) % 7;
}
static void
convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
{
eft->year = wtime->tm_year + 1900;
eft->month = wtime->tm_mon + 1;
eft->day = wtime->tm_mday;
eft->hour = wtime->tm_hour;
eft->minute = wtime->tm_min;
eft->second = wtime->tm_sec;
eft->nanosecond = 0;
eft->daylight = wtime->tm_isdst ? EFI_ISDST: 0;
eft->timezone = EFI_UNSPECIFIED_TIMEZONE;
}
static void
convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
{
memset(wtime, 0, sizeof(*wtime));
wtime->tm_sec = eft->second;
wtime->tm_min = eft->minute;
wtime->tm_hour = eft->hour;
wtime->tm_mday = eft->day;
wtime->tm_mon = eft->month - 1;
wtime->tm_year = eft->year - 1900;
/* day of the week [0-6], Sunday=0 */
wtime->tm_wday = compute_wday(eft);
/* day in the year [1-365]*/
wtime->tm_yday = compute_yday(eft);
switch (eft->daylight & EFI_ISDST) {
case EFI_ISDST:
wtime->tm_isdst = 1;
break;
case EFI_TIME_ADJUST_DAYLIGHT:
wtime->tm_isdst = 0;
break;
default:
wtime->tm_isdst = -1;
}
}
static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
efi_status_t status;
unsigned long flags;
efi_time_t eft;
efi_time_cap_t cap;
struct rtc_time wtime;
struct rtc_wkalrm __user *ewp;
unsigned char enabled, pending;
switch (cmd) {
case RTC_UIE_ON:
case RTC_UIE_OFF:
case RTC_PIE_ON:
case RTC_PIE_OFF:
case RTC_AIE_ON:
case RTC_AIE_OFF:
case RTC_ALM_SET:
case RTC_ALM_READ:
case RTC_IRQP_READ:
case RTC_IRQP_SET:
case RTC_EPOCH_READ:
case RTC_EPOCH_SET:
return -EINVAL;
case RTC_RD_TIME:
spin_lock_irqsave(&efi_rtc_lock, flags);
status = efi.get_time(&eft, &cap);
spin_unlock_irqrestore(&efi_rtc_lock,flags);
if (status != EFI_SUCCESS) {
/* should never happen */
printk(KERN_ERR "efitime: can't read time\n");
return -EINVAL;
}
convert_from_efi_time(&eft, &wtime);
return copy_to_user((void __user *)arg, &wtime,
sizeof (struct rtc_time)) ? - EFAULT : 0;
case RTC_SET_TIME:
if (!capable(CAP_SYS_TIME)) return -EACCES;
if (copy_from_user(&wtime, (struct rtc_time __user *)arg,
sizeof(struct rtc_time)) )
return -EFAULT;
convert_to_efi_time(&wtime, &eft);
spin_lock_irqsave(&efi_rtc_lock, flags);
status = efi.set_time(&eft);
spin_unlock_irqrestore(&efi_rtc_lock,flags);
return status == EFI_SUCCESS ? 0 : -EINVAL;
case RTC_WKALM_SET:
if (!capable(CAP_SYS_TIME)) return -EACCES;
ewp = (struct rtc_wkalrm __user *)arg;
if ( get_user(enabled, &ewp->enabled)
|| copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
return -EFAULT;
convert_to_efi_time(&wtime, &eft);
spin_lock_irqsave(&efi_rtc_lock, flags);
/*
* XXX Fixme:
* As of EFI 0.92 with the firmware I have on my
* machine this call does not seem to work quite
* right
*/
status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);
spin_unlock_irqrestore(&efi_rtc_lock,flags);
return status == EFI_SUCCESS ? 0 : -EINVAL;
case RTC_WKALM_RD:
spin_lock_irqsave(&efi_rtc_lock, flags);
status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);
spin_unlock_irqrestore(&efi_rtc_lock,flags);
if (status != EFI_SUCCESS) return -EINVAL;
ewp = (struct rtc_wkalrm __user *)arg;
if ( put_user(enabled, &ewp->enabled)
|| put_user(pending, &ewp->pending)) return -EFAULT;
convert_from_efi_time(&eft, &wtime);
return copy_to_user(&ewp->time, &wtime,
sizeof(struct rtc_time)) ? -EFAULT : 0;
}
return -ENOTTY;
}
/*
* We enforce only one user at a time here with the open/close.
* Also clear the previous interrupt data on an open, and clean
* up things on a close.
*/
static int efi_rtc_open(struct inode *inode, struct file *file)
{
/*
* nothing special to do here
* We do accept multiple open files at the same time as we
* synchronize on the per call operation.
*/
return 0;
}
static int efi_rtc_close(struct inode *inode, struct file *file)
{
return 0;
}
/*
* The various file operations we support.
*/
static const struct file_operations efi_rtc_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = efi_rtc_ioctl,
.open = efi_rtc_open,
.release = efi_rtc_close,
.llseek = no_llseek,
};
static struct miscdevice efi_rtc_dev= {
EFI_RTC_MINOR,
"efirtc",
&efi_rtc_fops
};
/*
* We export RAW EFI information to /proc/driver/efirtc
*/
static int
efi_rtc_get_status(char *buf)
{
efi_time_t eft, alm;
efi_time_cap_t cap;
char *p = buf;
efi_bool_t enabled, pending;
unsigned long flags;
memset(&eft, 0, sizeof(eft));
memset(&alm, 0, sizeof(alm));
memset(&cap, 0, sizeof(cap));
spin_lock_irqsave(&efi_rtc_lock, flags);
efi.get_time(&eft, &cap);
efi.get_wakeup_time(&enabled, &pending, &alm);
spin_unlock_irqrestore(&efi_rtc_lock,flags);
p += sprintf(p,
"Time : %u:%u:%u.%09u\n"
"Date : %u-%u-%u\n"
"Daylight : %u\n",
eft.hour, eft.minute, eft.second, eft.nanosecond,
eft.year, eft.month, eft.day,
eft.daylight);
if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
p += sprintf(p, "Timezone : unspecified\n");
else
/* XXX fixme: convert to string? */
p += sprintf(p, "Timezone : %u\n", eft.timezone);
p += sprintf(p,
"Alarm Time : %u:%u:%u.%09u\n"
"Alarm Date : %u-%u-%u\n"
"Alarm Daylight : %u\n"
"Enabled : %s\n"
"Pending : %s\n",
alm.hour, alm.minute, alm.second, alm.nanosecond,
alm.year, alm.month, alm.day,
alm.daylight,
enabled == 1 ? "yes" : "no",
pending == 1 ? "yes" : "no");
if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
p += sprintf(p, "Timezone : unspecified\n");
else
/* XXX fixme: convert to string? */
p += sprintf(p, "Timezone : %u\n", alm.timezone);
/*
* now prints the capabilities
*/
p += sprintf(p,
"Resolution : %u\n"
"Accuracy : %u\n"
"SetstoZero : %u\n",
cap.resolution, cap.accuracy, cap.sets_to_zero);
return p - buf;
}
static int
efi_rtc_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int len = efi_rtc_get_status(page);
if (len <= off+count) *eof = 1;
*start = page + off;
len -= off;
if (len>count) len = count;
if (len<0) len = 0;
return len;
}
static int __init
efi_rtc_init(void)
{
int ret;
struct proc_dir_entry *dir;
printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
ret = misc_register(&efi_rtc_dev);
if (ret) {
printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
EFI_RTC_MINOR);
return ret;
}
dir = create_proc_read_entry ("driver/efirtc", 0, NULL,
efi_rtc_read_proc, NULL);
if (dir == NULL) {
printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
misc_deregister(&efi_rtc_dev);
return -1;
}
return 0;
}
static void __exit
efi_rtc_exit(void)
{
/* not yet used */
}
module_init(efi_rtc_init);
module_exit(efi_rtc_exit);
MODULE_LICENSE("GPL");
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