linux-imx

/*

 * 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/init.h>

#include <linux/rtc.h>

#include <linux/proc_fs.h>

#include <linux/seq_file.h>

#include <linux/efi.h>

#include <linux/uaccess.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);

    }