/*
 * 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");