/*
 *      Real Time Clock interface for
 *              - q40 and other m68k machines,
 *              - HP PARISC machines
 *              - PowerPC machines
 *      emulate some RTC irq capabilities in software
 *
 *      Copyright (C) 1999 Richard Zidlicky
 *
 *      based on Paul Gortmaker's rtc.c device and
 *           Sam Creasey Generic rtc driver
 *
 *      This driver allows use of the real time clock (built into
 *      nearly all computers) from user space. It exports the /dev/rtc
 *      interface supporting various ioctl() and also the /proc/driver/rtc
 *      pseudo-file for status information.
 *
 *      The ioctls can be used to set the interrupt behaviour where
 *      supported.
 *
 *      The /dev/rtc interface will block on reads until an interrupt
 *      has been received. If a RTC interrupt has already happened,
 *      it will output an unsigned long and then block. The output value
 *      contains the interrupt status in the low byte and the number of
 *      interrupts since the last read in the remaining high bytes. The
 *      /dev/rtc interface can also be used with the select(2) call.
 *
 *      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.
 *

 *      1.01 fix for 2.3.X                    rz@linux-m68k.org
 *      1.02 merged with code from genrtc.c   rz@linux-m68k.org
 *      1.03 make it more portable            zippel@linux-m68k.org
 *      1.04 removed useless timer code       rz@linux-m68k.org
 *      1.05 portable RTC_UIE emulation       rz@linux-m68k.org
 *      1.06 set_rtc_time can return an error trini@kernel.crashing.org
 *      1.07 ported to HP PARISC (hppa)       Helge Deller <deller@gmx.de>
 */

#define RTC_VERSION     "1.07"

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>

#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/smp_lock.h>
#include <linux/workqueue.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/rtc.h>

/*
 *      We sponge a minor off of the misc major. No need slurping
 *      up another valuable major dev number for this. If you add
 *      an ioctl, make sure you don't conflict with SPARC's RTC
 *      ioctls.
 */

static DECLARE_WAIT_QUEUE_HEAD(gen_rtc_wait);

/*
 *      Bits in gen_rtc_status.
 */

#define RTC_IS_OPEN             0x01    /* means /dev/rtc is in use     */

static unsigned char gen_rtc_status;    /* bitmapped status byte.       */
static unsigned long gen_rtc_irq_data;  /* our output to the world      */

/* months start at 0 now */
static unsigned char days_in_mo[] =
{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

static int irq_active;

#ifdef CONFIG_GEN_RTC_X
static struct work_struct genrtc_task;
static struct timer_list timer_task;

static unsigned int oldsecs;
static int lostint;
static unsigned long tt_exp;

static void gen_rtc_timer(unsigned long data);

static volatile int stask_active;              /* schedule_work */
static volatile int ttask_active;              /* timer_task */
static int stop_rtc_timers;                    /* don't requeue tasks */
static DEFINE_SPINLOCK(gen_rtc_lock);

static void gen_rtc_interrupt(unsigned long arg);

/*
 * Routine to poll RTC seconds field for change as often as possible,
 * after first RTC_UIE use timer to reduce polling
 */
static void genrtc_troutine(struct work_struct *work)
{
        unsigned int tmp = get_rtc_ss();
        
        if (stop_rtc_timers) {
                stask_active = 0;
                return;
        }

        if (oldsecs != tmp){
                oldsecs = tmp;

                timer_task.function = gen_rtc_timer;
                timer_task.expires = jiffies + HZ - (HZ/10);
                tt_exp=timer_task.expires;
                ttask_active=1;
                stask_active=0;
                add_timer(&timer_task);

                gen_rtc_interrupt(0);
        } else if (schedule_work(&genrtc_task) == 0)
                stask_active = 0;
}

static void gen_rtc_timer(unsigned long data)
{
        lostint = get_rtc_ss() - oldsecs ;
        if (lostint<0) 
                lostint = 60 - lostint;
        if (time_after(jiffies, tt_exp))
                printk(KERN_INFO "genrtc: timer task delayed by %ld jiffies\n",
                       jiffies-tt_exp);
        ttask_active=0;
        stask_active=1;
        if ((schedule_work(&genrtc_task) == 0))
                stask_active = 0;
}

/* 
 * call gen_rtc_interrupt function to signal an RTC_UIE,
 * arg is unused.
 * Could be invoked either from a real interrupt handler or
 * from some routine that periodically (eg 100HZ) monitors
 * whether RTC_SECS changed
 */
static void gen_rtc_interrupt(unsigned long arg)
{
        /*  We store the status in the low byte and the number of
         *      interrupts received since the last read in the remainder
         *      of rtc_irq_data.  */

        gen_rtc_irq_data += 0x100;
        gen_rtc_irq_data &= ~0xff;
        gen_rtc_irq_data |= RTC_UIE;

        if (lostint){
                printk("genrtc: system delaying clock ticks?\n");
                /* increment count so that userspace knows something is wrong */
                gen_rtc_irq_data += ((lostint-1)<<8);
                lostint = 0;
        }

        wake_up_interruptible(&gen_rtc_wait);
}

/*
 *      Now all the various file operations that we export.
 */
static ssize_t gen_rtc_read(struct file *file, char __user *buf,
                        size_t count, loff_t *ppos)
{
        unsigned long data;
        ssize_t retval;

        if (count != sizeof (unsigned int) && count != sizeof (unsigned long))
                return -EINVAL;

        if (file->f_flags & O_NONBLOCK && !gen_rtc_irq_data)
                return -EAGAIN;

        retval = wait_event_interruptible(gen_rtc_wait,
                        (data = xchg(&gen_rtc_irq_data, 0)));
        if (retval)
                goto out;

        /* first test allows optimizer to nuke this case for 32-bit machines */
        if (sizeof (int) != sizeof (long) && count == sizeof (unsigned int)) {
                unsigned int uidata = data;
                retval = put_user(uidata, (unsigned int __user *)buf) ?:
                        sizeof(unsigned int);
        }
        else {
                retval = put_user(data, (unsigned long __user *)buf) ?:
                        sizeof(unsigned long);
        }
out:
        return retval;
}

static unsigned int gen_rtc_poll(struct file *file,
                                 struct poll_table_struct *wait)
{
        poll_wait(file, &gen_rtc_wait, wait);
        if (gen_rtc_irq_data != 0)
                return POLLIN | POLLRDNORM;
        return 0;
}

#endif

/*
 * Used to disable/enable interrupts, only RTC_UIE supported
 * We also clear out any old irq data after an ioctl() that
 * meddles with the interrupt enable/disable bits.
 */

static inline void gen_clear_rtc_irq_bit(unsigned char bit)
{
#ifdef CONFIG_GEN_RTC_X
        stop_rtc_timers = 1;
        if (ttask_active){
                del_timer_sync(&timer_task);
                ttask_active = 0;
        }
        while (stask_active)
                schedule();

        spin_lock(&gen_rtc_lock);
        irq_active = 0;
        spin_unlock(&gen_rtc_lock);
#endif
}

static inline int gen_set_rtc_irq_bit(unsigned char bit)
{
#ifdef CONFIG_GEN_RTC_X
        spin_lock(&gen_rtc_lock);
        if ( !irq_active ) {
                irq_active = 1;
                stop_rtc_timers = 0;
                lostint = 0;
                INIT_WORK(&genrtc_task, genrtc_troutine);
                oldsecs = get_rtc_ss();
                init_timer(&timer_task);

                stask_active = 1;
                if (schedule_work(&genrtc_task) == 0){
                        stask_active = 0;
                }
        }
        spin_unlock(&gen_rtc_lock);
        gen_rtc_irq_data = 0;
        return 0;
#else
        return -EINVAL;
#endif
}

static int gen_rtc_ioctl(struct inode *inode, struct file *file,
                         unsigned int cmd, unsigned long arg)
{
        struct rtc_time wtime;
        struct rtc_pll_info pll;
        void __user *argp = (void __user *)arg;

        switch (cmd) {

        case RTC_PLL_GET:
            if (get_rtc_pll(&pll))
                    return -EINVAL;
            else
                    return copy_to_user(argp, &pll, sizeof pll) ? -EFAULT : 0;

        case RTC_PLL_SET:
                if (!capable(CAP_SYS_TIME))
                        return -EACCES;
                if (copy_from_user(&pll, argp, sizeof(pll)))
                        return -EFAULT;
            return set_rtc_pll(&pll);

        case RTC_UIE_OFF:       /* disable ints from RTC updates.       */
                gen_clear_rtc_irq_bit(RTC_UIE);
                return 0;

        case RTC_UIE_ON:        /* enable ints for RTC updates. */
                return gen_set_rtc_irq_bit(RTC_UIE);

        case RTC_RD_TIME:       /* Read the time/date from RTC  */
                /* this doesn't get week-day, who cares */
                memset(&wtime, 0, sizeof(wtime));
                get_rtc_time(&wtime);

                return copy_to_user(argp, &wtime, sizeof(wtime)) ? -EFAULT : 0;

        case RTC_SET_TIME:      /* Set the RTC */
            {
                int year;
                unsigned char leap_yr;

                if (!capable(CAP_SYS_TIME))
                        return -EACCES;

                if (copy_from_user(&wtime, argp, sizeof(wtime)))
                        return -EFAULT;

                year = wtime.tm_year + 1900;
                leap_yr = ((!(year % 4) && (year % 100)) ||
                           !(year % 400));

                if ((wtime.tm_mon < 0 || wtime.tm_mon > 11) || (wtime.tm_mday < 1))
                        return -EINVAL;

                if (wtime.tm_mday < 0 || wtime.tm_mday >
                    (days_in_mo[wtime.tm_mon] + ((wtime.tm_mon == 1) && leap_yr)))
                        return -EINVAL;

                if (wtime.tm_hour < 0 || wtime.tm_hour >= 24 ||
                    wtime.tm_min < 0 || wtime.tm_min >= 60 ||
                    wtime.tm_sec < 0 || wtime.tm_sec >= 60)
                        return -EINVAL;

                return set_rtc_time(&wtime);
            }
        }

        return -EINVAL;
}

/*
 *      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 gen_rtc_open(struct inode *inode, struct file *file)
{
        lock_kernel();
        if (gen_rtc_status & RTC_IS_OPEN) {
                unlock_kernel();
                return -EBUSY;
        }

        gen_rtc_status |= RTC_IS_OPEN;
        gen_rtc_irq_data = 0;
        irq_active = 0;
        unlock_kernel();

        return 0;
}

static int gen_rtc_release(struct inode *inode, struct file *file)
{
        /*
         * Turn off all interrupts once the device is no longer
         * in use and clear the data.
         */

        gen_clear_rtc_irq_bit(RTC_PIE|RTC_AIE|RTC_UIE);

        gen_rtc_status &= ~RTC_IS_OPEN;
        return 0;
}


#ifdef CONFIG_PROC_FS

/*
 *      Info exported via "/proc/driver/rtc".
 */

static int gen_rtc_proc_output(char *buf)
{
        char *p;
        struct rtc_time tm;
        unsigned int flags;
        struct rtc_pll_info pll;

        p = buf;

        flags = get_rtc_time(&tm);

        p += sprintf(p,
                     "rtc_time\t: %02d:%02d:%02d\n"
                     "rtc_date\t: %04d-%02d-%02d\n"
                     "rtc_epoch\t: %04u\n",
                     tm.tm_hour, tm.tm_min, tm.tm_sec,
                     tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 1900);

        tm.tm_hour = tm.tm_min = tm.tm_sec = 0;

        p += sprintf(p, "alarm\t\t: ");
        if (tm.tm_hour <= 24)
                p += sprintf(p, "%02d:", tm.tm_hour);
        else
                p += sprintf(p, "**:");

        if (tm.tm_min <= 59)
                p += sprintf(p, "%02d:", tm.tm_min);
        else
                p += sprintf(p, "**:");

        if (tm.tm_sec <= 59)
                p += sprintf(p, "%02d\n", tm.tm_sec);
        else
                p += sprintf(p, "**\n");

        p += sprintf(p,
                     "DST_enable\t: %s\n"
                     "BCD\t\t: %s\n"
                     "24hr\t\t: %s\n"
                     "square_wave\t: %s\n"
                     "alarm_IRQ\t: %s\n"
                     "update_IRQ\t: %s\n"
                     "periodic_IRQ\t: %s\n"
                     "periodic_freq\t: %ld\n"
                     "batt_status\t: %s\n",
                     (flags & RTC_DST_EN) ? "yes" : "no",
                     (flags & RTC_DM_BINARY) ? "no" : "yes",
                     (flags & RTC_24H) ? "yes" : "no",
                     (flags & RTC_SQWE) ? "yes" : "no",
                     (flags & RTC_AIE) ? "yes" : "no",
                     irq_active ? "yes" : "no",
                     (flags & RTC_PIE) ? "yes" : "no",
                     0L /* freq */,
                     (flags & RTC_BATT_BAD) ? "bad" : "okay");
        if (!get_rtc_pll(&pll))
            p += sprintf(p,
                         "PLL adjustment\t: %d\n"
                         "PLL max +ve adjustment\t: %d\n"
                         "PLL max -ve adjustment\t: %d\n"
                         "PLL +ve adjustment factor\t: %d\n"
                         "PLL -ve adjustment factor\t: %d\n"
                         "PLL frequency\t: %ld\n",
                         pll.pll_value,
                         pll.pll_max,
                         pll.pll_min,
                         pll.pll_posmult,
                         pll.pll_negmult,
                         pll.pll_clock);
        return p - buf;
}

static int gen_rtc_read_proc(char *page, char **start, off_t off,
                             int count, int *eof, void *data)
{
        int len = gen_rtc_proc_output (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 gen_rtc_proc_init(void)
{
        struct proc_dir_entry *r;

        r = create_proc_read_entry("driver/rtc", 0, NULL, gen_rtc_read_proc, NULL);
        if (!r)
                return -ENOMEM;
        return 0;
}
#else
static inline int gen_rtc_proc_init(void) { return 0; }
#endif /* CONFIG_PROC_FS */


/*
 *      The various file operations we support.
 */

static const struct file_operations gen_rtc_fops = {
        .owner          = THIS_MODULE,
#ifdef CONFIG_GEN_RTC_X
        .read           = gen_rtc_read,
        .poll           = gen_rtc_poll,
#endif
        .ioctl          = gen_rtc_ioctl,
        .open           = gen_rtc_open,
        .release        = gen_rtc_release,
};

static struct miscdevice rtc_gen_dev =
{
        .minor          = RTC_MINOR,
        .name           = "rtc",
        .fops           = &gen_rtc_fops,
};

static int __init rtc_generic_init(void)
{
        int retval;

        printk(KERN_INFO "Generic RTC Driver v%s\n", RTC_VERSION);

        retval = misc_register(&rtc_gen_dev);
        if (retval < 0)
                return retval;

        retval = gen_rtc_proc_init();
        if (retval) {
                misc_deregister(&rtc_gen_dev);
                return retval;
        }

        return 0;
}

static void __exit rtc_generic_exit(void)
{
        remove_proc_entry ("driver/rtc", NULL);
        misc_deregister(&rtc_gen_dev);
}


module_init(rtc_generic_init);
module_exit(rtc_generic_exit);

MODULE_AUTHOR("Richard Zidlicky");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(RTC_MINOR);