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/*

 *      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/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/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)

{

        if (gen_rtc_status & RTC_IS_OPEN)

                return -EBUSY;

        gen_rtc_status |= RTC_IS_OPEN;

        gen_rtc_irq_data = 0;

        irq_active = 0;

        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);