genrtc.c

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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                    [email protected]
 *      1.02 merged with code from genrtc.c   [email protected]
 *      1.03 make it more portable            [email protected]
 *      1.04 removed useless timer code       [email protected]
 *      1.05 portable RTC_UIE emulation       [email protected]
 *      1.06 set_rtc_time can return an error [email protected]
 *      1.07 ported to HP PARISC (hppa)       Helge Deller <[email protected]>
 */

#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/mutex.h>
#include <linux/workqueue.h>

#include <asm/uaccess.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 DEFINE_MUTEX(gen_rtc_mutex);
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 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;
}

static long gen_rtc_unlocked_ioctl(struct file *file, unsigned int cmd,
                   unsigned long arg)
{
    int ret;

    mutex_lock(&gen_rtc_mutex);
    ret = gen_rtc_ioctl(file, cmd, arg);
    mutex_unlock(&gen_rtc_mutex);

    return ret;
}

/*
 *  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)
{
    mutex_lock(&gen_rtc_mutex);
    if (gen_rtc_status & RTC_IS_OPEN) {
        mutex_unlock(&gen_rtc_mutex);
        return -EBUSY;
    }

    gen_rtc_status |= RTC_IS_OPEN;
    gen_rtc_irq_data = 0;
    irq_active = 0;
    mutex_unlock(&gen_rtc_mutex);

    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
    .unlocked_ioctl = gen_rtc_unlocked_ioctl,
    .open       = gen_rtc_open,
    .release    = gen_rtc_release,
    .llseek     = noop_llseek,
};

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);