/*
* Real Time Clock interface for Linux
*
* Copyright (C) 1996 Paul Gortmaker
*
* 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/rtc
* pseudo-file for status information.
*
* The ioctls can be used to set the interrupt behaviour and
* generation rate from the RTC via IRQ 8. Then the /dev/rtc
* interface can be used to make use of these timer interrupts,
* be they interval or alarm based.
*
* 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.
*
* Based on other minimal char device drivers, like Alan's
* watchdog, Ted's random, etc. etc.
*
*/
#define RTC_VERSION "1.07"
#define RTC_IRQ 8 /* Can't see this changing soon. */
#define RTC_IO_EXTENT 0x10 /* Only really two ports, but... */
/*
* Note that *all* calls to CMOS_READ and CMOS_WRITE are done with
* interrupts disabled. Due to the index-port/data-port (0x70/0x71)
* design of the RTC, we don't want two different things trying to
* get to it at once. (e.g. the periodic 11 min sync from time.c vs.
* this driver.)
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/malloc.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/mc146818rtc.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <asm/system.h>
/*
* We sponge a minor off of the misc major. No need slurping
* up another valuable major dev number for this.
*/
#define RTC_MINOR 135
static struct wait_queue *rtc_wait;
static struct timer_list rtc_irq_timer;
static int rtc_lseek(struct inode *inode, struct file *file, off_t offset,
int origin);
static int rtc_read(struct inode *inode, struct file *file,
char *buf, int count);
static int rtc_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg);
static int rtc_select(struct inode *inode, struct file *file,
int sel_type, select_table *wait);
void get_rtc_time (struct rtc_time *rtc_tm);
void get_rtc_alm_time (struct rtc_time *alm_tm);
void rtc_dropped_irq(unsigned long data);
void set_rtc_irq_bit(unsigned char bit);
void mask_rtc_irq_bit(unsigned char bit);
static inline unsigned char rtc_is_updating(void);
/*
* Bits in rtc_status. (7 bits of room for future expansion)
*/
#define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
#define RTC_TIMER_ON 0x02 /* missed irq timer active */
unsigned char rtc_status = 0; /* bitmapped status byte. */
unsigned long rtc_freq = 0; /* Current periodic IRQ rate */
unsigned long rtc_irq_data = 0; /* our output to the world */
unsigned char days_in_mo[] =
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
/*
* A very tiny interrupt handler. It runs with SA_INTERRUPT set,
* so that there is no possibility of conflicting with the
* set_rtc_mmss() call that happens during some timer interrupts.
* (See ./arch/XXXX/kernel/time.c for the set_rtc_mmss() function.)
*/
static void rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
/*
* Can be an alarm interrupt, update complete interrupt,
* or a periodic interrupt. 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.
*/
rtc_irq_data += 0x100;
rtc_irq_data &= ~0xff;
rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0);
wake_up_interruptible(&rtc_wait);
if (rtc_status & RTC_TIMER_ON) {
del_timer(&rtc_irq_timer);
rtc_irq_timer.expires = jiffies + HZ/rtc_freq + 2*HZ/100;
add_timer(&rtc_irq_timer);
}
}
/*
* Now all the various file operations that we export.
*/
static int rtc_lseek(struct inode *inode, struct file *file, off_t offset,
int origin)
{
return -ESPIPE;
}
static int rtc_read(struct inode *inode, struct file *file, char *buf, int count)
{
struct wait_queue wait = { current, NULL };
int retval;
if (count < sizeof(unsigned long))
return -EINVAL;
retval = verify_area(VERIFY_WRITE, buf, sizeof(unsigned long));
if (retval)
return retval;
add_wait_queue(&rtc_wait, &wait);
current->state = TASK_INTERRUPTIBLE;
while (rtc_irq_data == 0) {
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (current->signal & ~current->blocked) {
retval = -ERESTARTSYS;
break;
}
schedule();
}
if (retval == 0) {
unsigned long data, flags;
save_flags(flags);
cli();
data = rtc_irq_data;
rtc_irq_data = 0;
restore_flags(flags);
memcpy_tofs(buf, &data, sizeof(unsigned long));
retval = sizeof(unsigned long);
}
current->state = TASK_RUNNING;
remove_wait_queue(&rtc_wait, &wait);
return retval;
}
static int rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
unsigned long flags;
switch (cmd) {
case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
{
mask_rtc_irq_bit(RTC_AIE);
return 0;
}
case RTC_AIE_ON: /* Allow alarm interrupts. */
{
set_rtc_irq_bit(RTC_AIE);
return 0;
}
case RTC_PIE_OFF: /* Mask periodic int. enab. bit */
{
mask_rtc_irq_bit(RTC_PIE);
if (rtc_status & RTC_TIMER_ON) {
del_timer(&rtc_irq_timer);
rtc_status &= ~RTC_TIMER_ON;
}
return 0;
}
case RTC_PIE_ON: /* Allow periodic ints */
{
/*
* We don't really want Joe User enabling more
* than 64Hz of interrupts on a multi-user machine.
*/
if ((rtc_freq > 64) && (!suser()))
return -EACCES;
if (!(rtc_status & RTC_TIMER_ON)) {
rtc_status |= RTC_TIMER_ON;
rtc_irq_timer.expires = jiffies + HZ/rtc_freq + 2*HZ/100;
add_timer(&rtc_irq_timer);
}
set_rtc_irq_bit(RTC_PIE);
return 0;
}
case RTC_UIE_OFF: /* Mask ints from RTC updates. */
{
mask_rtc_irq_bit(RTC_UIE);
return 0;
}
case RTC_UIE_ON: /* Allow ints for RTC updates. */
{
set_rtc_irq_bit(RTC_UIE);
return 0;
}
case RTC_ALM_READ: /* Read the present alarm time */
{
/*
* This returns a struct rtc_time. Reading >= 0xc0
* means "don't care" or "match all". Only the tm_hour,
* tm_min, and tm_sec values are filled in.
*/
int retval;
struct rtc_time alm_tm;
retval = verify_area(VERIFY_WRITE, (struct rtc_time*)arg, sizeof(struct rtc_time));
if (retval != 0 )
return retval;
get_rtc_alm_time(&alm_tm);
memcpy_tofs((struct rtc_time*)arg, &alm_tm, sizeof(struct rtc_time));
return 0;
}
case RTC_ALM_SET: /* Store a time into the alarm */
{
/*
* This expects a struct rtc_time. Writing 0xff means
* "don't care" or "match all". Only the tm_hour,
* tm_min and tm_sec are used.
*/
int retval;
unsigned char hrs, min, sec;
struct rtc_time alm_tm;
retval = verify_area(VERIFY_READ, (struct rtc_time*)arg, sizeof(struct rtc_time));
if (retval != 0 )
return retval;
memcpy_fromfs(&alm_tm, (struct rtc_time*)arg, sizeof(struct rtc_time));
hrs = alm_tm.tm_hour;
min = alm_tm.tm_min;
sec = alm_tm.tm_sec;
if (hrs >= 24)
hrs = 0xff;
if (min >= 60)
min = 0xff;
if (sec >= 60)
sec = 0xff;
save_flags(flags);
cli();
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
RTC_ALWAYS_BCD)
{
BIN_TO_BCD(sec);
BIN_TO_BCD(min);
BIN_TO_BCD(hrs);
}
CMOS_WRITE(hrs, RTC_HOURS_ALARM);
CMOS_WRITE(min, RTC_MINUTES_ALARM);
CMOS_WRITE(sec, RTC_SECONDS_ALARM);
restore_flags(flags);
return 0;
}
case RTC_RD_TIME: /* Read the time/date from RTC */
{
int retval;
struct rtc_time rtc_tm;
retval = verify_area(VERIFY_WRITE, (struct rtc_time*)arg, sizeof(struct rtc_time));
if (retval !=0 )
return retval;
get_rtc_time(&rtc_tm);
memcpy_tofs((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time));
return 0;
}
case RTC_SET_TIME: /* Set the RTC */
{
int retval;
struct rtc_time rtc_tm;
unsigned char mon, day, hrs, min, sec, leap_yr;
unsigned char save_control, save_freq_select;
unsigned int yrs;
unsigned long flags;
if (!suser())
return -EACCES;
retval = verify_area(VERIFY_READ, (struct rtc_time*)arg, sizeof(struct rtc_time));
if (retval !=0 )
return retval;
memcpy_fromfs(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time));
yrs = rtc_tm.tm_year + 1900;
mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
day = rtc_tm.tm_mday;
hrs = rtc_tm.tm_hour;
min = rtc_tm.tm_min;
sec = rtc_tm.tm_sec;
if ((yrs < 1970) || (yrs > 2069))
return -EINVAL;
leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
if ((mon > 12) || (day == 0))
return -EINVAL;
if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
return -EINVAL;
if ((hrs >= 24) || (min >= 60) || (sec >= 60))
return -EINVAL;
if (yrs >= 2000)
yrs -= 2000; /* RTC (0, 1, ... 69) */
else
yrs -= 1900; /* RTC (70, 71, ... 99) */
save_flags(flags);
cli();
if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) ||
RTC_ALWAYS_BCD)
{
BIN_TO_BCD(sec);
BIN_TO_BCD(min);
BIN_TO_BCD(hrs);
BIN_TO_BCD(day);
BIN_TO_BCD(mon);
BIN_TO_BCD(yrs);
}
save_control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
CMOS_WRITE(yrs, RTC_YEAR);
CMOS_WRITE(mon, RTC_MONTH);
CMOS_WRITE(day, RTC_DAY_OF_MONTH);
CMOS_WRITE(hrs, RTC_HOURS);
CMOS_WRITE(min, RTC_MINUTES);
CMOS_WRITE(sec, RTC_SECONDS);
CMOS_WRITE(save_control, RTC_CONTROL);
CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
restore_flags(flags);
return 0;
}
case RTC_IRQP_READ: /* Read the periodic IRQ rate. */
{
int retval;
retval = verify_area(VERIFY_WRITE, (unsigned long*)arg, sizeof(unsigned long));
if (retval != 0)
return retval;
memcpy_tofs((unsigned long*)arg, &rtc_freq, sizeof(unsigned long));
return 0;
}
case RTC_IRQP_SET: /* Set periodic IRQ rate. */
{
int tmp = 0;
unsigned char val;
/*
* The max we can do is 8192Hz.
*/
if ((arg < 2) || (arg > 8192))
return -EINVAL;
/*
* We don't really want Joe User generating more
* than 64Hz of interrupts on a multi-user machine.
*/
if ((arg > 64) && (!suser()))
return -EACCES;
while (arg > (1<<tmp))
tmp++;
/*
* Check that the input was really a power of 2.
*/
if (arg != (1<<tmp))
return -EINVAL;
rtc_freq = arg;
save_flags(flags);
cli();
val = CMOS_READ(RTC_FREQ_SELECT) & 0xf0;
val |= (16 - tmp);
CMOS_WRITE(val, RTC_FREQ_SELECT);
restore_flags(flags);
return 0;
}
default:
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 rtc_open(struct inode *inode, struct file *file)
{
if(rtc_status & RTC_IS_OPEN)
return -EBUSY;
rtc_status |= RTC_IS_OPEN;
rtc_irq_data = 0;
return 0;
}
static void rtc_release(struct inode *inode, struct file *file)
{
/*
* Turn off all interrupts once the device is no longer
* in use, and clear the data.
*/
unsigned char tmp;
unsigned long flags;
save_flags(flags);
cli();
tmp = CMOS_READ(RTC_CONTROL);
tmp &= ~RTC_PIE;
tmp &= ~RTC_AIE;
tmp &= ~RTC_UIE;
CMOS_WRITE(tmp, RTC_CONTROL);
CMOS_READ(RTC_INTR_FLAGS);
restore_flags(flags);
if (rtc_status & RTC_TIMER_ON) {
rtc_status &= ~RTC_TIMER_ON;
del_timer(&rtc_irq_timer);
}
rtc_irq_data = 0;
rtc_status &= ~RTC_IS_OPEN;
}
static int rtc_select(struct inode *inode, struct file *file,
int sel_type, select_table *wait)
{
if (sel_type == SEL_IN) {
if (rtc_irq_data != 0)
return 1;
select_wait(&rtc_wait, wait);
}
return 0;
}
/*
* The various file operations we support.
*/
static struct file_operations rtc_fops = {
rtc_lseek,
rtc_read,
NULL, /* No write */
NULL, /* No readdir */
rtc_select,
rtc_ioctl,
NULL, /* No mmap */
rtc_open,
rtc_release
};
static struct miscdevice rtc_dev=
{
RTC_MINOR,
"rtc",
&rtc_fops
};
int rtc_init(void)
{
unsigned long flags;
printk("Real Time Clock Driver v%s\n", RTC_VERSION);
if(request_irq(RTC_IRQ, rtc_interrupt, SA_INTERRUPT, "rtc", NULL))
{
/* Yeah right, seeing as irq 8 doesn't even hit the bus. */
printk("rtc: IRQ %d is not free.\n", RTC_IRQ);
return -EIO;
}
misc_register(&rtc_dev);
/* Check region? Naaah! Just snarf it up. */
request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
init_timer(&rtc_irq_timer);
rtc_irq_timer.function = rtc_dropped_irq;
rtc_wait = NULL;
save_flags(flags);
cli();
/* Initialize periodic freq. to CMOS reset default, which is 1024Hz */
CMOS_WRITE(((CMOS_READ(RTC_FREQ_SELECT) & 0xF0) | 0x06), RTC_FREQ_SELECT);
restore_flags(flags);
rtc_freq = 1024;
return 0;
}
/*
* At IRQ rates >= 4096Hz, an interrupt may get lost altogether.
* (usually during an IDE disk interrupt, with IRQ unmasking off)
* Since the interrupt handler doesn't get called, the IRQ status
* byte doesn't get read, and the RTC stops generating interrupts.
* A timer is set, and will call this function if/when that happens.
* To get it out of this stalled state, we just read the status.
* At least a jiffy of interrupts (rtc_freq/HZ) will have been lost.
* (You *really* shouldn't be trying to use a non-realtime system
* for something that requires a steady > 1KHz signal anyways.)
*/
void rtc_dropped_irq(unsigned long data)
{
unsigned long flags;
printk(KERN_INFO "rtc: lost some interrupts at %ldHz.\n", rtc_freq);
del_timer(&rtc_irq_timer);
rtc_irq_timer.expires = jiffies + HZ/rtc_freq + 2*HZ/100;
add_timer(&rtc_irq_timer);
save_flags(flags);
cli();
rtc_irq_data += ((rtc_freq/HZ)<<8);
rtc_irq_data &= ~0xff;
rtc_irq_data |= (CMOS_READ(RTC_INTR_FLAGS) & 0xF0); /* restart */
restore_flags(flags);
}
/*
* Info exported via "/proc/rtc".
*/
int get_rtc_status(char *buf)
{
char *p;
struct rtc_time tm;
unsigned char batt, ctrl;
unsigned long flags;
save_flags(flags);
cli();
batt = CMOS_READ(RTC_VALID) & RTC_VRT;
ctrl = CMOS_READ(RTC_CONTROL);
restore_flags(flags);
p = buf;
get_rtc_time(&tm);
/*
* There is no way to tell if the luser has the RTC set for local
* time or for Universal Standard Time (GMT). Probably local though.
*/
p += sprintf(p,
"rtc_time\t: %02d:%02d:%02d\n"
"rtc_date\t: %04d-%02d-%02d\n",
tm.tm_hour, tm.tm_min, tm.tm_sec,
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
get_rtc_alm_time(&tm);
/*
* We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
* match any value for that particular field. Values that are
* greater than a valid time, but less than 0xc0 shouldn't appear.
*/
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",
(ctrl & RTC_DST_EN) ? "yes" : "no",
(ctrl & RTC_DM_BINARY) ? "no" : "yes",
(ctrl & RTC_24H) ? "yes" : "no",
(ctrl & RTC_SQWE) ? "yes" : "no",
(ctrl & RTC_AIE) ? "yes" : "no",
(ctrl & RTC_UIE) ? "yes" : "no",
(ctrl & RTC_PIE) ? "yes" : "no",
rtc_freq,
batt ? "okay" : "dead");
return p - buf;
}
/*
* Returns true if a clock update is in progress
*/
static inline unsigned char rtc_is_updating(void)
{
unsigned long flags;
unsigned char uip;
save_flags(flags);
cli();
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
restore_flags(flags);
return uip;
}
void get_rtc_time(struct rtc_time *rtc_tm)
{
unsigned long flags, uip_watchdog = jiffies;
unsigned char ctrl;
/*
* read RTC once any update in progress is done. The update
* can take just over 2ms. We wait 10 to 20ms. There is no need to
* to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
* If you need to know *exactly* when a second has started, enable
* periodic update complete interrupts, (via ioctl) and then
* immediately read /dev/rtc which will block until you get the IRQ.
* Once the read clears, read the RTC time (again via ioctl). Easy.
*/
if (rtc_is_updating() != 0)
while (jiffies - uip_watchdog < 2*HZ/100)
barrier();
/*
* Only the values that we read from the RTC are set. We leave
* tm_wday, tm_yday and tm_isdst untouched. Even though the
* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
* by the RTC when initially set to a non-zero value.
*/
save_flags(flags);
cli();
rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
ctrl = CMOS_READ(RTC_CONTROL);
restore_flags(flags);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
BCD_TO_BIN(rtc_tm->tm_sec);
BCD_TO_BIN(rtc_tm->tm_min);
BCD_TO_BIN(rtc_tm->tm_hour);
BCD_TO_BIN(rtc_tm->tm_mday);
BCD_TO_BIN(rtc_tm->tm_mon);
BCD_TO_BIN(rtc_tm->tm_year);
}
/*
* Account for differences between how the RTC uses the values
* and how they are defined in a struct rtc_time;
*/
if (rtc_tm->tm_year <= 69)
rtc_tm->tm_year += 100;
rtc_tm->tm_mon--;
}
void get_rtc_alm_time(struct rtc_time *alm_tm)
{
unsigned long flags;
unsigned char ctrl;
/*
* Only the values that we read from the RTC are set. That
* means only tm_hour, tm_min, and tm_sec.
*/
save_flags(flags);
cli();
alm_tm->tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM);
alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM);
ctrl = CMOS_READ(RTC_CONTROL);
restore_flags(flags);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
{
BCD_TO_BIN(alm_tm->tm_sec);
BCD_TO_BIN(alm_tm->tm_min);
BCD_TO_BIN(alm_tm->tm_hour);
}
}
/*
* Used to disable/enable interrupts for any one of UIE, AIE, PIE.
* Rumour has it that if you frob the interrupt enable/disable
* bits in RTC_CONTROL, you should read RTC_INTR_FLAGS, to
* ensure you actually start getting interrupts. Probably for
* compatibility with older/broken chipset RTC implementations.
* We also clear out any old irq data after an ioctl() that
* meddles with the interrupt enable/disable bits.
*/
void mask_rtc_irq_bit(unsigned char bit)
{
unsigned char val;
unsigned long flags;
save_flags(flags);
cli();
val = CMOS_READ(RTC_CONTROL);
val &= ~bit;
CMOS_WRITE(val, RTC_CONTROL);
CMOS_READ(RTC_INTR_FLAGS);
restore_flags(flags);
rtc_irq_data = 0;
}
void set_rtc_irq_bit(unsigned char bit)
{
unsigned char val;
unsigned long flags;
save_flags(flags);
cli();
val = CMOS_READ(RTC_CONTROL);
val |= bit;
CMOS_WRITE(val, RTC_CONTROL);
CMOS_READ(RTC_INTR_FLAGS);
rtc_irq_data = 0;
restore_flags(flags);
}
