linux/drivers/char/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 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/seq_file.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_show(struct seq_file *m, void *v)
{
struct rtc_time tm;
unsigned int flags;
struct rtc_pll_info pll;
flags = get_rtc_time(&tm);
seq_printf(m,
"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;
seq_puts(m, "alarm\t\t: ");
if (tm.tm_hour <= 24)
seq_printf(m, "%02d:", tm.tm_hour);
else
seq_puts(m, "**:");
if (tm.tm_min <= 59)
seq_printf(m, "%02d:", tm.tm_min);
else
seq_puts(m, "**:");
if (tm.tm_sec <= 59)
seq_printf(m, "%02d\n", tm.tm_sec);
else
seq_puts(m, "**\n");
seq_printf(m,
"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))
seq_printf(m,
"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 0;
}
static int gen_rtc_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, gen_rtc_proc_show, NULL);
}
static const struct file_operations gen_rtc_proc_fops = {
.open = gen_rtc_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int __init gen_rtc_proc_init(void)
{
struct proc_dir_entry *r;
r = proc_create("driver/rtc", 0, NULL, &gen_rtc_proc_fops);
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: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 16:52:59 +00:00
.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);