kernel/time/clocksource.c needs struct task_struct on m68k. Because it uses spin_unlock_irq(), which, on m68k, uses hardirq_count(), which uses preempt_count(), which needs to dereference struct task_struct, we have to include sched.h. Because it would cause a loop inclusion, we cannot include sched.h in any other of asm-m68k/system.h, linux/thread_info.h, linux/hardirq.h, which leaves this ugly include in a C file as the only simple solution. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
352 lines
9 KiB
C
352 lines
9 KiB
C
/*
|
|
* linux/kernel/time/clocksource.c
|
|
*
|
|
* This file contains the functions which manage clocksource drivers.
|
|
*
|
|
* Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com)
|
|
*
|
|
* 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.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*
|
|
* TODO WishList:
|
|
* o Allow clocksource drivers to be unregistered
|
|
* o get rid of clocksource_jiffies extern
|
|
*/
|
|
|
|
#include <linux/clocksource.h>
|
|
#include <linux/sysdev.h>
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
|
|
|
|
/* XXX - Would like a better way for initializing curr_clocksource */
|
|
extern struct clocksource clocksource_jiffies;
|
|
|
|
/*[Clocksource internal variables]---------
|
|
* curr_clocksource:
|
|
* currently selected clocksource. Initialized to clocksource_jiffies.
|
|
* next_clocksource:
|
|
* pending next selected clocksource.
|
|
* clocksource_list:
|
|
* linked list with the registered clocksources
|
|
* clocksource_lock:
|
|
* protects manipulations to curr_clocksource and next_clocksource
|
|
* and the clocksource_list
|
|
* override_name:
|
|
* Name of the user-specified clocksource.
|
|
*/
|
|
static struct clocksource *curr_clocksource = &clocksource_jiffies;
|
|
static struct clocksource *next_clocksource;
|
|
static LIST_HEAD(clocksource_list);
|
|
static DEFINE_SPINLOCK(clocksource_lock);
|
|
static char override_name[32];
|
|
static int finished_booting;
|
|
|
|
/* clocksource_done_booting - Called near the end of bootup
|
|
*
|
|
* Hack to avoid lots of clocksource churn at boot time
|
|
*/
|
|
static int __init clocksource_done_booting(void)
|
|
{
|
|
finished_booting = 1;
|
|
return 0;
|
|
}
|
|
|
|
late_initcall(clocksource_done_booting);
|
|
|
|
/**
|
|
* clocksource_get_next - Returns the selected clocksource
|
|
*
|
|
*/
|
|
struct clocksource *clocksource_get_next(void)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&clocksource_lock, flags);
|
|
if (next_clocksource && finished_booting) {
|
|
curr_clocksource = next_clocksource;
|
|
next_clocksource = NULL;
|
|
}
|
|
spin_unlock_irqrestore(&clocksource_lock, flags);
|
|
|
|
return curr_clocksource;
|
|
}
|
|
|
|
/**
|
|
* select_clocksource - Finds the best registered clocksource.
|
|
*
|
|
* Private function. Must hold clocksource_lock when called.
|
|
*
|
|
* Looks through the list of registered clocksources, returning
|
|
* the one with the highest rating value. If there is a clocksource
|
|
* name that matches the override string, it returns that clocksource.
|
|
*/
|
|
static struct clocksource *select_clocksource(void)
|
|
{
|
|
struct clocksource *best = NULL;
|
|
struct list_head *tmp;
|
|
|
|
list_for_each(tmp, &clocksource_list) {
|
|
struct clocksource *src;
|
|
|
|
src = list_entry(tmp, struct clocksource, list);
|
|
if (!best)
|
|
best = src;
|
|
|
|
/* check for override: */
|
|
if (strlen(src->name) == strlen(override_name) &&
|
|
!strcmp(src->name, override_name)) {
|
|
best = src;
|
|
break;
|
|
}
|
|
/* pick the highest rating: */
|
|
if (src->rating > best->rating)
|
|
best = src;
|
|
}
|
|
|
|
return best;
|
|
}
|
|
|
|
/**
|
|
* is_registered_source - Checks if clocksource is registered
|
|
* @c: pointer to a clocksource
|
|
*
|
|
* Private helper function. Must hold clocksource_lock when called.
|
|
*
|
|
* Returns one if the clocksource is already registered, zero otherwise.
|
|
*/
|
|
static int is_registered_source(struct clocksource *c)
|
|
{
|
|
int len = strlen(c->name);
|
|
struct list_head *tmp;
|
|
|
|
list_for_each(tmp, &clocksource_list) {
|
|
struct clocksource *src;
|
|
|
|
src = list_entry(tmp, struct clocksource, list);
|
|
if (strlen(src->name) == len && !strcmp(src->name, c->name))
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* clocksource_register - Used to install new clocksources
|
|
* @t: clocksource to be registered
|
|
*
|
|
* Returns -EBUSY if registration fails, zero otherwise.
|
|
*/
|
|
int clocksource_register(struct clocksource *c)
|
|
{
|
|
int ret = 0;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&clocksource_lock, flags);
|
|
/* check if clocksource is already registered */
|
|
if (is_registered_source(c)) {
|
|
printk("register_clocksource: Cannot register %s. "
|
|
"Already registered!", c->name);
|
|
ret = -EBUSY;
|
|
} else {
|
|
/* register it */
|
|
list_add(&c->list, &clocksource_list);
|
|
/* scan the registered clocksources, and pick the best one */
|
|
next_clocksource = select_clocksource();
|
|
}
|
|
spin_unlock_irqrestore(&clocksource_lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(clocksource_register);
|
|
|
|
/**
|
|
* clocksource_reselect - Rescan list for next clocksource
|
|
*
|
|
* A quick helper function to be used if a clocksource changes its
|
|
* rating. Forces the clocksource list to be re-scanned for the best
|
|
* clocksource.
|
|
*/
|
|
void clocksource_reselect(void)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&clocksource_lock, flags);
|
|
next_clocksource = select_clocksource();
|
|
spin_unlock_irqrestore(&clocksource_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(clocksource_reselect);
|
|
|
|
#ifdef CONFIG_SYSFS
|
|
/**
|
|
* sysfs_show_current_clocksources - sysfs interface for current clocksource
|
|
* @dev: unused
|
|
* @buf: char buffer to be filled with clocksource list
|
|
*
|
|
* Provides sysfs interface for listing current clocksource.
|
|
*/
|
|
static ssize_t
|
|
sysfs_show_current_clocksources(struct sys_device *dev, char *buf)
|
|
{
|
|
char *curr = buf;
|
|
|
|
spin_lock_irq(&clocksource_lock);
|
|
curr += sprintf(curr, "%s ", curr_clocksource->name);
|
|
spin_unlock_irq(&clocksource_lock);
|
|
|
|
curr += sprintf(curr, "\n");
|
|
|
|
return curr - buf;
|
|
}
|
|
|
|
/**
|
|
* sysfs_override_clocksource - interface for manually overriding clocksource
|
|
* @dev: unused
|
|
* @buf: name of override clocksource
|
|
* @count: length of buffer
|
|
*
|
|
* Takes input from sysfs interface for manually overriding the default
|
|
* clocksource selction.
|
|
*/
|
|
static ssize_t sysfs_override_clocksource(struct sys_device *dev,
|
|
const char *buf, size_t count)
|
|
{
|
|
size_t ret = count;
|
|
/* strings from sysfs write are not 0 terminated! */
|
|
if (count >= sizeof(override_name))
|
|
return -EINVAL;
|
|
|
|
/* strip of \n: */
|
|
if (buf[count-1] == '\n')
|
|
count--;
|
|
if (count < 1)
|
|
return -EINVAL;
|
|
|
|
spin_lock_irq(&clocksource_lock);
|
|
|
|
/* copy the name given: */
|
|
memcpy(override_name, buf, count);
|
|
override_name[count] = 0;
|
|
|
|
/* try to select it: */
|
|
next_clocksource = select_clocksource();
|
|
|
|
spin_unlock_irq(&clocksource_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sysfs_show_available_clocksources - sysfs interface for listing clocksource
|
|
* @dev: unused
|
|
* @buf: char buffer to be filled with clocksource list
|
|
*
|
|
* Provides sysfs interface for listing registered clocksources
|
|
*/
|
|
static ssize_t
|
|
sysfs_show_available_clocksources(struct sys_device *dev, char *buf)
|
|
{
|
|
struct list_head *tmp;
|
|
char *curr = buf;
|
|
|
|
spin_lock_irq(&clocksource_lock);
|
|
list_for_each(tmp, &clocksource_list) {
|
|
struct clocksource *src;
|
|
|
|
src = list_entry(tmp, struct clocksource, list);
|
|
curr += sprintf(curr, "%s ", src->name);
|
|
}
|
|
spin_unlock_irq(&clocksource_lock);
|
|
|
|
curr += sprintf(curr, "\n");
|
|
|
|
return curr - buf;
|
|
}
|
|
|
|
/*
|
|
* Sysfs setup bits:
|
|
*/
|
|
static SYSDEV_ATTR(current_clocksource, 0600, sysfs_show_current_clocksources,
|
|
sysfs_override_clocksource);
|
|
|
|
static SYSDEV_ATTR(available_clocksource, 0600,
|
|
sysfs_show_available_clocksources, NULL);
|
|
|
|
static struct sysdev_class clocksource_sysclass = {
|
|
set_kset_name("clocksource"),
|
|
};
|
|
|
|
static struct sys_device device_clocksource = {
|
|
.id = 0,
|
|
.cls = &clocksource_sysclass,
|
|
};
|
|
|
|
static int __init init_clocksource_sysfs(void)
|
|
{
|
|
int error = sysdev_class_register(&clocksource_sysclass);
|
|
|
|
if (!error)
|
|
error = sysdev_register(&device_clocksource);
|
|
if (!error)
|
|
error = sysdev_create_file(
|
|
&device_clocksource,
|
|
&attr_current_clocksource);
|
|
if (!error)
|
|
error = sysdev_create_file(
|
|
&device_clocksource,
|
|
&attr_available_clocksource);
|
|
return error;
|
|
}
|
|
|
|
device_initcall(init_clocksource_sysfs);
|
|
#endif /* CONFIG_SYSFS */
|
|
|
|
/**
|
|
* boot_override_clocksource - boot clock override
|
|
* @str: override name
|
|
*
|
|
* Takes a clocksource= boot argument and uses it
|
|
* as the clocksource override name.
|
|
*/
|
|
static int __init boot_override_clocksource(char* str)
|
|
{
|
|
unsigned long flags;
|
|
spin_lock_irqsave(&clocksource_lock, flags);
|
|
if (str)
|
|
strlcpy(override_name, str, sizeof(override_name));
|
|
spin_unlock_irqrestore(&clocksource_lock, flags);
|
|
return 1;
|
|
}
|
|
|
|
__setup("clocksource=", boot_override_clocksource);
|
|
|
|
/**
|
|
* boot_override_clock - Compatibility layer for deprecated boot option
|
|
* @str: override name
|
|
*
|
|
* DEPRECATED! Takes a clock= boot argument and uses it
|
|
* as the clocksource override name
|
|
*/
|
|
static int __init boot_override_clock(char* str)
|
|
{
|
|
if (!strcmp(str, "pmtmr")) {
|
|
printk("Warning: clock=pmtmr is deprecated. "
|
|
"Use clocksource=acpi_pm.\n");
|
|
return boot_override_clocksource("acpi_pm");
|
|
}
|
|
printk("Warning! clock= boot option is deprecated. "
|
|
"Use clocksource=xyz\n");
|
|
return boot_override_clocksource(str);
|
|
}
|
|
|
|
__setup("clock=", boot_override_clock);
|