diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 14 | ||||
| -rw-r--r-- | include/linux/clocksource.h | 181 | ||||
| -rw-r--r-- | kernel/time/Makefile | 1 | ||||
| -rw-r--r-- | kernel/time/clocksource.c | 344 | ||||
| -rw-r--r-- | kernel/time/jiffies.c | 73 |
5 files changed, 609 insertions, 4 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index bca6f389da66..968631678d4a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -61,6 +61,7 @@ parameter is applicable: MTD MTD support is enabled. NET Appropriate network support is enabled. NUMA NUMA support is enabled. + GENERIC_TIME The generic timeofday code is enabled. NFS Appropriate NFS support is enabled. OSS OSS sound support is enabled. PARIDE The ParIDE subsystem is enabled. @@ -341,10 +342,11 @@ running once the system is up. Value can be changed at runtime via /selinux/checkreqprot. - clock= [BUGS=IA-32,HW] gettimeofday timesource override. - Forces specified timesource (if avaliable) to be used - when calculating gettimeofday(). If specicified - timesource is not avalible, it defaults to PIT. + clock= [BUGS=IA-32, HW] gettimeofday clocksource override. + [Deprecated] + Forces specified clocksource (if avaliable) to be used + when calculating gettimeofday(). If specified + clocksource is not avalible, it defaults to PIT. Format: { pit | tsc | cyclone | pmtmr } disable_8254_timer @@ -1617,6 +1619,10 @@ running once the system is up. time Show timing data prefixed to each printk message line + clocksource= [GENERIC_TIME] Override the default clocksource + Override the default clocksource and use the clocksource + with the name specified. + tipar.timeout= [HW,PPT] Set communications timeout in tenths of a second (default 15). diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h new file mode 100644 index 000000000000..c4187cda0ee4 --- /dev/null +++ b/include/linux/clocksource.h @@ -0,0 +1,181 @@ +/* linux/include/linux/clocksource.h + * + * This file contains the structure definitions for clocksources. + * + * If you are not a clocksource, or timekeeping code, you should + * not be including this file! + */ +#ifndef _LINUX_CLOCKSOURCE_H +#define _LINUX_CLOCKSOURCE_H + +#include <linux/types.h> +#include <linux/timex.h> +#include <linux/time.h> +#include <linux/list.h> +#include <asm/div64.h> +#include <asm/io.h> + +/* clocksource cycle base type */ +typedef u64 cycle_t; + +/** + * struct clocksource - hardware abstraction for a free running counter + * Provides mostly state-free accessors to the underlying hardware. + * + * @name: ptr to clocksource name + * @list: list head for registration + * @rating: rating value for selection (higher is better) + * To avoid rating inflation the following + * list should give you a guide as to how + * to assign your clocksource a rating + * 1-99: Unfit for real use + * Only available for bootup and testing purposes. + * 100-199: Base level usability. + * Functional for real use, but not desired. + * 200-299: Good. + * A correct and usable clocksource. + * 300-399: Desired. + * A reasonably fast and accurate clocksource. + * 400-499: Perfect + * The ideal clocksource. A must-use where + * available. + * @read: returns a cycle value + * @mask: bitmask for two's complement + * subtraction of non 64 bit counters + * @mult: cycle to nanosecond multiplier + * @shift: cycle to nanosecond divisor (power of two) + * @update_callback: called when safe to alter clocksource values + * @is_continuous: defines if clocksource is free-running. + * @interval_cycles: Used internally by timekeeping core, please ignore. + * @interval_snsecs: Used internally by timekeeping core, please ignore. + */ +struct clocksource { + char *name; + struct list_head list; + int rating; + cycle_t (*read)(void); + cycle_t mask; + u32 mult; + u32 shift; + int (*update_callback)(void); + int is_continuous; + + /* timekeeping specific data, ignore */ + cycle_t interval_cycles; + u64 interval_snsecs; +}; + + +/** + * clocksource_khz2mult - calculates mult from khz and shift + * @khz: Clocksource frequency in KHz + * @shift_constant: Clocksource shift factor + * + * Helper functions that converts a khz counter frequency to a timsource + * multiplier, given the clocksource shift value + */ +static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) +{ + /* khz = cyc/(Million ns) + * mult/2^shift = ns/cyc + * mult = ns/cyc * 2^shift + * mult = 1Million/khz * 2^shift + * mult = 1000000 * 2^shift / khz + * mult = (1000000<<shift) / khz + */ + u64 tmp = ((u64)1000000) << shift_constant; + + tmp += khz/2; /* round for do_div */ + do_div(tmp, khz); + + return (u32)tmp; +} + +/** + * clocksource_hz2mult - calculates mult from hz and shift + * @hz: Clocksource frequency in Hz + * @shift_constant: Clocksource shift factor + * + * Helper functions that converts a hz counter + * frequency to a timsource multiplier, given the + * clocksource shift value + */ +static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) +{ + /* hz = cyc/(Billion ns) + * mult/2^shift = ns/cyc + * mult = ns/cyc * 2^shift + * mult = 1Billion/hz * 2^shift + * mult = 1000000000 * 2^shift / hz + * mult = (1000000000<<shift) / hz + */ + u64 tmp = ((u64)1000000000) << shift_constant; + + tmp += hz/2; /* round for do_div */ + do_div(tmp, hz); + + return (u32)tmp; +} + +/** + * read_clocksource: - Access the clocksource's current cycle value + * @cs: pointer to clocksource being read + * + * Uses the clocksource to return the current cycle_t value + */ +static inline cycle_t read_clocksource(struct clocksource *cs) +{ + return cs->read(); +} + +/** + * cyc2ns - converts clocksource cycles to nanoseconds + * @cs: Pointer to clocksource + * @cycles: Cycles + * + * Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds. + * + * XXX - This could use some mult_lxl_ll() asm optimization + */ +static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles) +{ + u64 ret = (u64)cycles; + ret = (ret * cs->mult) >> cs->shift; + return ret; +} + +/** + * calculate_clocksource_interval - Calculates a clocksource interval struct + * + * @c: Pointer to clocksource. + * @length_nsec: Desired interval length in nanoseconds. + * + * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment + * pair and interval request. + * + * Unless you're the timekeeping code, you should not be using this! + */ +static inline void calculate_clocksource_interval(struct clocksource *c, + unsigned long length_nsec) +{ + u64 tmp; + + /* XXX - All of this could use a whole lot of optimization */ + tmp = length_nsec; + tmp <<= c->shift; + tmp += c->mult/2; + do_div(tmp, c->mult); + + c->interval_cycles = (cycle_t)tmp; + if(c->interval_cycles == 0) + c->interval_cycles = 1; + + c->interval_snsecs = (u64)c->interval_cycles * c->mult; +} + +/* used to install a new clocksource */ +int register_clocksource(struct clocksource*); +void reselect_clocksource(void); +struct clocksource* get_next_clocksource(void); + +#endif /* _LINUX_CLOCKSOURCE_H */ diff --git a/kernel/time/Makefile b/kernel/time/Makefile new file mode 100644 index 000000000000..e1dfd8e86cce --- /dev/null +++ b/kernel/time/Makefile @@ -0,0 +1 @@ +obj-y += clocksource.o jiffies.o diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c new file mode 100644 index 000000000000..95dd2200a109 --- /dev/null +++ b/kernel/time/clocksource.c @@ -0,0 +1,344 @@ +/* + * 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> + +/* 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 clocksource_done_booting(void) +{ + finished_booting = 1; + return 0; +} + +late_initcall(clocksource_done_booting); + +/** + * get_next_clocksource - Returns the selected clocksource + * + */ +struct clocksource *get_next_clocksource(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; +} + +/** + * register_clocksource - Used to install new clocksources + * @t: clocksource to be registered + * + * Returns -EBUSY if registration fails, zero otherwise. + */ +int register_clocksource(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(register_clocksource); + +/** + * reselect_clocksource - 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-scaned for the best + * clocksource. + */ +void reselect_clocksource(void) +{ + unsigned long flags; + + spin_lock_irqsave(&clocksource_lock, flags); + next_clocksource = select_clocksource(); + spin_unlock_irqrestore(&clocksource_lock, flags); +} + +/** + * 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_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); + +/** + * 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) +{ + printk("Warning! clock= boot option is deprecated.\n"); + + return boot_override_clocksource(str); +} + +__setup("clock=", boot_override_clock); diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c new file mode 100644 index 000000000000..1fe8376e717b --- /dev/null +++ b/kernel/time/jiffies.c @@ -0,0 +1,73 @@ +/*********************************************************************** +* linux/kernel/time/jiffies.c +* +* This file contains the jiffies based clocksource. +* +* 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. +* +************************************************************************/ +#include <linux/clocksource.h> +#include <linux/jiffies.h> +#include <linux/init.h> + +/* The Jiffies based clocksource is the lowest common + * denominator clock source which should function on + * all systems. It has the same coarse resolution as + * the timer interrupt frequency HZ and it suffers + * inaccuracies caused by missed or lost timer + * interrupts and the inability for the timer + * interrupt hardware to accuratly tick at the + * requested HZ value. It is also not reccomended + * for "tick-less" systems. + */ +#define NSEC_PER_JIFFY ((u32)((((u64)NSEC_PER_SEC)<<8)/ACTHZ)) + +/* Since jiffies uses a simple NSEC_PER_JIFFY multiplier + * conversion, the .shift value could be zero. However + * this would make NTP adjustments impossible as they are + * in units of 1/2^.shift. Thus we use JIFFIES_SHIFT to + * shift both the nominator and denominator the same + * amount, and give ntp adjustments in units of 1/2^8 + * + * The value 8 is somewhat carefully chosen, as anything + * larger can result in overflows. NSEC_PER_JIFFY grows as + * HZ shrinks, so values greater then 8 overflow 32bits when + * HZ=100. + */ +#define JIFFIES_SHIFT 8 + +static cycle_t jiffies_read(void) +{ + return (cycle_t) jiffies; +} + +struct clocksource clocksource_jiffies = { + .name = "jiffies", + .rating = 0, /* lowest rating*/ + .read = jiffies_read, + .mask = 0xffffffff, /*32bits*/ + .mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */ + .shift = JIFFIES_SHIFT, + .is_continuous = 0, /* tick based, not free running */ +}; + +static int __init init_jiffies_clocksource(void) +{ + return register_clocksource(&clocksource_jiffies); +} + +module_init(init_jiffies_clocksource); |