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author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-13 09:54:35 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-13 09:54:45 -0700 |
commit | e7f2f9918c0e97aa98ba147ca387e2c7238f0711 (patch) | |
tree | dd85d6d2907bffeda76b42ce55a445e3142fe738 /Documentation | |
parent | 11a96d1820113fde0d55c3487b7da7a9031326b8 (diff) | |
parent | c00193f9f09f9b852249a66391985f585d066084 (diff) | |
download | kernel_samsung_tuna-e7f2f9918c0e97aa98ba147ca387e2c7238f0711.zip kernel_samsung_tuna-e7f2f9918c0e97aa98ba147ca387e2c7238f0711.tar.gz kernel_samsung_tuna-e7f2f9918c0e97aa98ba147ca387e2c7238f0711.tar.bz2 |
Merge phase #5 (misc) of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
Merges oprofile, timers/hpet, x86/traps, x86/time, and x86/core misc items.
* 'x86-core-v4-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (132 commits)
x86: change early_ioremap to use slots instead of nesting
x86: adjust dependencies for CONFIG_X86_CMOV
dumpstack: x86: various small unification steps, fix
x86: remove additional_cpus
x86: remove additional_cpus configurability
x86: improve UP kernel when CPU-hotplug and SMP is enabled
dumpstack: x86: various small unification steps
dumpstack: i386: make kstack= an early boot-param and add oops=panic
dumpstack: x86: use log_lvl and unify trace formatting
dumptrace: x86: consistently include loglevel, print stack switch
dumpstack: x86: add "end" parameter to valid_stack_ptr and print_context_stack
dumpstack: x86: make printk_address equal
dumpstack: x86: move die_nmi to dumpstack_32.c
traps: x86: finalize unification of traps.c
traps: x86: make traps_32.c and traps_64.c equal
traps: x86: various noop-changes preparing for unification of traps_xx.c
traps: x86_64: use task_pid_nr(tsk) instead of tsk->pid in do_general_protection
traps: i386: expand clear_mem_error and remove from mach_traps.h
traps: x86_64: make io_check_error equal to the one on i386
traps: i386: use preempt_conditional_sti/cli in do_int3
...
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/00-INDEX | 2 | ||||
-rw-r--r-- | Documentation/timers/00-INDEX | 10 | ||||
-rw-r--r-- | Documentation/timers/hpet.txt (renamed from Documentation/hpet.txt) | 43 |
3 files changed, 31 insertions, 24 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index 7306081..4382778 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -159,8 +159,6 @@ hayes-esp.txt - info on using the Hayes ESP serial driver. highuid.txt - notes on the change from 16 bit to 32 bit user/group IDs. -hpet.txt - - High Precision Event Timer Driver for Linux. timers/ - info on the timer related topics hw_random.txt diff --git a/Documentation/timers/00-INDEX b/Documentation/timers/00-INDEX new file mode 100644 index 0000000..397dc35 --- /dev/null +++ b/Documentation/timers/00-INDEX @@ -0,0 +1,10 @@ +00-INDEX + - this file +highres.txt + - High resolution timers and dynamic ticks design notes +hpet.txt + - High Precision Event Timer Driver for Linux +hrtimers.txt + - subsystem for high-resolution kernel timers +timer_stats.txt + - timer usage statistics diff --git a/Documentation/hpet.txt b/Documentation/timers/hpet.txt index 6ad52d9..e7c09ab 100644 --- a/Documentation/hpet.txt +++ b/Documentation/timers/hpet.txt @@ -1,21 +1,32 @@ High Precision Event Timer Driver for Linux -The High Precision Event Timer (HPET) hardware is the future replacement -for the 8254 and Real Time Clock (RTC) periodic timer functionality. -Each HPET can have up to 32 timers. It is possible to configure the -first two timers as legacy replacements for 8254 and RTC periodic timers. -A specification done by Intel and Microsoft can be found at -<http://www.intel.com/technology/architecture/hpetspec.htm>. +The High Precision Event Timer (HPET) hardware follows a specification +by Intel and Microsoft which can be found at + + http://www.intel.com/technology/architecture/hpetspec.htm + +Each HPET has one fixed-rate counter (at 10+ MHz, hence "High Precision") +and up to 32 comparators. Normally three or more comparators are provided, +each of which can generate oneshot interupts and at least one of which has +additional hardware to support periodic interrupts. The comparators are +also called "timers", which can be misleading since usually timers are +independent of each other ... these share a counter, complicating resets. + +HPET devices can support two interrupt routing modes. In one mode, the +comparators are additional interrupt sources with no particular system +role. Many x86 BIOS writers don't route HPET interrupts at all, which +prevents use of that mode. They support the other "legacy replacement" +mode where the first two comparators block interrupts from 8254 timers +and from the RTC. The driver supports detection of HPET driver allocation and initialization of the HPET before the driver module_init routine is called. This enables platform code which uses timer 0 or 1 as the main timer to intercept HPET initialization. An example of this initialization can be found in -arch/i386/kernel/time_hpet.c. +arch/x86/kernel/hpet.c. -The driver provides two APIs which are very similar to the API found in -the rtc.c driver. There is a user space API and a kernel space API. -An example user space program is provided below. +The driver provides a userspace API which resembles the API found in the +RTC driver framework. An example user space program is provided below. #include <stdio.h> #include <stdlib.h> @@ -286,15 +297,3 @@ out: return; } - -The kernel API has three interfaces exported from the driver: - - hpet_register(struct hpet_task *tp, int periodic) - hpet_unregister(struct hpet_task *tp) - hpet_control(struct hpet_task *tp, unsigned int cmd, unsigned long arg) - -The kernel module using this interface fills in the ht_func and ht_data -members of the hpet_task structure before calling hpet_register. -hpet_control simply vectors to the hpet_ioctl routine and has the same -commands and respective arguments as the user API. hpet_unregister -is used to terminate usage of the HPET timer reserved by hpet_register. |