From b05a76580f0110c26ca9c482e1444715c52c9c4f Mon Sep 17 00:00:00 2001 From: xiabin Date: Sun, 28 Oct 2018 10:14:38 +0800 Subject: [PATCH] fix typo of "closk" --- Timers/linux-timers-5.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Timers/linux-timers-5.md b/Timers/linux-timers-5.md index 861e07d..ebee492 100644 --- a/Timers/linux-timers-5.md +++ b/Timers/linux-timers-5.md @@ -10,7 +10,7 @@ At first let's refresh your memory and try to remember what is it `clocksource` > For example issuing the command 'date' on a Linux system will eventually read the clock source to determine exactly what time it is. -The Linux kernel supports many different clock sources. You can find some of them in the [drivers/closksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource). For example old good [Intel 8253](https://en.wikipedia.org/wiki/Intel_8253) - [programmable interval timer](https://en.wikipedia.org/wiki/Programmable_interval_timer) with `1193182` Hz frequency, yet another one - [ACPI PM](http://uefi.org/sites/default/files/resources/ACPI_5.pdf) timer with `3579545` Hz frequency. Besides the [drivers/closksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource) directory, each architecture may provide own architecture-specific clock sources. For example [x86](https://en.wikipedia.org/wiki/X86) architecture provides [High Precision Event Timer](https://en.wikipedia.org/wiki/High_Precision_Event_Timer), or for example [powerpc](https://en.wikipedia.org/wiki/PowerPC) provides access to the processor timer through `timebase` register. +The Linux kernel supports many different clock sources. You can find some of them in the [drivers/clocksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource). For example old good [Intel 8253](https://en.wikipedia.org/wiki/Intel_8253) - [programmable interval timer](https://en.wikipedia.org/wiki/Programmable_interval_timer) with `1193182` Hz frequency, yet another one - [ACPI PM](http://uefi.org/sites/default/files/resources/ACPI_5.pdf) timer with `3579545` Hz frequency. Besides the [drivers/clocksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource) directory, each architecture may provide own architecture-specific clock sources. For example [x86](https://en.wikipedia.org/wiki/X86) architecture provides [High Precision Event Timer](https://en.wikipedia.org/wiki/High_Precision_Event_Timer), or for example [powerpc](https://en.wikipedia.org/wiki/PowerPC) provides access to the processor timer through `timebase` register. Each clock source provides monotonic atomic counter. As I already wrote, the Linux kernel supports a huge set of different clock source and each clock source has own parameters like [frequency](https://en.wikipedia.org/wiki/Frequency). The main goal of the `clocksource` framework is to provide [API](https://en.wikipedia.org/wiki/Application_programming_interface) to select best available clock source in the system i.e. a clock source with the highest frequency. Additional goal of the `clocksource` framework is to represent an atomic counter provided by a clock source in human units. In this time, nanoseconds are the favorite choice for the time value units of the given clock source in the Linux kernel. @@ -89,7 +89,7 @@ This function defined in the [kernel/time/clockevents.c](https://github.com/torv * address of a `clock_event_device` structure which represents a clock event device. -So, to register a clock event device, at first we need to initialize `clock_event_device` structure with parameters of a certain clock event device. Let's take a look at one random clock event device in the Linux kernel source code. We can find one in the [drivers/closksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource) directory or try to take a look at an architecture-specific clock event device. Let's take for example - [Periodic Interval Timer (PIT) for at91sam926x](http://www.atmel.com/Images/doc6062.pdf). You can find its implementation in the [drivers/closksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource/timer-atmel-pit.c). +So, to register a clock event device, at first we need to initialize `clock_event_device` structure with parameters of a certain clock event device. Let's take a look at one random clock event device in the Linux kernel source code. We can find one in the [drivers/clocksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource) directory or try to take a look at an architecture-specific clock event device. Let's take for example - [Periodic Interval Timer (PIT) for at91sam926x](http://www.atmel.com/Images/doc6062.pdf). You can find its implementation in the [drivers/clocksource](https://github.com/torvalds/linux/tree/master/drivers/clocksource/timer-atmel-pit.c). First of all let's look at initialization of the `clock_event_device` structure. This occurs in the `at91sam926x_pit_common_init` function: