问题描述
在Linux下如何是时钟架构来实现。
有一个文件在include / linux / clkdev.h
In Linux how is the Clock Architecture implemented. There is a file include/linux/clkdev.h
struct clk_lookup {
struct list_head node;
const char *dev_id;
const char *con_id;
struct clk *clk;
};
什么是各个领域，它是在弓/ ARM /板时钟架构广泛使用*** / ... ？
推荐答案
通用Linux时钟基础结构中的。对于ARM，萨沙豪尔创造最近（过去两年）的的公共时钟的框架工作。该时钟在的父/子的关系结构。典型的SOC（片上系统）具有从要么缩小（带计数器）晶体创建主时钟或与一个PLL，也许两者兼而有之。这些层次是节省功耗很重要。通常的设备只使用的最低/最小的树时钟之一。当一个设备请求一个时钟，基础结构，确保所有的家长都开始了。
The generic Linux clock infra-structure is documented in clk.txt. For the ARM, Sasha Hauer created the common clock frame-work recently (last two years). The clocks are structured in a parent/child relation. Typical SOC (system on chip) has main clocks created from a crystal which are either scaled down (with a counter) or up with a PLL and maybe both. They hierarchy is important for power savings. Usually devices are only using one of the lowest/youngest clocks in the tree. When a device requests a clock, the infra-structure ensures that all parents are started.
previously（传统），时钟是从的机文件通过的（参考弓/ ARM /板*** / ）通过平台数据驱动器/设备;最终通过 platform_device_register（）。有时，时钟均/从设备名称派生而来。例如， FEC 的驱动程序可能使用的 FEC-CLK 的。这并没有对多机配置运作良好，因此引入平台数据机制。即使是较新的机器使用的 DT （或设备表）。在这里，没有机文件，只有从引导装载程序传递到内核的设备表。在这种情况下，在 DT 告诉使用哪个时钟驱动。
Previously (legacy), clocks were passed from the machine file (reference arch/arm/Board***/) to the driver/device via platform data; ultimately through platform_device_register(). Sometimes, the clocks were/are derived from the device name. For example the fec driver might use fec-clk. This did not work well for multiple machine configurations, so the platform data mechanism was introduced. Even newer machinery uses a dt (or device table). Here, there are no machine files, only a device table that is passed from the boot loader to the kernel. In this case, the dt tells the driver which clock to use.
本来，的dev_id 和 CON_ID 是要涉及时钟为设备并时钟是的连接（父/子）。通常是的dev_id 或 CON_ID 因为只需要一个方面是NULL。我认为这种观点是发现自己的不足;特别是对于启动整个时钟链。因此，根据Linux版本，答案而变化。即使在电流源，一些平台（如猎户座）仍然使用旧的机制。我不认为猎户座支持的
Originally, the dev_id and con_id were to relate clocks for a device and clocks that are connected (parent/child). Usually either dev_id or con_id are NULL as only one aspect is needed. I think that this view was found wanting; especially for starting an entire clock chain. So, depending on the Linux version, the answer varies. Even in the current source, some platforms (like orion) still use an older mechanism. I don't think orion supports device trees.
具体的答案将取决于你的Linux版本和机器（也可能是平台）
参见：的，的
Specific answers will depend on your Linux version and the machine (and possibly platform) in use.
See also: clkdev.c, clk.c
开源 - 有许多突变。他们都有不同的计划。
参考：ARM的clkdev 罗素国王消息，原来并不意味着排序。
Reference: Russell Kings message on ARM clkdev, original did not imply ordering.
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