docs/devel/clocks.rst

4 What are clocks?
8 distribution of clocks in QEMU.
26 Here is an example of clocks::
58 represent the clock being inactive or gated. The clocks do not model
62 All clocks contain this state: outputs as well as inputs. This allows
65 clocks in the tree.
67 To ease interaction with clocks, helpers with a unit suffix are defined for
79 Adding clocks to a device must be done during the init method of the Device
98 parameter to initialize the clocks: it has the same behaviour as calling the
101 As an example, the following creates 2 clocks to a device: one input and one
120      * static array describing clocks:
153 nothing else to do. This value will be propagated to other clocks when
154 connecting the clocks together and devices will fetch the right value during
198 Retrieving clocks from a device
214 Connecting two clocks together
217 To connect two clocks together, use the ``clock_set_source()`` function.
218 Given two clocks ``clk1``, and ``clk2``, ``clock_set_source(clk2, clk1);``
234 other clocks.
258 clocks get the new clock period value: *Clock 2*, *Clock 3* and *Clock 4*.
266 By default, when clocks are connected together, the child
267 clocks run with the same period as their source (parent) clock.
275 multiplier to 2 and its divider to 3, the child clocks will run
290 Unconnected input clocks
378 by the tick count, because clocks can have periods which are not a
431 connected clocks and their callbacks, this operation must be done
434 For the same reason, one can update clocks only when it is allowed to have
446 Aliasing clocks
454 ``qdev_alias_clock()`` works for both input and output clocks.
496 clock migration. Alias clocks must not be migrated.