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><H1
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><H1
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><A
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><A
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NAME="POWER-INFO">Power Management Information</H1
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NAME="POWER-INFO">Power Management Information</H1
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><DIV
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><DIV
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CLASS="REFNAMEDIV"
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CLASS="REFNAMEDIV"
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><A
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><A
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NAME="AEN15678"
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NAME="AEN15678"
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></A
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></A
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><H2
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><H2
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>Name</H2
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>Name</H2
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>Obtaining Power Management Information -- finding out about the various power controllers in the system</DIV
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>Obtaining Power Management Information -- finding out about the various power controllers in the system</DIV
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><DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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CLASS="REFSYNOPSISDIV"
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><A
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><A
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NAME="AEN15681"><H2
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NAME="AEN15681"><H2
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>Synopsis</H2
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>Synopsis</H2
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><DIV
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><DIV
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CLASS="FUNCSYNOPSIS"
|
CLASS="FUNCSYNOPSIS"
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><A
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><A
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NAME="AEN15682"><P
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NAME="AEN15682"><P
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></P
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></P
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><TABLE
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><TABLE
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BORDER="5"
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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WIDTH="70%"
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><TR
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><TR
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><TD
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><TD
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><PRE
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><PRE
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CLASS="FUNCSYNOPSISINFO"
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CLASS="FUNCSYNOPSISINFO"
|
>#include <cyg/power/power.h>
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>#include <cyg/power/power.h>
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|
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extern PowerController __POWER__[], __POWER_END__;
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extern PowerController __POWER__[], __POWER_END__;
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extern PowerController power_controller_cpu;
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extern PowerController power_controller_cpu;
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extern cyg_handle_t power_thread_handle;</PRE
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extern cyg_handle_t power_thread_handle;</PRE
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></TD
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></TD
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></TR
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></TR
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></TABLE
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></TABLE
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><P
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><P
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><CODE
|
><CODE
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><CODE
|
><CODE
|
CLASS="FUNCDEF"
|
CLASS="FUNCDEF"
|
> PowerMode power_get_mode
|
> PowerMode power_get_mode
|
</CODE
|
</CODE
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>(void);</CODE
|
>(void);</CODE
|
></P
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></P
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><P
|
><P
|
><CODE
|
><CODE
|
><CODE
|
><CODE
|
CLASS="FUNCDEF"
|
CLASS="FUNCDEF"
|
> PowerMode power_get_desired_mode
|
> PowerMode power_get_desired_mode
|
</CODE
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</CODE
|
>(void);</CODE
|
>(void);</CODE
|
></P
|
></P
|
><P
|
><P
|
><CODE
|
><CODE
|
><CODE
|
><CODE
|
CLASS="FUNCDEF"
|
CLASS="FUNCDEF"
|
> PowerMode power_get_controller_mode
|
> PowerMode power_get_controller_mode
|
</CODE
|
</CODE
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>( PowerController* controller
|
>( PowerController* controller
|
);</CODE
|
);</CODE
|
></P
|
></P
|
><P
|
><P
|
><CODE
|
><CODE
|
><CODE
|
><CODE
|
CLASS="FUNCDEF"
|
CLASS="FUNCDEF"
|
> PowerMode power_get_controller_desired_mode
|
> PowerMode power_get_controller_desired_mode
|
</CODE
|
</CODE
|
>( PowerController* controller
|
>( PowerController* controller
|
);</CODE
|
);</CODE
|
></P
|
></P
|
><P
|
><P
|
><CODE
|
><CODE
|
><CODE
|
><CODE
|
CLASS="FUNCDEF"
|
CLASS="FUNCDEF"
|
> const char* power_get_controller_id
|
> const char* power_get_controller_id
|
</CODE
|
</CODE
|
>( PowerController* controller
|
>( PowerController* controller
|
);</CODE
|
);</CODE
|
></P
|
></P
|
><P
|
><P
|
></P
|
></P
|
></DIV
|
></DIV
|
></DIV
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></DIV
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><DIV
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><DIV
|
CLASS="REFSECT1"
|
CLASS="REFSECT1"
|
><A
|
><A
|
NAME="POWER-INFO-ACCESS"
|
NAME="POWER-INFO-ACCESS"
|
></A
|
></A
|
><H2
|
><H2
|
>Accessing Power Controllers</H2
|
>Accessing Power Controllers</H2
|
><P
|
><P
|
>All the power controllers in a system are held in a table, filled in
|
>All the power controllers in a system are held in a table, filled in
|
at link-time. The symbols <TT
|
at link-time. The symbols <TT
|
CLASS="VARNAME"
|
CLASS="VARNAME"
|
>__POWER__</TT
|
>__POWER__</TT
|
> and
|
> and
|
<TT
|
<TT
|
CLASS="VARNAME"
|
CLASS="VARNAME"
|
>__POWER_END</TT
|
>__POWER_END</TT
|
> can be used to iterate through this
|
> can be used to iterate through this
|
table, for example:</P
|
table, for example:</P
|
><TABLE
|
><TABLE
|
BORDER="5"
|
BORDER="5"
|
BGCOLOR="#E0E0F0"
|
BGCOLOR="#E0E0F0"
|
WIDTH="70%"
|
WIDTH="70%"
|
><TR
|
><TR
|
><TD
|
><TD
|
><PRE
|
><PRE
|
CLASS="PROGRAMLISTING"
|
CLASS="PROGRAMLISTING"
|
>PowerController* controller;
|
>PowerController* controller;
|
for (controller = &(__POWER__[0]);
|
for (controller = &(__POWER__[0]);
|
controller != &(__POWER_END__);
|
controller != &(__POWER_END__);
|
controller++) {
|
controller++) {
|
|
|
…
|
…
|
}</PRE
|
}</PRE
|
></TD
|
></TD
|
></TR
|
></TR
|
></TABLE
|
></TABLE
|
><P
|
><P
|
>Each controller has an associated priority, controlling the order in
|
>Each controller has an associated priority, controlling the order in
|
which they appear in the table. Typically a software-only component
|
which they appear in the table. Typically a software-only component
|
such as a TCP/IP stack would use a small number for the priority, so
|
such as a TCP/IP stack would use a small number for the priority, so
|
that it appears near the start of the table, whereas a device driver
|
that it appears near the start of the table, whereas a device driver
|
would be nearer the back of the table. When switching to a
|
would be nearer the back of the table. When switching to a
|
lower-powered mode the power management package will iterate through
|
lower-powered mode the power management package will iterate through
|
this table from front to back, thus ensuring that for example the
|
this table from front to back, thus ensuring that for example the
|
TCP/IP stack gets a chance to shut down before the underlying ethernet
|
TCP/IP stack gets a chance to shut down before the underlying ethernet
|
or other hardware that the stack depends on. Similarly when switching
|
or other hardware that the stack depends on. Similarly when switching
|
to a higher-powered mode the power management package will iterate
|
to a higher-powered mode the power management package will iterate
|
through this table from back to front.</P
|
through this table from back to front.</P
|
><P
|
><P
|
>In most systems there will be one special controller,
|
>In most systems there will be one special controller,
|
<TT
|
<TT
|
CLASS="VARNAME"
|
CLASS="VARNAME"
|
>power_controller_cpu</TT
|
>power_controller_cpu</TT
|
>, which should be provided by
|
>, which should be provided by
|
one of the architectural, variant or platform HAL packages. This
|
one of the architectural, variant or platform HAL packages. This
|
controller will always be the last entry in the table. It is
|
controller will always be the last entry in the table. It is
|
responsible for the final power down operation when switching to
|
responsible for the final power down operation when switching to
|
<SPAN
|
<SPAN
|
CLASS="TYPE"
|
CLASS="TYPE"
|
>off</SPAN
|
>off</SPAN
|
> mode. Other packages such as device drivers may or
|
> mode. Other packages such as device drivers may or
|
may not declare variable identifiers for their power controllers,
|
may not declare variable identifiers for their power controllers,
|
allowing those controllers to be accessed by name as well as by their
|
allowing those controllers to be accessed by name as well as by their
|
entries in the global table.</P
|
entries in the global table.</P
|
></DIV
|
></DIV
|
><DIV
|
><DIV
|
CLASS="REFSECT1"
|
CLASS="REFSECT1"
|
><A
|
><A
|
NAME="POWER-INFO-GLOBAL"
|
NAME="POWER-INFO-GLOBAL"
|
></A
|
></A
|
><H2
|
><H2
|
>Global Power Modes</H2
|
>Global Power Modes</H2
|
><P
|
><P
|
>The function <TT
|
>The function <TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_mode</TT
|
>power_get_mode</TT
|
> can be called at any
|
> can be called at any
|
time to determine the current power mode for the system as a whole.
|
time to determine the current power mode for the system as a whole.
|
The return value will be one of <TT
|
The return value will be one of <TT
|
CLASS="LITERAL"
|
CLASS="LITERAL"
|
>PowerMode_Active</TT
|
>PowerMode_Active</TT
|
>,
|
>,
|
<TT
|
<TT
|
CLASS="LITERAL"
|
CLASS="LITERAL"
|
>PowerMode_Idle</TT
|
>PowerMode_Idle</TT
|
>, <TT
|
>, <TT
|
CLASS="LITERAL"
|
CLASS="LITERAL"
|
>PowerMode_Sleep</TT
|
>PowerMode_Sleep</TT
|
>
|
>
|
or <TT
|
or <TT
|
CLASS="LITERAL"
|
CLASS="LITERAL"
|
>PowerMode_Off</TT
|
>PowerMode_Off</TT
|
>. In normal circumstances it is
|
>. In normal circumstances it is
|
unlikely that <TT
|
unlikely that <TT
|
CLASS="LITERAL"
|
CLASS="LITERAL"
|
>PowerMode_Off</TT
|
>PowerMode_Off</TT
|
> would be returned since
|
> would be returned since
|
that mode generally means that the cpu is no longer running.</P
|
that mode generally means that the cpu is no longer running.</P
|
><P
|
><P
|
>The function <TT
|
>The function <TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_desired_mode</TT
|
>power_get_desired_mode</TT
|
> returns the
|
> returns the
|
power mode that the system should be running at. Most of the time this
|
power mode that the system should be running at. Most of the time this
|
will be the same value as returned by
|
will be the same value as returned by
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_mode</TT
|
>power_get_mode</TT
|
>. However a different value may be
|
>. However a different value may be
|
returned when in the middle of changing power modes. For example, if
|
returned when in the middle of changing power modes. For example, if
|
the current thread runs at a higher priority than the power management
|
the current thread runs at a higher priority than the power management
|
thread then the latter may have been pre-empted in the middle of a
|
thread then the latter may have been pre-empted in the middle of a
|
mode change: <TT
|
mode change: <TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_mode</TT
|
>power_get_mode</TT
|
> will return the mode
|
> will return the mode
|
the system was running at before the mode change started, and
|
the system was running at before the mode change started, and
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_desired_mode</TT
|
>power_get_desired_mode</TT
|
> will return the mode the
|
> will return the mode the
|
system should end up in when the mode change completes, barring
|
system should end up in when the mode change completes, barring
|
further calls to <TT
|
further calls to <TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_set_mode</TT
|
>power_set_mode</TT
|
>.</P
|
>.</P
|
></DIV
|
></DIV
|
><DIV
|
><DIV
|
CLASS="REFSECT1"
|
CLASS="REFSECT1"
|
><A
|
><A
|
NAME="POWER-INFO-INDIVIDUAL"
|
NAME="POWER-INFO-INDIVIDUAL"
|
></A
|
></A
|
><H2
|
><H2
|
>Individual Controller Power Modes</H2
|
>Individual Controller Power Modes</H2
|
><P
|
><P
|
>The power management package keeps track of the current and desired
|
>The power management package keeps track of the current and desired
|
modes for each power controller, as well as the modes for the system as
|
modes for each power controller, as well as the modes for the system as
|
a whole. The function <TT
|
a whole. The function <TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_controller_mode</TT
|
>power_get_controller_mode</TT
|
>
|
>
|
takes a single argument, a pointer to a power controller, and returns
|
takes a single argument, a pointer to a power controller, and returns
|
the power mode that controller is currently running at. Similarly
|
the power mode that controller is currently running at. Similarly
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_controller_desired_mode</TT
|
>power_get_controller_desired_mode</TT
|
> returns the
|
> returns the
|
power mode that controller should be running at. Most of the time the
|
power mode that controller should be running at. Most of the time the
|
current and desired modes for a given controller will be the same, and
|
current and desired modes for a given controller will be the same, and
|
will also be the same as the global power mode. However if the power
|
will also be the same as the global power mode. However if the power
|
management thread is preeempted in the middle of a mode change then
|
management thread is preeempted in the middle of a mode change then
|
some of the controllers will have been updated to the desired global
|
some of the controllers will have been updated to the desired global
|
mode, whereas others will still be at the old mode. The power
|
mode, whereas others will still be at the old mode. The power
|
management package also provides functionality for manipulating
|
management package also provides functionality for manipulating
|
<A
|
<A
|
HREF="power-change.html#POWER-CHANGE-CONTROLLER"
|
HREF="power-change.html#POWER-CHANGE-CONTROLLER"
|
>individual controllers</A
|
>individual controllers</A
|
>, and for <A
|
>, and for <A
|
HREF="power-attached.html"
|
HREF="power-attached.html"
|
>detaching</A
|
>detaching</A
|
> controllers from
|
> controllers from
|
global mode changes.</P
|
global mode changes.</P
|
></DIV
|
></DIV
|
><DIV
|
><DIV
|
CLASS="REFSECT1"
|
CLASS="REFSECT1"
|
><A
|
><A
|
NAME="POWER-INFO-IDS"
|
NAME="POWER-INFO-IDS"
|
></A
|
></A
|
><H2
|
><H2
|
>Power Controller Identification</H2
|
>Power Controller Identification</H2
|
><P
|
><P
|
>In some scenarios the power management package will run completely
|
>In some scenarios the power management package will run completely
|
automated, and there is no need to identify individual power
|
automated, and there is no need to identify individual power
|
controllers. Any form of identification such as a string
|
controllers. Any form of identification such as a string
|
description would serve no purpose, but would still consume memory in
|
description would serve no purpose, but would still consume memory in
|
the final system. In other scenarios it may be very desirable to
|
the final system. In other scenarios it may be very desirable to
|
provide some means of identification. For example, while still
|
provide some means of identification. For example, while still
|
debugging it may be useful to see a simple string when printing the
|
debugging it may be useful to see a simple string when printing the
|
contents of a power controller structure. Alternatively, if the
|
contents of a power controller structure. Alternatively, if the
|
application is expected to provide some sort of user interface that
|
application is expected to provide some sort of user interface that
|
gives control over which parts of the system are enabled or disabled,
|
gives control over which parts of the system are enabled or disabled,
|
a string identifier for each controller would be useful. To cope with
|
a string identifier for each controller would be useful. To cope with
|
these scenarios the power management package provides a configuration
|
these scenarios the power management package provides a configuration
|
option <TT
|
option <TT
|
CLASS="VARNAME"
|
CLASS="VARNAME"
|
>CYGIMP_POWER_PROVIDE_STRINGS</TT
|
>CYGIMP_POWER_PROVIDE_STRINGS</TT
|
>. When enabled,
|
>. When enabled,
|
each power controller will contain a pointer to a constant string
|
each power controller will contain a pointer to a constant string
|
which can be accessed via a function
|
which can be accessed via a function
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>power_get_controller_id</TT
|
>power_get_controller_id</TT
|
>. When disabled the system
|
>. When disabled the system
|
will not contain these strings, and the function will not be provided.
|
will not contain these strings, and the function will not be provided.
|
The following code illustrates how to use this function.</P
|
The following code illustrates how to use this function.</P
|
><TABLE
|
><TABLE
|
BORDER="5"
|
BORDER="5"
|
BGCOLOR="#E0E0F0"
|
BGCOLOR="#E0E0F0"
|
WIDTH="70%"
|
WIDTH="70%"
|
><TR
|
><TR
|
><TD
|
><TD
|
><PRE
|
><PRE
|
CLASS="PROGRAMLISTING"
|
CLASS="PROGRAMLISTING"
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>#include <stdio.h>
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>#include <stdio.h>
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#include <pkgconf/system.h>
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#include <pkgconf/system.h>
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#ifndef CYGPKG_POWER
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#ifndef CYGPKG_POWER
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# error The power management package is not present.
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# error The power management package is not present.
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#endif
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#endif
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#include <pkgconf/power.h>
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#include <pkgconf/power.h>
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#ifndef CYGIMP_POWER_PROVIDE_STRINGS
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#ifndef CYGIMP_POWER_PROVIDE_STRINGS
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# error Power controller identifiers are not available.
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# error Power controller identifiers are not available.
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#endif
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#endif
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#include <cyg/power/power.h>
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#include <cyg/power/power.h>
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|
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static const char*
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static const char*
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mode_to_string(PowerMode mode)
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mode_to_string(PowerMode mode)
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{
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{
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const char* result;
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const char* result;
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switch(mode) {
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switch(mode) {
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case PowerMode_Active : result = "active"; break;
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case PowerMode_Active : result = "active"; break;
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case PowerMode_Idle : result = "idle"; break;
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case PowerMode_Idle : result = "idle"; break;
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case PowerMode_Sleep : result = "sleep"; break;
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case PowerMode_Sleep : result = "sleep"; break;
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case PowerMode_Off : result = "off"; break;
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case PowerMode_Off : result = "off"; break;
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default : result = "<unknown>"; break;
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default : result = "<unknown>"; break;
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}
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}
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return result;
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return result;
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}
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}
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|
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int
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int
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main(int argc, char** argv)
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main(int argc, char** argv)
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{
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{
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PowerController* controller;
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PowerController* controller;
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|
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for (controller = &(__POWER__[0]);
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for (controller = &(__POWER__[0]);
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controller != &(__POWER_END__);
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controller != &(__POWER_END__);
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controller++) {
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controller++) {
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printf("Controller @ %p: %s, %s\n", controller,
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printf("Controller @ %p: %s, %s\n", controller,
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power_get_controller_id(controller),
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power_get_controller_id(controller),
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mode_to_string(power_get_controller_mode(controller)));
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mode_to_string(power_get_controller_mode(controller)));
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}
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}
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return 0;
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return 0;
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}</PRE
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}</PRE
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></TD
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></TD
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></TR
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></TR
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></TABLE
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></TABLE
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></DIV
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></DIV
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><DIV
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><DIV
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CLASS="REFSECT1"
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CLASS="REFSECT1"
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><A
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><A
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NAME="POWER-INFO-THREAD"
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NAME="POWER-INFO-THREAD"
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></A
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></A
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><H2
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><H2
|
>The Power Management Thread</H2
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>The Power Management Thread</H2
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><P
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><P
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>If the power management package is configured to use a separate thread
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>If the power management package is configured to use a separate thread
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then a handle for that thread is made available to higher-level code
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then a handle for that thread is made available to higher-level code
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via the variable <TT
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via the variable <TT
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CLASS="VARNAME"
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CLASS="VARNAME"
|
>power_thread_handle</TT
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>power_thread_handle</TT
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>. This handle
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>. This handle
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can be used for a variety of purposes, including manipulating that
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can be used for a variety of purposes, including manipulating that
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thread's priority.</P
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thread's priority.</P
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></DIV
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></DIV
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><DIV
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><DIV
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CLASS="NAVFOOTER"
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CLASS="NAVFOOTER"
|
><HR
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><HR
|
ALIGN="LEFT"
|
ALIGN="LEFT"
|
WIDTH="100%"><TABLE
|
WIDTH="100%"><TABLE
|
SUMMARY="Footer navigation table"
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SUMMARY="Footer navigation table"
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WIDTH="100%"
|
WIDTH="100%"
|
BORDER="0"
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BORDER="0"
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CELLPADDING="0"
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CELLPADDING="0"
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CELLSPACING="0"
|
CELLSPACING="0"
|
><TR
|
><TR
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="left"
|
ALIGN="left"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="power-intro.html"
|
HREF="power-intro.html"
|
ACCESSKEY="P"
|
ACCESSKEY="P"
|
>Prev</A
|
>Prev</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="34%"
|
WIDTH="34%"
|
ALIGN="center"
|
ALIGN="center"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="ecos-ref.html"
|
HREF="ecos-ref.html"
|
ACCESSKEY="H"
|
ACCESSKEY="H"
|
>Home</A
|
>Home</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="right"
|
ALIGN="right"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="power-change.html"
|
HREF="power-change.html"
|
ACCESSKEY="N"
|
ACCESSKEY="N"
|
>Next</A
|
>Next</A
|
></TD
|
></TD
|
></TR
|
></TR
|
><TR
|
><TR
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="left"
|
ALIGN="left"
|
VALIGN="top"
|
VALIGN="top"
|
>Introduction</TD
|
>Introduction</TD
|
><TD
|
><TD
|
WIDTH="34%"
|
WIDTH="34%"
|
ALIGN="center"
|
ALIGN="center"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="services-power.html"
|
HREF="services-power.html"
|
ACCESSKEY="U"
|
ACCESSKEY="U"
|
>Up</A
|
>Up</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="right"
|
ALIGN="right"
|
VALIGN="top"
|
VALIGN="top"
|
>Changing Power Modes</TD
|
>Changing Power Modes</TD
|
></TR
|
></TR
|
></TABLE
|
></TABLE
|
></DIV
|
></DIV
|
></BODY
|
></BODY
|
></HTML
|
></HTML
|
|
|
