UACPI: Difference between revisions

Below is an example of basic uACPI initialization sequence that enters ACPI mode, parses tables, brings the event system online, and finally loads & initializes the namespace.

 

#include <uacpi/uacpi.h>

#include <uacpi/event.h>

return 0;

}

 

== Code examples ==

so that it's called by kernel code during initialization.

 

// ps2k.c

#include <uacpi/utilities.h>

uacpi_find_devices(PS2K_PNP_ID, match_ps2k, NULL);

}

 

// acpi_init.c

void find_acpi_devices(void) {

// ...and more

}

 

As you can see it's a very simple approach, but it has lots of drawbacks:

In this approach, we treat the ACPI namespace as a bus in our kernel, and let devices provide a way to identify them.

 

// acpi_bus.h

#include <uacpi/uacpi.h>

 

void acpi_register_driver(struct acpi_driver *driver);

 

// ps2k.c

#include <acpi_bus.h>

return 0;

}

 

// acpi_bus.c

#include <acpi_bus.h>

);

}

 

As you can see above, this approach is more scalable, faster, and involves way less code duplication.

 

=== Shutting Down the System ===

#include <uacpi/sleep.h>

 

return 0;

}

 

=== Hooking Up the Power Button ===

The example below hooks up the power button press using a fixed event callback.

 

#include <uacpi/event.h>

 

return 0;

}

 

Note that some of the more modern hardware routes the power button in a more complicated way, via an embedded controller.