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TTY:console: update document console.txt
Update Documentatin/console/console.txt to reflect the following changes: take_over_console|register_con_driver|unregister_con_driver|bind_con_driver had gone, they had been replace by the new caller hold console lock version, do_take_over_console|do_register_con_driver|do_unregister_con_driver|do_bind_con_driver. This patch also fix a place include wrong description about give_up_console. Signed-off-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -12,20 +12,20 @@ The second type has to be explicitly loaded and unloaded. This will be called
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any time with each driver sharing the console with other drivers including
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the system driver. However, modular drivers cannot take over the console
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that is currently occupied by another modular driver. (Exception: Drivers that
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call take_over_console() will succeed in the takeover regardless of the type
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call do_take_over_console() will succeed in the takeover regardless of the type
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of driver occupying the consoles.) They can only take over the console that is
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occupied by the system driver. In the same token, if the modular driver is
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released by the console, the system driver will take over.
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Modular drivers, from the programmer's point of view, has to call:
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take_over_console() - load and bind driver to console layer
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give_up_console() - unbind and unload driver
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do_take_over_console() - load and bind driver to console layer
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give_up_console() - unload driver, it will only work if driver is fully unbond
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In newer kernels, the following are also available:
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register_con_driver()
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unregister_con_driver()
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do_register_con_driver()
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do_unregister_con_driver()
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If sysfs is enabled, the contents of /sys/class/vtconsole can be
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examined. This shows the console backends currently registered by the
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@ -94,12 +94,12 @@ for more details).
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Notes for developers:
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=====================
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take_over_console() is now broken up into:
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do_take_over_console() is now broken up into:
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register_con_driver()
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bind_con_driver() - private function
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do_register_con_driver()
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do_bind_con_driver() - private function
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give_up_console() is a wrapper to unregister_con_driver(), and a driver must
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give_up_console() is a wrapper to do_unregister_con_driver(), and a driver must
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be fully unbound for this call to succeed. con_is_bound() will check if the
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driver is bound or not.
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@ -109,10 +109,10 @@ Guidelines for console driver writers:
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In order for binding to and unbinding from the console to properly work,
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console drivers must follow these guidelines:
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1. All drivers, except system drivers, must call either register_con_driver()
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or take_over_console(). register_con_driver() will just add the driver to
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1. All drivers, except system drivers, must call either do_register_con_driver()
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or do_take_over_console(). do_register_con_driver() will just add the driver to
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the console's internal list. It won't take over the
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console. take_over_console(), as it name implies, will also take over (or
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console. do_take_over_console(), as it name implies, will also take over (or
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bind to) the console.
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2. All resources allocated during con->con_init() must be released in
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@ -128,10 +128,10 @@ console drivers must follow these guidelines:
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rebind the driver to the console arrives.
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4. Upon exit of the driver, ensure that the driver is totally unbound. If the
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condition is satisfied, then the driver must call unregister_con_driver()
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condition is satisfied, then the driver must call do_unregister_con_driver()
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or give_up_console().
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5. unregister_con_driver() can also be called on conditions which make it
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5. do_unregister_con_driver() can also be called on conditions which make it
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impossible for the driver to service console requests. This can happen
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with the framebuffer console that suddenly lost all of its drivers.
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