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diff --git a/c-user/io_manager.rst b/c-user/io_manager.rst deleted file mode 100644 index 12282d7..0000000 --- a/c-user/io_manager.rst +++ /dev/null @@ -1,636 +0,0 @@ -.. SPDX-License-Identifier: CC-BY-SA-4.0 - -.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) - -.. index:: device drivers -.. index:: IO Manager - -I/O Manager -*********** - -Introduction -============ - -The input/output interface manager provides a well-defined mechanism for -accessing device drivers and a structured methodology for organizing device -drivers. The directives provided by the I/O manager are: - -- rtems_io_initialize_ - Initialize a device driver - -- rtems_io_register_driver_ - Register a device driver - -- rtems_io_unregister_driver_ - Unregister a device driver - -- rtems_io_register_name_ - Register a device name - -- rtems_io_lookup_name_ - Look up a device name - -- rtems_io_open_ - Open a device - -- rtems_io_close_ - Close a device - -- rtems_io_read_ - Read from a device - -- rtems_io_write_ - Write to a device - -- rtems_io_control_ - Special device services - -Background -========== - -.. index:: Device Driver Table - -Device Driver Table -------------------- - -Each application utilizing the RTEMS I/O manager must specify the address of a -Device Driver Table in its Configuration Table. This table contains each device -driver's entry points that is to be initialised by RTEMS during initialization. -Each device driver may contain the following entry points: - -- Initialization - -- Open - -- Close - -- Read - -- Write - -- Control - -If the device driver does not support a particular entry point, then that entry -in the Configuration Table should be NULL. RTEMS will return -``RTEMS_SUCCESSFUL`` as the executive's and zero (0) as the device driver's -return code for these device driver entry points. - -Applications can register and unregister drivers with the RTEMS I/O manager -avoiding the need to have all drivers statically defined and linked into this -table. - -The :file:`confdefs.h` entry ``CONFIGURE_MAXIMUM_DRIVERS`` configures the -number of driver slots available to the application. - -.. index:: major device number -.. index:: minor device number - -Major and Minor Device Numbers ------------------------------- - -Each call to the I/O manager must provide a device's major and minor numbers as -arguments. The major number is the index of the requested driver's entry -points in the Device Driver Table, and is used to select a specific device -driver. The exact usage of the minor number is driver specific, but is -commonly used to distinguish between a number of devices controlled by the same -driver. - -.. index:: rtems_device_major_number -.. index:: rtems_device_minor_number - -The data types ``rtems_device_major_number`` and ``rtems_device_minor_number`` -are used to manipulate device major and minor numbers, respectively. - -.. index:: device names - -Device Names ------------- - -The I/O Manager provides facilities to associate a name with a particular -device. Directives are provided to register the name of a device and to look -up the major/minor number pair associated with a device name. - -Device Driver Environment -------------------------- - -Application developers, as well as device driver developers, must be aware of -the following regarding the RTEMS I/O Manager: - -- A device driver routine executes in the context of the invoking task. Thus - if the driver blocks, the invoking task blocks. - -- The device driver is free to change the modes of the invoking task, although - the driver should restore them to their original values. - -- Device drivers may be invoked from ISRs. - -- Only local device drivers are accessible through the I/O manager. - -- A device driver routine may invoke all other RTEMS directives, including I/O - directives, on both local and global objects. - -Although the RTEMS I/O manager provides a framework for device drivers, it -makes no assumptions regarding the construction or operation of a device -driver. - -.. index:: runtime driver registration - -Runtime Driver Registration ---------------------------- - -Board support package and application developers can select wether a device -driver is statically entered into the default device table or registered at -runtime. - -Dynamic registration helps applications where: - -- The BSP and kernel libraries are common to a range of applications for a - specific target platform. An application may be built upon a common library - with all drivers. The application selects and registers the drivers. Uniform - driver name lookup protects the application. - -- The type and range of drivers may vary as the application probes a bus during - initialization. - -- Support for hot swap bus system such as Compact PCI. - -- Support for runtime loadable driver modules. - -.. index:: device driver interface - -Device Driver Interface ------------------------ - -When an application invokes an I/O manager directive, RTEMS determines which -device driver entry point must be invoked. The information passed by the -application to RTEMS is then passed to the correct device driver entry point. -RTEMS will invoke each device driver entry point assuming it is compatible with -the following prototype: - -.. code-block:: c - - rtems_device_driver io_entry( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument_block - ); - -The format and contents of the parameter block are device driver and entry -point dependent. - -It is recommended that a device driver avoid generating error codes which -conflict with those used by application components. A common technique used to -generate driver specific error codes is to make the most significant part of -the status indicate a driver specific code. - -Device Driver Initialization ----------------------------- - -RTEMS automatically initializes all device drivers when multitasking is -initiated via the ``rtems_initialize_executive`` directive. RTEMS initializes -the device drivers by invoking each device driver initialization entry point -with the following parameters: - -``major`` - the major device number for this device driver. - -``minor`` - zero. - -``argument_block`` - will point to the Configuration Table. - -The returned status will be ignored by RTEMS. If the driver cannot -successfully initialize the device, then it should invoke the -fatal_error_occurred directive. - -Operations -========== - -Register and Lookup Name ------------------------- - -The ``rtems_io_register`` directive associates a name with the specified device -(i.e. major/minor number pair). Device names are typically registered as part -of the device driver initialization sequence. The ``rtems_io_lookup`` -directive is used to determine the major/minor number pair associated with the -specified device name. The use of these directives frees the application from -being dependent on the arbitrary assignment of major numbers in a particular -application. No device naming conventions are dictated by RTEMS. - -Accessing an Device Driver --------------------------- - -The I/O manager provides directives which enable the application program to -utilize device drivers in a standard manner. There is a direct correlation -between the RTEMS I/O manager directives ``rtems_io_initialize``, -``rtems_io_open``, ``rtems_io_close``, ``rtems_io_read``, ``rtems_io_write``, -and ``rtems_io_control`` and the underlying device driver entry points. - -Directives -========== - -This section details the I/O manager's directives. A subsection is dedicated -to each of this manager's directives and describes the calling sequence, -related constants, usage, and status codes. - -.. raw:: latex - - \clearpage - -.. index:: register a device driver -.. index:: rtems_io_register_driver - -.. _rtems_io_register_driver: - -IO_REGISTER_DRIVER - Register a device driver ---------------------------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_register_driver( - rtems_device_major_number major, - rtems_driver_address_table *driver_table, - rtems_device_major_number *registered_major - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully registered - * - ``RTEMS_INVALID_ADDRESS`` - - invalid registered major pointer - * - ``RTEMS_INVALID_ADDRESS`` - - invalid driver table - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - * - ``RTEMS_TOO_MANY`` - - no available major device table slot - * - ``RTEMS_RESOURCE_IN_USE`` - - major device number entry in use - -DESCRIPTION: - This directive attempts to add a new device driver to the Device Driver - Table. The user can specify a specific major device number via the - directive's ``major`` parameter, or let the registration routine find the - next available major device number by specifing a major number of - ``0``. The selected major device number is returned via the - ``registered_major`` directive parameter. The directive automatically - allocation major device numbers from the highest value down. - - This directive automatically invokes the ``IO_INITIALIZE`` directive if the - driver address table has an initialization and open entry. - - The directive returns ``RTEMS_TOO_MANY`` if Device Driver Table is full, - and ``RTEMS_RESOURCE_IN_USE`` if a specific major device number is - requested and it is already in use. - -NOTES: - The Device Driver Table size is specified in the Configuration Table - condiguration. This needs to be set to maximum size the application - requires. - -.. raw:: latex - - \clearpage - -.. index:: unregister a device driver -.. index:: rtems_io_unregister_driver - -.. _rtems_io_unregister_driver: - -IO_UNREGISTER_DRIVER - Unregister a device driver -------------------------------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_unregister_driver( - rtems_device_major_number major - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully registered - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive removes a device driver from the Device Driver Table. - -NOTES: - Currently no specific checks are made and the driver is not closed. - -.. raw:: latex - - \clearpage - -.. index:: initialize a device driver -.. index:: rtems_io_initialize - -.. _rtems_io_initialize: - -IO_INITIALIZE - Initialize a device driver ------------------------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_initialize( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive calls the device driver initialization routine specified in - the Device Driver Table for this major number. This directive is - automatically invoked for each device driver when multitasking is initiated - via the initialize_executive directive. - - A device driver initialization module is responsible for initializing all - hardware and data structures associated with a device. If necessary, it can - allocate memory to be used during other operations. - -NOTES: - This directive may or may not cause the calling task to be preempted. This - is dependent on the device driver being initialized. - -.. raw:: latex - - \clearpage - -.. index:: register device -.. index:: rtems_io_register_name - -.. _rtems_io_register_name: - -IO_REGISTER_NAME - Register a device ------------------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_register_name( - const char *name, - rtems_device_major_number major, - rtems_device_minor_number minor - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_TOO_MANY`` - - too many devices registered - -DESCRIPTION: - This directive associates name with the specified major/minor number pair. - -NOTES: - This directive will not cause the calling task to be preempted. - -.. raw:: latex - - \clearpage - -.. index:: lookup device major and minor number -.. index:: rtems_io_lookup_name - -.. _rtems_io_lookup_name: - -IO_LOOKUP_NAME - Lookup a device --------------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_lookup_name( - const char *name, - rtems_driver_name_t *device_info - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_UNSATISFIED`` - - name not registered - -DESCRIPTION: - This directive returns the major/minor number pair associated with the - given device name in ``device_info``. - -NOTES: - This directive will not cause the calling task to be preempted. - -.. raw:: latex - - \clearpage - -.. index:: open a devive -.. index:: rtems_io_open - -.. _rtems_io_open: - -IO_OPEN - Open a device ------------------------ - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_open( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive calls the device driver open routine specified in the Device - Driver Table for this major number. The open entry point is commonly used - by device drivers to provide exclusive access to a device. - -NOTES: - This directive may or may not cause the calling task to be preempted. This - is dependent on the device driver being invoked. - -.. raw:: latex - - \clearpage - -.. index:: close a device -.. index:: rtems_io_close - -.. _rtems_io_close: - -IO_CLOSE - Close a device -------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_close( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive calls the device driver close routine specified in the - Device Driver Table for this major number. The close entry point is - commonly used by device drivers to relinquish exclusive access to a device. - -NOTES: - This directive may or may not cause the calling task to be preempted. This - is dependent on the device driver being invoked. - -.. raw:: latex - - \clearpage - -.. index:: read from a device -.. index:: rtems_io_read - -.. _rtems_io_read: - -IO_READ - Read from a device ----------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_read( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive calls the device driver read routine specified in the Device - Driver Table for this major number. Read operations typically require a - buffer address as part of the argument parameter block. The contents of - this buffer will be replaced with data from the device. - -NOTES: - This directive may or may not cause the calling task to be preempted. This - is dependent on the device driver being invoked. - -.. raw:: latex - - \clearpage - -.. index:: write to a device -.. index:: rtems_io_write - -.. _rtems_io_write: - -IO_WRITE - Write to a device ----------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_write( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive calls the device driver write routine specified in the - Device Driver Table for this major number. Write operations typically - require a buffer address as part of the argument parameter block. The - contents of this buffer will be sent to the device. - -NOTES: - This directive may or may not cause the calling task to be preempted. This - is dependent on the device driver being invoked. - -.. raw:: latex - - \clearpage - -.. index:: special device services -.. index:: IO Control -.. index:: rtems_io_control - -.. _rtems_io_control: - -IO_CONTROL - Special device services ------------------------------------- - -CALLING SEQUENCE: - .. code-block:: c - - rtems_status_code rtems_io_control( - rtems_device_major_number major, - rtems_device_minor_number minor, - void *argument - ); - -DIRECTIVE STATUS CODES: - .. list-table:: - :class: rtems-table - - * - ``RTEMS_SUCCESSFUL`` - - successfully initialized - * - ``RTEMS_INVALID_NUMBER`` - - invalid major device number - -DESCRIPTION: - This directive calls the device driver I/O control routine specified in the - Device Driver Table for this major number. The exact functionality of the - driver entry called by this directive is driver dependent. It should not - be assumed that the control entries of two device drivers are compatible. - For example, an RS-232 driver I/O control operation may change the baud - rate of a serial line, while an I/O control operation for a floppy disk - driver may cause a seek operation. - -NOTES: - This directive may or may not cause the calling task to be preempted. This - is dependent on the device driver being invoked. |