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Diffstat (limited to 'c-user/io')
| -rw-r--r-- | c-user/io/background.rst | 162 | ||||
| -rw-r--r-- | c-user/io/directives.rst | 421 | ||||
| -rw-r--r-- | c-user/io/index.rst | 16 | ||||
| -rw-r--r-- | c-user/io/introduction.rst | 30 | ||||
| -rw-r--r-- | c-user/io/operations.rst | 26 |
5 files changed, 655 insertions, 0 deletions
diff --git a/c-user/io/background.rst b/c-user/io/background.rst new file mode 100644 index 0000000..28e5369 --- /dev/null +++ b/c-user/io/background.rst @@ -0,0 +1,162 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) + +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. diff --git a/c-user/io/directives.rst b/c-user/io/directives.rst new file mode 100644 index 0000000..d3098cb --- /dev/null +++ b/c-user/io/directives.rst @@ -0,0 +1,421 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) + +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. diff --git a/c-user/io/index.rst b/c-user/io/index.rst new file mode 100644 index 0000000..0b6ff6f --- /dev/null +++ b/c-user/io/index.rst @@ -0,0 +1,16 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 2020 embedded brains GmbH (http://www.embedded-brains.de) + +.. index:: device drivers +.. index:: IO Manager + +I/O Manager +*********** + +.. toctree:: + + introduction + background + operations + directives diff --git a/c-user/io/introduction.rst b/c-user/io/introduction.rst new file mode 100644 index 0000000..e097c7f --- /dev/null +++ b/c-user/io/introduction.rst @@ -0,0 +1,30 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) + +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: + +- :ref:`rtems_io_initialize` + +- :ref:`rtems_io_register_driver` + +- :ref:`rtems_io_unregister_driver` + +- :ref:`rtems_io_register_name` + +- :ref:`rtems_io_lookup_name` + +- :ref:`rtems_io_open` + +- :ref:`rtems_io_close` + +- :ref:`rtems_io_read` + +- :ref:`rtems_io_write` + +- :ref:`rtems_io_control` diff --git a/c-user/io/operations.rst b/c-user/io/operations.rst new file mode 100644 index 0000000..ec0212d --- /dev/null +++ b/c-user/io/operations.rst @@ -0,0 +1,26 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) + +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. |