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authorSebastian Huber <sebastian.huber@embedded-brains.de>2016-12-20 11:30:49 +0100
committerSebastian Huber <sebastian.huber@embedded-brains.de>2016-12-21 11:34:14 +0100
commit5b8d5d06c199ac2651103ed11b6f7caea44d1f68 (patch)
treeb6cbb3e7c59e3b51a37e7d15a83f7a2624f18778 /bsp-howto
parent4b5b49988d8eaf78ea58e1b290159632ab547c3a (diff)
downloadrtems-docs-5b8d5d06c199ac2651103ed11b6f7caea44d1f68.tar.bz2
Remove Discrete Driver chapter
There exists no standard Discrete Driver in the RTEMS code base. Close #2851.
Diffstat (limited to 'bsp-howto')
-rw-r--r--bsp-howto/discrete.rst190
-rw-r--r--bsp-howto/index.rst1
2 files changed, 0 insertions, 191 deletions
diff --git a/bsp-howto/discrete.rst b/bsp-howto/discrete.rst
deleted file mode 100644
index 6607882..0000000
--- a/bsp-howto/discrete.rst
+++ /dev/null
@@ -1,190 +0,0 @@
-.. comment SPDX-License-Identifier: CC-BY-SA-4.0
-
-Discrete Driver
-***************
-
-The Discrete driver is responsible for providing an interface to Discrete
-Input/Outputs. The capabilities provided by this class of device driver are:
-
-- Initialize a Discrete I/O Board
-
-- Open a Particular Discrete Bitfield
-
-- Close a Particular Discrete Bitfield
-
-- Read from a Particular Discrete Bitfield
-
-- Write to a Particular Discrete Bitfield
-
-- Reset DACs
-
-- Reinitialize DACS
-
-Most discrete I/O devices are found on I/O cards that support many bits of
-discrete I/O on a single card. This driver model is centered on the notion of
-reading bitfields from the card.
-
-There are currently no discrete I/O device drivers included in the RTEMS source
-tree. The information provided in this chapter is based on drivers developed
-for applications using RTEMS. It is hoped that this driver model information
-can form the discrete I/O driver model that can be supported in future RTEMS
-distribution.
-
-Major and Minor Numbers
-=======================
-
-The ``major`` number of a device driver is its index in the RTEMS Device
-Address Table.
-
-A ``minor`` number is associated with each device instance managed by a
-particular device driver. An RTEMS minor number is an ``unsigned32`` entity.
-Convention calls for dividing the bits in the minor number down into categories
-that specify a particular bitfield. This results in categories like the
-following:
-
-- ``board`` - indicates the board a particular bitfield is located on
-
-- ``word`` - indicates the particular word of discrete bits the bitfield is
- located within
-
-- ``start`` - indicates the starting bit of the bitfield
-
-- ``width`` - indicates the width of the bitfield
-
-From the above, it should be clear that a single device driver can support
-multiple copies of the same board in a single system. The minor number is used
-to distinguish the devices.
-
-By providing a way to easily access a particular bitfield from the device
-driver, the application is insulated with knowing how to mask fields in and out
-of a discrete I/O.
-
-Discrete I/O Driver Configuration
-=================================
-
-There is not a standard discrete I/O driver configuration table but some fields
-are common across different drivers. The discrete I/O driver configuration
-table is typically an array of structures with each structure containing the
-information for a particular board. The following is a list of the type of
-information normally required to configure an discrete I/O board:
-
-``board_offset``
- is the base address of a board.
-
-``relay_initial_values``
- is an array of the values that should be written to each output word on the
- board during initialization. This allows the driver to start with the
- board's output in a known state.
-
-Initialize a Discrete I/O Board
-===============================
-
-At system initialization, the discrete I/O driver's initialization entry point
-will be invoked. As part of initialization, the driver will perform whatever
-board initializatin is required and then set all outputs to their configured
-initial state.
-
-The discrete I/O driver may register a device name for bitfields of particular
-interest to the system. Normally this will be restricted to the names of each
-word and, if the driver supports it, an "all words".
-
-Open a Particular Discrete Bitfield
-===================================
-
-This is the driver open call. Usually this call does nothing other than
-validate the minor number.
-
-With some drivers, it may be necessary to allocate memory when a particular
-device is opened. If that is the case, then this is often the place to do this
-operation.
-
-Close a Particular Discrete Bitfield
-====================================
-
-This is the driver close call. Usually this call does nothing.
-
-With some drivers, it may be necessary to allocate memory when a particular
-device is opened. If that is the case, then this is the place where that
-memory should be deallocated.
-
-Read from a Particular Discrete Bitfield
-========================================
-
-This corresponds to the driver read call. After validating the minor number
-and arguments, this call reads the indicated bitfield. A discrete I/O devices
-may have to store the last value written to a discrete output. If the bitfield
-is output only, saving the last written value gives the appearance that it can
-be read from also. If the bitfield is input, then it is sampled.
-
-.. note::
-
- Many discrete inputs have a tendency to bounce. The application may have to
- take account for bounces.
-
-The value returned is an ``unsigned32`` number representing the bitfield read.
-This value is stored in the ``argument_block`` passed in to the call.
-
-.. note::
-
- Some discrete I/O drivers have a special minor number used to access all
- discrete I/O bits on the board. If this special minor is used, then the
- area pointed to by ``argument_block`` must be the correct size.
-
-Write to a Particular Discrete Bitfield
-=======================================
-
-This corresponds to the driver write call. After validating the minor number
-and arguments, this call writes the indicated device. If the specified device
-is an ADC, then an error is usually returned.
-
-The value written is an ``unsigned32`` number representing the value to be
-written to the specified bitfield. This value is stored in the
-``argument_block`` passed in to the call.
-
-.. note::
-
- Some discrete I/O drivers have a special minor number used to access all
- discrete I/O bits on the board. If this special minor is used, then the
- area pointed to by ``argument_block`` must be the correct size.
-
-Disable Discrete Outputs
-========================
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point. When this IOCTL function is invoked, the discrete outputs are
-disabled.
-
-.. note::
-
- It may not be possible to disable/enable discrete output on all discrete I/O
- boards.
-
-Enable Discrete Outputs
-=======================
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point. When this IOCTL function is invoked, the discrete outputs are
-enabled.
-
-.. note::
-
- It may not be possible to disable/enable discrete output on all discrete
- I/O boards.
-
-Reinitialize Outputs
-====================
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point. When this IOCTL function is invoked, the discrete outputs are
-rewritten with the configured initial output values.
-
-Get Last Written Values
-=======================
-
-This is one of the IOCTL functions supported by the I/O control device driver
-entry point. When this IOCTL function is invoked, the following information is
-returned to the caller:
-
-- last value written to the specified output word
-
-- timestamp of when the last write was performed
diff --git a/bsp-howto/index.rst b/bsp-howto/index.rst
index 31cc0fa..f99118d 100644
--- a/bsp-howto/index.rst
+++ b/bsp-howto/index.rst
@@ -57,7 +57,6 @@ to the Community Project hosted at http://www.rtems.org.
networking
shared_memory_support
frame_buffer
- discrete
command
* :ref:`genindex`