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authorSebastian Huber <sebastian.huber@embedded-brains.de>2016-12-23 14:38:35 +0100
committerSebastian Huber <sebastian.huber@embedded-brains.de>2016-12-23 14:38:35 +0100
commit5bb51a43d1c770dfaddd484f0e5f6d104b8df92e (patch)
treee057296be64c8788b4660092c69a7e6fc21cef36 /bsp-howto
parent3b42c96764c8aa49ce4e4ec381b1187d375d6e8f (diff)
downloadrtems-docs-5bb51a43d1c770dfaddd484f0e5f6d104b8df92e.tar.bz2
Update Console Driver chapter
Close #2785. Close #2838.
Diffstat (limited to 'bsp-howto')
-rw-r--r--bsp-howto/console.rst728
1 files changed, 346 insertions, 382 deletions
diff --git a/bsp-howto/console.rst b/bsp-howto/console.rst
index 64e3c3a..46ffb0a 100644
--- a/bsp-howto/console.rst
+++ b/bsp-howto/console.rst
@@ -7,240 +7,171 @@
Console Driver
**************
-Introduction
-============
-
-This chapter describes the operation of a console driver using the RTEMS POSIX
-Termios support. Traditionally RTEMS has referred to all serial device drivers
-as console device drivers. A console driver can be used to do raw data
-processing in addition to the "normal" standard input and output device
-functions required of a console.
-
-The serial driver may be called as the consequence of a C Library call such as
-``printf`` or ``scanf`` or directly via the``read`` or ``write`` system calls.
-There are two main functioning modes:
-
-- console: formatted input/output, with special characters (end of line,
- tabulations, etc.) recognition and processing,
-
-- raw: permits raw data processing.
-
-One may think that two serial drivers are needed to handle these two types of
-data, but Termios permits having only one driver.
-
-Termios
-=======
-
-Termios is a standard for terminal management, included in the POSIX 1003.1b
-standard. As part of the POSIX and Open Group Single UNIX Specification, is
-commonly provided on UNIX implementations. The Open Group has the termios
-portion of the POSIX standard online at
-http://opengroup.org/onlinepubs/007908775/xbd/termios.html. The requirements
-for the ``<termios.h>`` file are also provided and are at
-http://opengroup.org/onlinepubs/007908775/xsh/termios.h.html.
-
-Having RTEMS support for Termios is beneficial because:
-
-- from the user's side because it provides standard primitive operations to
- access the terminal and change configuration settings. These operations are
- the same under UNIX and RTEMS.
-
-- from the BSP developer's side because it frees the developer from dealing
- with buffer states and mutual exclusions on them. Early RTEMS console device
- drivers also did their own special character processing.
-
-- it is part of an internationally recognized standard.
-
-- it makes porting code from other environments easier.
-
-Termios support includes:
-
-- raw and console handling,
-
-- blocking or non-blocking characters receive, with or without Timeout.
-
-At this time, RTEMS documentation does not include a thorough discussion of the
-Termios functionality. For more information on Termios, type ``man termios``
-on a Unix box or point a web browser athttp://www.freebsd.org/cgi/man.cgi.
-
-Driver Functioning Modes
-========================
-
-There are generally three main functioning modes for an UART (Universal
-Asynchronous Receiver-Transmitter, i.e. the serial chip):
-
-- polled mode
-
-- interrupt driven mode
-
-- task driven mode
-
-In polled mode, the processor blocks on sending/receiving characters. This
-mode is not the most efficient way to utilize the UART. But polled mode is
-usually necessary when one wants to print an error message in the event of a
-fatal error such as a fatal error in the BSP. This is also the simplest mode
-to program. Polled mode is generally preferred if the serial port is to be
-used primarily as a debug console. In a simple polled driver, the software
-will continuously check the status of the UART when it is reading or writing to
-the UART. Termios improves on this by delaying the caller for 1 clock tick
-between successive checks of the UART on a read operation.
-
-In interrupt driven mode, the processor does not block on sending/receiving
-characters. Data is buffered between the interrupt service routine and
-application code. Two buffers are used to insulate the application from the
-relative slowness of the serial device. One of the buffers is used for
-incoming characters, while the other is used for outgoing characters.
+.. warning::
+ The low-level driver API changed between RTEMS 4.10 and RTEMS 4.11. The
+ legacy callback API is still supported, but its use is discouraged. The
+ following functions are deprecated:
-An interrupt is raised when a character is received by the UART. The interrupt
-subroutine places the incoming character at the end of the input buffer. When
-an application asks for input, the characters at the front of the buffer are
-returned.
+ - :c:func:`rtems_termios_open()`
-When the application prints to the serial device, the outgoing characters are
-placed at the end of the output buffer. The driver will place one or more
-characters in the UART (the exact number depends on the UART) An interrupt will
-be raised when all the characters have been transmitted. The interrupt service
-routine has to send the characters remaining in the output buffer the same way.
-When the transmitting side of the UART is idle, it is typically necessary to
-prime the transmitter before the first interrupt will occur.
+ - :c:func:`rtems_termios_close()`
-The task driven mode is similar to interrupt driven mode, but the actual data
-processing is done in dedicated tasks instead of interrupt routines.
+ This manual describes the new API.
-Serial Driver Functioning Overview
-==================================
-
-The following Figure shows how a Termios driven serial driver works: Figure not
-included in ASCII version
-
-The following list describes the basic flow.
-
-- the application programmer uses standard C library call (printf, scanf, read,
- write, etc.),
-
-- C library (ctx.g. RedHat (formerly Cygnus) Newlib) calls the RTEMS system
- call interface. This code can be found in the:file:`cpukit/libcsupport/src`
- directory.
-
-- Glue code calls the serial driver entry routines.
-
-Basics
-------
-
-The low-level driver API changed between RTEMS 4.10 and RTEMS 4.11. The legacy
-callback API is still supported, but its use is discouraged. The following
-functions are deprecated:
-
-- ``rtems_termios_open()`` - use ``rtems_termios_device_open()`` in combination
- with ``rtems_termios_device_install()`` instead.
-
-- ``rtems_termios_close()`` - use ``rtems_termios_device_close()`` instead.
-
-This manual describes the new API. A new console driver should consist of
-three parts.
+Introduction
+============
-- The basic console driver functions using the Termios support. Add this the
- BSPs Makefile.am:
+This chapter describes the operation of a console driver using the RTEMS POSIX
+Termios support. Traditionally, RTEMS has referred to all serial device drivers
+as console drivers.
+`Termios <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap11.html>`_
+is defined by IEEE Std 1003.1-2008 (POSIX.1-2008). It supports various modes
+of operations at application level. This chapter focuses on the low-level
+serial device driver. Additional Termios information can be found in the
+`Linux TERMIOS(3) <http://man7.org/linux/man-pages/man3/termios.3.html>`_
+manpage or the
+`FreeBSD TERMIOS(4) <https://www.freebsd.org/cgi/man.cgi?query=termios&sektion=4>`_
+manpage.
+
+There are the following software layers.
+
++-------------------------+
+| Application |
++-------------------------+
+| Termios |
++-------------------------+
+| Low-Level Device Driver |
++-------------------------+
+
+In the default application configuration RTEMS opens during system
+initialization a :file:`/dev/console` device file to create the file
+descriptors 0, 1 and 2 used for standard input, output and error, respectively.
+The corresponding device driver is usually a Termios serial device driver
+described here. The standard file descriptors are used by standard C library
+calls such as :c:func:`printf` or :c:func:`scanf` or directly via the
+:c:func:`read` or :c:func:`write` system calls.
+
+Build System and Files
+======================
+
+A new serial device driver should consist of three parts.
+
+- A section in the BSPs Makefile.am:
.. code-block:: makefile
[...]
libbsp_a_SOURCES += ../../shared/console-termios.c
+ libbsp_a_SOURCES += console/console.c
[...]
-- A general serial module specific low-level driver providing the handler table
- for the Termios ``rtems_termios_device_install()`` function. This low-level
- driver could be used for more than one BSP.
-
-- A BSP specific initialization routine ``console_initialize()``, that calls
- ``rtems_termios_device_install()`` providing a low-level driver context for
- each installed device.
+- A general serial device specific low-level driver providing the handler table
+ and the device context specialization for the Termios
+ :c:func:`rtems_termios_device_install()` function. This low-level driver
+ could be used for more than one BSP.
-You need to provide a device handler structure for the Termios device
-interface. The functions are described later in this chapter. The first open
-and set attributes handler return a boolean status to indicate success (true)
-or failure (false). The polled read function returns an unsigned character in
-case one is available or minus one otherwise.
+- A BSP-specific initialization routine :c:func:`console_initialize()`, that calls
+ :c:func:`rtems_termios_device_install()` providing a low-level driver context for
+ each installed device. This is usually defined in the file
+ :file:`console/console.c` relative to the BSP base directory.
-If you want to use polled IO it should look like the following. Termios must
-be told the addresses of the handler that are to be used for simple character
-IO, i.e. pointers to the ``my_driver_poll_read()`` and
-``my_driver_poll_write()`` functions described later in `Termios and Polled
-IO`_.
-
-.. code-block:: c
-
- const rtems_termios_handler my_driver_handler_polled = {
- .first_open = my_driver_first_open,
- .last_close = my_driver_last_close,
- .poll_read = my_driver_poll_read,
- .write = my_driver_poll_write,
- .set_attributes = my_driver_set_attributes,
- .stop_remote_tx = NULL,
- .start_remote_tx = NULL,
- .mode = TERMIOS_POLLED
- }
-
-For an interrupt driven implementation you need the following. The driver
-functioning is quite different in this mode. There is no device driver read
-handler to be passed to Termios. Indeed a ``console_read()`` call returns the
-contents of Termios input buffer. This buffer is filled in the driver
-interrupt subroutine, see also `Termios and Interrupt Driven IO`_. The driver
-is responsible for providing a pointer to the``my_driver_interrupt_write()``
-function.
-
-.. code-block:: c
-
- const rtems_termios_handler my_driver_handler_interrupt = {
- .first_open = my_driver_first_open,
- .last_close = my_driver_last_close,
- .poll_read = NULL,
- .write = my_driver_interrupt_write,
- .set_attributes = my_driver_set_attributes,
- .stopRemoteTx = NULL,
- .stop_remote_tx = NULL,
- .start_remote_tx = NULL,
- .mode = TERMIOS_IRQ_DRIVEN
- };
-
-You can also provide hander for remote transmission control. This is not
-covered in this manual, so they are set to ``NULL`` in the above examples.
-
-The low-level driver should provide a data structure for its device context.
-The initialization routine must provide a context for each installed device via
-``rtems_termios_device_install()``. For simplicity of the console
-initialization example the device name is also present. Here is an example
-header file.
+The low-level driver should provide a specialization of the Termios device
+context. The initialization routine must provide a context for each installed
+device via :c:func:`rtems_termios_device_install()`. Here is an example header
+file for a low-level serial device driver.
.. code-block:: c
#ifndef MY_DRIVER_H
#define MY_DRIVER_H
+ #include <some-chip/serial.h>
+
#include <rtems/termiostypes.h>
- #include <some-chip-header.h>
- /* Low-level driver specific data structure */
+ /* My low-level driver specialization of Termios device context */
typedef struct {
rtems_termios_device_context base;
const char *device_name;
- volatile module_register_block *regs;
+ volatile some_chip_registers *regs;
/* More stuff */
} my_driver_context;
- extern const rtems_termios_handler my_driver_handler_polled;
- extern const rtems_termios_handler my_driver_handler_interrupt;
+ extern const rtems_termios_device_handler my_driver_handler_polled;
+
+ extern const rtems_termios_device_handler my_driver_handler_interrupt;
#endif /* MY_DRIVER_H */
-Termios and Polled IO
----------------------
+Driver Functioning Modes
+========================
+
+There are four main functioning modes for a Termios serial device driver. The
+mode must be set during device creation and cannot be changed afterwards.
+
+Polled Mode (`TERMIOS_POLLED`)
+ In polled mode, the processor blocks on sending/receiving characters. This
+ mode is not the most efficient way to utilize the serial device. But polled
+ mode is usually necessary when one wants to print an error message in the
+ event of a fatal error such as a fatal error in the BSP. This is also the
+ simplest mode to program. Polled mode is generally preferred if the serial
+ device is to be used primarily as a debug console. In a simple polled
+ driver, the software will continuously check the status of the serial
+ device when it is reading or writing to the serial device. Termios
+ improves on this by delaying the caller for one clock tick between
+ successive checks of the serial device on a read operation.
+
+Interrupt Driven Mode (`TERMIOS_IRQ_DRIVEN`)
+ In interrupt driven mode, the processor does not block on sending/receiving
+ characters. Data is buffered between the interrupt service routine and
+ application code. Two buffers are used to insulate the application from
+ the relative slowness of the serial device. One of the buffers is used for
+ incoming characters, while the other is used for outgoing characters.
+
+ An interrupt is raised when a character is received by the serial device.
+ The interrupt routine places the incoming character at the end of the input
+ buffer. When an application asks for input, the characters at the front of
+ the buffer are returned.
+
+ When the application prints to the serial device, the outgoing characters
+ are placed at the end of the output buffer. The driver will place one or
+ more characters in the serial device (the exact number depends on the
+ serial device) An interrupt will be raised when all the characters have
+ been transmitted. The interrupt service routine has to send the characters
+ remaining in the output buffer the same way. When the transmitting side of
+ the serial device is idle, it is typically necessary to prime the
+ transmitter before the first interrupt will occur.
+
+Interrupt Server Driven Mode (`TERMIOS_IRQ_SERVER_DRIVEN`)
+ The interrupt server driven mode is identical to the interrupt driven mode,
+ except that a mutex is used to protect the low-level device state instead
+ of an interrupt lock (disabled interrupts). Use this mode in case the
+ serial device is connected via I2C or SPI and the I2C or SPI framework is
+ used.
+
+Task Driven Mode (`TERMIOS_TASK_DRIVEN`)
+ The task driven mode is similar to interrupt driven mode, but the actual
+ data processing is done in dedicated tasks instead of interrupt routines.
+
+Polled Mode
+===========
+
+The handler table for the polled mode should look like the following.
-The following handler are provided by the low-level driver and invoked by
-Termios for simple character IO.
+.. code-block:: c
+
+ const rtems_termios_device_handler my_driver_handler_polled = {
+ .first_open = my_driver_first_open,
+ .last_close = my_driver_last_close,
+ .poll_read = my_driver_poll_read,
+ .write = my_driver_poll_write,
+ .set_attributes = my_driver_set_attributes,
+ .ioctl = my_driver_ioctl, /* optional, may be NULL */
+ .mode = TERMIOS_POLLED
+ }
-The ``my_driver_poll_write()`` routine is responsible for writing ``n``
-characters from ``buf`` to the serial device specified by ``tty``.
+The :c:func:`my_driver_poll_write()` routine is responsible for writing ``n``
+characters from ``buf`` to the serial device specified by ``base``.
.. code-block:: c
@@ -250,72 +181,94 @@ characters from ``buf`` to the serial device specified by ``tty``.
size_t n
)
{
- my_driver_context *ctx = (my_driver_context *) base;
- size_t i;
- /* Write */
- for (i = 0; i < n; ++i) {
- my_driver_write_char(ctx, buf[i]);
+ my_driver_context *ctx;
+
+ ctx = (my_driver_context *) base;
+
+ for ( i = 0 ; i < n ; ++i ) {
+ my_driver_write_char( ctx, buf[ i ] );
}
}
-The ``my_driver_poll_read`` routine is responsible for reading a single
-character from the serial device specified by ``tty``. If no character is
-available, then the routine should return minus one.
+The :c:func:`my_driver_poll_read` routine is responsible for reading a single
+character from the serial device specified by ``base``. If no character is
+available, then the routine should immediately return minus one.
.. code-block:: c
- static int my_driver_poll_read(rtems_termios_device_context *base)
+ static int my_driver_poll_read( rtems_termios_device_context *base )
{
- my_driver_context *ctx = (my_driver_context *) base;
- /* Check if a character is available */
- if (my_driver_can_read_char(ctx)) {
- /* Return the character */
- return my_driver_read_char(ctx);
+ my_driver_context *ctx;
+ size_t i;
+
+ ctx = (my_driver_context *) base;
+
+ if ( my_driver_can_read_char( ctx ) ) {
+ /* Return the character (must be unsigned) */
+ return my_driver_read_char( ctx );
} else {
- /* Return an error status */
+ /* Return -1 to indicate that no character is available */
return -1;
}
}
-Termios and Interrupt Driven IO
--------------------------------
+Interrupt Driven Mode
+=====================
-The UART generally generates interrupts when it is ready to accept or to emit a
-number of characters. In this mode, the interrupt subroutine is the core of
-the driver.
+The handler table for the interrupt driven mode should look like the following.
-The ``my_driver_interrupt_handler()`` is responsible for processing
-asynchronous interrupts from the UART. There may be multiple interrupt
-handlers for a single UART. Some UARTs can generate a unique interrupt vector
-for each interrupt source such as a character has been received or the
-transmitter is ready for another character.
+.. code-block:: c
-In the simplest case, the ``my_driver_interrupt_handler()`` will have to check
-the status of the UART and determine what caused the interrupt. The following
-describes the operation of an ``my_driver_interrupt_handler`` which has to do
-this:
+ const rtems_termios_device_handler my_driver_handler_interrupt = {
+ .first_open = my_driver_first_open,
+ .last_close = my_driver_last_close,
+ .poll_read = NULL,
+ .write = my_driver_interrupt_write,
+ .set_attributes = my_driver_set_attributes,
+ .ioctl = my_driver_ioctl, /* optional, may be NULL */
+ .mode = TERMIOS_IRQ_DRIVEN
+ };
+
+There is no device driver read handler to be passed to Termios. Indeed a
+:c:func:`read()` call returns the contents of Termios input buffer. This
+buffer is filled in the driver interrupt routine.
+
+A serial device generally generates interrupts when it is ready to accept or to
+emit a number of characters. In this mode, the interrupt routine is the core
+of the driver.
+
+The :c:func:`my_driver_interrupt_handler` is responsible for processing
+asynchronous interrupts from the serial device. There may be multiple
+interrupt handlers for a single serial device. Some serial devices can
+generate a unique interrupt vector for each interrupt source such as a
+character has been received or the transmitter is ready for another character.
+
+In the simplest case, the :c:func:`my_driver_interrupt_handler` will have to
+check the status of the serial device and determine what caused the interrupt.
+The following describes the operation of an
+:c:func:`my_driver_interrupt_handler` which has to do this:
.. code-block:: c
- static void my_driver_interrupt_handler(
- rtems_vector_number vector,
- void *arg
- )
+ static void my_driver_interrupt_handler( void *arg )
{
- rtems_termios_tty *tty = arg;
- my_driver_context *ctx = rtems_termios_get_device_context(tty);
- char buf[N];
- size_t n;
+ rtems_termios_tty *tty;
+ my_driver_context *ctx;
+ char buf[N];
+ size_t n;
+
+ tty = arg;
+ ctx = rtems_termios_get_device_context( tty );
/*
* Check if we have received something. The function reads the
* received characters from the device and stores them in the
* buffer. It returns the number of read characters.
*/
- n = my_driver_read_received_chars(ctx, buf, N);
- if (n > 0) {
+ n = my_driver_read_received_chars( ctx, buf, N );
+ if ( n > 0 ) {
/* Hand the data over to the Termios infrastructure */
- rtems_termios_enqueue_raw_characters(tty, buf, n);
+ rtems_termios_enqueue_raw_characters( tty, buf, n );
}
/*
@@ -323,19 +276,19 @@ this:
* the number of transmitted characters since the last write to the
* device.
*/
- n = my_driver_transmitted_chars(ctx);
- if (n > 0) {
+ n = my_driver_transmitted_chars( ctx );
+ if ( n > 0 ) {
/*
* Notify Termios that we have transmitted some characters. It
* will call now the interrupt write function if more characters
* are ready for transmission.
*/
- rtems_termios_dequeue_characters(tty, n);
+ rtems_termios_dequeue_characters( tty, n );
}
}
-The ``my_driver_interrupt_write()`` function is responsible for telling the
-device that the ``n`` characters at ``buf`` are to be transmitted. It the
+The :c:func:`my_driver_interrupt_write()` handler is responsible for telling
+the device that the ``n`` characters at ``buf`` are to be transmitted. It the
value ``n`` is zero to indicate that no more characters are to send. The
driver can disable the transmit interrupts now. This routine is invoked either
from task context with disabled interrupts to start a new transmission process
@@ -354,102 +307,34 @@ character.
size_t n
)
{
- my_driver_context *ctx = (my_driver_context *) base;
+ my_driver_context *ctx;
- /*
- * Tell the device to transmit some characters from buf (less than
- * or equal to n). When the device is finished it should raise an
- * interrupt. The interrupt handler will notify Termios that these
- * characters have been transmitted and this may trigger this write
- * function again. You may have to store the number of outstanding
- * characters in the device data structure.
- */
- /*
- * Termios will set n to zero to indicate that the transmitter is
- * now inactive. The output buffer is empty in this case. The
- * driver may disable the transmit interrupts now.
- */
- }
-
-Initialization
---------------
-
-The BSP specific driver initialization is called once during the RTEMS
-initialization process.
-
-The ``console_initialize()`` function may look like this:
-
-.. code-block:: c
-
- #include <my-driver.h>
- #include <rtems/console.h>
- #include <bsp.h>
- #include <bsp/fatal.h>
-
- static my_driver_context driver_context_table[M] = { /* Some values */ };
-
- rtems_device_driver console_initialize(
- rtems_device_major_number major,
- rtems_device_minor_number minor,
- void *arg
- )
- {
- rtems_status_code sc;
- #ifdef SOME_BSP_USE_INTERRUPTS
- const rtems_termios_handler *handler = &my_driver_handler_interrupt;
- #else
- const rtems_termios_handler *handler = &my_driver_handler_polled;
- #endif
-
- /*
- * Initialize the Termios infrastructure. If Termios has already
- * been initialized by another device driver, then this call will
- * have no effect.
- */
- rtems_termios_initialize();
-
- /* Initialize each device */
- for (
- minor = 0;
- minor < RTEMS_ARRAY_SIZE(driver_context_table);
- ++minor
- ) {
- my_driver_context *ctx = &driver_context_table[minor];
+ ctx = (my_driver_context *) base;
+ if ( n > 0 ) {
/*
- * Install this device in the file system and Termios. In order
- * to use the console (i.e. being able to do printf, scanf etc.
- * on stdin, stdout and stderr), one device must be registered as
- * "/dev/console" (CONSOLE_DEVICE_NAME).
+ * Tell the device to transmit some characters from buf (less than
+ * or equal to n). When the device is finished it should raise an
+ * interrupt. The interrupt handler will notify Termios that these
+ * characters have been transmitted and this may trigger this write
+ * function again. You may have to store the number of outstanding
+ * characters in the device data structure.
+ */
+ } else {
+ /*
+ * Termios will set n to zero to indicate that the transmitter is
+ * now inactive. The output buffer is empty in this case. The
+ * driver may disable the transmit interrupts now.
*/
- sc = rtems_termios_device_install(
- ctx->device_name,
- major,
- minor,
- handler,
- NULL,
- ctx
- );
- if (sc != RTEMS_SUCCESSFUL) {
- bsp_fatal(SOME_BSP_FATAL_CONSOLE_DEVICE_INSTALL);
- }
}
-
- return RTEMS_SUCCESSFUL;
}
-Opening a serial device
------------------------
+First Open
+==========
-The ``console_open()`` function provided by :file:`console-termios.c` is called
-whenever a serial device is opened. The device registered as
-``"/dev/console"`` (``CONSOLE_DEVICE_NAME``) is opened automatically during
-RTEMS initialization. For instance, if UART channel 2 is registered as
-``"/dev/tty1"``, the ``console_open()`` entry point will be called as the
-result of an ``fopen("/dev/tty1", mode)`` in the application.
-
-During the first open of the device Termios will call the
-``my_driver_first_open()`` handler.
+Upon first open of the device, the :c:func:`my_driver_first_open` handler is
+called by Termios. The device registered as :file:`/dev/console` (or
+``CONSOLE_DEVICE_NAME``) is opened automatically during RTEMS initialization.
.. code-block:: c
@@ -460,9 +345,11 @@ During the first open of the device Termios will call the
rtems_libio_open_close_args_t *args
)
{
- my_driver_context *ctx = (my_driver_context *) base;
- rtems_status_code sc;
- bool ok;
+ my_driver_context *ctx;
+ rtems_status_code sc;
+ bool ok;
+
+ ctx = (my_driver_context *) base;
/*
* You may add some initialization code here.
@@ -473,22 +360,22 @@ During the first open of the device Termios will call the
* the boot loader. This function accepts only exact Termios baud
* values.
*/
- sc = rtems_termios_set_initial_baud(tty, MY_DRIVER_BAUD_RATE);
- if (sc != RTEMS_SUCCESSFUL) {
+ sc = rtems_termios_set_initial_baud( tty, MY_DRIVER_BAUD_RATE );
+ if ( sc != RTEMS_SUCCESSFUL ) {
/* Not a valid Termios baud */
}
/*
* Alternatively you can set the best baud.
*/
- rtems_termios_set_best_baud(term, MY_DRIVER_BAUD_RATE);
+ rtems_termios_set_best_baud( term, MY_DRIVER_BAUD_RATE );
/*
* To propagate the initial Termios attributes to the device use
* this.
*/
- ok = my_driver_set_attributes(base, term);
- if (!ok) {
+ ok = my_driver_set_attributes( base, term );
+ if ( !ok ) {
/* This is bad */
}
@@ -499,14 +386,10 @@ During the first open of the device Termios will call the
return true;
}
-Closing a Serial Device
------------------------
-
-The ``console_close()`` provided by :file:`console-termios.c` is invoked when
-the serial device is to be closed. This entry point corresponds to the device
-driver close entry point.
+Last Close
+==========
-Termios will call the ``my_driver_last_close()`` handler if the last close
+Termios will call the :c:func:`my_driver_last_close` handler if the last close
happens on the device.
.. code-block:: c
@@ -517,44 +400,21 @@ happens on the device.
rtems_libio_open_close_args_t *args
)
{
- my_driver_context *ctx = (my_driver_context *) base;
+ my_driver_context *ctx;
+
+ ctx = (my_driver_context *) base;
/*
* The driver may do some cleanup here.
- */
+ */
}
-Reading Characters from a Serial Device
----------------------------------------
-
-The ``console_read()`` provided by :file:`console-termios.c` is invoked when
-the serial device is to be read from. This entry point corresponds to the
-device driver read entry point.
-
-Writing Characters to a Serial Device
--------------------------------------
-
-The ``console_write()`` provided by :file:`console-termios.c` is invoked when
-the serial device is to be written to. This entry point corresponds to the
-device driver write entry point.
-
-Changing Serial Line Parameters
--------------------------------
+Set Attributes
+==============
-The ``console_control()`` provided by :file:`console-termios.c` is invoked when
-the line parameters for a particular serial device are to be changed. This
-entry point corresponds to the device driver IO control entry point.
-
-The application writer is able to control the serial line configuration with
-Termios calls (such as the ``ioctl()`` command, see the Termios documentation
-for more details). If the driver is to support dynamic configuration, then it
-must have the ``console_control()`` piece of code. Basically ``ioctl()``
-commands call ``console_control()`` with the serial line configuration in a
-Termios defined data structure.
-
-The driver is responsible for reinitializing the device with the correct
-settings. For this purpose Termios calls the ``my_driver_set_attributes()``
-handler.
+Termios will call the :c:func:`my_driver_set_attributes` handler if a serial
+line configuration parameter changed, e.g. baud, character size, number of stop
+bits, parity, etc.
.. code-block:: c
@@ -563,7 +423,9 @@ handler.
const struct termios *term
)
{
- my_driver_context *ctx = (my_driver_context *) base;
+ my_driver_context *ctx;
+
+ ctx = (my_driver_context *) base;
/*
* Inspect the termios data structure and configure the device
@@ -571,9 +433,111 @@ handler.
* parts of the structure that specify hardware setting for the
* communications channel such as baud, character size, etc.
*/
+
/*
* Return true to indicate a successful set attributes, and false
* otherwise.
*/
return true;
}
+
+IO Control
+==========
+
+Optionally, the :c:func:`my_driver_ioctl()` routine may be provided for
+arbitrary device-specific functions.
+
+.. code-block:: c
+
+ static int my_driver_ioctl(
+ rtems_termios_device_context *base,
+ ioctl_command_t request,
+ void *buffer
+ )
+ {
+ my_driver_context *ctx;
+
+ ctx = (my_driver_context *) base;
+
+ switch ( request ) {
+ case MY_DRIVER_DO_XYZ:
+ my_driver_do_xyz(ctx, buffer);
+ break;
+ default:
+ rtems_set_errno_and_return_minus_one( EINVAL );
+ }
+
+ return 0;
+ }
+
+Flow Control
+============
+
+You can also provide handler for remote transmission control. This is not
+covered in this manual.
+
+General Initialization
+======================
+
+The BSP-specific driver initialization is called once during the RTEMS
+initialization process.
+
+The :c:func:`console_initialize()` function may look like this:
+
+.. code-block:: c
+
+ #include <my-driver.h>
+
+ #include <rtems/console.h>
+
+ #include <bsp.h>
+ #include <bsp/fatal.h>
+
+ static my_driver_context driver_context_table[] = {
+ { /* Some values for device 0 */ },
+ { /* Some values for device 1 */ }
+ };
+
+ rtems_device_driver console_initialize(
+ rtems_device_major_number major,
+ rtems_device_minor_number minor,
+ void *arg
+ )
+ {
+ const rtems_termios_device_handler *handler;
+ rtems_status_code sc;
+ size_t i;
+
+ #ifdef SOME_BSP_USE_INTERRUPTS
+ handler = &my_driver_handler_interrupt;
+ #else
+ handler = &my_driver_handler_polled;
+ #endif
+
+ /*
+ * Initialize the Termios infrastructure. If Termios has already
+ * been initialized by another device driver, then this call will
+ * have no effect.
+ */
+ rtems_termios_initialize();
+
+ /* Initialize each device */
+ for ( i = 0; i < RTEMS_ARRAY_SIZE( driver_context_table ) ; ++i ) {
+ my_driver_context *ctx;
+
+ ctx = &driver_context_table[ i ];
+
+ /*
+ * Install this device in the file system and Termios. In order
+ * to use the console (i.e. being able to do printf, scanf etc.
+ * on stdin, stdout and stderr), one device must be registered as
+ * "/dev/console" (CONSOLE_DEVICE_NAME).
+ */
+ sc = rtems_termios_device_install( ctx->device_name, handler, NULL, ctx );
+ if ( sc != RTEMS_SUCCESSFUL ) {
+ bsp_fatal( SOME_BSP_FATAL_CONSOLE_DEVICE_INSTALL );
+ }
+ }
+
+ return RTEMS_SUCCESSFUL;
+ }