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diff --git a/doc/user/intr.t b/doc/user/intr.t deleted file mode 100644 index 74fbf7af6b..0000000000 --- a/doc/user/intr.t +++ /dev/null @@ -1,426 +0,0 @@ -@c -@c COPYRIGHT (c) 1988-1998. -@c On-Line Applications Research Corporation (OAR). -@c All rights reserved. -@c -@c $Id$ -@c - -@chapter Interrupt Manager - -@section Introduction - -Any real-time executive must provide a mechanism for -quick response to externally generated interrupts to satisfy the -critical time constraints of the application. The interrupt -manager provides this mechanism for RTEMS. This manager permits -quick interrupt response times by providing the critical ability -to alter task execution which allows a task to be preempted upon -exit from an ISR. The interrupt manager includes the following -directive: - -@itemize @bullet -@item @code{@value{DIRPREFIX}interrupt_catch} - Establish an ISR -@item @code{@value{DIRPREFIX}interrupt_disable} - Disable Interrupts -@item @code{@value{DIRPREFIX}interrupt_enable} - Enable Interrupts -@item @code{@value{DIRPREFIX}interrupt_flash} - Flash Interrupt -@item @code{@value{DIRPREFIX}interrupt_is_in_progress} - Is an ISR in Progress -@end itemize - -@section Background - -@subsection Processing an Interrupt - -The interrupt manager allows the application to -connect a function to a hardware interrupt vector. When an -interrupt occurs, the processor will automatically vector to -RTEMS. RTEMS saves and restores all registers which are not -preserved by the normal @value{LANGUAGE} calling convention -for the target -processor and invokes the user's ISR. The user's ISR is -responsible for processing the interrupt, clearing the interrupt -if necessary, and device specific manipulation. - -The @code{@value{DIRPREFIX}interrupt_catch} -directive connects a procedure to -an interrupt vector. The interrupt service routine is assumed -to abide by these conventions and have a prototype similar to -the following: - -@ifset is-C -@example -rtems_isr user_isr( - rtems_vector_number vector -); -@end example -@end ifset - -@ifset is-Ada -@example -procedure User_ISR ( - vector : in RTEMS.Vector_Number -); -@end example -@end ifset - -The vector number argument is provided by RTEMS to -allow the application to identify the interrupt source. This -could be used to allow a single routine to service interrupts -from multiple instances of the same device. For example, a -single routine could service interrupts from multiple serial -ports and use the vector number to identify which port requires -servicing. - -To minimize the masking of lower or equal priority -level interrupts, the ISR should perform the minimum actions -required to service the interrupt. Other non-essential actions -should be handled by application tasks. Once the user's ISR has -completed, it returns control to the RTEMS interrupt manager -which will perform task dispatching and restore the registers -saved before the ISR was invoked. - -The RTEMS interrupt manager guarantees that proper -task scheduling and dispatching are performed at the conclusion -of an ISR. A system call made by the ISR may have readied a -task of higher priority than the interrupted task. Therefore, -when the ISR completes, the postponed dispatch processing must -be performed. No dispatch processing is performed as part of -directives which have been invoked by an ISR. - -Applications must adhere to the following rule if -proper task scheduling and dispatching is to be performed: - -@itemize @b{ } - -@item @b{The interrupt manager must be used for all ISRs which -may be interrupted by the highest priority ISR which invokes an -RTEMS directive.} - -@end itemize - - -Consider a processor which allows a numerically low -interrupt level to interrupt a numerically greater interrupt -level. In this example, if an RTEMS directive is used in a -level 4 ISR, then all ISRs which execute at levels 0 through 4 -must use the interrupt manager. - -Interrupts are nested whenever an interrupt occurs -during the execution of another ISR. RTEMS supports efficient -interrupt nesting by allowing the nested ISRs to terminate -without performing any dispatch processing. Only when the -outermost ISR terminates will the postponed dispatching occur. - -@subsection RTEMS Interrupt Levels - -Many processors support multiple interrupt levels or -priorities. The exact number of interrupt levels is processor -dependent. RTEMS internally supports 256 interrupt levels which -are mapped to the processor's interrupt levels. For specific -information on the mapping between RTEMS and the target -processor's interrupt levels, refer to the Interrupt Processing -chapter of the Applications Supplement document for a specific -target processor. - -@subsection Disabling of Interrupts by RTEMS - -During the execution of directive calls, critical -sections of code may be executed. When these sections are -encountered, RTEMS disables all maskable interrupts before the -execution of the section and restores them to the previous level -upon completion of the section. RTEMS has been optimized to -insure that interrupts are disabled for a minimum length of -time. The maximum length of time interrupts are disabled by -RTEMS is processor dependent and is detailed in the Timing -Specification chapter of the Applications Supplement document -for a specific target processor. - -Non-maskable interrupts (NMI) cannot be disabled, and -ISRs which execute at this level MUST NEVER issue RTEMS system -calls. If a directive is invoked, unpredictable results may -occur due to the inability of RTEMS to protect its critical -sections. However, ISRs that make no system calls may safely -execute as non-maskable interrupts. - -@section Operations - -@subsection Establishing an ISR - -The @code{@value{DIRPREFIX}interrupt_catch} -directive establishes an ISR for -the system. The address of the ISR and its associated CPU -vector number are specified to this directive. This directive -installs the RTEMS interrupt wrapper in the processor's -Interrupt Vector Table and the address of the user's ISR in the -RTEMS' Vector Table. This directive returns the previous -contents of the specified vector in the RTEMS' Vector Table. - -@subsection Directives Allowed from an ISR - -Using the interrupt manager insures that RTEMS knows -when a directive is being called from an ISR. The ISR may then -use system calls to synchronize itself with an application task. -The synchronization may involve messages, events or signals -being passed by the ISR to the desired task. Directives invoked -by an ISR must operate only on objects which reside on the local -node. The following is a list of RTEMS system calls that may be -made from an ISR: - -@itemize @bullet -@item Task Management - -@itemize - -@item task_get_note, task_set_note, task_suspend, task_resume -@end itemize - -@item Clock Management - -@itemize - -@item clock_get, clock_tick -@end itemize - -@item Message, Event, and Signal Management - -@itemize - -@item message_queue_send, message_queue_urgent -@item event_send -@item signal_send -@end itemize - -@item Semaphore Management - -@itemize - -@item semaphore_release -@end itemize - -@item Dual-Ported Memory Management - -@itemize - -@item port_external_to_internal, port_internal_to_external -@end itemize - -@item IO Management - -@itemize - -@item io_initialize, io_open, io_close, io_read, io_write, io_control -@end itemize - -@item Fatal Error Management - -@itemize - -@item fatal_error_occurred -@end itemize - -@item Multiprocessing - -@itemize - -@item multiprocessing_announce -@end itemize -@end itemize - -@section Directives - -This section details the interrupt 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. - -@page -@subsection INTERRUPT_CATCH - Establish an ISR - -@subheading CALLING SEQUENCE: - -@ifset is-C -@c @findex rtems_interrupt_catch -@example -rtems_status_code rtems_interrupt_catch( - rtems_isr_entry new_isr_handler, - rtems_vector_number vector, - rtems_isr_entry *old_isr_handler -); -@end example -@end ifset - -@ifset is-Ada -@example -procedure Interrupt_Catch ( - New_ISR_handler : in RTEMS.Address; - Vector : in RTEMS.Vector_Number; - Old_ISR_Handler : out RTEMS.Address; - Result : out RTEMS.Status_Codes -); -@end example -@end ifset - -@subheading DIRECTIVE STATUS CODES: -@code{@value{RPREFIX}SUCCESSFUL} - ISR established successfully@* -@code{@value{RPREFIX}INVALID_NUMBER} - illegal vector number@* -@code{@value{RPREFIX}INVALID_ADDRESS} - illegal ISR entry point or invalid old_isr_handler - -@subheading DESCRIPTION: - -This directive establishes an interrupt service -routine (ISR) for the specified interrupt vector number. The -@code{new_isr_handler} parameter specifies the entry point of the ISR. -The entry point of the previous ISR for the specified vector is -returned in @code{old_isr_handler}. - -@subheading NOTES: - -This directive will not cause the calling task to be preempted. - -@page -@subsection INTERRUPT_DISABLE - Disable Interrupts - -@subheading CALLING SEQUENCE: - -@ifset is-C -@c @findex rtems_interrupt_disable -@example -void rtems_interrupt_disable( - rtems_isr_level level -); -@end example -@end ifset - -@ifset is-Ada -@example -function Interrupt_Disable -return RTEMS.ISR_Level; -@end example -@end ifset - -@subheading DIRECTIVE STATUS CODES: - -NONE - -@subheading DESCRIPTION: - -This directive disables all maskable interrupts and returns -the previous @code{level}. A later invocation of the -@code{@value{DIRPREFIX}interrupt_enable} directive should be used to -restore the interrupt level. - -@subheading NOTES: - -This directive will not cause the calling task to be preempted. - -@ifset is-C -@b{This directive is implemented as a macro which modifies the @code{level} -parameter.} -@end ifset - -@page -@subsection INTERRUPT_ENABLE - Enable Interrupts - -@subheading CALLING SEQUENCE: - -@ifset is-C -@c @findex rtems_interrupt_enable -@example -void rtems_interrupt_enable( - rtems_isr_level level -); -@end example -@end ifset - -@ifset is-Ada -@example -procedure Interrupt_Enable ( - Level : in RTEMS.ISR_Level -); -@end example -@end ifset - -@subheading DIRECTIVE STATUS CODES: - -NONE - -@subheading DESCRIPTION: - -This directive enables maskable interrupts to the @code{level} -which was returned by a previous call to -@code{@value{DIRPREFIX}interrupt_disable}. -Immediately prior to invoking this directive, maskable interrupts should -be disabled by a call to @code{@value{DIRPREFIX}interrupt_disable} -and will be enabled when this directive returns to the caller. - -@subheading NOTES: - -This directive will not cause the calling task to be preempted. - - -@page -@subsection INTERRUPT_FLASH - Flash Interrupts - -@subheading CALLING SEQUENCE: - -@ifset is-C -@c @findex rtems_interrupt_flash -@example -void rtems_interrupt_flash( - rtems_isr_level level -); -@end example -@end ifset - -@ifset is-Ada -@example -procedure Interrupt_Flash ( - Level : in RTEMS.ISR_Level -); -@end example -@end ifset - -@subheading DIRECTIVE STATUS CODES: - -NONE - -@subheading DESCRIPTION: - -This directive temporarily enables maskable interrupts to the @code{level} -which was returned by a previous call to -@code{@value{DIRPREFIX}interrupt_disable}. -Immediately prior to invoking this directive, maskable interrupts should -be disabled by a call to @code{@value{DIRPREFIX}interrupt_disable} -and will be redisabled when this directive returns to the caller. - -@subheading NOTES: - -This directive will not cause the calling task to be preempted. - -@page -@subsection INTERRUPT_IS_IN_PROGRESS - Is an ISR in Progress - -@subheading CALLING SEQUENCE: - -@ifset is-C -@c @findex rtems_interrupt_is_in_progress -@example -rtems_boolean rtems_interrupt_is_in_progress( void ); -@end example -@end ifset - -@ifset is-Ada -@example -function Interrupt_Is_In_Progress -return RTEMS.Boolean; -@end example -@end ifset - -@subheading DIRECTIVE STATUS CODES: - -NONE - -@subheading DESCRIPTION: - -This directive returns @code{TRUE} if the processor is currently -servicing an interrupt and @code{FALSE} otherwise. A return value -of @code{TRUE} indicates that the caller is an interrupt service -routine, @b{NOT} a task. The directives available to an interrupt -service routine are restricted. - -@subheading NOTES: - -This directive will not cause the calling task to be preempted. - |