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/* irq.h
 *
 *  This include file describe the data structure and the functions implemented
 *  by rtems to write interrupt handlers.
 *
 * Copyright (c) 2000 Canon Research Centre France SA.
 * Emmanuel Raguet, mailto:raguet@crf.canon.fr
 *
 *  The license and distribution terms for this file may be
 *  found in found in the file LICENSE in this distribution or at
 *  http://www.OARcorp.com/rtems/license.html.
 *
 */
 
#ifndef _IRQ_H_
#define _IRQ_H_
 
#ifdef __cplusplus
extern "C" {
#endif
 
/*
 * Include some preprocessor value also used by assember code
 */
 
#include <rtems.h>
 
extern void default_int_handler();
/*-------------------------------------------------------------------------+
| Constants
+--------------------------------------------------------------------------*/
 
  /* enum of the possible interrupt sources */
typedef enum {
  BSP_INT_1 = 0,
  BSP_INT_2 = 1,
  BSP_UART  = 2,
  BSP_MAX_INT   = 3
} rtems_irq_symbolic_name;
 
  /* define that can be useful (the values are just examples) */
#define INTMASK		 0x01  
#define VECTOR_TABLE	 0x00
 
/*
 * Type definition for RTEMS managed interrupts
 */
typedef unsigned char  rtems_irq_level;
typedef unsigned char  rtems_irq_trigger;
 
struct 	__rtems_irq_connect_data__;	/* forward declaratiuon */
 
typedef void (*rtems_irq_hdl)		(void);
typedef void (*rtems_irq_enable)	(const struct __rtems_irq_connect_data__*);
typedef void (*rtems_irq_disable)	(const struct __rtems_irq_connect_data__*);
typedef int  (*rtems_irq_is_enabled)	(const struct __rtems_irq_connect_data__*);
 
typedef struct __rtems_irq_connect_data__ {
  /*
   * IRQ line
   */
  rtems_irq_symbolic_name 	name;
  /*
   * handler. See comment on handler properties below in function prototype.
   */
  rtems_irq_hdl	   		hdl;
  /*
   * function for enabling interrupts at device level (ONLY!).
   * The BSP code will automatically enable it at i8259s level.
   * RATIONALE : anyway such code has to exist in current driver code.
   * It is usually called immediately AFTER connecting the interrupt handler.
   * RTEMS may well need such a function when restoring normal interrupt
   * processing after a debug session.
   * 
   */
    rtems_irq_enable		on;	
  /*
   * function for disabling interrupts at device level (ONLY!).
   * The code will disable it at i8259s level. RATIONALE : anyway
   * such code has to exist for clean shutdown. It is usually called
   * BEFORE disconnecting the interrupt. RTEMS may well need such
   * a function when disabling normal interrupt processing for
   * a debug session. May well be a NOP function.
   */
  rtems_irq_disable		off;
  /*
   * function enabling to know what interrupt may currently occur
   * if someone manipulates the i8259s interrupt mask without care...
   */
    rtems_irq_is_enabled	isOn;
  /*
   * priority level at the vplus level
   */
  rtems_irq_level		irqLevel;
  /*
   * Trigger way : Rising or falling edge or High or low level
   */
  rtems_irq_trigger		irqTrigger;
} rtems_irq_connect_data;
 
/*-------------------------------------------------------------------------+
| Function Prototypes.
+--------------------------------------------------------------------------*/
/*
 * ------------------------ RTEMS Single Irq Handler Mngt Routines ----------------
 */
 
/*
 * function to initialize the interrupt for a specific BSP
 */
void BSP_rtems_irq_mngt_init();
 
 
/*
 * function to connect a particular irq handler. This hanlder will NOT be called
 * directly as the result of the corresponding interrupt. Instead, a RTEMS
 * irq prologue will be called that will :
 *
 *	1) save the C scratch registers,
 *	2) switch to a interrupt stack if the interrupt is not nested,
 *	3) store the current i8259s' interrupt masks
 *	4) modify them to disable the current interrupt at 8259 level (and may
 *	be others depending on software priorities)
 *	5) aknowledge the i8259s',
 *	6) demask the processor,
 *	7) call the application handler
 *
 * As a result the hdl function provided
 *
 *	a) can perfectly be written is C,
 * 	b) may also well directly call the part of the RTEMS API that can be used
 *	from interrupt level,
 *	c) It only responsible for handling the jobs that need to be done at
 *	the device level including (aknowledging/re-enabling the interrupt at device,
 *	level, getting the data,...)
 *
 *	When returning from the function, the following will be performed by
 *	the RTEMS irq epilogue :
 *
 *	1) masks the interrupts again,
 *	2) restore the original i8259s' interrupt masks
 *	3) switch back on the orinal stack if needed,
 *	4) perform rescheduling when necessary,
 *	5) restore the C scratch registers...
 *	6) restore initial execution flow
 * 
 */
 
int BSP_install_rtems_irq_handler   	(const rtems_irq_connect_data*);
/*
 * function to get the current RTEMS irq handler for ptr->name. It enables to
 * define hanlder chain...
 */
int BSP_get_current_rtems_irq_handler	(rtems_irq_connect_data* ptr);
/*
 * function to get disconnect the RTEMS irq handler for ptr->name.
 * This function checks that the value given is the current one for safety reason.
 * The user can use the previous function to get it.
 */
int BSP_remove_rtems_irq_handler    	(const rtems_irq_connect_data*);
 
 
#ifdef __cplusplus
}
#endif
 
#endif /* _IRQ_H_ */
/* end of include file */