/**
 * @file
 *
 * @ingroup bsp_interrupt
 *
 * @brief Source file for generic BSP interrupt support.
 */

/*
 * Based on concepts of Pavel Pisa, Till Straumann and Eric Valette. 
 *
 * Copyright (c) 2008
 * Embedded Brains GmbH
 * Obere Lagerstr. 30
 * D-82178 Puchheim
 * Germany
 * rtems@embedded-brains.de
 *
 * The license and distribution terms for this file may be found in the file
 * LICENSE in this distribution or at http://www.rtems.com/license/LICENSE.
 */

#include <bsp/irq-generic.h>

#ifdef BSP_INTERRUPT_USE_INDEX_TABLE
bsp_interrupt_handler_index_type bsp_interrupt_handler_index_table [BSP_INTERRUPT_VECTOR_NUMBER];
#endif /* BSP_INTERRUPT_USE_INDEX_TABLE */

bsp_interrupt_handler_entry bsp_interrupt_handler_table [BSP_INTERRUPT_HANDLER_TABLE_SIZE] = {
	[0 ... BSP_INTERRUPT_HANDLER_TABLE_SIZE - 1] = {
		.handler = bsp_interrupt_handler_empty,
		.arg = NULL,
		.info = NULL,
		.next = NULL
	}
};

/* The last entry indicates if everything is initialized */
static uint8_t bsp_interrupt_handler_unique_table [(BSP_INTERRUPT_HANDLER_TABLE_SIZE + 7 + 1) / 8];

static rtems_id bsp_interrupt_mutex = RTEMS_ID_NONE;

static inline bool bsp_interrupt_is_handler_unique( rtems_vector_number index)
{
	rtems_vector_number i = index / 8;
	rtems_vector_number s = index % 8;
	return (bsp_interrupt_handler_unique_table [i] >> s) & 0x1;
}

static inline void bsp_interrupt_set_handler_unique( rtems_vector_number index, bool unique)
{
	rtems_vector_number i = index / 8;
	rtems_vector_number s = index % 8;
	if (unique) {
		bsp_interrupt_handler_unique_table [i] |= (uint8_t) (0x1U << s);
	} else {
		bsp_interrupt_handler_unique_table [i] &= (uint8_t) ~(0x1U << s);
	}
}

static inline bool bsp_interrupt_is_initialized(void)
{
	return bsp_interrupt_is_handler_unique( BSP_INTERRUPT_HANDLER_TABLE_SIZE);
}

static inline void bsp_interrupt_set_initialized(void)
{
	bsp_interrupt_set_handler_unique( BSP_INTERRUPT_HANDLER_TABLE_SIZE, true);
}

void bsp_interrupt_handler_empty( rtems_vector_number vector, void *arg)
{
	/* Do nothing */
}

static inline void bsp_interrupt_clear_handler_entry( bsp_interrupt_handler_entry *e)
{
	e->handler = bsp_interrupt_handler_empty;
	e->arg = NULL;
	e->info = NULL;
	e->next = NULL;
}

static inline bool bsp_interrupt_allocate_handler_index( rtems_vector_number vector, rtems_vector_number *index)
{
#ifdef BSP_INTERRUPT_USE_INDEX_TABLE
	rtems_vector_number i = 0;

	/* The first entry will remain empty */
	for (i = 1; i < BSP_INTERRUPT_HANDLER_TABLE_SIZE; ++i) {
		if (bsp_interrupt_is_empty_handler_entry( &bsp_interrupt_handler_table [i])) {
			*index = i;
			return 1;
		}
	}

	return 0;
#else /* BSP_INTERRUPT_USE_INDEX_TABLE */
	*index = vector;
	return 1;
#endif /* BSP_INTERRUPT_USE_INDEX_TABLE */
}

static bsp_interrupt_handler_entry *bsp_interrupt_allocate_handler_entry()
{
#ifdef BSP_INTERRUPT_NO_HEAP_USAGE
	rtems_vector_number index = 0;
	if (bsp_interrupt_allocate_handler_index( 0, &index)) {
		return &bsp_interrupt_handler_table [index];
	} else {
		return NULL;
	}
#else /* BSP_INTERRUPT_NO_HEAP_USAGE */
	return malloc( sizeof( bsp_interrupt_handler_entry));
#endif /* BSP_INTERRUPT_NO_HEAP_USAGE */
}

static void bsp_interrupt_free_handler_entry( bsp_interrupt_handler_entry *e)
{
#ifdef BSP_INTERRUPT_NO_HEAP_USAGE
	bsp_interrupt_clear_handler_entry( e);
#else /* BSP_INTERRUPT_NO_HEAP_USAGE */
	free( e);
#endif /* BSP_INTERRUPT_NO_HEAP_USAGE */
}

static rtems_status_code bsp_interrupt_lock()
{
	rtems_status_code sc = RTEMS_SUCCESSFUL;
	if (_System_state_Is_up( _System_state_Get())) {
		if (bsp_interrupt_mutex == RTEMS_ID_NONE) {
			rtems_id mutex = RTEMS_ID_NONE;
			rtems_interrupt_level level;

			/* Create a mutex */
			sc = rtems_semaphore_create (
				rtems_build_name( 'I', 'N', 'T', 'R'),
				1,
				RTEMS_SIMPLE_BINARY_SEMAPHORE | RTEMS_INHERIT_PRIORITY | RTEMS_PRIORITY,
				RTEMS_NO_PRIORITY,
				&mutex
			);
			if (sc != RTEMS_SUCCESSFUL) {
				return sc;
			}

			/* Assign the mutex */
			rtems_interrupt_disable( level);
			if (bsp_interrupt_mutex == RTEMS_ID_NONE) {
				/* Nobody else assigned the mutex in the meantime */

				bsp_interrupt_mutex = mutex;
				rtems_interrupt_enable( level);
			} else {
				/* Somebody else won */

				rtems_interrupt_enable( level);
				sc = rtems_semaphore_delete( mutex);
				if (sc != RTEMS_SUCCESSFUL) {
					return sc;
				}
			}
		}
		return rtems_semaphore_obtain( bsp_interrupt_mutex, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
	} else {
		return RTEMS_SUCCESSFUL;
	}
}

static rtems_status_code bsp_interrupt_unlock()
{
	if (bsp_interrupt_mutex != RTEMS_ID_NONE) {
		return rtems_semaphore_release( bsp_interrupt_mutex);
	} else {
		return RTEMS_SUCCESSFUL;
	}
}

/**
 * @brief Initialize BSP interrupt support.
 *
 * You must call this function before you can install, remove and dispatch
 * interrupt handlers.  The BSP specific bsp_interrupt_facility_initialize()
 * function will be called after all internals are initialized.  Initialization
 * is complete if everything was successful.
 */
rtems_status_code bsp_interrupt_initialize()
{
	rtems_status_code sc = RTEMS_SUCCESSFUL;
	rtems_vector_number index = 0;

	/* Lock */
	sc = bsp_interrupt_lock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	/* Check if already initialized */
	if (bsp_interrupt_is_initialized()) {
		bsp_interrupt_unlock();
		return RTEMS_INTERNAL_ERROR;
	}

	/* BSP specific initialization */
	sc = bsp_interrupt_facility_initialize();
	if (sc != RTEMS_SUCCESSFUL) {
		bsp_interrupt_unlock();
		return sc;
	}

	/* Now we are initialized */
	bsp_interrupt_set_initialized();

	/* Unlock */
	sc = bsp_interrupt_unlock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	return RTEMS_SUCCESSFUL;
}

/**
 * @brief Installs an interrupt handler.
 *
 * @ingroup bsp_interrupt
 *
 * @return In addition to the standard status codes this function returns:
 * - If the BSP interrupt support is not initialized RTEMS_INTERNAL_ERROR will
 * be returned.
 * - If not enough memory for a new handler is available RTEMS_NO_MEMORY will
 * be returned
 *
 * @see rtems_interrupt_handler_install()
 */
static rtems_status_code bsp_interrupt_handler_install( rtems_vector_number vector, const char *info, rtems_option options, rtems_interrupt_handler handler, void *arg)
{
	rtems_status_code sc = RTEMS_SUCCESSFUL;
	rtems_interrupt_level level;
	rtems_vector_number index = 0;
	bsp_interrupt_handler_entry *head = NULL;
	bsp_interrupt_handler_entry *tail = NULL;
	bsp_interrupt_handler_entry *current = NULL;
	bsp_interrupt_handler_entry *match = NULL;
	bool enable_vector = false;

	/* Check parameters and system state */
	if (!bsp_interrupt_is_initialized()) {
		return RTEMS_INTERNAL_ERROR;
	} else if (!bsp_interrupt_is_valid_vector( vector)) {
		return RTEMS_INVALID_NUMBER;
	} else if (handler == NULL) {
		return RTEMS_INVALID_ADDRESS;
	} else if (rtems_interrupt_is_in_progress()) {
		return RTEMS_CALLED_FROM_ISR;
	}

	/* Lock */
	sc = bsp_interrupt_lock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	/* Get handler table index */
	index = bsp_interrupt_handler_index( vector);

	/* Get head entry of the handler list for current vector */
	head = &bsp_interrupt_handler_table [index];

	if (bsp_interrupt_is_empty_handler_entry( head)) {
		/*
		 * No real handler installed yet.  So allocate a new index in
		 * the handler table and fill the entry with life.
		 */
		if (bsp_interrupt_allocate_handler_index( vector, &index)) {
			rtems_interrupt_disable( level);
			bsp_interrupt_handler_table [index].handler = handler;
			bsp_interrupt_handler_table [index].arg = arg;
#ifdef BSP_INTERRUPT_USE_INDEX_TABLE
			bsp_interrupt_handler_index_table [vector] = index;
#endif /* BSP_INTERRUPT_USE_INDEX_TABLE */
			rtems_interrupt_enable( level);
			bsp_interrupt_handler_table [index].info = info;
		} else {
			/* Handler table is full */
			bsp_interrupt_unlock();
			return RTEMS_NO_MEMORY;
		}

		/* This is the first handler so enable the vector later */
		enable_vector = true;
	} else {
		/* Ensure that a unique handler remains unique */
		if (RTEMS_INTERRUPT_IS_UNIQUE( options) || bsp_interrupt_is_handler_unique( index)) {
			/*
			 * Tried to install a unique handler on a not empty
			 * list or there is already a unique handler installed.
			 */
			bsp_interrupt_unlock();
			return RTEMS_RESOURCE_IN_USE;
		}

		/*
		 * Search for the list tail and check if the handler is already
		 * installed.
		 */
		current = head;
		do {
			if (current->handler == handler && current->arg == arg) {
				match = current;
			}
			tail = current;
			current = current->next;
		} while (current != NULL);

		/* Ensure the handler is not already installed */
		if (match != NULL) {
			/* The handler is already installed */
			bsp_interrupt_unlock();
			return RTEMS_TOO_MANY;
		}

		/* Allocate a new entry */
		current = bsp_interrupt_allocate_handler_entry();
		if (current == NULL) {
			/* Not enough memory */
			bsp_interrupt_unlock();
			return RTEMS_NO_MEMORY;
		}

		/* Set entry */
		current->handler = handler;
		current->arg = arg;
		current->info = info;
		current->next = NULL;

		/* Link to list tail */
		rtems_interrupt_disable( level);
		tail->next = current;
		rtems_interrupt_enable( level);
	}

	/* Make the handler unique if necessary */
	bsp_interrupt_set_handler_unique( index, RTEMS_INTERRUPT_IS_UNIQUE( options));

	/* Enable the vector if necessary */
	if (enable_vector) {
		sc = bsp_interrupt_vector_enable( vector);
		if (sc != RTEMS_SUCCESSFUL) {
			bsp_interrupt_unlock();
			return sc;
		}
	}

	/* Unlock */
	sc = bsp_interrupt_unlock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	return RTEMS_SUCCESSFUL;
}

/**
 * @brief Removes an interrupt handler.
 *
 * @ingroup bsp_interrupt
 *
 * @return In addition to the standard status codes this function returns
 * RTEMS_INTERNAL_ERROR if the BSP interrupt support is not initialized.
 *
 * @see rtems_interrupt_handler_remove().
 */
static rtems_status_code bsp_interrupt_handler_remove( rtems_vector_number vector, rtems_interrupt_handler handler, void *arg)
{
	rtems_status_code sc = RTEMS_SUCCESSFUL;
	rtems_interrupt_level level;
	rtems_vector_number index = 0;
	bsp_interrupt_handler_entry *head = NULL;
	bsp_interrupt_handler_entry *current = NULL;
	bsp_interrupt_handler_entry *previous = NULL;
	bsp_interrupt_handler_entry *match = NULL;

	/* Check parameters and system state */
	if (!bsp_interrupt_is_initialized()) {
		return RTEMS_INTERNAL_ERROR;
	} else if (!bsp_interrupt_is_valid_vector( vector)) {
		return RTEMS_INVALID_NUMBER;
	} else if (handler == NULL) {
		return RTEMS_INVALID_ADDRESS;
	} else if (rtems_interrupt_is_in_progress()) {
		return RTEMS_CALLED_FROM_ISR;
	}

	/* Lock */
	sc = bsp_interrupt_lock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	/* Get handler table index */
	index = bsp_interrupt_handler_index( vector);

	/* Get head entry of the handler list for current vector */
	head = &bsp_interrupt_handler_table [index];

	/* Search for a matching entry */
	current = head;
	do {
		if (current->handler == handler && current->arg == arg) {
			match = current;
			break;
		}
		previous = current;
		current = current->next;
	} while (current != NULL);

	/* Remove the matching entry */
	if (match != NULL) {
		if (match->next != NULL) {
			/*
			 * The match has a successor.  A successor is always
			 * allocated.  So replace the match with its successor
			 * and free the successor entry.
			 */
			current = match->next;

			rtems_interrupt_disable( level);
			*match = *current;
			rtems_interrupt_enable( level);

			bsp_interrupt_free_handler_entry( current);
		} else if (match == head) {
			/*
			 * The match is the list head and has no successor.
			 * The list head is stored in a static table so clear
			 * this entry.  Since now the list is empty disable the
			 * vector.
			 */

			/* Disable the vector */
			sc = bsp_interrupt_vector_disable( vector);

			/* Clear entry */
			rtems_interrupt_disable( level);
			bsp_interrupt_clear_handler_entry( head);
#ifdef BSP_INTERRUPT_USE_INDEX_TABLE
			bsp_interrupt_handler_index_table [vector] = 0;
#endif /* BSP_INTERRUPT_USE_INDEX_TABLE */
			rtems_interrupt_enable( level);

			/* Allow shared handlers */
			bsp_interrupt_set_handler_unique( index, false);

			/* Check status code */
			if (sc != RTEMS_SUCCESSFUL) {
				bsp_interrupt_unlock();
				return sc;
			}
		} else {
			/*
			 * The match is the list tail and has a predecessor.
			 * So terminate the predecessor and free the match.
			 */
			rtems_interrupt_disable( level);
			previous->next = NULL;
			rtems_interrupt_enable( level);

			bsp_interrupt_free_handler_entry( match);
		}
	} else {
		/* No matching entry found */
		bsp_interrupt_unlock();
		return RTEMS_UNSATISFIED;
	}

	/* Unlock */
	sc = bsp_interrupt_unlock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	return RTEMS_SUCCESSFUL;
}

/**
 * @brief Iterates over all installed interrupt handler of a vector.
 *
 * @ingroup bsp_interrupt
 *
 * @return In addition to the standard status codes this function returns
 * RTEMS_INTERNAL_ERROR if the BSP interrupt support is not initialized.
 *
 * @see rtems_interrupt_handler_iterate().
 */
static rtems_status_code bsp_interrupt_handler_iterate( rtems_vector_number vector, rtems_interrupt_per_handler_routine routine, void *arg)
{
	rtems_status_code sc = RTEMS_SUCCESSFUL;
	bsp_interrupt_handler_entry *current = NULL;
	rtems_option options = 0;
	rtems_vector_number index = 0;

	/* Check parameters and system state */
	if (!bsp_interrupt_is_initialized()) {
		return RTEMS_INTERNAL_ERROR;
	} else if (!bsp_interrupt_is_valid_vector( vector)) {
		return RTEMS_INVALID_NUMBER;
	} else if (rtems_interrupt_is_in_progress()) {
		return RTEMS_CALLED_FROM_ISR;
	}

	/* Lock */
	sc = bsp_interrupt_lock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	/* Interate */
	index = bsp_interrupt_handler_index( vector);
	current = &bsp_interrupt_handler_table [index];
	if (!bsp_interrupt_is_empty_handler_entry( current)) {
		do {
			options = bsp_interrupt_is_handler_unique( index) ? RTEMS_INTERRUPT_UNIQUE : RTEMS_INTERRUPT_SHARED;
			routine( arg, current->info, options, current->handler, current->arg);
			current = current->next;
		} while (current != NULL);
	}

	/* Unlock */
	sc = bsp_interrupt_unlock();
	if (sc != RTEMS_SUCCESSFUL) {
		return sc;
	}

	return RTEMS_SUCCESSFUL;
}

rtems_status_code rtems_interrupt_handler_install( rtems_vector_number vector, const char *info, rtems_option options, rtems_interrupt_handler handler, void *arg)
{
	return bsp_interrupt_handler_install( vector, info, options, handler, arg);
}

rtems_status_code rtems_interrupt_handler_remove( rtems_vector_number vector, rtems_interrupt_handler handler, void *arg)
{
	return bsp_interrupt_handler_remove( vector, handler, arg);
}

rtems_status_code rtems_interrupt_handler_iterate( rtems_vector_number vector, rtems_interrupt_per_handler_routine routine, void *arg)
{
	return bsp_interrupt_handler_iterate( vector, routine, arg);
}