/*
 * Copyright 2002-2009, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */


#include <int.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <arch/debug_console.h>
#include <arch/int.h>
#include <boot/kernel_args.h>
#include <elf.h>
#include <util/kqueue.h>
#include <smp.h>

#include "kernel_debug_config.h"


//#define TRACE_INT
#ifdef TRACE_INT
#	define TRACE(x) dprintf x
#else
#	define TRACE(x) ;
#endif


struct io_handler {
	struct io_handler	*next;
	interrupt_handler	func;
	void				*data;
	bool				use_enable_counter;
	bool				no_handled_info;
#if DEBUG_INTERRUPTS
	int64				handled_count;
#endif
};

struct io_vector {
	struct io_handler	*handler_list;
	spinlock			vector_lock;
	int32				enable_count;
	bool				no_lock_vector;
#if DEBUG_INTERRUPTS
	int64				handled_count;
	int64				unhandled_count;
	int					trigger_count;
	int					ignored_count;
#endif
};

static struct io_vector sVectors[NUM_IO_VECTORS];


#if DEBUG_INTERRUPTS
static int
dump_int_statistics(int argc, char **argv)
{
	int i;
	for (i = 0; i < NUM_IO_VECTORS; i++) {
		struct io_handler *io;

		if (!B_SPINLOCK_IS_LOCKED(&sVectors[i].vector_lock)
			&& sVectors[i].enable_count == 0
			&& sVectors[i].handled_count == 0
			&& sVectors[i].unhandled_count == 0
			&& sVectors[i].handler_list == NULL)
			continue;

		kprintf("int %3d, enabled %ld, handled %8lld, unhandled %8lld%s%s\n",
			i, sVectors[i].enable_count, sVectors[i].handled_count,
			sVectors[i].unhandled_count,
			B_SPINLOCK_IS_LOCKED(&sVectors[i].vector_lock) ? ", ACTIVE" : "",
			sVectors[i].handler_list == NULL ? ", no handler" : "");

		for (io = sVectors[i].handler_list; io != NULL; io = io->next) {
			const char *symbol, *imageName;
			bool exactMatch;

			status_t error = elf_debug_lookup_symbol_address((addr_t)io->func,
				NULL, &symbol, &imageName, &exactMatch);
			if (error == B_OK && exactMatch) {
				if (strchr(imageName, '/') != NULL)
					imageName = strrchr(imageName, '/') + 1;

				int length = 4 + strlen(imageName);
				kprintf("   %s:%-*s (%p)", imageName, 45 - length, symbol,
					io->func);
			} else
				kprintf("\t\t\t\t\t   func %p", io->func);

			kprintf(", data %p, handled ", io->data);
			if (io->no_handled_info)
				kprintf("<unknown>\n");
			else
				kprintf("%8lld\n", io->handled_count);
		}

		kprintf("\n");
	}
	return 0;
}
#endif


//	#pragma mark - private kernel API


bool
interrupts_enabled(void)
{
	return arch_int_are_interrupts_enabled();
}


status_t
int_init(kernel_args *args)
{
	TRACE(("init_int_handlers: entry\n"));

	return arch_int_init(args);
}


status_t
int_init_post_vm(kernel_args *args)
{
	int i;

	/* initialize the vector list */
	for (i = 0; i < NUM_IO_VECTORS; i++) {
		B_INITIALIZE_SPINLOCK(&sVectors[i].vector_lock);
		sVectors[i].enable_count = 0;
		sVectors[i].no_lock_vector = false;
#if DEBUG_INTERRUPTS
		sVectors[i].handled_count = 0;
		sVectors[i].unhandled_count = 0;
		sVectors[i].trigger_count = 0;
		sVectors[i].ignored_count = 0;
#endif
		sVectors[i].handler_list = NULL;
	}

#if DEBUG_INTERRUPTS
	add_debugger_command("ints", &dump_int_statistics,
		"list interrupt statistics");
#endif

	return arch_int_init_post_vm(args);
}


status_t
int_init_post_device_manager(kernel_args *args)
{
	arch_debug_install_interrupt_handlers();

	return arch_int_init_post_device_manager(args);
}


/*!	Actually process an interrupt via the handlers registered for that
	vector (IRQ).
*/
int
int_io_interrupt_handler(int vector, bool levelTriggered)
{
	int status = B_UNHANDLED_INTERRUPT;
	struct io_handler *io;
	bool handled = false;

	if (!sVectors[vector].no_lock_vector)
		acquire_spinlock(&sVectors[vector].vector_lock);

#if !DEBUG_INTERRUPTS
	// The list can be empty at this place
	if (sVectors[vector].handler_list == NULL) {
		dprintf("unhandled io interrupt %d\n", vector);
		if (!sVectors[vector].no_lock_vector)
			release_spinlock(&sVectors[vector].vector_lock);
		return B_UNHANDLED_INTERRUPT;
	}
#endif

	// For level-triggered interrupts, we actually handle the return
	// value (ie. B_HANDLED_INTERRUPT) to decide wether or not we
	// want to call another interrupt handler.
	// For edge-triggered interrupts, however, we always need to call
	// all handlers, as multiple interrupts cannot be identified. We
	// still make sure the return code of this function will issue
	// whatever the driver thought would be useful.

	for (io = sVectors[vector].handler_list; io != NULL; io = io->next) {
		status = io->func(io->data);

#if DEBUG_INTERRUPTS
		if (status != B_UNHANDLED_INTERRUPT)
			io->handled_count++;
#endif
		if (levelTriggered && status != B_UNHANDLED_INTERRUPT)
			break;

		if (status == B_HANDLED_INTERRUPT || status == B_INVOKE_SCHEDULER)
			handled = true;
	}

#if DEBUG_INTERRUPTS
	sVectors[vector].trigger_count++;
	if (status != B_UNHANDLED_INTERRUPT || handled) {
		sVectors[vector].handled_count++;
	} else {
		sVectors[vector].unhandled_count++;
		sVectors[vector].ignored_count++;
	}

	if (sVectors[vector].trigger_count > 10000) {
		if (sVectors[vector].ignored_count > 9900) {
			struct io_handler *last = sVectors[vector].handler_list;
			while (last && last->next)
				last = last->next;

			if (last != NULL && last->no_handled_info) {
				// we have an interrupt handler installed that does not
				// know whether or not it has actually handled the interrupt,
				// so this unhandled count is inaccurate and we can't just
				// disable
			} else {
				if (sVectors[vector].handler_list == NULL
					|| sVectors[vector].handler_list->next == NULL) {
					// this interrupt vector is not shared, disable it
					sVectors[vector].enable_count = -100;
					arch_int_disable_io_interrupt(vector);
					dprintf("Disabling unhandled io interrupt %d\n", vector);
				} else {
					// this is a shared interrupt vector, we cannot just disable it
					dprintf("More than 99%% interrupts of vector %d are unhandled\n",
						vector);
				}
			}
		}

		sVectors[vector].trigger_count = 0;
		sVectors[vector].ignored_count = 0;
	}
#endif

	if (!sVectors[vector].no_lock_vector)
		release_spinlock(&sVectors[vector].vector_lock);

	if (levelTriggered)
		return status;

	// edge triggered return value

	if (handled)
		return B_HANDLED_INTERRUPT;

	return B_UNHANDLED_INTERRUPT;
}


//	#pragma mark - public API


#undef disable_interrupts
#undef restore_interrupts


cpu_status
disable_interrupts(void)
{
	return arch_int_disable_interrupts();
}


void
restore_interrupts(cpu_status status)
{
	arch_int_restore_interrupts(status);
}


/*!	Install a handler to be called when an interrupt is triggered
	for the given interrupt number with \a data as the argument.
*/
status_t
install_io_interrupt_handler(long vector, interrupt_handler handler, void *data,
	ulong flags)
{
	struct io_handler *io = NULL;
	cpu_status state;

	if (vector < 0 || vector >= NUM_IO_VECTORS)
		return B_BAD_VALUE;

	io = (struct io_handler *)malloc(sizeof(struct io_handler));
	if (io == NULL)
		return B_NO_MEMORY;

	arch_debug_remove_interrupt_handler(vector);
		// There might be a temporary debug interrupt installed on this
		// vector that should be removed now.

	io->func = handler;
	io->data = data;
	io->use_enable_counter = (flags & B_NO_ENABLE_COUNTER) == 0;
	io->no_handled_info = (flags & B_NO_HANDLED_INFO) != 0;
#if DEBUG_INTERRUPTS
	io->handled_count = 0LL;
#endif

	// Disable the interrupts, get the spinlock for this irq only
	// and then insert the handler
	state = disable_interrupts();
	acquire_spinlock(&sVectors[vector].vector_lock);

	if ((flags & B_NO_HANDLED_INFO) != 0
		&& sVectors[vector].handler_list != NULL) {
		// The driver registering this interrupt handler doesn't know
		// whether or not it actually handled the interrupt after the
		// handler returns. This is incompatible with shared interrupts
		// as we'd potentially steal interrupts from other handlers
		// resulting in interrupt storms. Therefore we enqueue this interrupt
		// handler as the very last one, meaning all other handlers will
		// get their go at any interrupt first.
		struct io_handler *last = sVectors[vector].handler_list;
		while (last->next)
			last = last->next;

		io->next = NULL;
		last->next = io;
	} else {
		// A normal interrupt handler, just add it to the head of the list.
		io->next = sVectors[vector].handler_list;
		sVectors[vector].handler_list = io;
	}

	// If B_NO_ENABLE_COUNTER is set, we're being asked to not alter
	// whether the interrupt should be enabled or not
	if (io->use_enable_counter) {
		if (sVectors[vector].enable_count++ == 0)
			arch_int_enable_io_interrupt(vector);
	}

	// If B_NO_LOCK_VECTOR is specified this is a vector that is not supposed
	// to have multiple handlers and does not require locking of the vector
	// when entering the handler. For example this is used by internally
	// registered interrupt handlers like for handling local APIC interrupts
	// that may run concurently on multiple CPUs. Locking with a spinlock
	// would in that case defeat the purpose as it would serialize calling the
	// handlers in parallel on different CPUs.
	if (flags & B_NO_LOCK_VECTOR)
		sVectors[vector].no_lock_vector = true;

	release_spinlock(&sVectors[vector].vector_lock);
	restore_interrupts(state);

	return B_OK;
}


/*!	Remove a previously installed interrupt handler */
status_t
remove_io_interrupt_handler(long vector, interrupt_handler handler, void *data)
{
	status_t status = B_BAD_VALUE;
	struct io_handler *io = NULL;
	struct io_handler *last = NULL;
	cpu_status state;

	if (vector < 0 || vector >= NUM_IO_VECTORS)
		return B_BAD_VALUE;

	/* lock the structures down so it is not modified while we search */
	state = disable_interrupts();
	acquire_spinlock(&sVectors[vector].vector_lock);

	/* loop through the available handlers and try to find a match.
	 * We go forward through the list but this means we start with the
	 * most recently added handlers.
	 */
	for (io = sVectors[vector].handler_list; io != NULL; io = io->next) {
		/* we have to match both function and data */
		if (io->func == handler && io->data == data) {
			if (last != NULL)
				last->next = io->next;
			else
				sVectors[vector].handler_list = io->next;

			// Check if we need to disable the interrupt
			if (io->use_enable_counter && --sVectors[vector].enable_count == 0)
				arch_int_disable_io_interrupt(vector);

			status = B_OK;
			break;
		}

		last = io;
	}

	release_spinlock(&sVectors[vector].vector_lock);
	restore_interrupts(state);

	// if the handler could be found and removed, we still have to free it
	if (status == B_OK)
		free(io);

	return status;
}