/*
 * Copyright (c) 2006 Ondrej Palkovsky
 * Copyright (c) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup genericipc
 * @{
 */

/**
 * @file
 * @brief IRQ notification framework.
 *
 * This framework allows applications to register to receive a notification
 * when interrupt is detected. The application may provide a simple 'top-half'
 * handler as part of its registration, which can perform simple operations
 * (read/write port/memory, add information to notification IPC message).
 *
 * The structure of a notification message is as follows:
 * - IMETHOD: interface and method as registered by
 *            the SYS_IRQ_REGISTER syscall
 * - ARG1: payload modified by a 'top-half' handler (scratch[1])
 * - ARG2: payload modified by a 'top-half' handler (scratch[2])
 * - ARG3: payload modified by a 'top-half' handler (scratch[3])
 * - ARG4: payload modified by a 'top-half' handler (scratch[4])
 * - ARG5: payload modified by a 'top-half' handler (scratch[5])
 * - in_phone_hash: interrupt counter (may be needed to assure correct order
 *                  in multithreaded drivers)
 *
 * Note on synchronization for ipc_irq_register(), ipc_irq_unregister(),
 * ipc_irq_cleanup() and IRQ handlers:
 *
 *   By always taking all of the uspace IRQ hash table lock, IRQ structure lock
 *   and answerbox lock, we can rule out race conditions between the
 *   registration functions and also the cleanup function. Thus the observer can
 *   either see the IRQ structure present in both the hash table and the
 *   answerbox list or absent in both. Views in which the IRQ structure would be
 *   linked in the hash table but not in the answerbox list, or vice versa, are
 *   not possible.
 *
 *   By always taking the hash table lock and the IRQ structure lock, we can
 *   rule out a scenario in which we would free up an IRQ structure, which is
 *   still referenced by, for example, an IRQ handler. The locking scheme forces
 *   us to lock the IRQ structure only after any progressing IRQs on that
 *   structure are finished. Because we hold the hash table lock, we prevent new
 *   IRQs from taking new references to the IRQ structure.
 *
 */

#include <arch.h>
#include <mm/slab.h>
#include <mm/page.h>
#include <mm/km.h>
#include <errno.h>
#include <ddi/irq.h>
#include <ipc/ipc.h>
#include <ipc/irq.h>
#include <syscall/copy.h>
#include <console/console.h>
#include <print.h>
#include <macros.h>

static void ranges_unmap(irq_pio_range_t *ranges, size_t rangecount)
{
	for (size_t i = 0; i < rangecount; i++) {
#ifdef IO_SPACE_BOUNDARY
		if ((void *) ranges[i].base >= IO_SPACE_BOUNDARY)
#endif
			km_unmap(ranges[i].base, ranges[i].size);
	}
}

static int ranges_map_and_apply(irq_pio_range_t *ranges, size_t rangecount,
    irq_cmd_t *cmds, size_t cmdcount)
{
	/* Copy the physical base addresses aside. */
	uintptr_t *pbase = malloc(rangecount * sizeof(uintptr_t), 0);
	for (size_t i = 0; i < rangecount; i++)
		pbase[i] = ranges[i].base;
	
	/* Map the PIO ranges into the kernel virtual address space. */
	for (size_t i = 0; i < rangecount; i++) {
#ifdef IO_SPACE_BOUNDARY
		if ((void *) ranges[i].base < IO_SPACE_BOUNDARY)
			continue;
#endif
		ranges[i].base = km_map(pbase[i], ranges[i].size,
		    PAGE_READ | PAGE_WRITE | PAGE_KERNEL | PAGE_NOT_CACHEABLE);
		if (!ranges[i].base) {
			ranges_unmap(ranges, i);
			free(pbase);
			return ENOMEM;
		}
	}
	
	/* Rewrite the pseudocode addresses from physical to kernel virtual. */
	for (size_t i = 0; i < cmdcount; i++) {
		uintptr_t addr;
		size_t size;
		
		/* Process only commands that use an address. */
		switch (cmds[i].cmd) {
		case CMD_PIO_READ_8:
		case CMD_PIO_WRITE_8:
		case CMD_PIO_WRITE_A_8:
			size = 1;
			break;
		case CMD_PIO_READ_16:
		case CMD_PIO_WRITE_16:
		case CMD_PIO_WRITE_A_16:
			size = 2;
			break;
		case CMD_PIO_READ_32:
		case CMD_PIO_WRITE_32:
		case CMD_PIO_WRITE_A_32:
			size = 4;
			break;
		default:
			/* Move onto the next command. */
			continue;
		}
		
		addr = (uintptr_t) cmds[i].addr;
		
		size_t j;
		for (j = 0; j < rangecount; j++) {
			/* Find the matching range. */
			if (!iswithin(pbase[j], ranges[j].size, addr, size))
				continue;
			
			/* Switch the command to a kernel virtual address. */
			addr -= pbase[j];
			addr += ranges[j].base;
			
			cmds[i].addr = (void *) addr;
			break;
		}
		
		if (j == rangecount) {
			/*
			 * The address used in this command is outside of all
			 * defined ranges.
			 */
			ranges_unmap(ranges, rangecount);
			free(pbase);
			return EINVAL;
		}
	}
	
	free(pbase);
	return EOK;
}

/** Statically check the top-half pseudocode
 *
 * Check the top-half pseudocode for invalid or unsafe
 * constructs.
 *
 */
static int code_check(irq_cmd_t *cmds, size_t cmdcount)
{
	for (size_t i = 0; i < cmdcount; i++) {
		/*
		 * Check for accepted ranges.
		 */
		if (cmds[i].cmd >= CMD_LAST)
			return EINVAL;
		
		if (cmds[i].srcarg >= IPC_CALL_LEN)
			return EINVAL;
		
		if (cmds[i].dstarg >= IPC_CALL_LEN)
			return EINVAL;
		
		switch (cmds[i].cmd) {
		case CMD_PREDICATE:
			/*
			 * Check for control flow overflow.
			 * Note that jumping just beyond the last
			 * command is a correct behaviour.
			 */
			if (i + cmds[i].value > cmdcount)
				return EINVAL;
			
			break;
		default:
			break;
		}
	}
	
	return EOK;
}

/** Free the top-half pseudocode.
 *
 * @param code Pointer to the top-half pseudocode.
 *
 */
static void code_free(irq_code_t *code)
{
	if (code) {
		ranges_unmap(code->ranges, code->rangecount);
		free(code->ranges);
		free(code->cmds);
		free(code);
	}
}

/** Copy the top-half pseudocode from userspace into the kernel.
 *
 * @param ucode Userspace address of the top-half pseudocode.
 *
 * @return Kernel address of the copied pseudocode.
 *
 */
static irq_code_t *code_from_uspace(irq_code_t *ucode)
{
	irq_pio_range_t *ranges = NULL;
	irq_cmd_t *cmds = NULL;
	
	irq_code_t *code = malloc(sizeof(*code), 0);
	int rc = copy_from_uspace(code, ucode, sizeof(*code));
	if (rc != EOK)
		goto error;
	
	if ((code->rangecount > IRQ_MAX_RANGE_COUNT) ||
	    (code->cmdcount > IRQ_MAX_PROG_SIZE))
		goto error;
	
	ranges = malloc(sizeof(code->ranges[0]) * code->rangecount, 0);
	rc = copy_from_uspace(ranges, code->ranges,
	    sizeof(code->ranges[0]) * code->rangecount);
	if (rc != EOK)
		goto error;
	
	cmds = malloc(sizeof(code->cmds[0]) * code->cmdcount, 0);
	rc = copy_from_uspace(cmds, code->cmds,
	    sizeof(code->cmds[0]) * code->cmdcount);
	if (rc != EOK)
		goto error;
	
	rc = code_check(cmds, code->cmdcount);
	if (rc != EOK)
		goto error;
	
	rc = ranges_map_and_apply(ranges, code->rangecount, cmds,
	    code->cmdcount);
	if (rc != EOK)
		goto error;
	
	code->ranges = ranges;
	code->cmds = cmds;
	
	return code;
	
error:
	if (cmds)
		free(cmds);
	
	if (ranges)
		free(ranges);
	
	free(code);
	return NULL;
}

/** Register an answerbox as a receiving end for IRQ notifications.
 *
 * @param box     Receiving answerbox.
 * @param inr     IRQ number.
 * @param devno   Device number.
 * @param imethod Interface and method to be associated with the
 *                notification.
 * @param ucode   Uspace pointer to top-half pseudocode.
 *
 * @return EOK on success or a negative error code.
 *
 */
int ipc_irq_register(answerbox_t *box, inr_t inr, devno_t devno,
    sysarg_t imethod, irq_code_t *ucode)
{
	sysarg_t key[] = {
		(sysarg_t) inr,
		(sysarg_t) devno
	};
	
	if ((inr < 0) || (inr > last_inr))
		return ELIMIT;
	
	irq_code_t *code;
	if (ucode) {
		code = code_from_uspace(ucode);
		if (!code)
			return EBADMEM;
	} else
		code = NULL;
	
	/*
	 * Allocate and populate the IRQ structure.
	 */
	irq_t *irq = malloc(sizeof(irq_t), 0);
	
	irq_initialize(irq);
	irq->devno = devno;
	irq->inr = inr;
	irq->claim = ipc_irq_top_half_claim;
	irq->handler = ipc_irq_top_half_handler;
	irq->notif_cfg.notify = true;
	irq->notif_cfg.answerbox = box;
	irq->notif_cfg.imethod = imethod;
	irq->notif_cfg.code = code;
	irq->notif_cfg.counter = 0;
	
	/*
	 * Enlist the IRQ structure in the uspace IRQ hash table and the
	 * answerbox's list.
	 */
	irq_spinlock_lock(&irq_uspace_hash_table_lock, true);
	
	link_t *hlp = hash_table_find(&irq_uspace_hash_table, key);
	if (hlp) {
		irq_t *hirq = hash_table_get_instance(hlp, irq_t, link);
		
		/* hirq is locked */
		irq_spinlock_unlock(&hirq->lock, false);
		code_free(code);
		irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
		
		free(irq);
		return EEXISTS;
	}
	
	/* Locking is not really necessary, but paranoid */
	irq_spinlock_lock(&irq->lock, false);
	irq_spinlock_lock(&box->irq_lock, false);
	
	hash_table_insert(&irq_uspace_hash_table, key, &irq->link);
	list_append(&irq->notif_cfg.link, &box->irq_list);
	
	irq_spinlock_unlock(&box->irq_lock, false);
	irq_spinlock_unlock(&irq->lock, false);
	irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
	
	return EOK;
}

/** Unregister task from IRQ notification.
 *
 * @param box   Answerbox associated with the notification.
 * @param inr   IRQ number.
 * @param devno Device number.
 *
 * @return EOK on success or a negative error code.
 *
 */
int ipc_irq_unregister(answerbox_t *box, inr_t inr, devno_t devno)
{
	sysarg_t key[] = {
		(sysarg_t) inr,
		(sysarg_t) devno
	};
	
	if ((inr < 0) || (inr > last_inr))
		return ELIMIT;
	
	irq_spinlock_lock(&irq_uspace_hash_table_lock, true);
	link_t *lnk = hash_table_find(&irq_uspace_hash_table, key);
	if (!lnk) {
		irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
		return ENOENT;
	}
	
	irq_t *irq = hash_table_get_instance(lnk, irq_t, link);
	
	/* irq is locked */
	irq_spinlock_lock(&box->irq_lock, false);
	
	ASSERT(irq->notif_cfg.answerbox == box);
	
	/* Remove the IRQ from the answerbox's list. */
	list_remove(&irq->notif_cfg.link);
	
	/*
	 * We need to drop the IRQ lock now because hash_table_remove() will try
	 * to reacquire it. That basically violates the natural locking order,
	 * but a deadlock in hash_table_remove() is prevented by the fact that
	 * we already held the IRQ lock and didn't drop the hash table lock in
	 * the meantime.
	 */
	irq_spinlock_unlock(&irq->lock, false);
	
	/* Remove the IRQ from the uspace IRQ hash table. */
	hash_table_remove(&irq_uspace_hash_table, key, 2);
	
	irq_spinlock_unlock(&box->irq_lock, false);
	irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
	
	/* Free up the pseudo code and associated structures. */
	code_free(irq->notif_cfg.code);
	
	/* Free up the IRQ structure. */
	free(irq);
	
	return EOK;
}

/** Disconnect all IRQ notifications from an answerbox.
 *
 * This function is effective because the answerbox contains
 * list of all irq_t structures that are registered to
 * send notifications to it.
 *
 * @param box Answerbox for which we want to carry out the cleanup.
 *
 */
void ipc_irq_cleanup(answerbox_t *box)
{
loop:
	irq_spinlock_lock(&irq_uspace_hash_table_lock, true);
	irq_spinlock_lock(&box->irq_lock, false);
	
	while (!list_empty(&box->irq_list)) {
		DEADLOCK_PROBE_INIT(p_irqlock);
		
		irq_t *irq = list_get_instance(list_first(&box->irq_list), irq_t,
		    notif_cfg.link);
		
		if (!irq_spinlock_trylock(&irq->lock)) {
			/*
			 * Avoid deadlock by trying again.
			 */
			irq_spinlock_unlock(&box->irq_lock, false);
			irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
			DEADLOCK_PROBE(p_irqlock, DEADLOCK_THRESHOLD);
			goto loop;
		}
		
		sysarg_t key[2];
		key[0] = irq->inr;
		key[1] = irq->devno;
		
		ASSERT(irq->notif_cfg.answerbox == box);
		
		/* Unlist from the answerbox. */
		list_remove(&irq->notif_cfg.link);
		
		/*
		 * We need to drop the IRQ lock now because hash_table_remove()
		 * will try to reacquire it. That basically violates the natural
		 * locking order, but a deadlock in hash_table_remove() is
		 * prevented by the fact that we already held the IRQ lock and
		 * didn't drop the hash table lock in the meantime.
		 */
		irq_spinlock_unlock(&irq->lock, false);
		
		/* Remove from the hash table. */
		hash_table_remove(&irq_uspace_hash_table, key, 2);
		
		/*
		 * Release both locks so that we can free the pseudo code.
		 */
		irq_spinlock_unlock(&box->irq_lock, false);
		irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
		
		code_free(irq->notif_cfg.code);
		free(irq);
		
		/* Reacquire both locks before taking another round. */
		irq_spinlock_lock(&irq_uspace_hash_table_lock, true);
		irq_spinlock_lock(&box->irq_lock, false);
	}
	
	irq_spinlock_unlock(&box->irq_lock, false);
	irq_spinlock_unlock(&irq_uspace_hash_table_lock, true);
}

/** Add a call to the proper answerbox queue.
 *
 * Assume irq->lock is locked and interrupts disabled.
 *
 * @param irq  IRQ structure referencing the target answerbox.
 * @param call IRQ notification call.
 *
 */
static void send_call(irq_t *irq, call_t *call)
{
	irq_spinlock_lock(&irq->notif_cfg.answerbox->irq_lock, false);
	list_append(&call->ab_link, &irq->notif_cfg.answerbox->irq_notifs);
	irq_spinlock_unlock(&irq->notif_cfg.answerbox->irq_lock, false);
	
	waitq_wakeup(&irq->notif_cfg.answerbox->wq, WAKEUP_FIRST);
}

/** Apply the top-half pseudo code to find out whether to accept the IRQ or not.
 *
 * @param irq IRQ structure.
 *
 * @return IRQ_ACCEPT if the interrupt is accepted by the
 *         pseudocode, IRQ_DECLINE otherwise.
 *
 */
irq_ownership_t ipc_irq_top_half_claim(irq_t *irq)
{
	irq_code_t *code = irq->notif_cfg.code;
	uint32_t *scratch = irq->notif_cfg.scratch;
	
	if (!irq->notif_cfg.notify)
		return IRQ_DECLINE;
	
	if (!code)
		return IRQ_DECLINE;
	
	for (size_t i = 0; i < code->cmdcount; i++) {
		uintptr_t srcarg = code->cmds[i].srcarg;
		uintptr_t dstarg = code->cmds[i].dstarg;
		
		switch (code->cmds[i].cmd) {
		case CMD_PIO_READ_8:
			scratch[dstarg] =
			    pio_read_8((ioport8_t *) code->cmds[i].addr);
			break;
		case CMD_PIO_READ_16:
			scratch[dstarg] =
			    pio_read_16((ioport16_t *) code->cmds[i].addr);
			break;
		case CMD_PIO_READ_32:
			scratch[dstarg] =
			    pio_read_32((ioport32_t *) code->cmds[i].addr);
			break;
		case CMD_PIO_WRITE_8:
			pio_write_8((ioport8_t *) code->cmds[i].addr,
			    (uint8_t) code->cmds[i].value);
			break;
		case CMD_PIO_WRITE_16:
			pio_write_16((ioport16_t *) code->cmds[i].addr,
			    (uint16_t) code->cmds[i].value);
			break;
		case CMD_PIO_WRITE_32:
			pio_write_32((ioport32_t *) code->cmds[i].addr,
			    (uint32_t) code->cmds[i].value);
			break;
		case CMD_PIO_WRITE_A_8:
			pio_write_8((ioport8_t *) code->cmds[i].addr,
			    (uint8_t) scratch[srcarg]);
			break;
		case CMD_PIO_WRITE_A_16:
			pio_write_16((ioport16_t *) code->cmds[i].addr,
			    (uint16_t) scratch[srcarg]);
			break;
		case CMD_PIO_WRITE_A_32:
			pio_write_32((ioport32_t *) code->cmds[i].addr,
			    (uint32_t) scratch[srcarg]);
			break;
		case CMD_LOAD:
			scratch[dstarg] = code->cmds[i].value;
			break;
		case CMD_AND:
			scratch[dstarg] = scratch[srcarg] &
			    code->cmds[i].value;
			break;
		case CMD_PREDICATE:
			if (scratch[srcarg] == 0)
				i += code->cmds[i].value;
			
			break;
		case CMD_ACCEPT:
			return IRQ_ACCEPT;
		case CMD_DECLINE:
		default:
			return IRQ_DECLINE;
		}
	}
	
	return IRQ_DECLINE;
}

/* IRQ top-half handler.
 *
 * We expect interrupts to be disabled and the irq->lock already held.
 *
 * @param irq IRQ structure.
 *
 */
void ipc_irq_top_half_handler(irq_t *irq)
{
	ASSERT(irq);
	
	ASSERT(interrupts_disabled());
	ASSERT(irq_spinlock_locked(&irq->lock));
	
	if (irq->notif_cfg.answerbox) {
		call_t *call = ipc_call_alloc(FRAME_ATOMIC);
		if (!call)
			return;
		
		call->flags |= IPC_CALL_NOTIF;
		/* Put a counter to the message */
		call->priv = ++irq->notif_cfg.counter;
		
		/* Set up args */
		IPC_SET_IMETHOD(call->data, irq->notif_cfg.imethod);
		IPC_SET_ARG1(call->data, irq->notif_cfg.scratch[1]);
		IPC_SET_ARG2(call->data, irq->notif_cfg.scratch[2]);
		IPC_SET_ARG3(call->data, irq->notif_cfg.scratch[3]);
		IPC_SET_ARG4(call->data, irq->notif_cfg.scratch[4]);
		IPC_SET_ARG5(call->data, irq->notif_cfg.scratch[5]);
		
		send_call(irq, call);
	}
}

/** Send notification message.
 *
 * @param irq IRQ structure.
 * @param a1  Driver-specific payload argument.
 * @param a2  Driver-specific payload argument.
 * @param a3  Driver-specific payload argument.
 * @param a4  Driver-specific payload argument.
 * @param a5  Driver-specific payload argument.
 *
 */
void ipc_irq_send_msg(irq_t *irq, sysarg_t a1, sysarg_t a2, sysarg_t a3,
    sysarg_t a4, sysarg_t a5)
{
	irq_spinlock_lock(&irq->lock, true);
	
	if (irq->notif_cfg.answerbox) {
		call_t *call = ipc_call_alloc(FRAME_ATOMIC);
		if (!call) {
			irq_spinlock_unlock(&irq->lock, true);
			return;
		}
		
		call->flags |= IPC_CALL_NOTIF;
		/* Put a counter to the message */
		call->priv = ++irq->notif_cfg.counter;
		
		IPC_SET_IMETHOD(call->data, irq->notif_cfg.imethod);
		IPC_SET_ARG1(call->data, a1);
		IPC_SET_ARG2(call->data, a2);
		IPC_SET_ARG3(call->data, a3);
		IPC_SET_ARG4(call->data, a4);
		IPC_SET_ARG5(call->data, a5);
		
		send_call(irq, call);
	}
	
	irq_spinlock_unlock(&irq->lock, true);
}

/** @}
 */