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/*

 * 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.

 */

/**

 * @file	ddi.c

 * @brief	Device Driver Interface functions.

 *

 * This file contains functions that comprise the Device Driver Interface.

 * These are the functions for mapping physical memory and enabling I/O

 * space to tasks.

 */

#include <ddi/ddi.h>

#include <ddi/ddi_arg.h>

#include <proc/task.h>

#include <security/cap.h>

#include <mm/frame.h>

#include <mm/as.h>

#include <synch/spinlock.h>

#include <syscall/copy.h>

#include <arch.h>

#include <align.h>

#include <errno.h>

/** Map piece of physical memory into virtual address space of specified task.

 *

 * @param id Task ID of the destination task.

 * @param pf Physical frame address of the starting frame.

 * @param vp Virtual page address of the starting page.

 * @param pages Number of pages to map.

 * @param writable If true, the mapping will be created writable.

 *

 * @return 0 on success, EPERM if the caller lacks capabilities to use this syscall,

 *	   ENOENT if there is no task matching the specified ID and ENOMEM if

 *	   there was a problem in creating address space area.

 */

static int ddi_physmem_map(task_id_t id, __address pf, __address vp, count_t pages, bool writable)

{

	ipl_t ipl;

	cap_t caps;

	task_t *t;

	int flags;

	mem_backend_data_t backend_data = { .d1 = (__native) pf, .d2 = (__native) pages };

	/*

	 * Make sure the caller is authorised to make this syscall.

	 */

	caps = cap_get(TASK);

	if (!(caps & CAP_MEM_MANAGER))

		return EPERM;

	ipl = interrupts_disable();

	spinlock_lock(&tasks_lock);

	t = task_find_by_id(id);

	if (!t) {

		/*

		 * There is no task with the specified ID.

		 */

		spinlock_unlock(&tasks_lock);

		interrupts_restore(ipl);

		return ENOENT;

	}

	/*

	 * TODO: We are currently lacking support for task destroying.

	 * Once it is added to the kernel, we must take care to

	 * synchronize in a way that prevents race conditions here.

	 */

	/* Lock the task and release the lock protecting tasks_btree. */

	spinlock_lock(&t->lock);

	spinlock_unlock(&tasks_lock);

	flags = AS_AREA_READ;

	if (writable)

		flags |= AS_AREA_WRITE;

	if (!as_area_create(t->as, flags, pages * PAGE_SIZE, vp, AS_AREA_ATTR_NONE,

		&phys_backend, &backend_data)) {

		/*

		 * The address space area could not have been created.

		 * We report it using ENOMEM.

		 */

		spinlock_unlock(&t->lock);

		interrupts_restore(ipl);

		return ENOMEM;

	}

	/*

	 * Mapping is created on-demand during page fault.

	 */

	spinlock_unlock(&t->lock);

	interrupts_restore(ipl);

	return 0;

}

/** Enable range of I/O space for task.

 *

 * @param id Task ID of the destination task.

 * @param ioaddr Starting I/O address.

 * @param size Size of the enabled I/O space..

 *

 * @return 0 on success, EPERM if the caller lacks capabilities to use this syscall,

 *	   ENOENT if there is no task matching the specified ID.

 */

static int ddi_iospace_enable(task_id_t id, __address ioaddr, size_t size)

{

	ipl_t ipl;

	cap_t caps;

	task_t *t;

	int rc;

	/*

	 * Make sure the caller is authorised to make this syscall.

	 */

	caps = cap_get(TASK);

	if (!(caps & CAP_IO_MANAGER))

		return EPERM;

	ipl = interrupts_disable();

	spinlock_lock(&tasks_lock);

	t = task_find_by_id(id);

	if (!t) {

		/*

		 * There is no task with the specified ID.

		 */

		spinlock_unlock(&tasks_lock);

		interrupts_restore(ipl);

		return ENOENT;

	}

	/*

	 * TODO: We are currently lacking support for task destroying.

	 * Once it is added to the kernel, we must take care to

	 * synchronize in a way that prevents race conditions here.

	 */

	/* Lock the task and release the lock protecting tasks_btree. */

	spinlock_lock(&t->lock);

	spinlock_unlock(&tasks_lock);

	rc = ddi_iospace_enable_arch(t, ioaddr, size);

	spinlock_unlock(&t->lock);

	interrupts_restore(ipl);

	return rc;

}

/** Wrapper for SYS_MAP_PHYSMEM syscall.

 *

 * @param User space address of memory DDI argument structure.

 *

 * @return 0 on success, otherwise it returns error code found in errno.h

 */ 

__native sys_physmem_map(ddi_memarg_t *uspace_mem_arg)

{

	ddi_memarg_t arg;

	int rc;

	rc = copy_from_uspace(&arg, uspace_mem_arg, sizeof(ddi_memarg_t));

	if (rc != 0)

		return (__native) rc;

	return (__native) ddi_physmem_map((task_id_t) arg.task_id, ALIGN_DOWN((__address) arg.phys_base, FRAME_SIZE),

					  ALIGN_DOWN((__address) arg.virt_base, PAGE_SIZE), (count_t) arg.pages,

					  (bool) arg.writable);

}

/** Wrapper for SYS_ENABLE_IOSPACE syscall.

 *

 * @param User space address of DDI argument structure.

 *

 * @return 0 on success, otherwise it returns error code found in errno.h

 */ 

__native sys_iospace_enable(ddi_ioarg_t *uspace_io_arg)

{

	ddi_ioarg_t arg;

	int rc;

	rc = copy_from_uspace(&arg, uspace_io_arg, sizeof(ddi_ioarg_t));

	if (rc != 0)

		return (__native) rc;

	return (__native) ddi_iospace_enable((task_id_t) arg.task_id, (__address) arg.ioaddr, (size_t) arg.size);

}

/** Disable or enable preemption.

 *

 * @param enable If non-zero, the preemption counter will be decremented, leading to potential

 * 		 enabling of preemption. Otherwise the preemption counter will be incremented,

 *		 preventing preemption from occurring.

 *

 * @return Zero on success or EPERM if callers capabilities are not sufficient.

 */ 

__native sys_preempt_control(int enable)

{

        if (! cap_get(TASK) & CAP_PREEMPT_CONTROL)

                return EPERM;

        if (enable)

                preemption_enable();

        else

                preemption_disable();

        return 0;

}