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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;

}