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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.

 */

/** @addtogroup genericddi

 * @{

 */

/**

 * @file

 * @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 <adt/btree.h>

#include <arch.h>

#include <align.h>

#include <errno.h>

/** This lock protects the parea_btree. */

SPINLOCK_INITIALIZE(parea_lock);

/** B+tree with enabled physical memory areas. */

static btree_t parea_btree;

/** Initialize DDI. */

void ddi_init(void)

{

    btree_create(&parea_btree);

}

/** Enable piece of physical memory for mapping by physmem_map().

 *

 * @param parea Pointer to physical area structure.

 *

 * @todo This function doesn't check for overlaps. It depends on the kernel to

 * create disjunct physical memory areas.

 */

void ddi_parea_register(parea_t *parea)

{

    ipl_t ipl;

    ipl = interrupts_disable();

    spinlock_lock(&parea_lock);

    /*

     * TODO: we should really check for overlaps here.

     * However, we should be safe because the kernel is pretty sane and

     * memory of different devices doesn't overlap.

     */

    btree_insert(&parea_btree, (btree_key_t) parea->pbase, parea, NULL);

    spinlock_unlock(&parea_lock);

    interrupts_restore(ipl);   

}

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

 *

 * @param pf Physical address of the starting frame.

 * @param vp Virtual address of the starting page.

 * @param pages Number of pages to map.

 * @param flags Address space area flags for the mapping.

 *

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

 *  syscall, ENOENT if there is no task matching the specified ID or the

 *  physical address space is not enabled for mapping and ENOMEM if there

 *  was a problem in creating address space area. ENOTSUP is returned when

 *  an attempt to create an illegal address alias is detected.

 */

static int ddi_physmem_map(uintptr_t pf, uintptr_t vp, count_t pages, int flags)

{

    ipl_t ipl;

    cap_t caps;

    mem_backend_data_t backend_data;

    backend_data.base = pf;

    backend_data.frames = 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();

    /*

     * Check if the physical memory area is enabled for mapping.

     * If the architecture supports virtually indexed caches, intercept

     * attempts to create an illegal address alias.

     */

    spinlock_lock(&parea_lock);

    parea_t *parea;

    btree_node_t *nodep;

    parea = btree_search(&parea_btree, (btree_key_t) pf, &nodep);

    if (!parea || parea->frames < pages || ((flags & AS_AREA_CACHEABLE) &&

        !parea->cacheable) || (!(flags & AS_AREA_CACHEABLE) &&

        parea->cacheable)) {

        /*

         * This physical memory area cannot be mapped.

         */

        spinlock_unlock(&parea_lock);

        interrupts_restore(ipl);

        return ENOENT;

    }

#ifdef CONFIG_VIRT_IDX_DCACHE

    if (PAGE_COLOR(parea->vbase) != PAGE_COLOR(vp)) {

        /*

         * Refuse to create an illegal address alias.

         */

        spinlock_unlock(&parea_lock);

        interrupts_restore(ipl);

        return ENOTSUP;

    }

#endif /* CONFIG_VIRT_IDX_DCACHE */

    spinlock_unlock(&parea_lock);

    spinlock_lock(&TASK->lock);

    if (!as_area_create(TASK->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(&TASK->lock);

        interrupts_restore(ipl);

        return ENOMEM;

    }

    /*

     * Mapping is created on-demand during page fault.

     */

    spinlock_unlock(&TASK->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, uintptr_t 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) || (!context_check(CONTEXT, t->context))) {

        /*

         * There is no task with the specified ID

         * or the task belongs to a different security

         * context.

         */

        spinlock_unlock(&tasks_lock);

        interrupts_restore(ipl);

        return ENOENT;

    }

    /* 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_PHYSMEM_MAP syscall.

 *

 * @param phys_base Physical base address to map

 * @param virt_base Destination virtual address

 * @param pages Number of pages

 * @param flags Flags of newly mapped pages

 *

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

 */

unative_t sys_physmem_map(unative_t phys_base, unative_t virt_base, unative_t

    pages, unative_t flags)

{

    return (unative_t) ddi_physmem_map(ALIGN_DOWN((uintptr_t) phys_base,

        FRAME_SIZE), ALIGN_DOWN((uintptr_t) virt_base, PAGE_SIZE),

        (count_t) pages, (int) flags);

}

/** Wrapper for SYS_ENABLE_IOSPACE syscall.

 *

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

 *

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

 */

unative_t 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 (unative_t) rc;

    return (unative_t) ddi_iospace_enable((task_id_t) arg.task_id,

        (uintptr_t) 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.

 */

unative_t sys_preempt_control(int enable)

{

        if (! cap_get(TASK) & CAP_PREEMPT_CONTROL)

                return EPERM;

        if (enable)

                preemption_enable();

        else

                preemption_disable();

        return 0;

}

/** @}

 */