source: mainline/uspace/srv/devman/fun.c@ ca48672

/*
 * Copyright (c) 2025 Jiri Svoboda
 * Copyright (c) 2010 Lenka Trochtova
 * 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 devman
 * @{
 */

#include <errno.h>
#include <io/log.h>
#include <loc.h>

#include "dev.h"
#include "devman.h"
#include "devtree.h"
#include "driver.h"
#include "fun.h"
#include "main.h"
#include "loc.h"

static fun_node_t *find_node_child(dev_tree_t *, fun_node_t *, const char *);

/* Function nodes */

/** Create a new function node.
 *
 * @return              A function node structure.
 */
fun_node_t *create_fun_node(void)
{
        fun_node_t *fun;

        fun = calloc(1, sizeof(fun_node_t));
        if (fun == NULL)
                return NULL;

        fun->state = FUN_INIT;
        refcount_init(&fun->refcnt);
        fibril_mutex_initialize(&fun->busy_lock);
        link_initialize(&fun->dev_functions);
        list_initialize(&fun->match_ids.ids);

        return fun;
}

/** Delete a function node.
 *
 * @param fun           The device node structure.
 */
void delete_fun_node(fun_node_t *fun)
{
        assert(fun->dev == NULL);
        assert(fun->child == NULL);

        clean_match_ids(&fun->match_ids);
        free(fun->name);
        free(fun->pathname);
        free(fun);
}

/** Increase function node reference count.
 *
 * @param fun   Function node
 */
void fun_add_ref(fun_node_t *fun)
{
        refcount_up(&fun->refcnt);
}

/** Decrease function node reference count.
 *
 * When the count drops to zero the function node is freed.
 *
 * @param fun   Function node
 */
void fun_del_ref(fun_node_t *fun)
{
        if (refcount_down(&fun->refcnt))
                delete_fun_node(fun);
}

/** Make function busy for reconfiguration operations. */
void fun_busy_lock(fun_node_t *fun)
{
        fibril_mutex_lock(&fun->busy_lock);
}

/** Mark end of reconfiguration operation. */
void fun_busy_unlock(fun_node_t *fun)
{
        fibril_mutex_unlock(&fun->busy_lock);
}

/** Find the function node with the specified handle.
 *
 * @param tree          The device tree where we look for the device node.
 * @param handle        The handle of the function.
 * @return              The function node.
 */
fun_node_t *find_fun_node_no_lock(dev_tree_t *tree, devman_handle_t handle)
{
        fun_node_t *fun;

        assert(fibril_rwlock_is_locked(&tree->rwlock));

        ht_link_t *link = hash_table_find(&tree->devman_functions, &handle);
        if (link == NULL)
                return NULL;

        fun = hash_table_get_inst(link, fun_node_t, devman_fun);

        return fun;
}

/** Find the function node with the specified handle.
 *
 * @param tree          The device tree where we look for the device node.
 * @param handle        The handle of the function.
 * @return              The function node.
 */
fun_node_t *find_fun_node(dev_tree_t *tree, devman_handle_t handle)
{
        fun_node_t *fun = NULL;

        fibril_rwlock_read_lock(&tree->rwlock);

        fun = find_fun_node_no_lock(tree, handle);
        if (fun != NULL)
                fun_add_ref(fun);

        fibril_rwlock_read_unlock(&tree->rwlock);

        return fun;
}

/** Create and set device's full path in device tree.
 *
 * @param tree          Device tree
 * @param node          The device's device node.
 * @param parent        The parent device node.
 * @return              True on success, false otherwise (insufficient
 *                      resources etc.).
 */
bool set_fun_path(dev_tree_t *tree, fun_node_t *fun, fun_node_t *parent)
{
        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
        assert(fun->name != NULL);

        size_t pathsize = (str_size(fun->name) + 1);
        if (parent != NULL)
                pathsize += str_size(parent->pathname) + 1;

        fun->pathname = (char *) malloc(pathsize);
        if (fun->pathname == NULL) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Failed to allocate device path.");
                return false;
        }

        if (parent != NULL) {
                str_cpy(fun->pathname, pathsize, parent->pathname);
                str_append(fun->pathname, pathsize, "/");
                str_append(fun->pathname, pathsize, fun->name);
        } else {
                str_cpy(fun->pathname, pathsize, fun->name);
        }

        return true;
}

/** Find function node with a specified path in the device tree.
 *
 * @param path          The path of the function node in the device tree.
 * @param tree          The device tree.
 * @return              The function node if it is present in the tree, NULL
 *                      otherwise.
 */
fun_node_t *find_fun_node_by_path(dev_tree_t *tree, char *path)
{
        assert(path != NULL);

        bool is_absolute = path[0] == '/';
        if (!is_absolute) {
                return NULL;
        }

        fibril_rwlock_read_lock(&tree->rwlock);

        fun_node_t *fun = tree->root_node;
        fun_add_ref(fun);
        /*
         * Relative path to the function from its parent (but with '/' at the
         * beginning)
         */
        char *rel_path = path;
        char *next_path_elem = NULL;
        bool cont = (rel_path[1] != '\0');

        while (cont && fun != NULL) {
                next_path_elem  = get_path_elem_end(rel_path + 1);
                if (next_path_elem[0] == '/') {
                        cont = true;
                        next_path_elem[0] = 0;
                } else {
                        cont = false;
                }

                fun_node_t *cfun = find_node_child(tree, fun, rel_path + 1);
                fun_del_ref(fun);
                fun = cfun;

                if (cont) {
                        /* Restore the original path. */
                        next_path_elem[0] = '/';
                }
                rel_path = next_path_elem;
        }

        fibril_rwlock_read_unlock(&tree->rwlock);

        return fun;
}

/** Find function with a specified name belonging to given device.
 *
 * Device tree rwlock should be held at least for reading.
 *
 * @param tree Device tree
 * @param dev Device the function belongs to.
 * @param name Function name (not path).
 * @return Function node.
 * @retval NULL No function with given name.
 */
fun_node_t *find_fun_node_in_device(dev_tree_t *tree, dev_node_t *dev,
    const char *name)
{
        assert(name != NULL);
        assert(fibril_rwlock_is_locked(&tree->rwlock));

        list_foreach(dev->functions, dev_functions, fun_node_t, fun) {
                if (str_cmp(name, fun->name) == 0) {
                        fun_add_ref(fun);
                        return fun;
                }
        }

        return NULL;
}

/** Find child function node with a specified name.
 *
 * Device tree rwlock should be held at least for reading.
 *
 * @param tree          Device tree
 * @param parent        The parent function node.
 * @param name          The name of the child function.
 * @return              The child function node.
 */
static fun_node_t *find_node_child(dev_tree_t *tree, fun_node_t *pfun,
    const char *name)
{
        return find_fun_node_in_device(tree, pfun->child, name);
}

static errno_t assign_driver_fibril(void *arg)
{
        dev_node_t *dev_node = (dev_node_t *) arg;
        assign_driver(dev_node, &drivers_list, &device_tree);

        /* Delete one reference we got from the caller. */
        dev_del_ref(dev_node);
        return EOK;
}

errno_t fun_online(fun_node_t *fun)
{
        dev_node_t *dev;

        fibril_rwlock_write_lock(&device_tree.rwlock);

        if (fun->state == FUN_ON_LINE) {
                fibril_rwlock_write_unlock(&device_tree.rwlock);
                log_msg(LOG_DEFAULT, LVL_WARN, "Function %s is already on line.",
                    fun->pathname);
                return EOK;
        }

        if (fun->ftype == fun_inner) {
                dev = create_dev_node();
                if (dev == NULL) {
                        fibril_rwlock_write_unlock(&device_tree.rwlock);
                        return ENOMEM;
                }

                insert_dev_node(&device_tree, dev, fun);
        }

        log_msg(LOG_DEFAULT, LVL_DEBUG, "devman_add_function(fun=\"%s\")", fun->pathname);

        if (fun->ftype == fun_inner) {
                dev = fun->child;
                assert(dev != NULL);

                /* Give one reference over to assign_driver_fibril(). */
                dev_add_ref(dev);

                /*
                 * Try to find a suitable driver and assign it to the device.  We do
                 * not want to block the current fibril that is used for processing
                 * incoming calls: we will launch a separate fibril to handle the
                 * driver assigning. That is because assign_driver can actually include
                 * task spawning which could take some time.
                 */
                fid_t assign_fibril = fibril_create(assign_driver_fibril, dev);
                if (assign_fibril == 0) {
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Failed to create fibril for "
                            "assigning driver.");
                        /* XXX Cleanup */
                        fibril_rwlock_write_unlock(&device_tree.rwlock);
                        return ENOMEM;
                }
                fibril_add_ready(assign_fibril);
        } else
                loc_register_tree_function(fun, &device_tree);

        fun->state = FUN_ON_LINE;
        fibril_rwlock_write_unlock(&device_tree.rwlock);

        return EOK;
}

errno_t fun_offline(fun_node_t *fun)
{
        errno_t rc;

        fibril_rwlock_write_lock(&device_tree.rwlock);

        if (fun->state == FUN_OFF_LINE) {
                fibril_rwlock_write_unlock(&device_tree.rwlock);
                log_msg(LOG_DEFAULT, LVL_WARN, "Function %s is already off line.",
                    fun->pathname);
                return EOK;
        }

        if (fun->ftype == fun_inner) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Offlining inner function %s.",
                    fun->pathname);

                if (fun->child != NULL) {
                        dev_node_t *dev = fun->child;
                        device_state_t dev_state;

                        dev_add_ref(dev);
                        dev_state = dev->state;

                        fibril_rwlock_write_unlock(&device_tree.rwlock);

                        /* If device is owned by driver, ask driver to give it up. */
                        if (dev_state == DEVICE_USABLE) {
                                rc = driver_dev_remove(&device_tree, dev);
                                if (rc != EOK) {
                                        dev_del_ref(dev);
                                        return ENOTSUP;
                                }
                        }

                        /* Verify that driver removed all functions */
                        fibril_rwlock_read_lock(&device_tree.rwlock);
                        if (!list_empty(&dev->functions)) {
                                fibril_rwlock_read_unlock(&device_tree.rwlock);
                                dev_del_ref(dev);
                                return EIO;
                        }

                        driver_t *driver = dev->drv;
                        fibril_rwlock_read_unlock(&device_tree.rwlock);

                        if (driver)
                                detach_driver(&device_tree, dev);

                        fibril_rwlock_write_lock(&device_tree.rwlock);
                        remove_dev_node(&device_tree, dev);

                        /* Delete ref created when node was inserted */
                        dev_del_ref(dev);
                        /* Delete ref created by dev_add_ref(dev) above */
                        dev_del_ref(dev);
                }
        } else {
                /* Unregister from location service */
                rc = loc_unregister_tree_function(fun, &device_tree);
                if (rc != EOK) {
                        fibril_rwlock_write_unlock(&device_tree.rwlock);
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Failed unregistering tree service.");
                        return EIO;
                }

                fun->service_id = 0;
        }

        fun->state = FUN_OFF_LINE;
        fibril_rwlock_write_unlock(&device_tree.rwlock);

        return EOK;
}

errno_t fun_quiesce(fun_node_t *fun)
{
        errno_t rc;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "fun_quiesce(%s)", fun->pathname);
        fibril_rwlock_read_lock(&device_tree.rwlock);

        if (fun->state == FUN_OFF_LINE) {
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Function %s is off line.",
                    fun->pathname);
                return EOK;
        }

        if (fun->ftype != fun_inner) {
                /* Nothing to do */
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Nothing to do for external "
                    "function %s\n", fun->pathname);
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                return EOK;
        }

        log_msg(LOG_DEFAULT, LVL_DEBUG, "Quiescing inner function %s.",
            fun->pathname);

        if (fun->child == NULL) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Function %s child is NULL.",
                    fun->pathname);
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                return EOK;
        }

        dev_node_t *dev = fun->child;
        device_state_t dev_state;

        dev_add_ref(dev);
        dev_state = dev->state;

        fibril_rwlock_read_unlock(&device_tree.rwlock);

        /* If device is owned by driver, ask driver to quiesce it. */
        if (dev_state == DEVICE_USABLE) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Call driver_dev_quiesce() "
                    "for %s.", fun->pathname);
                rc = driver_dev_quiesce(&device_tree, dev);
                if (rc != EOK) {
                        log_msg(LOG_DEFAULT, LVL_ERROR,
                            "driver_dev_quiesce() -> %d", (int)rc);
                        dev_del_ref(dev);
                        return ENOTSUP;
                }
        }

        dev_del_ref(dev);
        return EOK;
}

/** @}
 */