source: mainline/uspace/srv/devman/devman.c@ feeac0d

/*
 * 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
 * @{
 */
/** @file Device Manager
 *
 * Locking order:
 *   (1) driver_t.driver_mutex
 *   (2) dev_tree_t.rwlock
 *
 * Synchronization:
 *    - device_tree.rwlock protects:
 *        - tree root, complete tree topology
 *        - complete contents of device and function nodes
 *    - dev_node_t.refcnt, fun_node_t.refcnt prevent nodes from
 *      being deallocated
 *    - find_xxx() functions increase reference count of returned object
 *    - find_xxx_no_lock() do not increase reference count
 *
 * TODO
 *    - Track all steady and transient device/function states
 *    - Check states, wait for steady state on certain operations
 */

#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <io/log.h>
#include <ipc/driver.h>
#include <ipc/devman.h>
#include <loc.h>
#include <str_error.h>
#include <stdio.h>

#include "devman.h"

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

/* hash table operations */

static inline size_t handle_key_hash(void *key)
{
        devman_handle_t handle = *(devman_handle_t*)key;
        return handle;
}

static size_t devman_devices_hash(const ht_link_t *item)
{
        dev_node_t *dev = hash_table_get_inst(item, dev_node_t, devman_dev);
        return handle_key_hash(&dev->handle);
}

static size_t devman_functions_hash(const ht_link_t *item)
{
        fun_node_t *fun = hash_table_get_inst(item, fun_node_t, devman_fun);
        return handle_key_hash(&fun->handle);
}

static bool devman_devices_key_equal(void *key, const ht_link_t *item)
{
        devman_handle_t handle = *(devman_handle_t*)key;
        dev_node_t *dev = hash_table_get_inst(item, dev_node_t, devman_dev);
        return dev->handle == handle;
}

static bool devman_functions_key_equal(void *key, const ht_link_t *item)
{
        devman_handle_t handle = *(devman_handle_t*)key;
        fun_node_t *fun = hash_table_get_inst(item, fun_node_t, devman_fun);
        return fun->handle == handle;
}

static inline size_t service_id_key_hash(void *key)
{
        service_id_t service_id = *(service_id_t*)key;
        return service_id;
}

static size_t loc_functions_hash(const ht_link_t *item)
{
        fun_node_t *fun = hash_table_get_inst(item, fun_node_t, loc_fun);
        return service_id_key_hash(&fun->service_id);
}

static bool loc_functions_key_equal(void *key, const ht_link_t *item)
{
        service_id_t service_id = *(service_id_t*)key;
        fun_node_t *fun = hash_table_get_inst(item, fun_node_t, loc_fun);
        return fun->service_id == service_id;
}


static hash_table_ops_t devman_devices_ops = {
        .hash = devman_devices_hash,
        .key_hash = handle_key_hash,
        .key_equal = devman_devices_key_equal,
        .equal = NULL,
        .remove_callback = NULL
};

static hash_table_ops_t devman_functions_ops = {
        .hash = devman_functions_hash,
        .key_hash = handle_key_hash,
        .key_equal = devman_functions_key_equal,
        .equal = NULL,
        .remove_callback = NULL
};

static hash_table_ops_t loc_devices_ops = {
        .hash = loc_functions_hash,
        .key_hash = service_id_key_hash,
        .key_equal = loc_functions_key_equal,
        .equal = NULL,
        .remove_callback = NULL
};

/**
 * Initialize the list of device driver's.
 *
 * @param drv_list the list of device driver's.
 *
 */
void init_driver_list(driver_list_t *drv_list)
{
        assert(drv_list != NULL);
        
        list_initialize(&drv_list->drivers);
        fibril_mutex_initialize(&drv_list->drivers_mutex);
}

/** Allocate and initialize a new driver structure.
 *
 * @return      Driver structure.
 */
driver_t *create_driver(void)
{
        driver_t *res = malloc(sizeof(driver_t));
        if (res != NULL)
                init_driver(res);
        return res;
}

/** Add a driver to the list of drivers.
 *
 * @param drivers_list  List of drivers.
 * @param drv           Driver structure.
 */
void add_driver(driver_list_t *drivers_list, driver_t *drv)
{
        fibril_mutex_lock(&drivers_list->drivers_mutex);
        list_prepend(&drv->drivers, &drivers_list->drivers);
        fibril_mutex_unlock(&drivers_list->drivers_mutex);

        log_msg(LOG_DEFAULT, LVL_NOTE, "Driver `%s' was added to the list of available "
            "drivers.", drv->name);
}

/** Read match id at the specified position of a string and set the position in
 * the string to the first character following the id.
 *
 * @param buf           The position in the input string.
 * @return              The match id.
 */
char *read_match_id(char **buf)
{
        char *res = NULL;
        size_t len = get_nonspace_len(*buf);
        
        if (len > 0) {
                res = malloc(len + 1);
                if (res != NULL) {
                        str_ncpy(res, len + 1, *buf, len);
                        *buf += len;
                }
        }
        
        return res;
}

/**
 * Read match ids and associated match scores from a string.
 *
 * Each match score in the string is followed by its match id.
 * The match ids and match scores are separated by whitespaces.
 * Neither match ids nor match scores can contain whitespaces.
 *
 * @param buf           The string from which the match ids are read.
 * @param ids           The list of match ids into which the match ids and
 *                      scores are added.
 * @return              True if at least one match id and associated match score
 *                      was successfully read, false otherwise.
 */
bool parse_match_ids(char *buf, match_id_list_t *ids)
{
        int score = 0;
        char *id = NULL;
        int ids_read = 0;
        
        while (true) {
                /* skip spaces */
                if (!skip_spaces(&buf))
                        break;
                
                /* read score */
                score = strtoul(buf, &buf, 10);
                
                /* skip spaces */
                if (!skip_spaces(&buf))
                        break;
                
                /* read id */
                id = read_match_id(&buf);
                if (NULL == id)
                        break;
                
                /* create new match_id structure */
                match_id_t *mid = create_match_id();
                mid->id = id;
                mid->score = score;
                
                /* add it to the list */
                add_match_id(ids, mid);
                
                ids_read++;
        }
        
        return ids_read > 0;
}

/**
 * Read match ids and associated match scores from a file.
 *
 * Each match score in the file is followed by its match id.
 * The match ids and match scores are separated by whitespaces.
 * Neither match ids nor match scores can contain whitespaces.
 *
 * @param buf           The path to the file from which the match ids are read.
 * @param ids           The list of match ids into which the match ids and
 *                      scores are added.
 * @return              True if at least one match id and associated match score
 *                      was successfully read, false otherwise.
 */
bool read_match_ids(const char *conf_path, match_id_list_t *ids)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "read_match_ids(conf_path=\"%s\")", conf_path);
        
        bool suc = false;
        char *buf = NULL;
        bool opened = false;
        int fd;
        size_t len = 0;
        
        fd = open(conf_path, O_RDONLY);
        if (fd < 0) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Unable to open `%s' for reading: %s.",
                    conf_path, str_error(fd));
                goto cleanup;
        }
        opened = true;
        
        len = lseek(fd, 0, SEEK_END);
        lseek(fd, 0, SEEK_SET);
        if (len == 0) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Configuration file '%s' is empty.",
                    conf_path);
                goto cleanup;
        }
        
        buf = malloc(len + 1);
        if (buf == NULL) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Memory allocation failed when parsing file "
                    "'%s'.", conf_path);
                goto cleanup;
        }
        
        ssize_t read_bytes = read_all(fd, buf, len);
        if (read_bytes <= 0) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Unable to read file '%s' (%zd).", conf_path,
                    read_bytes);
                goto cleanup;
        }
        buf[read_bytes] = 0;
        
        suc = parse_match_ids(buf, ids);
        
cleanup:
        free(buf);
        
        if (opened)
                close(fd);
        
        return suc;
}

/**
 * Get information about a driver.
 *
 * Each driver has its own directory in the base directory.
 * The name of the driver's directory is the same as the name of the driver.
 * The driver's directory contains driver's binary (named as the driver without
 * extension) and the configuration file with match ids for device-to-driver
 *  matching (named as the driver with a special extension).
 *
 * This function searches for the driver's directory and containing
 * configuration files. If all the files needed are found, they are parsed and
 * the information about the driver is stored in the driver's structure.
 *
 * @param base_path     The base directory, in which we look for driver's
 *                      subdirectory.
 * @param name          The name of the driver.
 * @param drv           The driver structure to fill information in.
 *
 * @return              True on success, false otherwise.
 */
bool get_driver_info(const char *base_path, const char *name, driver_t *drv)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "get_driver_info(base_path=\"%s\", name=\"%s\")",
            base_path, name);
        
        assert(base_path != NULL && name != NULL && drv != NULL);
        
        bool suc = false;
        char *match_path = NULL;
        size_t name_size = 0;
        
        /* Read the list of match ids from the driver's configuration file. */
        match_path = get_abs_path(base_path, name, MATCH_EXT);
        if (match_path == NULL)
                goto cleanup;
        
        if (!read_match_ids(match_path, &drv->match_ids))
                goto cleanup;
        
        /* Allocate and fill driver's name. */
        name_size = str_size(name) + 1;
        drv->name = malloc(name_size);
        if (drv->name == NULL)
                goto cleanup;
        str_cpy(drv->name, name_size, name);
        
        /* Initialize path with driver's binary. */
        drv->binary_path = get_abs_path(base_path, name, "");
        if (drv->binary_path == NULL)
                goto cleanup;
        
        /* Check whether the driver's binary exists. */
        struct stat s;
        if (stat(drv->binary_path, &s) == ENOENT) { /* FIXME!! */
                log_msg(LOG_DEFAULT, LVL_ERROR, "Driver not found at path `%s'.",
                    drv->binary_path);
                goto cleanup;
        }
        
        suc = true;
        
cleanup:
        if (!suc) {
                free(drv->binary_path);
                free(drv->name);
                /* Set the driver structure to the default state. */
                init_driver(drv);
        }
        
        free(match_path);
        
        return suc;
}

/** Lookup drivers in the directory.
 *
 * @param drivers_list  The list of available drivers.
 * @param dir_path      The path to the directory where we search for drivers.
 * @return              Number of drivers which were found.
 */
int lookup_available_drivers(driver_list_t *drivers_list, const char *dir_path)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "lookup_available_drivers(dir=\"%s\")", dir_path);
        
        int drv_cnt = 0;
        DIR *dir = NULL;
        struct dirent *diren;

        dir = opendir(dir_path);
        
        if (dir != NULL) {
                driver_t *drv = create_driver();
                while ((diren = readdir(dir))) {
                        if (get_driver_info(dir_path, diren->d_name, drv)) {
                                add_driver(drivers_list, drv);
                                drv_cnt++;
                                drv = create_driver();
                        }
                }
                delete_driver(drv);
                closedir(dir);
        }
        
        return drv_cnt;
}

/** Create root device and function node in the device tree.
 *
 * @param tree  The device tree.
 * @return      True on success, false otherwise.
 */
bool create_root_nodes(dev_tree_t *tree)
{
        fun_node_t *fun;
        dev_node_t *dev;
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "create_root_nodes()");
        
        fibril_rwlock_write_lock(&tree->rwlock);
        
        /*
         * Create root function. This is a pseudo function to which
         * the root device node is attached. It allows us to match
         * the root device driver in a standard manner, i.e. against
         * the parent function.
         */
        
        fun = create_fun_node();
        if (fun == NULL) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                return false;
        }
        
        fun_add_ref(fun);
        insert_fun_node(tree, fun, str_dup(""), NULL);
        
        match_id_t *id = create_match_id();
        id->id = str_dup("root");
        id->score = 100;
        add_match_id(&fun->match_ids, id);
        tree->root_node = fun;
        
        /*
         * Create root device node.
         */
        dev = create_dev_node();
        if (dev == NULL) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                return false;
        }
        
        dev_add_ref(dev);
        insert_dev_node(tree, dev, fun);
        
        fibril_rwlock_write_unlock(&tree->rwlock);
        
        return dev != NULL;
}

/** Lookup the best matching driver for the specified device in the list of
 * drivers.
 *
 * A match between a device and a driver is found if one of the driver's match
 * ids match one of the device's match ids. The score of the match is the
 * product of the driver's and device's score associated with the matching id.
 * The best matching driver for a device is the driver with the highest score
 * of the match between the device and the driver.
 *
 * @param drivers_list  The list of drivers, where we look for the driver
 *                      suitable for handling the device.
 * @param node          The device node structure of the device.
 * @return              The best matching driver or NULL if no matching driver
 *                      is found.
 */
driver_t *find_best_match_driver(driver_list_t *drivers_list, dev_node_t *node)
{
        driver_t *best_drv = NULL;
        int best_score = 0, score = 0;
        
        fibril_mutex_lock(&drivers_list->drivers_mutex);
        
        list_foreach(drivers_list->drivers, drivers, driver_t, drv) {
                score = get_match_score(drv, node);
                if (score > best_score) {
                        best_score = score;
                        best_drv = drv;
                }
        }
        
        fibril_mutex_unlock(&drivers_list->drivers_mutex);
        
        return best_drv;
}

/** Assign a driver to a device.
 *
 * @param tree          Device tree
 * @param node          The device's node in the device tree.
 * @param drv           The driver.
 */
void attach_driver(dev_tree_t *tree, dev_node_t *dev, driver_t *drv)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "attach_driver(dev=\"%s\",drv=\"%s\")",
            dev->pfun->pathname, drv->name);
        
        fibril_mutex_lock(&drv->driver_mutex);
        fibril_rwlock_write_lock(&tree->rwlock);
        
        dev->drv = drv;
        list_append(&dev->driver_devices, &drv->devices);
        
        fibril_rwlock_write_unlock(&tree->rwlock);
        fibril_mutex_unlock(&drv->driver_mutex);
}

/** Detach driver from device.
 *
 * @param tree          Device tree
 * @param node          The device's node in the device tree.
 * @param drv           The driver.
 */
void detach_driver(dev_tree_t *tree, dev_node_t *dev)
{
        driver_t *drv = dev->drv;
        
        assert(drv != NULL);
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "detach_driver(dev=\"%s\",drv=\"%s\")",
            dev->pfun->pathname, drv->name);
        
        fibril_mutex_lock(&drv->driver_mutex);
        fibril_rwlock_write_lock(&tree->rwlock);
        
        dev->drv = NULL;
        list_remove(&dev->driver_devices);
        
        fibril_rwlock_write_unlock(&tree->rwlock);
        fibril_mutex_unlock(&drv->driver_mutex);
}

/** Start a driver
 *
 * @param drv           The driver's structure.
 * @return              True if the driver's task is successfully spawned, false
 *                      otherwise.
 */
bool start_driver(driver_t *drv)
{
        int rc;

        assert(fibril_mutex_is_locked(&drv->driver_mutex));
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "start_driver(drv=\"%s\")", drv->name);
        
        rc = task_spawnl(NULL, drv->binary_path, drv->binary_path, NULL);
        if (rc != EOK) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Spawning driver `%s' (%s) failed: %s.",
                    drv->name, drv->binary_path, str_error(rc));
                return false;
        }
        
        drv->state = DRIVER_STARTING;
        return true;
}

/** Find device driver in the list of device drivers.
 *
 * @param drv_list      The list of device drivers.
 * @param drv_name      The name of the device driver which is searched.
 * @return              The device driver of the specified name, if it is in the
 *                      list, NULL otherwise.
 */
driver_t *find_driver(driver_list_t *drv_list, const char *drv_name)
{
        driver_t *res = NULL;
        
        fibril_mutex_lock(&drv_list->drivers_mutex);
        
        list_foreach(drv_list->drivers, drivers, driver_t, drv) {
                if (str_cmp(drv->name, drv_name) == 0) {
                        res = drv;
                        break;
                }
        }
        
        fibril_mutex_unlock(&drv_list->drivers_mutex);
        
        return res;
}

/** Notify driver about the devices to which it was assigned.
 *
 * @param driver        The driver to which the devices are passed.
 */
static void pass_devices_to_driver(driver_t *driver, dev_tree_t *tree)
{
        dev_node_t *dev;
        link_t *link;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "pass_devices_to_driver(driver=\"%s\")",
            driver->name);

        fibril_mutex_lock(&driver->driver_mutex);

        /*
         * Go through devices list as long as there is some device
         * that has not been passed to the driver.
         */
        link = driver->devices.head.next;
        while (link != &driver->devices.head) {
                dev = list_get_instance(link, dev_node_t, driver_devices);
                fibril_rwlock_write_lock(&tree->rwlock);
                
                if (dev->passed_to_driver) {
                        fibril_rwlock_write_unlock(&tree->rwlock);
                        link = link->next;
                        continue;
                }

                log_msg(LOG_DEFAULT, LVL_DEBUG, "pass_devices_to_driver: dev->refcnt=%d\n",
                    (int)atomic_get(&dev->refcnt));
                dev_add_ref(dev);

                /*
                 * Unlock to avoid deadlock when adding device
                 * handled by itself.
                 */
                fibril_mutex_unlock(&driver->driver_mutex);
                fibril_rwlock_write_unlock(&tree->rwlock);

                add_device(driver, dev, tree);

                dev_del_ref(dev);

                /*
                 * Lock again as we will work with driver's
                 * structure.
                 */
                fibril_mutex_lock(&driver->driver_mutex);

                /*
                 * Restart the cycle to go through all devices again.
                 */
                link = driver->devices.head.next;
        }

        /*
         * Once we passed all devices to the driver, we need to mark the
         * driver as running.
         * It is vital to do it here and inside critical section.
         *
         * If we would change the state earlier, other devices added to
         * the driver would be added to the device list and started
         * immediately and possibly started here as well.
         */
        log_msg(LOG_DEFAULT, LVL_DEBUG, "Driver `%s' enters running state.", driver->name);
        driver->state = DRIVER_RUNNING;

        fibril_mutex_unlock(&driver->driver_mutex);
}

/** Finish the initialization of a driver after it has succesfully started
 * and after it has registered itself by the device manager.
 *
 * Pass devices formerly matched to the driver to the driver and remember the
 * driver is running and fully functional now.
 *
 * @param driver        The driver which registered itself as running by the
 *                      device manager.
 */
void initialize_running_driver(driver_t *driver, dev_tree_t *tree)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "initialize_running_driver(driver=\"%s\")",
            driver->name);
        
        /*
         * Pass devices which have been already assigned to the driver to the
         * driver.
         */
        pass_devices_to_driver(driver, tree);
}

/** Initialize device driver structure.
 *
 * @param drv           The device driver structure.
 */
void init_driver(driver_t *drv)
{
        assert(drv != NULL);

        memset(drv, 0, sizeof(driver_t));
        list_initialize(&drv->match_ids.ids);
        list_initialize(&drv->devices);
        fibril_mutex_initialize(&drv->driver_mutex);
        drv->sess = NULL;
}

/** Device driver structure clean-up.
 *
 * @param drv           The device driver structure.
 */
void clean_driver(driver_t *drv)
{
        assert(drv != NULL);

        free(drv->name);
        free(drv->binary_path);

        clean_match_ids(&drv->match_ids);

        init_driver(drv);
}

/** Delete device driver structure.
 *
 * @param drv           The device driver structure.
 */
void delete_driver(driver_t *drv)
{
        assert(drv != NULL);
        
        clean_driver(drv);
        free(drv);
}

/** Create loc path and name for the function. */
void loc_register_tree_function(fun_node_t *fun, dev_tree_t *tree)
{
        char *loc_pathname = NULL;
        char *loc_name = NULL;
        
        assert(fibril_rwlock_is_locked(&tree->rwlock));
        
        asprintf(&loc_name, "%s", fun->pathname);
        if (loc_name == NULL)
                return;
        
        replace_char(loc_name, '/', LOC_SEPARATOR);
        
        asprintf(&loc_pathname, "%s/%s", LOC_DEVICE_NAMESPACE,
            loc_name);
        if (loc_pathname == NULL) {
                free(loc_name);
                return;
        }
        
        loc_service_register_with_iface(loc_pathname,
            &fun->service_id, DEVMAN_CONNECT_FROM_LOC);
        
        tree_add_loc_function(tree, fun);
        
        free(loc_name);
        free(loc_pathname);
}

/** Pass a device to running driver.
 *
 * @param drv           The driver's structure.
 * @param node          The device's node in the device tree.
 */
void add_device(driver_t *drv, dev_node_t *dev, dev_tree_t *tree)
{
        /*
         * We do not expect to have driver's mutex locked as we do not
         * access any structures that would affect driver_t.
         */
        log_msg(LOG_DEFAULT, LVL_DEBUG, "add_device(drv=\"%s\", dev=\"%s\")",
            drv->name, dev->pfun->name);
        
        /* Send the device to the driver. */
        devman_handle_t parent_handle;
        if (dev->pfun) {
                parent_handle = dev->pfun->handle;
        } else {
                parent_handle = 0;
        }
        
        async_exch_t *exch = async_exchange_begin(drv->sess);
        
        ipc_call_t answer;
        aid_t req = async_send_2(exch, DRIVER_DEV_ADD, dev->handle,
            parent_handle, &answer);
        
        /* Send the device name to the driver. */
        sysarg_t rc = async_data_write_start(exch, dev->pfun->name,
            str_size(dev->pfun->name) + 1);
        
        async_exchange_end(exch);
        
        if (rc != EOK) {
                /* TODO handle error */
        }

        /* Wait for answer from the driver. */
        async_wait_for(req, &rc);

        switch(rc) {
        case EOK:
                dev->state = DEVICE_USABLE;
                break;
        case ENOENT:
                dev->state = DEVICE_NOT_PRESENT;
                break;
        default:
                dev->state = DEVICE_INVALID;
                break;
        }
        
        dev->passed_to_driver = true;

        return;
}

/** Find suitable driver for a device and assign the driver to it.
 *
 * @param node          The device node of the device in the device tree.
 * @param drivers_list  The list of available drivers.
 * @return              True if the suitable driver is found and
 *                      successfully assigned to the device, false otherwise.
 */
bool assign_driver(dev_node_t *dev, driver_list_t *drivers_list,
    dev_tree_t *tree)
{
        assert(dev != NULL);
        assert(drivers_list != NULL);
        assert(tree != NULL);
        
        /*
         * Find the driver which is the most suitable for handling this device.
         */
        driver_t *drv = find_best_match_driver(drivers_list, dev);
        if (drv == NULL) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "No driver found for device `%s'.",
                    dev->pfun->pathname);
                return false;
        }
        
        /* Attach the driver to the device. */
        attach_driver(tree, dev, drv);
        
        fibril_mutex_lock(&drv->driver_mutex);
        if (drv->state == DRIVER_NOT_STARTED) {
                /* Start the driver. */
                start_driver(drv);
        }
        bool is_running = drv->state == DRIVER_RUNNING;
        fibril_mutex_unlock(&drv->driver_mutex);

        /* Notify the driver about the new device. */
        if (is_running)
                add_device(drv, dev, tree);
        
        fibril_mutex_lock(&drv->driver_mutex);
        fibril_mutex_unlock(&drv->driver_mutex);

        fibril_rwlock_write_lock(&tree->rwlock);
        if (dev->pfun != NULL) {
                dev->pfun->state = FUN_ON_LINE;
        }
        fibril_rwlock_write_unlock(&tree->rwlock);
        return true;
}

int driver_dev_remove(dev_tree_t *tree, dev_node_t *dev)
{
        async_exch_t *exch;
        sysarg_t retval;
        driver_t *drv;
        devman_handle_t handle;
        
        assert(dev != NULL);
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "driver_dev_remove(%p)", dev);
        
        fibril_rwlock_read_lock(&tree->rwlock);
        drv = dev->drv;
        handle = dev->handle;
        fibril_rwlock_read_unlock(&tree->rwlock);
        
        exch = async_exchange_begin(drv->sess);
        retval = async_req_1_0(exch, DRIVER_DEV_REMOVE, handle);
        async_exchange_end(exch);
        
        return retval;
}

int driver_dev_gone(dev_tree_t *tree, dev_node_t *dev)
{
        async_exch_t *exch;
        sysarg_t retval;
        driver_t *drv;
        devman_handle_t handle;
        
        assert(dev != NULL);
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "driver_dev_gone(%p)", dev);
        
        fibril_rwlock_read_lock(&tree->rwlock);
        drv = dev->drv;
        handle = dev->handle;
        fibril_rwlock_read_unlock(&tree->rwlock);
        
        exch = async_exchange_begin(drv->sess);
        retval = async_req_1_0(exch, DRIVER_DEV_GONE, handle);
        async_exchange_end(exch);
        
        return retval;
}

int driver_fun_online(dev_tree_t *tree, fun_node_t *fun)
{
        async_exch_t *exch;
        sysarg_t retval;
        driver_t *drv;
        devman_handle_t handle;
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "driver_fun_online(%p)", fun);

        fibril_rwlock_read_lock(&tree->rwlock);
        
        if (fun->dev == NULL) {
                /* XXX root function? */
                fibril_rwlock_read_unlock(&tree->rwlock);
                return EINVAL;
        }
        
        drv = fun->dev->drv;
        handle = fun->handle;
        fibril_rwlock_read_unlock(&tree->rwlock);
        
        exch = async_exchange_begin(drv->sess);
        retval = async_req_1_0(exch, DRIVER_FUN_ONLINE, handle);
        loc_exchange_end(exch);
        
        return retval;
}

int driver_fun_offline(dev_tree_t *tree, fun_node_t *fun)
{
        async_exch_t *exch;
        sysarg_t retval;
        driver_t *drv;
        devman_handle_t handle;
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "driver_fun_offline(%p)", fun);

        fibril_rwlock_read_lock(&tree->rwlock);
        if (fun->dev == NULL) {
                /* XXX root function? */
                fibril_rwlock_read_unlock(&tree->rwlock);
                return EINVAL;
        }
        
        drv = fun->dev->drv;
        handle = fun->handle;
        fibril_rwlock_read_unlock(&tree->rwlock);
        
        exch = async_exchange_begin(drv->sess);
        retval = async_req_1_0(exch, DRIVER_FUN_OFFLINE, handle);
        loc_exchange_end(exch);
        
        return retval;

}

/** Initialize the device tree.
 *
 * Create root device node of the tree and assign driver to it.
 *
 * @param tree          The device tree.
 * @param drivers_list  the list of available drivers.
 * @return              True on success, false otherwise.
 */
bool init_device_tree(dev_tree_t *tree, driver_list_t *drivers_list)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "init_device_tree()");
        
        tree->current_handle = 0;
        
        hash_table_create(&tree->devman_devices, 0, 0, &devman_devices_ops);
        hash_table_create(&tree->devman_functions, 0, 0, &devman_functions_ops);
        hash_table_create(&tree->loc_functions, 0, 0, &loc_devices_ops);
        
        fibril_rwlock_initialize(&tree->rwlock);
        
        /* Create root function and root device and add them to the device tree. */
        if (!create_root_nodes(tree))
                return false;
    
        /* Find suitable driver and start it. */
        dev_node_t *rdev = tree->root_node->child;
        dev_add_ref(rdev);
        int rc = assign_driver(rdev, drivers_list, tree);
        dev_del_ref(rdev);
        
        return rc;
}

/* Device nodes */

/** Create a new device node.
 *
 * @return              A device node structure.
 */
dev_node_t *create_dev_node(void)
{
        dev_node_t *dev;
        
        dev = calloc(1, sizeof(dev_node_t));
        if (dev == NULL)
                return NULL;
        
        atomic_set(&dev->refcnt, 0);
        list_initialize(&dev->functions);
        link_initialize(&dev->driver_devices);
        
        return dev;
}

/** Delete a device node.
 *
 * @param node          The device node structure.
 */
void delete_dev_node(dev_node_t *dev)
{
        assert(list_empty(&dev->functions));
        assert(dev->pfun == NULL);
        assert(dev->drv == NULL);
        
        free(dev);
}

/** Increase device node reference count.
 *
 * @param dev   Device node
 */
void dev_add_ref(dev_node_t *dev)
{
        atomic_inc(&dev->refcnt);
}

/** Decrease device node reference count.
 *
 * When the count drops to zero the device node is freed.
 *
 * @param dev   Device node
 */
void dev_del_ref(dev_node_t *dev)
{
        if (atomic_predec(&dev->refcnt) == 0)
                delete_dev_node(dev);
}

/** Find the device node structure of the device witch has the specified handle.
 *
 * @param tree          The device tree where we look for the device node.
 * @param handle        The handle of the device.
 * @return              The device node.
 */
dev_node_t *find_dev_node_no_lock(dev_tree_t *tree, devman_handle_t handle)
{
        assert(fibril_rwlock_is_locked(&tree->rwlock));
        
        ht_link_t *link = hash_table_find(&tree->devman_devices, &handle);
        if (link == NULL)
                return NULL;
        
        return hash_table_get_inst(link, dev_node_t, devman_dev);
}

/** Find the device node structure of the device witch has the specified handle.
 *
 * @param tree          The device tree where we look for the device node.
 * @param handle        The handle of the device.
 * @return              The device node.
 */
dev_node_t *find_dev_node(dev_tree_t *tree, devman_handle_t handle)
{
        dev_node_t *dev = NULL;
        
        fibril_rwlock_read_lock(&tree->rwlock);
        dev = find_dev_node_no_lock(tree, handle);
        if (dev != NULL)
                dev_add_ref(dev);
        
        fibril_rwlock_read_unlock(&tree->rwlock);
        
        return dev;
}

/** Get list of device functions. */
int dev_get_functions(dev_tree_t *tree, dev_node_t *dev,
    devman_handle_t *hdl_buf, size_t buf_size, size_t *act_size)
{
        size_t act_cnt;
        size_t buf_cnt;

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

        buf_cnt = buf_size / sizeof(devman_handle_t);

        act_cnt = list_count(&dev->functions);
        *act_size = act_cnt * sizeof(devman_handle_t);

        if (buf_size % sizeof(devman_handle_t) != 0)
                return EINVAL;

        size_t pos = 0;
        list_foreach(dev->functions, dev_functions, fun_node_t, fun) {
                if (pos < buf_cnt) {
                        hdl_buf[pos] = fun->handle;
                }

                pos++;
        }

        return EOK;
}


/* 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;
        atomic_set(&fun->refcnt, 0);
        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)
{
        atomic_inc(&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 (atomic_predec(&fun->refcnt) == 0)
                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.).
 */
static 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;
}

/** Insert new device into device tree.
 *
 * @param tree          The device tree.
 * @param dev           The newly added device node.
 * @param pfun          The parent function node.
 *
 * @return              True on success, false otherwise (insufficient resources
 *                      etc.).
 */
bool insert_dev_node(dev_tree_t *tree, dev_node_t *dev, fun_node_t *pfun)
{
        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "insert_dev_node(dev=%p, pfun=%p [\"%s\"])",
            dev, pfun, pfun->pathname);

        /* Add the node to the handle-to-node map. */
        dev->handle = ++tree->current_handle;
        hash_table_insert(&tree->devman_devices, &dev->devman_dev);

        /* Add the node to the list of its parent's children. */
        dev->pfun = pfun;
        pfun->child = dev;
        
        return true;
}

/** Remove device from device tree.
 *
 * @param tree          Device tree
 * @param dev           Device node
 */
void remove_dev_node(dev_tree_t *tree, dev_node_t *dev)
{
        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
        
        log_msg(LOG_DEFAULT, LVL_DEBUG, "remove_dev_node(dev=%p)", dev);
        
        /* Remove node from the handle-to-node map. */
        hash_table_remove(&tree->devman_devices, &dev->handle);
        
        /* Unlink from parent function. */
        dev->pfun->child = NULL;
        dev->pfun = NULL;
        
        dev->state = DEVICE_REMOVED;
}


/** Insert new function into device tree.
 *
 * @param tree          The device tree.
 * @param fun           The newly added function node. 
 * @param fun_name      The name of the newly added function.
 * @param dev           Owning device node.
 *
 * @return              True on success, false otherwise (insufficient resources
 *                      etc.).
 */
bool insert_fun_node(dev_tree_t *tree, fun_node_t *fun, char *fun_name,
    dev_node_t *dev)
{
        fun_node_t *pfun;
        
        assert(fun_name != NULL);
        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
        
        /*
         * The root function is a special case, it does not belong to any
         * device so for the root function dev == NULL.
         */
        pfun = (dev != NULL) ? dev->pfun : NULL;
        
        fun->name = fun_name;
        if (!set_fun_path(tree, fun, pfun)) {
                return false;
        }
        
        /* Add the node to the handle-to-node map. */
        fun->handle = ++tree->current_handle;
        hash_table_insert(&tree->devman_functions, &fun->devman_fun);

        /* Add the node to the list of its parent's children. */
        fun->dev = dev;
        if (dev != NULL)
                list_append(&fun->dev_functions, &dev->functions);
        
        return true;
}

/** Remove function from device tree.
 *
 * @param tree          Device tree
 * @param node          Function node to remove
 */
void remove_fun_node(dev_tree_t *tree, fun_node_t *fun)
{
        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
        
        /* Remove the node from the handle-to-node map. */
        hash_table_remove(&tree->devman_functions, &fun->handle);
        
        /* Remove the node from the list of its parent's children. */
        if (fun->dev != NULL)
                list_remove(&fun->dev_functions);
        
        fun->dev = NULL;
        fun->state = FUN_REMOVED;
}

/** 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);
}

/* loc devices */

fun_node_t *find_loc_tree_function(dev_tree_t *tree, service_id_t service_id)
{
        fun_node_t *fun = NULL;
        
        fibril_rwlock_read_lock(&tree->rwlock);
        ht_link_t *link = hash_table_find(&tree->loc_functions, &service_id);
        if (link != NULL) {
                fun = hash_table_get_inst(link, fun_node_t, loc_fun);
                fun_add_ref(fun);
        }
        fibril_rwlock_read_unlock(&tree->rwlock);
        
        return fun;
}

void tree_add_loc_function(dev_tree_t *tree, fun_node_t *fun)
{
        assert(fibril_rwlock_is_write_locked(&tree->rwlock));
        
        hash_table_insert(&tree->loc_functions, &fun->loc_fun);
}

/** @}
 */