source: mainline/uspace/srv/devman/main.c@ 422722e

/*
 * 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.
 */

/**
 * @defgroup devman Device manager.
 * @brief HelenOS device manager.
 * @{
 */

/** @file
 */

#include <inttypes.h>
#include <assert.h>
#include <ipc/services.h>
#include <ns.h>
#include <async.h>
#include <stdio.h>
#include <errno.h>
#include <str_error.h>
#include <bool.h>
#include <fibril_synch.h>
#include <stdlib.h>
#include <str.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <ctype.h>
#include <io/log.h>
#include <ipc/devman.h>
#include <ipc/driver.h>
#include <thread.h>
#include <loc.h>

#include "devman.h"

#define DRIVER_DEFAULT_STORE  "/drv"

static driver_list_t drivers_list;
static dev_tree_t device_tree;

static int init_running_drv(void *drv);

/** Register running driver. */
static driver_t *devman_driver_register(ipc_callid_t callid, ipc_call_t *call)
{
        driver_t *driver = NULL;
        char *drv_name = NULL;

        log_msg(LVL_DEBUG, "devman_driver_register");
        
        /* Get driver name. */
        int rc = async_data_write_accept((void **) &drv_name, true, 0, 0, 0, 0);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return NULL;
        }

        log_msg(LVL_DEBUG, "The `%s' driver is trying to register.",
            drv_name);
        
        /* Find driver structure. */
        driver = find_driver(&drivers_list, drv_name);
        if (driver == NULL) {
                log_msg(LVL_ERROR, "No driver named `%s' was found.", drv_name);
                free(drv_name);
                drv_name = NULL;
                async_answer_0(callid, ENOENT);
                return NULL;
        }
        
        free(drv_name);
        drv_name = NULL;
        
        fibril_mutex_lock(&driver->driver_mutex);
        
        if (driver->sess) {
                /* We already have a connection to the driver. */
                log_msg(LVL_ERROR, "Driver '%s' already started.\n",
                    driver->name);
                fibril_mutex_unlock(&driver->driver_mutex);
                async_answer_0(callid, EEXISTS);
                return NULL;
        }
        
        switch (driver->state) {
        case DRIVER_NOT_STARTED:
                /* Somebody started the driver manually. */
                log_msg(LVL_NOTE, "Driver '%s' started manually.\n",
                    driver->name);
                driver->state = DRIVER_STARTING;
                break;
        case DRIVER_STARTING:
                /* The expected case */
                break;
        case DRIVER_RUNNING:
                /* Should not happen since we do not have a connected session */
                assert(false);
        }
        
        /* Create connection to the driver. */
        log_msg(LVL_DEBUG, "Creating connection to the `%s' driver.",
            driver->name);
        driver->sess = async_callback_receive(EXCHANGE_PARALLEL);
        if (!driver->sess) {
                fibril_mutex_unlock(&driver->driver_mutex);
                async_answer_0(callid, ENOTSUP);
                return NULL;
        }
        /* FIXME: Work around problem with callback sessions */
        async_sess_args_set(driver->sess, DRIVER_DEVMAN, 0, 0);
        
        log_msg(LVL_NOTE,
            "The `%s' driver was successfully registered as running.",
            driver->name);
        
        /*
         * Initialize the driver as running (e.g. pass assigned devices to it)
         * in a separate fibril; the separate fibril is used to enable the
         * driver to use devman service during the driver's initialization.
         */
        fid_t fid = fibril_create(init_running_drv, driver);
        if (fid == 0) {
                log_msg(LVL_ERROR, "Failed to create initialization fibril " \
                    "for driver `%s'.", driver->name);
                fibril_mutex_unlock(&driver->driver_mutex);
                async_answer_0(callid, ENOMEM);
                return NULL;
        }
        
        fibril_add_ready(fid);
        fibril_mutex_unlock(&driver->driver_mutex);
        
        async_answer_0(callid, EOK);
        return driver;
}

/** Receive device match ID from the device's parent driver and add it to the
 * list of devices match ids.
 *
 * @param match_ids     The list of the device's match ids.
 * @return              Zero on success, negative error code otherwise.
 */
static int devman_receive_match_id(match_id_list_t *match_ids)
{
        match_id_t *match_id = create_match_id();
        ipc_callid_t callid;
        ipc_call_t call;
        int rc = 0;
        
        callid = async_get_call(&call);
        if (DEVMAN_ADD_MATCH_ID != IPC_GET_IMETHOD(call)) {
                log_msg(LVL_ERROR, 
                    "Invalid protocol when trying to receive match id.");
                async_answer_0(callid, EINVAL); 
                delete_match_id(match_id);
                return EINVAL;
        }
        
        if (match_id == NULL) {
                log_msg(LVL_ERROR, "Failed to allocate match id.");
                async_answer_0(callid, ENOMEM);
                return ENOMEM;
        }
        
        async_answer_0(callid, EOK);
        
        match_id->score = IPC_GET_ARG1(call);
        
        char *match_id_str;
        rc = async_data_write_accept((void **) &match_id_str, true, 0, 0, 0, 0);
        match_id->id = match_id_str;
        if (rc != EOK) {
                delete_match_id(match_id);
                log_msg(LVL_ERROR, "Failed to receive match id string: %s.",
                    str_error(rc));
                return rc;
        }
        
        list_append(&match_id->link, &match_ids->ids);
        
        log_msg(LVL_DEBUG, "Received match id `%s', score %d.",
            match_id->id, match_id->score);
        return rc;
}

/** Receive device match IDs from the device's parent driver and add them to the
 * list of devices match ids.
 *
 * @param match_count   The number of device's match ids to be received.
 * @param match_ids     The list of the device's match ids.
 * @return              Zero on success, negative error code otherwise.
 */
static int devman_receive_match_ids(sysarg_t match_count,
    match_id_list_t *match_ids)
{
        int ret = EOK;
        size_t i;
        
        for (i = 0; i < match_count; i++) {
                if (EOK != (ret = devman_receive_match_id(match_ids)))
                        return ret;
        }
        return ret;
}

static int assign_driver_fibril(void *arg)
{
        dev_node_t *dev_node = (dev_node_t *) arg;
        assign_driver(dev_node, &drivers_list, &device_tree);
        return EOK;
}

/** Handle function registration.
 *
 * Child devices are registered by their parent's device driver.
 */
static void devman_add_function(ipc_callid_t callid, ipc_call_t *call)
{
        fun_type_t ftype = (fun_type_t) IPC_GET_ARG1(*call);
        devman_handle_t dev_handle = IPC_GET_ARG2(*call);
        sysarg_t match_count = IPC_GET_ARG3(*call);
        dev_tree_t *tree = &device_tree;
        
        fibril_rwlock_write_lock(&tree->rwlock);

        dev_node_t *dev = NULL;
        dev_node_t *pdev = find_dev_node_no_lock(&device_tree, dev_handle);
        
        if (pdev == NULL) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                async_answer_0(callid, ENOENT);
                return;
        }
        
        if (ftype != fun_inner && ftype != fun_exposed) {
                /* Unknown function type */
                log_msg(LVL_ERROR, 
                    "Unknown function type %d provided by driver.",
                    (int) ftype);

                fibril_rwlock_write_unlock(&tree->rwlock);
                async_answer_0(callid, EINVAL);
                return;
        }
        
        char *fun_name = NULL;
        int rc = async_data_write_accept((void **)&fun_name, true, 0, 0, 0, 0);
        if (rc != EOK) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                async_answer_0(callid, rc);
                return;
        }
        
        /* Check that function with same name is not there already. */
        if (find_fun_node_in_device(pdev, fun_name) != NULL) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                async_answer_0(callid, EEXISTS);
                printf(NAME ": Warning, driver tried to register `%s' twice.\n",
                    fun_name);
                free(fun_name);
                return;
        }
        
        fun_node_t *fun = create_fun_node();
        fun->ftype = ftype;
        
        if (!insert_fun_node(&device_tree, fun, fun_name, pdev)) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                delete_fun_node(fun);
                async_answer_0(callid, ENOMEM);
                return;
        }

        if (ftype == fun_inner) {
                dev = create_dev_node();
                if (dev == NULL) {
                        fibril_rwlock_write_unlock(&tree->rwlock);
                        delete_fun_node(fun);
                        async_answer_0(callid, ENOMEM);
                        return;
                }

                insert_dev_node(tree, dev, fun);
        }

        fibril_rwlock_write_unlock(&tree->rwlock);
        
        log_msg(LVL_DEBUG, "devman_add_function(fun=\"%s\")", fun->pathname);
        
        devman_receive_match_ids(match_count, &fun->match_ids);

        if (ftype == fun_inner) {
                assert(dev != NULL);
                /*
                 * 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) {
                        /*
                         * Fallback in case we are out of memory.
                         * Probably not needed as we will die soon anyway ;-).
                         */
                        (void) assign_driver_fibril(fun);
                } else {
                        fibril_add_ready(assign_fibril);
                }
        } else {
                loc_register_tree_function(fun, tree);
        }
        
        /* Return device handle to parent's driver. */
        async_answer_1(callid, EOK, fun->handle);
}

static void devman_add_function_to_cat(ipc_callid_t callid, ipc_call_t *call)
{
        devman_handle_t handle = IPC_GET_ARG1(*call);
        category_id_t cat_id;
        int rc;
        
        /* Get category name. */
        char *cat_name;
        rc = async_data_write_accept((void **) &cat_name, true,
            0, 0, 0, 0);
        if (rc != EOK) {
                async_answer_0(callid, rc);
                return;
        }       
        
        fun_node_t *fun = find_fun_node(&device_tree, handle);
        if (fun == NULL) {
                async_answer_0(callid, ENOENT);
                return;
        }
        
        rc = loc_category_get_id(cat_name, &cat_id, IPC_FLAG_BLOCKING);
        if (rc == EOK) {
                loc_service_add_to_cat(fun->service_id, cat_id);
        } else {
                log_msg(LVL_ERROR, "Failed adding function `%s' to category "
                    "`%s'.", fun->pathname, cat_name);
        }
        
        log_msg(LVL_NOTE, "Function `%s' added to category `%s'.",
            fun->pathname, cat_name);

        async_answer_0(callid, EOK);
}

/** Remove function. */
static void devman_remove_function(ipc_callid_t callid, ipc_call_t *call)
{
        devman_handle_t fun_handle = IPC_GET_ARG1(*call);
        dev_tree_t *tree = &device_tree;
        int rc;
        
        fibril_rwlock_write_lock(&tree->rwlock);
        
        fun_node_t *fun = find_fun_node_no_lock(&device_tree, fun_handle);
        if (fun == NULL) {
                fibril_rwlock_write_unlock(&tree->rwlock);
                async_answer_0(callid, ENOENT);
                return;
        }
        
        log_msg(LVL_DEBUG, "devman_remove_function(fun='%s')", fun->pathname);
        
        if (fun->ftype == fun_inner) {
                /* Handle possible descendants */
                /* TODO */
                log_msg(LVL_WARN, "devman_remove_function(): not handling "
                    "descendants\n");
        } else {
                /* Unregister from location service */
                rc = loc_service_unregister(fun->service_id);
                if (rc != EOK) {
                        log_msg(LVL_ERROR, "Failed unregistering tree service.");
                        fibril_rwlock_write_unlock(&tree->rwlock);
                        async_answer_0(callid, EIO);
                        return;
                }
        }
        
        remove_fun_node(&device_tree, fun);
        fibril_rwlock_write_unlock(&tree->rwlock);
        delete_fun_node(fun);
        
        log_msg(LVL_DEBUG, "devman_remove_function() succeeded.");
        async_answer_0(callid, EOK);
}

/** Initialize driver which has registered itself as running and ready.
 *
 * The initialization is done in a separate fibril to avoid deadlocks (if the
 * driver needed to be served by devman during the driver's initialization).
 */
static int init_running_drv(void *drv)
{
        driver_t *driver = (driver_t *) drv;
        
        initialize_running_driver(driver, &device_tree);
        log_msg(LVL_DEBUG, "The `%s` driver was successfully initialized.",
            driver->name);
        return 0;
}

/** Function for handling connections from a driver to the device manager. */
static void devman_connection_driver(ipc_callid_t iid, ipc_call_t *icall)
{
        client_t *client;
        driver_t *driver;
        
        /* Accept the connection. */
        async_answer_0(iid, EOK);
        
        client = async_get_client_data();
        if (client == NULL) {
                log_msg(LVL_ERROR, "Failed to allocate client data.");
                return;
        }
        
        while (true) {
                ipc_call_t call;
                ipc_callid_t callid = async_get_call(&call);
                
                if (!IPC_GET_IMETHOD(call))
                        break;
                
                if (IPC_GET_IMETHOD(call) != DEVMAN_DRIVER_REGISTER) {
                        fibril_mutex_lock(&client->mutex);
                        driver = client->driver;
                        fibril_mutex_unlock(&client->mutex);
                        if (driver == NULL) {
                                /* First call must be to DEVMAN_DRIVER_REGISTER */
                                async_answer_0(callid, ENOTSUP);
                                continue;
                        }
                }
                
                switch (IPC_GET_IMETHOD(call)) {
                case DEVMAN_DRIVER_REGISTER:
                        fibril_mutex_lock(&client->mutex);
                        if (client->driver != NULL) {
                                fibril_mutex_unlock(&client->mutex);
                                async_answer_0(callid, EINVAL);
                                continue;
                        }
                        client->driver = devman_driver_register(callid, &call);
                        fibril_mutex_unlock(&client->mutex);
                        break;
                case DEVMAN_ADD_FUNCTION:
                        devman_add_function(callid, &call);
                        break;
                case DEVMAN_ADD_DEVICE_TO_CATEGORY:
                        devman_add_function_to_cat(callid, &call);
                        break;
                case DEVMAN_REMOVE_FUNCTION:
                        devman_remove_function(callid, &call);
                        break;
                default:
                        async_answer_0(callid, EINVAL); 
                        break;
                }
        }
}

/** Find handle for the device instance identified by the device's path in the
 * device tree. */
static void devman_function_get_handle(ipc_callid_t iid, ipc_call_t *icall)
{
        char *pathname;
        
        int rc = async_data_write_accept((void **) &pathname, true, 0, 0, 0, 0);
        if (rc != EOK) {
                async_answer_0(iid, rc);
                return;
        }
        
        fun_node_t *fun = find_fun_node_by_path(&device_tree, pathname);
        
        free(pathname);

        if (fun == NULL) {
                async_answer_0(iid, ENOENT);
                return;
        }

        async_answer_1(iid, EOK, fun->handle);
}

/** Get device name. */
static void devman_fun_get_name(ipc_callid_t iid, ipc_call_t *icall)
{
        devman_handle_t handle = IPC_GET_ARG1(*icall);

        fun_node_t *fun = find_fun_node(&device_tree, handle);
        if (fun == NULL) {
                async_answer_0(iid, ENOMEM);
                return;
        }

        ipc_callid_t data_callid;
        size_t data_len;
        if (!async_data_read_receive(&data_callid, &data_len)) {
                async_answer_0(iid, EINVAL);
                return;
        }

        void *buffer = malloc(data_len);
        if (buffer == NULL) {
                async_answer_0(data_callid, ENOMEM);
                async_answer_0(iid, ENOMEM);
                return;
        }

        size_t sent_length = str_size(fun->name);
        if (sent_length > data_len) {
                sent_length = data_len;
        }

        async_data_read_finalize(data_callid, fun->name, sent_length);
        async_answer_0(iid, EOK);

        free(buffer);
}


/** Get device path. */
static void devman_fun_get_path(ipc_callid_t iid, ipc_call_t *icall)
{
        devman_handle_t handle = IPC_GET_ARG1(*icall);

        fun_node_t *fun = find_fun_node(&device_tree, handle);
        if (fun == NULL) {
                async_answer_0(iid, ENOMEM);
                return;
        }

        ipc_callid_t data_callid;
        size_t data_len;
        if (!async_data_read_receive(&data_callid, &data_len)) {
                async_answer_0(iid, EINVAL);
                return;
        }

        void *buffer = malloc(data_len);
        if (buffer == NULL) {
                async_answer_0(data_callid, ENOMEM);
                async_answer_0(iid, ENOMEM);
                return;
        }

        size_t sent_length = str_size(fun->pathname);
        if (sent_length > data_len) {
                sent_length = data_len;
        }

        async_data_read_finalize(data_callid, fun->pathname, sent_length);
        async_answer_0(iid, EOK);

        free(buffer);
}

static void devman_dev_get_functions(ipc_callid_t iid, ipc_call_t *icall)
{
        ipc_callid_t callid;
        size_t size;
        size_t act_size;
        int rc;
        
        if (!async_data_read_receive(&callid, &size)) {
                async_answer_0(callid, EREFUSED);
                async_answer_0(iid, EREFUSED);
                return;
        }
        
        fibril_rwlock_read_lock(&device_tree.rwlock);
        
        dev_node_t *dev = find_dev_node_no_lock(&device_tree,
            IPC_GET_ARG1(*icall));
        if (dev == NULL) {
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                async_answer_0(callid, ENOENT);
                async_answer_0(iid, ENOENT);
                return;
        }
        
        devman_handle_t *hdl_buf = (devman_handle_t *) malloc(size);
        if (hdl_buf == NULL) {
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                async_answer_0(callid, ENOMEM);
                async_answer_0(iid, ENOMEM);
                return;
        }
        
        rc = dev_get_functions(&device_tree, dev, hdl_buf, size, &act_size);
        if (rc != EOK) {
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                async_answer_0(callid, rc);
                async_answer_0(iid, rc);
                return;
        }
        
        fibril_rwlock_read_unlock(&device_tree.rwlock);
        
        sysarg_t retval = async_data_read_finalize(callid, hdl_buf, size);
        free(hdl_buf);
        
        async_answer_1(iid, retval, act_size);
}


/** Get handle for child device of a function. */
static void devman_fun_get_child(ipc_callid_t iid, ipc_call_t *icall)
{
        fun_node_t *fun;
        
        fibril_rwlock_read_lock(&device_tree.rwlock);
        
        fun = find_fun_node(&device_tree, IPC_GET_ARG1(*icall));
        if (fun == NULL) {
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                async_answer_0(iid, ENOENT);
                return;
        }
        
        if (fun->child == NULL) {
                fibril_rwlock_read_unlock(&device_tree.rwlock);
                async_answer_0(iid, ENOENT);
                return;
        }
        
        async_answer_1(iid, EOK, fun->child->handle);
        
        fibril_rwlock_read_unlock(&device_tree.rwlock);
}

/** Find handle for the function instance identified by its service ID. */
static void devman_fun_sid_to_handle(ipc_callid_t iid, ipc_call_t *icall)
{
        fun_node_t *fun;

        fun = find_loc_tree_function(&device_tree, IPC_GET_ARG1(*icall));
        
        if (fun == NULL) {
                async_answer_0(iid, ENOENT);
                return;
        }

        async_answer_1(iid, EOK, fun->handle);
}

/** Function for handling connections from a client to the device manager. */
static void devman_connection_client(ipc_callid_t iid, ipc_call_t *icall)
{
        /* Accept connection. */
        async_answer_0(iid, EOK);
        
        while (true) {
                ipc_call_t call;
                ipc_callid_t callid = async_get_call(&call);
                
                if (!IPC_GET_IMETHOD(call))
                        break;
                
                switch (IPC_GET_IMETHOD(call)) {
                case DEVMAN_DEVICE_GET_HANDLE:
                        devman_function_get_handle(callid, &call);
                        break;
                case DEVMAN_DEV_GET_FUNCTIONS:
                        devman_dev_get_functions(callid, &call);
                        break;
                case DEVMAN_FUN_GET_CHILD:
                        devman_fun_get_child(callid, &call);
                        break;
                case DEVMAN_FUN_GET_NAME:
                        devman_fun_get_name(callid, &call);
                        break;
                case DEVMAN_FUN_GET_PATH:
                        devman_fun_get_path(callid, &call);
                        break;
                case DEVMAN_FUN_SID_TO_HANDLE:
                        devman_fun_sid_to_handle(callid, &call);
                        break;
                default:
                        async_answer_0(callid, ENOENT);
                }
        }
}

static void devman_forward(ipc_callid_t iid, ipc_call_t *icall,
    bool drv_to_parent)
{
        devman_handle_t handle = IPC_GET_ARG2(*icall);
        devman_handle_t fwd_h;
        fun_node_t *fun = NULL;
        dev_node_t *dev = NULL;
        
        fun = find_fun_node(&device_tree, handle);
        if (fun == NULL)
                dev = find_dev_node(&device_tree, handle);
        else
                dev = fun->dev;

        /*
         * For a valid function to connect to we need a device. The root
         * function, for example, has no device and cannot be connected to.
         * This means @c dev needs to be valid regardless whether we are
         * connecting to a device or to a function.
         */
        if (dev == NULL) {
                log_msg(LVL_ERROR, "IPC forwarding failed - no device or "
                    "function with handle %" PRIun " was found.", handle);
                async_answer_0(iid, ENOENT);
                return;
        }

        if (fun == NULL && !drv_to_parent) {
                log_msg(LVL_ERROR, NAME ": devman_forward error - cannot "
                    "connect to handle %" PRIun ", refers to a device.",
                    handle);
                async_answer_0(iid, ENOENT);
                return;
        }
        
        driver_t *driver = NULL;
        
        if (drv_to_parent) {
                /* Connect to parent function of a device (or device function). */
                if (dev->pfun->dev != NULL)
                        driver = dev->pfun->dev->drv;
                fwd_h = dev->pfun->handle;
        } else if (dev->state == DEVICE_USABLE) {
                /* Connect to the specified function */
                driver = dev->drv;
                assert(driver != NULL);

                fwd_h = handle;
        }
        
        if (driver == NULL) {
                log_msg(LVL_ERROR, "IPC forwarding refused - " \
                    "the device %" PRIun " is not in usable state.", handle);
                async_answer_0(iid, ENOENT);
                return;
        }
        
        int method;
        if (drv_to_parent)
                method = DRIVER_DRIVER;
        else
                method = DRIVER_CLIENT;
        
        if (!driver->sess) {
                log_msg(LVL_ERROR,
                    "Could not forward to driver `%s'.", driver->name);
                async_answer_0(iid, EINVAL);
                return;
        }

        if (fun != NULL) {
                log_msg(LVL_DEBUG, 
                    "Forwarding request for `%s' function to driver `%s'.",
                    fun->pathname, driver->name);
        } else {
                log_msg(LVL_DEBUG, 
                    "Forwarding request for `%s' device to driver `%s'.",
                    dev->pfun->pathname, driver->name);
        }
        
        async_exch_t *exch = async_exchange_begin(driver->sess);
        async_forward_fast(iid, exch, method, fwd_h, 0, IPC_FF_NONE);
        async_exchange_end(exch);
}

/** Function for handling connections from a client forwarded by the location
 * service to the device manager. */
static void devman_connection_loc(ipc_callid_t iid, ipc_call_t *icall)
{
        service_id_t service_id = IPC_GET_ARG2(*icall);
        fun_node_t *fun;
        dev_node_t *dev;

        fun = find_loc_tree_function(&device_tree, service_id);
        
        if (fun == NULL || fun->dev->drv == NULL) {
                log_msg(LVL_WARN, "devman_connection_loc(): function "
                    "not found.\n");
                async_answer_0(iid, ENOENT);
                return;
        }
        
        dev = fun->dev;
        
        async_exch_t *exch = async_exchange_begin(dev->drv->sess);
        async_forward_fast(iid, exch, DRIVER_CLIENT, fun->handle, 0,
            IPC_FF_NONE);
        async_exchange_end(exch);
        
        log_msg(LVL_DEBUG,
            "Forwarding loc service request for `%s' function to driver `%s'.",
            fun->pathname, dev->drv->name);
}

/** Function for handling connections to device manager. */
static void devman_connection(ipc_callid_t iid, ipc_call_t *icall, void *arg)
{
        /* Select port. */
        switch ((sysarg_t) (IPC_GET_ARG1(*icall))) {
        case DEVMAN_DRIVER:
                devman_connection_driver(iid, icall);
                break;
        case DEVMAN_CLIENT:
                devman_connection_client(iid, icall);
                break;
        case DEVMAN_CONNECT_TO_DEVICE:
                /* Connect client to selected device. */
                devman_forward(iid, icall, false);
                break;
        case DEVMAN_CONNECT_FROM_LOC:
                /* Someone connected through loc node. */
                devman_connection_loc(iid, icall);
                break;
        case DEVMAN_CONNECT_TO_PARENTS_DEVICE:
                /* Connect client to selected device. */
                devman_forward(iid, icall, true);
                break;
        default:
                /* No such interface */
                async_answer_0(iid, ENOENT);
        }
}

static void *devman_client_data_create(void)
{
        client_t *client;
        
        client = calloc(1, sizeof(client_t));
        if (client == NULL)
                return NULL;
        
        fibril_mutex_initialize(&client->mutex);
        return client;
}

static void devman_client_data_destroy(void *data)
{
        free(data);
}

/** Initialize device manager internal structures. */
static bool devman_init(void)
{
        log_msg(LVL_DEBUG, "devman_init - looking for available drivers.");
        
        /* Initialize list of available drivers. */
        init_driver_list(&drivers_list);
        if (lookup_available_drivers(&drivers_list,
            DRIVER_DEFAULT_STORE) == 0) {
                log_msg(LVL_FATAL, "No drivers found.");
                return false;
        }

        log_msg(LVL_DEBUG, "devman_init - list of drivers has been initialized.");

        /* Create root device node. */
        if (!init_device_tree(&device_tree, &drivers_list)) {
                log_msg(LVL_FATAL, "Failed to initialize device tree.");
                return false;
        }

        /*
         * !!! devman_connection ... as the device manager is not a real loc
         * driver (it uses a completely different ipc protocol than an ordinary
         * loc driver) forwarding a connection from client to the devman by
         * location service would not work.
         */
        loc_server_register(NAME, devman_connection);
        
        return true;
}

int main(int argc, char *argv[])
{
        printf(NAME ": HelenOS Device Manager\n");

        if (log_init(NAME, LVL_WARN) != EOK) {
                printf(NAME ": Error initializing logging subsystem.\n");
                return -1;
        }

        if (!devman_init()) {
                log_msg(LVL_ERROR, "Error while initializing service.");
                return -1;
        }
        
        /* Set handlers for incoming connections. */
        async_set_client_data_constructor(devman_client_data_create);
        async_set_client_data_destructor(devman_client_data_destroy);
        async_set_client_connection(devman_connection);

        /* Register device manager at naming service. */
        if (service_register(SERVICE_DEVMAN) != EOK) {
                log_msg(LVL_ERROR, "Failed registering as a service.");
                return -1;
        }

        printf(NAME ": Accepting connections.\n");
        task_retval(0);
        async_manager();

        /* Never reached. */
        return 0;
}

/** @}
 */