source: mainline/uspace/lib/drv/generic/remote_char_dev.c@ d51838f

/*
 * 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 libdrv
 * @{
 */
/** @file
 */

#include <async.h>
#include <errno.h>
#include <macros.h>

#include "ops/char_dev.h"
#include "char_dev_iface.h"
#include "ddf/driver.h"

#define MAX_CHAR_RW_COUNT 256

/** Read to or write from device.
 *
 * Helper function to read to or write from a device
 * using its character interface.
 *
 * @param sess Session to the device.
 * @param buf  Buffer for the data read from or written to the device.
 * @param size Maximum size of data (in bytes) to be read or written.
 * @param read Read from the device if true, write to it otherwise.
 *
 * @return Non-negative number of bytes actually read from or
 *         written to the device on success, negative error number
 *         otherwise.
 *
 */
static ssize_t char_dev_rw(async_sess_t *sess, void *buf, size_t size, bool read)
{
        ipc_call_t answer;
        aid_t req;
        int ret;
        
        async_exch_t *exch = async_exchange_begin(sess);
        
        if (read) {
                req = async_send_1(exch, DEV_IFACE_ID(CHAR_DEV_IFACE),
                    CHAR_DEV_READ, &answer);
                ret = async_data_read_start(exch, buf, size);
        } else {
                req = async_send_1(exch, DEV_IFACE_ID(CHAR_DEV_IFACE),
                    CHAR_DEV_WRITE, &answer);
                ret = async_data_write_start(exch, buf, size);
        }
        
        async_exchange_end(exch);
        
        sysarg_t rc;
        if (ret != EOK) {
                async_wait_for(req, &rc);
                if (rc == EOK)
                        return (ssize_t) ret;
                
                return (ssize_t) rc;
        }
        
        async_wait_for(req, &rc);
        
        ret = (int) rc;
        if (ret != EOK)
                return (ssize_t) ret;
        
        return (ssize_t) IPC_GET_ARG1(answer);
}

/** Read from character device.
 *
 * @param sess Session to the device.
 * @param buf  Output buffer for the data read from the device.
 * @param size Maximum size (in bytes) of the data to be read.
 *
 * @return Non-negative number of bytes actually read from the
 *         device on success, negative error number otherwise.
 *
 */
ssize_t char_dev_read(async_sess_t *sess, void *buf, size_t size)
{
        return char_dev_rw(sess, buf, size, true);
}

/** Write to character device.
 *
 * @param sess Session to the device.
 * @param buf  Input buffer containg the data to be written to the
 *             device.
 * @param size Maximum size (in bytes) of the data to be written.
 *
 * @return Non-negative number of bytes actually written to the
 *         device on success, negative error number otherwise.
 *
 */
ssize_t char_dev_write(async_sess_t *sess, void *buf, size_t size)
{
        return char_dev_rw(sess, buf, size, false);
}

static void remote_char_read(ddf_fun_t *, void *, ipc_callid_t, ipc_call_t *);
static void remote_char_write(ddf_fun_t *, void *, ipc_callid_t, ipc_call_t *);

/** Remote character interface operations. */
static const remote_iface_func_ptr_t remote_char_dev_iface_ops[] = {
        [CHAR_DEV_READ] = remote_char_read,
        [CHAR_DEV_WRITE] = remote_char_write
};

/** Remote character interface structure.
 *
 * Interface for processing request from remote clients addressed to the
 * character interface.
 */
const remote_iface_t remote_char_dev_iface = {
        .method_count = ARRAY_SIZE(remote_char_dev_iface_ops),
        .methods = remote_char_dev_iface_ops
};

/** Process the read request from the remote client.
 *
 * Receive the read request's parameters from the remote client and pass them
 * to the local interface. Return the result of the operation processed by the
 * local interface to the remote client.
 *
 * @param fun           The function from which the data are read.
 * @param ops           The local ops structure.
 */
static void
remote_char_read(ddf_fun_t *fun, void *ops, ipc_callid_t callid,
    ipc_call_t *call)
{
        char_dev_ops_t *char_dev_ops = (char_dev_ops_t *) ops;
        ipc_callid_t cid;
        
        size_t len;
        if (!async_data_read_receive(&cid, &len)) {
                /* TODO handle protocol error. */
                async_answer_0(callid, EINVAL);
                return;
        }
        
        if (!char_dev_ops->read) {
                async_data_read_finalize(cid, NULL, 0);
                async_answer_0(callid, ENOTSUP);
                return;
        }
        
        if (len > MAX_CHAR_RW_COUNT)
                len = MAX_CHAR_RW_COUNT;
        
        char buf[MAX_CHAR_RW_COUNT];
        int ret = (*char_dev_ops->read)(fun, buf, len);
        
        if (ret < 0) {
                /* Some error occured. */
                async_data_read_finalize(cid, buf, 0);
                async_answer_0(callid, ret);
                return;
        }
        
        /* The operation was successful, return the number of data read. */
        async_data_read_finalize(cid, buf, ret);
        async_answer_1(callid, EOK, ret);
}

/** Process the write request from the remote client.
 *
 * Receive the write request's parameters from the remote client and pass them
 * to the local interface. Return the result of the operation processed by the
 * local interface to the remote client.
 *
 * @param fun           The function to which the data are written.
 * @param ops           The local ops structure.
 */
static void
remote_char_write(ddf_fun_t *fun, void *ops, ipc_callid_t callid,
    ipc_call_t *call)
{
        char_dev_ops_t *char_dev_ops = (char_dev_ops_t *) ops;
        ipc_callid_t cid;
        size_t len;
        
        if (!async_data_write_receive(&cid, &len)) {
                /* TODO handle protocol error. */
                async_answer_0(callid, EINVAL);
                return;
        }
        
        if (!char_dev_ops->write) {
                async_data_write_finalize(cid, NULL, 0);
                async_answer_0(callid, ENOTSUP);
                return;
        }
        
        if (len > MAX_CHAR_RW_COUNT)
                len = MAX_CHAR_RW_COUNT;
        
        char buf[MAX_CHAR_RW_COUNT];
        
        async_data_write_finalize(cid, buf, len);
        
        int ret = (*char_dev_ops->write)(fun, buf, len);
        if (ret < 0) {
                /* Some error occured. */
                async_answer_0(callid, ret);
        } else {
                /*
                 * The operation was successful, return the number of data
                 * written.
                 */
                async_answer_1(callid, EOK, ret);
        }
}

/**
 * @}
 */