source: mainline/uspace/lib/c/generic/device/char.c@ 96b02eb9

/*
 * 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 libc
 * @{
 */
/** @file
 */

#include <ipc/dev_iface.h>
#include <device/char.h>
#include <errno.h>
#include <async.h>
#include <malloc.h>
#include <stdio.h>

/** Read to or write from device.
 *
 * Helper function to read to or write from a device
 * using its character interface.
 *
 * @param dev_phone Phone to the device.
 * @param buf       Buffer for the data read
 *                  from or written to the device.
 * @param len       Maximum length of the data 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 rw_dev(int dev_phone, void *buf, size_t len, bool read)
{
        async_serialize_start();
        
        ipc_call_t answer;
        aid_t req;
        int ret;
        
        if (read) {
                req = async_send_1(dev_phone, DEV_IFACE_ID(CHAR_DEV_IFACE),
                    CHAR_READ_DEV, &answer);
                ret = async_data_read_start(dev_phone, buf, len);
        } else {
                req = async_send_1(dev_phone, DEV_IFACE_ID(CHAR_DEV_IFACE),
                    CHAR_WRITE_DEV, &answer);
                ret = async_data_write_start(dev_phone, buf, len);
        }
        
        sysarg_t rc;
        if (ret != EOK) {
                async_wait_for(req, &rc);
                async_serialize_end();
                if (rc == EOK)
                        return (ssize_t) ret;
                        
                return (ssize_t) rc;
        }
        
        async_wait_for(req, &rc);
        async_serialize_end();
        
        ret = (int) rc;
        if (ret != EOK)
                return (ssize_t) ret;
        
        return (ssize_t) IPC_GET_ARG1(answer);
}

/** Read from device using its character interface.
 *
 * @param dev_phone Phone to the device.
 * @param buf       Output buffer for the data
 *                  read from the device.
 * @param len       Maximum length 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 read_dev(int dev_phone, void *buf, size_t len)
{
        return rw_dev(dev_phone, buf, len, true);
}

/** Write to device using its character interface.
 *
 * @param dev_phone Phone to the device.
 * @param buf       Input buffer containg the data
 *                  to be written to the device.
 * @param len       Maximum length 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 write_dev(int dev_phone, void *buf, size_t len)
{
        return rw_dev(dev_phone, buf, len, false);
}

/** @}
 */