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132 lines
3.4 KiB
C
132 lines
3.4 KiB
C
/**
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* Character device messaging loop.
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*
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* Copyright (C) 2013, INRIA.
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*
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* @ingroup chardev
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* @{
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* @file
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* @brief Runs an infinite loop in a separate thread to handle access to character devices such as uart.
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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* @}
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*/
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#include <stdio.h>
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#include <errno.h>
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#include "irq.h"
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#include "msg.h"
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#include "ringbuffer.h"
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#include "posix_io.h"
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/* increase stack size in uart0 when setting this to 1 */
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#define ENABLE_DEBUG (0)
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#include "debug.h"
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static int min(int a, int b)
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{
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if (b > a) {
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return a;
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}
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else {
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return b;
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}
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}
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void chardev_loop(ringbuffer_t *rb)
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{
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msg_t m;
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kernel_pid_t reader_pid = KERNEL_PID_UNDEF;
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struct posix_iop_t *r = NULL;
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puts("UART0 thread started.");
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while (1) {
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msg_receive(&m);
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if (!msg_sent_by_int(&m)) {
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DEBUG("Receiving message from another thread: ");
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switch(m.type) {
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case OPEN:
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DEBUG("OPEN\n");
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if (reader_pid == KERNEL_PID_UNDEF) {
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reader_pid = m.sender_pid;
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/* no error */
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m.content.value = 0;
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}
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else {
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m.content.value = -EBUSY;
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}
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msg_reply(&m, &m);
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break;
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case READ:
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DEBUG("READ\n");
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if (m.sender_pid != reader_pid) {
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m.content.value = -EINVAL;
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r = NULL;
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msg_reply(&m, &m);
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}
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else {
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r = (struct posix_iop_t *)(void*)m.content.ptr;
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}
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break;
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case CLOSE:
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DEBUG("CLOSE\n");
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if (m.sender_pid == reader_pid) {
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DEBUG("uart0_thread: closing file from %" PRIkernel_pid "\n", reader_pid);
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reader_pid = KERNEL_PID_UNDEF;
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r = NULL;
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m.content.value = 0;
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}
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else {
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m.content.value = -EINVAL;
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}
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msg_reply(&m, &m);
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break;
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default:
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DEBUG("UNKNOWN\n");
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m.content.value = -EINVAL;
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msg_reply(&m, &m);
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}
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}
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if (rb->avail && (r != NULL)) {
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DEBUG("Data is available\n");
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unsigned state = disableIRQ();
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int nbytes = min(r->nbytes, rb->avail);
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DEBUG("uart0_thread [%i]: sending %i bytes received from %" PRIkernel_pid " to pid %" PRIkernel_pid "\n", thread_getpid(), nbytes, m.sender_pid, reader_pid);
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ringbuffer_get(rb, r->buffer, nbytes);
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r->nbytes = nbytes;
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m.sender_pid = reader_pid;
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m.type = OPEN;
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m.content.ptr = (char *)r;
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msg_reply(&m, &m);
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r = NULL;
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restoreIRQ(state);
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}
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}
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}
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void *chardev_thread_entry(void *rb_)
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{
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ringbuffer_t *rb = rb_;
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chardev_loop(rb);
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return NULL;
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}
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