mirror of
git://projects.qi-hardware.com/wernermisc.git
synced 2024-12-28 21:52:25 +02:00
194 lines
3.5 KiB
C
194 lines
3.5 KiB
C
/*
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* libbb/libbbd.c - Bitbang library daemon
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*
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* Written 2010-2011 by Werner Almesberger
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* Copyright 2010-2011 Werner Almesberger
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <poll.h>
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#include <errno.h>
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#include <syslog.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include "libbb.h"
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#define FD_DIR "/proc/self/fd"
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#define DRIVER_NAME "jz4740-mmc.0"
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#define UNBIND_PATH "/sys/bus/platform/drivers/jz4740-mmc/unbind"
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#define BIND_PATH "/sys/bus/platform/drivers/jz4740-mmc/bind"
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static void closefds(void)
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{
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DIR *dir;
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const struct dirent *de;
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int fd;
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dir = opendir(FD_DIR);
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if (!dir) {
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perror(FD_DIR);
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exit(1);
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}
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while ((de = readdir(dir))) {
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if (*de->d_name == '.')
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continue;
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fd = atoi(de->d_name);
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if (fd == 1 || fd == 2)
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continue;
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if (fd == dirfd(dir))
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continue;
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(void) close(fd);
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}
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closedir(dir);
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}
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static int echo(const char *msg, const char *path)
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{
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int fd;
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ssize_t wrote;
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int len = strlen(msg);
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fd = open(path, O_WRONLY);
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if (fd < 0) {
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perror(path);
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return -errno;
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}
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wrote = write(fd, msg, len);
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if (wrote < 0) {
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perror(path);
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return -errno;
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}
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if (wrote != len) {
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fprintf(stderr, "short write: %d < %d\n", (int) wrote, len);
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return -ENOSPC;
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}
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if (close(fd) < 0) {
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perror(path);
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return -errno;
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}
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return 0;
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}
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static void lock_area(int fd, off_t from, off_t len)
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{
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if (lseek(fd, from, SEEK_SET) == (off_t) -1) {
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perror("lseek");
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exit(1);
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}
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if (lockf(fd, F_LOCK, len) < 0) {
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perror("lockf");
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exit(1);
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}
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}
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static int send_fd(int s, int fd)
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{
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struct msghdr msg;
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struct cmsg {
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struct cmsghdr hdr;
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int fd;
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} cmsg;
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memset(&msg, 0, sizeof(msg));
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msg.msg_control = &cmsg;
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msg.msg_controllen = sizeof(cmsg);
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cmsg.hdr.cmsg_level = SOL_SOCKET;
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cmsg.hdr.cmsg_type = SCM_RIGHTS;
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cmsg.hdr.cmsg_len = sizeof(cmsg);
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cmsg.fd = fd;
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if (sendmsg(s, &msg, 0) >= 0)
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return 0;
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perror("sendmsg");
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return -1;
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}
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static int wait_for_close(int s)
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{
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struct pollfd fds[1];
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int res;
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fds->fd = s;
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fds->events = 0;
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fds->revents = POLLHUP;
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res = poll(fds, 1, -1);
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if (res < 0) {
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perror("poll");
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return -1;
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}
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if (!res) {
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fprintf(stderr, "poll inexplicably returned 0\n");
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return -1;
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}
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return 0;
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}
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int main(int argc, char **argv)
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{
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int fd, res;
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int exit_code = 1;
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fprintf(stderr, "setsid\n");
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if (setsid() == (pid_t) -1) {
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perror("setsid");
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exit(1);
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}
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fprintf(stderr, "closefds\n");
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closefds();
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fprintf(stderr, "open devmem\n");
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fd = open("/dev/mem", O_RDWR | O_SYNC);
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if (fd < 0) {
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perror("/dev/mem");
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exit(1);
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}
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fprintf(stderr, "lock_area\n");
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lock_area(fd, LIBBB_GPIO_BASE+LIBBB_PORT_D_OFFSET,
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LIBBB_PORT_D_WINDOW);
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fprintf(stderr, "echo (unbind)\n");
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if (echo(DRIVER_NAME "\n", UNBIND_PATH) < 0)
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exit(1);
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fprintf(stderr, "send_fd\n");
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if (send_fd(1, fd) < 0)
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goto cleanup;
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fprintf(stderr, "wait_for_close\n");
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if (wait_for_close(1) < 0)
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goto cleanup;
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exit_code = 0;
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cleanup:
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fprintf(stderr, "echo (bind)n");
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res = echo(DRIVER_NAME "\n", BIND_PATH);
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if (res < 0) {
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/* stderr may no longer exist. report to syslog. */
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openlog("libbbd", LOG_CONS, LOG_USER);
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syslog(LOG_CRIT, "libbd failed to re-bind driver (%d)", res);
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}
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fprintf(stderr, "exit\n");
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return exit_code;
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}
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