Date:2010-11-28 00:21:33 (3 years 9 months ago)
Author:Werner Almesberger
Commit:458702cf54a94a1127a37519269b92638802bcda
Message:libbb: library for bit-banging the Ben's uSD port (in progress)

This doesn't work with old kernels, but 2.6.36 should be better. Haven't
tried it yet, though.
Files: libbb/Makefile (1 diff)
libbb/libbb.c (1 diff)
libbb/libbbd.c (1 diff)

Change Details

libbb/Makefile
1CC = mipsel-openwrt-linux-uclibc-gcc
2
3PREFIX = /usr/local
4
5LIBBD_PATH = $(PREFIX)/lib/libbbd
6
7CFLAGS = -Wall -DLIBBD_PATH='"$(LIBBD_PATH)"'
8
9MAIN = libbb.a libbbd
10
11.PHONY: all install uninstall clean spotless upload
12
13all: $(MAIN)
14
15libbb.a: libbb.o
16        $(AR) cr $@ $^
17
18libbb.o libbd: libbb.h
19
20install: $(MAIN)
21        install -D libbb.a $(PREFIX)/lib/
22        install -D libbbd $(LIBBD_PATH)
23
24uninstall:
25        rm -f $(PREFIX)/lib/libbb.a
26        rm -f $(LIBBD_PATH)
27
28clean:
29        rm -f libbb.o
30
31spotless: clean
32        rm -f $(MAIN)
33
34upload: libbbd
35        scp libbbd ben:/usr/local/lib/
libbb/libbb.c
1/*
2 * libbb/libbb.c - Bitbang library
3 *
4 * Written 2010 by Werner Almesberger
5 * Copyright 2010 Werner Almesberger
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 */
12
13
14#include <stdlib.h>
15#include <stdio.h>
16#include <unistd.h>
17#include <string.h>
18#include <sys/types.h>
19#include <sys/socket.h>
20//#include <sys/wait.h>
21#include <sys/mman.h>
22
23#include "libbb.h"
24
25
26#define PAGE_SIZE 4096
27
28
29volatile void *libbb_mem;
30
31static int bbd_fd = -1;
32
33
34static int recv_fd(int s)
35{
36    struct msghdr msg;
37    struct cmsg {
38        struct cmsghdr hdr;
39        int fd;
40    } cmsg;
41
42    memset(&msg, 0, sizeof(msg));
43    msg.msg_control = &cmsg;
44    msg.msg_controllen = sizeof(cmsg);
45        if (recvmsg(s, &msg, 0) < 0) {
46        perror("recvmsg");
47        exit(1);
48    }
49    return cmsg.fd;
50}
51
52
53static void child(void)
54{
55    execl(LIBBD_PATH, LIBBD_PATH, NULL);
56    perror(LIBBD_PATH);
57    _exit(1);
58}
59
60
61#if 0
62static int recv_fd(int s)
63{
64    pid_t res;
65
66    res = waitpid(pid, &status, 0);
67    if (res < 0) {
68        perror("waitpid");
69        exit(1);
70    }
71    if (res != pid) {
72        fprintf(stderr, "waitpid returned %d for %d\n",
73            (int) res, (int) pid);
74        exit(1);
75    }
76}
77#endif
78
79
80static int bbd(void)
81{
82    int s[2];
83    pid_t pid;
84
85    if (socketpair(PF_LOCAL, SOCK_DGRAM, 0, s) < 0) {
86        perror("socketpair");
87        exit(1);
88    }
89    if (dup2(s[1], 1) < 0) {
90        perror("dup2");
91        exit(1);
92    }
93
94    pid = fork();
95    if (pid < 0) {
96        perror("fork");
97        exit(1);
98    }
99    if (pid)
100        return recv_fd(s[0]);
101    else
102        child();
103    return -1; /* can't happen */
104}
105
106
107void libbb_open(void)
108{
109    bbd_fd = bbd();
110    libbb_mem = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,
111       bbd_fd, LIBBB_GPIO_BASE);
112    if (libbb_mem == MAP_FAILED) {
113        perror("mmap");
114        exit(1);
115    }
116}
117
118
119
120void libbb_close(void)
121{
122    if (close(bbd_fd) < 0) {
123        perror("close");
124        exit(1);
125    }
126}
libbb/libbbd.c
1/*
2 * libbb/libbbd.c - Bitbang library daemon
3 *
4 * Written 2010 by Werner Almesberger
5 * Copyright 2010 Werner Almesberger
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 */
12
13
14#include <stdlib.h>
15#include <stdio.h>
16#include <unistd.h>
17#include <string.h>
18#include <fcntl.h>
19#include <dirent.h>
20#include <poll.h>
21#include <errno.h>
22#include <syslog.h>
23#include <sys/types.h>
24#include <sys/socket.h>
25
26#include "libbb.h"
27
28
29#define FD_DIR "/proc/self/fd"
30
31#define DRIVER_NAME "jz4740-mmc.0"
32#define UNBIND_PATH "/sys/bus/platform/drivers/jz4740-mmc/unbind"
33#define BIND_PATH "/sys/bus/platform/drivers/jz4740-mmc/bind"
34
35
36static void closefds(void)
37{
38    DIR *dir;
39    const struct dirent *de;
40    int fd;
41
42    dir = opendir(FD_DIR);
43    if (!dir) {
44        perror(FD_DIR);
45        exit(1);
46    }
47    while ((de = readdir(dir))) {
48        if (*de->d_name == '.')
49            continue;
50        fd = atoi(de->d_name);
51        if (fd == 1 || fd == 2)
52            continue;
53        if (fd == dirfd(dir))
54            continue;
55        (void) close(fd);
56    }
57    closedir(dir);
58}
59
60
61static int echo(const char *msg, const char *path)
62{
63    int fd;
64    ssize_t wrote;
65    int len = strlen(msg);
66
67    fd = open(path, O_WRONLY);
68    if (fd < 0) {
69        perror(path);
70        return -errno;
71    }
72    wrote = write(fd, msg, len);
73    if (wrote < 0) {
74        perror(path);
75        return -errno;
76    }
77    if (wrote != len) {
78        fprintf(stderr, "short write: %d < %d\n", (int) wrote, len);
79        return -ENOSPC;
80    }
81    if (close(fd) < 0) {
82        perror(path);
83        return -errno;
84    }
85    return 0;
86}
87
88
89static void lock_area(int fd, off_t from, off_t len)
90{
91    if (lseek(fd, from, SEEK_SET) == (off_t) -1) {
92        perror("lseek");
93        exit(1);
94    }
95    if (lockf(fd, F_LOCK, len) < 0) {
96        perror("lockf");
97        exit(1);
98    }
99}
100
101
102static int send_fd(int s, int fd)
103{
104    struct msghdr msg;
105    struct cmsg {
106        struct cmsghdr hdr;
107        int fd;
108    } cmsg;
109
110    memset(&msg, 0, sizeof(msg));
111    msg.msg_control = &cmsg;
112    msg.msg_controllen = sizeof(cmsg);
113    cmsg.hdr.cmsg_level = SOL_SOCKET;
114    cmsg.hdr.cmsg_type = SCM_RIGHTS;
115    cmsg.hdr.cmsg_len = sizeof(cmsg);
116    cmsg.fd = fd;
117    if (sendmsg(s, &msg, 0) >= 0)
118        return 0;
119    perror("sendmsg");
120    return -1;
121}
122
123
124static int wait_for_close(int s)
125{
126    struct pollfd fds[1];
127    int res;
128
129    fds->fd = s;
130    fds->events = 0;
131    fds->revents = POLLHUP;
132    res = poll(fds, 1, -1);
133    if (res < 0) {
134        perror("poll");
135        return -1;
136    }
137    if (!res) {
138        fprintf(stderr, "poll inexplicably returned 0\n");
139        return -1;
140    }
141    return 0;
142}
143
144
145int main(int argc, char **argv)
146{
147    int fd, res;
148    int exit_code = 1;
149
150fprintf(stderr, "setsid\n");
151    if (setsid() == (pid_t) -1) {
152        perror("setsid");
153        exit(1);
154    }
155fprintf(stderr, "closefds\n");
156    closefds();
157
158fprintf(stderr, "open devmem\n");
159    fd = open("/dev/mem", O_RDWR);
160    if (fd < 0) {
161        perror("/dev/mem");
162        exit(1);
163    }
164fprintf(stderr, "lock_area\n");
165    lock_area(fd, LIBBB_GPIO_BASE+LIBBB_PORT_D_OFFSET,
166        LIBBB_PORT_D_WINDOW);
167
168fprintf(stderr, "echo (unbind)\n");
169    if (echo(DRIVER_NAME "\n", UNBIND_PATH) < 0)
170        exit(1);
171
172fprintf(stderr, "send_fd\n");
173    if (send_fd(1, fd) < 0)
174        goto cleanup;
175
176fprintf(stderr, "wait_for_close\n");
177    if (wait_for_close(1) < 0)
178        goto cleanup;
179
180    exit_code = 0;
181
182cleanup:
183fprintf(stderr, "echo (bind)n");
184    res = echo(DRIVER_NAME "\n", BIND_PATH);
185    if (res < 0) {
186        /* stderr may no longer exist. report to syslog. */
187        openlog("libbbd", LOG_CONS, LOG_USER);
188        syslog(LOG_CRIT, "libbd failed to re-bind driver (%d)", res);
189    }
190
191fprintf(stderr, "exit\n");
192    return exit_code;
193}

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