X-Git-Url: http://dolda2000.com/gitweb/?p=utils.git;a=blobdiff_plain;f=gpio.c;h=5c1d7187a818a856c63d4cb373c98870cdf9fc90;hp=1d8b322869e3b15f691cdd9a6ccd856aaad30887;hb=f7bd9b51138dbccb7cc2fd27f07ef66d5d2d79cf;hpb=cc450aa9fb0792ca0c5ae05f648e04dba0fc19d1

diff --git a/gpio.c b/gpio.c
index 1d8b322..5c1d718 100644
--- a/gpio.c
+++ b/gpio.c
@@ -17,6 +17,7 @@ static const int imap[] = {
 };
 static const int *umap = bmap;
 static int mapn = sizeof(bmap) / sizeof(*bmap);
+static int preserve = 0;
 
 static int mappin(int num)
 {
@@ -25,29 +26,67 @@ static int mappin(int num)
     return(umap[num]);
 }
 
-static void setport(int p, int v)
+static void export(int p)
+{
+    char path[256];
+    FILE *fp;
+    int rp;
+    
+    if((rp = mappin(p)) < 0)
+	errx(1, "%i: no such port", p);
+    sprintf(path, "/sys/class/gpio/gpio%i", rp);
+    if(!access(path, R_OK | X_OK))
+	return;
+    if(preserve)
+	errx(2, "gpio%i: not exported", rp);
+    sprintf(path, "/sys/class/gpio/export");
+    if((fp = fopen(path, "w")) == NULL)
+	err(1, "%s", path);
+    fprintf(fp, "%i\n", rp); fflush(fp);
+    if(ferror(fp))
+	errx(1, "gpio%i: could not export", rp);
+    fclose(fp);
+    sprintf(path, "/sys/class/gpio/gpio%i", rp);
+    if(access(path, R_OK | X_OK))
+	errx(1, "gpio%i: still not available after export", rp);
+}
+
+static void checkdir(int rp, char *dir)
 {
     char path[256], line[256];
     FILE *fp;
-    int rv, rp;
+    int rv;
+    size_t ln;
     
-    if((rp = mappin(p)) < 0) {
-	fprintf(stderr, "gpio: %i: no such port\n", p);
-	exit(1);
-    }
     sprintf(path, "/sys/class/gpio/gpio%i/direction", rp);
     if((fp = fopen(path, "r")) == NULL)
 	err(1, "%s", path);
     rv = !!fgets(line, sizeof(line), fp);
     fclose(fp);
-    if(!rv || strcmp(line, "out\n")) {
+    if(!rv || ((ln = strlen(line)) < 1) || (line[ln - 1] != '\n'))
+	errx(1, "gpio%i: could not read direction", rp);
+    line[ln - 1] = 0;
+    if(strcmp(line, dir)) {
+	if(preserve)
+	    errx(2, "gpio%i: direction not set to %s", rp, dir);
 	if((fp = fopen(path, "w")) == NULL)
 	    err(1, "%s", path);
-	fprintf(fp, "out\n"); fflush(fp);
+	fprintf(fp, "%s\n", dir); fflush(fp);
 	if(ferror(fp))
-	    errx(1, "gpio%i: could not set to output", rp);
+	    errx(1, "gpio%i: could not set to direction to %s", rp, dir);
 	fclose(fp);
     }
+}
+
+static void setport(int p, int v)
+{
+    char path[256];
+    FILE *fp;
+    int rp;
+    
+    if((rp = mappin(p)) < 0)
+	errx(1, "%i: no such port", p);
+    checkdir(rp, "out");
     sprintf(path, "/sys/class/gpio/gpio%i/value", rp);
     if((fp = fopen(path, "w")) == NULL)
 	err(1, "%s", path);
@@ -57,17 +96,41 @@ static void setport(int p, int v)
     fclose(fp);
 }
 
+static int getport(int p)
+{
+    char path[256], line[256], *ep;
+    FILE *fp;
+    int rv, rp;
+    size_t ln;
+    
+    if((rp = mappin(p)) < 0)
+	errx(1, "%i: no such port", p);
+    checkdir(rp, "in");
+    sprintf(path, "/sys/class/gpio/gpio%i/value", rp);
+    if((fp = fopen(path, "r")) == NULL)
+	err(1, "%s", path);
+    rv = !!fgets(line, sizeof(line), fp);
+    fclose(fp);
+    if(!rv || ((ln = strlen(line)) < 1) || (line[ln - 1] != '\n'))
+	errx(1, "gpio%i: could not read direction", rp);
+    line[ln - 1] = 0;
+    rv = (int)strtol(line, &ep, 10);
+    if(*ep)
+	errx(1, "gpio%i: unexpected contents: %s", rp, line);
+    return(rv);
+}
+
 static void usage(FILE *out)
 {
-    fprintf(out, "usage: gpio [-hi] PORT=VAL...\n");
+    fprintf(out, "usage: gpio [-hip] {PORT=VAL|PORT==VAL|PORT?}...\n");
 }
 
 int main(int argc, char **argv)
 {
     int c, i, port, val;
-    char *p, *e;
+    char *e;
     
-    while((c = getopt(argc, argv, "hi")) >= 0) {
+    while((c = getopt(argc, argv, "hip")) >= 0) {
 	switch(c) {
 	case 'h':
 	    usage(stdout);
@@ -76,6 +139,9 @@ int main(int argc, char **argv)
 	    umap = imap;
 	    mapn = sizeof(imap) / sizeof(*imap);
 	    break;
+	case 'p':
+	    preserve = 1;
+	    break;
 	default:
 	    usage(stderr);
 	    return(1);
@@ -86,27 +152,31 @@ int main(int argc, char **argv)
 	return(1);
     }
     for(i = optind; i < argc; i++) {
-	if((p = strchr(argv[i], '=')) == NULL) {
-	    fprintf(stderr, "gpio: %s: not of the form PORT=VAL\n", argv[i]);
-	    exit(1);
-	}
 	port = strtol(argv[i], &e, 10);
-	if(e != p) {
-	    fprintf(stderr, "gpio: %s: not of the form PORT=VAL\n", argv[i]);
-	    exit(1);
-	}
-	val = strtol(p + 1, &e, 10);
-	if(*e) {
-	    fprintf(stderr, "gpio: %s: not of the form PORT=VAL\n", argv[i]);
-	    exit(1);
+	if((e > argv[i]) && (e[0] == '=') && (e[1] == '=')) {
+	    val = strtol(e + 2, &e, 10);
+	    if(*e)
+		errx(1, "gpio: %s: not of the form PORT==VAL", argv[i]);
+	    export(port);
+	    return(getport(port) != val);
+	} else if((e > argv[i]) && (e[0] == '=')) {
+	    val = strtol(e + 1, &e, 10);
+	    if(*e)
+		errx(1, "gpio: %s: not of the form PORT=VAL", argv[i]);
+	    export(port);
+	    setport(port, val);
+	} else if((e > argv[i]) && (e[0] == '?') && !e[1]) {
+	    export(port);
+	    printf("%i\n", getport(port));
+	} else {
+	    errx(1, "gpio: %s: not a valid argument", argv[i]);
 	}
-	setport(port, val);
     }
     return(0);
 }
 
 /*
  * Local Variables:
- * compile-command: "gcc -Wall -g -O2 -march=native -o gpio gpio.c"
+ * compile-command: "gcc -Wall -g -O2 -march=native -c -o gpio.o gpio.c && gcc -o gpio gpio.o"
  * End:
  */