gpio: Auto-export ports.

[utils.git] / gpio.c

diff --git a/gpio.c b/gpio.c
index babc061..0179c18 100644 (file)
--- a/gpio.c
+++ b/gpio.c
@@ -6,40 +6,115 @@
 #include <errno.h>
 #include <err.h>
 
+static const int bmap[] = {
+    -1,
+    -1, -1,  2, -1,  3, -1,  4, 14, -1, 15, 17, 18, 27, -1, 22, 23, -1, 24, 10, -1,
+     9, 25, 11,  8, -1,  7, -1, -1,  5, -1,  6, 12, 13, -1, 19, 16, 21, 20, -1, 21,
+};
+static const int imap[] = {
+    -1, -1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13,
+    14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, 27,
+};
+static const int *umap = bmap;
+static int mapn = sizeof(bmap) / sizeof(*bmap);
+static int preserve = 0;
+
+static int mappin(int num)
+{
+    if((num < 0) || (num >= mapn))
+       return(-1);
+    return(umap[num]);
+}
+
+static void export(int p)
+{
+    char path[256];
+    FILE *fp;
+    int rp;
+    
+    if((rp = mappin(p)) < 0)
+       errx(1, "%i: no such port\n", 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 setport(int p, int v)
 {
     char path[256], line[256];
     FILE *fp;
-    int rv;
+    int rv, rp;
     
-    sprintf(path, "/sys/class/gpio/gpio%i/direction", p);
+    if((rp = mappin(p)) < 0)
+       errx(1, "%i: no such port\n", p);
+    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(preserve)
+           errx(2, "gpio%i: not set to output", rp);
        if((fp = fopen(path, "w")) == NULL)
            err(1, "%s", path);
        fprintf(fp, "out\n"); fflush(fp);
        if(ferror(fp))
-           errx(1, "gpio%i: could not set to output", p);
+           errx(1, "gpio%i: could not set to output", rp);
        fclose(fp);
     }
-    sprintf(path, "/sys/class/gpio/gpio%i/value", p);
+    sprintf(path, "/sys/class/gpio/gpio%i/value", rp);
     if((fp = fopen(path, "w")) == NULL)
        err(1, "%s", path);
     fprintf(fp, "%i\n", v); fflush(fp);
     if(ferror(fp))
-       errx(1, "gpio%i: could not set value", p);
+       errx(1, "gpio%i: could not set value", rp);
     fclose(fp);
 }
 
+static void usage(FILE *out)
+{
+    fprintf(out, "usage: gpio [-hip] PORT=VAL...\n");
+}
+
 int main(int argc, char **argv)
 {
-    int i, port, val;
+    int c, i, port, val;
     char *p, *e;
     
-    for(i = 1; i < argc; i++) {
+    while((c = getopt(argc, argv, "hip")) >= 0) {
+       switch(c) {
+       case 'h':
+           usage(stdout);
+           return(0);
+       case 'i':
+           umap = imap;
+           mapn = sizeof(imap) / sizeof(*imap);
+           break;
+       case 'p':
+           preserve = 1;
+           break;
+       default:
+           usage(stderr);
+           return(1);
+       }
+    }
+    if(optind >= argc) {
+       usage(stderr);
+       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);
@@ -54,7 +129,14 @@ int main(int argc, char **argv)
            fprintf(stderr, "gpio: %s: not of the form PORT=VAL\n", argv[i]);
            exit(1);
        }
+       export(port);
        setport(port, val);
     }
     return(0);
 }
+
+/*
+ * Local Variables:
+ * compile-command: "gcc -Wall -g -O2 -march=native -o gpio gpio.c"
+ * End:
+ */