Add a switch to allow operation on unsupported hubs

Show power switching type supported by a hub:

* ppps   - per-port power switching
* ganged - ganged power switching
* nops   - no power switching

Add --force (-f) switch to allow operation on non-ppps hubs.
Use `-f` at your own risk, this most likely will not work to actually switch power.

For ganged hubs, you may need to turn power off for all hub ports to get any effect.
For nops hubs, it is not likely to work at all, but might be useful for informational purposes.

Also, instead of printing recipe on how to fix USB permissions on Linux,
forward user to web page with detailed explanations.

Closes #260, #280.

Author: mvp

uhubctl.c

@@ -190,7 +190,7 @@ struct hub_info {
     int bcd_usb;
     int super_speed; /* 1 if super speed hub, and 0 otherwise */
     int nports;
-    int ppps;
+    int lpsm; /* logical power switching mode */
     int actionable; /* true if this hub is subject to action */
     char container_id[33]; /* container ID as hex string */
     char vendor[16];
@@ -218,6 +218,7 @@ static int opt_repeat = 1;
 static int opt_wait   = 20; /* wait before repeating in ms */
 static int opt_exact  = 0;  /* exact location match - disable USB3 duality handling */
 static int opt_reset  = 0;  /* reset hub after operation(s) */
+static int opt_force  = 0;  /* force operation even on unsupported hubs */
 
 static const struct option long_options[] = {
     { "location", required_argument, NULL, 'l' },
@@ -229,6 +230,7 @@ static const struct option long_options[] = {
     { "repeat",   required_argument, NULL, 'r' },
     { "wait",     required_argument, NULL, 'w' },
     { "exact",    no_argument,       NULL, 'e' },
+    { "force",    no_argument,       NULL, 'f' },
     { "reset",    no_argument,       NULL, 'R' },
     { "version",  no_argument,       NULL, 'v' },
     { "help",     no_argument,       NULL, 'h' },
@@ -252,6 +254,7 @@ static int print_usage()
         "--delay,    -d - delay for cycle action [%g sec].\n"
         "--repeat,   -r - repeat power off count [%d] (some devices need it to turn off).\n"
         "--exact,    -e - exact location (no USB3 duality handling).\n"
+        "--force,    -f - force operation even on unsupported hubs.\n"
         "--reset,    -R - reset hub after each power-on action, causing all devices to reassociate.\n"
         "--wait,     -w - wait before repeat power off [%d ms].\n"
         "--version,  -v - print program version.\n"
@@ -447,7 +450,6 @@ static int get_hub_info(struct libusb_device *dev, struct hub_info *info)
                 }
             }
 
-            info->ppps = 0;
             /* Logical Power Switching Mode */
             int lpsm = uhd->wHubCharacteristics[0] & HUB_CHAR_LPSM;
             if (lpsm == HUB_CHAR_COMMON_LPSM && info->nports == 1) {
@@ -458,15 +460,8 @@ static int get_hub_info(struct libusb_device *dev, struct hub_info *info)
             if (lpsm == HUB_CHAR_COMMON_LPSM && strcasecmp(info->vendor, "2109:3431")==0) {
                 lpsm = HUB_CHAR_INDV_PORT_LPSM;
             }
-            /* Over-Current Protection Mode */
-            int ocpm = uhd->wHubCharacteristics[0] & HUB_CHAR_OCPM;
-            /* LPSM must be supported per-port, and OCPM per port or ganged */
-            if ((lpsm == HUB_CHAR_INDV_PORT_LPSM) &&
-                (ocpm == HUB_CHAR_INDV_PORT_OCPM ||
-                 ocpm == HUB_CHAR_COMMON_OCPM))
-            {
-                info->ppps = 1;
-            }
+            info->lpsm = lpsm;
+            rc = 0;
         } else {
             rc = len;
         }
@@ -524,7 +519,7 @@ static int get_device_description(struct libusb_device * dev, struct descriptor_
     int rc;
     int id_vendor  = 0;
     int id_product = 0;
-    char ports[64]   = "";
+    char hub_specific[64] = "";
     struct libusb_device_descriptor desc;
     struct libusb_device_handle *devh = NULL;
     rc = libusb_get_device_descriptor(dev, &desc);
@@ -554,8 +549,16 @@ static int get_device_description(struct libusb_device * dev, struct descriptor_
             struct hub_info info;
             rc = get_hub_info(dev, &info);
             if (rc == 0) {
-                snprintf(ports, sizeof(ports), ", USB %x.%02x, %d ports",
-                   info.bcd_usb >> 8, info.bcd_usb & 0xFF, info.nports);
+                const char * lpsm_type;
+                if (info.lpsm == HUB_CHAR_INDV_PORT_LPSM) {
+                    lpsm_type = "ppps";
+                } else if (info.lpsm == HUB_CHAR_COMMON_LPSM) {
+                    lpsm_type = "ganged";
+                } else {
+                    lpsm_type = "nops";
+                }
+                snprintf(hub_specific, sizeof(hub_specific), ", USB %x.%02x, %d ports, %s",
+                   info.bcd_usb >> 8, info.bcd_usb & 0xFF, info.nports, lpsm_type);
             }
         }
         libusb_close(devh);
@@ -566,7 +569,7 @@ static int get_device_description(struct libusb_device * dev, struct descriptor_
         ds->vendor[0]  ? " " : "", ds->vendor,
         ds->product[0] ? " " : "", ds->product,
         ds->serial[0]  ? " " : "", ds->serial,
-        ports
+        hub_specific
     );
     return 0;
 }
@@ -700,9 +703,10 @@ static int usb_find_hubs()
         rc = get_hub_info(dev, &info);
         if (rc) {
             perm_ok = 0; /* USB permission issue? */
+            continue;
         }
         get_device_description(dev, &info.ds);
-        if (info.ppps) { /* PPPS is supported */
+        if (info.lpsm == HUB_CHAR_INDV_PORT_LPSM || opt_force) {
             if (hub_count < MAX_HUBS) {
                 info.actionable = 1;
                 if (strlen(opt_location) > 0) {
@@ -836,6 +840,14 @@ static int usb_find_hubs()
             hub_phys_count++;
         }
     }
+#ifdef __gnu_linux__
+    if (perm_ok == 0 && geteuid() != 0) {
+        fprintf(stderr,
+            "There were permission problems while accessing USB.\n"
+            "Follow https://git.io/JIB2Z for a fix!\n"
+        );
+    }
+#endif
     if (perm_ok == 0 && hub_phys_count == 0) {
         return LIBUSB_ERROR_ACCESS;
     }
@@ -850,7 +862,7 @@ int main(int argc, char *argv[])
     int option_index = 0;
 
     for (;;) {
-        c = getopt_long(argc, argv, "l:L:n:a:p:d:r:w:hveR",
+        c = getopt_long(argc, argv, "l:L:n:a:p:d:r:w:hvefR",
             long_options, &option_index);
         if (c == -1)
             break;  /* no more options left */
@@ -898,6 +910,9 @@ int main(int argc, char *argv[])
         case 'r':
             opt_repeat = atoi(optarg);
             break;
+        case 'f':
+            opt_force = 1;
+            break;
         case 'e':
             opt_exact = 1;
             break;
@@ -956,18 +971,6 @@ int main(int argc, char *argv[])
             strlen(opt_location) ? " at location " : "",
             opt_location
         );
-#ifdef __gnu_linux__
-        if (rc < 0 && geteuid() != 0) {
-            fprintf(stderr,
-                "There were permission problems while accessing USB.\n"
-                "To fix this, run this tool as root using 'sudo uhubctl',\n"
-                "or add one or more udev rules like below\n"
-                "to file '/etc/udev/rules.d/52-usb.rules':\n"
-                "SUBSYSTEM==\"usb\", ATTR{idVendor}==\"2001\", MODE=\"0666\"\n"
-                "then run 'sudo udevadm trigger --attr-match=subsystem=usb'\n"
-            );
-        }
-#endif
         rc = 1;
         goto cleanup;
     }