Resolve porting mistake on initial bus registration

On first registering a new bus in the the NetBSD build of the code usb_kthread_create(usb_create_event_thread, sc) is called which in turn creates the main event thread ("usb_event_thread").
The first thing usb_event_thread() does is set
  sc->sc_bus->needs_explore = 1;
  usb_discover(sc);
however in the RISC OS version of the code (usb.c around line 254) only the first action is performed, no discover happens.
This change schedules a callback via usb_needs_explore_callback() which in turn calls discover_callback() when the OS is next free, which calls usb_discover() for each bus in an equivalent way to NetBSD's event thread. There's then no longer any need for the special one-shot 11s rediscover callback, only the repeating 30s rediscover is needed.

For reference, the places that set needs_explore in this version are all in usb.c
  Line 254: set, but doesn't schedule a callback, as noted above
  Line 339: code not compiled for __riscos
  Line 548: set, does schedule a callback
  Line 727: cleared, in usb_discover()
  Line 743: set, does schedule a callback
  Line 756: code not called in RISC OS

NetBSD uses 500ms initial delay before discover, then 60s between discovers (or until requested by a hub, whichever is sooner).
RISC OS has a periodic callback of 30s (in usbmodule.c) and an initial discover of however long it is from the bus being registered until callbacks next fire usb_event_thread(), assumed ~500ms.

Version 1.07. Tagged as 'NetBSD-1_07'

VersionNum

-/* (1.06)
+/* (1.07)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        1.06
+#define Module_MajorVersion_CMHG        1.07
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                09 Nov 2015
+#define Module_Date_CMHG                12 Nov 2015
 
-#define Module_MajorVersion             "1.06"
-#define Module_Version                  106
+#define Module_MajorVersion             "1.07"
+#define Module_Version                  107
 #define Module_MinorVersion             ""
-#define Module_Date                     "09 Nov 2015"
+#define Module_Date                     "12 Nov 2015"
 
-#define Module_ApplicationDate          "09-Nov-15"
+#define Module_ApplicationDate          "12-Nov-15"
 
 #define Module_ComponentName            "NetBSD"
 #define Module_ComponentPath            "mixed/RiscOS/Sources/HWSupport/USB/NetBSD"
 
-#define Module_FullVersion              "1.06"
-#define Module_HelpVersion              "1.06 (09 Nov 2015)"
-#define Module_LibraryVersionInfo       "1:6"
+#define Module_FullVersion              "1.07"
+#define Module_HelpVersion              "1.07 (12 Nov 2015)"
+#define Module_LibraryVersionInfo       "1:7"

build/Version

@@ -8,5 +8,5 @@
 #define EHCIDriverModule_Module_Date_CMHG  04 Nov 2015
 #define EHCIDriverModule_MajorVersion_CMHG 0.29
         
-#define USBDriverModule_Module_Date_CMHG   28 Sep 2015
-#define USBDriverModule_MajorVersion_CMHG  0.78
+#define USBDriverModule_Module_Date_CMHG   12 Nov 2015
+#define USBDriverModule_MajorVersion_CMHG  0.79

build/c/usbmodule

@@ -289,10 +289,6 @@ static _kernel_oserror *init_handler(_kernel_swi_regs *r, void *pw, void* h)
     _swix (OS_ServiceCall, _INR (0, 1),
         Service_USB_USBDriverStarting,
         Service_USB);
-    /* set up a periodic call to re-discover anything lurking */
-    callx_add_callevery(3000,re_discover,NULL);
-    /* set up a one off call to re-discover anything lurking early */
-    callx_add_callafter(1200,re_discover,NULL);
     return NULL;
 }
 
@@ -337,6 +333,9 @@ _kernel_oserror *module_init(const char *cmd_tail, int podule_base, void *pw)
     /* do this in a callback so that clients can call our SWIs */
     callx_add_callback (init_handler, 0);
 
+    /* set up a periodic call to re-discover anything lurking */
+    callx_add_callevery(3000,re_discover,NULL);
+
     _swix (OS_Claim, _INR(0,2), PointerV, pointerv_entry, pw);
 
     return 0;
@@ -1128,12 +1127,12 @@ struct device* get_usbdev (int unit)
 }
 
 /*---------------------------------------------------------------------------*/
-static int rd_active = 0;
 static _kernel_oserror *re_discover(_kernel_swi_regs *r, void *pw, void* h)
 {
-//    struct device* dev;
-    if(rd_active) return NULL;
-    rd_active++;
+    static bool rd_active = false;
+
+    if (rd_active) return NULL;
+    rd_active = true;
     for (int i = 1; i < usbbus_no; i++)
     {
         if (get_softc (i << 16) != NULL)
@@ -1142,7 +1141,7 @@ static _kernel_oserror *re_discover(_kernel_swi_regs *r, void *pw, void* h)
             usbioctl (i << 16, USB_DISCOVER, 0, 0, 0);
         }
     }
-    rd_active=0;
+    rd_active = false;
     return NULL;
 }
 

dev/usb/c/usb

@@ -249,8 +249,9 @@ USB_ATTACH(usb)
 
 	config_pending_incr();
 #ifdef __riscos
-        /* set the explore flag here since threads don't do anything */
+	/* set the explore flag here since threads don't do anything */
 	sc->sc_bus->needs_explore = 1;
+	usb_needs_explore_callback(sc->sc_bus);
 #else
 	usb_kthread_create(usb_create_event_thread, sc);
 #endif
@@ -543,11 +544,10 @@ usbioctl(dev_t devt, u_long cmd, caddr_t data, int flag, usb_proc_ptr p)
 		break;
 #endif /* USB_DEBUG */
 #ifdef __riscos
-        case USB_DISCOVER:
-                sc->sc_bus->needs_explore = 1;
-                usb_needs_explore_callback (sc->sc_bus);
-//                usb_discover(sc);
-                break;
+	case USB_DISCOVER:
+		sc->sc_bus->needs_explore = 1;
+		usb_needs_explore_callback(sc->sc_bus);
+		break;
 #endif
 	case USB_REQUEST:
 	{
@@ -567,7 +567,7 @@ usbioctl(dev_t devt, u_long cmd, caddr_t data, int flag, usb_proc_ptr p)
 		if (len < 0 || len > 32768)
 			return (EINVAL);
 		if (addr < 0 || addr >= USB_MAX_DEVICES ||
-		    sc->sc_bus->devices[addr] == 0)
+		    sc->sc_bus->devices[addr] == NULL)
 			return (EINVAL);
 		if (len != 0) {
 			iov.iov_base = (caddr_t)ur->ucr_data;