Remove IRQ-level malloc from USB setup

Fixes a hang found while debugging #614.  Do all memory allocations and
USB descriptor setup in main code prior to `tusb_init()`.  Avoids potential
deadlock in cases where the app is allocating while the USB port is being
set up.

cores/rp2040/RP2040USB.cpp

@@ -120,49 +120,49 @@ int __USBGetMouseReportID() {
     return __USBInstallKeyboard ? 2 : 1;
 }
 
-static uint8_t *GetDescHIDReport(int *len) {
-    static uint8_t *report = nullptr;
-    int report_len = 0;
+static int      __hid_report_len = 0;
+static uint8_t *__hid_report     = nullptr;
 
-    if (report) {
-        free(report);
-        report = nullptr;
+static uint8_t *GetDescHIDReport(int *len) {
+    if (len) {
+        *len = __hid_report_len;
     }
+    return __hid_report;
+}
 
+static void __SetupDescHIDReport() {
     if (__USBInstallKeyboard && __USBInstallMouse) {
         uint8_t desc_hid_report[] = {
             TUD_HID_REPORT_DESC_KEYBOARD(HID_REPORT_ID(1)),
             TUD_HID_REPORT_DESC_MOUSE(HID_REPORT_ID(2))
         };
-        report_len = sizeof(desc_hid_report);
-        report = (uint8_t *)malloc(report_len);
-        if (report) {
-            memcpy(report, desc_hid_report, report_len);
+        __hid_report = (uint8_t *)malloc(sizeof(desc_hid_report));
+        if (__hid_report) {
+            __hid_report_len = sizeof(desc_hid_report);
+            memcpy(__hid_report, desc_hid_report, __hid_report_len);
         }
     } else if (__USBInstallKeyboard && ! __USBInstallMouse) {
         uint8_t desc_hid_report[] = {
             TUD_HID_REPORT_DESC_KEYBOARD(HID_REPORT_ID(1))
         };
-        report_len = sizeof(desc_hid_report);
-        report = (uint8_t *)malloc(report_len);
-        if (report) {
-            memcpy(report, desc_hid_report, report_len);
+        __hid_report = (uint8_t *)malloc(sizeof(desc_hid_report));
+        if (__hid_report) {
+            __hid_report_len = sizeof(desc_hid_report);
+            memcpy(__hid_report, desc_hid_report, __hid_report_len);
         }
-    } else { // if (!__USBInstallKeyboard && __USBInstallMouse) {
+    } else if (! __USBInstallKeyboard &&  __USBInstallMouse) {
         uint8_t desc_hid_report[] = {
             TUD_HID_REPORT_DESC_MOUSE(HID_REPORT_ID(1))
         };
-        report_len = sizeof(desc_hid_report);
-        report = (uint8_t *)malloc(report_len);
-        if (report) {
-            memcpy(report, desc_hid_report, report_len);
+        __hid_report = (uint8_t *)malloc(sizeof(desc_hid_report));
+        if (__hid_report) {
+            __hid_report_len = sizeof(desc_hid_report);
+            memcpy(__hid_report, desc_hid_report, __hid_report_len);
         }
+    } else {
+        __hid_report = nullptr;
+        __hid_report_len = 0;
     }
-
-    if (len) {
-        *len = report_len;
-    }
-    return report;
 }
 
 // Invoked when received GET HID REPORT DESCRIPTOR
@@ -173,11 +173,13 @@ uint8_t const * tud_hid_descriptor_report_cb(uint8_t instance) {
     return GetDescHIDReport(nullptr);
 }
 
-
+static uint8_t *usbd_desc_cfg = nullptr;
 const uint8_t *tud_descriptor_configuration_cb(uint8_t index) {
     (void)index;
-    static uint8_t *usbd_desc_cfg = nullptr;
+    return usbd_desc_cfg;
+}
 
+static void __SetupUSBDescriptor() {
     if (!usbd_desc_cfg) {
         bool hasHID = __USBInstallKeyboard || __USBInstallMouse;
 
@@ -229,7 +231,6 @@ const uint8_t *tud_descriptor_configuration_cb(uint8_t index) {
             }
         }
     }
-    return usbd_desc_cfg;
 }
 
 const uint16_t *tud_descriptor_string_cb(uint8_t index, uint16_t langid) {
@@ -295,6 +296,9 @@ void __USBStart() {
         return;
     }
 
+    __SetupDescHIDReport();
+    __SetupUSBDescriptor();
+
     mutex_init(&__usb_mutex);
 
     tusb_init();