Make USBHIDKeyboard work at boot

1. Like a real keyboard, the USB interface descriptor will have an interface
   subclass of boot and an interface protocol of keyboard. This will cause
   some PC BIOS to send a SET PROTOCOL BOOT request to the device.

2. When the device sends reports to the host, if the host requested boot
   protocol, don't send a report ID because boot protocol does not use report
   IDs.

3. To work with some simple PC BIOS:
   a. Use endpoint address of 1 for input and output.
   b. Use separate reports for the shift key. These extra reports can be
      disabled by calling USBHIDKeyboard::setShiftKeyReports(false).

Author: RefactorFactory

cores/esp32/esp32-hal-tinyusb.c

@@ -651,7 +651,11 @@ static void usb_device_task(void *param) {
 #endif
 static bool tinyusb_is_initialized = false;
 
-esp_err_t tinyusb_enable_interface(tinyusb_interface_t interface, uint16_t descriptor_len, tinyusb_descriptor_cb_t cb)
+esp_err_t tinyusb_enable_interface(tinyusb_interface_t interface, uint16_t descriptor_len, tinyusb_descriptor_cb_t cb){
+    return tinyusb_enable_interface2(interface, descriptor_len, cb, false);
+}
+
+esp_err_t tinyusb_enable_interface2(tinyusb_interface_t interface, uint16_t descriptor_len, tinyusb_descriptor_cb_t cb, bool reserve_endpoints)
 {
     if(tinyusb_is_initialized){
         log_e("TinyUSB has already started! Interface %s not enabled", (interface >= USB_INTERFACE_MAX)?"":tinyusb_interface_names[interface]);
@@ -661,6 +665,13 @@ esp_err_t tinyusb_enable_interface(tinyusb_interface_t interface, uint16_t descr
         log_e("Interface %s invalid or already enabled", (interface >= USB_INTERFACE_MAX)?"":tinyusb_interface_names[interface]);
         return ESP_FAIL;
     }
+    if(interface == USB_INTERFACE_HID && reserve_endpoints){
+        // Some simple PC BIOS requires specific endpoint addresses for keyboard at boot
+        if(!tinyusb_reserve_out_endpoint(1) ||!tinyusb_reserve_in_endpoint(1)){
+            log_e("HID Reserve Endpoints Failed");
+            return ESP_FAIL;
+        }
+    }
     if(interface == USB_INTERFACE_CDC){
         if(!tinyusb_reserve_out_endpoint(3) ||!tinyusb_reserve_in_endpoint(4) || !tinyusb_reserve_in_endpoint(5)){
             log_e("CDC Reserve Endpoints Failed");

cores/esp32/esp32-hal-tinyusb.h

@@ -94,6 +94,7 @@ typedef enum {
 typedef uint16_t (*tinyusb_descriptor_cb_t)(uint8_t * dst, uint8_t * itf);
 
 esp_err_t tinyusb_enable_interface(tinyusb_interface_t interface, uint16_t descriptor_len, tinyusb_descriptor_cb_t cb);
+esp_err_t tinyusb_enable_interface2(tinyusb_interface_t interface, uint16_t descriptor_len, tinyusb_descriptor_cb_t cb, bool reserve_endpoints);
 uint8_t tinyusb_add_string_descriptor(const char * str);
 uint8_t tinyusb_get_free_duplex_endpoint(void);
 uint8_t tinyusb_get_free_in_endpoint(void);

libraries/USB/src/USBHID.cpp

@@ -39,6 +39,7 @@ static xSemaphoreHandle tinyusb_hid_device_input_sem = NULL;
 static xSemaphoreHandle tinyusb_hid_device_input_mutex = NULL;
 
 static bool tinyusb_hid_is_initialized = false;
+static hid_interface_protocol_enum_t tinyusb_interface_protocol = HID_ITF_PROTOCOL_NONE;
 static uint8_t tinyusb_loaded_hid_devices_num = 0;
 static uint16_t tinyusb_hid_device_descriptor_len = 0;
 static uint8_t * tinyusb_hid_device_descriptor = NULL;
@@ -173,7 +174,7 @@ static bool tinyusb_load_enabled_hid_devices(){
 
     esp_hid_report_map_t *hid_report_map = esp_hid_parse_report_map(tinyusb_hid_device_descriptor, tinyusb_hid_device_descriptor_len);
     if(hid_report_map){
-        log_d("Loaded HID Desriptor with the following reports:");
+        log_d("Loaded HID Descriptor with the following reports:");
         for(uint8_t i=0; i<hid_report_map->reports_len; i++){
             if(hid_report_map->reports[i].protocol_mode == ESP_HID_PROTOCOL_MODE_REPORT){
                 log_d("  ID: %3u, Type: %7s, Size: %2u, Usage: %8s",
@@ -201,14 +202,15 @@ extern "C" uint16_t tusb_hid_load_descriptor(uint8_t * dst, uint8_t * itf)
     tinyusb_hid_is_initialized = true;
 
     uint8_t str_index = tinyusb_add_string_descriptor("TinyUSB HID");
-    uint8_t ep_in = tinyusb_get_free_in_endpoint();
+    // For keyboard boot protocol, we've already called tinyusb_enable_interface2(reserve_endpoints=true)
+    uint8_t ep_in = tinyusb_interface_protocol == HID_ITF_PROTOCOL_KEYBOARD ? 1 : tinyusb_get_free_in_endpoint();
     TU_VERIFY (ep_in != 0);
-    uint8_t ep_out = tinyusb_get_free_out_endpoint();
+    uint8_t ep_out = tinyusb_interface_protocol == HID_ITF_PROTOCOL_KEYBOARD ? 1 : tinyusb_get_free_out_endpoint();
     TU_VERIFY (ep_out != 0);
     uint8_t descriptor[TUD_HID_INOUT_DESC_LEN] = {
         // HID Input & Output descriptor
         // Interface number, string index, protocol, report descriptor len, EP OUT & IN address, size & polling interval
-        TUD_HID_INOUT_DESCRIPTOR(*itf, str_index, HID_ITF_PROTOCOL_NONE, tinyusb_hid_device_descriptor_len, ep_out, (uint8_t)(0x80 | ep_in), 64, 1)
+        TUD_HID_INOUT_DESCRIPTOR(*itf, str_index, tinyusb_interface_protocol, tinyusb_hid_device_descriptor_len, ep_out, (uint8_t)(0x80 | ep_in), 64, 1)
     };
     *itf+=1;
     memcpy(dst, descriptor, TUD_HID_INOUT_DESC_LEN);
@@ -275,14 +277,15 @@ void tud_hid_set_report_cb(uint8_t instance, uint8_t report_id, hid_report_type_
     }
 }
 
-USBHID::USBHID(){
+USBHID::USBHID(hid_interface_protocol_enum_t itf_protocol){
     if(!tinyusb_hid_devices_is_initialized){
         tinyusb_hid_devices_is_initialized = true;
         for(uint8_t i=0; i<USB_HID_DEVICES_MAX; i++){
             memset(&tinyusb_hid_devices[i], 0, sizeof(tinyusb_hid_device_t));
         }
         tinyusb_hid_devices_num = 0;
-        tinyusb_enable_interface(USB_INTERFACE_HID, TUD_HID_INOUT_DESC_LEN, tusb_hid_load_descriptor);
+        tinyusb_interface_protocol = itf_protocol;
+        tinyusb_enable_interface2(USB_INTERFACE_HID, TUD_HID_INOUT_DESC_LEN, tusb_hid_load_descriptor, itf_protocol == HID_ITF_PROTOCOL_KEYBOARD);
     }
 }
 
@@ -327,11 +330,16 @@ bool USBHID::SendReport(uint8_t id, const void* data, size_t len, uint32_t timeo
         return false;
     }
 
+    // If we're configured to support boot protocol, and the host has requested boot protocol, prevent
+    // sending of report ID, by passing report ID of 0 to tud_hid_n_report().
+    uint8_t effective_id = ((tinyusb_interface_protocol != HID_ITF_PROTOCOL_NONE) &&
+        (tud_hid_n_get_protocol(0) == HID_PROTOCOL_BOOT)) ? 0 : id;
+
     bool res = ready();
     if(!res){
         log_e("not ready");
     } else {
-        res = tud_hid_n_report(0, id, data, len);
+        res = tud_hid_n_report(0, effective_id, data, len);
         if(!res){
             log_e("report %u failed", id);
         } else {

libraries/USB/src/USBHID.h

@@ -66,7 +66,7 @@ class USBHIDDevice
 class USBHID
 {
 public:
-    USBHID(void);
+    USBHID(hid_interface_protocol_enum_t itf_protocol = HID_ITF_PROTOCOL_NONE);
     void begin(void);
     void end(void);
     bool ready(void);

libraries/USB/src/USBHIDKeyboard.cpp

@@ -32,7 +32,7 @@ static const uint8_t report_descriptor[] = {
     TUD_HID_REPORT_DESC_KEYBOARD(HID_REPORT_ID(HID_REPORT_ID_KEYBOARD))
 };
 
-USBHIDKeyboard::USBHIDKeyboard(): hid(){
+USBHIDKeyboard::USBHIDKeyboard(): hid(HID_ITF_PROTOCOL_KEYBOARD), shiftKeyReports(true){
     static bool initialized = false;
     if(!initialized){
         initialized = true;
@@ -80,6 +80,11 @@ void USBHIDKeyboard::sendReport(KeyReport* keys)
     hid.SendReport(HID_REPORT_ID_KEYBOARD, &report, sizeof(report));
 }
 
+void USBHIDKeyboard::setShiftKeyReports(bool set)
+{
+    shiftKeyReports = set;
+}
+
 #define SHIFT 0x80
 const uint8_t _asciimap[128] =
 {
@@ -285,7 +290,12 @@ size_t USBHIDKeyboard::press(uint8_t k)
             return 0;
         }
         if (k & 0x80) {                     // it's a capital letter or other character reached with shift
-            _keyReport.modifiers |= 0x02;   // the left shift modifier
+            // At boot, some PCs need a separate report with the shift key down like a real keyboard.
+            if (shiftKeyReports) {
+                pressRaw(HID_KEY_SHIFT_LEFT);
+            } else {
+                _keyReport.modifiers |= 0x02;   // the left shift modifier
+            }
             k &= 0x7F;
         }
     }
@@ -308,8 +318,13 @@ size_t USBHIDKeyboard::release(uint8_t k)
             return 0;
         }
         if (k & 0x80) {                         // it's a capital letter or other character reached with shift
-            _keyReport.modifiers &= ~(0x02);    // the left shift modifier
-            k &= 0x7F;
+            if (shiftKeyReports) {
+                releaseRaw(k & 0x7F);           // Release key without shift modifier
+                k = HID_KEY_SHIFT_LEFT;         // Below, release shift modifier
+            } else {
+                _keyReport.modifiers &= ~(0x02);    // the left shift modifier
+                k &= 0x7F;
+            }
         }
     }
     return releaseRaw(k);

libraries/USB/src/USBHIDKeyboard.h

@@ -114,6 +114,7 @@ class USBHIDKeyboard: public USBHIDDevice, public Print
 private:
     USBHID hid;
     KeyReport _keyReport;
+    bool shiftKeyReports;
 public:
     USBHIDKeyboard(void);
     void begin(void);
@@ -124,6 +125,7 @@ class USBHIDKeyboard: public USBHIDDevice, public Print
     size_t release(uint8_t k);
     void releaseAll(void);
     void sendReport(KeyReport* keys);
+    void setShiftKeyReports(bool set);
 
     //raw functions work with TinyUSB's HID_KEY_* macros
     size_t pressRaw(uint8_t k);