Enable USB string descriptors in the bootloader

Author: sandeepmistry

bootloaders/zero/sam_ba_usb.c

@@ -44,13 +44,8 @@ const char devDescriptor[] =
   USB_PID_HIGH,  // idProduct H
   0x00,   // bcdDevice L, here matching SAM-BA version
   0x02,   // bcdDevice H
-#if 0 // TODO: pending validation
   STRING_INDEX_MANUFACTURER,   // iManufacturer
   STRING_INDEX_PRODUCT,        // iProduct
-#else
-  0x00,   // iManufacturer
-  0x00,   // iProduct
-#endif // 0
   0x00,   // SerialNumber, should be based on product unique ID
   0x01    // bNumConfigs
 };
@@ -195,47 +190,40 @@ void sam_ba_usb_CDC_Enumerate(P_USB_CDC pCdc)
         /* Return Device Descriptor */
         USB_Write(pCdc->pUsb, devDescriptor, SAM_BA_MIN(sizeof(devDescriptor), wLength), USB_EP_CTRL);
       }
-      else
+      else if (wValue>>8 == STD_GET_DESCRIPTOR_CONFIGURATION)
       {
-        if (wValue>>8 == STD_GET_DESCRIPTOR_CONFIGURATION)
-        {
-          /* Return Configuration Descriptor */
-          USB_Write(pCdc->pUsb, cfgDescriptor, SAM_BA_MIN(sizeof(cfgDescriptor), wLength), USB_EP_CTRL);
-        }
-        else
+        /* Return Configuration Descriptor */
+        USB_Write(pCdc->pUsb, cfgDescriptor, SAM_BA_MIN(sizeof(cfgDescriptor), wLength), USB_EP_CTRL);
+      }
+      else if (wValue>>8 == STD_GET_DESCRIPTOR_STRING)
+      {
+        switch ( wValue & 0xff )
         {
-#if 0 // TODO: pending validation
-          if (wValue>>8 == STD_GET_DESCRIPTOR_STRING)
-          {
-            switch ( wValue & 0xff )
-            {
-              case STRING_INDEX_LANGUAGES:
-                uint16_t STRING_LANGUAGE[2] = { (STD_GET_DESCRIPTOR_STRING<<8) | 4, 0x0409 };
-
-                USB_Write(pCdc->pUsb, (const char*)STRING_LANGUAGE, SAM_BA_MIN(sizeof(STRING_LANGUAGE), wLength), USB_EP_CTRL);
-              break;
-
-              case STRING_INDEX_MANUFACTURER:
-                USB_SendString(pCdc->pUsb, STRING_MANUFACTURER, strlen(STRING_MANUFACTURER), wLength );
-              break;
-
-              case STRING_INDEX_PRODUCT:
-                USB_SendString(pCdc->pUsb, STRING_PRODUCT, strlen(STRING_PRODUCT), wLength );
-              break;
-              default:
-                /* Stall the request */
-                USB_SendStall(pUsb, true);
-              break;
-            }
+          case STRING_INDEX_LANGUAGES: {
+            uint16_t STRING_LANGUAGE[2] = { (STD_GET_DESCRIPTOR_STRING<<8) | 4, 0x0409 };
+
+            USB_Write(pCdc->pUsb, (const char*)STRING_LANGUAGE, SAM_BA_MIN(sizeof(STRING_LANGUAGE), wLength), USB_EP_CTRL);
           }
-          else
-#endif // 0
-          {
+          break;
+
+          case STRING_INDEX_MANUFACTURER:
+            USB_SendString(pCdc->pUsb, STRING_MANUFACTURER, wLength );
+          break;
+
+          case STRING_INDEX_PRODUCT:
+            USB_SendString(pCdc->pUsb, STRING_PRODUCT, wLength );
+          break;
+          default:
             /* Stall the request */
             USB_SendStall(pUsb, true);
-          }
+          break;
         }
       }
+      else
+      {
+        /* Stall the request */
+        USB_SendStall(pUsb, true);
+      }
     break;
 
     case STD_SET_ADDRESS:
@@ -430,27 +418,24 @@ P_USB_CDC usb_init(void)
   return &sam_ba_cdc;
 }
 
-#if 0 // TODO: pending validation
 /*----------------------------------------------------------------------------
  * \brief Send a USB descriptor string.
  *
  * The input string is plain ASCII but is sent out as UTF-16 with the correct 2-byte prefix.
  */
-uint32_t USB_SendString(Usb *pUsb, const char* ascii_string, uint8_t length, uint8_t maxLength)
+uint32_t USB_SendString(Usb *pUsb, const char* ascii_string, uint8_t maxLength)
 {
   uint8_t string_descriptor[255]; // Max USB-allowed string length
   uint16_t* unicode_string=(uint16_t*)(string_descriptor+2); // point on 3 bytes of descriptor
+  int resulting_length;
 
-  int resulting_length = 1;
+  string_descriptor[0] = (strlen(ascii_string)<<1) + 2;
+  string_descriptor[1] = STD_GET_DESCRIPTOR_STRING;
 
-  for ( ; *ascii_string && (length>=0) && (resulting_length<(maxLength>>1)) ; ascii_string++, length--, resulting_length++ )
+  for ( resulting_length = 1 ; *ascii_string && (resulting_length<maxLength>>1) ; resulting_length++ )
   {
-    *unicode_string++ = (uint16_t)(*ascii_string);
+    *unicode_string++ = (uint16_t)(*ascii_string++);
   }
 
-  string_descriptor[0] = (resulting_length<<1);
-  string_descriptor[1] = STD_GET_DESCRIPTOR_STRING;
-
-  return USB_Write(pUsb, (const char*)unicode_string, resulting_length, USB_EP_CTRL);
+  return USB_Write(pUsb, (const char*)string_descriptor, resulting_length<<1, USB_EP_CTRL);
 }
-#endif // 0

bootloaders/zero/sam_ba_usb.h

@@ -66,11 +66,9 @@
 #define FEATURE_DEVICE_REMOTE_WAKEUP   (1u)
 #define FEATURE_TEST_MODE              (2u)
 
-#if 0 // TODO: pending validation
 #define STRING_INDEX_LANGUAGES         (0x00u)
 #define STRING_INDEX_MANUFACTURER      (0x01u)
 #define STRING_INDEX_PRODUCT           (0x02u)
-#endif // 0
 
 #define SAM_BA_MIN(a, b) (((a) < (b)) ? (a) : (b))
 
@@ -96,9 +94,7 @@ P_USB_CDC usb_init(void);
 
 void sam_ba_usb_CDC_Enumerate(P_USB_CDC pCdc);
 
-#if 0 // TODO: pending validation
-uint32_t USB_SendString(Usb *pUsb, const char* ascii_string, uint8_t length, uint8_t maxLength);
-#endif // 0
+uint32_t USB_SendString(Usb *pUsb, const char* ascii_string, uint8_t maxLength);
 
 extern USB_CDC sam_ba_cdc;