Add WebUSB platform descriptor

Adds a WebUSB platform descriptor to the BOS descriptor
and a landing page pointing to https://code.pybricks.com.

Signed-off-by: Nate Karstens <[email protected]>

Author: nkarstens

lib/pbio/drv/usb/stm32_usbd/usbd_desc.c

@@ -74,7 +74,7 @@ static const char software_version[] = PBIO_PROTOCOL_VERSION_STR;
 #define  USB_DEV_CAP_TYPE_PLATFORM   (5)
 
 #define  USB_SIZ_STRING_SERIAL       0x1A
-#define  USB_SIZ_BOS_DESC_CONST      (5 + 28)
+#define  USB_SIZ_BOS_DESC_CONST      (5 + 28 + 24)
 #define  USB_SIZ_UUID                (128 / 8)
 #define  USB_SIZ_PLATFORM_HDR        (4 + USB_SIZ_UUID)
 #define  USB_SIZ_HUB_NAME_MAX        (16)
@@ -118,7 +118,7 @@ __ALIGN_BEGIN static uint8_t USBD_BOSDesc[USB_SIZ_BOS_DESC] __ALIGN_END =
     USB_DESC_TYPE_BOS,          /* bDescriptorType = BOS */
     LOBYTE(USB_SIZ_BOS_DESC),   /* wTotalLength */
     HIBYTE(USB_SIZ_BOS_DESC),   /* wTotalLength */
-    1,                          /* bNumDeviceCaps */
+    2,                          /* bNumDeviceCaps */
 
     28,                         /* bLength */
     USB_DEVICE_CAPABITY_TYPE,   /* bDescriptorType = Device Capability */
@@ -141,7 +141,29 @@ __ALIGN_BEGIN static uint8_t USBD_BOSDesc[USB_SIZ_BOS_DESC] __ALIGN_END =
     LOBYTE(USBD_SIZ_MS_OS_DSCRPTR_SET), /* wMSOSDescriptorSetTotalLength */
     HIBYTE(USBD_SIZ_MS_OS_DSCRPTR_SET), /* wMSOSDescriptorSetTotalLength */
     USBD_MS_VENDOR_CODE,              /* bMS_VendorCode */
-    0x00                              /* bAltEnumCode = Does not support alternate enumeration */
+    0x00,                             /* bAltEnumCode = Does not support alternate enumeration */
+
+    24,                         /* bLength */
+    USB_DEVICE_CAPABITY_TYPE,   /* bDescriptorType = Device Capability */
+    USB_DEV_CAP_TYPE_PLATFORM,  /* bDevCapabilityType */
+    0x00,                       /* bReserved */
+
+    /*
+     * PlatformCapabilityUUID
+     * WebUSB Platform Capability descriptor
+     * 3408B638-09A9-47A0-8BFD-A0768815B665
+     * RFC 4122 explains the correct byte ordering
+     */
+    0x38, 0xB6, 0x08, 0x34,           /* 32-bit value */
+    0xA9, 0x09,                       /* 16-bit value */
+    0xA0, 0x47,                       /* 16-bit value */
+    0x8B, 0xFD,
+    0xA0, 0x76, 0x88, 0x15, 0xB6, 0x65,
+
+    LOBYTE(0x0100),                   /* bcdVersion */
+    HIBYTE(0x0100),                   /* bcdVersion */
+    USBD_WEBUSB_VENDOR_CODE,          /* bVendorCode */
+    USBD_WEBUSB_LANDING_PAGE_IDX      /* iLandingPage */
 };
 
 static uint16_t USBD_BOSDesc_Len;

lib/pbio/drv/usb/stm32_usbd/usbd_pybricks.c

@@ -155,6 +155,18 @@ __ALIGN_BEGIN static uint8_t USBD_Pybricks_CfgDesc[USBD_PYBRICKS_CONFIG_DESC_SIZ
     0x00                                      /* bInterval */
 };
 
+__ALIGN_BEGIN static const uint8_t WebUSB_DescSet[20] __ALIGN_END =
+{
+    20,    /* bLength */
+    0x03,  /* bDescriptorType = URL */
+    0x01,  /* bScheme = https:// */
+
+    /* URL */
+    'c', 'o', 'd', 'e', '.',
+    'p', 'y', 'b', 'r', 'i', 'c', 'k', 's', '.',
+    'c', 'o', 'm'
+};
+
 /**
   * @}
   */
@@ -248,6 +260,14 @@ static USBD_StatusTypeDef USBD_Pybricks_Setup(USBD_HandleTypeDef *pdev,
                         MIN(sizeof(USBD_OSDescSet), req->wLength));
                     break;
 
+                case USBD_WEBUSB_VENDOR_CODE:
+                    if ((req->wValue == USBD_WEBUSB_LANDING_PAGE_IDX) && (req->wIndex == 0x02)) {
+                        (void)USBD_CtlSendData(pdev,
+                            (uint8_t *)WebUSB_DescSet,
+                            MIN(sizeof(WebUSB_DescSet), req->wLength));
+                    }
+                    break;
+
                 default:
                     USBD_CtlError(pdev, req);
                     ret = USBD_FAIL;

lib/pbio/drv/usb/stm32_usbd/usbd_pybricks.h

@@ -41,8 +41,12 @@ extern "C" {
   * @{
   */
 #define USBD_MS_VENDOR_CODE                0x01
+#define USBD_WEBUSB_VENDOR_CODE            0x02
+
 #define USBD_SIZ_MS_OS_DSCRPTR_SET         (10 + 20 + 132)
 
+#define USBD_WEBUSB_LANDING_PAGE_IDX       1
+
 #define USBD_PYBRICKS_CONFIG_DESC_SIZ      (9 + 9 + 7 + 7)
 
 #define USBD_PYBRICKS_IN_EP                0x81U  /* EP1 for data IN */