stm32/usbdev: Simplify HID tx/rx buffer passing.

ports/stm32/usbd_hid_interface.c

@@ -42,25 +42,24 @@
 #include "irq.h"
 #include "usb.h"
 
-void usbd_hid_init(usbd_hid_itf_t *hid, USBD_HandleTypeDef *pdev) {
+uint8_t *usbd_hid_init(usbd_hid_itf_t *hid, USBD_HandleTypeDef *pdev) {
     hid->usb = pdev;
     hid->current_read_buffer = 0;
     hid->last_read_len = 0;
     hid->current_write_buffer = 0;
-    USBD_HID_SetRxBuffer(pdev, hid->buffer[hid->current_write_buffer]);
+
+    // Return the buffer to place the first USB OUT packet
+    return hid->buffer[hid->current_write_buffer];
 }
 
 // Data received over USB OUT endpoint is processed here.
-// buf: Buffer of data received
-// len: Number of data received (in bytes)
+// len: number of bytes received into the buffer we passed to USBD_HID_ReceivePacket
 // Returns USBD_OK if all operations are OK else USBD_FAIL
-// The buffer we are passed here is just hid->buffer, so we are free to modify it.
-int8_t usbd_hid_receive(usbd_hid_itf_t *hid, size_t len, uint8_t *buf) {
+int8_t usbd_hid_receive(usbd_hid_itf_t *hid, size_t len) {
     hid->current_write_buffer = !hid->current_write_buffer;
     hid->last_read_len = len;
     // initiate next USB packet transfer, to append to existing data in buffer
-    USBD_HID_SetRxBuffer(hid->usb, hid->buffer[hid->current_write_buffer]);
-    USBD_HID_ReceivePacket(hid->usb);
+    USBD_HID_ReceivePacket(hid->usb, hid->buffer[hid->current_write_buffer]);
     // Set NAK to indicate we need to process read buffer
     USBD_HID_SetNAK(hid->usb);
     return USBD_OK;

ports/stm32/usbdev/class/inc/usbd_cdc_msc_hid.h

@@ -98,8 +98,7 @@ uint8_t USBD_CDC_TransmitPacket(USBD_HandleTypeDef *pdev, size_t len, const uint
 
 uint8_t USBD_MSC_RegisterStorage(USBD_HandleTypeDef *pdev, USBD_StorageTypeDef *fops);
 
-uint8_t USBD_HID_SetRxBuffer(USBD_HandleTypeDef *pdev, uint8_t *pbuff);
-uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev);
+uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev, uint8_t *buf);
 int USBD_HID_CanSendReport(USBD_HandleTypeDef *pdev);
 uint8_t USBD_HID_SendReport(USBD_HandleTypeDef *pdev, uint8_t *report, uint16_t len);
 uint8_t USBD_HID_SetNAK(USBD_HandleTypeDef *pdev);
@@ -113,7 +112,7 @@ int8_t usbd_cdc_receive(struct _usbd_cdc_itf_t *cdc, size_t len);
 
 // These are provided externally to implement the HID interface
 struct _usbd_hid_itf_t;
-void usbd_hid_init(struct _usbd_hid_itf_t *hid, USBD_HandleTypeDef *pdev);
-int8_t usbd_hid_receive(struct _usbd_hid_itf_t *hid, size_t len, uint8_t *buf);
+uint8_t *usbd_hid_init(struct _usbd_hid_itf_t *hid, USBD_HandleTypeDef *pdev);
+int8_t usbd_hid_receive(struct _usbd_hid_itf_t *hid, size_t len);
 
 #endif // _USB_CDC_MSC_CORE_H_

ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c

@@ -82,8 +82,6 @@ typedef struct {
     uint32_t             IdleState;
     uint32_t             AltSetting;
     HID_StateTypeDef     state;
-    uint8_t              *RxBuffer;
-    uint32_t             RxLength;
 } USBD_HID_HandleTypeDef;
 
 static uint8_t usbd_mode;
@@ -724,10 +722,10 @@ static uint8_t USBD_CDC_MSC_HID_Init(USBD_HandleTypeDef *pdev, uint8_t cfgidx) {
                        USBD_EP_TYPE_INTR,
                        mps_out);
 
-        usbd_hid_init(state->hid, pdev);
+        uint8_t *buf = usbd_hid_init(state->hid, pdev);
 
         // Prepare Out endpoint to receive next packet
-        USBD_LL_PrepareReceive(pdev, hid_out_ep, HID_ClassData.RxBuffer, mps_out);
+        USBD_LL_PrepareReceive(pdev, hid_out_ep, buf, mps_out);
 
         HID_ClassData.state = HID_IDLE;
     }
@@ -973,8 +971,8 @@ static uint8_t USBD_CDC_MSC_HID_DataOut(USBD_HandleTypeDef *pdev, uint8_t epnum)
         MSC_BOT_DataOut(pdev, epnum);
         return USBD_OK;
     } else if ((usbd_mode & USBD_MODE_HID) && epnum == (hid_out_ep & 0x7f)) {
-        HID_ClassData.RxLength = USBD_LL_GetRxDataSize(pdev, epnum);
-        usbd_hid_receive(state->hid, HID_ClassData.RxLength, HID_ClassData.RxBuffer);
+        size_t len = USBD_LL_GetRxDataSize(pdev, epnum);
+        usbd_hid_receive(state->hid, len);
     }
 
     return USBD_OK;
@@ -1032,13 +1030,8 @@ uint8_t USBD_MSC_RegisterStorage(USBD_HandleTypeDef *pdev, USBD_StorageTypeDef *
     }
 }
 
-uint8_t USBD_HID_SetRxBuffer(USBD_HandleTypeDef *pdev, uint8_t *pbuff) {
-    HID_ClassData.RxBuffer = pbuff;
-    return USBD_OK;
-}
-
 // prepare OUT endpoint for reception
-uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev) {
+uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev, uint8_t *buf) {
     // Suspend or Resume USB Out process
     if (pdev->dev_speed == USBD_SPEED_HIGH) {
         return USBD_FAIL;
@@ -1048,7 +1041,7 @@ uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev) {
     uint16_t mps_out =
         hid_desc[HID_DESC_OFFSET_MAX_PACKET_OUT_LO]
         | (hid_desc[HID_DESC_OFFSET_MAX_PACKET_OUT_HI] << 8);
-    USBD_LL_PrepareReceive(pdev, hid_out_ep, HID_ClassData.RxBuffer, mps_out);
+    USBD_LL_PrepareReceive(pdev, hid_out_ep, buf, mps_out);
 
     return USBD_OK;
 }