From 0883a7e72f7122b307798205441c96120446bf75 Mon Sep 17 00:00:00 2001
From: Pavol Rusnak
Date: Tue, 17 Jan 2017 20:17:15 +0100
Subject: stmhal: Implement SNAK/CNAK mechanism for USB HID receive.

This implements flow control in case user does not call recv method often
enough (it tells host side to stop sending more data).
---
 stmhal/usbdev/class/src/usbd_cdc_msc_hid.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

(limited to 'stmhal/usbdev/class/src')

diff --git a/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c b/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c
index 3ebc7d828..cfae7224d 100644
--- a/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c
+++ b/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c
@@ -1093,6 +1093,24 @@ uint8_t USBD_HID_SendReport(USBD_HandleTypeDef *pdev, uint8_t *report, uint16_t
     return USBD_OK;
 }
 
+uint8_t USBD_HID_SetNAK(USBD_HandleTypeDef *pdev) {
+    // get USBx object from pdev (needed for USBx_OUTEP macro below)
+    PCD_HandleTypeDef *hpcd = pdev->pData;
+    USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
+    // set NAK on HID OUT endpoint
+    USBx_OUTEP(HID_OUT_EP_WITH_CDC)->DOEPCTL |= USB_OTG_DOEPCTL_SNAK;
+    return USBD_OK;
+}
+
+uint8_t USBD_HID_ClearNAK(USBD_HandleTypeDef *pdev) {
+    // get USBx object from pdev (needed for USBx_OUTEP macro below)
+    PCD_HandleTypeDef *hpcd = pdev->pData;
+    USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
+    // clear NAK on HID OUT endpoint
+    USBx_OUTEP(HID_OUT_EP_WITH_CDC)->DOEPCTL |= USB_OTG_DOEPCTL_CNAK;
+    return USBD_OK;
+}
+
 // CDC/MSC/HID interface class callback structure
 USBD_ClassTypeDef USBD_CDC_MSC_HID = {
     USBD_CDC_MSC_HID_Init,
-- 
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