From cf6fdbdca0e32b98074843803e5760cd6fa9fbde Mon Sep 17 00:00:00 2001
From: Tilman Sauerbeck <tilman@code-monkey.de>
Date: Wed, 3 Jul 2019 06:04:02 +0200
Subject: [PATCH] common: Implement the receive path for the USB serial module.

This sets up a ringbuffer for data received from the USB host.
When we try to read from the empty ringbuffer, another receive-data
request is sent.

Other modules can read from this ringbuffer via the new
usb_serial_read() function.
---
 src/common/virtual_com.c | 42 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/src/common/virtual_com.c b/src/common/virtual_com.c
index abf0a32..faa3b67 100644
--- a/src/common/virtual_com.c
+++ b/src/common/virtual_com.c
@@ -52,6 +52,8 @@
 #include "usb_phy.h"
 #endif
 
+#include "ringbuf.h"
+
 /* Provided by users. */
 extern void USB_DeviceClockInit(void);
 extern void USB_DeviceIsrEnable(void);
@@ -62,6 +64,12 @@ extern void USB_DeviceIsrEnable(void);
 /*******************************************************************************
 * Variables
 ******************************************************************************/
+
+static uint8_t cdc_rx_buf_space[1024];
+
+static struct ringbuf cdc_rx_buf =
+	RINGBUF_INIT (cdc_rx_buf_space, sizeof (cdc_rx_buf_space));
+
 /* Data structure of virtual com device */
 usb_cdc_vcom_struct_t s_cdcVcom;
 
@@ -152,6 +160,7 @@ usb_status_t USB_DeviceCdcAcmBulkIn(usb_device_handle handle,
         {
             /* User: add your own code for send complete event */
             s_sendComplete = 1;
+			USB_DeviceRecvRequest (handle, USB_CDC_VCOM_BULK_OUT_ENDPOINT, s_currRecvBuf, s_usbBulkMaxPacketSize);
 #if defined(FSL_FEATURE_USB_KHCI_KEEP_ALIVE_ENABLED) && (FSL_FEATURE_USB_KHCI_KEEP_ALIVE_ENABLED > 0U) && \
     defined(USB_DEVICE_CONFIG_KEEP_ALIVE_MODE) && (USB_DEVICE_CONFIG_KEEP_ALIVE_MODE > 0U) &&             \
     defined(FSL_FEATURE_USB_KHCI_USB_RAM) && (FSL_FEATURE_USB_KHCI_USB_RAM > 0U)
@@ -197,6 +206,18 @@ usb_status_t USB_DeviceCdcAcmBulkOut(usb_device_handle handle,
     defined(FSL_FEATURE_USB_KHCI_USB_RAM) && (FSL_FEATURE_USB_KHCI_USB_RAM > 0U)
         USB0->INTEN |= USB_INTEN_SOFTOKEN_MASK;
 #endif
+
+		if (s_recvSize) {
+			for (uint32_t offset = 0; s_recvSize-- > 0; offset++) {
+				if (ringbuf_is_full (&cdc_rx_buf))
+					break;
+
+				ringbuf_write (&cdc_rx_buf, s_currRecvBuf[offset]);
+			}
+
+			s_recvSize = 0;
+		} else
+
         if (!s_recvSize)
         {
 #if defined(FSL_FEATURE_USB_KHCI_KEEP_ALIVE_ENABLED) && (FSL_FEATURE_USB_KHCI_KEEP_ALIVE_ENABLED > 0U) && \
@@ -204,6 +225,8 @@ usb_status_t USB_DeviceCdcAcmBulkOut(usb_device_handle handle,
     defined(FSL_FEATURE_USB_KHCI_USB_RAM) && (FSL_FEATURE_USB_KHCI_USB_RAM > 0U)
             USB0->INTEN &= ~USB_INTEN_SOFTOKEN_MASK;
 #endif
+
+			USB_DeviceRecvRequest (handle, USB_CDC_VCOM_BULK_OUT_ENDPOINT, s_currRecvBuf, s_usbBulkMaxPacketSize);
         }
     }
     else
@@ -538,6 +561,8 @@ usb_status_t USB_DeviceCallback(usb_device_handle handle, uint32_t event, void *
                     {
                         s_usbBulkMaxPacketSize = FS_CDC_VCOM_BULK_OUT_PACKET_SIZE;
                     }
+
+					USB_DeviceRecvRequest (handle, USB_CDC_VCOM_BULK_OUT_ENDPOINT, s_currRecvBuf, s_usbBulkMaxPacketSize);
                 }
             }
             break;
@@ -690,3 +715,20 @@ USB0_IRQHandler (void)
 {
 	USB_DeviceKhciIsrFunction (s_cdcVcom.deviceHandle);
 }
+
+bool usb_serial_read (char *c)
+{
+	if (ringbuf_is_empty (&cdc_rx_buf)) {
+		if (!s_recvSize || s_recvSize == (uint32_t) -1)
+			USB_DeviceRecvRequest (s_cdcVcom.deviceHandle,
+			                       USB_CDC_VCOM_BULK_OUT_ENDPOINT,
+			                       s_currRecvBuf,
+			                       s_usbBulkMaxPacketSize);
+
+		return false;
+	}
+
+	*c = ringbuf_read (&cdc_rx_buf);
+
+	return true;
+}
-- 
2.30.2