Merge branch 'bug/usb-full-ep'

This resolves issues related to sending full (64B) packets via USB
2.0. In this case, some hosts continue to expect more data. Add
infrastructure for sending 0-byte packets to signal end of
transmission, and use it in SerialUSB.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

2 files changed, 38 insertions, 31 deletions

diff --git a/libmaple/include/libmaple/usb_cdcacm.h b/libmaple/include/libmaple/usb_cdcacm.h
index 8b3c1fe..5fe832c 100644
--- a/libmaple/include/libmaple/usb_cdcacm.h
+++ b/libmaple/include/libmaple/usb_cdcacm.h
@@ -72,6 +72,27 @@ extern "C" {
 #define USB_INTERFACE_SUBCLASS_CDC_ACM    0x02
 #define USB_INTERFACE_CLASS_DIC           0x0A
 
+/*
+ * Endpoint configuration
+ */
+
+#define USB_CDCACM_CTRL_ENDP            0
+#define USB_CDCACM_CTRL_RX_ADDR         0x40
+#define USB_CDCACM_CTRL_TX_ADDR         0x80
+#define USB_CDCACM_CTRL_EPSIZE          0x40
+
+#define USB_CDCACM_TX_ENDP              1
+#define USB_CDCACM_TX_ADDR              0xC0
+#define USB_CDCACM_TX_EPSIZE            0x40
+
+#define USB_CDCACM_MANAGEMENT_ENDP      2
+#define USB_CDCACM_MANAGEMENT_ADDR      0x100
+#define USB_CDCACM_MANAGEMENT_EPSIZE    0x40
+
+#define USB_CDCACM_RX_ENDP              3
+#define USB_CDCACM_RX_ADDR              0x110
+#define USB_CDCACM_RX_EPSIZE            0x40
+
 #ifndef __cplusplus
 #define USB_CDCACM_DECLARE_DEV_DESC(vid, pid)                           \
   {                                                                     \
@@ -106,6 +127,7 @@ uint32 usb_cdcacm_peek(uint8* buf, uint32 len);
 
 uint32 usb_cdcacm_data_available(void); /* in RX buffer */
 uint16 usb_cdcacm_get_pending(void);
+uint8 usb_cdcacm_is_transmitting(void);
 
 uint8 usb_cdcacm_get_dtr(void);
 uint8 usb_cdcacm_get_rts(void);
diff --git a/libmaple/usb/stm32f1/usb_cdcacm.c b/libmaple/usb/stm32f1/usb_cdcacm.c
index addab3c..ecb9397 100644
--- a/libmaple/usb/stm32f1/usb_cdcacm.c
+++ b/libmaple/usb/stm32f1/usb_cdcacm.c
@@ -82,27 +82,6 @@ static void usbSetConfiguration(void);
 static void usbSetDeviceAddress(void);
 
 /*
- * Endpoint configuration
- */
-
-#define USB_CDCACM_CTRL_ENDP            0
-#define USB_CDCACM_CTRL_RX_ADDR         0x40
-#define USB_CDCACM_CTRL_TX_ADDR         0x80
-#define USB_CDCACM_CTRL_EPSIZE          0x40
-
-#define USB_CDCACM_TX_ENDP              1
-#define USB_CDCACM_TX_ADDR              0xC0
-#define USB_CDCACM_TX_EPSIZE            0x40
-
-#define USB_CDCACM_MANAGEMENT_ENDP      2
-#define USB_CDCACM_MANAGEMENT_ADDR      0x100
-#define USB_CDCACM_MANAGEMENT_EPSIZE    0x40
-
-#define USB_CDCACM_RX_ENDP              3
-#define USB_CDCACM_RX_ADDR              0x110
-#define USB_CDCACM_RX_EPSIZE            0x40
-
-/*
  * Descriptors
  */
 
@@ -288,6 +267,8 @@ static volatile uint8 vcomBufferRx[USB_CDCACM_RX_EPSIZE];
 static volatile uint32 rx_offset = 0;
 /* Number of bytes left to transmit */
 static volatile uint32 n_unsent_bytes = 0;
+/* Are we currently sending an IN packet? */
+static volatile uint8 transmitting = 0;
 /* Number of unread bytes */
 static volatile uint32 n_unread_bytes = 0;
 
@@ -413,7 +394,7 @@ void usb_cdcacm_putc(char ch) {
  * buffer, and returns the number of bytes copied. */
 uint32 usb_cdcacm_tx(const uint8* buf, uint32 len) {
     /* Last transmission hasn't finished, so abort. */
-    if (n_unsent_bytes) {
+    if (usb_cdcacm_is_transmitting()) {
         return 0;
     }
 
@@ -425,10 +406,14 @@ uint32 usb_cdcacm_tx(const uint8* buf, uint32 len) {
     /* Queue bytes for sending. */
     if (len) {
         usb_copy_to_pma(buf, len, USB_CDCACM_TX_ADDR);
-        usb_set_ep_tx_count(USB_CDCACM_TX_ENDP, len);
-        n_unsent_bytes = len;
-        usb_set_ep_tx_stat(USB_CDCACM_TX_ENDP, USB_EP_STAT_TX_VALID);
     }
+    // We still need to wait for the interrupt, even if we're sending
+    // zero bytes. (Sending zero-size packets is useful for flushing
+    // host-side buffers.)
+    usb_set_ep_tx_count(USB_CDCACM_TX_ENDP, len);
+    n_unsent_bytes = len;
+    transmitting = 1;
+    usb_set_ep_tx_stat(USB_CDCACM_TX_ENDP, USB_EP_STAT_TX_VALID);
 
     return len;
 }
@@ -437,7 +422,11 @@ uint32 usb_cdcacm_data_available(void) {
     return n_unread_bytes;
 }
 
-uint16 usb_cdcacm_get_pending() {
+uint8 usb_cdcacm_is_transmitting(void) {
+    return transmitting;
+}
+
+uint16 usb_cdcacm_get_pending(void) {
     return n_unsent_bytes;
 }
 
@@ -518,12 +507,8 @@ int usb_cdcacm_get_n_data_bits(void) {
  */
 
 static void vcomDataTxCb(void) {
-    /* The following assumes that all of the bytes we copied during
-     * the last call to usb_cdcacm_tx were sent during the IN
-     * transaction (this seems to be the case). */
-    /* TODO find out why this is broken:
-     * n_unsent_bytes = usb_get_ep_tx_count(USB_CDCACM_TX_ENDP); */
     n_unsent_bytes = 0;
+    transmitting = 0;
 }
 
 static void vcomDataRxCb(void) {