USB Stream: Make RX and TX buffer sizes configurable

Previously the USB Stream buffer sizes were fixed at
USB_MAX_PACKET_SIZE (currently 64 bytes).  But that
ended up using up too much packet RAM, a very limited
resource.  This change makes them configurable and
adds asserts to insure that the sizes are valid for
the underlying hardware.

Signed-off-by: Anton Staaf <robotboy@chromium.org>

BRANCH=None
BUG=None
TEST=make buildall -j
     Verify that USART forwarding on discovery works

Change-Id: Ib19c0dcfa9b16f23c1d72a5a7fc18026ab103f05
Reviewed-on: https://chromium-review.googlesource.com/255232
Trybot-Ready: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>

3 files changed, 38 insertions, 8 deletions

diff --git a/board/discovery-stm32f072/echo.c b/board/discovery-stm32f072/echo.c
index 56f99a1ddf..56fbef7bbe 100644
--- a/board/discovery-stm32f072/echo.c
+++ b/board/discovery-stm32f072/echo.c
@@ -75,6 +75,8 @@ USB_STREAM_CONFIG(usb_stream1,
 		  USB_IFACE_STREAM,
 		  USB_STR_STREAM_NAME,
 		  USB_EP_STREAM,
+		  64,
+		  64,
 		  usb_rx_queue,
 		  usb_tx_queue,
 		  usb_in.consumer,
diff --git a/chip/stm32/usb-stream.c b/chip/stm32/usb-stream.c
index 42d9d3774c..05351a8ca3 100644
--- a/chip/stm32/usb-stream.c
+++ b/chip/stm32/usb-stream.c
@@ -36,7 +36,7 @@ static size_t tx_write(struct usb_stream_config const *config)
 {
 	size_t count = consumer_read_memcpy(&config->consumer,
 					    config->tx_ram,
-					    USB_MAX_PACKET_SIZE,
+					    config->tx_size,
 					    memcpy_to_usbram);
 
 	btable_ep[config->endpoint].tx_count = count;
@@ -120,6 +120,14 @@ void usb_stream_rx(struct usb_stream_config const *config)
 	}
 }
 
+static usb_uint usb_ep_rx_size(size_t bytes)
+{
+	if (bytes < 64)
+		return bytes << 9;
+	else
+		return 0x8000 | ((bytes - 32) << 5);
+}
+
 void usb_stream_reset(struct usb_stream_config const *config)
 {
 	int i = config->endpoint;
@@ -128,7 +136,7 @@ void usb_stream_reset(struct usb_stream_config const *config)
 	btable_ep[i].tx_count = 0;
 
 	btable_ep[i].rx_addr  = usb_sram_addr(config->rx_ram);
-	btable_ep[i].rx_count = 0x8000 | ((USB_MAX_PACKET_SIZE / 32 - 1) << 10);
+	btable_ep[i].rx_count = usb_ep_rx_size(config->rx_size);
 
 	config->state->rx_waiting = 0;
 
diff --git a/chip/stm32/usb-stream.h b/chip/stm32/usb-stream.h
index 06374676f9..cca1523ab1 100644
--- a/chip/stm32/usb-stream.h
+++ b/chip/stm32/usb-stream.h
@@ -51,6 +51,9 @@ struct usb_stream_config {
 	 */
 	int endpoint;
 
+	size_t rx_size;
+	size_t tx_size;
+
 	usb_uint *rx_ram;
 	usb_uint *tx_ram;
 
@@ -81,6 +84,10 @@ extern struct producer_ops const usb_stream_producer_ops;
  * ENDPOINT is the index of the USB bulk endpoint used for receiving and
  * transmitting bytes.
  *
+ * RX_SIZE and TX_SIZE are the number of bytes of USB packet RAM to allocate
+ * for the RX and TX packets respectively.  The valid values for these
+ * parameters are dictated by the USB peripheral.
+ *
  * RX_QUEUE and TX_QUEUE are the names of the RX and TX queues that this driver
  * should write to and read from respectively.  They must match the queues
  * that the CONSUMER and PRODUCER read from and write to respectively.
@@ -92,8 +99,8 @@ extern struct producer_ops const usb_stream_producer_ops;
  * The following assertions can not be made because they require access to
  * non-const fields, but should be kept in mind.
  *
- * BUILD_ASSERT(RX_QUEUE.buffer_units >= USB_MAX_PACKET_SIZE);
- * BUILD_ASSERT(TX_QUEUE.buffer_units >= USB_MAX_PACKET_SIZE);
+ * BUILD_ASSERT(RX_QUEUE.buffer_units >= RX_SIZE);
+ * BUILD_ASSERT(TX_QUEUE.buffer_units >= TX_SIZE);
  * BUILD_ASSERT(RX_QUEUE.unit_bytes == 1);
  * BUILD_ASSERT(TX_QUEUE.unit_bytes == 1);
  * BUILD_ASSERT(PRODUCER.queue == &TX_QUEUE);
@@ -103,17 +110,30 @@ extern struct producer_ops const usb_stream_producer_ops;
 			  INTERFACE,					\
 			  INTERFACE_NAME,				\
 			  ENDPOINT,					\
+			  RX_SIZE,					\
+			  TX_SIZE,					\
 			  RX_QUEUE,					\
 			  TX_QUEUE,					\
 			  CONSUMER,					\
 			  PRODUCER)					\
 									\
-	static usb_uint CONCAT2(NAME, _ep_rx_buffer)[USB_MAX_PACKET_SIZE / 2] __usb_ram; \
-	static usb_uint CONCAT2(NAME, _ep_tx_buffer)[USB_MAX_PACKET_SIZE / 2] __usb_ram; \
+	BUILD_ASSERT(RX_SIZE <= USB_MAX_PACKET_SIZE);			\
+	BUILD_ASSERT(TX_SIZE <= USB_MAX_PACKET_SIZE);			\
+	BUILD_ASSERT(RX_SIZE > 0);					\
+	BUILD_ASSERT(TX_SIZE > 0);					\
+	BUILD_ASSERT((RX_SIZE <   64 && (RX_SIZE & 0x01) == 0) ||	\
+		     (RX_SIZE < 1024 && (RX_SIZE & 0x1f) == 0));	\
+	BUILD_ASSERT((TX_SIZE <   64 && (TX_SIZE & 0x01) == 0) ||	\
+		     (TX_SIZE < 1024 && (TX_SIZE & 0x1f) == 0));	\
+									\
+	static usb_uint CONCAT2(NAME, _ep_rx_buffer)[RX_SIZE / 2] __usb_ram; \
+	static usb_uint CONCAT2(NAME, _ep_tx_buffer)[TX_SIZE / 2] __usb_ram; \
 	static struct usb_stream_state CONCAT2(NAME, _state);		\
 	struct usb_stream_config const NAME = {				\
 		.state    = &CONCAT2(NAME, _state),			\
 		.endpoint = ENDPOINT,					\
+		.rx_size  = RX_SIZE,					\
+		.tx_size  = TX_SIZE,					\
 		.rx_ram   = CONCAT2(NAME, _ep_rx_buffer),		\
 		.tx_ram   = CONCAT2(NAME, _ep_tx_buffer),		\
 		.consumer = {						\
@@ -145,7 +165,7 @@ extern struct producer_ops const usb_stream_producer_ops;
 		.bDescriptorType  = USB_DT_ENDPOINT,			\
 		.bEndpointAddress = 0x80 | ENDPOINT,			\
 		.bmAttributes     = 0x02 /* Bulk IN */,			\
-		.wMaxPacketSize   = USB_MAX_PACKET_SIZE,		\
+		.wMaxPacketSize   = TX_SIZE,				\
 		.bInterval        = 10,					\
 	};								\
 	const struct usb_endpoint_descriptor				\
@@ -154,7 +174,7 @@ extern struct producer_ops const usb_stream_producer_ops;
 		.bDescriptorType  = USB_DT_ENDPOINT,			\
 		.bEndpointAddress = ENDPOINT,				\
 		.bmAttributes     = 0x02 /* Bulk OUT */,		\
-		.wMaxPacketSize   = USB_MAX_PACKET_SIZE,		\
+		.wMaxPacketSize   = RX_SIZE,				\
 		.bInterval        = 0,					\
 	};								\
 	static void CONCAT2(NAME, _ep_tx)(void)				\