CHERRY-PICK: usb: allow reading descriptors larger than 64 bytes

When a control transfer requests a descriptor larger than 64 bytes, we
need to do several IN transfers to get the proper packet sequence :
SETUP IN IN IN .. IN OUT(null)

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=samus
BUG=chrome-os-partner:32652
TEST=set USB_STR_VERSION to "012345678901234567890123456789ABCDEF",
then do "lsusb -v" on the host and check the USB transfers
with the protocol analyzer.

Change-Id: I5ddeede41bd39acf3619a620c7046c9fcad5bc7a
Original-Change-Id: I6940095008cb2a34c6896b337c5eda4fa267adc1
Reviewed-on: https://chromium-review.googlesource.com/222700
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Todd Broch <tbroch@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/229151
Reviewed-by: Mohammed Habibulla <moch@chromium.org>
Commit-Queue: Mohammed Habibulla <moch@chromium.org>
Tested-by: Mohammed Habibulla <moch@chromium.org>

1 files changed, 50 insertions, 29 deletions

diff --git a/chip/stm32/usb.c b/chip/stm32/usb.c
index 1dfb24e0ff..d4ad8e48ea 100644
--- a/chip/stm32/usb.c
+++ b/chip/stm32/usb.c
@@ -74,12 +74,19 @@ static usb_uint ep0_buf_tx[USB_MAX_PACKET_SIZE / 2] __usb_ram;
 static usb_uint ep0_buf_rx[USB_MAX_PACKET_SIZE / 2] __usb_ram;
 
 static int set_addr;
+/* remaining size of descriptor data to transfer */
+static int desc_left;
+/* pointer to descriptor data if any */
+static const uint8_t *desc_ptr;
 
 /* Requests on the control endpoint (aka EP0) */
 static void ep0_rx(void)
 {
 	uint16_t req = ep0_buf_rx[0]; /* bRequestType | bRequest */
 
+	/* reset any incomplete descriptor transfer */
+	desc_ptr = NULL;
+
 	/* interface specific requests */
 	if ((req & USB_RECIP_MASK) == USB_RECIP_INTERFACE) {
 		uint8_t iface = ep0_buf_rx[2] & 0xff;
@@ -92,26 +99,17 @@ static void ep0_rx(void)
 	if (req == (USB_DIR_IN | (USB_REQ_GET_DESCRIPTOR << 8))) {
 		uint8_t type = ep0_buf_rx[1] >> 8;
 		uint8_t idx = ep0_buf_rx[1] & 0xff;
-		const uint8_t *str_desc;
+		const uint8_t *desc;
+		int len;
 
 		switch (type) {
 		case USB_DT_DEVICE: /* Setup : Get device descriptor */
-			memcpy_usbram(ep0_buf_tx, (void *)&dev_desc,
-					 sizeof(dev_desc));
-			btable_ep[0].tx_count = MIN(ep0_buf_rx[3],
-					 sizeof(dev_desc));
-			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
-				  EP_STATUS_OUT /*null OUT transaction */);
+			desc = (void *)&dev_desc;
+			len = sizeof(dev_desc);
 			break;
 		case USB_DT_CONFIGURATION: /* Setup : Get configuration desc */
-			memcpy_usbram(ep0_buf_tx, __usb_desc,
-					 USB_DESC_SIZE);
-			/* set the real descriptor size */
-			ep0_buf_tx[1] = USB_DESC_SIZE;
-			btable_ep[0].tx_count = MIN(ep0_buf_rx[3],
-					 USB_DESC_SIZE);
-			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
-				  EP_STATUS_OUT /*null OUT transaction */);
+			desc = __usb_desc;
+			len = USB_DESC_SIZE;
 			break;
 #ifdef CONFIG_USB_BOS
 		case USB_DT_BOS: /* Setup : Get BOS descriptor */
@@ -120,26 +118,38 @@ static void ep0_rx(void)
 			break;
 #endif
 		case USB_DT_STRING: /* Setup : Get string descriptor */
-			if (idx >= USB_STR_COUNT) {
+			if (idx >= USB_STR_COUNT)
 				/* The string does not exist : STALL */
-				STM32_TOGGLE_EP(0, EP_TX_RX_MASK,
-					  EP_RX_VALID | EP_TX_STALL, 0);
-				return; /* don't remove the STALL */
-			}
-			str_desc = usb_strings[idx];
-			memcpy_usbram(ep0_buf_tx, str_desc, str_desc[0]);
-			btable_ep[0].tx_count = MIN(ep0_buf_rx[3], str_desc[0]);
-			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
-				  EP_STATUS_OUT /*null OUT transaction */);
+				goto unknown_req;
+
+			desc = usb_strings[idx];
+			len = desc[0];
 			break;
 		case USB_DT_DEVICE_QUALIFIER: /* Get device qualifier desc */
 			/* Not high speed : STALL next IN used as handshake */
-			STM32_TOGGLE_EP(0, EP_TX_RX_MASK,
-					EP_RX_VALID | EP_TX_STALL, 0);
-			break;
+			goto unknown_req;
 		default: /* unhandled descriptor */
 			goto unknown_req;
 		}
+		/* do not send more than what the host asked for */
+		len = MIN(ep0_buf_rx[3], len);
+		/*
+		 * if we cannot transmit everything at once,
+		 * keep the remainder for the next IN packet
+		 */
+		if (len >= USB_MAX_PACKET_SIZE) {
+			desc_left = len - USB_MAX_PACKET_SIZE;
+			desc_ptr = desc + USB_MAX_PACKET_SIZE;
+			len = USB_MAX_PACKET_SIZE;
+		}
+		memcpy_usbram(ep0_buf_tx, desc, len);
+		if (type == USB_DT_CONFIGURATION)
+			/* set the real descriptor size */
+			ep0_buf_tx[1] = USB_DESC_SIZE;
+		btable_ep[0].tx_count = len;
+		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
+				desc_left ? 0 : EP_STATUS_OUT);
+		/* send the null OUT transaction if the transfer is complete */
 	} else if (req == (USB_DIR_IN | (USB_REQ_GET_STATUS << 8))) {
 		uint16_t zero = 0;
 		/* Get status */
@@ -182,7 +192,18 @@ static void ep0_tx(void)
 		set_addr = 0;
 		CPRINTF("SETAD %02x\n", STM32_USB_DADDR);
 	}
-
+	if (desc_ptr) {
+		/* we have an on-going descriptor transfer */
+		int len = MIN(desc_left, USB_MAX_PACKET_SIZE);
+		memcpy_usbram(ep0_buf_tx, desc_ptr, len);
+		btable_ep[0].tx_count = len;
+		desc_left -= len;
+		desc_ptr += len;
+		STM32_TOGGLE_EP(0, EP_TX_MASK, EP_TX_VALID,
+				desc_left ? 0 : EP_STATUS_OUT);
+		/* send the null OUT transaction if the transfer is complete */
+		return;
+	}
 	STM32_TOGGLE_EP(0, EP_TX_MASK, EP_TX_VALID, 0);
 }