stm32: Add the DFU Runtime identifiers

Adds a DFU Runtime identifier and a DFU bootmanager to control the
switch between the DFU and main application region.

The DFU runtime identifier operates on the main application in the RW
region. A DFU host recognizes the interface and can send commands to
switch the firmware into DFU mode.

BRANCH=servo
BUG=b:217955677
TEST=Enabled the DFU configuration on Servo_v4 with CONFIG_DFU_RUNTIME
TEST='sudo dfu-util -l' Verified the dfu-util recognizes the
    DFU runtime device.

Signed-off-by: Brian Nemec <bnemec@chromium.org>
Change-Id: I0e02b7cb35a7c594f169c56a96f965e5d87e3cfb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3441173
Tested-by: Brian Nemec <bnemec@google.com>
Reviewed-by: Sam Hurst <shurst@google.com>
Commit-Queue: Brian Nemec <bnemec@google.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/chip/stm32/usb_dfu_runtime.c b/chip/stm32/usb_dfu_runtime.c
new file mode 100644
index 0000000000..b902f32af2
--- /dev/null
+++ b/chip/stm32/usb_dfu_runtime.c
@@ -0,0 +1,91 @@
+/* Copyright 2022 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "registers.h"
+#include "usb_descriptor.h"
+#include "usb_dfu_runtime.h"
+#include "usb_hw.h"
+
+/* DFU Run-Time Descriptor Set. */
+const struct usb_interface_descriptor USB_IFACE_DESC(USB_IFACE_DFU) = {
+	.bLength = USB_DT_INTERFACE_SIZE,
+	.bDescriptorType = USB_DT_INTERFACE,
+	.bInterfaceNumber = USB_IFACE_DFU,
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 0,
+	.bInterfaceClass = USB_CLASS_APP_SPEC,
+	.bInterfaceSubClass = USB_DFU_RUNTIME_SUBCLASS,
+	.bInterfaceProtocol = USB_DFU_RUNTIME_PROTOCOL,
+	.iInterface = USB_STR_DFU_NAME,
+};
+
+/* DFU Functional Descriptor. */
+const struct usb_runtime_dfu_functional_desc USB_CUSTOM_DESC_VAR(USB_IFACE_DFU,
+						dfu, dfu_func_desc) = {
+	.bLength = USB_DFU_RUNTIME_DESC_SIZE,
+	.bDescriptorType = USB_DFU_RUNTIME_DESC_FUNCTIONAL,
+	.bmAttributes = USB_DFU_RUNTIME_DESC_ATTRS,
+	.wDetachTimeOut = USB_DFU_RUNTIME_DESC_DETACH_TIMEOUT,
+	.wTransferSize = USB_DFU_RUNTIME_DESC_TRANSFER_SIZE,
+	.bcdDFUVersion = USB_DFU_RUNTIME_DESC_DFU_VERSION,
+};
+
+static int dfu_runtime_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx)
+{
+	struct usb_setup_packet packet;
+
+	usb_read_setup_packet(ep0_buf_rx, &packet);
+	btable_ep[0].tx_count = 0;
+	if ((packet.bmRequestType ==
+		(USB_DIR_OUT | USB_TYPE_STANDARD |  USB_RECIP_INTERFACE)) &&
+		(packet.bRequest == USB_REQ_SET_INTERFACE)) {
+		/* ACK the change alternative mode request. */
+
+		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, 0);
+		return 0;
+	} else if ((packet.bmRequestType ==
+			(USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE)) &&
+			(packet.bRequest == USB_DFU_RUNTIME_REQ_DETACH)) {
+		/* Host is requesting a jump from application to DFU mode. */
+
+		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, 0);
+		return 0;
+	} else if (packet.bmRequestType ==
+			(USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE)) {
+		if (packet.bRequest == USB_DFU_RUNTIME_REQ_GET_STATUS) {
+			/* Return the Get Status response. */
+
+			struct usb_runtime_dfu_get_status_resp response = {
+				.bStatus = USB_DFU_RUNTIME_STATUS_OK,
+				.bState = USB_DFU_RUNTIME_STATE_APP_IDLE,
+			};
+
+			memcpy_to_usbram((void *) usb_sram_addr(ep0_buf_tx),
+				&response, sizeof(response));
+			btable_ep[0].tx_count = sizeof(response);
+			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, 0);
+			return 0;
+		}
+		if (packet.bRequest == USB_DFU_RUNTIME_REQ_GET_STATE) {
+			/* Return the Get State response. */
+
+			struct usb_runtime_dfu_get_state_resp response = {
+				.bState = USB_DFU_RUNTIME_STATE_APP_IDLE,
+			};
+
+			memcpy_to_usbram((void *) usb_sram_addr(ep0_buf_tx),
+				&response, sizeof(response));
+			btable_ep[0].tx_count = sizeof(response);
+			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, 0);
+			return 0;
+		}
+	}
+	/* Return a stall response for any unhandled packets. */
+
+	STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_RX_VALID | EP_TX_STALL, 0);
+	return 0;
+}
+
+USB_DECLARE_IFACE(USB_IFACE_DFU, dfu_runtime_request)