hammer: Make keyboard work at firmware screen

First, libpayload expects the keyboard interface index to be 0.

Then, hid_iface_request needs to reply to USB_HID_DT_HID request
with the content of struct usb_hid_descriptor. With current code,
the variable name is generated (and therefore hard to guess), so
we create a new set of macros so that we can use a specific
variable name.

Also, add support for HID Get_Protocol and Set_Protocol, as they
are compulsory for devices supporting boot protocol, even though
those are mostly no-op for now.

Finally, add a note regarding USB HID keyboard boot protocol, to
make sure that we do not accidentally change the report format.

BRANCH=none
BUG=b:36538963
TEST=Keyboard works in FW screen, both trackpad and keyboard
     still work when AP has booted.
TEST=hammer/staff can still be updated (both RO from RW, and RW
     from RO)

Change-Id: Ibea4888385909c9ce3b430464e5805c039d4b9ed
Reviewed-on: https://chromium-review.googlesource.com/505796
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

4 files changed, 85 insertions, 25 deletions

diff --git a/chip/stm32/usb_hid.c b/chip/stm32/usb_hid.c
index 5561c8afad..4a89d9573c 100644
--- a/chip/stm32/usb_hid.c
+++ b/chip/stm32/usb_hid.c
@@ -17,6 +17,7 @@
 #include "usb_descriptor.h"
 #include "usb_hw.h"
 #include "usb_hid.h"
+#include "usb_hid_hw.h"
 
 /* Console output macro */
 #define CPRINTF(format, args...) cprintf(CC_USB, format, ## args)
@@ -49,7 +50,8 @@ static int report_left;
 static const uint8_t *report_ptr;
 
 int hid_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx,
-		      const uint8_t *report_desc, int report_size)
+		      const uint8_t *report_desc, int report_size,
+		      const struct usb_hid_descriptor *hid_desc)
 {
 	if (!ep0_buf_rx) {
 		/*
@@ -68,26 +70,35 @@ int hid_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx,
 		STM32_TOGGLE_EP(0, EP_TX_MASK, EP_TX_VALID,
 				report_left ? 0 : EP_STATUS_OUT);
 		return report_left ? 1 : 0;
-	} else if ((ep0_buf_rx[0] == (USB_DIR_IN | USB_RECIP_INTERFACE |
-			      (USB_REQ_GET_DESCRIPTOR << 8))) &&
-			      (ep0_buf_rx[1] == (USB_HID_DT_REPORT << 8))) {
-		/* Setup : HID specific : Get Report descriptor */
-		report_size = MIN(ep0_buf_rx[3], report_size);
+	} else if (ep0_buf_rx[0] == (USB_DIR_IN | USB_RECIP_INTERFACE |
+					(USB_REQ_GET_DESCRIPTOR << 8))) {
+		if (ep0_buf_rx[1] == (USB_HID_DT_REPORT << 8)) {
+			/* Setup : HID specific : Get Report descriptor */
+			report_size = MIN(ep0_buf_rx[3], report_size);
 
-		if (report_size > USB_MAX_PACKET_SIZE) {
-			/* Report descriptor does not fit in one packet. */
-			report_left = report_size - USB_MAX_PACKET_SIZE;
-			report_ptr = report_desc + USB_MAX_PACKET_SIZE;
-			report_size = USB_MAX_PACKET_SIZE;
-		} else {
-			report_left = 0;
+			if (report_size > USB_MAX_PACKET_SIZE) {
+				/* Report descriptor doesn't fit in 1 packet. */
+				report_left = report_size - USB_MAX_PACKET_SIZE;
+				report_ptr = report_desc + USB_MAX_PACKET_SIZE;
+				report_size = USB_MAX_PACKET_SIZE;
+			} else {
+				report_left = 0;
+			}
+			memcpy_to_usbram((void *) usb_sram_addr(ep0_buf_tx),
+					report_desc, report_size);
+			btable_ep[0].tx_count = report_size;
+			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
+					report_left ? 0 : EP_STATUS_OUT);
+			return report_left ? 1 : 0;
+		} else if (ep0_buf_rx[1] == (USB_HID_DT_HID << 8)) {
+			/* Setup : HID specific : Get HID descriptor */
+			memcpy_to_usbram((void *) usb_sram_addr(ep0_buf_tx),
+					hid_desc, sizeof(*hid_desc));
+			btable_ep[0].tx_count = sizeof(*hid_desc);
+			STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
+					EP_STATUS_OUT);
+			return 0;
 		}
-		memcpy_to_usbram((void *) usb_sram_addr(ep0_buf_tx),
-				 report_desc, report_size);
-		btable_ep[0].tx_count = report_size;
-		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID,
-				report_left ? 0 : EP_STATUS_OUT);
-		return report_left ? 1 : 0;
 	}
 
 	return -1;
diff --git a/chip/stm32/usb_hid_hw.h b/chip/stm32/usb_hid_hw.h
index 083bfbfeaa..6e53559bd0 100644
--- a/chip/stm32/usb_hid_hw.h
+++ b/chip/stm32/usb_hid_hw.h
@@ -12,6 +12,7 @@
 void hid_tx(int ep);
 void hid_reset(int ep, usb_uint *hid_ep_buf, int len);
 int hid_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx,
-		      const uint8_t *report_desc, int report_size);
+		      const uint8_t *report_desc, int report_size,
+		      const struct usb_hid_descriptor *hid_desc);
 
 #endif
diff --git a/chip/stm32/usb_hid_keyboard.c b/chip/stm32/usb_hid_keyboard.c
index da3c215050..4147fcad1c 100644
--- a/chip/stm32/usb_hid_keyboard.c
+++ b/chip/stm32/usb_hid_keyboard.c
@@ -26,6 +26,22 @@
 /* Console output macro */
 #define CPRINTF(format, args...) cprintf(CC_USB, format, ## args)
 
+enum hid_protocol {
+	HID_BOOT_PROTOCOL = 0,
+	HID_REPORT_PROTOCOL = 1,
+	HID_PROTOCOL_COUNT = 2,
+};
+
+/* Current protocol, behaviour is identical in both modes. */
+static enum hid_protocol protocol = HID_REPORT_PROTOCOL;
+
+/*
+ * Note: This report format cannot be changed without breaking HID Boot protocol
+ * compatibility (see HID 1.11 "Appendix B: Boot Interface Descriptors").
+ *
+ * If this needs to be extended, we need to use this report in boot protocol
+ * mode, and an alternate one in report protocol mode.
+ */
 struct __attribute__((__packed__)) usb_hid_keyboard_report {
 	uint8_t modifiers; /* bitmap of modifiers 224-231 */
 	uint8_t reserved; /* 0x0 */
@@ -115,7 +131,9 @@ static const uint8_t report_desc[] = {
 	0xC0        /* End Collection */
 };
 
-const struct usb_hid_descriptor USB_CUSTOM_DESC(USB_IFACE_HID_KEYBOARD, hid) = {
+/* HID: HID Descriptor */
+const struct usb_hid_descriptor USB_CUSTOM_DESC_VAR(USB_IFACE_HID_KEYBOARD,
+						hid, hid_desc_kb) = {
 	.bLength = 9,
 	.bDescriptorType = USB_HID_DT_HID,
 	.bcdHID = 0x0100,
@@ -199,8 +217,36 @@ USB_DECLARE_EP(USB_EP_HID_KEYBOARD, hid_keyboard_tx, hid_keyboard_tx,
 static int hid_keyboard_iface_request(usb_uint *ep0_buf_rx,
 				      usb_uint *ep0_buf_tx)
 {
-	return hid_iface_request(ep0_buf_rx, ep0_buf_tx,
-				 report_desc, sizeof(report_desc));
+	int ret = hid_iface_request(ep0_buf_rx, ep0_buf_tx,
+				    report_desc, sizeof(report_desc),
+				    &hid_desc_kb);
+	if (ret >= 0)
+		return ret;
+
+	if (ep0_buf_rx[0] == (USB_DIR_OUT | USB_TYPE_CLASS |
+		       USB_RECIP_INTERFACE | (USB_HID_REQ_SET_PROTOCOL << 8))) {
+		uint16_t value = ep0_buf_rx[1];
+
+		if (value >= HID_PROTOCOL_COUNT)
+			return -1;
+
+		protocol = value;
+
+		btable_ep[0].tx_count = 0;
+		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, 0);
+		return 0;
+	} else if (ep0_buf_rx[0] == (USB_DIR_IN | USB_TYPE_CLASS |
+		       USB_RECIP_INTERFACE | (USB_HID_REQ_GET_PROTOCOL << 8))) {
+		uint8_t value = protocol;
+
+		memcpy_to_usbram((void *) usb_sram_addr(ep0_buf_tx),
+				 &value, sizeof(value));
+		btable_ep[0].tx_count = 1;
+		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_TX_RX_VALID, 0);
+		return 0;
+	}
+
+	return -1;
 }
 USB_DECLARE_IFACE(USB_IFACE_HID_KEYBOARD, hid_keyboard_iface_request)
 
diff --git a/chip/stm32/usb_hid_touchpad.c b/chip/stm32/usb_hid_touchpad.c
index 8f2d2c4dad..686abdcda3 100644
--- a/chip/stm32/usb_hid_touchpad.c
+++ b/chip/stm32/usb_hid_touchpad.c
@@ -250,7 +250,8 @@ static const uint8_t report_desc[] = {
 	0xC0,              /* End Collection */
 };
 
-const struct usb_hid_descriptor USB_CUSTOM_DESC(USB_IFACE_HID_TOUCHPAD, hid) = {
+const struct usb_hid_descriptor USB_CUSTOM_DESC_VAR(USB_IFACE_HID_TOUCHPAD,
+						hid, hid_desc_tp) = {
 	.bLength = 9,
 	.bDescriptorType = USB_HID_DT_HID,
 	.bcdHID = 0x0100,
@@ -309,6 +310,7 @@ static int hid_touchpad_iface_request(usb_uint *ep0_buf_rx,
 				      usb_uint *ep0_buf_tx)
 {
 	return hid_iface_request(ep0_buf_rx, ep0_buf_tx,
-				 report_desc, sizeof(report_desc));
+				 report_desc, sizeof(report_desc),
+				 &hid_desc_tp);
 }
 USB_DECLARE_IFACE(USB_IFACE_HID_TOUCHPAD, hid_touchpad_iface_request)