update case closed debugging partial mode policy

When a debug accessory is connected to the type-C port while the write
protection is enabled, put the case closed debugging in "partial" mode
rather than "full".

Update the "partial" mode to provide read-only access to the AP and EC
consoles.

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

BRANCH=smaug
BUG=chrome-os-partner:44700
TEST=check the EC console input/output over USB is still working with SuzyQ
on a write-protected system, verify that the console input is disabled.

Change-Id: I5baa03d6e738d06437c45469f46b286e76a755a4
Reviewed-on: https://chromium-review.googlesource.com/297141
Commit-Ready: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>

9 files changed, 36 insertions, 13 deletions

diff --git a/board/ryu/board.c b/board/ryu/board.c
index 49a7e1bf0a..24402d42fc 100644
--- a/board/ryu/board.c
+++ b/board/ryu/board.c
@@ -30,6 +30,7 @@
 #include "queue_policies.h"
 #include "registers.h"
 #include "spi.h"
+#include "system.h"
 #include "task.h"
 #include "usb.h"
 #include "usb_charge.h"
@@ -144,6 +145,9 @@ static void board_init(void)
 	queue_init(&ap_usart_to_usb);
 	queue_init(&ap_usb_to_usart);
 	usart_init(&ap_usart);
+	/* Disable UART input when the Write Protect is enabled */
+	if (system_is_locked())
+		ap_usb.state->rx_disabled = 1;
 
 	/*
 	 * Enable CC lines after all GPIO have been initialized. Note, it is
diff --git a/board/ryu/usb_pd_policy.c b/board/ryu/usb_pd_policy.c
index 14e5828f17..ea709a3b53 100644
--- a/board/ryu/usb_pd_policy.c
+++ b/board/ryu/usb_pd_policy.c
@@ -255,7 +255,8 @@ int pd_custom_vdm(int port, int cnt, uint32_t *payload,
 #endif /* CONFIG_USB_PD_LOGGING */
 #ifdef CONFIG_CASE_CLOSED_DEBUG
 	case VDO_CMD_CCD_EN:
-		ccd_set_mode(CCD_MODE_ENABLED);
+		ccd_set_mode(system_is_locked() ? CCD_MODE_PARTIAL
+						: CCD_MODE_ENABLED);
 		break;
 #endif
 	}
diff --git a/chip/g/usb_console.c b/chip/g/usb_console.c
index 19bcf7d243..d075bdac09 100644
--- a/chip/g/usb_console.c
+++ b/chip/g/usb_console.c
@@ -29,6 +29,7 @@ static int last_tx_ok = 1;
 
 static int is_reset;
 static int is_enabled = 1;
+static int is_readonly;
 
 /* USB-Serial descriptors */
 const struct usb_interface_descriptor USB_IFACE_DESC(USB_IFACE_CONSOLE) =
@@ -76,7 +77,7 @@ static void con_ep_tx(void)
 static void con_ep_rx(void)
 {
 	int i;
-	int rx_size = USB_MAX_PACKET_SIZE
+	int rx_size = is_readonly ? 0 : USB_MAX_PACKET_SIZE
 		    - (ep_out_desc.flags & DOEPDMA_RXBYTES_MASK);
 
 	for (i = 0; i < rx_size; i++) {
@@ -94,7 +95,8 @@ static void con_ep_rx(void)
 	GR_USB_DOEPINT(USB_EP_CONSOLE) = 0xffffffff;
 
 	/* wake-up the console task */
-	console_has_input();
+	if (!is_readonly)
+		console_has_input();
 }
 
 static void ep_reset(void)
@@ -254,7 +256,8 @@ int usb_vprintf(const char *format, va_list args)
 	return ret;
 }
 
-void usb_console_enable(int enabled)
+void usb_console_enable(int enabled, int readonly)
 {
 	is_enabled = enabled;
+	is_readonly = readonly;
 }
diff --git a/chip/stm32/usb-stream.c b/chip/stm32/usb-stream.c
index 256dc829e1..08004dcad4 100644
--- a/chip/stm32/usb-stream.c
+++ b/chip/stm32/usb-stream.c
@@ -56,6 +56,11 @@ static int rx_valid(struct usb_stream_config const *config)
 	return (STM32_USB_EP(config->endpoint) & EP_RX_MASK) == EP_RX_VALID;
 }
 
+static int rx_disabled(struct usb_stream_config const *config)
+{
+	return config->state->rx_disabled;
+}
+
 static void usb_read(struct producer const *producer, size_t count)
 {
 	struct usb_stream_config const *config =
@@ -95,7 +100,7 @@ void usb_stream_deferred(struct usb_stream_config const *config)
 	if (!tx_valid(config) && tx_write(config))
 		STM32_TOGGLE_EP(config->endpoint, EP_TX_MASK, EP_TX_VALID, 0);
 
-	if (!rx_valid(config) && rx_read(config))
+	if (!rx_valid(config) && !rx_disabled(config) && rx_read(config))
 		STM32_TOGGLE_EP(config->endpoint, EP_RX_MASK, EP_RX_VALID, 0);
 }
 
@@ -136,5 +141,5 @@ void usb_stream_reset(struct usb_stream_config const *config)
 	STM32_USB_EP(i) = ((i <<  0) | /* Endpoint Addr*/
 			   (2 <<  4) | /* TX NAK */
 			   (0 <<  9) | /* Bulk EP */
-			   (3 << 12)); /* RX VALID */
+			   (rx_disabled(config) ? EP_RX_NAK : EP_RX_VALID));
 }
diff --git a/chip/stm32/usb-stream.h b/chip/stm32/usb-stream.h
index c99fd3e695..da2d677880 100644
--- a/chip/stm32/usb-stream.h
+++ b/chip/stm32/usb-stream.h
@@ -31,6 +31,10 @@ struct usb_stream_state {
 	 * restart USB reception by marking the RX buffer as VALID.
 	 */
 	int rx_waiting;
+	/*
+	 * Flag indicating that the incoming data on the USB link are discarded.
+	 */
+	int rx_disabled;
 };
 
 /*
diff --git a/chip/stm32/usb_console.c b/chip/stm32/usb_console.c
index 665568a28a..7688d4af29 100644
--- a/chip/stm32/usb_console.c
+++ b/chip/stm32/usb_console.c
@@ -29,6 +29,7 @@ static int last_tx_ok = 1;
 
 static int is_reset;
 static int is_enabled = 1;
+static int is_readonly;
 
 /* USB-Serial descriptors */
 const struct usb_interface_descriptor USB_IFACE_DESC(USB_IFACE_CONSOLE) = {
@@ -100,7 +101,8 @@ static void ep_reset(void)
 	STM32_USB_EP(USB_EP_CONSOLE) = (USB_EP_CONSOLE | /* Endpoint Addr */
 					(2 << 4)       | /* TX NAK        */
 					(0 << 9)       | /* Bulk EP       */
-					(3 << 12));      /* RX VALID      */
+					(is_readonly ? EP_RX_NAK
+						     : EP_RX_VALID));
 
 	is_reset = 1;
 }
@@ -248,7 +250,8 @@ int usb_vprintf(const char *format, va_list args)
 	return ret;
 }
 
-void usb_console_enable(int enabled)
+void usb_console_enable(int enabled, int readonly)
 {
 	is_enabled = enabled;
+	is_readonly = readonly;
 }
diff --git a/common/case_closed_debug.c b/common/case_closed_debug.c
index 3adc563c4f..31477b7554 100644
--- a/common/case_closed_debug.c
+++ b/common/case_closed_debug.c
@@ -41,10 +41,11 @@ void ccd_set_mode(enum ccd_mode new_mode)
 	current_mode = new_mode;
 
 	/*
-	 * Only enable forwarding the local console over USB if we are now in
-	 * the fully enabled mode.
+	 * The forwarding of the local console over USB is read-only
+	*  if we are not in the fully enabled mode.
 	 */
-	usb_console_enable(new_mode == CCD_MODE_ENABLED);
+	usb_console_enable(new_mode != CCD_MODE_DISABLED,
+			   new_mode != CCD_MODE_ENABLED);
 
 #if defined(CONFIG_USB_SPI)
 	usb_spi_enable(&ccd_usb_spi, new_mode == CCD_MODE_ENABLED);
diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 07ce8189dc..11a1f62c9c 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -1590,7 +1590,9 @@ void pd_task(void)
 
 #ifdef CONFIG_CASE_CLOSED_DEBUG
 				if (new_cc_state == PD_CC_DEBUG_ACC) {
-					ccd_set_mode(CCD_MODE_ENABLED);
+					ccd_set_mode(system_is_locked() ?
+						     CCD_MODE_PARTIAL :
+						     CCD_MODE_ENABLED);
 					typec_set_input_current_limit(
 						port, 3000, TYPE_C_VOLTAGE);
 					charge_manager_update_dualrole(
diff --git a/include/usb_console.h b/include/usb_console.h
index d83fc480b0..08cbbf5491 100644
--- a/include/usb_console.h
+++ b/include/usb_console.h
@@ -50,7 +50,7 @@ int usb_getc(void);
  * is not accessible until the USB peripheral is also initialized, which can
  * be delayed.
  */
-void usb_console_enable(int enabled);
+void usb_console_enable(int enabled, int readonly);
 
 #define usb_va_start va_start
 #define usb_va_end va_end