cheza: Mux the 1st-plugged UFP port which is not a charger

There are 2 USB-C ports. A user may plug a USB-C to USB-A male
cable to one of the ports; then EC should mux the port from USB
hub to AP's primary USB controller, which is configured to do USB
peripheral mode only.

The policy is to mux the first-plugged UFP port to AP, with the
following exception:
* If the partner port does PD and it advertises the USB communications
  capable bit unset in the fixed-supply PDO, we believe the partner
  port is a pure charger.
* If the BC1.2 chip detects the partner is not a SDP or CDP , we
  believe the partner port is not a workstation.

Check the design doc at:
  http://go/cheza-hs-mux

BRANCH=none
BUG=b:74395451, b:110803836
TEST=Check the following scenario:
* Plug charger w/ PD to P0, plug C-to-A to P1, check P1 mux to AP.
* Plug charger through hub to P0, plug C-to-A to P1, check P1 mux to AP.
* Continue the above case, boot into kernel and check USB peripheral mode.
* Plug BC1.2 charger to P0, plug C-to-A to P1, check P1 mux to AP.
* Plug charger w/o PD to P0, plug C-to-A to P1, check P0 mux to AP.
* Swap P0 and P1 for the above cases and check the results.

Change-Id: I4034fa66c0b27cc48d0959bb3f1750690ad5e3f7
Signed-off-by: Wai-Hong Tam <waihong@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1105404
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

6 files changed, 55 insertions, 4 deletions

diff --git a/board/cheza/gpio.inc b/board/cheza/gpio.inc
index c721f94b73..72cd70ab0f 100644
--- a/board/cheza/gpio.inc
+++ b/board/cheza/gpio.inc
@@ -102,8 +102,6 @@ GPIO(CHG_LED_W_C1,          PIN(C, 0), GPIO_OUT_LOW)   /* EC_CHG_LED_W_C1 */
  *      +------- C1_MUX:D2
  *          | |
  * AP --- USB_HUB
- *
- * TODO(waihong): Support auto-detection and switching.
  */
 /* Switch both port-0 and port-1 to the hub, which matches the SS path. */
 GPIO(USB_C0_HS_MUX_OE_L,    PIN(A, 4), GPIO_OUT_LOW)
diff --git a/board/cheza/usb_pd_policy.c b/board/cheza/usb_pd_policy.c
index 5f5e707819..bbc44a746e 100644
--- a/board/cheza/usb_pd_policy.c
+++ b/board/cheza/usb_pd_policy.c
@@ -6,6 +6,7 @@
 #include "charge_manager.h"
 #include "console.h"
 #include "gpio.h"
+#include "pi3usb9281.h"
 #include "system.h"
 #include "usb_mux.h"
 #include "usbc_ppc.h"
@@ -93,7 +94,38 @@ int pd_check_vconn_swap(int port)
 
 void pd_execute_data_swap(int port, int data_role)
 {
-	/* Do nothing */
+	int enable = (data_role == PD_ROLE_UFP);
+	int type;
+
+	/*
+	 * Exclude the PD charger, in which the "USB Communications Capable"
+	 * bit is unset in the Fixed Supply PDO.
+	 */
+	if (pd_capable(port))
+		enable = enable && pd_get_partner_usb_comm_capable(port);
+
+	/*
+	 * The hub behind the BC1.2 chip may advertise a BC1.2 type. So
+	 * disconnect the switch when getting the charger type to ensure
+	 * the detected type is from external.
+	 */
+	usb_charger_set_switches(port, USB_SWITCH_DISCONNECT);
+	type = pi3usb9281_get_device_type(port);
+	usb_charger_set_switches(port, USB_SWITCH_RESTORE);
+
+	/* Exclude the BC1.2 charger, which is not detected as CDP or SDP. */
+	enable = enable && (type & (PI3USB9281_TYPE_CDP | PI3USB9281_TYPE_SDP));
+
+	/* Only mux one port to AP. If already muxed, return. */
+	if (enable && (!gpio_get_level(GPIO_USB_C0_HS_MUX_SEL) ||
+		       gpio_get_level(GPIO_USB_C1_HS_MUX_SEL)))
+		return;
+
+	/* Port-0 and port-1 have different polarities. */
+	if (port == 0)
+		gpio_set_level(GPIO_USB_C0_HS_MUX_SEL, enable ? 0 : 1);
+	else if (port == 1)
+		gpio_set_level(GPIO_USB_C1_HS_MUX_SEL, enable ? 1 : 0);
 }
 
 int pd_is_valid_input_voltage(int mv)
diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 7a8634e174..6abb24ed51 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -336,6 +336,15 @@ int pd_capable(int port)
 	return pd[port].flags & PD_FLAGS_PREVIOUS_PD_CONN;
 }
 
+/*
+ * Return true if partner port is capable of communication over USB data
+ * lines.
+ */
+int pd_get_partner_usb_comm_capable(int port)
+{
+	return pd[port].flags & PD_FLAGS_PARTNER_USB_COMM;
+}
+
 #ifdef CONFIG_USB_PD_DUAL_ROLE
 void pd_vbus_low(int port)
 {
diff --git a/driver/bc12/pi3usb9281.c b/driver/bc12/pi3usb9281.c
index f1bd3ce8d4..06a1efba61 100644
--- a/driver/bc12/pi3usb9281.c
+++ b/driver/bc12/pi3usb9281.c
@@ -183,7 +183,7 @@ static int pi3usb9281_get_interrupts(int port)
 	return pi3usb9281_read(port, PI3USB9281_REG_INT);
 }
 
-static int pi3usb9281_get_device_type(int port)
+int pi3usb9281_get_device_type(int port)
 {
 	return pi3usb9281_read(port, PI3USB9281_REG_DEV_TYPE) & 0x77;
 }
diff --git a/driver/pi3usb9281.h b/driver/pi3usb9281.h
index fe19f0e977..fd4375b9b1 100644
--- a/driver/pi3usb9281.h
+++ b/driver/pi3usb9281.h
@@ -74,4 +74,7 @@ extern struct pi3usb9281_config pi3usb9281_chips[];
 /* Enable interrupts. */
 int pi3usb9281_enable_interrupts(int port);
 
+/* Get the device type */
+int pi3usb9281_get_device_type(int port);
+
 #endif /* __CROS_EC_PI3USB9281_H */
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 1927add067..f451206b4b 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -1832,6 +1832,15 @@ int pd_ts_dts_plugged(int port);
  */
 int pd_capable(int port);
 
+
+/**
+ * Return true if partner port is capable of communication over USB data
+ * lines.
+ *
+ * @param port USB-C port number
+ */
+int pd_get_partner_usb_comm_capable(int port);
+
 /**
  * Return true if vbus is present on the specified port.
  *