usb pd: Adding PPC vbus discharge path

Boards with a PPC will use the PPC to discharge the VBUS line instead
of the TCPC or GPIO discharge path.

BRANCH=none
BUG=b:72179253
TEST=Fall time after device removal on grunt within spec now

Change-Id: I822923a1cedb32a20efc3610cce4437ade3387f0
Signed-off-by: Jett Rink <jettrink@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/886563
Reviewed-by: Edward Hill <ecgh@chromium.org>

6 files changed, 69 insertions, 9 deletions

diff --git a/common/usb_pd_policy.c b/common/usb_pd_policy.c
index 936ad6980f..01784e87ad 100644
--- a/common/usb_pd_policy.c
+++ b/common/usb_pd_policy.c
@@ -21,6 +21,7 @@
 #include "util.h"
 #include "usb_api.h"
 #include "usb_pd.h"
+#include "usbc_ppc.h"
 #include "version.h"
 
 #ifdef CONFIG_COMMON_RUNTIME
@@ -1035,6 +1036,8 @@ void pd_set_vbus_discharge(int port, int enable)
 #endif /* CONFIG_USB_PD_PORT_COUNT */
 #elif defined(CONFIG_USB_PD_DISCHARGE_TCPC)
 	tcpc_discharge_vbus(port, enable);
+#elif defined(CONFIG_USB_PD_DISCHARGE_PPC)
+	ppc_discharge_vbus(port, enable);
 #else
 #error "PD discharge implementation not defined"
 #endif
diff --git a/common/usbc_ppc.c b/common/usbc_ppc.c
index 3c6d437152..34cfbabf50 100644
--- a/common/usbc_ppc.c
+++ b/common/usbc_ppc.c
@@ -50,6 +50,14 @@ int ppc_set_vbus_source_current_limit(int port, enum tcpc_rp_value rp)
 	return ppc_chips[port].drv->set_vbus_source_current_limit(port, rp);
 }
 
+int ppc_discharge_vbus(int port, int enable)
+{
+	if ((port < 0) || (port >= ppc_cnt))
+		return EC_ERROR_INVAL;
+
+	return ppc_chips[port].drv->discharge_vbus(port, enable);
+}
+
 int ppc_vbus_sink_enable(int port, int enable)
 {
 	if ((port < 0) || (port >= ppc_cnt))
diff --git a/driver/ppc/sn5s330.c b/driver/ppc/sn5s330.c
index 1f4d20eb76..d21dba0f66 100644
--- a/driver/ppc/sn5s330.c
+++ b/driver/ppc/sn5s330.c
@@ -480,6 +480,29 @@ static int sn5s330_set_vbus_source_current_limit(int port,
 	return status;
 }
 
+static int sn5s330_discharge_vbus(int port, int enable)
+{
+	int regval;
+	int status;
+
+	status = get_func_set3(port, &regval);
+	if (status)
+		return status;
+
+	if (enable)
+		regval |= SN5S330_VBUS_DISCH_EN;
+	else
+		regval &= ~SN5S330_VBUS_DISCH_EN;
+
+	status = write_reg(port, SN5S330_FUNC_SET3, regval);
+	if (status) {
+		CPRINTS("Failed to %s vbus", enable ? "enable" : "disable");
+		return status;
+	}
+
+	return EC_SUCCESS;
+}
+
 static int sn5s330_vbus_sink_enable(int port, int enable)
 {
 	return sn5s330_pp_fet_enable(port, SN5S330_PP2, !!enable);
@@ -540,4 +563,5 @@ const struct ppc_drv sn5s330_drv = {
 	.is_vbus_present = &sn5s330_is_vbus_present,
 #endif /* defined(CONFIG_USB_PD_VBUS_DETECT_PPC) */
 	.set_vbus_source_current_limit = &sn5s330_set_vbus_source_current_limit,
+	.discharge_vbus = &sn5s330_discharge_vbus,
 };
diff --git a/driver/ppc/sn5s330.h b/driver/ppc/sn5s330.h
index d3d3248a80..18f1929c0f 100644
--- a/driver/ppc/sn5s330.h
+++ b/driver/ppc/sn5s330.h
@@ -91,6 +91,7 @@ enum sn5s330_pp_idx {
 /* FUNC_SET_3 */
 #define SN5S330_PP1_EN (1 << 0)
 #define SN5S330_PP2_EN (1 << 1)
+#define SN5S330_VBUS_DISCH_EN (1 << 2)
 #define SN5S330_SET_RCP_MODE_PP1 (1 << 5)
 #define SN5S330_SET_RCP_MODE_PP2 (1 << 6)
 
diff --git a/include/config.h b/include/config.h
index 5b2697ae93..c6a57bcf13 100644
--- a/include/config.h
+++ b/include/config.h
@@ -2634,22 +2634,20 @@
 /*
  * Define if this board can enable VBUS discharge (eg. through a GPIO-controlled
  * discharge circuit, or through port controller registers) to discharge VBUS
- * rapidly on disconnect.
+ * rapidly on disconnect. Will be defined automatically when one of the below
+ * options is defined.
  */
 #undef CONFIG_USB_PD_DISCHARGE
 
-/*
- * Define (along with CONFIG_USB_PD_DISCHARGE) if discharge circuit is
- * EC GPIO-controlled.
- */
+/* Define if discharge circuit is EC GPIO-controlled. */
 #undef CONFIG_USB_PD_DISCHARGE_GPIO
 
-/*
- * Define (along with CONFIG_USB_PD_DISCHARGE) if discharge circuit is
- * using PD discharge registers.
- */
+/* Define if discharge circuit is using PD discharge registers on TCPC. */
 #undef CONFIG_USB_PD_DISCHARGE_TCPC
 
+/* Define if discharge circuit is using PD discharge registers on PPC. */
+#undef CONFIG_USB_PD_DISCHARGE_PPC
+
 /* Define if this board can act as a dual-role PD port (source and sink) */
 #undef CONFIG_USB_PD_DUAL_ROLE
 
@@ -3274,6 +3272,14 @@
 #endif /* CONFIG_EC_EC_COMM_BATTERY */
 
 /*****************************************************************************/
+/* Define derived USB PD Discharge common path */
+#if defined(CONFIG_USB_PD_DISCHARGE_GPIO) || \
+	defined(CONFIG_USB_PD_DISCHARGE_TCPC) || \
+	defined(CONFIG_USB_PD_DISCHARGE_PPC)
+#define CONFIG_USB_PD_DISCHARGE
+#endif
+
+/*****************************************************************************/
 /*
  * Handle task-dependent configs.
  *
diff --git a/include/usbc_ppc.h b/include/usbc_ppc.h
index c005540e99..4fbb913a11 100644
--- a/include/usbc_ppc.h
+++ b/include/usbc_ppc.h
@@ -57,6 +57,15 @@ struct ppc_drv {
 	 */
 	int (*set_vbus_source_current_limit)(int port, enum tcpc_rp_value rp);
 
+	/**
+	 * Discharge PD VBUS on src/sink disconnect & power role swap
+	 *
+	 * @param port: The Type-C port number.
+	 * @param enable: 1 -> discharge vbus, 0 -> stop discharging vbus
+	 * @return EC_SUCCESS on success, error otherwise.
+	 */
+	int (*discharge_vbus)(int port, int enable);
+
 #ifdef CONFIG_CMD_PPC_DUMP
 	/**
 	 * Perform a register dump of the PPC.
@@ -131,6 +140,15 @@ int ppc_is_sourcing_vbus(int port);
 int ppc_set_vbus_source_current_limit(int port, enum tcpc_rp_value rp);
 
 /**
+ * Discharge PD VBUS on src/sink disconnect & power role swap
+ *
+ * @param port: The Type-C port number.
+ * @param enable: 1 -> discharge vbus, 0 -> stop discharging vbus
+ * @return EC_SUCCESS on success, error otherwise.
+ */
+int ppc_discharge_vbus(int port, int enable);
+
+/**
  * Turn on/off the charge path FET, such that current flows into the
  * system.
  *