[PATCH v6 13/14] usb: typec: tcpci: Implement Auto discharge disconnect callbacks

Badhri Jagan Sridharan
2020-09-01T03:00:10Z

Implement callbacks for enabling/disabling
POWER_CONTROL.AutoDischargeDisconnect.

TCPCI spec allows TCPC hardware to autonomously discharge the vbus
capacitance upon disconnect. The expectation is that the TCPM enables
AutoDischargeDisconnect while entering SNK/SRC_ATTACHED states. Hardware
then automously discharges vbus when the vbus falls below a certain
threshold i.e. VBUS_SINK_DISCONNECT_THRESHOLD.

Apart from enabling the vbus discharge circuit, AutoDischargeDisconnect
is also used a flag to move TCPCI based TCPC implementations into
Attached.Snk/Attached.Src state as mentioned in
Figure 4-15. TCPC State Diagram before a Connection of the
USB Type-C Port Controller Interface Specification.
In such TCPC implementations, setting AutoDischargeDisconnect would
prevent TCPC into entering "Connection_Invalid" state as well.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
Changes since v1:
- Changing patch version to v6 to fix version number confusion.
---
drivers/usb/typec/tcpm/tcpci.c | 33 +++++++++++++++++++++++++++++++++
drivers/usb/typec/tcpm/tcpci.h | 22 ++++++++++++++++++++--
2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index f9f0af64da5f..4ca64e8c8fe8 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -268,6 +268,33 @@ static int tcpci_set_vconn(struct tcpc_dev *tcpc, bool enable)
enable ? TCPC_POWER_CTRL_VCONN_ENABLE : 0);
}

+static int tcpci_enable_auto_vbus_discharge(struct tcpc_dev *dev, bool enable)
+{
+ struct tcpci *tcpci = tcpc_to_tcpci(dev);
+ int ret;
+
+ ret = regmap_update_bits(tcpci->regmap, TCPC_POWER_CTRL, TCPC_POWER_CTRL_AUTO_DISCHARGE,
+ enable ? TCPC_POWER_CTRL_AUTO_DISCHARGE : 0);
+ return ret;
+}
+
+static int tcpci_set_auto_vbus_discharge_threshold(struct tcpc_dev *dev, enum typec_role port_role,
+ enum typec_pwr_opmode mode, bool pps_active,
+ u32 requested_vbus_voltage)
+{
+ struct tcpci *tcpci = tcpc_to_tcpci(dev);
+ int (*set_auto_vbus_threshold)(struct tcpci *tcpci, struct tcpci_data *data,
+ enum typec_role port_role, enum typec_pwr_opmode mode,
+ bool pps_active, u32 requested_vbus_voltage);
+
+ set_auto_vbus_threshold = tcpci->data->set_auto_vbus_discharge_threshold;
+ if (set_auto_vbus_threshold)
+ return set_auto_vbus_threshold(tcpci, tcpci->data, port_role, mode, pps_active,
+ requested_vbus_voltage);
+
+ return 0;
+}
+
static int tcpci_enable_frs(struct tcpc_dev *dev, bool enable)
{
struct tcpci *tcpci = tcpc_to_tcpci(dev);
@@ -629,6 +656,12 @@ struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data)
tcpci->tcpc.set_bist_data = tcpci_set_bist_data;
tcpci->tcpc.enable_frs = tcpci_enable_frs;

+ if (tcpci->data->auto_discharge_disconnect) {
+ tcpci->tcpc.enable_auto_vbus_discharge = tcpci_enable_auto_vbus_discharge;
+ tcpci->tcpc.set_auto_vbus_discharge_threshold =
+ tcpci_set_auto_vbus_discharge_threshold;
+ }
+
err = tcpci_parse_config(tcpci);
if (err < 0)
return ERR_PTR(err);
diff --git a/drivers/usb/typec/tcpm/tcpci.h b/drivers/usb/typec/tcpm/tcpci.h
index 5ef07a56d67a..6a0aea34e544 100644
--- a/drivers/usb/typec/tcpm/tcpci.h
+++ b/drivers/usb/typec/tcpm/tcpci.h
@@ -8,6 +8,8 @@
#ifndef __LINUX_USB_TCPCI_H
#define __LINUX_USB_TCPCI_H

+#include <linux/usb/typec.h>
+
#define TCPC_VENDOR_ID 0x0
#define TCPC_PRODUCT_ID 0x2
#define TCPC_BCD_DEV 0x4
@@ -67,6 +69,7 @@

#define TCPC_POWER_CTRL 0x1c
#define TCPC_POWER_CTRL_VCONN_ENABLE BIT(0)
+#define TCPC_POWER_CTRL_AUTO_DISCHARGE BIT(4)
#define TCPC_FAST_ROLE_SWAP_EN BIT(7)

#define TCPC_CC_STATUS 0x1d
@@ -133,6 +136,8 @@

#define TCPC_VBUS_VOLTAGE 0x70
#define TCPC_VBUS_SINK_DISCONNECT_THRESH 0x72
+#define TCPC_VBUS_SINK_DISCONNECT_THRESH_LSB 25
+#define TCPC_VBUS_SINK_DISCONNECT_THRESH_MAX 1023
#define TCPC_VBUS_STOP_DISCHARGE_THRESH 0x74
#define TCPC_VBUS_VOLTAGE_ALARM_HI_CFG 0x76
#define TCPC_VBUS_VOLTAGE_ALARM_LO_CFG 0x78
@@ -140,20 +145,33 @@
/* I2C_WRITE_BYTE_COUNT + 1 when TX_BUF_BYTE_x is only accessible I2C_WRITE_BYTE_COUNT */
#define TCPC_TRANSMIT_BUFFER_MAX_LEN 31

+struct tcpci;
+
/*
- * @TX_BUF_BYTE_x_hidden
+ * @TX_BUF_BYTE_x_hidden:
* optional; Set when TX_BUF_BYTE_x can only be accessed through I2C_WRITE_BYTE_COUNT.
+ * @auto_discharge_disconnect:
+ * Optional; Enables TCPC to autonously discharge vbus on disconnect.
+ * @set_auto_vbus_discharge_threshold:
+ * Mandatory when @auto_discharge_disconnect is sets. Allows
+ * programming the voltage threshold of vbus below which TCPC
+ * enables the vbus discharge circuit.
*/
-struct tcpci;
struct tcpci_data {
struct regmap *regmap;
unsigned char TX_BUF_BYTE_x_hidden:1;
+ unsigned char auto_discharge_disconnect:1;
+
int (*init)(struct tcpci *tcpci, struct tcpci_data *data);
int (*set_vconn)(struct tcpci *tcpci, struct tcpci_data *data,
bool enable);
int (*start_drp_toggling)(struct tcpci *tcpci, struct tcpci_data *data,
enum typec_cc_status cc);
int (*set_vbus)(struct tcpci *tcpci, struct tcpci_data *data, bool source, bool sink);
+ int (*set_auto_vbus_discharge_threshold)(struct tcpci *tcpci, struct tcpci_data *data,
+ enum typec_role port_role,
+ enum typec_pwr_opmode mode, bool pps_active,
+ u32 requested_vbus_voltage);
};

struct tcpci *tcpci_register_port(struct device *dev, struct tcpci_data *data);
--
2.28.0.402.g5ffc5be6b7-goog