linux-kernel - [PATCH v6 14/14] usb: typec: tcpci_maxim: Implemnent set_auto_vbus_discharge

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Message-Id: <20200901025927.3596190-15-badhri@google.com>
Date:   Mon, 31 Aug 2020 19:59:27 -0700
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Badhri Jagan Sridharan <badhri@...gle.com>
Subject: [PATCH v6 14/14] usb: typec: tcpci_maxim: Implemnent set_auto_vbus_discharge_threshold

Programs VBUS_SINK_DISCONNECT_THRESHOLD based on the power_role,
voltage requested as sink, mode of operation.

The programmed threshold is based on vSinkDisconnect and
vSinkDisconnectPD values.

Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
---
Changes since v1:
- Changing patch version to v6 to fix version number confusion.
---
 drivers/usb/typec/tcpm/tcpci_maxim.c | 48 ++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.c b/drivers/usb/typec/tcpm/tcpci_maxim.c
index 6ba808ad901a..e35bd995c037 100644
--- a/drivers/usb/typec/tcpm/tcpci_maxim.c
+++ b/drivers/usb/typec/tcpm/tcpci_maxim.c
@@ -137,6 +137,52 @@ static void max_tcpci_init_regs(struct max_tcpci_chip *chip)
 		return;
 }
 
+static int max_tcpci_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_mv)
+{
+	struct max_tcpci_chip *chip = tdata_to_max_tcpci(data);
+	u32 threshold = 0;
+	u8 pwr_ctrl;
+
+	/*
+	 * Indicates that vbus is going to go away due PR_SWAP, hard reset etc.
+	 * Do not discharge vbus here.
+	 */
+	if (requested_vbus_voltage_mv == 0)
+		goto write_thresh;
+
+	if (port_role == TYPEC_SINK) {
+		max_tcpci_read8(chip, TCPC_POWER_CTRL, &pwr_ctrl);
+		if (pwr_ctrl & TCPC_FAST_ROLE_SWAP_EN) {
+			/* To prevent disconnect when the source is fast role swap is capable. */
+			threshold = 3500;
+		} else if (mode == TYPEC_PWR_MODE_PD) {
+			if (pps_active)
+				threshold = (95 * requested_vbus_voltage_mv / 100) - 850;
+			else
+				threshold = (95 * requested_vbus_voltage_mv / 100) - 1250;
+		} else {
+			/* 3.5V for non-pd sink */
+			threshold = 3500;
+		}
+	} else {
+		/* 4V for source */
+		threshold = 4000;
+	}
+
+	threshold = threshold / TCPC_VBUS_SINK_DISCONNECT_THRESH_LSB;
+
+	if (threshold > TCPC_VBUS_SINK_DISCONNECT_THRESH_MAX) {
+		dev_err(chip->dev, "VBUS_SINK_DISCONNECT_THRESH out of range");
+		return -EINVAL;
+	}
+
+write_thresh:
+	return max_tcpci_write16(chip, TCPC_VBUS_SINK_DISCONNECT_THRESH, threshold);
+}
+
 static void process_rx(struct max_tcpci_chip *chip, u16 status)
 {
 	struct pd_message msg;
@@ -454,6 +500,8 @@ static int max_tcpci_probe(struct i2c_client *client, const struct i2c_device_id
 	chip->data.start_drp_toggling = max_tcpci_start_toggling;
 	chip->data.TX_BUF_BYTE_x_hidden = true;
 	chip->data.init = tcpci_init;
+	chip->data.set_auto_vbus_discharge_threshold = max_tcpci_set_auto_vbus_discharge_threshold;
+	chip->data.auto_discharge_disconnect = true;
 
 	max_tcpci_init_regs(chip);
 	chip->tcpci = tcpci_register_port(chip->dev, &chip->data);
-- 
2.28.0.402.g5ffc5be6b7-goog