usbc: add event-driven handling of CC lines changes in ps8815 driver

Add bool value that stores the CC change information received in
the interrupt of TCPC alert line. In sink role when in disconnected
state, polling the CC lines causes the chip to be awaken from sleep
mode increasing the power usage. When partner is connected, or any
other CC lines change happens, the chip informs about it with alert.
It can be cached and used instead of asking the chip directly.

Signed-off-by: Michał Barnaś <[email protected]>

Author: barnas-michal

drivers/usb_c/tcpc/ps8xxx.c

@@ -46,6 +46,8 @@ struct ps8xxx_data {
 	/** Polarity of CC lines for PD and VCONN */
 	enum tc_cc_polarity cc_polarity;
 
+	/** Boolean value if there was a change on the CC lines since last check */
+	bool cc_changed;
 	/** State of CC1 line */
 	enum tc_cc_voltage_state cc1;
 	/** State of CC2 line */
@@ -107,6 +109,15 @@ int ps8xxx_tcpc_get_cc(const struct device *dev, enum tc_cc_voltage_state *cc1,
 		return -EIO;
 	}
 
+	if (IS_ENABLED(CONFIG_USBC_CSM_SINK_ONLY) && !data->cc_changed) {
+		*cc1 = data->cc1;
+		*cc2 = data->cc2;
+
+		return 0;
+	}
+
+	data->cc_changed = false;
+
 	ret = tcpci_tcpm_get_cc(&cfg->bus, cc1, cc2);
 
 	if (IS_ENABLED(CONFIG_USBC_CSM_SINK_ONLY) || *cc1 != data->cc1 || *cc2 != data->cc2) {
@@ -123,6 +134,8 @@ int ps8xxx_tcpc_select_rp_value(const struct device *dev, enum tc_rp_value rp)
 	const struct ps8xxx_cfg *cfg = dev->config;
 	struct ps8xxx_data *data = dev->data;
 
+	data->cc_changed = true;
+
 	return tcpci_update_reg8(&cfg->bus, TCPC_REG_ROLE_CTRL, TCPC_REG_ROLE_CTRL_RP_MASK,
 				 TCPC_REG_ROLE_CTRL_SET(0, rp, 0, 0));
 }
@@ -148,6 +161,8 @@ int ps8xxx_tcpc_set_cc(const struct device *dev, enum tc_cc_pull pull)
 		return -EIO;
 	}
 
+	data->cc_changed = true;
+
 	return tcpci_update_reg8(&cfg->bus, TCPC_REG_ROLE_CTRL,
 				 TCPC_REG_ROLE_CTRL_CC1_MASK | TCPC_REG_ROLE_CTRL_CC2_MASK,
 				 TCPC_REG_ROLE_CTRL_SET(0, 0, pull, pull));
@@ -188,6 +203,7 @@ int ps8xxx_tcpc_set_vconn(const struct device *dev, bool enable)
 		return -EIO;
 	}
 
+	data->cc_changed = true;
 	ret = tcpci_update_reg8(&cfg->bus, TCPC_REG_POWER_CTRL, TCPC_REG_POWER_CTRL_VCONN_EN,
 				enable ? TCPC_REG_POWER_CTRL_VCONN_EN : 0);
 
@@ -309,6 +325,7 @@ int ps8xxx_tcpc_set_cc_polarity(const struct device *dev, enum tc_cc_polarity po
 		return ret;
 	}
 
+	data->cc_changed = true;
 	data->cc_polarity = polarity;
 	return 0;
 }
@@ -589,6 +606,7 @@ void ps8xxx_alert_work_cb(struct k_work *work)
 		if (alert_type == TCPC_ALERT_HARD_RESET_RECEIVED) {
 			LOG_DBG("PS8xxx hard rst received");
 			tcpci_init_alert_mask(dev);
+			data->cc_changed = true;
 		} else if (alert_type == TCPC_ALERT_FAULT_STATUS) {
 			uint8_t fault;
 
@@ -602,6 +620,7 @@ void ps8xxx_alert_work_cb(struct k_work *work)
 			tcpci_read_reg8(&cfg->bus, TCPC_REG_EXT_STATUS, &ext_status);
 			tcpci_write_reg8(&cfg->bus, TCPC_REG_EXT_STATUS, ext_status);
 
+			data->cc_changed = true;
 			LOG_DBG("PS8xxx ext status: %02x", ext_status);
 		} else if (alert_type == TCPC_ALERT_POWER_STATUS) {
 			uint8_t pwr_status;
@@ -619,6 +638,8 @@ void ps8xxx_alert_work_cb(struct k_work *work)
 			LOG_DBG("PS8xxx ext alert: %02x", alert_status);
 		} else if (alert_type == TCPC_ALERT_MSG_STATUS) {
 			data->msg_pending = true;
+		} else if (alert_type == TCPC_ALERT_CC_STATUS) {
+			data->cc_changed = true;
 		}
 
 		if (data->alert_handler != NULL) {
@@ -711,6 +732,7 @@ static int ps8xxx_dev_init(const struct device *dev)
 	{                                                                                          \
 		.dev = DEVICE_DT_GET(node),                                                        \
 		.init_retries = 0,                                                                 \
+		.cc_changed = true,                                                                \
 	}
 
 #define PS8XXX_DRIVER_CFG_INIT(node)                                                               \