tty: serial: qcom-geni-serial: Add support for Hibernation feature

Added changes to support the hibernation feature for serial UART.
Added support for freeze, restore and thaw callbacks to put the
device into hibernation.
Signed-off-by: Aniket Randive <quic_arandive@quicinc.com>
Link: https://lore.kernel.org/r/1665123780-20557-1-git-send-email-quic_arandive@quicinc.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -924,6 +924,7 @@ static int qcom_geni_serial_port_setup(struct uart_port *uport)
 			       false, true, true);
 	geni_se_init(&port->se, UART_RX_WM, port->rx_fifo_depth - 2);
 	geni_se_select_mode(&port->se, GENI_SE_FIFO);
+	qcom_geni_serial_start_rx(uport);
 	port->setup = true;
 
 	return 0;
@@ -1547,9 +1548,43 @@ static int __maybe_unused qcom_geni_serial_sys_resume(struct device *dev)
 	return ret;
 }
 
+static int qcom_geni_serial_sys_hib_resume(struct device *dev)
+{
+	int ret = 0;
+	struct uart_port *uport;
+	struct qcom_geni_private_data *private_data;
+	struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
+
+	uport = &port->uport;
+	private_data = uport->private_data;
+
+	if (uart_console(uport)) {
+		geni_icc_set_tag(&port->se, 0x7);
+		geni_icc_set_bw(&port->se);
+		ret = uart_resume_port(private_data->drv, uport);
+		/*
+		 * For hibernation usecase clients for
+		 * console UART won't call port setup during restore,
+		 * hence call port setup for console uart.
+		 */
+		qcom_geni_serial_port_setup(uport);
+	} else {
+		/*
+		 * Peripheral register settings are lost during hibernation.
+		 * Update setup flag such that port setup happens again
+		 * during next session. Clients of HS-UART will close and
+		 * open the port during hibernation.
+		 */
+		port->setup = false;
+	}
+	return ret;
+}
+
 static const struct dev_pm_ops qcom_geni_serial_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(qcom_geni_serial_sys_suspend,
 					qcom_geni_serial_sys_resume)
+	.restore = qcom_geni_serial_sys_hib_resume,
+	.thaw = qcom_geni_serial_sys_hib_resume,
 };
 
 static const struct of_device_id qcom_geni_serial_match_table[] = {