serial: qcom-geni: Enable PM runtime for serial driver

The GENI serial driver currently handles power resource management through calls to the statically defined geni_serial_resources_on() and geni_serial_resources_off() functions. This approach reduces modularity and limits support for platforms with diverse power management mechanisms, including resource managed by firmware. Improve modularity and enable better integration with platform-specific power management, introduce support for runtime PM. Use pm_runtime_resume_and_get() and pm_runtime_put_sync() within the qcom_geni_serial_pm() callback to control resource power state transitions based on UART power state changes. Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com> Link: https://lore.kernel.org/r/20250721174532.14022-8-quic_ptalari@quicinc.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Praveen Talari

drivers/tty/serial/qcom_geni_serial.c

@@ -1713,10 +1713,10 @@ static void qcom_geni_serial_pm(struct uart_port *uport,
 old_state = UART_PM_STATE_OFF;
 
 if (new_state == UART_PM_STATE_ON && old_state == UART_PM_STATE_OFF)
-geni_serial_resources_on(uport);
+pm_runtime_resume_and_get(uport->dev);
 else if (new_state == UART_PM_STATE_OFF &&
  old_state == UART_PM_STATE_ON)
-geni_serial_resources_off(uport);
+pm_runtime_put_sync(uport->dev);
 
 }
 
@@ -1878,6 +1878,8 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 if (ret)
 return ret;
 
+devm_pm_runtime_enable(port->se.dev);
+
 ret = uart_add_one_port(drv, uport);
 if (ret)
 return ret;
@@ -1909,6 +1911,22 @@ static void qcom_geni_serial_remove(struct platform_device *pdev)
 uart_remove_one_port(drv, &port->uport);
 }
 
+static int __maybe_unused qcom_geni_serial_runtime_suspend(struct device *dev)
+{
+struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
+struct uart_port *uport = &port->uport;
+
+return geni_serial_resources_off(uport);
+}
+
+static int __maybe_unused qcom_geni_serial_runtime_resume(struct device *dev)
+{
+struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
+struct uart_port *uport = &port->uport;
+
+return geni_serial_resources_on(uport);
+}
+
 static int qcom_geni_serial_suspend(struct device *dev)
 {
 struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
@@ -1952,6 +1970,8 @@ static const struct qcom_geni_device_data qcom_geni_uart_data = {
 };
 
 static const struct dev_pm_ops qcom_geni_serial_pm_ops = {
+SET_RUNTIME_PM_OPS(qcom_geni_serial_runtime_suspend,
+ qcom_geni_serial_runtime_resume, NULL)
 SYSTEM_SLEEP_PM_OPS(qcom_geni_serial_suspend, qcom_geni_serial_resume)
 };