Add Power Management (PM) runtime support to Qualcomm GENI
serial driver.

Introduce necessary callbacks and updates to ensure seamless
transitions between power states, enhancing overall power
efficiency.

Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
---
 drivers/tty/serial/qcom_geni_serial.c | 33 +++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 60afee3884a6..9d698c354510 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1686,10 +1686,10 @@ 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);
 
 }
 
@@ -1827,9 +1827,11 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	pm_runtime_enable(port->se.dev);
+
 	ret = uart_add_one_port(drv, uport);
 	if (ret)
-		return ret;
+		goto error;
 
 	if (port->wakeup_irq > 0) {
 		device_init_wakeup(&pdev->dev, true);
@@ -1839,11 +1841,15 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 			device_init_wakeup(&pdev->dev, false);
 			ida_free(&port_ida, uport->line);
 			uart_remove_one_port(drv, uport);
-			return ret;
+			goto error;
 		}
 	}
 
 	return 0;
+
+error:
+	pm_runtime_disable(port->se.dev);
+	return ret;
 }
 
 static void qcom_geni_serial_remove(struct platform_device *pdev)
@@ -1855,9 +1861,26 @@ static void qcom_geni_serial_remove(struct platform_device *pdev)
 	dev_pm_clear_wake_irq(&pdev->dev);
 	device_init_wakeup(&pdev->dev, false);
 	ida_free(&port_ida, uport->line);
+	pm_runtime_disable(port->se.dev);
 	uart_remove_one_port(drv, &port->uport);
 }
 
+static int 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 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);
@@ -1901,6 +1924,8 @@ 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)
 };
 
-- 
2.17.1

Hi Praveen,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 3e039dcc9c1320c0d33ddd51c372dcc91d3ea3c7]

url:    https://github.com/intel-lab-lkp/linux/commits/Praveen-Talari/opp-add-new-helper-API-dev_pm_opp_set_level/20250502-111540
base:   3e039dcc9c1320c0d33ddd51c372dcc91d3ea3c7
patch link:    https://lore.kernel.org/r/20250502031018.1292-9-quic_ptalari%40quicinc.com
patch subject: [PATCH v3 8/9] serial: qcom-geni: Enable PM runtime for serial driver
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20250507/202505071523.FhPMXslL-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250507/202505071523.FhPMXslL-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505071523.FhPMXslL-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/tty/serial/qcom_geni_serial.c:1876:12: warning: 'qcom_geni_serial_runtime_resume' defined but not used [-Wunused-function]
    1876 | static int qcom_geni_serial_runtime_resume(struct device *dev)
         |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/tty/serial/qcom_geni_serial.c:1868:12: warning: 'qcom_geni_serial_runtime_suspend' defined but not used [-Wunused-function]
    1868 | static int qcom_geni_serial_runtime_suspend(struct device *dev)
         |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/qcom_geni_serial_runtime_resume +1876 drivers/tty/serial/qcom_geni_serial.c

  1867	
> 1868	static int qcom_geni_serial_runtime_suspend(struct device *dev)
  1869	{
  1870		struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
  1871		struct uart_port *uport = &port->uport;
  1872	
  1873		return geni_serial_resources_off(uport);
  1874	};
  1875	
> 1876	static int qcom_geni_serial_runtime_resume(struct device *dev)
  1877	{
  1878		struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
  1879		struct uart_port *uport = &port->uport;
  1880	
  1881		return geni_serial_resources_on(uport);
  1882	};
  1883	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki