[PATCH 3/6] iio: adc: versal-sysmon: disable interrupts on shutdown

[Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>]

Interrupt teardown is registered with devm_add_action_or_reset(), so
sysmon_disable_interrupts() runs when the driver is unbound but not when
the system shuts down: device_shutdown() invokes only the driver's
.shutdown callback, which this driver does not implement.

The device is therefore left with its alarm interrupts enabled in
hardware once Linux has stopped servicing them.

Add a .shutdown callback performing the same teardown, so the device is
quiesced before control is handed on. The helper lives in the core
module, so it is exported for the platform front-end. It skips a
device described without an interrupt, which never set up interrupt
handling.

Disabling the interrupts at shutdown is safe to have and not a must have
requirement for shutdown.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
---
 drivers/iio/adc/versal-sysmon-core.c | 19 +++++++++++++++++++
 drivers/iio/adc/versal-sysmon.c      |  6 ++++++
 drivers/iio/adc/versal-sysmon.h      |  1 +
 3 files changed, 26 insertions(+)

diff --git a/drivers/iio/adc/versal-sysmon-core.c b/drivers/iio/adc/versal-sysmon-core.c
index 6595d07038c1..d39aaba9a8b6 100644
--- a/drivers/iio/adc/versal-sysmon-core.c
+++ b/drivers/iio/adc/versal-sysmon-core.c
@@ -1000,6 +1000,8 @@ int devm_versal_sysmon_core_probe(struct device *dev, struct regmap *regmap)
 	if (!indio_dev)
 		return -ENOMEM;
 
+	dev_set_drvdata(dev, indio_dev);
+
 	sysmon = iio_priv(indio_dev);
 	sysmon->regmap = regmap;
 	sysmon->temp_oversampling = 1;
@@ -1050,6 +1052,23 @@ int devm_versal_sysmon_core_probe(struct device *dev, struct regmap *regmap)
 }
 EXPORT_SYMBOL_NS_GPL(devm_versal_sysmon_core_probe, "VERSAL_SYSMON");
 
+/**
+ * versal_sysmon_shutdown() - Disable SysMon interrupts on system shutdown
+ * @dev: SysMon device
+ *
+ * Interrupt teardown is a devm action, which runs on driver unbind but not
+ * on system shutdown, so disable the interrupts here as well.
+ */
+void versal_sysmon_shutdown(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct sysmon *sysmon = iio_priv(indio_dev);
+
+	if (sysmon->irq > 0)
+		sysmon_disable_interrupts(sysmon);
+}
+EXPORT_SYMBOL_NS_GPL(versal_sysmon_shutdown, "VERSAL_SYSMON");
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("AMD Versal SysMon Core Driver");
 MODULE_AUTHOR("Salih Erim <salih.erim@amd.com>");
diff --git a/drivers/iio/adc/versal-sysmon.c b/drivers/iio/adc/versal-sysmon.c
index 529d0486c9f9..4d5e3d14cf15 100644
--- a/drivers/iio/adc/versal-sysmon.c
+++ b/drivers/iio/adc/versal-sysmon.c
@@ -71,6 +71,11 @@ static int sysmon_platform_probe(struct platform_device *pdev)
 	return devm_versal_sysmon_core_probe(dev, regmap);
 }
 
+static void sysmon_platform_shutdown(struct platform_device *pdev)
+{
+	versal_sysmon_shutdown(&pdev->dev);
+}
+
 static const struct of_device_id sysmon_of_match_table[] = {
 	{ .compatible = "xlnx,versal-sysmon" },
 	{ }
@@ -79,6 +84,7 @@ MODULE_DEVICE_TABLE(of, sysmon_of_match_table);
 
 static struct platform_driver sysmon_platform_driver = {
 	.probe = sysmon_platform_probe,
+	.shutdown = sysmon_platform_shutdown,
 	.driver = {
 		.name = "versal-sysmon",
 		.of_match_table = sysmon_of_match_table,
diff --git a/drivers/iio/adc/versal-sysmon.h b/drivers/iio/adc/versal-sysmon.h
index a1ac3289719c..a21dacc13471 100644
--- a/drivers/iio/adc/versal-sysmon.h
+++ b/drivers/iio/adc/versal-sysmon.h
@@ -122,5 +122,6 @@ struct sysmon {
 };
 
 int devm_versal_sysmon_core_probe(struct device *dev, struct regmap *regmap);
+void versal_sysmon_shutdown(struct device *dev);
 
 #endif /* _VERSAL_SYSMON_H_ */
-- 
2.34.1