iio: trigger: allow devices to suspend/resume theirs associated trigger

When a machine enters a sleep state while a trigger is associated to
an iio device that trigger is not resumed after exiting the sleep state:
provide iio device drivers a way to suspend and resume
the associated trigger to solve the aforementioned bug.

Each iio driver supporting external triggers is expected to call
iio_device_suspend_triggering before suspending,
and iio_device_resume_triggering upon resuming.

Signed-off-by: Denis Benato <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/industrialio-trigger.c

···
 	iio_trigger_put_irq(trig, pf->irq);
 	free_irq(pf->irq, pf);
 	module_put(iio_dev_opaque->driver_module);
+	pf->irq = 0;
 
 	return ret;
 }
···
 	if (indio_dev->trig)
 		iio_trigger_put(indio_dev->trig);
 }
+
+int iio_device_suspend_triggering(struct iio_dev *indio_dev)
+{
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+	guard(mutex)(&iio_dev_opaque->mlock);
+
+	if ((indio_dev->pollfunc) && (indio_dev->pollfunc->irq > 0))
+		disable_irq(indio_dev->pollfunc->irq);
+
+	return 0;
+}
+EXPORT_SYMBOL(iio_device_suspend_triggering);
+
+int iio_device_resume_triggering(struct iio_dev *indio_dev)
+{
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+	guard(mutex)(&iio_dev_opaque->mlock);
+
+	if ((indio_dev->pollfunc) && (indio_dev->pollfunc->irq > 0))
+		enable_irq(indio_dev->pollfunc->irq);
+
+	return 0;
+}
+EXPORT_SYMBOL(iio_device_resume_triggering);

include/linux/iio/iio.h

···
 }
 #endif
 
+/**
+ * iio_device_suspend_triggering() - suspend trigger attached to an iio_dev
+ * @indio_dev: iio_dev associated with the device that will have triggers suspended
+ *
+ * Return 0 if successful, negative otherwise
+ **/
+int iio_device_suspend_triggering(struct iio_dev *indio_dev);
+
+/**
+ * iio_device_resume_triggering() - resume trigger attached to an iio_dev
+ *	that was previously suspended with iio_device_suspend_triggering()
+ * @indio_dev: iio_dev associated with the device that will have triggers resumed
+ *
+ * Return 0 if successful, negative otherwise
+ **/
+int iio_device_resume_triggering(struct iio_dev *indio_dev);
+
 #ifdef CONFIG_ACPI
 bool iio_read_acpi_mount_matrix(struct device *dev,
 				struct iio_mount_matrix *orientation,