can: tcan4x5x: support resuming from rx interrupt signal

Implement the "wakeup-source" device tree property, so the chip is left
running when suspending, and its rx interrupt is used as a wakeup source
to resume operation.
Signed-off-by: Martin Hundebøll <martin@geanix.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/tcan4x5x-core.c

@@ -411,7 +411,7 @@ static int tcan4x5x_can_probe(struct spi_device *spi)
 	priv->spi = spi;
 
 	mcan_class->pm_clock_support = 0;
-	mcan_class->pm_wake_source = 0;
+	mcan_class->pm_wake_source = device_property_read_bool(&spi->dev, "wakeup-source");
 	mcan_class->can.clock.freq = freq;
 	mcan_class->dev = &spi->dev;
 	mcan_class->ops = &tcan4x5x_ops;
@@ -460,6 +460,9 @@ static int tcan4x5x_can_probe(struct spi_device *spi)
 		goto out_power;
 	}
 
+	if (mcan_class->pm_wake_source)
+		device_init_wakeup(&spi->dev, true);
+
 	ret = m_can_class_register(mcan_class);
 	if (ret) {
 		dev_err(&spi->dev, "Failed registering m_can device %pe\n",
@@ -488,6 +491,29 @@ static void tcan4x5x_can_remove(struct spi_device *spi)
 	m_can_class_free_dev(priv->cdev.net);
 }
 
+static int __maybe_unused tcan4x5x_suspend(struct device *dev)
+{
+	struct m_can_classdev *cdev = dev_get_drvdata(dev);
+	struct spi_device *spi = to_spi_device(dev);
+
+	if (cdev->pm_wake_source)
+		enable_irq_wake(spi->irq);
+
+	return m_can_class_suspend(dev);
+}
+
+static int __maybe_unused tcan4x5x_resume(struct device *dev)
+{
+	struct m_can_classdev *cdev = dev_get_drvdata(dev);
+	struct spi_device *spi = to_spi_device(dev);
+	int ret = m_can_class_resume(dev);
+
+	if (cdev->pm_wake_source)
+		disable_irq_wake(spi->irq);
+
+	return ret;
+}
+
 static const struct of_device_id tcan4x5x_of_match[] = {
 	{
 		.compatible = "ti,tcan4x5x",
@@ -506,11 +532,15 @@ static const struct spi_device_id tcan4x5x_id_table[] = {
 };
 MODULE_DEVICE_TABLE(spi, tcan4x5x_id_table);
 
+static const struct dev_pm_ops tcan4x5x_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(tcan4x5x_suspend, tcan4x5x_resume)
+};
+
 static struct spi_driver tcan4x5x_can_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
 		.of_match_table = tcan4x5x_of_match,
-		.pm = NULL,
+		.pm = &tcan4x5x_pm_ops,
 	},
 	.id_table = tcan4x5x_id_table,
 	.probe = tcan4x5x_can_probe,