ASoC: rt5514: Voice wakeup support.

If the rt5514 Wake on Voice device is opened while suspended, it will
be able to wake up the system when a voice command is detected.
This patch also supports user-space policy to override wakeup behavior
by /sys/bus/spi/drivers/rt5514/spi2.0/power/wakeup.
Signed-off-by: Chinyue Chen <chinyue@chromium.org>
Signed-off-by: Oder Chiou <oder_chiou@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt5514-spi.c

@@ -456,9 +456,35 @@ static int rt5514_spi_probe(struct spi_device *spi)
 		return ret;
 	}
 
+	device_init_wakeup(&spi->dev, true);
+
+	return 0;
+}
+
+static int rt5514_suspend(struct device *dev)
+{
+	int irq = to_spi_device(dev)->irq;
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(irq);
+
 	return 0;
 }
 
+static int rt5514_resume(struct device *dev)
+{
+	int irq = to_spi_device(dev)->irq;
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(irq);
+
+	return 0;
+}
+
+static const struct dev_pm_ops rt5514_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(rt5514_suspend, rt5514_resume)
+};
+
 static const struct of_device_id rt5514_of_match[] = {
 	{ .compatible = "realtek,rt5514", },
 	{},
@@ -468,6 +494,7 @@ MODULE_DEVICE_TABLE(of, rt5514_of_match);
 static struct spi_driver rt5514_spi_driver = {
 	.driver = {
 		.name = "rt5514",
+		.pm = &rt5514_pm_ops,
 		.of_match_table = of_match_ptr(rt5514_of_match),
 	},
 	.probe = rt5514_spi_probe,