thermal: tango: add resume support

When this platform is suspended, firmware powers the entire SoC down,
except a few hardware blocks waiting for wakeup events. There is no
context to save for this particular block.

Therefore, there is nothing useful for the driver to do on suspend;
so we define a NULL suspend hook. On resume, the driver initializes
the block exactly as is done in the probe callback.
Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/tango_thermal.c

@@ -64,6 +64,12 @@ static const struct thermal_zone_of_device_ops ops = {
 	.get_temp	= tango_get_temp,
 };
 
+static void tango_thermal_init(struct tango_thermal_priv *priv)
+{
+	writel(0, priv->base + TEMPSI_CFG);
+	writel(CMD_ON, priv->base + TEMPSI_CMD);
+}
+
 static int tango_thermal_probe(struct platform_device *pdev)
 {
 	struct resource *res;
@@ -79,14 +85,22 @@ static int tango_thermal_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
 
+	platform_set_drvdata(pdev, priv);
 	priv->thresh_idx = IDX_MIN;
-	writel(0, priv->base + TEMPSI_CFG);
-	writel(CMD_ON, priv->base + TEMPSI_CMD);
+	tango_thermal_init(priv);
 
 	tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, priv, &ops);
 	return PTR_ERR_OR_ZERO(tzdev);
 }
 
+static int __maybe_unused tango_thermal_resume(struct device *dev)
+{
+	tango_thermal_init(dev_get_drvdata(dev));
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(tango_thermal_pm, NULL, tango_thermal_resume);
+
 static const struct of_device_id tango_sensor_ids[] = {
 	{
 		.compatible = "sigma,smp8758-thermal",
@@ -99,6 +113,7 @@ static struct platform_driver tango_thermal_driver = {
 	.driver	= {
 		.name		= "tango-thermal",
 		.of_match_table	= tango_sensor_ids,
+		.pm		= &tango_thermal_pm,
 	},
 };