thermal/drivers/tegra-bpmp: Check if BPMP supports trip points

Check if BPMP supports thermal trip points, and if not,
do not expose the .set_trips callback to the thermal core
framework. This can happen in virtualized environments
where asynchronous communication with VM BPMP drivers is not
available.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20221129153914.2699041-1-cyndis@kapsi.fi

drivers/thermal/tegra/tegra-bpmp-thermal.c

@@ -167,19 +167,69 @@ static int tegra_bpmp_thermal_get_num_zones(struct tegra_bpmp *bpmp,
 	return 0;
 }
 
+static int tegra_bpmp_thermal_trips_supported(struct tegra_bpmp *bpmp, bool *supported)
+{
+	struct mrq_thermal_host_to_bpmp_request req;
+	union mrq_thermal_bpmp_to_host_response reply;
+	struct tegra_bpmp_message msg;
+	int err;
+
+	memset(&req, 0, sizeof(req));
+	req.type = CMD_THERMAL_QUERY_ABI;
+	req.query_abi.type = CMD_THERMAL_SET_TRIP;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_THERMAL;
+	msg.tx.data = &req;
+	msg.tx.size = sizeof(req);
+	msg.rx.data = &reply;
+	msg.rx.size = sizeof(reply);
+
+	err = tegra_bpmp_transfer(bpmp, &msg);
+	if (err)
+		return err;
+
+	if (msg.rx.ret == 0) {
+		*supported = true;
+		return 0;
+	} else if (msg.rx.ret == -BPMP_ENODEV) {
+		*supported = false;
+		return 0;
+	} else {
+		return -EINVAL;
+	}
+}
+
 static const struct thermal_zone_device_ops tegra_bpmp_of_thermal_ops = {
 	.get_temp = tegra_bpmp_thermal_get_temp,
 	.set_trips = tegra_bpmp_thermal_set_trips,
 };
 
+static const struct thermal_zone_device_ops tegra_bpmp_of_thermal_ops_notrips = {
+	.get_temp = tegra_bpmp_thermal_get_temp,
+};
+
 static int tegra_bpmp_thermal_probe(struct platform_device *pdev)
 {
 	struct tegra_bpmp *bpmp = dev_get_drvdata(pdev->dev.parent);
+	const struct thermal_zone_device_ops *thermal_ops;
 	struct tegra_bpmp_thermal *tegra;
 	struct thermal_zone_device *tzd;
 	unsigned int i, max_num_zones;
+	bool supported;
 	int err;
 
+	err = tegra_bpmp_thermal_trips_supported(bpmp, &supported);
+	if (err) {
+		dev_err(&pdev->dev, "failed to determine if trip points are supported\n");
+		return err;
+	}
+
+	if (supported)
+		thermal_ops = &tegra_bpmp_of_thermal_ops;
+	else
+		thermal_ops = &tegra_bpmp_of_thermal_ops_notrips;
+
 	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
 	if (!tegra)
 		return -ENOMEM;
@@ -222,7 +272,7 @@ static int tegra_bpmp_thermal_probe(struct platform_device *pdev)
 		}
 
 		tzd = devm_thermal_of_zone_register(
-			&pdev->dev, i, zone, &tegra_bpmp_of_thermal_ops);
+			&pdev->dev, i, zone, thermal_ops);
 		if (IS_ERR(tzd)) {
 			if (PTR_ERR(tzd) == -EPROBE_DEFER)
 				return -EPROBE_DEFER;