thermal/int340x_thermal: Don't require IDSP to exist

The IDSP method doesn't appear to exist on the most recent Intel platforms:
instead, the IDSP data is included in the GDDV blob. Since we probably
don't want to decompress and parse that in-kernel, just allow any UUID to
be written if IDSP is missing.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Tested-by: Pandruvada, Srinivas <srinivas.pandruvada@linux.intel.com>
[ rzhang: fix checkpatch warning in changelog ]
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20200414020953.255364-3-matthewgarrett@google.com
diff --git a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
index 87d9b07..0b3a626 100644
--- a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
+++ b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
@@ -96,6 +96,9 @@
 	int i;
 	int length = 0;
 
+	if (!priv->uuid_bitmap)
+		return sprintf(buf, "UNKNOWN\n");
+
 	for (i = 0; i < INT3400_THERMAL_MAXIMUM_UUID; i++) {
 		if (priv->uuid_bitmap & (1 << i))
 			if (PAGE_SIZE - length > 0)
@@ -113,11 +116,11 @@
 {
 	struct int3400_thermal_priv *priv = dev_get_drvdata(dev);
 
-	if (priv->uuid_bitmap & (1 << priv->current_uuid_index))
-		return sprintf(buf, "%s\n",
-			       int3400_thermal_uuids[priv->current_uuid_index]);
-	else
+	if (priv->current_uuid_index == -1)
 		return sprintf(buf, "INVALID\n");
+
+	return sprintf(buf, "%s\n",
+		       int3400_thermal_uuids[priv->current_uuid_index]);
 }
 
 static ssize_t current_uuid_store(struct device *dev,
@@ -128,9 +131,16 @@
 	int i;
 
 	for (i = 0; i < INT3400_THERMAL_MAXIMUM_UUID; ++i) {
-		if ((priv->uuid_bitmap & (1 << i)) &&
-		    !(strncmp(buf, int3400_thermal_uuids[i],
-			      sizeof(int3400_thermal_uuids[i]) - 1))) {
+		if (!strncmp(buf, int3400_thermal_uuids[i],
+			     sizeof(int3400_thermal_uuids[i]) - 1)) {
+			/*
+			 * If we have a list of supported UUIDs, make sure
+			 * this one is supported.
+			 */
+			if (priv->uuid_bitmap &&
+			    !(priv->uuid_bitmap & (1 << i)))
+				return -EINVAL;
+
 			priv->current_uuid_index = i;
 			return count;
 		}
@@ -464,9 +474,13 @@
 	priv->adev = adev;
 
 	result = int3400_thermal_get_uuids(priv);
-	if (result)
+
+	/* Missing IDSP isn't fatal */
+	if (result && result != -ENODEV)
 		goto free_priv;
 
+	priv->current_uuid_index = -1;
+
 	result = acpi_parse_art(priv->adev->handle, &priv->art_count,
 				&priv->arts, true);
 	if (result)