Use the new buffer-based WMI API to also support ACPI firmware
implementations that do not use ACPI buffers for the descriptor.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 .../platform/x86/dell/dell-wmi-descriptor.c   | 96 ++++++++++---------
 1 file changed, 49 insertions(+), 47 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-descriptor.c b/drivers/platform/x86/dell/dell-wmi-descriptor.c
index c2a180202719..621502368895 100644
--- a/drivers/platform/x86/dell/dell-wmi-descriptor.c
+++ b/drivers/platform/x86/dell/dell-wmi-descriptor.c
@@ -7,7 +7,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/acpi.h>
+#include <linux/compiler_attributes.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/wmi.h>
@@ -15,6 +15,24 @@
 
 #define DELL_WMI_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"
 
+/*
+ * Descriptor buffer is 128 byte long and contains:
+ *
+ *       Name             Offset  Length  Value
+ * Vendor Signature          0       4    "DELL"
+ * Object Signature          4       4    " WMI"
+ * WMI Interface Version     8       4    <version>
+ * WMI buffer length        12       4    <length>
+ * WMI hotfix number        16       4    <hotfix>
+ */
+struct descriptor {
+	__le32 vendor_signature;
+	__le32 object_signature;
+	__le32 interface_version;
+	__le32 buffer_length;
+	__le32 hotfix_number;
+} __packed;
+
 struct descriptor_priv {
 	struct list_head list;
 	u32 interface_version;
@@ -88,76 +106,60 @@ bool dell_wmi_get_hotfix(u32 *hotfix)
 }
 EXPORT_SYMBOL_GPL(dell_wmi_get_hotfix);
 
-/*
- * Descriptor buffer is 128 byte long and contains:
- *
- *       Name             Offset  Length  Value
- * Vendor Signature          0       4    "DELL"
- * Object Signature          4       4    " WMI"
- * WMI Interface Version     8       4    <version>
- * WMI buffer length        12       4    <length>
- * WMI hotfix number        16       4    <hotfix>
- */
-static int dell_wmi_descriptor_probe(struct wmi_device *wdev,
-				     const void *context)
+static int dell_wmi_descriptor_probe(struct wmi_device *wdev, const void *context)
 {
-	union acpi_object *obj = NULL;
 	struct descriptor_priv *priv;
-	u32 *buffer;
+	struct wmi_buffer buffer;
+	struct descriptor *desc;
 	int ret;
 
-	obj = wmidev_block_query(wdev, 0);
-	if (!obj) {
-		dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");
-		ret = -EIO;
-		goto out;
-	}
+	ret = wmidev_query_block(wdev, 0, &buffer);
+	if (ret < 0)
+		return ret;
 
-	if (obj->type != ACPI_TYPE_BUFFER) {
-		dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
+	if (buffer.length < sizeof(*desc)) {
+		dev_err(&wdev->dev,
+			"Dell descriptor buffer contains not enough data (%zu)\n",
+			buffer.length);
 		ret = -EINVAL;
 		descriptor_valid = ret;
 		goto out;
 	}
 
-	/* Although it's not technically a failure, this would lead to
-	 * unexpected behavior
-	 */
-	if (obj->buffer.length != 128) {
-		dev_err(&wdev->dev,
-			"Dell descriptor buffer has unexpected length (%d)\n",
-			obj->buffer.length);
-		ret = -EINVAL;
+	desc = buffer.data;
+
+	/* "DELL" */
+	if (le32_to_cpu(desc->vendor_signature) != 0x4C4C4544) {
+		dev_err(&wdev->dev, "Dell descriptor buffer has invalid vendor signature (%u)\n",
+			le32_to_cpu(desc->vendor_signature));
+		ret = -ENOMSG;
 		descriptor_valid = ret;
 		goto out;
 	}
 
-	buffer = (u32 *)obj->buffer.pointer;
-
-	if (strncmp(obj->string.pointer, "DELL WMI", 8) != 0) {
-		dev_err(&wdev->dev, "Dell descriptor buffer has invalid signature (%8ph)\n",
-			buffer);
-		ret = -EINVAL;
+	/* " WMI" */
+	if (le32_to_cpu(desc->object_signature) != 0x494D5720) {
+		dev_err(&wdev->dev, "Dell descriptor buffer has invalid object signature (%u)\n",
+			le32_to_cpu(desc->object_signature));
+		ret = -ENOMSG;
 		descriptor_valid = ret;
 		goto out;
 	}
 	descriptor_valid = 0;
 
-	if (buffer[2] != 0 && buffer[2] != 1)
-		dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%lu)\n",
-			(unsigned long) buffer[2]);
-
-	priv = devm_kzalloc(&wdev->dev, sizeof(struct descriptor_priv),
-	GFP_KERNEL);
+	if (le32_to_cpu(desc->interface_version) > 2)
+		dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%u)\n",
+			 le32_to_cpu(desc->interface_version));
 
+	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
-	priv->interface_version = buffer[2];
-	priv->size = buffer[3];
-	priv->hotfix = buffer[4];
+	priv->interface_version = le32_to_cpu(desc->interface_version);
+	priv->size = le32_to_cpu(desc->buffer_length);
+	priv->hotfix = le32_to_cpu(desc->hotfix_number);
 	ret = 0;
 	dev_set_drvdata(&wdev->dev, priv);
 	mutex_lock(&list_mutex);
@@ -170,7 +172,7 @@ static int dell_wmi_descriptor_probe(struct wmi_device *wdev,
 		(unsigned long) priv->hotfix);
 
 out:
-	kfree(obj);
+	kfree(buffer.data);
 	return ret;
 }
 
-- 
2.39.5