[PATCH 5/9] platform/x86: lenovo-wmi-capdata: Adopt new WMI API

[Rong Zhang]

The new WMI API supports multiple ACPI types by converting them into a
unified buffer that satisfies alignment and size requirements.

Adopt it to make our life easier.

Note that the new WMI API only accepts a few ACPI types to conform to
the behavior of the Windows WMI-ACPI driver. By adopting the new API, we
intentionally rejects improper ACPI types instead of silently ignoring
them.

Meanwhile, considering that `struct_size(block, data, count * 3)' may
overflow when calculating `count * 3', ignore Fan Test Data with count >
U8_MAX instead of caping `count'.

Signed-off-by: Rong Zhang <i@xxxxxxxx>
---
 drivers/platform/x86/lenovo/wmi-capdata.c | 72 ++++++++++++++-----------------
 1 file changed, 33 insertions(+), 39 deletions(-)

diff --git a/drivers/platform/x86/lenovo/wmi-capdata.c b/drivers/platform/x86/lenovo/wmi-capdata.c
index 793b5103d533..5e66e6b52720 100644
--- a/drivers/platform/x86/lenovo/wmi-capdata.c
+++ b/drivers/platform/x86/lenovo/wmi-capdata.c
@@ -626,17 +626,19 @@ static int __lwmi_cd_cache(struct lwmi_cd_priv *priv)
 	}
 
 	for (idx = 0; idx < priv->list->count; idx++, p += size) {
-		union acpi_object *ret_obj __free(kfree) = NULL;
+		struct wmi_buffer wbuf;
+		int ret;
 
-		ret_obj = wmidev_block_query(priv->wdev, idx);
-		if (!ret_obj)
-			return -ENODEV;
-
-		if (ret_obj->type != ACPI_TYPE_BUFFER ||
-		    ret_obj->buffer.length < size)
+		ret = wmidev_query_block(priv->wdev, idx, &wbuf, size);
+		if (ret == -ENODATA) /* The block is too short, probably stubbed. */
 			continue;
+		if (ret)
+			return ret;
 
-		memcpy(p, ret_obj->buffer.pointer, size);
+		/* Capdata 01 is an extension to capdata 00. */
+		struct capdata00 *capdata __free(kfree) = wbuf.data;
+
+		memcpy(p, capdata, size);
 	}
 
 	return 0;
@@ -677,43 +679,35 @@ static int lwmi_cd_cache(struct lwmi_cd_priv *priv)
  */
 static int lwmi_cd_fan_list_alloc_cache(struct lwmi_cd_priv *priv)
 {
+	struct wmi_buffer wbuf;
 	struct cd_list *list;
-	size_t size;
+	int ret, idx;
 	u32 count;
-	int idx;
 
-	/* Emit unaligned access to u8 buffer with __packed. */
 	struct cd_fan_block {
 		u32 nr;
 		u32 data[]; /* id[nr], max_rpm[nr], min_rpm[nr] */
-	} __packed * block;
-
-	union acpi_object *ret_obj __free(kfree) = wmidev_block_query(priv->wdev, 0);
-	if (!ret_obj)
-		return -ENODEV;
-
-	if (ret_obj->type == ACPI_TYPE_BUFFER) {
-		block = (struct cd_fan_block *)ret_obj->buffer.pointer;
-		size = ret_obj->buffer.length;
-
-		count = size >= sizeof(*block) ? block->nr : 0;
-		if (size < struct_size(block, data, count * 3)) {
-			dev_warn(&priv->wdev->dev,
-				 "incomplete fan test data block: %zu < %zu, ignoring\n",
-				 size, struct_size(block, data, count * 3));
-			count = 0;
-		} else if (count > U8_MAX) {
-			dev_warn(&priv->wdev->dev,
-				 "too many fans reported: %u > %u, truncating\n",
-				 count, U8_MAX);
-			count = U8_MAX;
-		}
-	} else {
-		/*
-		 * This is usually caused by a dummy ACPI method. Do not return an error
-		 * as failing to probe this device will result in sub-master device being
-		 * unbound. This behavior aligns with lwmi_cd_cache().
-		 */
+	};
+
+	ret = wmidev_query_block(priv->wdev, 0, &wbuf, sizeof(struct cd_fan_block));
+	if (ret == -ENODATA) /* The block is too short, probably stubbed. */
+		return 0;
+	if (ret)
+		return ret;
+
+	struct cd_fan_block *block __free(kfree) = wbuf.data;
+
+	count = block->nr;
+
+	if (count > U8_MAX) {
+		dev_warn(&priv->wdev->dev,
+			 "too many fans reported: %u > %u, ignoring\n", count,
+			 U8_MAX);
+		count = 0;
+	} else if (wbuf.length < struct_size(block, data, count * 3)) {
+		dev_warn(&priv->wdev->dev,
+			 "incomplete fan test data block: %zu < %zu (%u fans), ignoring\n",
+			 wbuf.length, struct_size(block, data, count * 3), count);
 		count = 0;
 	}
 

-- 
2.55.0