iwlwifi: mvm: fix the return type for DSM functions 1 and 2

The return type value of functions 1 and 2 were considered to be an
integer inside a buffer, but they can also be only an integer, without
the buffer.  Fix the code in iwl_acpi_get_dsm_u8() to handle it as a
single integer value, as well as packed inside a buffer.

Signed-off-by: Matt Chen <matt.chen@intel.com>
Fixes: 9db93491f29e ("iwlwifi: acpi: support device specific method (DSM)")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20210122144849.5757092adcd6.Ic24524627b899c9a01af38107a62a626bdf5ae3a@changeid

1 files changed, 50 insertions, 15 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/fw/acpi.c b/drivers/net/wireless/intel/iwlwifi/fw/acpi.c
index 15248b064380..d8b7776a8dde 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/acpi.c
+++ b/drivers/net/wireless/intel/iwlwifi/fw/acpi.c
@@ -80,19 +80,45 @@ static void *iwl_acpi_get_dsm_object(struct device *dev, int rev, int func,
 }
 
 /*
- * Evaluate a DSM with no arguments and a single u8 return value (inside a
- * buffer object), verify and return that value.
+ * Generic function to evaluate a DSM with no arguments
+ * and an integer return value,
+ * (as an integer object or inside a buffer object),
+ * verify and assign the value in the "value" parameter.
+ * return 0 in success and the appropriate errno otherwise.
  */
-int iwl_acpi_get_dsm_u8(struct device *dev, int rev, int func)
+static int iwl_acpi_get_dsm_integer(struct device *dev, int rev, int func,
+				    u64 *value, size_t expected_size)
 {
 	union acpi_object *obj;
-	int ret;
+	int ret = 0;
 
 	obj = iwl_acpi_get_dsm_object(dev, rev, func, NULL);
-	if (IS_ERR(obj))
+	if (IS_ERR(obj)) {
+		IWL_DEBUG_DEV_RADIO(dev,
+				    "Failed to get  DSM object. func= %d\n",
+				    func);
 		return -ENOENT;
+	}
+
+	if (obj->type == ACPI_TYPE_INTEGER) {
+		*value = obj->integer.value;
+	} else if (obj->type == ACPI_TYPE_BUFFER) {
+		__le64 le_value = 0;
 
-	if (obj->type != ACPI_TYPE_BUFFER) {
+		if (WARN_ON_ONCE(expected_size > sizeof(le_value)))
+			return -EINVAL;
+
+		/* if the buffer size doesn't match the expected size */
+		if (obj->buffer.length != expected_size)
+			IWL_DEBUG_DEV_RADIO(dev,
+					    "ACPI: DSM invalid buffer size, padding or truncating (%d)\n",
+					    obj->buffer.length);
+
+		 /* assuming LE from Intel BIOS spec */
+		memcpy(&le_value, obj->buffer.pointer,
+		       min_t(size_t, expected_size, (size_t)obj->buffer.length));
+		*value = le64_to_cpu(le_value);
+	} else {
 		IWL_DEBUG_DEV_RADIO(dev,
 				    "ACPI: DSM method did not return a valid object, type=%d\n",
 				    obj->type);
@@ -100,15 +126,6 @@ int iwl_acpi_get_dsm_u8(struct device *dev, int rev, int func)
 		goto out;
 	}
 
-	if (obj->buffer.length != sizeof(u8)) {
-		IWL_DEBUG_DEV_RADIO(dev,
-				    "ACPI: DSM method returned invalid buffer, length=%d\n",
-				    obj->buffer.length);
-		ret = -EINVAL;
-		goto out;
-	}
-
-	ret = obj->buffer.pointer[0];
 	IWL_DEBUG_DEV_RADIO(dev,
 			    "ACPI: DSM method evaluated: func=%d, ret=%d\n",
 			    func, ret);
@@ -116,6 +133,24 @@ out:
 	ACPI_FREE(obj);
 	return ret;
 }
+
+/*
+ * Evaluate a DSM with no arguments and a u8 return value,
+ */
+int iwl_acpi_get_dsm_u8(struct device *dev, int rev, int func, u8 *value)
+{
+	int ret;
+	u64 val;
+
+	ret = iwl_acpi_get_dsm_integer(dev, rev, func, &val, sizeof(u8));
+
+	if (ret < 0)
+		return ret;
+
+	/* cast val (u64) to be u8 */
+	*value = (u8)val;
+	return 0;
+}
 IWL_EXPORT_SYMBOL(iwl_acpi_get_dsm_u8);
 
 union acpi_object *iwl_acpi_get_wifi_pkg(struct device *dev,